WO2016076335A1 - Method and device for removing arsenic - Google Patents

Method and device for removing arsenic Download PDF

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WO2016076335A1
WO2016076335A1 PCT/JP2015/081663 JP2015081663W WO2016076335A1 WO 2016076335 A1 WO2016076335 A1 WO 2016076335A1 JP 2015081663 W JP2015081663 W JP 2015081663W WO 2016076335 A1 WO2016076335 A1 WO 2016076335A1
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arsenic
solution
liquid
ion exchanger
weakly acidic
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PCT/JP2015/081663
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French (fr)
Japanese (ja)
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稔 寺田
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株式会社エヴァテック研究所
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    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00—Treatment of water, waste water, or sewage
    • C02F1/28—Treatment of water, waste water, or sewage by sorption
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00—Treatment of water, waste water, or sewage
    • C02F1/42—Treatment of water, waste water, or sewage by ion-exchange
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00—Treatment of water, waste water, or sewage
    • C02F1/58—Treatment of water, waste water, or sewage by removing specified dissolved compounds
    • C02F1/62—Heavy metal compounds
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00—Treatment of water, waste water, or sewage
    • C02F1/72—Treatment of water, waste water, or sewage by oxidation

Definitions

  • the present invention relates to a method and apparatus for removing arsenic from a liquid such as groundwater.
  • groundwater The main forms of groundwater are arsenic acid (H 3 AsO 4 ) and arsenous acid (H 3 AsO 3 ), which are inorganic, and exist in an ionic form. Since groundwater is in a reducing environment, arsenic in groundwater often exists in the form of arsenite ions with an oxidation number of 3. It is known that arsenite has higher solubility than arsenate and inferior adsorbability to the adsorbent. For example, activated alumina (Al 2 O 3 ), iron-based compounds such as iron hydroxide, and cerium oxide are known as arsenic removal agents, but in this case as well, arsenite ions are hardly adsorbed on activated alumina.
  • activated alumina Al 2 O 3
  • iron-based compounds such as iron hydroxide
  • cerium oxide are known as arsenic removal agents, but in this case as well, arsenite ions are hardly adsorbed on activated alumina.
  • adsorbents such as activated alumina (Al 2 O 3 ), iron-based compounds and cerium oxide have a high adsorption rate at a weakly acidic to neutral pH.
  • Patent Document 1 describes that arsenic is oxidized by arsenite oxidizing bacteria. However, dedicated equipment is required for bacterial culture. Moreover, it is not preferable to use bacteria as drinking water.
  • the present invention provides a method and an apparatus for removing arsenic by easily oxidizing trivalent arsenite ions in a solution to pentavalent arsenate ions efficiently and simply. Objective.
  • Hypochlorite is used to sterilize drinking water. It has been found that by mixing this hypochlorite with a liquid containing arsenic, trivalent arsenic-containing ions can be easily oxidized to pentavalent arsenic-containing ions, and the present invention has been conceived.
  • hypochlorite When mixed with hypochlorite, the pH of the solution increases.
  • the bactericidal power of hypochlorous acid solution varies depending on its pH.
  • the inventors have found that by using a weakly acidic ion exchanger, it can be easily lowered to a weakly acidic pH preferable for an arsenic adsorbent and can be adjusted to a pH having a strong bactericidal power, and the present invention has been conceived. .
  • the present invention is a method for removing arsenic from a liquid containing arsenic, Mixing liquid and hypochlorite; Contacting the mixed solution with a weakly acidic ion exchanger to lower the pH of the solution; contacting the reduced pH solution with an arsenic adsorbent to remove arsenic from the liquid;
  • a method comprising:
  • the present invention also provides a method in which the arsenic adsorbent is a liquid activated alumina.
  • the present invention is an apparatus for removing arsenic from a solution containing arsenic, A container containing a weakly acidic ion exchanger for passing a liquid and hypochlorite mixed solution; A removal container containing an arsenic remover for removing arsenic from the liquid; An apparatus is provided.
  • the present invention is an apparatus for removing arsenic from a solution, and a pH lowering container containing a weakly acidic ion exchanger for lowering the pH of a solution in which a liquid and a hypochlorite are mixed, A removal container containing an arsenic remover for removing arsenic from the liquid; An apparatus is provided.
  • arsenic can be removed easily and quickly without using an acid such as hydrochloric acid.
  • the pH of the liquid can be adjusted easily and quickly, and arsenic can be removed easily and rapidly.
  • the pH of a solution containing hypochlorite can be adjusted from basic to weakly acidic, weakly acidic hypochlorous acid can be generated in the solution. Therefore, according to the present invention, arsenic can be removed from a liquid by a simple and quick method without using complicated equipment, and drinking water having a bactericidal effect containing weakly acidic hypochlorous acid is obtained. It is possible.
  • the method for removing arsenic from a liquid containing arsenic includes a step of mixing a liquid and hypochlorite, a step of bringing the mixed solution into contact with a weakly acidic ion exchanger to lower the pH of the solution, contacting the lowered pH solution with an arsenic adsorbent to remove arsenic from the liquid.
  • removing arsenic from the liquid means removing and reducing arsenic contained in the liquid by any means.
  • arsenic includes any compound containing an arsenic element and a salt thereof, and these ions in a liquid.
  • arsenic includes trivalent arsenite ions and pentavalent arsenate ions.
  • the trivalent arsenic-containing ions include 0 or ⁇ 1 arsenite ions such as H 3 AsO 3 0 , H 2 AsO 3 ⁇ and HAsO 3 2 ⁇ , and also include complex ion forms.
  • the pentavalent arsenic-containing ions include 0, ⁇ 1 or ⁇ 2 arsenic ions such as H 2 AsO 4 ⁇ , HAsO 4 2 ⁇ and AsO 4 3 ⁇ , and also include complex ion forms.
  • the liquid containing arsenic can be for beverages such as groundwater, river water and lake water.
  • the liquid containing arsenic can also be factory wastewater or soil contaminated water containing arsenic.
  • the liquid from which arsenic has been removed by the method of the present invention is only required to have a lower arsenic content than before removal, and does not necessarily meet the water quality standards stipulated by law as drinking water. Good.
  • the method of the present invention includes the step of mixing the liquid and the hypochlorite.
  • Hypochlorite is commonly recognized by those skilled in the art, such as sodium hypochlorite (NaClO), potassium hypochlorite (KClO), and calcium hypochlorite (Ca (ClO) 2 ). Includes any hypochlorous acid salt.
  • Hypochlorite can be mixed in the state of a solution.
  • hypochlorite commercially available materials and materials produced by methods well known to those skilled in the art can be used.
  • the solution can also be in any solution such as water.
  • sodium hypochlorite aqueous solution can be used for hypochlorite.
  • a hypochlorite solution can be prepared by adding solids such as calcium hypochlorite to water.
  • hypochlorite solution a solution having an arbitrary concentration can be used.
  • a solution having an arbitrary concentration can be used.
  • weakly acidic hypochlorous acid having a concentration that cannot be produced by a conventional method such as 10000 ppm can be produced.
  • the hypochlorite solution exists in the solution as one of hypochlorous acid, chlorine molecules, and hypochlorite ions depending on the pH.
  • an aqueous sodium hypochlorite solution is produced as an alkaline solution.
  • the aqueous sodium hypochlorite solution is diluted to 50 to 100 ppm, which is a concentration generally used as sterilizing water, the pH drops to about 8.5 to 9.5.
  • hypochlorous acid HClO and hypochlorite ion HClO ⁇ have an oxidizing action, and trivalent arsenic-containing ions in the liquid are oxidized to pentavalent arsenic-containing ions.
  • the method of the present invention includes a step of bringing the solution mixed with the hypochlorite into contact with a weakly acidic ion exchanger to lower the pH of the solution.
  • the method of the present invention uses a weakly acidic ion exchanger capable of ion exchange of a solution having a pH of 4 to 7 or more.
  • the weakly acidic ion exchanger can be, for example, an ion exchanger having a carboxylic acid group (—COOH) as an exchange group.
  • weakly acidic ion exchangers can exchange bases such as NaOH and salts of weak acids such as NaHCO 3 .
  • any weakly acidic ion exchanger known to those skilled in the art can be used as the weakly acidic ion exchanger.
  • the weak acid ion exchanger can be a weak acid ion exchange resin such as a methacrylic acid weak acid cation exchange resin and an acrylic acid weak acid cation exchange resin.
  • a weakly acidic ion exchange resin known to those skilled in the art, such as Amberlite IRC-76 (organo Corporation) and acrylic Diaion (registered trademark) WK40L (Mitsubishi Chemical Corporation).
  • Amberlite IRC-76 organic Corporation
  • acrylic Diaion (registered trademark) WK40L Mitsubishi Chemical Corporation
  • any material having an ion exchange action and a pH buffer action such as ceramic and natural ore can be used as the weak acid ion exchanger.
