JP4674854B2 - Wastewater treatment method - Google Patents

Description

  The present invention relates to a wastewater treatment method. More specifically, the present invention relates to a method for treating waste water containing at least one of boron and fluorine.

There is a growing interest in the effects of trace elements in the environment on human health and ecosystems. Against this background, in February 1999, water quality standards, boron = 1.0 mg · dm ⁻³ (= ppm), fluorine = 0.80 mg · dm ⁻³ were shown. The wastewater standard values of boron = 10 mg · dm ⁻³ , fluorine = 8 mg · dm ⁻³ and boron = 230 mg · dm ⁻³ and fluorine = 15 mg · dm ⁻³ were enforced in the sea area.

  Boron compounds such as boric acid, borax, and borate and fluorine compounds such as hydrofluoric acid, sodium fluoride, and calcium fluoride are industrially useful substances and are widely used in industrial products. Boron and fluorine containing wastewater is produced in the manufacturing process. In addition, since some industrial products contain boron compounds and fluorine compounds, there are cases where boron and fluorine are contained in the waste incineration sewage effluent and waste incineration ash landfill disposal water. The drainage may contain fluorine in addition to boron. For example, flue gas desulfurization apparatus waste water from a coal-fired power plant contains fluorine in addition to boron. Accordingly, in order to efficiently treat boron and fluorine trace elements in wastewater, development of a wastewater treatment method having excellent adsorption performance for these boron and fluorine is required.

  By the way, as a treatment method of boron-containing wastewater, conventionally, a coagulation precipitation treatment in which a coagulant is added and boron is removed as an insoluble precipitate, an adsorption removal method in which boron is adsorbed on an adsorbent, and solvent extraction extracted with an organic solvent. Various treatment methods such as treatment, reverse osmosis membrane treatment using a reverse osmosis membrane, evaporation treatment for evaporating and drying waste water, and combinations thereof have been proposed. Among these, the adsorption removal method is considered to be an excellent treatment method for boron-containing wastewater that does not generate sludge. This adsorption removal method is to adsorb boron in waste water to an adsorbent, and boron-selective ion exchange resin, activated carbon, activated alumina, and the like are known as adsorbents for boron treatment.

JP 08-238478 A JP 08-89956 A

  However, although inorganic adsorbents are excellent in heat resistance, oxidation resistance, etc., cost reduction can be expected, but the adsorption performance of activated carbon and activated alumina is significantly lower than that of ion exchange resins. . On the other hand, although ion exchange resins exhibit relatively higher boron adsorption performance than inorganic adsorbents such as activated alumina, there is a limit to the adsorption capacity. There's a problem. In addition, since it is a polymer material, there is a concern about performance degradation due to use at high temperatures or resin decomposition.

  An object of the present invention is to provide a wastewater treatment method excellent in performance for adsorbing and removing these substances to be adsorbed with respect to wastewater containing at least one of boron and fluorine.

As a result of intensive studies to solve the above problems, the present inventors have found that a porous body mainly composed of zirconium is excellent in the adsorption performance of boron and fluorine, and further, this porous body is hexagonal. In the case of the structure, it has been found that the adsorption performance is more excellent .

The present invention is based on such knowledge, and the waste water treatment method according to claim 1 is characterized in that at least one of boron and fluorine is an adsorbed substance, and the waste water containing the adsorbed substance is mainly composed of zirconium. The porous material is made by using a surfactant as a template, and the surfactant in the pores is removed with an alkali and treated with an acid. After that, it is in contact with drainage.

Here, the present invention is arbitrary preferred that the porous body has a hexagonal structure.

In the wastewater treatment method according to the third aspect of the present invention, the adsorption reaction is caused to occur in a pH region substantially equal to the inverse logarithm value pKa of the acid dissociation constant (Ka) of the substance to be adsorbed.

Further, in the wastewater treatment method according to the fourth aspect of the present invention, the porous body that has adsorbed the adsorbed substance is regenerated with an acid and reused.

Thus, according to the method of the present invention, the porous body mainly composed of zirconium exhibits higher adsorption performance for boron and fluorine than the ion exchange resin, and exhibits a large adsorption capacity. Adsorbed and boron and fluorine contained in the waste water can be removed well over a long period of time. Therefore, even when applied to high-concentration wastewater, if a removal device such as a large adsorption tower is not required or a large removal device is used, long-term stable removal is possible.

Further, since the adsorbent is composed of zirconium , the cost can be expected to be lower than that of an ion exchange resin, and there is no concern about performance degradation due to use at a high temperature like the ion exchange resin or decomposition of the resin. Moreover, since the porous body after use can be regenerated, it is economical.

In the wastewater treatment method of the present invention, wastewater containing an adsorbed substance is brought into contact with a porous body mainly composed of zirconium to adsorb and remove the adsorbed substance. Here, the adsorbed substance to be adsorbed in the wastewater is at least one of boron and fluorine, and the wastewater to be treated is a wastewater of any origin as long as it contains the adsorbed substance. Also good. That is, among boron and fluorine, wastewater containing only boron as an adsorbed substance, wastewater containing only fluorine as an adsorbed substance, or wastewater containing both boron and fluorine as an adsorbed substance may be used. In addition, wastewater includes, for example, exhaust gas desulfurization wastewater from thermal power plants such as coal-fired power plants, wastewater discharged from industries such as the semiconductor industry, wastewater from waste incineration plants, and at least boron and fluorine. As long as the water contains any one of them, tap water, groundwater, river lake water, and the like are included, but are not limited thereto.

  Moreover, what has a hexagonal structure as a porous body is preferable. Porous materials having a hexagonal structure (for example, porous zirconium: Zr-S) adsorb boron and fluorine compared to porous materials having no hexagonal structure (for example, a thermal decomposition product of zirconium oxynitrate: Zr-N). The amount is large (see FIG. 5).

