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CN111790353A - Adsorbent for removing heavy metals in humic acid fertilizer, preparation method and application method - Google Patents

Adsorbent for removing heavy metals in humic acid fertilizer, preparation method and application method Download PDF

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Publication number
CN111790353A
CN111790353A CN202010585284.0A CN202010585284A CN111790353A CN 111790353 A CN111790353 A CN 111790353A CN 202010585284 A CN202010585284 A CN 202010585284A CN 111790353 A CN111790353 A CN 111790353A
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humic acid
adsorbent
acid fertilizer
heavy metals
sludge
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陈庆
陈巧和
司文彬
陈涛
白涛
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Chengdu New Keli Chemical Science Co Ltd
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Chengdu New Keli Chemical Science Co Ltd
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
    • B01J20/22—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising organic material
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
    • B01J20/02—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material
    • B01J20/06—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material comprising oxides or hydroxides of metals not provided for in group B01J20/04
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
    • B01J20/28—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof characterised by their form or physical properties
    • B01J20/28002—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof characterised by their form or physical properties characterised by their physical properties
    • B01J20/28009—Magnetic properties
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F11/00—Treatment of sludge; Devices therefor
    • C—CHEMISTRY; METALLURGY
    • C05—FERTILISERS; MANUFACTURE THEREOF
    • C05F—ORGANIC FERTILISERS NOT COVERED BY SUBCLASSES C05B, C05C, e.g. FERTILISERS FROM WASTE OR REFUSE
    • C05F11/00—Other organic fertilisers
    • C05F11/02—Other organic fertilisers from peat, brown coal, and similar vegetable deposits
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J2220/00—Aspects relating to sorbent materials
    • B01J2220/40—Aspects relating to the composition of sorbent or filter aid materials
    • B01J2220/46—Materials comprising a mixture of inorganic and organic materials
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J2220/00—Aspects relating to sorbent materials
    • B01J2220/40—Aspects relating to the composition of sorbent or filter aid materials
    • B01J2220/48—Sorbents characterised by the starting material used for their preparation
    • B01J2220/4806—Sorbents characterised by the starting material used for their preparation the starting material being of inorganic character
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J2220/00—Aspects relating to sorbent materials
    • B01J2220/40—Aspects relating to the composition of sorbent or filter aid materials
    • B01J2220/48—Sorbents characterised by the starting material used for their preparation
    • B01J2220/4812—Sorbents characterised by the starting material used for their preparation the starting material being of organic character
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F2101/00—Nature of the contaminant
    • C02F2101/10—Inorganic compounds
    • C02F2101/20—Heavy metals or heavy metal compounds

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  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Analytical Chemistry (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Hydrology & Water Resources (AREA)
  • Engineering & Computer Science (AREA)
  • Environmental & Geological Engineering (AREA)
  • Water Supply & Treatment (AREA)
  • Inorganic Chemistry (AREA)
  • Fertilizers (AREA)

Abstract

The invention relates to the technical field of magnetic adsorbents, in particular to a preparation method of an adsorbent for removing humic acid fertilizer heavy metals, which comprises the following steps: dispersing the amino modified magnetic particles into a mixed solvent, dropwise adding ethylenediamine tetraacetic dianhydride, stirring for reaction, washing and drying to obtain an EDTA composite magnetic adsorbent; grinding and mixing the EDTA composite magnetic adsorbent and the pore-forming agent, adding the mixture into a granulator, spraying an adhesive, granulating, and drying to obtain the adsorbent with the particle size of 3-4 mm for removing the heavy metal of the humic acid fertilizer. The adsorbent for removing the heavy metals in the humic acid fertilizer is applied to removing the heavy metals in the sludge humic acid fertilizer. The invention solves the problem that the prior art has no magnetic adsorbent for removing heavy metals in sludge. The adsorbent for removing the heavy metals in the humic acid fertilizer is used for removing the heavy metals in the sludge humic acid fertilizer, has good adsorption effect, is easy to separate and is convenient to operate.

Description

Adsorbent for removing heavy metals in humic acid fertilizer, preparation method and application method
Technical Field
The invention relates to the technical field of magnetic adsorbents, in particular to an adsorbent for removing heavy metals in humic acid fertilizers, and a preparation method, application and removal method thereof.
Background
The method for treating domestic garbage includes incineration, composting, landfill and recovery and reuse, and the essence of incineration is to oxidize organic garbage into inert gas and inorganic incombustible under the condition of high temperature and sufficient oxygen supply to form stable solid residue. The composting process utilizes the microorganisms present in the waste to cause biochemical reactions of organic matter to produce a material similar to humic acid soil, which can be used as both a fertilizer and soil improvement. The garbage and the sludge are treated together or the garbage and the excrement are mixed and composted, so that the environmental pollution can be reduced, and the fertilizer efficiency can be improved. Is the most promising household garbage treatment method in developing countries. The landfill method is to directly landfill the garbage, which affects the environment around the garbage landfill pool and is more likely to cause soil pollution. The recycling is to recycle and reuse useful garbage after classifying the garbage, the recycling range of the garbage is small at present, the recycling rate is low, and most of the garbage is treated by other methods.
The composting method takes the garbage as a raw material, and the organic matters in the garbage are subjected to chemical reaction in a composting way, so that the garbage can enter the soil again to be absorbed by crops. The composting method can be divided into aerobic method and anaerobic method according to the decomposition principle, most of the methods adopt high-temperature aerobic method, and the composting method can be divided into open-air composting and mechanical composting according to the stacking method. The mechanical composting period is short, the occupied area is small, the process is simple, and the treatment is easy, so that the mechanical composting method is widely concerned. The fermented domestic garbage can become a substance similar to soil humus, and can be used as a fertilizer and can be used for soil improvement. However, since the domestic garbage contains many harmful substances, such as heavy metals, toxic organic matters and the like, the substances are difficult to remove by simple fermentation treatment, and the purpose of removing the heavy metals by simple acid-base treatment is difficult to achieve due to different adsorption and desorption effects of humic acid on different heavy metals under different pH values, so that a safe, efficient, green and environment-friendly garbage fertilizer can be obtained by using more means.
Humic acids are present in soil, sediments and water and are residues of animal and plant chemical and biological transformations. Humic acid contains various functional groups, mainly including carboxyl, alcoholic hydroxyl, quinonyl, methoxyl, carbonyl and the like, which can chelate mineral ions in soil. The fertilizer containing humic acid has rich organic matters, can fully increase the content of the organic matters in soil and improve the soil fertility. Humic acid is classified into fulvic acid, ulmic acid and fulvic acid according to active ingredients in the humic acid. Wherein, the fulvic acid is a water-soluble substance and is the most important active ingredient in the humic acid. The humic acid fertilizer can improve the soil structure, improve the nutrient utilization rate, stimulate the physiological metabolism of crops, improve the quality of the crops and enhance the stress resistance of the plants.
Chinese patent publication No. CN101723718A discloses a method for producing granular organic fertilizer with high humic acid content by using municipal sludge, which is characterized in that: mixing municipal sludge, dry weathered coal powder and phosphogypsum according to a weight ratio, inoculating 2-4% of total weight of raw materials into enzyme bacteria, fully mixing, entering a fermentation tank, aerating, performing composting fermentation for 10-15 days, then tedding, crushing, adding an organic water-based binder accounting for 0.05-0.1% of the crushed material amount, and granulating. The invention uses high-quality weathered coal powder and straws and organic granulating agents to replace clay as ingredients for aerobic fermentation of municipal sludge, and can greatly improve the quality of granular organic fertilizer. However, since the municipal sludge contains a lot of heavy metals, the sludge is directly fermented, and the heavy metals and toxic substances in the sludge enter the soil again through the fertilizer to pollute the soil, so that the quality of crop products is influenced.