  • the weakly acidic ion exchanger used in the present invention has a buffering action, for example, in a weakly acidic to neutral range, in a pH range of about 3.5 to 7.5, particularly in a range of 4.0 to 7.0. Therefore, according to the method of the present invention, the pH of the solution after the treatment with the weakly acidic ion exchanger is in the range of pH 3.5 to 7.5, for example, pH 4.0 to 6.5.
  • the weakly acidic ion exchanger can be used in an arbitrary amount.
  • a person skilled in the art will be able to adjust the amount of the weakly acidic ion exchanger depending on the concentration and amount of arsenic contained in the liquid.
  • the method of the present invention does not make the pH of the liquid after passing too low even if an excessive amount of weakly acidic ion exchanger is used. Therefore, the method of the present invention can use an excess amount without adjusting the amount of the weakly acidic ion exchanger according to the concentration and amount of arsenic contained in the liquid.
  • the pH can be kept constant even when an excessive amount of weakly acidic ion exchanger is used. Therefore, after the pH of the liquid is lowered in the method of the present invention, the pH does not become too low.
  • arsenic can be oxidized, particularly when removing arsenic in drinking water, while maintaining a slightly acidic pH without compromising taste.
  • the strength of adsorption of various ions by the weakly acidic cation exchange resin is generally higher in selectivity as the valence is higher, but is particularly characterized by very high selectivity for H ions.
  • a chemical such as hydrochloric acid or sulfuric acid aqueous solution.
  • it is easy to regenerate when repeatedly used, and it is possible to regenerate with a drug amount slightly higher than the theoretical chemical equivalent.
  • the contact between the liquid and the weakly acidic ion exchanger can be performed by any method.
  • the liquid can be brought into contact with a container filled with a weak acid ion exchanger.
  • liquid can be passed from one side of the column packed with the weakly acidic ion exchanger to the other.
  • the pH of the liquid can be lowered simply by passing the liquid through a container containing a weakly acidic ion exchanger.
  • the produced hypochlorous acid does not react with the ion exchanger by being separated from the ion exchanger immediately after the contact, it is possible to suppress the decomposition of the produced hypochlorous acid due to pH reduction. it can.
  • the weakly acidic ion exchanger can be filled in a liquid permeable bag such as a nonwoven fabric. Thereby, a weak acidic ion exchanger can be easily exchanged only by changing the bag in containers, such as a column.
  • HOCl and OCl - standard reduction potential of (EO) is respectively 1.48V and 0.81 V.
  • the abundance of hypochlorous acid in the solution can be increased, and thus the sterilizing power of the solution can be increased.
  • the method of the present invention includes the step of oxidizing arsenic by contacting the liquid with a weakly acidic ion exchanger and then removing the arsenic from the oxidized liquid.
  • Arsenic can be removed by any means known to those skilled in the art.
  • arsenic can be removed by adsorbing to arsenic adsorbents such as activated alumina, iron oxide-based adsorbent filter agents, manganese oxides, cerium hydroxide, other ion exchange resins and chelate resins.
  • KH series Suditomo Chemical Co., Ltd.
  • KHD-12 and KHD-12 SR activated alumina (Al 2 O 3 )
  • READ-As Nahonkaikai Co., Ltd.
  • cerium hydroxide arsenic adsorbents. can do.
  • Adsorption of arsenic on the adsorbent can be performed by any method.
  • the liquid can be brought into contact with a container filled with an adsorbent.
  • liquid can be passed from one of the columns packed with adsorbent to the other.
  • liquid arsenic whose pH is adjusted can be easily adsorbed only by passing the liquid through a container containing an adsorbent.
  • the adsorbent can be filled in a liquid permeable bag such as a nonwoven fabric. Thus, the adsorbent can be easily replaced simply by replacing the bag in the container such as a column.
  • the contact with the weak acid ion exchanger and the subsequent adsorption of arsenic to the adsorbent can be performed continuously.
  • a series of columns in which a column packed with a weakly acidic ion exchanger and a column packed with an adsorbent are connected can be used. By using the connected column, it is possible to oxidize arsenic in the liquid simply by passing through this column, and to adsorb arsenic.
  • trivalent arsenic is oxidized to pentavalent, and the pH of the solution containing arsenic is reduced to about 5 to 7, so that the pH range is suitable for an arsenic adsorbent. Therefore, according to the method of the present invention, trivalent arsenic oxidation and pH adjustment, which are problematic in an arsenic adsorbent such as activated alumina, can be easily and rapidly performed. Furthermore, since the produced hypochlorous acid solution is in a pH range where the abundance of hypochlorous acid is high, a solution having a high bactericidal effect can be produced at the same time.
  • the contact between the liquid and the weakly acidic ion exchanger and the adsorption to the adsorbent can be performed in the same container.
  • a weakly acidic ion exchanger and an adsorbent can be mixed and packed in a column.
  • arsenic in the liquid can be oxidized by simply passing through the column, and arsenic can be adsorbed.
  • An apparatus for removing arsenic from a solution of the present invention comprises a pH lowering container containing a weakly acidic ion exchanger for lowering the pH of a solution mixed with a liquid and hypochlorite, and an arsenic from the liquid. And a removal container containing an arsenic removing agent.
  • the apparatus of the present invention includes an ion exchanger-filled container such as a column packed with a weakly acidic ion exchanger as a pH lowering container.
  • the weakly acidic ion exchanger can use the materials as described above.
  • the hypochlorite solution that has passed through the ion exchanger filled container can react with the weakly acidic ion exchanger to lower the pH of the liquid.
  • the pH lowering container is connected to a removing container containing an arsenic removing agent.
  • an arsenic removing agent the material as described above can be used.
  • Arsenic can be removed by the liquid having a lowered pH coming into contact with the arsenic removing agent in the removal container.
  • the apparatus of the present invention is used as follows, for example.
  • hypochlorite as described above is added to the solution.
  • hypochlorite as described above is added to the solution.
  • a pH lowering container When drinking water is produced by removing arsenic from a 100 ml solution, several drops to tens of ppm sodium hypochlorite solution can be obtained by adding a few drops of 10000 ppm sodium hypochlorite solution to the solution. Become.
  • This solution is introduced into a pH lowering container.
  • the pH of the introduced hypochlorite solution is lowered to pH 5-7, which is a pH suitable for adsorption of the arsenic removing agent.
  • the solution is introduced into the removal container.
  • arsenic is adsorbed by the arsenic adsorbent, and a solution from which arsenic has been removed is generated.
  • the apparatus of the present invention may further include a storage container.
  • a liquid and hypochlorite are mixed in a storage container.
  • the hypochlorite solution is connected to an ion exchanger filled container filled with a weakly acidic ion exchanger, and the solution is introduced from the storage container into the ion exchanger filled container.
  • the storage container may further include a pump for introducing the solution into the ion exchanger filling container, and may be connected to the ion exchanger filling container via the pump.
  • the ion exchanger and the arsenic removing agent can be mixed and used. In this case, it is not necessary to separate the pH lowering container and the removing container from each other, and it is sufficient to fill the single container with the mixture of the ion exchanger and the arsenic removing agent. By passing the liquid through the mixture, arsenic in the liquid can be oxidized and adsorbed by simply passing through the column.
  • Example 1 Materials and Methods In Example 1, as a liquid, reagent arsenic was added to distilled water to prepare raw water so as to have an arsenic concentration of 0.5 ppm. *
  • arsenic standard solution 1000 ppm (Merck Millipore) was added to distilled water and diluted to 0.25 ppm.
  • 6500 ppm of sodium arsenite aqueous solution (Merck Millipore) was added to distilled water to make 0.25 ppm.
  • raw water containing a total of 0.5 ppm arsenic standard solution + sodium arsenite aqueous solution was prepared.
  • Example 4 groundwater collected in Sri Lanka was used as raw water. These groundwaters are known to contain trivalent and pentavalent arsenic. The groundwater contained 0.03 ppm arsenic. *
  • Acrylic Diaion (registered trademark) WK40L (Mitsubishi Chemical Corporation) was used as the weakly acidic ion exchanger.
  • READ-As (Nihonkaikai Co., Ltd.) was used as an arsenic adsorbent.
  • Commercial activated alumina was used as the activated alumina. *
  • the arsenic content was measured using the Emquant TM Arsenic Test (Merck Millipore) and the Arsenic Mercoquant Arsenic Test (Ultra Sensitive Type) (Merck Millipore).
  • the pH was measured using a pH portable water quality meter P-30 (Toa DKK).
  • a handy water quality meter “AQUAB” AQ-202 type was used. *
  • Example 1 Confirmation of Arsenic Removal Effect by the Method of the Present Invention
  • arsenic removal from raw water prepared by adding reagent arsenic to distilled water to a concentration of 0.5 ppm was confirmed.
  • a column packed with 2 ml of arsenic adsorbent + 20 ml of weak acid ion exchanger, 2 ml of activated alumina + 20 ml of weak acid ion exchanger were prepared.
  • a column only packed with 20 ml of weakly acidic ion exchanger was also produced. *
  • the arsenic content of the raw water was measured and found to be 0.5 ppm.