The porous body is manufactured using a surfactant as a mold. For example, a zirconium source and a surfactant are mixed, heated to 100 ° C., and the precipitate is aged for 48 hours. The obtained precipitate is filtered and dried to obtain a porous body. Examples of the zirconium source include zirconium sulfate, sulfate (zirconium sulfate (IV) tetrahydrate Zr (SO ₄ ) ₂ · 4H ₂ O), fluoride salt (zirconium fluoride (III) ZrF ₃ , fluoride Zirconium (IV) ZrF ₄ ), chloride salt (zirconium chloride (III) ZrCl ₃ , zirconium chloride (IV) ZrCl ₄ ), nitrate (zirconium nitrate (IV) pentahydrate Zr (NO ₃ ) ₄ · 5H ₂ O ), Oxide (zirconium oxide ZrO ₂ ), oxychloride (zirconium dichloride (IV) octahydrate ZrCl ₂ O · 8H ₂ O), oxynitrate (zirconium dinitrate (IV) dihydrate dihydrate) Zr (NO ₃ ) ₂ O · 8H ₂ O), acetate salt (zirconium acetate Zr (CHCOO) ₄ ), and the like can be mentioned. Among them, use of zirconium sulfate is preferable. The surfactant preferably contains alkyltrimethylammonium [C _n H _{2n + 1} N ⁺ (CH ₃ ) ₃ ], and the anion for neutralizing the charge is Cl ⁻ , Br ⁻ , OH- ^{and the} like. The carbon number (n) of the alkyl chain is preferably 8 to 20, and more preferably hexadecyltrimethylammonium bromide ([CH ₃ (CH ₂ ) ₁₅ N (CH ₃ ) ₃ ] Br) in which n = 16 is used. preferable. The addition amount of the surfactant is preferably larger than the critical micelle concentration and smaller than the production concentration of the liquid crystal phase, and in the case of hexadecyltrimethylammonium bromide, preferably 0.03 to 26 wt%, and further 25 wt% It is more preferable to use%.

  Next, when producing a porous body using a surfactant as a template, the present inventors have found that the adsorption performance is exhibited even if the surfactant is left in the pores as it is.

  Of course, it may be used after removing the surfactant. If the surfactant in the pores is removed while maintaining the pore structure and adsorption capacity of the porous body, the adsorption performance of the porous body is improved.

  Specifically, the surfactant in the porous body may be removed with an alkali and then treated with an acid.

  Here, the alkali is to adjust the pH of the water to be treated to the alkaline region, and examples thereof include sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, calcium hydroxide, and preferably sodium hydroxide. There are, but are not limited to these.

Examples of the acid include sulfuric acid (H ₂ SO ₄ ), hydrochloric acid (HCI), nitric acid (HNO ₃ ), phosphoric acid (H ₃ PO ₄ ), and acetic acid (CH ₃ COOH), preferably sulfuric acid (H ₂ SO ₄ ), but is not limited to these.

Here, the case of Zr-S will be specifically described below as an example. When Zr-S is brought into contact with an alkaline solution, the reaction proceeds in the direction of lowering the pH of the solution. That is, the reaction proceeds in the direction of decreasing OH ⁻ ions or increasing H ⁺ ions from the solution. Thus, OH alkaline solution ^- removed by the Zr-S adsorbent Sulfate ion (SO ₄ ^2-) is easily replaced, surfactants during the anion exchange reaction is forced out the pores Is done. In this case, the pH of the alkaline solution may be 8 to 13, but is preferably 9 to 12, and more preferably 10 to 12.

In this way, the surfactant can be removed. However, since an anion exchange reaction also occurs at this time, the sulfate ions (HSO ₄ ²⁻ and SO ₄ ²⁻ ) in the Zr—S adsorbent are reduced. Since this sulfate ion functions as an anion exchange site when removing boron and fluorine in the waste water, the anion exchange site is supplemented by treatment with an acid to enhance the adsorption performance.

  Even if the adsorption activity of the porous material that does not adsorb the substance to be adsorbed is small, the adsorption activity may be improved by treating with an acid and supplementing the anion exchange site.

Next, the adsorption reaction by the porous body is preferably caused to occur in a pH region substantially equal to the inverse logarithm value pKa of the acid dissociation constant (Ka) of the adsorbed substance. Taking boron as an example, boron B (OH) ₄ ^- to adsorb to the inorganic adsorbent in the form, pH is higher B (OH) ₄ high ^- and concentration increases, it boron adsorption amount increases accordingly When the pH exceeds 10, the OH ⁻ concentration also increases, and the adsorption becomes a competitive reaction of B (OH) ₄ ^— and OH ⁻ , so that the boron adsorption amount decreases. More specifically, when boron is contained alone, the amount of adsorption increases in the range of pH 8-12, and in particular, the amount of boron adsorbed increases in the range of pH 8-10. It is more preferable to perform the adsorption treatment in this range. In other words, it is considered that the adsorption reaction increases most when the adsorption reaction is caused in the pH range approximately equal to the inverse logarithm value pKa of the acid dissociation constant (Ka) of the substance to be adsorbed. By doing so, the amount of adsorption can be increased most.

  The porous body described above is an adsorbent for boron and fluorine, and adsorbed substances in the wastewater are adsorbed and removed by bringing the adsorbent into contact with the wastewater. For example, the adsorbent is prepared in pellets, granules, powders, etc., and the wastewater is passed through an adsorption tower filled with the adsorbent, thereby performing adsorption removal treatment of boron and fluorine contained in the wastewater.

  The porous body described above is not limited to removing boron and fluorine, but can be adsorbed as long as it is a substance that can take the form of anions in waste water. For example, harmful heavy metals present in wastewater can be adsorbed if they can take the form of anions, and when removing boron and fluorine, harmful heavy metals can be removed at the same time. Useful.

  The adsorbent after use, that is, the porous material that adsorbs the adsorbed substance may be regenerated and reused with an acid. Since the anion exchange site can be replenished while removing the adsorbed boron and fluorine by washing the porous body with an acid, the porous body can be reused, which is very economical.

Examples of the acid include sulfuric acid (H ₂ SO ₄ ), hydrochloric acid (HCI), nitric acid (HNO ₃ ), phosphoric acid (H ₃ PO ₄ ), and acetic acid (CH ₃ COOH), preferably sulfuric acid (H ₂ SO ₄ ), but not limited to these.

Next, in the regeneration of the porous zirconium body, when sulfuric acid (H ₂ SO ₄ ) is used, the concentration of the solution is made larger than 1.0 × 10 ⁻² mol / l and smaller than 1.0 mol / l. Preferably 7.5 × 10 ⁻² mol / l to 0.75 mol / l, more preferably 5.0 × 10 ⁻² mol / l to 0.5 mol / l, and even more preferably 0.25 ×. 10 ⁻² mol / l to 0.25 mol / l, most preferably 0.1 mol / l. In addition, a porous zirconium body elutes at 1.0 mol / l or more, and almost no regeneration is possible at 1.0 × 10 ⁻² mol / l or less. A good regeneration effect can be obtained at 0.1 mol / l.

  The above-described embodiment is an example of a preferred embodiment of the present invention, but is not limited thereto, and various modifications can be made without departing from the scope of the present invention.

  Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples.

[Example 1]
(1) Experiment (1.1) Tested Adsorbent In this experiment, two types of commercially available inorganic adsorbents (molecular sieve 13X (MS-13X) and activated carbon (AC)) and three prototype zirconium-based adsorbents were used. Used as an adsorbent. Further, in order to compare the boron adsorption performance, a boron selective ion exchange resin (Amberlite IRA743) was used.

(1.2) Preparation of Zirconium (Zr) Adsorbent Zr inorganic adsorbent was prepared by the following three methods. A reagent manufactured by Wako Pure Chemical Industries, Ltd. was used.
(A) Zr-S (hydrothermal synthesis, unfired)
A zirconium porous body (Zr-S) was prepared without performing the firing treatment and the phosphoric acid treatment. A solution of 2.5 g of hexadecyltrimethylammonium bromide ([CH ₃ (CH ₂ ) ₁₅ N (CH ₃ ) ₃ ] Br, CTMBr)) as a surfactant in 85 g of distilled water and zirconium sulfate (IV) in 15 g of distilled water ) A solution in which 4.55 g of tetrahydrate (Zr (SO ₄ ) ₂ .4H ₂ O) was dissolved was mixed and stirred at room temperature for 2 hours. Thereafter, the precipitate was matured by heating and maintaining at 373 K for 48 hours. The resulting precipitate was filtered and dried overnight at 373K. The dried solid was pulverized to obtain a white powder.

(B) Zr-M (hydrothermal synthesis, firing)
For the purpose of removing the CTMABr contained in the dry solid obtained by drying overnight in the procedure (a) by oxidative decomposition and creating pores, firing (oxidative decomposition treatment) was performed at 733 K in air for 5 hours. . The obtained fired solid was pulverized to obtain a white powder.

(C) Zr-N (nitrate decomposition)
Zirconium oxynitrate (ZrO (NO ₃ ) ₂ ) was calcined in air at 773 K for 3 hours to undergo oxidative decomposition. The obtained fired solid was pulverized to obtain a white powder.

(1.3) Adsorption Experiment A solution in which a predetermined amount of boric acid (H ₃ BO ₃ ) and sodium fluoride (NaF) were dissolved in distilled water was used for the adsorption experiment. 100 cm ³ of the solution was collected in an Erlenmeyer flask, and a predetermined amount (0.2 to 0.5 g) of an adsorbent was added thereto, followed by shaking at room temperature for 48 to 139 hours. In the boron adsorption experiment, an aqueous solution of sodium hydroxide (NaOH) or nitric acid (HNO ₃ ) was used to control the solution in the experiment to be constant at a predetermined pH. On the other hand, pH control was not performed in the fluorine adsorption experiment.

After the start of the adsorption experiment, 1 cm ³ of the adsorbed solution after a predetermined time passed was collected by passing through a 0.45 μm filter. This was diluted with distilled water (50 to 100 times), and the concentration of adsorbate and the like was measured with an ICP emission spectrometer. For some solution samples, ions in the solution were identified and quantified by ion chromatography. As an index of adsorption performance, the following adsorption amount per adsorbent weight and distribution coefficient (Kd) were used.

  The amount of adsorption per unit weight of the adsorbent was calculated from Equation 1 from the adsorbate concentration of the solution before and after the adsorption experiment.

ここで、Ｃ_０：吸着実験前の溶液中の微量元素濃度（ｍｇ・ｄｍ^−３）、Ｃ_１：吸着実験後の溶液中の微量元素濃度（ｍｇ・ｄｍ^−３）、Ｖ：使用した溶液量（ｃｍ^３）、Ｗ：使用した吸着剤量（ｇ）である。

Here, C ₀ : Trace element concentration in the solution before the adsorption experiment (mg · dm ⁻³ ), C ₁ : Trace element concentration in the solution after the adsorption experiment (mg · dm ⁻³ ), V: Solution used Amount (cm ³ ), W: amount of adsorbent used (g).

ここで、ｑ：吸着剤単位重量あたりの微量元素吸着量（ｍｇ・ｇ^−１）、ｃ：吸着平衡時における溶液１ｃｍ^３中の吸着質濃度（ｍｇ・ｄｍ^−３）である。 The distribution coefficient (Kd) was calculated by Equation 2.

Here, q is the amount of the trace element adsorbed per unit weight of the adsorbent (mg · g ⁻¹ ), and c is the adsorbate concentration (mg · dm ⁻³ ) in 1 cm ³ of the solution at the time of adsorption equilibrium.

(1.4) Measurement of physical properties of adsorbent The BET specific surface area of the adsorbent was measured by a flow-type single point method. Adsorption measurement of N ₂ was performed at liquid nitrogen temperature after removing adsorbed moisture in the sample by holding at 573 K in carrier gas (N ₂ / He = 30/70) for 1 hour. In the measurement of the pore size distribution, the sample was degassed for Zr-S and IRA743 at 373 K overnight.

  The FTIR analysis of the adsorbent was measured for permeation absorption by KBr tablet method.

For the crystal structure analysis (XRD) of the adsorbent, analysis was carried out under the conditions of CuKα, tube voltage 40 kV, tube current 100 mA, scanning speed 4.0 ° min ⁻¹ , using MXP18 manufactured by Mac Science. The analysis at a low angle of 2θ = 10 ° or less was performed using the FT method under the conditions of a step width of 0.002 to 0.006 ° and a counting time of 4 sec.

(2) Experimental results (2.1) Structure of Zr-S and Zr-M The XRD pattern of the prepared Zr-S is shown in FIG. In XRD on the high angle side (10-70 °), no sharp diffraction lines were observed, and broad peaks were observed at 20.3, 28.0, and 57.8 °. All observed peaks were assigned to Zr (SO ₄ ) ₂ or ZrO ₂ .

  In the XRD pattern on the low angle side of Zr-S, one sharp diffraction line (2θ = 2.200 °) and three broad diffraction lines (2θ = 3.672, 4.210, 5.531 °) are observed, The lattice spacing (d-spacing) was 4.01, 2.40, 2.10, and 1.60 nm, respectively. From the results of comparison with the boron removal performance of Zr-M, assuming that Zr-S has a hexagonal structure (hexagonal pore structure) similar to MCM41 of typical mesoporous silica, the observed diffraction lines are It is attributed to the reflection of (100), (110), (200), (200).

