CN103787443B - Flow-Through Adsorber for Total Dissolved Solids Removal - Google Patents

Abstract

A flow-through adsorber for removing total dissolved solids is disclosed. A seawater stock solution containing a large amount of Total Dissolved Solids (TDS) is passed Through a Flow Through Adsorber (FTA) containing an adsorbent material, the TDS of the seawater is substantially removed at once without energizing the adsorbent material. Many substances can be used to make the adsorbent materials with bifunctional functional groups used in the above-mentioned FTA. One of the bifunctional functional groups of the adsorbent comes from a cation-adsorbing atomic group imparted by phosphorylation (phosphorylation), and the other comes from an anion-adsorbing atomic group generated by amination. The adsorbent material may be in the form of a permeable membrane or a packed bed, depending on the application. When the adsorbent material is saturated, on-line regeneration can be performed using a liquid having a lower TDS than the liquid being treated. In addition to seawater, the present invention can treat other waste waters that are plagued by TDS at a very low cost.

Description

Flow-Through Adsorber for Total Dissolved Solids Removal

technical field

The present invention relates to a Flow Through Adsorber (Flow Through Adsorber, FTA), which removes Total Dissolved Solids (TDS) in water by means of a non-energized ion absorption process. Taking seawater as an example, its TDS drops sharply as soon as the seawater comes into contact with the adsorbent in FTA. In particular, adsorbents converted from agricultural waste or biomass materials can effectively and inexpensively remove TDS from water and various liquids.

Background technique

TDS is a common pollutant of all wastewater including seawater. In the process of desalinating seawater into drinking water, the removal of TDS is the main goal and the most difficult item to deal with. Currently, reverse osmosis (Reverse Osmosis, RO) and distillation are the two most commonly used desalination technologies for removing TDS from seawater. Many solids dissolve in water and decompose into ions. Through the rapid attraction of positive and negative charges, ions are easily attracted by the electrostatic field to achieve the effect of desalination. Capacitive deionization CDI (Capacitive Deionization) technology uses the principle of positive and negative charges to attract each other to desalinate seawater with a flow-through capacitor FTC (Flow Through Capacitor). The inventor of the present invention has devoted himself to the development of CDI technology for more than ten years, and obtained several US patents, for example, US Patent Nos. 6,462,935 and 6,795,298. CDI can be an effective replacement technology for RO and distillation, because CDI has the characteristics of "no chemicals, high water recovery rate, low energy consumption, and direct recovery and storage of electric energy used for ion absorption". However, CDI technology also has some defects, including: using high-priced titanium metal as the substrate of FTC electrodes, automatic regeneration of FTC electrodes with expensive electronic control, and the most serious problem of "low productivity and short life of FTC electrodes".

In the literature, there are many reports on "reducing the TDS and COD (Chemical Oxygen Demand) of water through the adsorption process with cheap adsorbents without electricity". For example, US Pat. No. 4,877,534 and No. 7,727,398 use charred rice to absorb organic pollutants and dyes in water. US Patent Nos. 6,579,977 and 7,098,327 convert agricultural waste into carbonaceous adsorbents for the removal of heavy metals in water. Yabusaki, in US Patent No. 7,803,937, discloses the technology of softening tap water with cabamidated cotton. In addition, in "Journal of Environmental Science and Technology" (Journal of Environmental Science and Technology), No. 1 (3), pp. 124-134 (2008), Lori et al. disclosed that activated carbon was made from crop stems for absorbing Dye in water. Shareef reviewed a series of biomass materials (biomass materials) and industrial wastes through carbonization and activation in "World Journal of Agricultural Science", No. 5 (S), 819-831 (2009). Formation of adsorbents to remove various heavy metals from water. The above-mentioned U.S. patents and periodical papers are all used as reference data of the present invention.

Due to the huge surface area, high density of pores and various surface functional groups, the water treatment industry widely uses activated carbon as a filter material to remove many pollutants in water, but does not include the removal of TDS. However, the previous section reveals that many natural and artificial products can be made into carbonized adsorbents through low temperature and mild drugs through a more economical process than the current industrial production method of activated carbon. At the same time, these waste-derived sorbents outperform commercial activated carbons in many water treatment applications. Almost all carbon-containing substances can be made into carbonized adsorbents, for example: sewage sludge, shells of grains and drupes, lignocellulosic waste, petroleum waste, and industrial waste such as tires and rubber, etc., can be used as carbonized raw material for the adsorbent. In "Recent Patents on Chemical Engineering", No. 1, pp. 27-40, (2008), Shen et al. summarized eight processes for surface modification of the above-mentioned waste and activated carbon. After surface modification, the original surface functional groups of waste and activated carbon are changed to become atomic groups of waste that can remove special pollutants in water, and activated carbon has a new water treatment function. Examples of activated carbon surface modification designed for water treatment and other applications can be found in US Pat.

The present invention found that among all chemical reactions for surface modification, phosphorylation and amination are the most effective for removing TDS in water. The former can generate atomic groups for adsorbing cations, and the latter can provide atomic groups for adsorbing anions. Sequentially applying "cationization" and "anionization" to a carbonaceous adsorbent raw material can make the raw material an "ambivalent functional group adsorbent", as disclosed in US Patent No. 7,098,327. However, No. 7,098,327 and all other literatures on adsorption water treatment do not have a solution for reducing TDS in a large amount for wastewater with high TDS level, such as seawater, brine, production line and underground brine. In addition, all the old processes have not proposed the implementation technology of regenerating the adsorbent on-line so that it can operate continuously. The present invention proposes a flow-through adsorber FTA made of a permeable membrane or packed bed of "activated carbon with amphoteric functional group", or a packed bed of "carbonized rice husk with amphipathic functional group", which can continuously Desalinate large quantities of seawater, or soften large quantities of tap water. When the adsorbent is saturated, it can be regenerated quickly and repeatedly online with tap water, deionized water, surface water or seawater with a lower TDS than the treated water.