  • the arsenic content of the liquid obtained by passing raw water through a column packed with 20 ml of weakly acidic ion exchanger + 2 ml of arsenic adsorbent was measured, it was 0.05 ppm. It can be seen that treating the arsenic solution with a weakly acidic ion exchanger lowers the pH and increases the effect of arsenic adsorption. Arsenic could be removed very efficiently by the arsenic removal method of the present invention. *
  • Example 2 Confirmation of removal effect of arsenous acid and arsenic by activated alumina by the method of the present invention
  • reagent arsenic acid and arsenic were added to distilled water, and each of them was 0.25 ppm (total of 0.5 ppm). The removal of arsenic from the raw water mixed to include the concentration was confirmed. *
  • Example 3 Confirmation of removal effect of arsenous acid and arsenic by activated alumina and hypochlorous acid by the method of the present invention
  • reagent arsenic acid and arsenic were added to distilled water, and each was 0.25 ppm ( The removal of arsenic from the raw water mixed so as to include a concentration of 0.5 ppm in total was confirmed. Further, sodium hypochlorite was added to the raw water containing this arsenic so as to have a final concentration of 50 ppm.
  • Example 4 Confirmation of Arsenic Removal Effect from Vietnamese Water Containing Arsenic
  • groundwater collected in Sri Lanka was used as raw water.
  • a column packed with 2 ml of arsenic adsorbent + 20 ml of weak acid ion exchanger, 2 ml of activated alumina + 20 ml of weak acid ion exchanger were prepared.
  • a column only packed with 20 ml of weakly acidic ion exchanger was also produced.
  • each of raw water and raw water treated by the method of the present invention was seeded on an agar plate and cultured at 37 ° C. for 22 hours. Bacteria did not grow at all in the raw water treated by the method of the present invention, but bacteria grew in the untreated raw water.
  • arsenic can be easily and quickly removed from raw water, and a weakly acidic hypochlorous acid solution can be generated. Therefore, it can be used as a useful water purifier.

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Abstract

[Problem] The purpose of the invention is to provide a method and a device for removing arsenic in an efficient, simple, and speedy manner. [Solution] The inventors of the present invention conceived of the present invention upon discovering that mixing a hypochlorite with a liquid containing arsenic makes it possible to easily cause trivalent arsenic-containing ions to oxidize into pentavalent arsenic-containing ions. The inventors conceived of the present invention upon discovering that using a weakly acidic ion exchanger makes it possible to easily reduce the pH to a weakly acidic level suitable for an arsenic adsorbent and to adjust the pH to that at which a high sterilizing power is obtained. The present invention provides a method including: a step for mixing the liquid and the hypochlorite; a step for bringing the mixture solution into contact with a weakly acidic ion exchanger and reducing the pH of the solution; and a step for bringing the solution for which the pH has been reduced into contact with an arsenic adsorbent and removing arsenic from the liquid.

Description

ヒ素を除去するための方法および装置Method and apparatus for removing arsenic
　本発明は、地下水などの液体からヒ素を除去するための方法および装置に関する。 The present invention relates to a method and apparatus for removing arsenic from a liquid such as groundwater.
　地球上には、適切な浄水施設や下水処理施設がなく、また水不足によって、安全な飲料水を確保することが難しい地域が多く存在する。このような地域では、多くの子供たちが不衛生な水を飲むことによって病気にかかったり、命を落としたりしている。 地球 There are many areas on the earth where there are no appropriate water purification facilities and sewage treatment facilities, and it is difficult to secure safe drinking water due to water shortages. In these areas, many children get sick or die by drinking unsanitary water.
　また、水に含まれるヒ素、鉄、マンガンおよびアンモニウムイオンなどの様々な有害物質が問題になっている。たとえばバングラデシュなどでは、基準値を超える濃度のヒ素を含む井戸水を毎日飲み続けている人々が多く存在する。ヒ素を含む水を飲み続けると、皮膚の色素沈着、角化症、胃腸炎、肝障害および心臓血管系循環障害などを発症するおそれがあるといわれている。 In addition, various harmful substances such as arsenic, iron, manganese and ammonium ions contained in water have become a problem. In Bangladesh, for example, there are many people who continue to drink well water containing arsenic in concentrations exceeding the standard value every day. Continuing to drink water containing arsenic is said to cause skin pigmentation, keratosis, gastroenteritis, liver damage and cardiovascular circulatory disturbance.
　地下水中のおもな形態は、無機態であるヒ酸（H3AsO4）および亜ヒ酸（H3AsO3）であり、イオン形態で存在している。地下水は、還元的環境下にあることにより、地下水中のヒ素は酸化数3の亜ヒ酸イオンの形態で存在している場合が多い。亜ヒ酸塩は、ヒ酸塩に比べ溶解性が高く、吸着材への吸着性も劣ることが公知である。たとえば、ヒ素除去剤として、活性アルミナ（Al2O3）、水酸化鉄などの鉄系化合物および酸化セリウムなどが知られているが、この場合も亜ヒ酸イオンが活性アルミナなどにほとんど吸着されないことが問題となっている。このため、水からヒ素を除去するためには、ヒ素を酸化する技術も重要となる。また、活性アルミナ（Al2O3）、鉄系化合物および酸化セリウムなどの吸着剤は、弱酸性～中性のpHにおいて吸着率が高いことが知られている。 The main forms of groundwater are arsenic acid (H 3 AsO 4 ) and arsenous acid (H 3 AsO 3 ), which are inorganic, and exist in an ionic form. Since groundwater is in a reducing environment, arsenic in groundwater often exists in the form of arsenite ions with an oxidation number of 3. It is known that arsenite has higher solubility than arsenate and inferior adsorbability to the adsorbent. For example, activated alumina (Al 2 O 3 ), iron-based compounds such as iron hydroxide, and cerium oxide are known as arsenic removal agents, but in this case as well, arsenite ions are hardly adsorbed on activated alumina. Is a problem. For this reason, in order to remove arsenic from water, a technique for oxidizing arsenic is also important. Further, it is known that adsorbents such as activated alumina (Al 2 O 3 ), iron-based compounds and cerium oxide have a high adsorption rate at a weakly acidic to neutral pH.
　一方、ヒ素を含有する水を飲用とする場合などは、水の殺菌も問題となる。そこで、ヒ素を除去する際に殺菌も行うことができれば、より迅速かつ容易に飲料水を生成することができる。 On the other hand, when drinking water containing arsenic, water sterilization is also a problem. Therefore, if sterilization can be performed when removing arsenic, drinking water can be generated more quickly and easily.
　特許文献1には、亜ヒ酸酸化細菌によってヒ素を酸化することが記載されている。しかし、細菌の培養のためには、専用の設備が必要となる。また、細菌を使用することは、飲料水として好ましくない。 Patent Document 1 describes that arsenic is oxidized by arsenite oxidizing bacteria. However, dedicated equipment is required for bacterial culture. Moreover, it is not preferable to use bacteria as drinking water.
特開2012-210577号公報JP 2012-210577
　上述したように、複雑な設備を用いることなく、簡易かつ迅速な方法で液体からヒ素を除去して、安全な飲料水を得るためのさらなる技術が求められている。 As described above, there is a need for further technology for obtaining safe drinking water by removing arsenic from a liquid by a simple and quick method without using complicated equipment.
　そこで、本発明は、効率よく、簡易かつ迅速に溶液中の3価の亜ヒ酸イオンを5価のヒ酸イオンに容易に酸化してヒ素を除去するための方法および装置を提供することを目的とする。 Therefore, the present invention provides a method and an apparatus for removing arsenic by easily oxidizing trivalent arsenite ions in a solution to pentavalent arsenate ions efficiently and simply. Objective.
　飲料水の殺菌には、次亜塩素酸塩が使用される。この次亜塩素酸塩をヒ素を含有する液体と混合することにより、容易に3価ヒ素含有イオンを5価ヒ素含有イオンに酸化することができることを見出し、本発明に想到した。次亜塩素酸塩と混合すると、溶液のpHが上昇してしまう。一方、次亜塩素酸溶液の殺菌力は、そのpHに応じて変動する。そこで、弱酸性イオン交換体を使用することにより、ヒ素吸着剤のために好ましい弱酸性のpHに容易に低下させることができ、かつ殺菌力の強いpHに調整できることを見出し、本発明に想到した。 Hypochlorite is used to sterilize drinking water. It has been found that by mixing this hypochlorite with a liquid containing arsenic, trivalent arsenic-containing ions can be easily oxidized to pentavalent arsenic-containing ions, and the present invention has been conceived. When mixed with hypochlorite, the pH of the solution increases. On the other hand, the bactericidal power of hypochlorous acid solution varies depending on its pH. Thus, the inventors have found that by using a weakly acidic ion exchanger, it can be easily lowered to a weakly acidic pH preferable for an arsenic adsorbent and can be adjusted to a pH having a strong bactericidal power, and the present invention has been conceived. .