Disclosure of Invention
In view of the above disadvantages of the prior art, the present invention aims to provide a method for preparing an adsorbent for removing heavy metals from humic acid fertilizer, which is used to solve the problem that there is no magnetic adsorbent for removing heavy metals from sludge in the prior art, and at the same time, the present invention also provides an adsorbent for removing heavy metals from humic acid fertilizer; in addition, the invention also provides an application of the absorbent for removing the heavy metal in the humic acid fertilizer in removing the heavy metal in the sludge humic acid fertilizer and a method for removing the heavy metal in the sludge humic acid fertilizer by using the absorbent for removing the heavy metal in the humic acid fertilizer.
In order to attain the above and other related objects,
the invention provides a preparation method of an adsorbent for removing humic acid fertilizer heavy metals, which comprises the following steps:
dispersing magnetic ferroferric oxide nanoparticles into a solvent, adding ammonia water, uniformly stirring, dropwise adding ethyl orthosilicate, stirring for reaction, dropwise adding a silane coupling agent for amino surface modification reaction, and performing magnetic separation to obtain amino modified magnetic particles; the magnetic ferroferric oxide nano particle, the solvent, ammonia water, ethyl orthosilicate and the silane coupling agent are mixed according to the mass ratio of (10-15): (60-80): (3-5): (8-12): (1-2);
dispersing the amino modified magnetic particles into a mixed solvent, dropwise adding ethylenediamine tetraacetic dianhydride, stirring for reaction, washing and drying to obtain an EDTA composite magnetic adsorbent; the mass ratio of the amino modified magnetic particles to the mixed solvent to the ethylenediamine tetraacetic dianhydride is (5-10): (30-40): (3-8);
grinding and mixing the EDTA composite magnetic adsorbent and the pore-forming agent, adding the mixture into a granulator, spraying an adhesive, granulating, and drying to obtain an adsorbent with the particle size of 3-4 mm for removing the heavy metals in the humic acid fertilizer; the weight ratio of the EDTA composite magnetic adsorbent to the pore-forming agent to the adhesive is (20-30): (1-4): (0.1-0.5).
The adsorbent for removing the heavy metals in the humic acid fertilizer is generally a porous granular composite magnetic heavy metal adsorbent which is mainly used for adsorbing the heavy metals.
The magnetic iron tetroxide oxidized particles have large specific surface energy without any surface modification, the particles are easy to agglomerate to form blocks, the particle size is increased, the particles are easy to aggregate due to magnetic attraction and van der Waals force action, and surface modification is usually necessary, so that the reduction of the surface energy of the particles through the surface modification is an important means for obtaining the magnetic nanoparticles with solubility and dispersibility, and meanwhile, the proper surface modification or molecular modification can also adjust the biocompatibility and the stability of the magnetic nanoparticles. Therefore, a protective layer (such as SiO) is coated outside the magnetic ferroferric oxide nano particles2) Therefore, the original magnetism can be kept, the magnetic material is protected from being oxidized or dissolved, and the service life is prolonged. The amino modified magnetic particle prepared in the first step is amino modified magnetic Fe3O4@SiO2Particles.
Formation of amino-modified magnetic Fe by amino modification3O4@SiO2Adding EDTA to modify the amino group of the magnetic Fe3O4@SiO2The particles have more complexing sites, thereby improving the adsorption performance of the particles. And then forming the adsorbent for removing the heavy metal of the humic acid fertilizer by pore-forming with a pore-forming agent. And finally, in the granulation process, the firmness of the whole adsorbent for removing the heavy metal of the humic acid fertilizer is improved by adding the adhesive, and the damage to the whole shape of the adsorbent in the adsorption and stirring process is avoided. Therefore, the adsorbent for removing the heavy metal in the humic acid fertilizer has the advantages of large specific surface area, more complexing sites and stable structure, so that the heavy metal is easy to be subjected to complexing adsorption.
The adsorbent for removing the heavy metal of the humic acid fertilizer has magnetism, so the adsorbent for removing the heavy metal of the humic acid fertilizer is convenient to recycle. In addition, the particle size of the adsorbent for removing the heavy metal in the humic acid fertilizer is controlled to be 3-4 mm, and the adsorbent for removing the heavy metal in the humic acid fertilizer can be separated from an adsorbed substance by the particle size selection principle.
The adsorbent for removing the heavy metal in the humic acid fertilizer has the unique magnetic responsiveness of magnetic ferroferric oxide particles and the small-size effect of ultrafine particles, the silicon dioxide has good biocompatibility and stability, and the silicon dioxide on the surfaces of the ferroferric oxide particles can improve the oxidation resistance of the ferroferric oxide particles and the dispersibility of the particles in a solution.
Further, in the first step, the mass ratio of the magnetic ferroferric oxide nanoparticles to the solvent to the ammonia water to the tetraethoxysilane to the silane coupling agent is (12-14): (65-75): (3-5): (8-12): (1-2);
in the second step, the mass ratio of the amino modified magnetic particles to the mixed solvent to the ethylenediaminetetraacetic dianhydride is (7-8): (30-40): (5-8);
in the third step, the weight ratio of the EDTA composite magnetic adsorbent to the pore-forming agent to the adhesive is (24-26): (2-3): (0.1-0.5).
Formation of amino-modified magnetic Fe by amino modification3O4@SiO2The particle, adsorbent for removing humic acid fertilizer heavy metal is coated with a layer of SiO on the basis of magnetic ferroferric oxide nano particles2The magnetic property of the magnetic ferroferric oxide nano particles is kept, and the adsorbent for removing the heavy metal in the humic acid fertilizer is protected from being oxidized or dissolved, so that the service life is greatly prolonged.
Dropwise adding ethylenediamine tetraacetic dianhydride to modify amino-modified magnetic Fe3O4@SiO2The particles have more complexing sites, thereby improving the adsorption performance of the particles.
A plurality of small holes are formed on the surface of the EDTA composite magnetic adsorbent through the pore-forming agent, so that a porous material is prepared, and the specific surface area of the EDTA composite magnetic adsorbent is improved. The adhesive is sprayed in the granulating process, so that the structure of the formed porous granules is more stable.
Further, the solvent in the first step is water, and the mixed solvent in the second step is acetic acid and ethanol according to a volume ratio of 1: (0.8-1.2) by mixing. The mixed solvent adopted in the second step can improve the compatibility of materials,
Further, in the first step, the silane coupling agent is at least one of KH550, KH560 and KH 570;
the mass fraction of the ammonia water in the first step is 24-26%;
the pore-forming agent in the third step is at least one of ammonium bicarbonate and sodium bicarbonate;
and the adhesive in the third step is polyurethane adhesive.
Further, in the first step, the reaction temperature is 40-70 ℃, the stirring reaction time is 2-4 hours, and the modification reaction time is 1-2 hours;
in the second step, the reaction temperature is 60-80 ℃, and the stirring reaction time is 8-10 h;
in the third step, the drying temperature is 50-60 ℃, and the drying time is 30-60 min.
The adsorbent for removing the heavy metal in the humic acid fertilizer is prepared by any one of the preparation methods.
The adsorbent for removing the heavy metal in the humic acid fertilizer has the unique magnetic responsiveness of magnetic ferroferric oxide particles and the small-size effect of ultrafine particles, the silicon dioxide has good biocompatibility and stability, and the silicon dioxide on the surfaces of the ferroferric oxide particles can improve the oxidation resistance of the ferroferric oxide particles and the dispersibility of the particles in a solution.
The adsorbent for removing the heavy metals in the humic acid fertilizer is applied to removing the heavy metals in the sludge humic acid fertilizer. The adsorbent for removing the heavy metals in the humic acid fertilizer has the unique magnetic responsiveness of magnetic ferroferric oxide particles and the small-size effect of ultrafine particles, and the silicon dioxide has good biocompatibility and stability. The adsorbent for removing the heavy metals in the humic acid fertilizer is used for removing the heavy metals in the sludge humic acid fertilizer, has good adsorption effect, is easy to separate and is convenient to operate.