Contents of the invention

One of the projects of the present invention is to produce "ambivalent functional group activated carbon" for seawater desalination with the least amount of chemicals, the lowest reaction temperature and the shortest reaction time. In order to simultaneously remove cations and anions in seawater, activated carbon particles must have amphoteric functional groups. Therefore, the selected powder or granular activated carbon must be chemically treated by phosphorylation and amination, and the phosphorylation is carried out first. In non-biochemical phosphorylation, phosphoric acid (H ₃ PO ₄ ) is the main agent, but diammonium hydrogen phosphate [(NH ₄ ) ₂ HPO ₄ ] and urea can be used as auxiliary agents. Phosphorylation of activated carbon can generally be carried out in a mixture of activated carbon and the above-mentioned agents under air at 140°C to 200°C for 1 to 3 hours. On the other hand, there are many options for the ammonization agent of activated carbon, including: ammonia gas, ammonia water, linear and aromatic amines, heterocyclic amines, and ammonium alkalis and salts. The ammonification of activated carbon can generally be carried out at 45°C to 100°C for 6 to 12 hours. Since the reaction temperature of ammonification is low, it is carried out after phosphorylation. Activated carbon after phosphorylation must be washed with water to remove the agent and then ammonized. After ammonification, the ammonium activated carbon must be washed to remove the drug, and finally vacuum-dried to be stored for future use.

Powdered or granular activated carbon products are widely used in water treatment, but the price is high. The second project of the present invention is to reduce the cost of water treatment by using various agricultural wastes as substitutes for activated carbon. The present invention examines some agricultural wastes native to Taiwan, China, and selects rice husks as raw materials for alternative adsorbents of activated carbon. Without any processing, the rice husk is directly phosphorylated by activated carbon, except for the temperature, and carbonized at 200-500°C, so that the brown rice husk turns black. After the rice husk charcoal is washed, it is treated with the ammonization condition of activated carbon, and then becomes "rice husk charcoal with amphoteric functional group".

The best way to implement granular "amphirofunctional activated carbon" and "ampiofunctional rice husk charcoal" for water treatment is to be installed in a container as a "packed bed" FTA. However, if the powdered "amphirofunctional activated carbon" is also made into a packed bed, water will not flow easily. Therefore, the third item of the present invention is to make the best design of FTA for powdery "amphiteric functional group activated carbon". The present invention proposes three methods for fixing powdery "activated carbon with amphoteric functional groups": (1) "activated carbon with amphoteric functional groups" powder is mixed with an adhesive and a solvent to form a slurry, which is then sprayed and dried and fixed on a mesh (2) Add a certain amount of "amphipotent functional group activated carbon" powder to a molten plastic and mix evenly, and roll to form a permeable film; (3) Activated carbon The prepared porous blanket is chemically treated with phosphorylation and ammonium to become an amphoteric functional group permeable blanket. Because the active carbon contained in the permeable membrane and the permeable blanket is integrated with the plastic, the activated carbon is less likely to fall off than the powder attached to the surface of the permeable net. At the same time, the integrally formed product has a three-dimensional structure, and the ion removal rate per unit weight of the adsorbent is also higher than that of the two-dimensional mesh. However, the production cost of 2D permeable mesh is lower than that of 3D products.

According to the fourth aspect of the present invention, an activated carbon permeable net or an activated carbon permeable membrane is placed in a container to form FTA. After the activated carbon permeable net or activated carbon permeable membrane is folded into an accordion form, and then stuffed into a plastic container with water flow, it becomes an independent flow-through adsorber FTA cassette. The amount of water treated by an FTA cassette is proportional to the area of activated carbon placed in the FTA cassette, and the area of a folded accordion is not as large as that of a coiled accordion. Therefore, a rectangular activated carbon permeable net, or a rectangular activated carbon permeable membrane, with a water inlet pipe as the center, is wound clockwise into a spiral coil, which can provide the largest activated carbon area with the smallest volume . The flow of treated water in the FTA cassette is perpendicular to the surface of the activated carbon permeable mesh or activated carbon permeable membrane, uniformly passes through the activated carbon mesh or activated carbon membrane, and then flows out of the FTA cassette. When the water to be treated is in contact with the activated carbon of the amphoteric functional group when it passes through the spiral coil, the charged substances in the water will be adsorbed. When the FTA's adsorbent is saturated due to seawater treatment, the adsorbent can be regenerated immediately by flowing tap water with the capacity of one FTA cartridge. Whether FTA cassettes use packed beds, permeable mesh, or permeable membranes, their cycles of ion adsorption and ion desorption are rapid and reversible.

The advantages and spirit of the present invention can be further understood through the following detailed description of the invention and the accompanying drawings.

Description of drawings

Figure 1 shows the process flow of the production method of activated carbon with amphoteric functional groups, wherein the activated carbon is first subjected to phosphorylation, so that the surface of the activated carbon is planted with atomic groups that adsorb cations. Next, the activated carbon is ammonized again, so that the surface of the activated carbon obtains atomic groups for adsorbing anions.

Fig. 2 shows the process flow of the manufacturing method of the activated carbon permeable net, wherein the amphoteric functional group activated carbon is sprayed and attached to a plastic net to become the permeable net. After the activated carbon is folded into an accordion form through the net, it is stuffed into a plastic container through which water can circulate, and becomes a flow-through adsorber FTA unit for removing TDS. The arrows in the figure indicate the flow of treated water in the FTA unit, perpendicular to the surface of the activated carbon permeation mesh.

Figure 3 shows the production of activated carbon permeable mesh or activated carbon permeable membrane to form a spiral roll, in which a rectangular activated carbon permeable net or a rectangular activated carbon permeable membrane is centered on a porous water inlet pipe. Wrapped into a spiral roll.

Figure 4 shows the feasibility of desalinating seawater with activated carbon with amphoteric functional groups through the net, where the ordinate is the TDS of seawater, and the abscissa is the number of cycles of ion adsorption and ion desorption. With the increase of the number of cycles, the TDS of seawater gradually decreased.

Fig. 5 shows the feasibility of desalinating seawater with activated carbon with amphoteric functional groups permeating the membrane, where the ordinate is the TDS of seawater, and the abscissa is the number of cycles of ion adsorption and ion desorption. The permeable membrane in Fig. 5 is formed by rolling the same amphiphilic functional group activated carbon uniformly dispersed in a molten plastic as in Fig. 4 . The rate of seawater desalination of the permeable membrane in Fig. 5 is better than that of the permeable net in Fig. 4 .