　本発明は、ヒ素を含有する液体からヒ素を除去する方法であって、
　液体と次亜塩素酸塩を混合する工程と、
　混合溶液を弱酸性イオン交換体と接触させて、溶液のpHを低下させる工程と、
　pHが低下した溶液をヒ素吸着剤と接触させて、液体からヒ素を除去する工程と、
を含む方法を提供する。 The present invention is a method for removing arsenic from a liquid containing arsenic,
Mixing liquid and hypochlorite;
Contacting the mixed solution with a weakly acidic ion exchanger to lower the pH of the solution;
contacting the reduced pH solution with an arsenic adsorbent to remove arsenic from the liquid;
A method comprising:
　また、本発明は、上記ヒ素吸着剤が液体を活性アルミナである方法を提供する。 The present invention also provides a method in which the arsenic adsorbent is a liquid activated alumina.
　さらに、本発明は、ヒ素を含有する溶液からヒ素を除去する装置であって、
　液体と次亜塩素酸塩を混合した溶液を通過させるための、弱酸性イオン交換体を含む容器と、
　液体からヒ素を除去するための、ヒ素除去剤を含む除去用容器と、
を備える装置を提供する。 Furthermore, the present invention is an apparatus for removing arsenic from a solution containing arsenic,
A container containing a weakly acidic ion exchanger for passing a liquid and hypochlorite mixed solution;
A removal container containing an arsenic remover for removing arsenic from the liquid;
An apparatus is provided.
　また、本発明は、溶液からヒ素を除去する装置であって、液体と次亜塩素酸塩を混合した溶液のpHを低下させるための、弱酸性イオン交換体を含むpH低下容器と、
　液体からヒ素を除去するための、ヒ素除去剤を含む除去用容器と、
を備える装置を提供する。 Further, the present invention is an apparatus for removing arsenic from a solution, and a pH lowering container containing a weakly acidic ion exchanger for lowering the pH of a solution in which a liquid and a hypochlorite are mixed,
A removal container containing an arsenic remover for removing arsenic from the liquid;
An apparatus is provided.
　本発明によれば、塩酸などの酸を使用することなく、簡易かつ迅速にヒ素を除去することができる。また、本発明によれば、簡易かつ迅速に液体のpHを調整することができ、簡易かつ迅速にヒ素を除去することができる。さらに、本発明によれば、次亜塩素酸塩を含む溶液のpHを塩基性から弱酸性に調整することができるため、溶液中には弱酸性次亜塩素酸を生成させることができる。したがって、本発明によれば、複雑な設備を用いることなく、簡易かつ迅速な方法で液体からヒ素を除去することができると共に、弱酸性次亜塩素酸を含有する殺菌効果を有する飲料水を得ることが可能である。 According to the present invention, arsenic can be removed easily and quickly without using an acid such as hydrochloric acid. Further, according to the present invention, the pH of the liquid can be adjusted easily and quickly, and arsenic can be removed easily and rapidly. Furthermore, according to the present invention, since the pH of a solution containing hypochlorite can be adjusted from basic to weakly acidic, weakly acidic hypochlorous acid can be generated in the solution. Therefore, according to the present invention, arsenic can be removed from a liquid by a simple and quick method without using complicated equipment, and drinking water having a bactericidal effect containing weakly acidic hypochlorous acid is obtained. It is possible.
本発明のヒ素を除去する方法の手順を示す図。The figure which shows the procedure of the method of removing arsenic of this invention.
　本発明のヒ素を含有する液体からヒ素を除去する方法は、液体と次亜塩素酸塩を混合する工程と、混合溶液を弱酸性イオン交換体と接触させて溶液のpHを低下させる工程と、pHが低下した溶液をヒ素吸着剤と接触させて液体からヒ素を除去する工程とを含む。 The method for removing arsenic from a liquid containing arsenic according to the present invention includes a step of mixing a liquid and hypochlorite, a step of bringing the mixed solution into contact with a weakly acidic ion exchanger to lower the pH of the solution, contacting the lowered pH solution with an arsenic adsorbent to remove arsenic from the liquid.
　本明細書において、「液体からヒ素を除去する」は、液体に含まれるヒ素を任意の手段によって取り除くこと、および減少させることをいう。 In the present specification, “removing arsenic from the liquid” means removing and reducing arsenic contained in the liquid by any means.
　また、本明細書において、「ヒ素」とは、ヒ素元素を含有する任意の化合物およびその塩、並びに液体中のこれらのイオンを含む。特に、「ヒ素」は、3価の亜ヒ酸イオンおよび5価のヒ酸イオンを含む。3価のヒ素含有イオンには、H3AsO3 0、H2AsO3 -およびHAsO3 2-などの0または-1価の亜ヒ酸系イオンを含み、錯体イオンの形態も含む。5価のヒ素含有イオンには、H2AsO4 -、HAsO4 2-およびAsO4 3-などの0、-1または-2価のヒ酸系イオンを含み、錯体イオンの形態も含む。 In the present specification, “arsenic” includes any compound containing an arsenic element and a salt thereof, and these ions in a liquid. In particular, “arsenic” includes trivalent arsenite ions and pentavalent arsenate ions. The trivalent arsenic-containing ions include 0 or −1 arsenite ions such as H 3 AsO 3 0 , H 2 AsO 3 − and HAsO 3 2−, and also include complex ion forms. The pentavalent arsenic-containing ions include 0, −1 or −2 arsenic ions such as H 2 AsO 4 − , HAsO 4 2− and AsO 4 3−, and also include complex ion forms.
　ヒ素を含有する液体は、地下水、河川水および湖沼水などの飲料用のものであることができる。また、ヒ素を含有する液体は、工場排水やヒ素を含む土壌の汚染水などであることもできる。なお、本発明の方法によってヒ素が除去された液体は、除去前よりもヒ素の含有量が減少されていればよく、必ずしも飲用水等として法律で定められた水質基準を満たすものでなくてもよい。 The liquid containing arsenic can be for beverages such as groundwater, river water and lake water. The liquid containing arsenic can also be factory wastewater or soil contaminated water containing arsenic. The liquid from which arsenic has been removed by the method of the present invention is only required to have a lower arsenic content than before removal, and does not necessarily meet the water quality standards stipulated by law as drinking water. Good.
　本発明の方法は、液体と次亜塩素酸塩を混合する工程を含む。次亜塩素酸塩は、当業者に一般的に認識されるとおり、次亜塩素酸ナトリウム（NaClO）、次亜塩素酸カリウム（KClO）および次亜塩素酸カルシウム（Ca(ClO)２）などの任意の次亜塩素酸の塩を含む。また、次亜塩素酸塩は、溶液の状態で混合することができる。次亜塩素酸塩は、市販の材料および当業者に周知の方法によって製造された材料を使用することができる。また、溶液は、水などの任意の溶液中のものであることができる。具体的には、次亜塩素酸塩は、次亜塩素酸ナトリウム水溶液を使用することができる。また、次亜塩素酸カルシウムなどの固体を水に添加することにより、次亜塩素酸塩溶液を調製することができる。 The method of the present invention includes the step of mixing the liquid and the hypochlorite. Hypochlorite is commonly recognized by those skilled in the art, such as sodium hypochlorite (NaClO), potassium hypochlorite (KClO), and calcium hypochlorite (Ca (ClO) 2 ). Includes any hypochlorous acid salt. Hypochlorite can be mixed in the state of a solution. As hypochlorite, commercially available materials and materials produced by methods well known to those skilled in the art can be used. The solution can also be in any solution such as water. Specifically, sodium hypochlorite aqueous solution can be used for hypochlorite. Moreover, a hypochlorite solution can be prepared by adding solids such as calcium hypochlorite to water.
　本発明の方法において、次亜塩素酸塩溶液は、任意の濃度の溶液を使用することができる。たとえば、100mlの溶液からヒ素を除去して飲用水を生成する場合、溶液に10000ppmの次亜塩素酸ナトリウム溶液を数滴添加することにより、数ppm～数十ppmの次亜塩素酸ナトリウム溶液となる。また、市販されている12％次亜塩素酸ナトリウム溶液を希釈して、1～120000ppm以上の濃度、たとえば1、5、10、50、100、200、500、1000、10000および120000ppmで使用することができる。本発明の方法によれば、10000ppmといった従来の方法では製造することができない濃度の弱酸性次亜塩素酸を製造することができる。 In the method of the present invention, as the hypochlorite solution, a solution having an arbitrary concentration can be used. For example, when drinking water is produced by removing arsenic from a 100 ml solution, several drops to tens of ppm sodium hypochlorite solution can be obtained by adding a few drops of 10000 ppm sodium hypochlorite solution to the solution. Become. In addition, dilute a commercially available 12% sodium hypochlorite solution and use it at a concentration of 1 to 120,000 ppm or more, for example, 1, 5, 10, 50, 100, 200, 500, 1000, 10000 and 120,000 ppm. Can do. According to the method of the present invention, weakly acidic hypochlorous acid having a concentration that cannot be produced by a conventional method such as 10000 ppm can be produced.