A method for removing heavy metals in sludge humic acid fertilizer by adopting the adsorbent for removing the heavy metals in the humic acid fertilizer comprises the following steps:
s1, crushing and sieving the sludge humic acid fertilizer, adding the sludge humic acid fertilizer into water for dispersion, adjusting the pH (the pH regulator is phosphoric acid or/and oxalic acid) to 4-5, and then continuously stirring and dispersing to obtain sludge humic acid suspension; wherein the mass ratio of the sludge humic acid fertilizer to water is (5-10): (20-30);
s2, adding the adsorbent for removing the heavy metals in the humic acid fertilizer into the sludge humic acid suspension, and stirring and adsorbing to obtain an adsorbed suspension; the weight ratio of the sludge humic acid suspension to the adsorbent for removing the heavy metals in the humic acid fertilizer is (50-60): (5-10);
s3, adding the suspension liquid after adsorption in the S2 into a reaction kettle with a magnetic stirring rod for stirring, firstly removing the adsorbent for removing the humic acid fertilizer heavy metals by using the magnetic stirring rod, and then screening the particles by using a screening net with the mesh size of 1-2 mm to obtain the adsorbent for removing the humic acid fertilizer heavy metals and the sludge humic acid suspension liquid after adsorption respectively;
and S4, spray drying the sludge humic acid suspension adsorbed in the S3 to obtain the purified sludge humic acid fertilizer.
In the granulating process, the adhesive is added to improve the overall firmness of the absorbent for removing the heavy metal in the humic acid fertilizer, so that the shape of the absorbent for removing the heavy metal in the humic acid fertilizer cannot be damaged in the stirring process. Therefore, the adsorbent for removing the heavy metal in the humic acid fertilizer can be removed after adsorption, so that the adsorbent for removing the heavy metal in the humic acid fertilizer can be recycled.
The adsorbent for removing the heavy metal of the humic acid fertilizer has magnetism, so the adsorbent for removing the heavy metal of the humic acid fertilizer is convenient to recycle. In addition, the particle size of the adsorbent for removing the heavy metal of the humic acid fertilizer is controlled to be 3-4 mm, and the adsorbent for removing the heavy metal of the humic acid fertilizer can be separated from the sludge humic acid fertilizer by the particle size selection principle. Therefore, the adsorbent for removing the heavy metals in the humic acid fertilizer has the advantages of good adsorption effect, thorough separation and reutilization in the process of removing the heavy metals in the sludge humic acid fertilizer.
Heavy metals in sludge humic acid fertilizer are removed by utilizing the adsorbent for removing the heavy metals in the humic acid fertilizer, the EDTA composite adsorbent is complexed with the heavy metals in humic acid, and then the adsorbent for removing the heavy metals in the humic acid fertilizer is separated from the sludge humic acid fertilizer by utilizing magnetism and particle size (by utilizing the easy screening performance and the particle size selection principle of the adsorbent for removing the heavy metals in the humic acid fertilizer), so that the content of the heavy metals in low humic acid is reduced, and the aim of removing the heavy metals is fulfilled.
By utilizing the magnetic selection and particle size selection performance of the magnetic large-particle-size adsorbent, the adsorbent can be conveniently separated from humic acid, and the magnetic particle size selection net is set to be of a magnetic structure, so that the problems of difficult separation caused by blockage of meshes and accumulation of the adsorbent on a grid baffle plate can be effectively prevented, and the aim of removing heavy metals is fulfilled. The method for removing the heavy metal in the sludge humic acid fertilizer by adopting the adsorbent for removing the heavy metal in the humic acid fertilizer has simple process and strong operability, and is suitable for industrial production and application.
The invention utilizes the easy screening performance of the adsorbent for removing the heavy metal of the humic acid fertilizer and the particle size selection principle,
further, the mesh number sieved in the S1 is 200 meshes; the temperature for stirring and dispersing in the S1 is 20-30 ℃, the stirring speed is 100-120 r/min, and the dispersing time is 20-30 min;
the stirring adsorption temperature in the S2 is 30-40 ℃, the stirring speed is 50-60 r/min, and the stirring time is 4-5 h;
in the step S3, the stirring speed is 50-60 r/min, and the stirring time is 10-20 min;
and in the S4, the rotation speed of spray drying is 15000-18000 r/min, the inlet temperature is 140-160 ℃, and the outlet temperature is 70-75 ℃.
Further, the mass ratio of the sludge humic acid fertilizer to the water in the S1 is (7-8): (24-26);
the weight ratio of the sludge humic acid suspension in the S2 to the adsorbent for removing the heavy metals in the humic acid fertilizer is (55-58): (7-8).
As mentioned above, the adsorbent for removing the heavy metals in the humic acid fertilizer, the preparation method, the application and the removal method have the following beneficial effects:
1. by modification of amino groupsThereby forming amino modified magnetic Fe3O4@SiO2Adding EDTA to modify the amino group of the magnetic Fe3O4@SiO2The particles have more complexing sites, thereby improving the adsorption performance of the particles. And then forming the adsorbent for removing the heavy metal of the humic acid fertilizer by pore-forming with a pore-forming agent. And finally, in the granulation process, the firmness of the whole adsorbent for removing the heavy metal of the humic acid fertilizer is improved by adding the adhesive, and the damage to the whole shape of the adsorbent in the adsorption and stirring process is avoided. Therefore, the adsorbent for removing the heavy metal in the humic acid fertilizer has the advantages of large specific surface area, more complexing sites and stable structure, so that the heavy metal is easy to be subjected to complexing adsorption.
2. The adsorbent for removing the heavy metal of the humic acid fertilizer has magnetism, so the adsorbent for removing the heavy metal of the humic acid fertilizer is convenient to recycle. In addition, the particle size of the adsorbent for removing the heavy metal in the humic acid fertilizer is controlled to be 3-4 mm, and the adsorbent for removing the heavy metal in the humic acid fertilizer can be separated from an adsorbed substance by the particle size selection principle.
3. Heavy metals in sludge humic acid fertilizer are removed by utilizing the adsorbent for removing the heavy metals in the humic acid fertilizer, the EDTA composite adsorbent is complexed with the heavy metals in humic acid, and then the adsorbent for removing the heavy metals in the humic acid fertilizer is separated from the sludge humic acid fertilizer by utilizing magnetism and particle size (by utilizing the easy screening performance and the particle size selection principle of the adsorbent for removing the heavy metals in the humic acid fertilizer), so that the content of the heavy metals in low humic acid is reduced, and the aim of removing the heavy metals is fulfilled.
4. By utilizing the magnetic selection and particle size selection performance of the magnetic large-particle-size adsorbent, the adsorbent can be conveniently separated from humic acid, and the magnetic particle size selection net is set to be of a magnetic structure, so that the problems of difficult separation caused by blockage of meshes and accumulation of the adsorbent on a grid baffle plate can be effectively prevented, and the aim of removing heavy metals is fulfilled. The method for removing the heavy metal in the sludge humic acid fertilizer by adopting the adsorbent for removing the heavy metal in the humic acid fertilizer has simple process and strong operability, and is suitable for industrial production and application.
Drawings
FIG. 1 is a flow chart of a method for removing heavy metals in sludge humic acid fertilizer by adopting an adsorbent for removing the heavy metals in the humic acid fertilizer.
FIG. 2 is a bar graph of the heavy metal content of the sludge humic acid fertilizer in comparative example 1, comparative example 2 and example 6 of the invention.
Detailed Description
The present invention will be described in further detail with reference to specific embodiments, but it should not be construed that the scope of the present invention is limited to the following examples. Various substitutions and alterations can be made by those skilled in the art and by conventional means without departing from the spirit of the method of the invention described above.