Figure 6 shows the amphoteric functional rice husk carbon filled in a plastic container to form a fixed-bed FTA unit.

Figure 7 shows four fixed-bed FTA units connected in series to form a high-throughput TDS remover.

Wherein, the reference signs are explained as follows:

10: Method flow 101～110: Steps

20: Manufacturing and assembly process 220～280: Steps

30: spiral roll 310: through the net

330: Central water inlet pipe 600: FTA unit

640: container 610, 710: entrance

630, 730: exit 660: support grid

680: liquid distribution grid 700: module

Detailed ways

The invention provides an economical adsorbent to effectively and quickly remove ions from seawater stock solution in a nearly zero-power consumption manner, and becomes an innovative seawater desalination adsorption technology. For nearly two decades, the inventor of the present invention has devoted himself to the development of capacitive deionization CDI technology as a "chemical-free and low-energy consumption" seawater desalination technology. The results are found in US Patent Nos. 6,462,935 and 6,795,298, and Patents granted by other countries. CDI relies on the electrostatic field established by its desalination center, the flow-through capacitor FTC, to remove ions from seawater. CDI is only applied to the activated carbon electrode of FTC with a DC voltage of 1-3 volts, and at least 1/3 of the applied electric energy can be directly recovered and stored for backup when the FTC electrode is regenerated, so that the energy consumption of CDI is lower than that of RO desalination Law. However, the irreversibility of ion adsorption in the micropores of the activated carbon surface, and the inevitable water electrolysis generated by the operating voltage of 1-3 volts, make CDI technology unable to become a commercial seawater desalination method. The aforementioned irreversible ion adsorption and water electrolysis cause the FTC electrode to not be completely regenerated, the FTC electrode loses the adsorption center, leakage and TDS increase. Therefore, CDI is only suitable for desalination of seawater and brine with TDS below 5,000ppm. If CDI is used to desalinate wastewater with a TDS higher than 5,000ppm, the FTC electrodes will quickly saturate and cannot be regenerated, making CDI a useless technique. Practically, CDI needs a TDS load reducer to improve its low production capacity and difficulty in regeneration. The FTA provided by the invention will be able to meet the requirements of CDI.

Many water purification treatments are achieved through the adsorption of specific functional groups of various adsorbents and pollutants in water. The aforementioned specific functional groups can be designed and established on the surfaces of cellulose, polymer resins, crops, soil, biomass materials, ceramics, metal oxides, and activated carbon. Charged pollutants that can be removed by adsorption include: single or hydrated ions, heavy metals, organics, inorganics, blood and proteins. Generally speaking, the removal of ionic pollutants in water by adsorption requires neither power consumption nor complicated and expensive equipment. At the same time, if the combination between ions and the adsorbent is a kind of physical attraction, the adsorbed ions will be easily detached so that the adsorbent can be quickly regenerated. Table 1 lists some adsorbent-adsorbate pairings illustrating the correlation of specific functional groups with the adsorption of pollutants in water. Table 1 focuses on specific adsorption functional groups, therefore the adsorbents on which these functional groups are hosted are not listed in Table 1 for the sake of clarity.

Table 1: Adsorbent-adsorbate pairings

Among the ion-adsorbing functional groups listed in Table 1, and the ion-adsorbing atomic groups appearing in the literature, none of them have ever been disclosed as "capable of large-scale seawater desalination". The reason why the "adsorption seawater desalination method" has been neglected may be that seawater is a complex waste water. An average of 35g of salt is dissolved in 1 liter of seawater, or the TDS is 35,000ppm. In addition, there are organic pollutants that are difficult to remove in seawater. Dilute process. In typical seawater, the top five cations with the highest concentration, from high to low, are: Na ⁺ , Mg ²⁺ , Ca ²⁺ , K ⁺ and Sr ²⁺ ; similarly, the top five anions with the highest concentration, the concentration From high to low: Cl ^- , SO ₄ ^2- , HCO ₃ ^- , Br ^- and H ₂ BO ₃ ^- . In order to simultaneously remove cations and anions in seawater by "adsorption method", the adsorbent used must have sufficient surface area and an adsorption center of amphoteric functional groups. A range of materials including: activated carbon, carbon nanotubes, metal oxides (e.g. magnesium oxide, aluminum oxide, iron oxide, manganese oxide, zinc oxide, nickel oxide, copper oxide, tin oxide), metal carbides (e.g. Magnesium and barium carbide), cellulose, cotton, fluff, soil, silicate, ceramics and biomass materials, etc., can all be developed as adsorbents for the "adsorption desalination method". The present invention is based on the following characteristics of activated carbon. First, activated carbon is selected as the raw material of the amphoteric functional group adsorbent, and then made into a flow-through adsorber FTA unit. The characteristics of activated carbon are as follows:

1. Activated carbon has a wide range of raw materials;

2. Activated carbon has a huge surface area;

3. Activated carbon can resist the corrosion of seawater and its pollutants;

4. Activated carbon is easy to process;

5. Activated carbon is an environmentally friendly material; and

6. Compared with the raw materials of carbon nanotubes and some inorganic adsorbents, the price of activated carbon is low.

According to Table 1, the present invention selects phosphoric acid group (PO ₄ ^3- ) as the atomic group of cations adsorbing seawater, and ammonium group/amino acid (NH ₄ ⁺ /NH ₂ ) as the atomic group of anions adsorbing seawater. The present invention selects a kind of cheap active carbon commodity again, as the carrier of adsorption functional group. In other words, after the selected activated carbon undergoes phosphorylation and ammonization, the surface will obtain phosphate groups and ammonium groups, becoming an amphoteric functional activated carbon. The selected commercial activated carbon comes from coconut shell, has a specific surface area of 1,000m ² /g, and is usually used by water companies to filter drinking water and by semiconductor companies to adsorb volatile organic compounds. However, without the phosphorylation and ammonization mentioned in the present invention, the activated carbon or more expensive activated carbon cannot reduce the TDS of seawater at all.

