JP2007000752A - High-speed arsenic adsorbing material and method for producing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a high-speed arsenic adsorbing material by which arsenic can be removed at the SV (space velocity) higher than 10 h<SP>-1</SP>and a large quantity of the water to be treated can be treated quickly. <P>SOLUTION: The high-speed arsenic adsorbing material is obtained by performing the adsorption of a trivalent iron on an iminodiacetate group of a fibrous iminodiacetate group-containing adsorbing material and conditioning the iron-adsorbed adsorbing material in an acidic solution. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to removing arsenic contained in groundwater or river water.

The following technical documents already exist as techniques for removing arsenic.
(1) A 50 mM ferric chloride solution adjusted to pH 3.5 is poured into a sodium-type Unitika UR-10 (iminodiacetic acid type resin) in a solution, followed by washing with water. The loading amount of iron was 1.84 mmol / g. When SV = 7 h ⁻¹ and pH 8.4 and 100 ppm of arsenic acid were flowed, the adsorption amount of arsenic was 0.24 mmol / g. (Non-Patent Document 1)
(2) A 100 mM ferric chloride solution adjusted to pH 2.0 is passed through Bayer TP-207 (iminodiacetic acid type resin). The amount of iron loaded was 2.15 to 2.7 mmol / g. When this was immersed in a 1000 ppm arsenic acid solution, the adsorption amount of arsenic was 0.45 mmol / g at pH 1.8. (Non-Patent Document 2)
Separation Science and technology, 13 (2) 173-184 (1978) Reactive & Functional Polymers 54 (2003) 85-94

As a method for removing arsenic other than the above-mentioned literature, a commercially available activated alumina arsenic adsorbent (Sumitomo Chemical KHD-12SR) is packed in a column, and a solution containing arsenic is flowed to remove arsenic in the solution. Remove. In this case, the breakthrough capacity is 0.0076 mmol / g-alumina when the space velocity of 20 ppm arsenic acid solution (SV: the flow rate per hour based on the packing capacity of the adsorbent is 10 h ^-1 ). Met. Furthermore, when SV was set to 100 h ⁻¹ , the breakthrough capacity was reduced to 0.0010 mmol / g-alumina, and the arsenic removal performance was significantly reduced.

Therefore, if arsenic can be removed under conditions where SV is higher than 10h ⁻¹ , a large amount of treated water can be treated quickly.

Means for Solving the Invention

Trivalent iron was supported on the fibrous iminodiacetic acid type adsorbent under the two conditions described in the above-mentioned non-patent document, and the adsorption characteristics of arsenic acid were evaluated. However, arsenic could not be adsorbed. Therefore, in the present invention, trivalent iron is dissolved in an acetic acid buffer having a pH of 5.5, a 100 mg / solution is prepared, and the iron is supported by flowing through a column packed with a fibrous iminodiacetic acid type adsorbent. After that, the adsorbent for arsenic was prepared by conditioning at pH 2.5.
[The invention's effect]

  The removal of arsenic contained in groundwater or river water by the adsorbent of the present invention makes it possible to rapidly process a large amount of treated water by performing the treatment at high speed.

The fibrous iminodiacetic acid type adsorbent was prepared by a graft polymerization method. The nonwoven fabric was irradiated with an electron beam or gamma ray at 20 to 200 kGy in a nitrogen atmosphere, immersed in a 10/90 vol% glycidyl methacrylate (GMA) dimethyl sulfoxide (DMSO) solution, and graft-polymerized at 40 ° C. for 2 hours. A methanol solution or a surfactant solution (Japanese Patent Application No. 2004-167017) can be used in place of DMSO. Sodium iminodiacetate (NH (CH ₂ COONa) ₂ ) was dissolved in a solvent in which DMSO and pure water were mixed at a volume ratio of 1: 1 so that the concentration thereof was 0.425M. To this solution, GMA reacted for 20 hours at 80 ° C. The grafted nonwoven fabric, Iminoni acetate groups; was introduced (IDA group _{-N (CH 2 COOH) 2)} . The nonwoven fabric after introduction of IDA groups was reacted with 0.5 M sulfuric acid at 80 ° C. for 2 hours to convert unreacted epoxy groups to diol groups and to change Na-form imino-acetic acid groups to H-form. In the case of DMSO, the grafting rate was 170% after 2 hours of reaction, and the amount of iminoniacetic acid group introduced was 2.1 mmol / g-adsorbent. An acetate buffer was prepared so as to have a pH of 5.5, and iron (III) chloride hexahydrate (FeCl3 · 6H2O) was dissolved using the acetate buffer as a solvent to prepare a 100 mg / l-Fe solution. The conditioning condition is pH 0.5-3, with 2.5-3.0 being preferred. Hereinafter, the present invention will be described based on examples.