Example 1
A preparation method of an adsorbent for removing humic acid fertilizer heavy metals comprises the following steps:
dispersing magnetic ferroferric oxide nanoparticles into a solvent (water), adding ammonia water (the mass fraction is 24 percent) and uniformly stirring, dropwise adding tetraethoxysilane and stirring for reaction, dropwise adding a silane coupling agent (KH 550) for amino surface modification reaction, and performing magnetic separation to obtain amino modified magnetic particles (amino modified magnetic Fe)3O4@SiO2Particles); the magnetic ferroferric oxide nano particles, the solvent, ammonia water, ethyl orthosilicate and the silane coupling agent are mixed according to the mass ratio of 10: 60: 3: 8: 1;
dispersing the amino modified magnetic particles into a mixed solvent (obtained by mixing acetic acid and ethanol according to the volume ratio of 1: 0.9), dropwise adding ethylene diamine tetraacetic dianhydride, stirring for reaction, washing and drying to obtain the EDTA composite magnetic adsorbent; wherein the mass ratio of the amino modified magnetic particles to the mixed solvent to the ethylenediamine tetraacetic dianhydride is 5: 30: 3;
grinding and mixing an EDTA (ethylene diamine tetraacetic acid) composite magnetic adsorbent and a pore-forming agent (ammonium bicarbonate), adding the mixture into a granulator, spraying an adhesive (a polyurethane adhesive), granulating, and drying to obtain an adsorbent with the particle size of 3-4 mm for removing humic acid fertilizer heavy metals; wherein the weight ratio of the EDTA composite magnetic adsorbent to the pore-forming agent to the adhesive is 20: 1: 0.1.
specifically, in the first step, the reaction temperature is 40 ℃, the stirring reaction time is 4 hours, and the modification reaction time is 2 hours;
in the second step, the reaction temperature is 60 ℃, and the stirring reaction time is 10 hours;
in the third step, the drying temperature is 50 ℃, and the drying time is 60 min.
The adsorbent for removing the heavy metal in the humic acid fertilizer is prepared by the preparation method.
The application of the adsorbent for removing the heavy metals in the humic acid fertilizer from the sludge comprises the following specific steps:
s1, crushing the sludge humic acid fertilizer, sieving the crushed sludge humic acid fertilizer by a 200-mesh sieve, adding the crushed sludge humic acid fertilizer into water at the temperature of 20 ℃ for dispersion, adjusting the pH to 4, and then continuously stirring and dispersing (the stirring speed is 100r/min, and the dispersion time is 30 min) to obtain sludge humic acid suspension; wherein the mass ratio of the sludge humic acid fertilizer to the water is 5: 20;
s2, adding the adsorbent for removing the heavy metals in the humic acid fertilizer into the sludge humic acid suspension, and stirring for 5 hours at the temperature of 30 ℃ and the stirring speed of 50r/min to obtain the suspension after adsorption; wherein the weight ratio of the sludge humic acid suspension to the adsorbent for removing the heavy metals in the humic acid fertilizer is 50: 5;
s3, adding the suspension liquid after adsorption in the S2 into a reaction kettle with a magnetic stirring rod for stirring (the stirring speed is 50r/min, the stirring time is 20 min), firstly removing the adsorbent for removing the humic acid fertilizer heavy metal by using the magnetic stirring rod, and screening the adsorbent for removing the humic acid fertilizer heavy metal by using a screening net with the mesh size of 1-2 mm at the speed of 1m/S to obtain the adsorbent for removing the humic acid fertilizer heavy metal and the sludge humic acid suspension liquid after adsorption respectively;
and S4, performing spray drying on the sludge humic acid suspension adsorbed in the S3 by a rotating disc atomizer, wherein the rotation speed of the spray drying is 150000r/min, the inlet temperature is 140 ℃, and the outlet temperature is 75 ℃, so that the purified sludge humic acid fertilizer is obtained.
Example 2
A preparation method of an adsorbent for removing humic acid fertilizer heavy metals comprises the following steps:
step one, dispersing magnetic ferroferric oxide nanoparticles into a solvent (water), adding ammonia water (the mass fraction is 26%) to be uniformly stirred, dropwise adding tetraethoxysilane to be stirred for reaction, dropwise adding a silane coupling agent (KH 560) to carry out amino surface modification reaction, and carrying out magnetic separation to obtain amino modified magnetic particles (amino modified magnetic Fe)3O4@SiO2Particles); the mass ratio of the magnetic ferroferric oxide nanoparticles to the solvent to the ammonia water to the ethyl orthosilicate to the silane coupling agent is 15: 80: 5: 12: 2;
dispersing the amino modified magnetic particles into a mixed solvent (obtained by mixing acetic acid and ethanol according to the volume ratio of 1: 1.1), dropwise adding ethylene diamine tetraacetic dianhydride, stirring for reaction, washing and drying to obtain the EDTA composite magnetic adsorbent; wherein the mass ratio of the amino modified magnetic particles to the mixed solvent to the ethylenediamine tetraacetic dianhydride is 10: 40: 8;
grinding and mixing an EDTA (ethylene diamine tetraacetic acid) composite magnetic adsorbent and a pore-forming agent (sodium bicarbonate), adding the mixture into a granulator, spraying an adhesive (a polyurethane adhesive), granulating, and drying to obtain an adsorbent with the particle size of 3-4 mm for removing humic acid fertilizer heavy metals; wherein the weight ratio of the EDTA composite magnetic adsorbent to the pore-forming agent to the adhesive is 30: 4: 0.5.
specifically, in the first step, the reaction temperature is 70 ℃, the stirring reaction time is 2 hours, and the modification reaction time is 1 hour;
in the second step, the reaction temperature is 80 ℃, and the stirring reaction time is 8 hours;
in the third step, the drying temperature is 60 ℃, and the drying time is 30 min.
The adsorbent for removing the heavy metal in the humic acid fertilizer is prepared by the preparation method.
The application of the adsorbent for removing the heavy metals in the humic acid fertilizer from the sludge comprises the following specific steps:
s1, crushing the sludge humic acid fertilizer, sieving the crushed sludge humic acid fertilizer by a 200-mesh sieve, adding the crushed sludge humic acid fertilizer into water at 30 ℃ for dispersion, adjusting the pH to 5, and then continuously stirring and dispersing (the stirring speed is 120r/min, and the dispersion time is 20 min) to obtain sludge humic acid suspension; wherein the mass ratio of the sludge humic acid fertilizer to the water is 10: 30, of a nitrogen-containing gas;
s2, adding the adsorbent for removing the heavy metals in the humic acid fertilizer into the sludge humic acid suspension, and stirring for 4 hours at the temperature of 40 ℃ and the stirring speed of 60r/min to obtain the suspension after adsorption; wherein the weight ratio of the sludge humic acid suspension to the adsorbent for removing the heavy metals in the humic acid fertilizer is 60: 10;
s3, adding the suspension liquid after adsorption in the S2 into a reaction kettle with a magnetic stirring rod for stirring (the stirring speed is 60r/min, the stirring time is 10 min), firstly removing the adsorbent for removing the humic acid fertilizer heavy metal by using the magnetic stirring rod, and screening the adsorbent for removing the humic acid fertilizer heavy metal by using a screening net with the mesh size of 1-2 mm at the speed of 2m/S to obtain the adsorbent for removing the humic acid fertilizer heavy metal and the sludge humic acid suspension liquid after adsorption respectively;
and S4, performing spray drying on the sludge humic acid suspension adsorbed in the S3 by a rotating disc atomizer, wherein the rotation speed of the spray drying is 18000r/min, the inlet temperature is 160 ℃, and the outlet temperature is 75 ℃, so that the purified sludge humic acid fertilizer is obtained.