　次亜塩素酸塩溶液は、溶液中において、そのpHに応じて次亜塩素酸、塩素分子および次亜塩素酸イオンのいずれかとして存在している。一般に次亜塩素酸ナトリウム水溶液は、アルカリ性の溶液として製造される。次亜塩素酸ナトリウム水溶液は、一般的に殺菌水とて使用される濃度である50～100ppmまで希釈すると、pHは、8.5～9.5程度まで低下する。このpHでも次亜塩素酸ナトリウム溶液は、次亜塩素酸HClOおよび次亜塩素酸イオンHClO-が酸化作用を有し、液体中の3価ヒ素含有イオンを5価ヒ素含有イオンに酸化される。 The hypochlorite solution exists in the solution as one of hypochlorous acid, chlorine molecules, and hypochlorite ions depending on the pH. In general, an aqueous sodium hypochlorite solution is produced as an alkaline solution. When the aqueous sodium hypochlorite solution is diluted to 50 to 100 ppm, which is a concentration generally used as sterilizing water, the pH drops to about 8.5 to 9.5. Even at this pH, in the sodium hypochlorite solution, hypochlorous acid HClO and hypochlorite ion HClO − have an oxidizing action, and trivalent arsenic-containing ions in the liquid are oxidized to pentavalent arsenic-containing ions.
　次いで、本発明の方法は、上記次亜塩素酸塩と混合した溶液を弱酸性イオン交換体と接触させて溶液のpHを低下させる工程を含む。 Next, the method of the present invention includes a step of bringing the solution mixed with the hypochlorite into contact with a weakly acidic ion exchanger to lower the pH of the solution.
　本発明の方法は、pH4～7以上の溶液をイオン交換することができる弱酸性イオン交換体を使用する。弱酸性イオン交換体は、たとえばカルボン酸基（-COOH）を交換基として持つイオン交換体であることができる。また、弱酸性イオン交換体は、NaOHなどの塩基およびNaHCO3のような弱酸の塩を交換することができる。本発明の方法において、弱酸性イオン交換体は、当業者に公知の任意の弱酸性イオン交換体を使用することができる。弱酸性イオン交換体は、メタクリル酸系弱酸性陽イオン交換樹脂およびアクリル酸系弱酸性陽イオン交換樹脂などの弱酸性イオン交換樹脂であることができる。たとえば、アンバーライトIRC-76（オルガノ株式会社）およびアクリル系ダイヤイオン（登録商標）WK40L（三菱化学株式会社）などの当業者に公知の弱酸性イオン交換樹脂であることができる。また、弱酸性イオン交換樹脂の他にも、セラミックおよび天然の鉱石など、イオン交換作用およびpH緩衝作用を有する任意の材料を弱酸性イオン交換体使用することができる。 The method of the present invention uses a weakly acidic ion exchanger capable of ion exchange of a solution having a pH of 4 to 7 or more. The weakly acidic ion exchanger can be, for example, an ion exchanger having a carboxylic acid group (—COOH) as an exchange group. Also, weakly acidic ion exchangers can exchange bases such as NaOH and salts of weak acids such as NaHCO 3 . In the method of the present invention, any weakly acidic ion exchanger known to those skilled in the art can be used as the weakly acidic ion exchanger. The weak acid ion exchanger can be a weak acid ion exchange resin such as a methacrylic acid weak acid cation exchange resin and an acrylic acid weak acid cation exchange resin. For example, it may be a weakly acidic ion exchange resin known to those skilled in the art, such as Amberlite IRC-76 (organo Corporation) and acrylic Diaion (registered trademark) WK40L (Mitsubishi Chemical Corporation). In addition to the weak acid ion exchange resin, any material having an ion exchange action and a pH buffer action such as ceramic and natural ore can be used as the weak acid ion exchanger.
　また、本発明に使用される弱酸性イオン交換体は、たとえば弱酸性～中性の範囲、pHが約3.5～7.5の値の範囲、特に4.0～7.0の値の範囲で緩衝作用を持つ。したがって、本発明の方法によれば、弱酸性イオン交換体で処理した後の溶液のpHは、pH3.5～7.5、たとえばpH4.0～6.5の範囲である。 In addition, the weakly acidic ion exchanger used in the present invention has a buffering action, for example, in a weakly acidic to neutral range, in a pH range of about 3.5 to 7.5, particularly in a range of 4.0 to 7.0. Therefore, according to the method of the present invention, the pH of the solution after the treatment with the weakly acidic ion exchanger is in the range of pH 3.5 to 7.5, for example, pH 4.0 to 6.5.
　また、本発明の方法において、弱酸性イオン交換体は、任意の量で使用することができる。当業者であれば、液体中に含まれるヒ素の濃度および量などに応じて、弱酸性イオン交換体の量を調節することができるであろう。しかし、本発明の方法は、過剰量の弱酸性イオン交換体を使用しても、通過後の液体のpHが低くなりすぎることはない。したがって、本発明の方法は、液体中に含まれるヒ素の濃度および量などに応じて弱酸性イオン交換体の量を調節することなく、過剰量を使用することができる。 In the method of the present invention, the weakly acidic ion exchanger can be used in an arbitrary amount. A person skilled in the art will be able to adjust the amount of the weakly acidic ion exchanger depending on the concentration and amount of arsenic contained in the liquid. However, the method of the present invention does not make the pH of the liquid after passing too low even if an excessive amount of weakly acidic ion exchanger is used. Therefore, the method of the present invention can use an excess amount without adjusting the amount of the weakly acidic ion exchanger according to the concentration and amount of arsenic contained in the liquid.
　上記のとおり、本発明の方法では、過剰量の弱酸性イオン交換体を使用してもpHを一定に維持することができる。したがって、本発明の方法において液体のpHを低下させた後に、pHが低くなりすぎることはない。したがって、特に飲料水のヒ素を除去する際に、ヒ素を酸化することができる一方、味覚を損なうことなく弱酸性のpHに維持することができる。 As described above, in the method of the present invention, the pH can be kept constant even when an excessive amount of weakly acidic ion exchanger is used. Therefore, after the pH of the liquid is lowered in the method of the present invention, the pH does not become too low. Thus, arsenic can be oxidized, particularly when removing arsenic in drinking water, while maintaining a slightly acidic pH without compromising taste.
　一方、弱酸性陽イオン交換樹脂の各種イオンに対する吸着の強さは、一般に価数が高いイオン程選択性が大きくなるが、特にHイオンに対する選択性が非常に大きいのが特徴である。このため、Hイオンが他の陽イオンで交換された後、塩酸または硫酸水溶液などの薬剤を使用して容易にR-COOHの形に戻すことができる。このため、繰り返し使用する時の再生が容易であり、理論化学当量より僅かに多い程度の薬剤量で再生が可能となる。 On the other hand, the strength of adsorption of various ions by the weakly acidic cation exchange resin is generally higher in selectivity as the valence is higher, but is particularly characterized by very high selectivity for H ions. For this reason, after the H ions are exchanged with other cations, they can be easily returned to the R-COOH form using a chemical such as hydrochloric acid or sulfuric acid aqueous solution. For this reason, it is easy to regenerate when repeatedly used, and it is possible to regenerate with a drug amount slightly higher than the theoretical chemical equivalent.
　本発明の方法において、液体と弱酸性イオン交換体との接触は、任意の方法で行うことができる。たとえば、弱酸性イオン交換体が充填された容器に、液体を通過させることによって接触させことができる。たとえば、弱酸性イオン交換体が充填されたカラムの一方から他方へ液体を通過させることができる。本発明の方法によれば、弱酸性イオン交換体を含む容器に液体を通過させるだけで、液体のpHを低下させることができる。また、接触後、直ちにイオン交換体から分離されることにより、生成した次亜塩素酸がイオン交換体と反応することがないため、pH低下によって生成した次亜塩素酸の分解を抑制することができる。 In the method of the present invention, the contact between the liquid and the weakly acidic ion exchanger can be performed by any method. For example, the liquid can be brought into contact with a container filled with a weak acid ion exchanger. For example, liquid can be passed from one side of the column packed with the weakly acidic ion exchanger to the other. According to the method of the present invention, the pH of the liquid can be lowered simply by passing the liquid through a container containing a weakly acidic ion exchanger. Moreover, since the produced hypochlorous acid does not react with the ion exchanger by being separated from the ion exchanger immediately after the contact, it is possible to suppress the decomposition of the produced hypochlorous acid due to pH reduction. it can.
　また、弱酸性イオン交換体は、不織布などの液体透過性の袋に充填しておくことができる。これにより、カラムなどの容器内の袋を入れ替えるだけで、容易に弱酸性イオン交換体を交換することができる。 The weakly acidic ion exchanger can be filled in a liquid permeable bag such as a nonwoven fabric. Thereby, a weak acidic ion exchanger can be easily exchanged only by changing the bag in containers, such as a column.