Fig. 1 shows a kind of preferred specific embodiment of the present invention, and it is the preparation method that the active carbon that selects is converted through functional group, becomes the amphoteric functional group active carbon. In the process flow 10 of FIG. 1 , the required amount of selected activated carbon is put into a reaction vessel in step 101, and the material of the vessel can be ceramic, glass or stainless steel. Then, in step 102, according to the weight of the activated carbon, a phosphorylation agent is added into the reaction vessel at a specific ratio for phosphorylation. In the phosphorylation of activated carbon, phosphoric acid (H ₃ PO ₄ ) is the main agent, accounting for the largest proportion, and diammonium hydrogen phosphate [(NH ₄ ) ₂ HPO ₄ ] and urea can be used as auxiliary agents. Phosphorylation is to mix activated carbon with the aqueous solution of the above-mentioned medicines, and carry out 1 to 3 hours in the air at 140°C to 200°C. After phosphorylation, the generated activated carbon mud water is filtered in step 103, and the phosphorylated residual agent is removed with clear water. Phosphorylated residual reagents must be completely removed to prevent them from interfering with subsequent ammonification. The pH and TDS of the phosphorylated activated carbon cleaning solution can be used as the basis for judging the cleanliness of activated carbon, that is, the pH is between 6 and 8, and the TDS should be below 300ppm. There are many choices of reagents for the ammonization reaction of activated carbon, including: ammonia gas (NH ₃ ), ammonia water (NH ₄ OH), tertiary and quaternary amines, linear and aromatic amines, heterocyclic amines, and ammonium salts (including Chlorine, bromine, nitric acid, perchloric acid and other salts). The present invention selects the same from the aforementioned medicaments, and in step 104, the ammonization reaction of activated carbon after phosphorylation is carried out at a temperature range of 45°C to 100°C and a time of 6 to 12 hours. After the ammonification reaction, the activated carbon mud chemically treated twice is filtered and washed in step 105, and then subjected to vacuum heating and drying for more than ten hours in step 106. Finally in step 110, the dried activated carbon with amphoteric functional groups is stored for future use.

As a filter material for water treatment, activated carbon is generally used as a fixed bed in a packed filter. Due to the small particle size, the activated carbon powder forms dense clods with water, allowing water to permeate through rather than rapidly flow through the FTA containing activated carbon powder clods. Therefore, the present invention fixes the active carbon powder of the amphoteric functional group on a net-like substrate, so that water can quickly flow through the FTA containing the active carbon net. Considering water resistance and cost, polymer material is the best substrate to support activated carbon powder with amphoteric functional groups. Suitable polymeric substrates include: cellulose acetate, cellulose triacetate, polyamide, polypropylene, polysulfone, polycarbonate, polyvinyl chloride, polyester and polytetrafluoroethylene. At the same time, the polymer substrate must have a network structure so that water can flow freely and quickly after it is coated with amphoteric functional group activated carbon powder. Figure 2 shows a preferred embodiment of the present invention for immobilizing activated carbon powder, including the fabrication of the coating net, and the installation of the coating net as an FTA unit for TDS removal in a container. In the production and assembly process 20 of Fig. 2, a piece of plastic mesh is prepared in step 220 with the required size, and in step 240, the activated carbon powder with amphoteric functional group is sprayed and solidified and positioned on the mesh to become a piece of coated plastic mesh. cloth net. The coating net is then folded into the shape of an accordion in step 260, and then, in step 280, several required accordion coating nets are stuffed into a plastic pipe with water flow at both ends to form an independent FTA unit . As shown in Figure 2: the flow of water in the FTA unit is perpendicular to the surface of the coated mesh, making the maximum utilization of the adsorbent. The coated mesh relies on the adhesive to locate the amphoteric functional group activated carbon powder on the mesh, so the lifetime of the adsorbent passing through the mesh depends on the binding force of the adhesive. Therefore, when the coating network is folded, or the water flow continuously exerts pressure on the coating layer, the loss of the amphoteric functional group activated carbon powder is unavoidable.

In order to reduce the loss of activated carbon powder, and in order to reduce the interference of the adhesive covering the activated carbon powder, the present invention evaluates two specific implementation techniques of "melting the amphoteric functional group activated carbon powder and the plastic substrate into one". In one of the technologies, a specific amount of activated carbon powder is evenly dispersed in a molten plastic, and then rolled into a porous adsorbent permeable membrane in a non-woven manner. Another technique is to use a blanket made of activated carbon powder without chemical treatment, and convert it into an amphoteric functional group adsorbent permeable blanket by the method shown in Figure 1. No matter what kind of carbon powder is used in the activated carbon blanket, the method in Figure 1 can make it into an amphoteric functional group activated carbon. Both the adsorbent permeable membrane and the adsorbent permeable blanket can be made into independent FTA units through the assembly method shown in FIG. 2 . In appearance, the adsorbent permeable membrane and the adsorbent permeable blanket are similar to scraping sponges for kitchen utensils, such as 3M Baili; In addition to the adjustable amount of carbon powder used in the adsorbent permeation membrane and the adsorbent permeation blanket, the pore size of the flow channel in their three-dimensional structure can also be customized to meet the needs of the application. Similar carbon powder filled items can also be found in N-95 masks, air filters, bamboo charcoal cloth, and US Patent No. 6,117,328.

Using FTA's "adsorption desalination" technology, its production capacity depends on the area of the adsorbent permeation net, adsorbent permeation membrane, or adsorbent permeation blanket in the FTA. The same logic also appears in ultrafiltration and RO filter elements, that is, the production capacity is proportional to the area of the filter material. All over the world, filter elements are made in the shape of spiral coils. The reason is: the spiral coil can provide the largest area with the smallest volume. Fig. 3 shows a specific embodiment of a preferred FTA adsorption spiral coil of the present invention. The spiral coil 30 shown in FIG. 3 is formed by concentric winding along a central water inlet pipe 330 with a permeable net, permeable film, or permeable blanket 310 . At the same time, the upper and lower sides of the spiral wrap are sealed to prevent water leakage. As shown in Fig. 3: some holes are drilled on the central water inlet pipe 330 to allow water to flow into the spiral coil, and the arrows shown in Fig. 3 shoot out layers of adsorbent vertically. When the influent water flows through the spiral coil, the ions in the water come into contact with the adsorbent and are attracted. When the adsorbent of the spiral coil is saturated, the adsorbent can be regenerated by flowing an appropriate amount of cleaning water through the spiral coil. The adsorbent spiral core in Figure 3 can be produced with the same process and specifications as ultrafiltration and RO filter elements, so that the current hardware for ultrafiltration and RO can be used for FTA products. FTA borrows the ultrafiltration and RO product systems that have been marketed for many years and has dominated the water treatment market. People can use innovative FTA products with their familiar habits and knowledge, which will help the promotion of FTA products in the water treatment market. FTA products can also contribute a new method with no pollution and low energy consumption in the application of TDS removal in the water treatment market.