FIG. 2 shows an XRD pattern of Zr-M. On the high angle side, different from Zr-S, clear peaks were observed at 2θ = 30, 35, 50 and 60 °. The peaks at 2θ = 30 and 35 ° belong to Zr (SO ₄ ) ₂ and Zr (SO ₄ ) ₂ .5H ₂ O, respectively, and the peaks at 2θ = 50 and 60 ° belong to ZrO ₂ . On the low angle side, the four diffraction lines observed with Zr-S disappeared. This is considered to be a result of the disappearance of the peak attributed to hexagonal because the hexagonal structure that had existed in the case of unfired collapsed by firing and changed to ZrO ₂ or the like. That is, it is considered that the hexagonal structure has disappeared.

FIG. 3 shows the N ₂ adsorption isotherm and pore diameter distribution of Zr—S. Table 1 summarizes the physical properties of Zr-S and IRA743. The Zr-S pores immediately after preparation are considered to be filled with the surfactant used at the time of synthesis, but pretreatment to remove the surfactant in the pores while maintaining the pore structure The condition was unknown. For this reason, in the N ₂ adsorption measurement of Zr—S, pretreatment was performed at 373 K, but it is considered that there is some difficulty in data reliability. Considering this, it was found that although Zr-S has a smaller pore volume than the commercially available IRA743, the surface area is about 10 times larger and the pore diameter is larger.

(2.2) pH dependence of boron adsorption amount The pH dependence of the partition coefficient Kd of various adsorbents at a boron concentration of 200 mg · dm ⁻³ is shown in FIG.

  Although Kd of IRA743 slightly decreased in the strong alkali (pH 12) region, it showed almost the same value from the acidic region to the weakly alkaline region. On the other hand, Kd of each inorganic adsorbent is a low value in the acid / alkali region, but shows a maximum value around pH 9, and particularly in the case of Zr-S, it shows a value exceeding the value of IRA 743 over pH 9-10. It was.

(2.3) Boron adsorption isotherm For each adsorbent, the boron adsorption amount was measured using simulated waste water with boron concentrations of 10, 70, 100, 200 and 500 mg · dm ⁻³ , and adsorption under conditions of room temperature and pH 9 An isotherm was obtained. The obtained results are shown in FIGS. 5 and 6 together with results approximated by Equation 3 (Langmuir equation) and Equation 4 (Freundlich equation).

ここで、ｑ：吸着剤への吸着量、ｑｓ：飽和吸着量、ａ：吸着平衡定数、Ｃ：ホウ素濃度、ｋおよび１／ｎ：吸着定数である。

Here, q: adsorption amount to the adsorbent, qs: saturated adsorption amount, a: adsorption equilibrium constant, C: boron concentration, k and 1 / n: adsorption constant.

It was found that adsorbents other than MS-13X almost follow the Langmuir type and Freundlich type adsorption isotherms. In the concentration range where the equilibrium adsorption concentration exceeds 100 mg · dm ⁻³ , Zr—S showed the highest boron adsorption amount. The order of adsorption amount in this concentration range was Zr-S>IRA743>Zr-N≈Zr-M> AC.

  Zr-M and Zr-N are samples obtained by oxidative decomposition of different starting materials, but since there is no significant difference in the amount of boron adsorbed between them, the effect on the amount of boron adsorbing due to the difference in the starting materials of preparation is small. Conceivable. On the other hand, between Zr-S and Zr-M, as seen in the results of X-ray diffraction, there is a large difference in structure and a large difference in boron adsorption amount. It is considered that the difference in the amount of adsorbed boron may contribute to the presence or absence of the hexagonal structure.

(2.4) Comparison of treatment capacity for boron-containing water
Based on the adsorption constant obtained from the Freundlich type adsorption isotherm, an estimation of the amount of adsorbent necessary for the boron treatment was attempted in the case of using Zr-S and IRA743. In the estimation, a processing system as shown in FIG. 7 was assumed. In this system, 1) batch processing is performed in each reactor, 2) water to be processed is sent from the first stage reactor to the second stage reactor, and 3) a new adsorbent is added to the second stage reactor. It was assumed that the adsorbent that had been adsorbed in the second-stage reactor was added to the first-stage reactor.

ここで、Ｑ：処理水量、Ｗ：吸着剤量、Ｃ：ホウ素濃度、ｑ：吸着剤への吸着量である。但し、添字は各段を出たものを示す。 Equations 5-7 can be derived from the material balance of each stage of the system.

Here, Q is the amount of treated water, W is the amount of adsorbent, C is the boron concentration, and q is the amount adsorbed on the adsorbent. However, the subscripts indicate those that have gone out of each stage.

ｑ_３＝０であることから、数式６、７および８から数式９が得られる。

Ｃ_１は、この式に原水および処理水のホウ素濃度（Ｃ_０、Ｃ_２）を代入することにより求められる。さらに、数式７、８から導かれる以下の数式１０から、必要吸着剤量が求められる。 The amount of adsorption in each reactor is expressed as Equation 4 to Equation 8.

Since q ₃ = 0, Expression 9 is obtained from Expressions 6, 7, and 8.

C ₁ is obtained by substituting the boron concentration (C ₀ , C ₂ ) of raw water and treated water into this equation. Furthermore, the necessary adsorbent amount is obtained from the following formula 10 derived from formulas 7 and 8.

一段処理を仮定した場合について、同様にして必要吸着剤量を求める式を導出すると、数式１１のようになる。

When a single-stage process is assumed, an equation for obtaining the necessary adsorbent amount in the same manner is derived as shown in Equation 11.

The estimation was made for the case of removal from 300 mg · dm ⁻³ to 200 mg · dm ⁻³ . The obtained results are shown in Table 2 together with the adsorption coefficient used for the estimation. Adsorbent requirement when removed from 300 mg · ^{dm -3} by one stage process until the 200 mg · ^{dm -3} is, 3.68Q in Zr-S, because it is 8.84Q in IRA743, Zr-S is the IRA743 It can be seen that processing is possible with an amount of about 0.4 times. In addition, when removing in the same manner in the two-stage treatment, the necessary amount of the adsorbent is reduced from 3.68Q to 2.84Q in Zr-S, and the treatment can be performed in an amount about 20% less than that in the case of removing in the one-stage treatment. .

(2.5) Adsorption characteristics of Zr-S Among the inorganic adsorbents, the adsorption performance of fluorine (F) was evaluated for Zr-S which showed excellent results in boron adsorption.

Table 3 summarizes the adsorption test results of each element.