Example 3
A preparation method of an adsorbent for removing humic acid fertilizer heavy metals comprises the following steps:
step one, dispersing magnetic ferroferric oxide nanoparticles into a solvent (water), adding ammonia water (the mass fraction is 25 percent) and uniformly stirring, dropwise adding tetraethoxysilane and stirring for reaction, dropwise adding a silane coupling agent (KH 570) for amino surface modification reaction, and performing magnetic separation to obtain amino modified magnetic particles (amino modified magnetic Fe)3O4@SiO2Particles); the magnetic ferroferric oxide nano particles, the solvent, ammonia water, ethyl orthosilicate and the silane coupling agent are mixed according to a mass ratio of 12: 65:3：8：1；
dispersing the amino modified magnetic particles into a mixed solvent (obtained by mixing acetic acid and ethanol according to the volume ratio of 1: 1.0), dropwise adding ethylene diamine tetraacetic dianhydride, stirring for reaction, washing and drying to obtain the EDTA composite magnetic adsorbent; wherein the mass ratio of the amino modified magnetic particles to the mixed solvent to the ethylenediamine tetraacetic dianhydride is 7: 30: 5;
grinding and mixing an EDTA (ethylene diamine tetraacetic acid) composite magnetic adsorbent and a pore-forming agent (sodium bicarbonate), adding the mixture into a granulator, spraying an adhesive (a polyurethane adhesive), granulating, and drying to obtain an adsorbent with the particle size of 3-4 mm for removing humic acid fertilizer heavy metals; wherein the weight ratio of the EDTA composite magnetic adsorbent to the pore-forming agent to the adhesive is 24: 2: 0.2.
specifically, in the first step, the reaction temperature is 50 ℃, the stirring reaction time is 3 hours, and the modification reaction time is 1.5 hours;
in the second step, the reaction temperature is 70 ℃, and the stirring reaction time is 9 hours;
in the third step, the drying temperature is 55 ℃, and the drying time is 45 min.
The adsorbent for removing the heavy metal in the humic acid fertilizer is prepared by the preparation method.
The application of the adsorbent for removing the heavy metals in the humic acid fertilizer from the sludge comprises the following specific steps:
s1, crushing the sludge humic acid fertilizer, sieving the crushed sludge humic acid fertilizer by a 200-mesh sieve, adding the crushed sludge humic acid fertilizer into water at 25 ℃ for dispersion, adjusting the pH to 4.6, and then continuously stirring and dispersing (the stirring speed is 110r/min, and the dispersion time is 25 min) to obtain sludge humic acid suspension; wherein the mass ratio of the sludge humic acid fertilizer to the water is 10: 30, of a nitrogen-containing gas;
s2, adding the adsorbent for removing the heavy metals in the humic acid fertilizer into the sludge humic acid suspension, and stirring for 1.5 hours at the temperature of 35 ℃ and the stirring speed of 55r/min to obtain the suspension after adsorption; wherein the weight ratio of the sludge humic acid suspension to the adsorbent for removing the heavy metals in the humic acid fertilizer is 55: 8;
s3, adding the suspension subjected to adsorption in the S2 into a reaction kettle with a magnetic stirring rod, stirring (the stirring speed is 55r/min, the stirring time is 15 min), firstly removing the adsorbent for removing the humic acid fertilizer heavy metals by using the magnetic stirring rod, and screening the adsorbent for removing the humic acid fertilizer heavy metals and the particle size of the adsorbent for removing the humic acid fertilizer heavy metals and the adsorbed sludge humic acid suspension through a screening net with the mesh size of 1-2 mm at the speed of 1.5m/S to obtain the adsorbent for removing the humic acid fertilizer heavy metals and the adsorbed sludge humic acid suspension respectively;
and S4, performing spray drying on the sludge humic acid suspension adsorbed in the S3 by a rotary disc atomizer, wherein the rotation speed of the spray drying is 16000r/min, the inlet temperature is 150 ℃, and the outlet temperature is 72 ℃, so that the purified sludge humic acid fertilizer is obtained.
Example 4
A preparation method of an adsorbent for removing humic acid fertilizer heavy metals comprises the following steps:
dispersing magnetic ferroferric oxide nanoparticles into a solvent (water), adding ammonia water (the mass fraction is 25 percent) and uniformly stirring, dropwise adding tetraethoxysilane and stirring for reaction, dropwise adding a silane coupling agent (KH 550) for amino surface modification reaction, and performing magnetic separation to obtain amino modified magnetic particles (amino modified magnetic Fe)3O4@SiO2Particles); the magnetic ferroferric oxide nano particles, the solvent, ammonia water, ethyl orthosilicate and the silane coupling agent are mixed according to a mass ratio of 14: 75: 5: 12: 2;
dispersing the amino modified magnetic particles into a mixed solvent (obtained by mixing acetic acid and ethanol according to the volume ratio of 1: 1.0), dropwise adding ethylene diamine tetraacetic dianhydride, stirring for reaction, washing and drying to obtain the EDTA composite magnetic adsorbent; wherein the mass ratio of the amino modified magnetic particles to the mixed solvent to the ethylenediamine tetraacetic dianhydride is 8: 40: 8;
grinding and mixing an EDTA (ethylene diamine tetraacetic acid) composite magnetic adsorbent and a pore-forming agent (ammonium bicarbonate), adding the mixture into a granulator, spraying an adhesive (a polyurethane adhesive), granulating, and drying to obtain an adsorbent with the particle size of 3-4 mm for removing humic acid fertilizer heavy metals; wherein the weight ratio of the EDTA composite magnetic adsorbent to the pore-forming agent to the adhesive is (26): 3: 0.5.
specifically, in the first step, the reaction temperature is 60 ℃, the stirring reaction time is 3 hours, and the modification reaction time is 1.5 hours;
in the second step, the reaction temperature is 70 ℃, and the stirring reaction time is 9 hours;
in the third step, the drying temperature is 55 ℃, and the drying time is 40 min.
The adsorbent for removing the heavy metal in the humic acid fertilizer is prepared by the preparation method.
The application of the adsorbent for removing the heavy metals in the humic acid fertilizer from the sludge comprises the following specific steps:
s1, crushing the sludge humic acid fertilizer, sieving the crushed sludge humic acid fertilizer by a 200-mesh sieve, adding the crushed sludge humic acid fertilizer into water at 24 ℃ for dispersion, adjusting the pH to 4.6, and then continuously stirring and dispersing (the stirring speed is 120r/min, and the dispersion time is 30 min) to obtain sludge humic acid suspension; wherein the mass ratio of the sludge humic acid fertilizer to the water is 7: 25;
s2, adding the adsorbent for removing the heavy metals in the humic acid fertilizer into the sludge humic acid suspension, and stirring for 4.5 hours at the temperature of 35 ℃ and the stirring speed of 55r/min to obtain the suspension after adsorption; wherein the weight ratio of the sludge humic acid suspension to the adsorbent for removing the heavy metals in the humic acid fertilizer is 55: 8;
s3, adding the suspension subjected to adsorption in the S2 into a reaction kettle with a magnetic stirring rod, stirring (the stirring speed is 55r/min, the stirring time is 15 min), firstly removing the adsorbent for removing the humic acid fertilizer heavy metals by using the magnetic stirring rod, and screening the adsorbent for removing the humic acid fertilizer heavy metals and the particle size of the adsorbent for removing the humic acid fertilizer heavy metals and the adsorbed sludge humic acid suspension through a screening net with the mesh size of 1-2 mm at the speed of 1.5m/S to obtain the adsorbent for removing the humic acid fertilizer heavy metals and the adsorbed sludge humic acid suspension respectively;
and S4, performing spray drying on the sludge humic acid suspension adsorbed in the S3 by a rotating disc atomizer, wherein the rotation speed of the spray drying is 17000r/min, the inlet temperature is 155 ℃, and the outlet temperature is 73 ℃, so that the purified sludge humic acid fertilizer is obtained.