　上記のように、ヒ素を含有する溶液のpHを弱酸性に低下させることにより、より協力に液体中の3価ヒ素含有イオンを5価ヒ素含有イオンに酸化される。HOClとOCl-の標準還元電位(EO)は、それぞれ1.48Vと0.81Vある。 As described above, by reducing the pH of the arsenic-containing solution to weak acidity, the trivalent arsenic-containing ions in the liquid are more cooperatively oxidized to pentavalent arsenic-containing ions. HOCl and OCl - standard reduction potential of (EO) is respectively 1.48V and 0.81 V.
　また、上記のように、溶液のpHを弱酸性に低下させることにより、溶液における次亜塩素酸の存在率を高めることができ、したがって溶液の殺菌力を高めることができる。 Also, as described above, by reducing the pH of the solution to weak acidity, the abundance of hypochlorous acid in the solution can be increased, and thus the sterilizing power of the solution can be increased.
　本発明の方法は、液体と弱酸性イオン交換体との接触によってヒ素を酸化した後、酸化された液体からヒ素を除去する工程を含む。ヒ素の除去は、当業者に公知の任意の手段を使用することができる。たとえば、ヒ素は、活性アルミナ、鉄酸化物系の吸着濾過剤、マンガン酸化物、水酸化セリウム、その他のイオン交換樹脂およびキレート樹脂などのヒ素吸着剤に吸着させることによって除去することができる。たとえば、活性アルミナ（Al2O3）としてKHD-12およびKHD-12 SRなどのKHシリーズ（住友化学株式会社）および水酸化セリウムとしてREAD-As(株式会社日本海水)などをヒ素吸着剤として使用することができる。 The method of the present invention includes the step of oxidizing arsenic by contacting the liquid with a weakly acidic ion exchanger and then removing the arsenic from the oxidized liquid. Arsenic can be removed by any means known to those skilled in the art. For example, arsenic can be removed by adsorbing to arsenic adsorbents such as activated alumina, iron oxide-based adsorbent filter agents, manganese oxides, cerium hydroxide, other ion exchange resins and chelate resins. For example, KH series (Sumitomo Chemical Co., Ltd.) such as KHD-12 and KHD-12 SR as activated alumina (Al 2 O 3 ) and READ-As (Nihonkaikai Co., Ltd.) as cerium hydroxide are used as arsenic adsorbents. can do.
　吸着剤へのヒ素の吸着は、任意の方法で行うことができる。たとえば、吸着剤が充填された容器に、液体を通過させることによって接触させことができる。たとえば、吸着剤が充填されたカラムの一方から他方へ液体を通過させることができる。本発明の方法によれば、吸着剤を含む容器に液体を通過させるだけで、pH調整された液体のヒ素を容易に吸着することができる。また、吸着剤は、不織布などの液体透過性の袋に充填しておくことができる。これにより、カラムなどの容器内の袋を入れ替えるだけで、容易に吸着剤を交換することができる。 Adsorption of arsenic on the adsorbent can be performed by any method. For example, the liquid can be brought into contact with a container filled with an adsorbent. For example, liquid can be passed from one of the columns packed with adsorbent to the other. According to the method of the present invention, liquid arsenic whose pH is adjusted can be easily adsorbed only by passing the liquid through a container containing an adsorbent. The adsorbent can be filled in a liquid permeable bag such as a nonwoven fabric. Thus, the adsorbent can be easily replaced simply by replacing the bag in the container such as a column.
　また、一つの態様において、上記の弱酸性イオン交換体との接触およびその後の吸着剤へのヒ素の吸着は、連続して行うことができる。たとえば、弱酸性イオン交換体が充填されたカラムと吸着剤が充填されたカラムを接続された一連のカラムを使用することができる。接続されたカラムを使用することにより、このカラムを通過させるだけで液体中のヒ素を酸化させることができ、ヒ素を吸着することができる。 Also, in one embodiment, the contact with the weak acid ion exchanger and the subsequent adsorption of arsenic to the adsorbent can be performed continuously. For example, a series of columns in which a column packed with a weakly acidic ion exchanger and a column packed with an adsorbent are connected can be used. By using the connected column, it is possible to oxidize arsenic in the liquid simply by passing through this column, and to adsorb arsenic.
　特に、本発明の方法では、3価のヒ素が5価に酸化されていると共に、ヒ素を含む溶液のpHが約5～7程度に低下され、ヒ素吸着剤に適したpH範囲となる。したがって、本発明の方法は、活性アルミナなどのヒ素吸着剤において問題とされている3価ヒ素の酸化およびpHの調節を簡便かつ迅速に行うことができる。さらに、生成した次亜塩素酸溶液は、次亜塩素酸の存在率が高いpH範囲となるため、同時に殺菌効果の高い溶液を生成することができる。 In particular, in the method of the present invention, trivalent arsenic is oxidized to pentavalent, and the pH of the solution containing arsenic is reduced to about 5 to 7, so that the pH range is suitable for an arsenic adsorbent. Therefore, according to the method of the present invention, trivalent arsenic oxidation and pH adjustment, which are problematic in an arsenic adsorbent such as activated alumina, can be easily and rapidly performed. Furthermore, since the produced hypochlorous acid solution is in a pH range where the abundance of hypochlorous acid is high, a solution having a high bactericidal effect can be produced at the same time.
　また、一つの態様において、液体と弱酸性イオン交換体との接触および吸着剤への吸着は、同一の容器内で行うこともできる。たとえば、弱酸性イオン交換体と吸着剤を混合してカラムに充填することができる。この混合物のカラムに液体を通過させることにより、カラムを通過させるだけで液体中のヒ素を酸化させることができ、ヒ素を吸着することができる。また、弱酸性イオン交換体と吸着剤との混合物を充填することにより、カラムを別々に準備する必要がなくなる。したがって、より簡易に本発明の方法を実施することができる。 In one embodiment, the contact between the liquid and the weakly acidic ion exchanger and the adsorption to the adsorbent can be performed in the same container. For example, a weakly acidic ion exchanger and an adsorbent can be mixed and packed in a column. By passing the liquid through the column of the mixture, arsenic in the liquid can be oxidized by simply passing through the column, and arsenic can be adsorbed. Moreover, it is not necessary to prepare the columns separately by filling the mixture of the weakly acidic ion exchanger and the adsorbent. Therefore, the method of the present invention can be carried out more easily.
　次に、本発明の溶液からヒ素を除去する装置について、詳細に説明する。本発明の溶液からヒ素を除去する装置は、液体と次亜塩素酸塩を混合した溶液のpHを低下させるための、弱酸性イオン交換体を含むpH低下容器と、液体からヒ素を除去するための、ヒ素除去剤を含む除去用容器とを備える。 Next, an apparatus for removing arsenic from the solution of the present invention will be described in detail. An apparatus for removing arsenic from a solution of the present invention comprises a pH lowering container containing a weakly acidic ion exchanger for lowering the pH of a solution mixed with a liquid and hypochlorite, and an arsenic from the liquid. And a removal container containing an arsenic removing agent.
　本発明の装置は、弱酸性イオン交換体が充填されたカラムなどのイオン交換体充填容器をpH低下容器として備える。弱酸性イオン交換体は、上記のとおりの材料を使用することができる。イオン交換体充填容器を通過した次亜塩素酸塩溶液は、弱酸性イオン交換体と反応して液体のpHを低下することができる。 The apparatus of the present invention includes an ion exchanger-filled container such as a column packed with a weakly acidic ion exchanger as a pH lowering container. The weakly acidic ion exchanger can use the materials as described above. The hypochlorite solution that has passed through the ion exchanger filled container can react with the weakly acidic ion exchanger to lower the pH of the liquid.
　次いで、pH低下容器は、ヒ素除去剤を含む除去用容器に接続される。ヒ素除去剤は、上記のとおりの材料を使用することができる。pHが低下された液体が除去用容器中のヒ素除去剤と接触することにより、ヒ素を除去することができる。 Next, the pH lowering container is connected to a removing container containing an arsenic removing agent. As the arsenic removing agent, the material as described above can be used. Arsenic can be removed by the liquid having a lowered pH coming into contact with the arsenic removing agent in the removal container.
　本発明の装置は、たとえば以下のように使用する。まず、液体中の3価ヒ素含有イオンを5価ヒ素含有イオンに酸化するために、上記の通りの次亜塩素酸塩を溶液に添加する。たとえば、100mlの溶液からヒ素を除去して飲用水を生成する場合、溶液に10000ppmの次亜塩素酸ナトリウム溶液を数滴添加することにより、数ppm～数十ppmの次亜塩素酸ナトリウム溶液となる。この溶液をpH低下容器に導入する。導入された次亜塩素酸塩溶液は、そのpHが、ヒ素除去剤の吸着に適したpHであるpH5～7に低下される。続いて、溶液が除去用容器に導入される。除去用容器に導入された溶液は、ヒ素がヒ素吸着剤に吸着され、ヒ素が除去された溶液が生成される。 The apparatus of the present invention is used as follows, for example. First, in order to oxidize trivalent arsenic-containing ions in a liquid to pentavalent arsenic-containing ions, hypochlorite as described above is added to the solution. For example, when drinking water is produced by removing arsenic from a 100 ml solution, several drops to tens of ppm sodium hypochlorite solution can be obtained by adding a few drops of 10000 ppm sodium hypochlorite solution to the solution. Become. This solution is introduced into a pH lowering container. The pH of the introduced hypochlorite solution is lowered to pH 5-7, which is a pH suitable for adsorption of the arsenic removing agent. Subsequently, the solution is introduced into the removal container. In the solution introduced into the removal container, arsenic is adsorbed by the arsenic adsorbent, and a solution from which arsenic has been removed is generated.