  The pH of the solution decreased after the start of adsorption, and the behavior varied depending on the type of adsorbate. In the case of fluorine adsorption, pH 5.9 to 6.2 before adsorption decreased to a maximum of pH 2.7 after adsorption. The higher the initial adsorption concentration, the higher the pH during equilibrium adsorption. In the case of boron adsorption, the pH of the solution under experiment was controlled at 10 with NaOH.

FIG. 8 shows an adsorption isotherm at 298K. The amount of adsorption could be arranged by Langmuir type adsorption isotherm. The saturated adsorption amount for boron was 56 mg-Bg ⁻¹ , which was twice as much as that of a commercially available ion exchange resin (IRA743, 23 mg-Bg ⁻¹ ). The saturation adsorption amount to fluorine Each 101 ^{mg-Fg -1,} and the partition coefficient was higher by more than one order of magnitude than that of boron adsorption (10 ² about) ⁽¹⁰ 3 ^{to 10} 4).

FIG. 9 shows the correlation between the amount of sulfur released from Zr-S and the amount of various trace elements adsorbed in the adsorption experiment. The graph also shows lines where the relationship between the amount of sulfur and the amount of adsorption is 1: 1 and 1: 2. Since the sulfur content measured by ICP-AES and _SO ^{4 2-amount} determined by ion chromatography were almost the same, Zr-S sulfur released from the sulfate ion in solution _(SO ^{4 2-and} HSO ₄ ^-) as I found it.

  As is clear from the figure, regardless of the type of adsorbate, the amount of trace elements increased as the amount of sulfur released increased. In the case of boron adsorption, the data variation was large, but when the amount of released sulfur is small, the relationship between the amount of sulfur and the amount of adsorbed boron is 1: 1, whereas when the amount of released sulfur is large, the relationship is 1: 2. The tendency to become was recognized. On the other hand, in the case of fluorine adsorption, it was found that the amount of sulfur released and the amount of adsorption are in a relationship of approximately 1: 2.

  From the above, macroscopically, in the case of fluorine adsorption, sulfur and fluorine in Zr—S are exchanged at a ratio of 1: 2, whereas in the case of boron, it is 1: 1 or depending on the amount of released sulfur. It was suggested that boron and sulfur exchange at 1: 2.

Under the experimental conditions of this experiment, boron and fluorine are present as monoanions (B (OH) ₄ ⁻ and F ⁻ , respectively). For this reason, in the case of fluorine, it is suggested that F ⁻ ions exchange with SO ₄ ²⁻ ions at a ratio of 2: 1. Regarding boron, B (OH) ₄ ⁻ and HSO ₄ ⁻ are exchanged by 1: 1 when the amount of released sulfur is small, and 1: 2 due to B (OH) ₄ ⁻ and SO ₄ ²⁻ when the amount of released sulfur is large. It is interpreted that the exchange will prevail.

In order to verify the validity of the above estimation, an infrared absorption analysis of Zr-S was performed before and after the boron adsorption experiment. FIG. 10 shows the FTIR spectrum. In the spectrum before adsorption (FIG. 10 (a)), absorption attributed to SO ₄ ²⁻ (1100 cm ⁻¹ ) and absorption attributed to HSO ₄ ⁻ (1240, 1140, 1000 cm ⁻¹ ) were observed. . That is, it was confirmed that SO ₄ ²⁻ and HSO ₄ ⁻ exist as functional groups containing S in Zr—S. Also, methyl group (CH ₃ ^-) and a methylene group ^(- CH ₂ -) from the absorption (2930,2850,1640,1480cm ^-1) was observed to be attributable to mesopores during synthesis of Zr-S It was found that the surfactant (CTMBr) used as a template for forming sapphire remained in Zr-S.

On the other hand, the absorption (2930, 2850, 1640, 1480 cm ⁻¹ ) attributed to CTMABr is reduced in the spectrum of Zr—S after adsorbing boron (FIG. 10B). Part was dissolved and desorbed from Zr-S. This was supported by CNS analysis of Zr-S before and after the adsorption experiment. Therefore, it was confirmed that the substance to be adsorbed can be adsorbed even if CTMBr as a template remains in the Zr-S pores.

In addition, the absorption attributed to SO ₄ ²⁻ and HSO ₄ ⁻ decreased by the adsorption experiment, and broad absorption (1350 cm ⁻¹ ) attributed to the B—O stretching vibration appeared. This suggests that HSO ₄ ⁻ and SO ₄ ²⁻ exchange ions with B (OH) ₄ ⁻ . That is, it was suggested that the adsorption of anions present in water to Zr—S proceeds by anion exchange with sulfate ions on the Zr—S pore surface.

[Example 2]
Using the same lot of Zr-S adsorbent as in Example 1, 0.5 g was weighed, one was used as it was (Sample A), and one was washed twice with distilled water to remove the surfactant. Used later (Specimen B). As a result of reaction for 48 hours under the conditions of boron concentration of 200 ppm and pH of 9, boron adsorption amount per unit weight was A = 11.8 mg / g, B = 8.5 mg / g, and no significant difference was observed. From this result, it was confirmed that the surfactant in the pores could be removed even if the Zr—S adsorbent was washed with distilled water. Further, it was confirmed that even if the surfactant is present in the pores, the adsorption ability is not particularly affected.

[Example 3]
In Example 1, the adsorption characteristics of boron and fluorine were investigated, but the anion concentration range to be investigated was very small. Therefore, in order to confirm the results obtained in Example 1 and to obtain data with higher reliability, the present Example was further investigated in a wide range of anion concentrations and pH.

(1). Adsorption Experiment A solution prepared by dissolving a predetermined amount of boric acid (H ₃ BO ₃ ) and sodium fluoride (NaF) in distilled water was used for the adsorption experiment. In order to accurately measure the saturated adsorption amount, the anion concentration was changed in the range of 50 to 1500 mgdm ⁻³ . 100 cm ³ of the solution was collected in a plastic sample container, and a predetermined amount (0.1 to 1.0 g) of Zr—S was added thereto, followed by shaking at room temperature (293 to 298 K) for 24 to 48 hours. In the boron adsorption experiment, an aqueous solution of sodium hydroxide (NaOH) or nitric acid (HNO ₃ ) was used to control the solution in the experiment at a predetermined pH. On the other hand, pH control was not performed in the fluorine adsorption experiment.
Furthermore, the adsorption characteristics in the case of pH 2 to 12 and pH 2 to 9 were investigated with boric acid (H ₃ BO ₃ ) and sodium fluoride (NaF) concentrations of 500 mgdm ⁻³ .