The production of activated carbon is a highly polluting and energy-intensive industry. The processing of activated carbon first carbonizes the raw material of activated carbon at 400°C, and then activates it at 800°C to produce a large surface area. The whole process consumes a lot of energy and produces a lot of air pollution of carbon dioxide, smog and ash. However, the raw material of activated carbon can be carbonized into various amphoteric functional group adsorbents at a lower temperature and in a shorter time. Although the substance produced by low-temperature processing is charcoal rather than activated carbon, the amphoteric functional group charcoal adsorbent is more suitable than activated carbon for "adsorption desalination" to produce fresh water. Since the low-temperature carbonization is carried out under the cover of chemicals and without flame, no carbon dioxide and smoke are produced (only water vapor is produced). Many agricultural wastes and biomass materials are produced around the world and can be used as raw materials for adsorbents for TDS removal. Some of the raw materials for adsorbents are listed below:

1) Husks or stalks of the following grains: rice, wheat, barley, oats, rye, sorghum, corn, soybeans and soybeans.

2) The shell or fruit of the following fruits: coconut, palm, durian, mango and peach.

3) The peel or pomace of the following fruits: pineapple, citrus, grapefruit, jackfruit and sugar cane.

4) Shells of the following nuts: peanuts, walnuts, ginkgo nuts (mincenuts), cashews, almonds, acorns and agarose.

5) Cellulose and lignin in the following substances: flax, wood chips, sawdust, bamboo and fibers (cotton/cotton/yarn/silk/velvet).

After evaluating the above-mentioned raw materials, the present invention selects rice husk as the raw material of the adsorbent for removing TDS, and evaluates the performance of rice husk charcoal in reducing TDS of seawater, wastewater and tap water. The local rice husks purchased in Taiwan, China in the present invention are not reprocessed, and are directly phosphorylated and ammonized with the process shown in FIG. 1 . The hardness of rice husk comes from two hard components: silica (SiO ₂ ) and lignin [C ₉ H ₁₀ O ₃ ·(OCH ₃ ) _0.9-1,7 ] _n . Among the typical components of rice husk, cellulose [(C ₆ H ₁₀ O ₅ ) _x ] is the most, accounting for about 44% to 60%, which contains lignin and hemicellulose [(C ₅ H ₈ O ₄ ) _m ]. The remaining ingredients of rice husk are: silica-based inorganic ash, and volatile substances such as water/fat/protein. Lignin is a mononuclear aromatic polymer that acts as a bonding agent for cellulose, and is also combined with hemicellulose to act as a guide for water flow in plants. The main purpose of the phosphorylation of the rice husk in the present invention is to carbonize the lignin of the rice husk, and at the same time multiply the functional group for adsorbing cations on the carbon chain. To achieve carbonization of rice husk, phosphorylation is carried out at 200 to 400°C. The degree of blackening of rice husk is a sign of whether the phosphorylation is complete or not, and depends on three reaction parameters: the weight ratio of rice husk to phosphorylation agent, reaction temperature and reaction time. Experiments have shown that the more complete the carbonization of rice husk, the higher the ion adsorption rate. However, excessive carbonization will crush the rice husk charcoal into fine particles, resulting in a large amount of material loss. The ammonization of rice husk charcoal uses the same reaction conditions as activated carbon, and finally makes an amphoteric functional group rice husk charcoal adsorbent.

Different from the multiple installation methods of amphoteric functional group activated carbon in the FTA unit, the best installation of amphoteric functional group rice husk carbon in the FTA unit is in the form of a packed bed. Fig. 6 shows the concrete implementation that a kind of preferred amphoteric functional group rice husk charcoal of the present invention is installed in the FTA unit: in the FTA unit 600, the particle of amphoteric functional rice husk charcoal is between two support grids 660, fills up container 640 The interior space becomes the fixed bed FTA. According to the inner diameter and height ratio of the container 640, or the aspect ratio (aspect ratio), one or more liquid distribution grids 680 must be placed in the middle of the packed bed of rice husk charcoal, so that the water can be evenly distributed in the fixed bed FTA cassette Flow through and fully contact with rice husk charcoal. Wastewater enters the fixed bed FTA unit 600 from the inlet 610 , and then flows out from the outlet 630 of the FTA unit 600 by gravity or pumping. In order to improve the treatment result of wastewater flowing through once, multiple fixed-bed FTA units can be used in series, such as the module 700 shown in Figure 7, in which 4 FTA units equipped with amphoteric functional group rice husk carbon packed beds are connected in series. The waste water flows in from the inlet 710 and flows out from the outlet 730, and is treated in cascade flow. At least two flow-through adsorber units can also be combined in parallel. Through the phosphorylation and ammonification of the present invention, the above-mentioned agricultural wastes and biomass materials can be converted into adsorbents for removing TDS like rice husks.