Example 5
A preparation method of an adsorbent for removing humic acid fertilizer heavy metals comprises the following steps:
dispersing magnetic ferroferric oxide nanoparticles into a solvent (water), adding ammonia water (the mass fraction is 25 percent) and uniformly stirring, dropwise adding tetraethoxysilane and stirring for reaction, dropwise adding a silane coupling agent (KH 550) for amino surface modification reaction, and performing magnetic separation to obtain amino modified magnetic particles (amino modified magnetic Fe)3O4@SiO2Particles); the mass ratio of the magnetic ferroferric oxide nanoparticles to the solvent to the ammonia water to the ethyl orthosilicate to the silane coupling agent is 13: 70: 4: 10: 2;
dispersing the amino modified magnetic particles into a mixed solvent (obtained by mixing acetic acid and ethanol according to the volume ratio of 1: 1.0), dropwise adding ethylene diamine tetraacetic dianhydride, stirring for reaction, washing and drying to obtain the EDTA composite magnetic adsorbent; wherein the mass ratio of the amino modified magnetic particles to the mixed solvent to the ethylenediamine tetraacetic dianhydride is 8: 35: 7;
grinding and mixing an EDTA (ethylene diamine tetraacetic acid) composite magnetic adsorbent and a pore-forming agent (ammonium bicarbonate), adding the mixture into a granulator, spraying an adhesive (a polyurethane adhesive), granulating, and drying to obtain an adsorbent with the particle size of 3-4 mm for removing humic acid fertilizer heavy metals; wherein the weight ratio of the EDTA composite magnetic adsorbent to the pore-forming agent to the adhesive is 25: 3: 0.3.
specifically, in the first step, the reaction temperature is 60 ℃, the stirring reaction time is 3 hours, and the modification reaction time is 1.5 hours;
in the second step, the reaction temperature is 70 ℃, and the stirring reaction time is 9 hours;
in the third step, the drying temperature is 55 ℃, and the drying time is 40 min.
The adsorbent for removing the heavy metal in the humic acid fertilizer is prepared by the preparation method.
The application of the adsorbent for removing the heavy metals in the humic acid fertilizer from the sludge comprises the following specific steps:
s1, crushing the sludge humic acid fertilizer, sieving the crushed sludge humic acid fertilizer by a 200-mesh sieve, adding the crushed sludge humic acid fertilizer into water at 24 ℃ for dispersion, adjusting the pH to 4.6, and then continuously stirring and dispersing (the stirring speed is 120r/min, and the dispersion time is 30 min) to obtain sludge humic acid suspension; wherein the mass ratio of the sludge humic acid fertilizer to the water is 8: 26;
s2, adding the adsorbent for removing the heavy metals in the humic acid fertilizer into the sludge humic acid suspension, and stirring for 4.5 hours at the temperature of 35 ℃ and the stirring speed of 55r/min to obtain the suspension after adsorption; wherein the weight ratio of the sludge humic acid suspension to the adsorbent for removing the heavy metals in the humic acid fertilizer is 56: 7;
s3, adding the suspension subjected to adsorption in the S2 into a reaction kettle with a magnetic stirring rod, stirring (the stirring speed is 55r/min, the stirring time is 15 min), firstly removing the adsorbent for removing the humic acid fertilizer heavy metals by using the magnetic stirring rod, and screening the adsorbent for removing the humic acid fertilizer heavy metals and the particle size of the adsorbent for removing the humic acid fertilizer heavy metals and the adsorbed sludge humic acid suspension through a screening net with the mesh size of 1-2 mm at the speed of 1.5m/S to obtain the adsorbent for removing the humic acid fertilizer heavy metals and the adsorbed sludge humic acid suspension respectively;
and S4, performing spray drying on the sludge humic acid suspension adsorbed in the S3 by a rotating disc atomizer, wherein the rotation speed of the spray drying is 17000r/min, the inlet temperature is 155 ℃, and the outlet temperature is 73 ℃, so that the purified sludge humic acid fertilizer is obtained.
Example 6
A preparation method of an adsorbent for removing humic acid fertilizer heavy metals comprises the following steps:
dispersing magnetic ferroferric oxide nanoparticles into a solvent (water), adding ammonia water (the mass fraction is 25 percent) and uniformly stirring, dropwise adding tetraethoxysilane and stirring for reaction, dropwise adding a silane coupling agent (KH 550) for amino surface modification reaction, and performing magnetic separation to obtain amino modified magnetic particles (amino modified magnetic Fe)3O4@SiO2Particles); the mass ratio of the magnetic ferroferric oxide nanoparticles to the solvent to the ammonia water to the ethyl orthosilicate to the silane coupling agent is 13: 72: 4: 11: 2;
dispersing the amino modified magnetic particles into a mixed solvent (obtained by mixing acetic acid and ethanol according to the volume ratio of 1: 1.0), dropwise adding ethylene diamine tetraacetic dianhydride, stirring for reaction, washing and drying to obtain the EDTA composite magnetic adsorbent; wherein the mass ratio of the amino modified magnetic particles to the mixed solvent to the ethylenediamine tetraacetic dianhydride is 7: 35: 6;
grinding and mixing an EDTA (ethylene diamine tetraacetic acid) composite magnetic adsorbent and a pore-forming agent (ammonium bicarbonate), adding the mixture into a granulator, spraying an adhesive (a polyurethane adhesive), granulating, and drying to obtain an adsorbent with the particle size of 3-4 mm for removing humic acid fertilizer heavy metals; wherein the weight ratio of the EDTA composite magnetic adsorbent to the pore-forming agent to the adhesive is 25: 3: 0.4.
specifically, in the first step, the reaction temperature is 60 ℃, the stirring reaction time is 3 hours, and the modification reaction time is 1.5 hours;
in the second step, the reaction temperature is 70 ℃, and the stirring reaction time is 9 hours;
in the third step, the drying temperature is 55 ℃, and the drying time is 40 min.
The adsorbent for removing the heavy metal in the humic acid fertilizer is prepared by the preparation method.
The application of the adsorbent for removing the heavy metals in the humic acid fertilizer from the sludge comprises the following specific steps:
s1, crushing the sludge humic acid fertilizer, sieving the crushed sludge humic acid fertilizer by a 200-mesh sieve, adding the crushed sludge humic acid fertilizer into water at 24 ℃ for dispersion, adjusting the pH to 4.6, and then continuously stirring and dispersing (the stirring speed is 120r/min, and the dispersion time is 30 min) to obtain sludge humic acid suspension; wherein the mass ratio of the sludge humic acid fertilizer to the water is 8: 25;
s2, adding the adsorbent for removing the heavy metals in the humic acid fertilizer into the sludge humic acid suspension, and stirring for 4.5 hours at the temperature of 35 ℃ and the stirring speed of 55r/min to obtain the suspension after adsorption; wherein the weight ratio of the sludge humic acid suspension to the adsorbent for removing the heavy metals in the humic acid fertilizer is 56: 8;
s3, adding the suspension subjected to adsorption in the S2 into a reaction kettle with a magnetic stirring rod, stirring (the stirring speed is 55r/min, the stirring time is 15 min), firstly removing the adsorbent for removing the humic acid fertilizer heavy metals by using the magnetic stirring rod, and screening the adsorbent for removing the humic acid fertilizer heavy metals and the particle size of the adsorbent for removing the humic acid fertilizer heavy metals and the adsorbed sludge humic acid suspension through a screening net with the mesh size of 1-2 mm at the speed of 1.5m/S to obtain the adsorbent for removing the humic acid fertilizer heavy metals and the adsorbed sludge humic acid suspension respectively;
and S4, performing spray drying on the sludge humic acid suspension adsorbed in the S3 by a rotating disc atomizer, wherein the rotation speed of the spray drying is 17000r/min, the inlet temperature is 155 ℃, and the outlet temperature is 73 ℃, so that the purified sludge humic acid fertilizer is obtained.