After the start of the adsorption experiment, 1 cm ³ of the adsorbed solution after a predetermined time passed was collected by passing through a 0.45 μm filter. This was diluted with distilled water (25 to 100 times), and the concentration of adsorbate and the like was measured with an ICP emission spectrometer. For some solution samples, ions in the solution were identified and quantified by ion chromatography. By tracking the time course of the anion concentration during adsorption, the consistency and reproducibility of the obtained data were confirmed.

  Next, FTIR analysis (permeation absorption measurement by KBr tablet method) was performed on Zr-S before and after boron and fluorine adsorption experiments.

(2). Experimental results (boron)
FIG. 11 shows an adsorption isotherm of boron at pH 9-10. The adsorption isotherm can be arranged by the Langmuir type adsorption equation, and the saturated adsorption amount was estimated to be 80 mg-Bg- ¹ . At this time, it was estimated that the amount of boron adsorbed and the sulfate ions released from Zr-S were approximately 1: 1 in molar ratio.
FIG. 12 shows the amount of boron adsorbed at pH 2-12. The amount of boron adsorbed was maximum at pH 8 to 11, and decreased significantly on the acidic side and alkaline side. Boric acid has a pKa of 9.24, and at this point, H ₃ BO ₃ is the dominant chemical species on the low pH side, and B (OH) ₄ ⁻ is the dominant chemical species on the high pH side. For this reason, it is interpreted that a high Kd is exhibited at pH 8 to 11 where borate ions exchangeable with sulfate ions in Zr-S start to be generated. On the other hand, in this higher-pH, B (OH) ₄ ^- and OH ^- adsorption amount to the competitive adsorption of it is understood that reduced.
From the experimental results shown in FIG. 12, the boron adsorption amount, the SO ₄ ²⁻ release amount from Zr—S, and the molar ratio between the boron adsorption amount and the SO ₄ ²⁻ release amount (B / SO ₄ ^{2 -} ) The amount of boron adsorbed showed the maximum value at pH 8-11 and decreased significantly at the pH before and after that, whereas the amount of sulfate ion released from Zr-S increased with pH and became almost constant from around pH 9.
FIG. 14 shows FTIR spectra of Zr-S before and after the adsorption experiment. Absorption attributed to SO ₄ ²⁻ (1100, 640 cm ⁻¹ ) and absorption attributed to HSO ₄ ⁻ (1240, 1140, 1000 cm ⁻¹ ) are decreased by the adsorption experiment and attributed to B—O stretching vibration. Broad absorption (1350 cm ⁻¹ ) appeared. This suggested that HSO ₄ ⁻ and SO ₄ ²⁻ exchanged ions with B (OH) ₄ ⁻ . In Example 1, for boron, B (OH) ₄ ⁻ and HSO ₄ ⁻ are exchanged at 1: 1 when the amount of released sulfur is small, and B (OH) ₄ ⁻ and SO ₄ ² when the amount of released sulfur is large. ^- According to the 1: 2 of the exchange it has been interpreted to be the predominant. That is, from this result, Zr-S is a borate ions shown to adsorb by anion exchange with sulfate ion, B _{(OH) 4} ^- and HSO ₄ ^- For 1: 1, B (OH ) ₄ ^- when the _SO ^{4 2-one:} the anion exchange occurs was suggested by two.

(3). Experimental results (fluorine)
FIG. 15 shows the adsorption isotherm of fluorine at 298 K and pH 2-8. Since the pH was not adjusted during the experiment, the pH at the time of adsorption equilibrium varied between 2 and 8. Similarly to the case of boron, the fluorine adsorption was in accordance with the Langmuir type adsorption formula, and the saturated adsorption amount was estimated to be 115 mg-Fg- ¹ . The amount of sulfate ions released from Zr-S during adsorption and the amount of fluorine adsorbed were approximately 1: 2.
FIG. 6 shows the amount of fluorine adsorption at pH 2-9. Similar to the case of boron, it showed a mountain-shaped distribution in which the adsorption amount was maximum near the acid dissociation constant.
In the FTIR spectra (not shown) of Zr-S before and after fluorine adsorption, the absorption attributed to sulfate ions decreased with an increase in the amount of adsorbed fluorine. Therefore, it is considered that fluorine and sulfate ions were anion exchanged. Although the infrared absorption due to the fluorine bond is considered to exist at 1200 to 1400 cm ⁻¹ , the confirmation was difficult due to the small absorption intensity.

As described above, the following knowledge was obtained from the experimental results of Example 3.
(A) Similar to the results obtained in Example 1, the porous zirconium compound Zr-S exhibits high adsorption performance for boron and fluorine in water, and a wider range of anion concentrations than in Example 1. As a result, the saturated adsorption amounts estimated from the Langmuir type adsorption isotherm were 80 mg-Bg ⁻¹ and 115 mg-Fg ⁻¹ , respectively.
(B) It was confirmed that anion adsorption proceeds by anion exchange with sulfate ions in Zr-S.

[Example 4]
(1) Experiment In Example 1, it was suggested that the adsorption of anions present in water to Zr-S proceeds by exchange of sulfate ions and anions on the inner surface of Zr-S pores. Therefore, the conditions for regeneration of Zr-S on which boron was adsorbed were examined using four types of sulfuric acid solutions and one type of sodium sulfate solution with different concentrations.

(1.1) Zr-S adsorption / regeneration experiments As Zr-S adsorption / regeneration experiments, boron adsorption experiments using a boric acid solution and various regenerations for desorbing and regenerating boron from Zr-S after boron adsorption The solution was examined. Zr-S regeneration solutions include four types of sulfuric acid solutions (1 × 10 ⁻³ mol / l, 1 × 10 ⁻² mol / l, 0.1 mol / l and 1.0 mol / l) having different concentrations and 1 A 0.0 mol / l sodium sulfate solution was used. Adsorption of boron was performed by adding Zr-S to a 100 mg ³ 500 mg / l boric acid solution and shaking at room temperature for 24 hours. On the other hand, Zr-S regeneration experiment was performed by filtering and drying Zr-S after boron adsorption, adding it to 100 cm ³ regeneration solution, and shaking for 3 hours at room temperature. Two regeneration cycles were performed (1 adsorption → 2 regeneration → 3 adsorption → 4 regeneration). In addition, 1 g of Zr—S was provided at the start of the adsorption experiment.
Boron adsorption / desorption characteristic data was obtained as follows. First, 1 cm ³ of the adsorbed solution that had passed a predetermined time was collected through a 0.45 μm filter. This was diluted with distilled water (50 to 100 times), and the concentration of adsorbate and the like was measured with an ICP emission spectrometer. In addition, the amount of adsorption and the amount of release per unit weight of the adsorbent were calculated using Formula 1 described in Example 1. It should be noted that Formula 1 can also be applied to the case where regeneration is performed. In this case, C _o : the concentration of trace elements in the solution before the regeneration experiment (mg · dm ⁻³ ), C ₁ : in the solution after the regeneration experiment Trace element concentration (mg · dm ⁻³ ), V: amount of solution used (cm ³ ), W: amount of adsorbent used (g).
The change in the weight of the adsorbent was measured by weighing the dry adsorbent obtained by drying the adsorbent overnight at 90 ° C. before and after the adsorption or regeneration treatment.