　また、本発明の装置は、貯留容器をさらに備えていてもよい。たとえば、貯留容器において、液体と次亜塩素酸塩を混合しておく。この次亜塩素酸塩溶液を弱酸性イオン交換体が充填されたイオン交換体充填容器に接続しておき、貯留容器からイオン交換体充填容器へ溶液が導入される。また、貯留容器は、イオン交換体充填容器へ溶液を導入するためのポンプをさらに備え、ポンプを介してイオン交換体充填容器に接続してもよい。 Moreover, the apparatus of the present invention may further include a storage container. For example, a liquid and hypochlorite are mixed in a storage container. The hypochlorite solution is connected to an ion exchanger filled container filled with a weakly acidic ion exchanger, and the solution is introduced from the storage container into the ion exchanger filled container. The storage container may further include a pump for introducing the solution into the ion exchanger filling container, and may be connected to the ion exchanger filling container via the pump.
　また、一つの態様において、イオン交換体とヒ素除去剤とは、混合して使用することができる。この場合、pH低下容器と除去用容器とは別々の容器にする必要はなく、単一の容器にイオン交換体とヒ素除去剤との混合物を充填するだけでよい。この混合物に液体を通過させることにより、このカラムを通過させるだけで液体中のヒ素を酸化させることができ、ヒ素を吸着することができる。 Also, in one embodiment, the ion exchanger and the arsenic removing agent can be mixed and used. In this case, it is not necessary to separate the pH lowering container and the removing container from each other, and it is sufficient to fill the single container with the mixture of the ion exchanger and the arsenic removing agent. By passing the liquid through the mixture, arsenic in the liquid can be oxidized and adsorbed by simply passing through the column.
材料および方法　実施例1では、液体として、試薬ヒ素を蒸留水に添加して0.5ppmのヒ素濃度となるように原水を作製した。　 Materials and Methods In Example 1, as a liquid, reagent arsenic was added to distilled water to prepare raw water so as to have an arsenic concentration of 0.5 ppm. *
実施例2および3では、ヒ素標準液1000ppm（Merck Millipore）を蒸留水に添加して0.25ppmに希釈した。この溶液に亜ヒ酸ナトリウム水溶液6500ppm（Merck Millipore）を蒸留水に添加して0.25ppmにした。理論上は合計で0.5ppmのヒ素標準液＋亜ヒ酸ナトリウム水溶液を含む原水を作製した。　 In Examples 2 and 3, arsenic standard solution 1000 ppm (Merck Millipore) was added to distilled water and diluted to 0.25 ppm. To this solution, 6500 ppm of sodium arsenite aqueous solution (Merck Millipore) was added to distilled water to make 0.25 ppm. Theoretically, raw water containing a total of 0.5 ppm arsenic standard solution + sodium arsenite aqueous solution was prepared. *
実施例4では、ミャンマーで採取した地下水を原水として使用した。これらの地下水は、3価および5価のヒ素を含有することが分かっている。地下水は、0.03ppmのヒ素を含有した。　 In Example 4, groundwater collected in Myanmar was used as raw water. These groundwaters are known to contain trivalent and pentavalent arsenic. The groundwater contained 0.03 ppm arsenic. *
弱酸性イオン交換体として、アクリル系ダイヤイオン（登録商標）WK40L（三菱化学株式会社）を使用した。ヒ素吸着剤として、READ-As（株式会社日本海水）を使用した。活性アルミナとして、市販の活性アルミナを使用した。　 Acrylic Diaion (registered trademark) WK40L (Mitsubishi Chemical Corporation) was used as the weakly acidic ion exchanger. READ-As (Nihonkaikai Co., Ltd.) was used as an arsenic adsorbent. Commercial activated alumina was used as the activated alumina. *
ヒ素の含有量の測定は、エムクァント（商標）ヒ素テスト（Merck Millipore）およびヒ素メルコクァントヒ素テスト（超高感度タイプ）（Merck Millipore）を使用した。pHの測定は、pH　ポータブル水質計P-30（東亜DKK）を使用した。次亜塩素酸の測定は、ハンディ水質計“アクアブ”AQ-202型（柴田）を使用した。　 The arsenic content was measured using the Emquant ™ Arsenic Test (Merck Millipore) and the Arsenic Mercoquant Arsenic Test (Ultra Sensitive Type) (Merck Millipore). The pH was measured using a pH portable water quality meter P-30 (Toa DKK). For the measurement of hypochlorous acid, a handy water quality meter “AQUAB” AQ-202 type (Shibata) was used. *
実施例1　本発明の方法によるヒ素の除去効果の確認　本実施例では、試薬ヒ素を蒸留水に添加して0.5ppmのヒ素濃度となるように作製した原水からのヒ素除去を確認した。ヒ素吸着剤2ml＋弱酸性イオン交換体20mlを充填したカラム、活性アルミナ2ml＋弱酸性イオン交換体20mlを作製した。一方、弱酸性イオン交換体20mlを充填しただけのカラムも作製した。　 Example 1 Confirmation of Arsenic Removal Effect by the Method of the Present Invention In this example, arsenic removal from raw water prepared by adding reagent arsenic to distilled water to a concentration of 0.5 ppm was confirmed. A column packed with 2 ml of arsenic adsorbent + 20 ml of weak acid ion exchanger, 2 ml of activated alumina + 20 ml of weak acid ion exchanger were prepared. On the other hand, a column only packed with 20 ml of weakly acidic ion exchanger was also produced. *
結果　原水のヒ素含有量を測定すると、0.5ppmであった。一方、原水を弱酸性イオン交換体20ml＋ヒ素吸着剤2mlを充填したカラムに通した液体のヒ素含有量を測定すると、0.05ppmであった。ヒ素溶液を弱酸性イオン交換体で処理することにより、pHが低下してヒ素吸着の効果が高まることがわかる。本発明のヒ素除去方法により、非常に効率よくヒ素を除去することができた。　 Results The arsenic content of the raw water was measured and found to be 0.5 ppm. On the other hand, when the arsenic content of the liquid obtained by passing raw water through a column packed with 20 ml of weakly acidic ion exchanger + 2 ml of arsenic adsorbent was measured, it was 0.05 ppm. It can be seen that treating the arsenic solution with a weakly acidic ion exchanger lowers the pH and increases the effect of arsenic adsorption. Arsenic could be removed very efficiently by the arsenic removal method of the present invention. *
一方、弱酸性イオン交換体のみを充填したカラムに通した液体のヒ素含有量を測定すると、0.25ppmであった。弱酸性イオン交換体によってpHを低下させるだけでも、弱酸性イオン交換体にヒ素を吸着させることができた。　 On the other hand, when the arsenic content of the liquid passed through the column packed with only the weakly acidic ion exchanger was measured, it was 0.25 ppm. Arsenic could be adsorbed to the weak acid ion exchanger simply by lowering the pH with the weak acid ion exchanger. *
実施例2　本発明の方法による亜ヒ酸およびヒ素の活性アルミナによる除去効果の確認　本実施例では、試薬亜ヒ酸およびヒ素を蒸留水に添加して、それぞれを0.25ppm（合計0.5ppm）の濃度で含むように混合した原水からのヒ素除去を確認した。　 Example 2 Confirmation of removal effect of arsenous acid and arsenic by activated alumina by the method of the present invention In this example, reagent arsenic acid and arsenic were added to distilled water, and each of them was 0.25 ppm (total of 0.5 ppm). The removal of arsenic from the raw water mixed to include the concentration was confirmed. *
上記原水を、活性アルミナ250mlを充填したカラムおよび弱酸性イオン交換体500mlを充填したカラムを通した際のヒ素除去を確認した。　 Arsenic removal was confirmed when the raw water was passed through a column packed with 250 ml of activated alumina and a column packed with 500 ml of weakly acidic ion exchanger. *
以下の処理をした後のヒ素濃度およびpHを測定した。1.原水を無処理。2.原水を活性アルミナカラム通過。3.原水を弱酸性イオン交換体カラム通過。4.原水を弱酸性イオン交換体カラム通過、次いで活性アルミナカラム通過。　 The arsenic concentration and pH after the following treatments were measured. 1. Untreated raw water. 2. Raw water passes through activated alumina column. 3. Pass raw water through weakly acidic ion exchanger column. 4. Raw water is passed through a weakly acidic ion exchanger column and then through an activated alumina column. *
結果を以下に示す。
Figure JPOXMLDOC01-appb-T000001
 The results are shown below.