Comparative example 1
Sludge humic acid fertilizer which is not treated. Compared with the difference of the embodiment 6, the sludge humic acid fertilizer in the embodiment 1 does not remove heavy metals by the adsorbent for removing the heavy metals of the humic acid fertilizer. The sludge humic acid fertilizer in the comparative example 1 and the sludge humic acid fertilizers adopted in the examples 1 to 6 and the comparative example 2 are sludge humic acid fertilizers of the same batch.
Comparative example 2
A preparation method of an adsorbent for removing humic acid fertilizer heavy metals comprises the following steps:
dispersing magnetic ferroferric oxide nanoparticles into a solvent (water), adding ammonia water (the mass fraction is 25 percent) and uniformly stirring, dropwise adding tetraethoxysilane and stirring for reaction, dropwise adding a silane coupling agent (KH 550) for amino surface modification reaction, and performing magnetic separation to obtain amino modified magnetic particles (amino modified magnetic Fe)3O4@SiO2Particles); the mass ratio of the magnetic ferroferric oxide nanoparticles to the solvent to the ammonia water to the ethyl orthosilicate to the silane coupling agent is 13: 72: 4: 11: 2;
dispersing the amino modified magnetic particles into a mixed solvent (obtained by mixing acetic acid and ethanol according to the volume ratio of 1: 1.0), dropwise adding ethylene diamine tetraacetic dianhydride, stirring for reaction, washing and drying to obtain the EDTA composite magnetic adsorbent; wherein the mass ratio of the amino modified magnetic particles to the mixed solvent to the ethylenediamine tetraacetic dianhydride is 7: 35: 6;
adding the EDTA composite magnetic adsorbent into a granulator, spraying an adhesive (polyurethane adhesive), granulating, and drying to obtain an adsorbent with the particle size of 3-4 mm for removing the heavy metals in the humic acid fertilizer; wherein the weight ratio of the EDTA composite magnetic adsorbent to the adhesive is 25: 0.4.
Specifically, in the first step, the reaction temperature is 60 ℃, the stirring reaction time is 3 hours, and the modification reaction time is 1.5 hours;
in the second step, the reaction temperature is 70 ℃, and the stirring reaction time is 9 hours;
in the third step, the drying temperature is 55 ℃, and the drying time is 40 min.
The adsorbent for removing the heavy metal in the humic acid fertilizer is prepared by the preparation method.
The application of the adsorbent for removing the heavy metals in the humic acid fertilizer from the sludge comprises the following specific steps:
s1, crushing the sludge humic acid fertilizer, sieving the crushed sludge humic acid fertilizer by a 200-mesh sieve, adding the crushed sludge humic acid fertilizer into water at 24 ℃ for dispersion, adjusting the pH to 4.6, and then continuously stirring and dispersing (the stirring speed is 120r/min, and the dispersion time is 30 min) to obtain sludge humic acid suspension; wherein the mass ratio of the sludge humic acid fertilizer to the water is 8: 25;
s2, adding the adsorbent for removing the heavy metals in the humic acid fertilizer into the sludge humic acid suspension, and stirring for 4.5 hours at the temperature of 35 ℃ and the stirring speed of 55r/min to obtain the suspension after adsorption; wherein the weight ratio of the sludge humic acid suspension to the adsorbent for removing the heavy metals in the humic acid fertilizer is 56: 8;
s3, adding the suspension subjected to adsorption in the S2 into a reaction kettle with a magnetic stirring rod, stirring (the stirring speed is 55r/min, the stirring time is 15 min), firstly removing the adsorbent for removing the humic acid fertilizer heavy metals by using the magnetic stirring rod, and screening the adsorbent for removing the humic acid fertilizer heavy metals and the particle size of the adsorbent for removing the humic acid fertilizer heavy metals and the adsorbed sludge humic acid suspension through a screening net with the mesh size of 1-2 mm at the speed of 1.5m/S to obtain the adsorbent for removing the humic acid fertilizer heavy metals and the adsorbed sludge humic acid suspension respectively;
and S4, performing spray drying on the sludge humic acid suspension adsorbed in the S3 by a rotating disc atomizer, wherein the rotation speed of the spray drying is 17000r/min, the inlet temperature is 155 ℃, and the outlet temperature is 73 ℃, so that the purified sludge humic acid fertilizer is obtained.
Comparative example 2 is different from example 6 in that comparative example 2 is the same as example 6 except that a large-particle EDTA composite adsorbent prepared by adding a pore-forming agent is not used.
The sludge humic acid fertilizers treated in the examples 1 to 6 and the comparative example 2 and the sludge humic acid fertilizer in the comparative example 1 are tested as follows, and the test results are shown in table 1:
the sludge humic acid fertilizer in the comparative example 1 and the sludge humic acid fertilizers adopted in the examples 1 to 6 and the comparative example 2 are sludge humic acid fertilizers of the same batch.
And (4) testing standard: the fertilizers of the examples and comparative examples were tested for heavy metal content with reference to the method and requirements of the agricultural sludge contaminant control standard (GB 4284-2018).
The test method comprises the following steps: weighing 1g of each of the sludge humic acid fertilizers treated in the embodiments 1-6 and the comparative example 2 and the sludge humic acid fertilizer in the comparative example 1, respectively adding the sludge humic acid fertilizers into a digestion bottle, adding 10ml of nitric acid, heating to 90 ℃ for refluxing for 15 minutes, continuously dropwise adding 5ml of nitric acid for continuously refluxing until no brown smoke appears, cooling, adding 2ml of water and 3ml of 30% hydrogen peroxide, slowly heating, continuously dropwise adding 1ml of 30% hydrogen peroxide until the appearance of a sample is unchanged, continuously heating until the volume is reduced to 5ml, carrying out centrifugal separation, adding water to a constant volume of 100ml, and obtaining a liquid to be detected. And (3) measuring the contents of heavy metals of chromium, lead, nickel and copper in the liquid to be measured by adopting an inductively coupled plasma mass spectrometer.
Table form
Figure DEST_PATH_IMAGE002
Group of Cadmium/(mg/kg) Lead/(mg/kg) Nickel/(mg/kg) Copper/(mg/kg)
Example 1 465 263 90 445
Example 2 468 262 89 446
Example 3 462 259 89 439
Example 4 460 258 88 437
Example 5 458 259 88 436
Example 6 452 256 87 431
Comparative example 1 642 340 114 768
Comparative example 2 511 287 88 592
The comparative example 1 is equivalent to a blank control, and therefore, the heavy metal content in the sludge humic acid fertilizer treated in the examples 1 to 6 is obviously reduced, and the heavy metal content in soil can be reduced when the sludge humic acid fertilizer is used for production, so that the soil fertility is improved, and meanwhile, too much heavy metal cannot be introduced. In comparative example 2, no pore-forming agent was added, so the adsorption strength to heavy metals was weaker than in examples 1 to 6.
The sludge humic acid fertilizer of the comparative example 1 has high heavy metal content, belongs to B-grade sludge products by referring to agricultural sludge pollutant control standards (GB 4284-2018), and is suitable for farmlands in gardens, pasturing fields and without planting edible crops.
The heavy metal content in the sludge humic acid fertilizer treated by the comparative example 2 is reduced, but the cadmium and copper content is still higher than the standard that the agricultural sludge pollutant control standard is less than 500mg/kg, and the treated sludge humic acid fertilizer still belongs to a B-grade sludge product.
The sludge humic acid fertilizer treated by the embodiments 1 to 6 has the heavy metal content reduced below the standard of A-grade sludge products (less than 500 mg/kg), and can be used for agricultural farmlands, garden lands and the like. Therefore, the invention can improve the removal effect of heavy metals in sludge humic acid after the granular composite magnetic adsorbent is subjected to porous treatment, and meanwhile, the removal process is simple and efficient, and is suitable for large-scale production.
Fig. 1 is a bar chart of heavy metal content of the sludge humic acid fertilizer in comparative example 1, comparative example 2 and example 6 (data source is table 1), which more intuitively shows the difference of the heavy metal content of the sludge humic acid fertilizer and the heavy metal content of the sludge humic acid fertilizer.