Example 1
As a result of immersing in a 100 mg / l-Fe3 + solution at pH 5.5 for 24 hours and supporting Fe3 + on the iminodiacetic acid adsorbent, it was possible to support 1.7 mmol / g-adsorbent Fe3 ⁺ . As a result of conditioning this adsorbent with a solution of pH 0.5-3, the one that was conditioned at pH 2.5 was able to adsorb the most As (Fig. 1). Under these conditions, the amount of Fe3 ⁺ supported was 1.5 mmol / g-adsorbent, and arsenic of 0.15 mmol / g-adsorbent could be adsorbed.
(Example 2)
As a result of passing a pH 7 As solution (20 mg / l) with SV = 10h ^-1 using commercially available activated alumina as the adsorbent, and with the fibrous arsenic adsorbent of the present invention at SV = 100h ^-1 FIG. 2 shows the breakthrough characteristics in the removal of arsenic in the case where the arsenic is removed.

In the case of alumina, the breakthrough point was 28 in terms of the flow rate, and 39 in the fibrous arsenic adsorbent of the present invention. In the case of alumina, when SV is set to 100 h ⁻¹ , the breakthrough point is 4 in terms of the flow rate, and arsenic cannot be removed under these conditions. In contrast, the adsorption amount per unit weight of the fibrous arsenic adsorbent during breakthrough of the present invention is 10 times that of alumina, 0.073 mmol / g, and 1.5 times that of alumina even per volume (the outflow rate / capture shown in FIG. 2). In the volume of collected material, the breakthrough point of alumina was about 100, and the breakthrough point of the cloth-like adsorbent agent of the present invention was about 150 mmol / l.

In FIG. 2, C / C ₀ represents the ratio of the outlet and inlet concentrations when the arsenic solution is poured into the adsorbent packed in the column. In the state C / C ₀ is 0, arsenic is collected by the adsorbent and eventually indicate that arsenic can not be adsorbed to reach adsorption capacity appears to the outlet, C / C ₀ increases. Also, the above breakthrough point usually represents when C / C ₀ is 0.05, and the horizontal axis is (flow rate / adsorbent volume), so the amount of adsorbed arsenic at the breakthrough point is
The concentration can be calculated by (concentration × (outflow rate / adsorbent volume) × adsorbent volume). When this amount is converted to mol and divided by the weight of the collection material, 0.073 mmol / g is obtained.

  According to the present invention, since arsenic can be removed at a high speed, a small arsenic removing device can be manufactured, which may be used for purifying rivers and groundwater.

It is a figure which shows the influence on the arsenic adsorption amount of conditioning pH. It is a figure which shows the comparison of an alumina and cloth-like adsorption material.

Claims (5)

  A high-speed arsenic adsorbing material obtained by adsorbing trivalent iron to a fibrous iminodiacetic acid group type adsorbent and then conditioning with an acidic solution.   A fibrous base material is subjected to radiation graft polymerization using a polymerizable monomer as a polymerization side chain, an iminodiacetic acid group is introduced into the graft polymerization side chain, and trivalent iron is adsorbed to the iminodiacetic acid group, and then an acidic solution. To make high-speed arsenic adsorbent by conditioning in   The process according to claim 2, wherein the polymerizable monomer is glycidyl methacrylate, allyl glycidyl ether or (chloromethylstyrene).   The method according to claim 2, wherein the fibrous base material comprises a nonwoven fabric, a woven fabric, or a fiber made of polyethylene, polypropylene, or cellulose. After the radiation treatment of the fibrous base material, the fibrous base material is brought into contact with a glycidyl methacrylate-containing solution and grafted onto the base material using glycidyl methacrylate as a side chain, and the base material into which the graft side chain has been introduced is brought into contact with the sodium iminodiacetate solution. After introducing the iminodiacetate Na group into the side chain, it is reacted with an acidic solution to convert the unreacted glycidyl methacrylate side chain epoxy group to a diol group, and the Na-form iminodiacetic acid group is converted to the H-form. The method according to claim 2, wherein the iminoniacetic acid group is converted to a trivalent Fe form by contacting with an iron (III) -containing solution, and then the pH is adjusted with an acidic solution having a pH of 0.5-3.

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