No matter the adsorbent permeates the net, the adsorbent permeates the membrane, the adsorbent permeates the blanket or the adsorbent packed bed, the FTA using the adsorbent of the present invention can rapidly increase the TDS in the water when the wastewater contacts the adsorbent. significantly reduced. Furthermore, the phosphorylation and ammonization disclosed in the present invention can transform powdery and granular activated carbon, agricultural waste and biomass materials into powerful and effective adsorbents. The mechanism by which the sorbent removes ions is not ion exchange, because the TDS of the wash water used to regenerate the sorbent is lower than the TDS of the wastewater being treated (ie, the former contains fewer ions). In many FTA applications, the wash water contains only a very small amount of ions, for example, distilled water and deionized water produced by RO. The aforementioned low TDS cleaning water can make the surface of the adsorbent very clean. Therefore, the "adsorption of desalination" mechanism of the present invention should be a physical attraction between the active center of the adsorbent and the absorbed ions, and the attraction is restricted by the ionic strength of water. Simply put, the ionic strength is the sum of the concentration of each ion in water multiplied by the square of the valence of the ion. When the water with low ionic strength contacts the saturated adsorbent, the adsorbed ions of the high ionic strength water will be driven away, regenerate the active center on the surface of the adsorbent, and continue to perform the function of removing TDS. The present invention also includes: a first electronic controller for managing the removal of total dissolved solids; and a second electronic controller for managing the regeneration of the flow-through adsorber unit, wherein the first electronic controller Including online detectors for detecting the conductivity, pH and total dissolved solids of the liquid, the second electronic controller includes online detectors for detecting the conductivity, pH and total dissolved solids of the liquid. The following four examples demonstrate the ability and yield of the FTA disclosed in the present invention to remove TDS from various water samples with different adsorbents. However, these examples are not intended to limit the scope of application of the present invention.

Example 1

Without any treatment, a batch of seawater raw liquid taken from the Taiwan Strait of China was directly desalted with an adsorbent containing activated carbon with amphoteric functional groups through the net. The adsorbent is formed by coating a slurry of activated carbon powder on a polypropylene mesh with a width of 100 mm, a length of 1,000 mm, a thickness of 0.6 mm, and a mesh hole of 1 mm ² through the mesh. The dose of activated carbon in each adsorbent net is 60g/1m ² , and the six adsorbent permeable nets contain a total of 36g of activated carbon. The plastic tube becomes the flow-through adsorber FTA. Then, 5 liters of the above seawater was sent into the FTA pipe, flowed through the adsorbent permeation net to the collection tank for TDS measurement. After each time 5 liters of seawater flowed through the FTA pipe, the six adsorbent networks in the FTA pipe were regenerated with 2 liters of tap water. One ion adsorption plus one ion desorption (i.e. adsorbent regeneration) constitutes a seawater desalination cycle. A seawater desalination cycle takes about 1 minute, and the six adsorbent nets can perform the next seawater desalination cycle.

Figure 4 shows the relationship between the TDS decrease of seawater and the number of desalination cycles. The initial TDS of seawater is 26.8ppt (26.8 per thousand), and the TDS value of seawater is measured every 5 consecutive desalination cycles. From the data in Figure 4, the following three inferences can be drawn:

1. Only one desalination cycle can reduce the TDS of 5 liters of seawater by 300-500 ppm (300 to 500 parts per million); however, every 5 consecutive desalination cycles can reduce the TDS by 2200-2600 ppm.

2. Using tap water as cleaning water can completely regenerate the adsorbent network.

3. When the ion content of seawater decreases, the desalination rate of each desalination cycle decreases accordingly.

In Example 1, the adsorbent is not yet saturated, that is, it is regenerated. Monitoring the TDS of the effluent water can tell whether the adsorbent is saturated. When the TDS of the effluent water shows an upward trend, it means that the adsorbent has reached saturation. Therefore, an online conductivity/TDS monitor can determine the correct time for sorbent regeneration. The adsorption yield of amphoteric activated carbons can be expressed in milliequivalents per gram (mEq/g), or as the weight ratio of the adsorbed salt, such as sodium chloride (NaCl), to the activated carbon adsorbent. Different from the surface of ion exchange resin, which can only have a fixed number of monosexual (cation or anion) functional groups, the surface of activated carbon can be colonized with amphoteric functional groups, and can be made into the form of permeable mesh, permeable membrane, permeable blanket or packed bed . When the activated carbon blanket is phosphorylated and ammonized, not only the activated carbon, but also the plastic carrier may also endow the amphoteric functional group.

Example 2

Using the same amphoteric functional activated carbon as in Example 1 as a filler, add it to molten polypropylene and mix evenly to prepare an adsorbent permeable membrane with an activated carbon concentration of 240 g/m ² . Take a section of 150mm wide, 470mm long, 3mm thick adsorbent permeable membrane containing about 17g of activated carbon, fold it into the shape of an accordion, and carry out the desalination cycle similar to Example 1 of 1 liter of seawater stock solution. Figure 5 shows the correlation between the decrease of TDS of seawater and the number of desalination cycles, in which the TDS of seawater dropped from 23,900ppm to 306ppm, which is close to the TDS level of drinking water. For seawater desalination in Example 2, only activated carbon adsorbent was used to permeate the membrane without any other treatment.

Under the use of the same amount of activated carbon, the desalination rate of each desalination cycle of the adsorbent permeating the membrane in Figure 5 is 4 times that of the adsorbent permeating the net in Figure 4. The biggest difference between the adsorbent permeable membrane and the adsorbent permeable net is that the former has a three-dimensional structure while the latter has a two-dimensional structure, so the former has a higher utilization efficiency of the adsorbent. Figure 5 still shows that as the salinity of seawater decreases, the removal of TDS follows a downward trend. However, the desalination rate of each desalination cycle is still maintained at 25%. In other words, regardless of the salinity of the seawater, the adsorbent can remove 25% of the salt content of the incoming seawater through the membrane. Compared with the adsorbent permeating the membrane, the activated carbon content of the adsorbent permeating the blanket is higher, so the desalination capacity of the permeating blanket is higher than that of the permeating membrane.

Example 3

Except that the activated carbon content is 60g/m ² , the activated carbon adsorbent permeated membrane of Example 2 was used in a seawater desalination test in Bohai Bay, mainland China. The test uses 6 plastic tubes with a diameter of 6" (150mm inner diameter) and a length of 40" (1 meter) in series, and each tube is plugged with a ^7.5m2 accordion-shaped adsorbent permeable membrane. The total permeable membrane area is 45m ² . A batch of local seawater stock solution with a TDS of 24,000ppm was treated to remove TDS with the aforementioned series-connected FTA module. Table 2 lists a typical set of data in the test, collecting one barrel of effluent water per minute, with a flow rate of 600 liters per hour, and the volume of each barrel is 10 liters. After the TDS value of each barrel of water is measured, it is listed in the second column of the table. In the field test in Table 2, only the pump for transporting seawater uses electricity, and the process of removing TDS by the adsorbent uses no electricity.