In conclusion, the adsorbent material (EDTA composite magnetic adsorbent) is granulated and is convenient to separate, and the pore-forming performance of the pore-forming agent is utilized to enable the granulated adsorbent to be of a porous structure, so that more effective EDTA complexing sites are arranged on the adsorbent; meanwhile, the magnetic property of the adsorbent is adhered to the magnetic stirring rod, so that most of the adsorbent can be removed, the problem that humic acid is difficult to separate due to the fact that meshes of the adsorbent are blocked in the screening process is effectively solved, the adsorbent can be conveniently separated from sludge humic acid through double separation of the magnetic property and the particle size, and the purpose of removing heavy metals can be achieved more easily. Therefore, the invention effectively overcomes various defects in the prior art and has high industrial utilization value.
The foregoing embodiments are merely illustrative of the principles and utilities of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or change the above-mentioned embodiments without departing from the spirit and scope of the present invention. Accordingly, it is intended that all equivalent modifications or changes which can be made by those skilled in the art without departing from the spirit and technical spirit of the present invention be covered by the claims of the present invention.

Claims (10)

1. The preparation method of the adsorbent for removing the heavy metals in the humic acid fertilizer is characterized by comprising the following steps of:
dispersing magnetic ferroferric oxide nanoparticles into a solvent, adding ammonia water, uniformly stirring, dropwise adding ethyl orthosilicate, stirring for reaction, dropwise adding a silane coupling agent for amino surface modification reaction, and performing magnetic separation to obtain amino modified magnetic particles; the magnetic ferroferric oxide nano particle, the solvent, ammonia water, ethyl orthosilicate and the silane coupling agent are mixed according to the mass ratio of (10-15): (60-80): (3-5): (8-12): (1-2);
dispersing the amino modified magnetic particles into a mixed solvent, dropwise adding ethylenediamine tetraacetic dianhydride, stirring for reaction, washing and drying to obtain an EDTA composite magnetic adsorbent; the mass ratio of the amino modified magnetic particles to the mixed solvent to the ethylenediamine tetraacetic dianhydride is (5-10): (30-40): (3-8);
grinding and mixing the EDTA composite magnetic adsorbent and the pore-forming agent, adding the mixture into a granulator, spraying an adhesive, granulating, and drying to obtain an adsorbent with the particle size of 3-4 mm for removing the heavy metals in the humic acid fertilizer; the weight ratio of the EDTA composite magnetic adsorbent to the pore-forming agent to the adhesive is (20-30): (1-4): (0.1-0.5).
2. The preparation method of the adsorbent for removing the heavy metals in the humic acid fertilizer according to claim 1, which is characterized by comprising the following steps: in the first step, the mass ratio of the magnetic ferroferric oxide nanoparticles to the solvent to the ammonia water to the tetraethoxysilane to the silane coupling agent is (12-14): (65-75): (3-5): (8-12): (1-2);
in the second step, the mass ratio of the amino modified magnetic particles to the mixed solvent to the ethylenediaminetetraacetic dianhydride is (7-8): (30-40): (5-8);
in the third step, the weight ratio of the EDTA composite magnetic adsorbent to the pore-forming agent to the adhesive is (24-26): (2-3): (0.1-0.5).
3. The preparation method of the adsorbent for removing the heavy metals in the humic acid fertilizer according to claim 1 or 2, which is characterized by comprising the following steps: the solvent in the first step is water, and the mixed solvent in the second step is acetic acid and ethanol according to a volume ratio of 1: (0.8-1.2) by mixing.
4. The preparation method of the adsorbent for removing the heavy metals in the humic acid fertilizer according to claim 1 or 2, which is characterized by comprising the following steps: in the first step, the silane coupling agent is at least one of KH550, KH560 and KH 570;
the mass fraction of the ammonia water in the first step is 24-26%;
the pore-forming agent in the third step is at least one of ammonium bicarbonate and sodium bicarbonate;
and the adhesive in the third step is polyurethane adhesive.
5. The preparation method of the adsorbent for removing the heavy metals in the humic acid fertilizer according to claim 1 or 2, which is characterized by comprising the following steps: in the first step, the reaction temperature is 40-70 ℃, the stirring reaction time is 2-4 h, and the modification reaction time is 1-2 h;
in the second step, the reaction temperature is 60-80 ℃, and the stirring reaction time is 8-10 h;
in the third step, the drying temperature is 50-60 ℃, and the drying time is 30-60 min.
6. An adsorbent for removing humic acid fertilizer heavy metals, which is prepared by the preparation method according to any one of claims 1 to 5.
7. The use of the adsorbent for removing heavy metals in humic acid fertilizer as claimed in claim 6 in removing heavy metals in sludge humic acid fertilizer.
8. The method for removing the heavy metals in the sludge humic acid fertilizer by using the absorbent for removing the heavy metals in the humic acid fertilizer as claimed in claim 6 is characterized by comprising the following steps:
s1, crushing and sieving the sludge humic acid fertilizer, adding the sludge humic acid fertilizer into water for dispersion, adjusting the pH to 4-5, and continuously stirring and dispersing to obtain sludge humic acid suspension; wherein the mass ratio of the sludge humic acid fertilizer to water is (5-10): (20-30);
s2, adding the absorbent for removing humic acid fertilizer heavy metals as in claim 6 into the sludge humic acid suspension, and stirring and adsorbing to obtain the suspension after adsorption; the weight ratio of the sludge humic acid suspension to the adsorbent for removing the heavy metals in the humic acid fertilizer is (50-60): (5-10);
s3, adding the suspension liquid after adsorption in the S2 into a reaction kettle with a magnetic stirring rod for stirring, firstly removing the adsorbent for removing the humic acid fertilizer heavy metals by using the magnetic stirring rod, and then screening the particles by using a screening net with the mesh size of 1-2 mm to obtain the adsorbent for removing the humic acid fertilizer heavy metals and the sludge humic acid suspension liquid after adsorption respectively;
and S4, spray drying the sludge humic acid suspension adsorbed in the S3 to obtain the purified sludge humic acid fertilizer.
9. The method for removing the heavy metals in the sludge humic acid fertilizer by adopting the adsorbent for removing the heavy metals in the humic acid fertilizer according to claim 8, is characterized in that: the mesh number sieved in the S1 is 200 meshes; the temperature for stirring and dispersing in the S1 is 20-30 ℃, the stirring speed is 100-120 r/min, and the dispersing time is 20-30 min;
the stirring adsorption temperature in the S2 is 30-40 ℃, the stirring speed is 50-60 r/min, and the stirring time is 4-5 h;
in the step S3, the stirring speed is 50-60 r/min, and the stirring time is 10-20 min;
and in the S4, the rotation speed of spray drying is 15000-18000 r/min, the inlet temperature is 140-160 ℃, and the outlet temperature is 70-75 ℃.
10. The method for removing the heavy metals in the sludge humic acid fertilizer by adopting the adsorbent for removing the heavy metals in the humic acid fertilizer according to claim 8 or 9, which is characterized by comprising the following steps: the mass ratio of the sludge humic acid fertilizer to the water in the S1 is (7-8): (24-26);
the weight ratio of the sludge humic acid suspension in the S2 to the adsorbent for removing the heavy metals in the humic acid fertilizer is (55-58): (7-8).
CN202010585284.0A 2020-06-24 2020-06-24 Adsorbent for removing heavy metals in humic acid fertilizer, preparation method and application method Withdrawn CN111790353A (en)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN112403451A (en) * 2020-11-11 2021-02-26 湖南长重机器股份有限公司 Porous sludge dye adsorbent and preparation method thereof

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN112403451A (en) * 2020-11-11 2021-02-26 湖南长重机器股份有限公司 Porous sludge dye adsorbent and preparation method thereof

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Application publication date: 20201020