(1.2) Physical property analysis Zr-S after boron adsorption and this with 1 × 10 ⁻³ mol / l, 1 × 10 ⁻² mol / l, 0.1 mol / l and 1.0 mol / l sulfuric acid solutions The regenerated Zr-S was subjected to FTIR analysis (permeation absorption measurement by KBr tablet method).

(1.3) CHN analysis in Zr-S pores In the synthesis of Zr-S, in order to form a uniform pore structure in Zr-S, a surfactant (CTMBr) is used as a template for pore formation. Use. For this reason, it is thought that Zr-S immediately after preparation is in a state in which CTMABr is filled in the pores. In order to confirm this, carbon, hydrogen, and nitrogen analysis (CHN analysis: CHNS analyzer PE2400, Perkin Elmer) of Zr-S was performed.

(1.4) Elution behavior of surfactant from inside Zr-S pore It was confirmed in Example 2 that the surfactant could hardly be removed by washing the Zr-S adsorbent with distilled water. Therefore, in order to confirm the behavior of elution of CTMABr from Zr-S, Zr-S was dispersed in 100 cm ³ of pure water, the pH was changed variously, and sulfate ions were converted into total organic carbon by ICP emission analysis. The elution amount of CTMABr was measured with a meter. In addition, pH was changed using sodium hydroxide (NaOH) aqueous solution or nitric acid (HNO ₃ ).

(2) Experimental results (2.1) Adsorption / desorption experiment on Zr-S Table 5 shows the results of Zr-S boron adsorption / regeneration experiment, and FIG. 11 shows various concentrations of sulfuric acid solution and sodium sulfate solution 1.0 mol. The results of the boron adsorption / regeneration experiment using a / l regeneration solution are shown. The low concentration sulfuric acid solution (1 × 10 ⁻³ , 1 × 10 ⁻² mol / l) had a small amount of boron desorption during adsorbent regeneration. Further, even when a 1.0 mol / l sodium sulfate solution was used, the amount of boron desorption during regeneration of the adsorbent was small. On the other hand, when a 1.0 mol / l sulfuric acid solution was used, although the amount of boron desorption was large, zirconium which is a constituent element of Zr—S was also eluted at the same time. On the other hand, when a 0.1 mol / l sulfuric acid solution was used, a boron desorption amount comparable to that of a 1.0 mol / l sulfuric acid solution was exhibited, and no elution of zirconium was observed. Therefore, in the regeneration of the used adsorbent, it is considered that there is an optimum concentration value of the sulfuric acid solution in 1 × 10 ⁻² to 1.0 mol / l. If a 0.1 mol / l sulfuric acid solution is used, It was confirmed that good reproduction characteristics can be obtained. In a regeneration experiment using a 1.0 mol / l H ₂ SO ₄ solution and a 1.0 mol / l Na ₂ SO ₄ solution, the data is missing because the SO ₄ ²⁻ concentration is high and exceeds the measurement range.

(2.2) Weight evaluation of Zr-S As shown in FIG. 11, the weight of Zr-S recovered after the first adsorption experiment was about 60% before the experiment. Furthermore, the weight of Zr—S recovered after each adsorption / regeneration was reduced to 10-30% before the experiment. Of the reconstituted solutions examined, the recovery rate was highest when a 0.1 mol / l sulfuric acid solution was used.

(2.3) FTIR Analysis Results FIG. 12 shows FTIR spectra of Zr—S before and after regeneration in a regeneration experiment using a 0.1 mol / l sulfuric acid solution. In the adsorption experiment, the absorption attributed to sulfate ions (1240, 1140, 1100, 1000, 640 cm ⁻¹ ) decreased and the absorption attributed to boron (1350 cm ⁻¹ ) was generated. On the other hand, in the regeneration experiment, it was observed that the absorption of boron disappeared and the absorption of sulfate ions increased remarkably, and it was found that sulfate ions were introduced into Zr-S by the regeneration treatment. Similarly, when 1.0 mol / l sulfuric acid was used, sulfate ions were introduced into Zr-S by the regeneration treatment. On the other hand, when 1 × 10 ⁻³ mol / l and 1 × 10 ⁻² mol / l sulfuric acid solutions were used, absorption of sulfate ions of Zr—S after treatment was not completely recovered. From the above, in the regeneration of the used adsorbent, there is an optimum sulfuric acid solution concentration value of 1 × 10 ⁻² to 1.0 mol / l, and if a 0.1 mol / l sulfuric acid solution is used, It was confirmed that good reproduction characteristics can be obtained.

(2.4) CHN analysis results in Zr—S pores Table 6 shows the results of Zr—S carbon, hydrogen, and nitrogen analysis (CHN analysis). The prepared Zr-S contained 31.0 wt% carbon and 1.9 wt% nitrogen, and the carbon / nitrogen ratio (C / N ratio) was consistent with that of CTMABr. On the other hand, the carbon / hydrogen ratio (C / H ratio) is 4.6, which is slightly different from the value of CTMABr, which is considered to be due to the fact that the sensitivity of hydrogen measurement is not so high. From the above, it was concluded that the carbon content in Zr-S was due to CTMABr, and based on this, the content of CTMABr in Zr-S was estimated to be 49.5 wt%.