Table 2: Field test of "adsorption desalination" of seawater stock solution in Bohai Bay with a TDS of 24,800ppm by FTA using activated carbon adsorbent to permeate the membrane [water flow rate: 0.6m ³ /hour (600 liters per hour)]

water output per minute TDS of effluent (ppm,mg/L) 0 240 1 410 2 550 3 990 4 1,500 5 2,400 6 4,320 7 8,700 8 10,450 9 Sorbent permeation membrane for regenerated FTA

Table 2 clearly shows the "commercial" feasibility of "adsorption seawater desalination" technology. The launch of "FTA seawater desalination system" must first complete the following subsystem hardware and control logic:

1. Detect the TDS of the effluent water online to determine the regeneration time of the FTA unit.

2. Automatic switching between adsorption and regeneration of FTA unit.

3. The execution specification of FTA unit regeneration: waste water discharge/clean water consumption and recovery/regeneration sequence.

4. Monitoring and maintenance of the functional stability of the FTA unit.

5. Recovery of economically valuable resources in seawater.

6. Post-treatment of adsorbed pollutants.

The present invention has proved that: the use of activated carbon with amphoteric functional groups as the adsorbent of the "adsorption seawater desalination" technology can avoid the "dosing→precipitation→flotation→filtration" of general seawater desalination technology such as distillation, RO, electrodialysis and ion exchange It can directly desalinize the raw seawater solution without electricity, simplify the seawater desalination process, and eliminate the cost and pollution of chemical dosing. The strength, fast ion absorption and fast regeneration of the amphoteric functional group activated carbon adsorbent were also verified.

Example 4

Through the functional group conversion method shown in Figure 1, a rice husk produced locally in Taiwan is first carbonized, and then ammonized to become amphifunctional rice husk charcoal, which is used as an adsorbent for the "adsorption seawater desalination" technology. In the series connection method shown in Figure 7, six fixed-bed FTA units containing rice husk charcoal are connected to form a group of stepped TDS removers. Each FTA unit is equipped with 80g rice husk charcoal, 6 tubes with a total of 480g adsorbent for TDS removal test. The internal volume of each FTA unit is 500cc. After filling 80g of rice husk charcoal, there is no free space, but the rice husk charcoal can hold 250 to 350cc of water. Table 3 summarizes the four water samples treated with the above-mentioned 6-connected rice husk charcoal fixed-bed FTA unit. In the process of reducing TDS, the TDS of ion absorption and FTA regeneration changes, that is, ΔTDS (ΔTDS = TDS after treatment – treatment ex-TDS):

Table 3 The test of four kinds of water samples to reduce TDS by fixed bed FTA of 6 rice husk charcoal in series

Table 3 shows that the ΔTDS values of the effluent water and the residual water (adsorbed by rice husk charcoal) in the FTA unit are very different, and the TDS decline rate of the former is much higher than that of the latter. This is because the effluent water passes through six FTA units to absorb ions step by step, and the TDS drops greatly, while the residual water in the FTA unit is located after the effluent water. Due to the gradual saturation of the adsorbent, the available adsorption centers are reduced, so the residual water The TDS is at a high level. From this point of view, the wastewater flows through one FTA unit once, and the maximum TDS removal capacity of FTA depends on the following three factors:

1. The volume through which the waste water flows.

2. The amount (weight) of adsorbent.

3. The capacity and capacity of the adsorbent.

The rice husk charcoal with amphoteric functional groups disclosed by the present invention is not activated, that is, the rice husk charcoal is not subjected to a catalytic reaction at 800-900°C and an oxygen-free state to form a porous surface structure. Therefore, the surface area of the amphoteric functional group rice husk charcoal of the present invention is far less than that of commercial activated carbon. However, the ability of amphoteric functional rice husk carbon to desalinate seawater is greater than that of amphoteric functional activated carbon. Rice husk charcoal can soften tap water (see Test 1 in Table 3), and modified activated carbon cannot soften tap water substantially. Furthermore, the regeneration efficiency of rice husk charcoal is better than modified activated carbon. The surface of activated carbon has nanoscale pores, and the surface of rice husk charcoal is smoother, which proves that the surface micropores of the adsorbent are not required for the "adsorption desalination" technology. In terms of the yield of functional group conversion reaction, activated carbon is superior to rice husk carbon, because the yield of activated carbon is close to 100%. Since rice husk contains volatile components, tar, ashes and particles, rice husk will lose 20-30% of its weight during low-temperature carbonization, and the yield rate is only 70-80%. Among agricultural wastes and biomass materials, bagasse and bamboo contain higher lignin than rice husk and lower ash content, so bagasse and bamboo should be more suitable than rice husk as raw materials for the production of adsorbent carbon. However, considering the global rice cultivation area, rice husk has the advantages of stable source and easy processing.

"Sorption" has been used in seawater desalination for more than 40 years. Unfortunately, the focus of development is on the processor of capacitive deionization CDI, that is, the flow-through capacitor FTC. Activated carbon and aerosol carbon are common materials for the early development of FTC electrodes. In recent years, some people have studied carbon nanotubes, graphene, and metal oxides as materials for FTC electrodes. Carbon nanotubes, graphene or similar carbon materials, in addition to being expensive, their nanopores prevent electrode regeneration. When ions enter the nanopores, it is difficult to expel them, causing the FTC electrode to lose its adsorption area. The activated carbon used in the present invention originally has no ability to remove TDS, but after the phosphorylation and ammonization disclosed in the present invention, it becomes an amphoteric functional group activated carbon, which can shine in the "adsorption of seawater desalination". The invention also proves that the rice husk of the agricultural waste can be made into a more effective adsorbent than the bifunctional functional group activated carbon, and has a wider range of water treatment applications. Among agricultural wastes and biomass materials, there are other raw materials with more potential than rice husks waiting to be developed as adsorbents for TDS removal or other applications. Since the adsorbent must first make its surface free of any ions, it can quickly and massively reduce the TDS of wastewater to a low level, such as below 20ppm. To make the adsorbent reach 20ppm, you must use lower TDS cleaning water, such as deionized water with a TDS of 1ppm. Cleaning the adsorbent with deionized water is an uneconomical process. In the category of low TDS, such as below 100ppm, CDI relies on the electric field to adsorb and desorb ions. When the electric field is turned off, the ions are automatically desorbed from the surface of the FTC electrode, and the amount of cleaning water used for FTC electrodes is lower than that of amphoteric functional groups. There is less cleaning of agents in the low TDS range. Therefore, the amphoteric functional group adsorbent can complement CDI and serve as a TDS load-sharing tool for CDI, and hand over the ultra-low TDS water treatment work to CDI. Amphoteric functional group adsorbents can also assist water treatment systems such as "distillation, RO, electrodialysis, and ion exchange" to solve the cost and pollution problems of chemical pretreatment.

Through the above detailed description of the preferred embodiments, it is hoped that the characteristics and spirit of the present invention can be described more clearly, and the scope of the present invention is not limited by the preferred embodiments disclosed above. On the contrary, the intention is to cover various modifications and equivalent arrangements within the scope of the appended claims of the present invention. Therefore, the scope of the claims applied for in the present invention should be interpreted in the broadest way based on the above description, so as to cover all possible changes and equivalent arrangements.

Claims (15)

1. flow through a formula absorber in order to what remove total dissolved solid, comprise:

At least onely flow through formula adsorber unit, comprise:

One container; And

A pair of functional group adsorbent, at least one method is placed in this container, and this Shuan Xing functional group adsorbent surface possesses the atomic group of the Liquidity limit coming from phosphorylation reaction and comes from the atomic group of the adsorpting anion that ammoniumization is reacted;

At least one entrance, is arranged at and this container enters this for a liquid flows through formula adsorber unit;

At least one outlet, is arranged at and this container leaves this for this liquid flows through formula adsorber unit;

At least one pump, flows through formula adsorber unit to carry out the removal of total dissolved solid in order to promote this liquid through this;

At least one cleaning fluid, flows through formula adsorber unit in order to regenerate this;

One first electronic controller, in order to manage the removal of total dissolved solid; And

One second electronic controller, in order to manage the regeneration that this flows through formula adsorber unit.

2. as claimed in claim 1 flow through formula absorber in order to what remove total dissolved solid, wherein the raw material of this Shuan Xing functional group adsorbent is selected from one group of material, comprising: activated carbon, CNT, magnesia, aluminium oxide, iron oxide, manganese oxide, zinc oxide, nickel oxide, cupric oxide, tin oxide, magnesium carbide, barium carbide, earth, silicate and pottery.

3. as claimed in claim 1 flow through formula absorber in order to what remove total dissolved solid, wherein the raw material of this Shuan Xing functional group adsorbent is selected from shell or the stalk of cereal, and described cereal comprises: rice, wheat, barley, oat, rye, Chinese sorghum, corn, soybean and soya bean.

4. as claimed in claim 1 flow through formula absorber in order to what remove total dissolved solid, wherein the raw material of this Shuan Xing functional group adsorbent be selected from the shell of fruit or son real, described fruit comprises: coconut, palm, durian, mango and honey peach.

5. as claimed in claim 1 flow through formula absorber in order to what remove total dissolved solid, wherein the raw material of this Shuan Xing functional group adsorbent is selected from pericarp or the slag of fruit, and described fruit comprises: pineapple, oranges and tangerines, shaddock, jackfruit and sugarcane.

6. as claimed in claim 1 flow through formula absorber in order to what remove total dissolved solid, wherein the raw material of this Shuan Xing functional group adsorbent is selected from the shell of nut, and described nut comprises: peanut, English walnut, ginkgo nut, cashew nut, almond, acorn nut and acorn-cup fruit.

7. as claimed in claim 1 flow through formula absorber in order to what remove total dissolved solid, wherein the raw material of this Shuan Xing functional group adsorbent is selected from cellulose from a material and lignin, and this material comprises: flax, wood fragments, sawdust, bamboo and fiber; Described fiber comprises cotton, silk floss, yarn, silk and suede further.

8. as claimed in claim 1 flow through formula absorber in order to what remove total dissolved solid, wherein phosphoric acid is the major pharmaceutical agent of phosphorylation reaction.

9. as claimed in claim 1 flow through formula absorber in order to what remove total dissolved solid, the medicament of wherein ammoniumization reaction is selected from one group of chemicals, comprising: ammonia, ammoniacal liquor, three grades and quaternary ammonium compound, straight chain and aromatic amine, heterocyclic amine, and ammonium salt; Described ammonium salt comprises ammonium chloride, ammonium bromide, ammonium nitrate and ammonium perchlorate further.

10. as claimed in claim 1 flow through formula absorber in order to what remove total dissolved solid, wherein this Shuan Xing functional group adsorbent is in the container flowing through formula adsorber unit, with through net, through film, install through the mode of blanket or packed bed.

11. as claimed in claim 1 flow through formula absorber in order to what remove total dissolved solid, and wherein this cleaning fluid is selected from one group of material, comprising: the seawater of running water, distilled water, deionized water, the surface water, underground water and low total dissolved solid.

12. as claimed in claim 1 flow through formula absorber in order to what remove total dissolved solid, wherein the first electronic controller of the removal of this management total dissolved solid, comprises the online detector of the electrical conductivity for detecting liquid, acid-base value and total dissolved solid.

13. as claimed in claim 1 flow through formula absorber in order to what remove total dissolved solid, wherein the second electronic controller of the regeneration of formula adsorber unit is flow through in this management, comprises the online detector of the electrical conductivity for detecting liquid, acid-base value and total dissolved solid.

14. as claimed in claim 1 flow through formula absorber in order to what remove total dissolved solid, comprise at least two further and flow through the parallel combination that formula adsorber unit formed.

15. as claimed in claim 1 flow through formula absorber in order to what remove total dissolved solid, comprise at least two further and flow through the tandem compound that formula adsorber unit formed.