(2.5) Elution Behavior of Surfactant from Inside Zr-S Pore Next, the result of confirming the elution behavior of CTMABr from Zr-S is shown in FIG. In the figure, the symbol ◯ is CTMABr and the symbol Δ is SO ₄ ^2- . It was confirmed that the elution amount of CTMABr and sulfate ions was increased by raising the pH of the solution. In addition, since the molar ratio of eluted sulfate ion to CTMABr (SO ₄ ²⁻ / CTMABr) was about 2.5 to 3 regardless of the amount of elution, CTMABr was dissolved in water accompanied by sulfate ions. Guessed. At pH 10 to 12, the elution amount of CTMABr reached 0.8 to 0.9 mmolg ⁻¹ , and it was estimated that 0.3 g of CTMABr was released with respect to 1 g of Zr—S.
In order to confirm this result, the carbon concentration eluted in the adsorption / desorption experiment was measured with a total organic carbon meter. Assuming that the eluted carbon is CTMABr, the contribution of elution of CTMABr and anion exchange between boron and sulfate ions to the weight loss of Zr-S before and after the experiment was evaluated. The results are shown on the right side of Table 4. In the first adsorption / regeneration cycle in the table (1 adsorption → 2 regeneration), it is estimated that 70 to 80% of the observed weight loss of Zr-S is due to ion exchange accompanying elution and adsorption / desorption of the surfactant. It was lost. Considering the recovery loss of Zr-S due to the experimental operation, it is presumed that the decrease in the weight of Zr-S due to the adsorption experiment is due to the elution of the surfactant CTMABr from the Zr-S pores. . Therefore, if the CMABr filled in the pores can be removed while maintaining the pore structure and adsorption capacity of Zr-S, the area for adsorbing the adsorbed substance in the pores is increased, and the CTABr content is also increased. Since it was estimated from the CHN analysis result that the amount was 49.5 wt%, it is conceivable that the adsorption performance per unit weight is improved by a factor of 2 by removing this CTMABr content.

As described above, the following knowledge was obtained from the experimental results of Example 4.
(A) In the regeneration of the used adsorbent adsorbed with boron, it is considered that there is an optimum concentration value of the sulfuric acid solution in the range of 1 × 10 ⁻² to 1.0 mol / l, and the 0.1 mol / l sulfuric acid solution Good reproduction characteristics were obtained using.
(B) In the case of boron adsorption, it was confirmed from the FTIR measurement results of Zr—S that borate ions and sulfate ions were reversibly exchanged by the adsorption / regeneration cycle.
(C) Zr-S contains about 50 wt% of a surfactant as a template for forming a pore structure. It was suggested that the weight loss of Zr—S observed before and after the adsorption experiment was attributed to surfactant elution and ion exchange. Therefore, by contacting Zr-S with an alkaline solution and then treating with sulfuric acid, by removing CTMBr filled in the pores while maintaining the pore structure and adsorption ability of Zr-S, It is conceivable that the adsorption capacity can be improved as compared with the case where the surfactant is not removed.

The XRD pattern of prepared Zr-S is shown, (a) is a figure which shows the XRD pattern of the low angle side, (b) is a figure which shows the XRD pattern of the high angle side. The XRD pattern of prepared Zr-M is shown, (a) is a figure which shows the XRD pattern of the low angle side, (b) is a figure which shows the XRD pattern of the high angle side. (A) is a figure which shows the desorption isotherm of Zr-S, (b) is a figure which shows pore diameter distribution of Zr-S. It is a figure which shows the pH dependence of the distribution coefficient Kd of various adsorbents. The symbol ◯ is porous zirconium (Zr-S), the symbol Δ is a commercially available ion exchange resin (IRA-743), the symbol □ is a thermal decomposition of zirconium oxynitrate (Zr-N), and the symbol ▽ is zeolite (13X). The symbol ◇ is activated carbon (AC). It is a figure which shows the adsorption isotherm of each adsorbent. The symbol ◯ is porous zirconium (Zr-S), the symbol Δ is a commercially available ion exchange resin (IRA-743), the symbol □ is thermal decomposition of zirconium oxynitrate (Zr-N), and the symbol ▽ is zeolite (MS- 13X), symbol ◇ is activated carbon (AC), symbol ● is calcined porous zirconium (Zr-M). It is a figure which shows the adsorption isotherm regarding various adsorbents. Symbol ○ indicates porous zirconium (Zr-S), symbol ● calcined porous zirconium (Zr-M), symbol □ indicates thermal decomposition of zirconium oxynitrate (Zr-N), and symbol Δ indicates commercially available ion exchange. Resin (IRA-743), symbol ▽ is zeolite (MS-13X), symbol ◇ is activated carbon (AC). It is a figure which shows a processing system. It is a figure which shows the adsorption isotherm (298K) of the liquid phase trace element in Zr-S. It is a figure which shows the correlation of the amount of sulfur discharge | released from Zr-S, and adsorption amount. The FTIR spectrum of Zr-S is shown, (a) is a figure immediately after preparation (before boron adsorption experiment), (b) is a figure after boron adsorption experiment. It is a figure which shows the adsorption | suction isotherm (298K) of boron in Zr-S. It is a figure which shows the pH dependence of the boron adsorption amount in Zr-S. It is a figure which shows the pH dependence of the boron adsorption | suction characteristic in Zr-S. The symbol ◯ is the B adsorption amount, the symbol ● is the SO ₄ ² adsorption amount, and the symbol □ is the B / SO ₄ ² ratio. It is a figure which shows the FTIR spectrum of Zr-S in a boron adsorption experiment. It is a figure which shows the adsorption | suction isotherm (298K) of the fluorine in Zr-S. It is a figure which shows the pH dependence of the fluorine adsorption amount in Zr-S. It is a figure which shows a boron adsorption | suction and reproduction | regeneration experimental result. The symbol Δ is the weight before the test, and the symbol ▽ is the weight after the test. It is a figure which shows the FTIR spectrum of Zr-S before and behind reproduction | regeneration in the reproduction | regeneration experiment using a 0.1 mol / l sulfuric acid solution. It is a figure which shows the surfactant eluting from Zr-S and the amount of sulfate ions. The symbol ◯ is CTMABr, and the symbol Δ is SO ₄ ^2- .

Claims (4)

A wastewater treatment method in which at least one of boron and fluorine is an adsorbed substance, and the wastewater containing the adsorbed substance is contacted with a porous body mainly composed of zirconium to adsorb and remove the adsorbed substance. The method for treating waste water, wherein the porous body is made of a surfactant as a template, the surfactant in the pores is removed with an alkali, treated with an acid, and then contacted with the waste water.   The wastewater treatment method according to claim 1, wherein the porous body has a hexagonal structure. The wastewater treatment method according to claim 1 or 2, wherein an adsorption reaction is caused in a pH range substantially equal to an inverse logarithm value pKa of the acid dissociation constant (Ka) of the adsorbed substance . The wastewater treatment method according to any one of claims 1 to 3, wherein the porous body that has adsorbed the adsorbed substance is regenerated and reused with an acid .

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