Figure JPOXMLDOC01-appb-T000001
ヒ素濃度0.4ppmの原水（ヒ素と亜ヒ酸等量混合物）は、ｐH7.9では活性アルミナを通してもヒ素濃度とｐHに変化が見られなかった（結果2）。弱酸性イオン交換体を通過するとpHがpH6.5に低下したが、ヒ素濃度は変化しなかった（結果3）。さらに活性アルミナを通過することでヒ素濃度が0.1ppmまで低下した（結果4）。　活性アルミナへのヒ素の吸着は、弱酸性領域において吸着率の高いことが知られている。弱酸性イオン交換体によって原水のpHを低下させることにより、大きな吸着力を得られる事がわかった。様々な条件の下で原水を弱酸性域とすることは、現場においては大変困難となる。弱酸性イオン交換体を通過するだけでｐHを容易に弱酸性にすることができ、活性アルミナのヒ素吸着率を格段に向上させることができた。　 The raw water with an arsenic concentration of 0.4 ppm (a mixture of equal amounts of arsenic and arsenous acid) showed no change in arsenic concentration and pH even when activated alumina was used at pH 7.9 (Result 2). After passing through the weakly acidic ion exchanger, the pH dropped to pH 6.5, but the arsenic concentration did not change (Result 3). Furthermore, the arsenic concentration decreased to 0.1 ppm by passing through activated alumina (Result 4). It is known that the adsorption of arsenic on activated alumina has a high adsorption rate in a weakly acidic region. It was found that a large adsorptive power can be obtained by lowering the pH of the raw water with a weakly acidic ion exchanger. It is very difficult on site to make raw water weakly acidic under various conditions. The pH can be easily made weakly acidic only by passing through the weakly acidic ion exchanger, and the arsenic adsorption rate of the activated alumina can be remarkably improved. *
実施例3　本発明の方法による亜ヒ酸およびヒ素の活性アルミナおよび次亜塩素酸による除去効果の確認　本実施例では、試薬亜ヒ酸およびヒ素を蒸留水に添加して、それぞれを0.25ppm（合計0.5ppm）の濃度で含むように混合した原水からのヒ素除去を確認した。また、次亜塩素酸ナトリウムは、このヒ素を含有する原水に50ppmの終濃度となるように添加した。　 Example 3 Confirmation of removal effect of arsenous acid and arsenic by activated alumina and hypochlorous acid by the method of the present invention In this example, reagent arsenic acid and arsenic were added to distilled water, and each was 0.25 ppm ( The removal of arsenic from the raw water mixed so as to include a concentration of 0.5 ppm in total was confirmed. Further, sodium hypochlorite was added to the raw water containing this arsenic so as to have a final concentration of 50 ppm. *
以下の処理をした後のヒ素濃度およびpHを測定した。1.原水を無処理。2.原水を活性アルミナカラム通過。3.原水に次亜塩素酸ナトリウム5ppmを添加。4.原水に次亜塩素酸ナトリウム5ppmを添加、次いで弱酸性イオン交換体カラム通過。5.原水に次亜塩素酸ナトリウム5ppmを添加、次いで原水を弱酸性イオン交換体カラム通過、次いで活性アルミナカラム通過。　 The arsenic concentration and pH after the following treatments were measured. 1. Untreated raw water. 2. Raw water passes through activated alumina column. 3. Add 5ppm sodium hypochlorite to raw water. 4. Add 5ppm sodium hypochlorite to raw water, then pass through weakly acidic ion exchanger column. 5. Add 5 ppm of sodium hypochlorite to the raw water, then pass the raw water through a weakly acidic ion exchanger column and then through an activated alumina column. *
結果を以下に示す。
Figure JPOXMLDOC01-appb-T000002
 The results are shown below.
Figure JPOXMLDOC01-appb-T000002
次亜塩素酸ナトリウムを添加すると、一旦原水のpHが高くなる。原水に次亜塩素酸ナトリウムを添加後に弱酸性イオン交換体を通過させると、pHは6.5まで低下した。この溶液をさらに活性アルミナを通過させると、溶液中のヒ素濃度は、0.05ppmまで低下した。亜砒酸は、ヒ素と比較して活性アルミナへの吸着が悪いことが知られている。次亜塩素酸ナトリウム添加により、亜ヒ酸が酸化されて容易にヒ素となる。さらに、弱酸性イオン交換体を通過させることにより、溶液のpHを飲用にも適したpHまで低下させることができると共に、活性アルミナへの吸着率がされる。 Once sodium hypochlorite is added, the pH of the raw water once increases. When sodium hypochlorite was added to the raw water and then passed through a weakly acidic ion exchanger, the pH dropped to 6.5. When this solution was further passed through activated alumina, the arsenic concentration in the solution decreased to 0.05 ppm. Arsenious acid is known to be poorly adsorbed on activated alumina as compared to arsenic. By adding sodium hypochlorite, arsenous acid is easily oxidized to form arsenic. Furthermore, by passing the weakly acidic ion exchanger, the pH of the solution can be lowered to a pH suitable for drinking, and the adsorption rate to the activated alumina is achieved.
　実施例4　ヒ素を含有するミャンマーの水からのヒ素の除去効果の確認
　本実施例では、ミャンマーで採取した地下水を原水として使用した。ヒ素吸着剤2ml＋弱酸性イオン交換体20mlを充填したカラム、活性アルミナ2ml＋弱酸性イオン交換体20mlを作製した。一方、弱酸性イオン交換体20mlを充填しただけのカラムも作製した。 Example 4 Confirmation of Arsenic Removal Effect from Myanmar Water Containing Arsenic In this example, groundwater collected in Myanmar was used as raw water. A column packed with 2 ml of arsenic adsorbent + 20 ml of weak acid ion exchanger, 2 ml of activated alumina + 20 ml of weak acid ion exchanger were prepared. On the other hand, a column only packed with 20 ml of weakly acidic ion exchanger was also produced.
　結果
　原水として地下水1のヒ素含有量を測定すると、0.03ppmであった。一方、ミャンマーの地下水を弱酸性イオン交換体20ml＋ヒ素吸着剤2mlを充填したカラムに通した液体のヒ素含有量を測定すると、検出限界以下であった。本発明のヒ素除去方法により、非常に効率よくヒ素を除去することができた。 Results The arsenic content of groundwater 1 as raw water was 0.03 ppm. On the other hand, when the arsenic content of the liquid that passed through Myanmar ground water through a column packed with 20 ml of weakly acidic ion exchanger + 2 ml of arsenic adsorbent was measured, it was below the detection limit. Arsenic could be removed very efficiently by the arsenic removal method of the present invention.
　また、原水および本発明の方法で処理した原水のそれぞれ50μlを寒天版に播種し、37℃にて22時間培養した。本発明の方法で処理した原水は、全く細菌が増殖しなかったが、処理していない原水は、細菌が増殖していた。 In addition, 50 μl each of raw water and raw water treated by the method of the present invention was seeded on an agar plate and cultured at 37 ° C. for 22 hours. Bacteria did not grow at all in the raw water treated by the method of the present invention, but bacteria grew in the untreated raw water.
　本発明であれば、原水を簡易かつ迅速にヒ素を除去することができ、かつ弱酸性の次亜塩素酸溶液を生成することができるため、有用な浄水装置として利用することができる。 According to the present invention, arsenic can be easily and quickly removed from raw water, and a weakly acidic hypochlorous acid solution can be generated. Therefore, it can be used as a useful water purifier.

Claims (3)

  1. 　ヒ素を含有する液体からヒ素を除去する方法であって、
    　前記液体と次亜塩素酸塩を混合する工程と、
    　前記混合溶液を弱酸性イオン交換体と接触させて、前記溶液のpHを低下させる工程と、
    　前記pHが低下した溶液をヒ素吸着剤と接触させて、前記液体からヒ素を除去する工程と、
    を含む方法。     A method for removing arsenic from a liquid containing arsenic,
    Mixing the liquid and hypochlorite;
    Contacting the mixed solution with a weakly acidic ion exchanger to lower the pH of the solution;
    Contacting the solution with reduced pH with an arsenic adsorbent to remove arsenic from the liquid;
    Including methods.
  2. 　前記ヒ素吸着剤は、活性アルミナである、請求項1に記載の方法。 The method according to claim 1, wherein the arsenic adsorbent is activated alumina.
  3. 　次亜塩素酸塩ヒ素を含有する溶液からヒ素を除去する装置であって、
    　前記液体と次亜塩素酸塩を混合した溶液のpHを低下させるための、弱酸性イオン交換体を含むpH低下容器と、
    　前記液体からヒ素を除去するための、ヒ素除去剤を含む除去用容器と、
    を備える装置。     An apparatus for removing arsenic from a solution containing hypochlorite arsenic,
    A pH-lowering vessel containing a weakly acidic ion exchanger for lowering the pH of a mixed solution of the liquid and hypochlorite;
    A removal container containing an arsenic remover for removing arsenic from the liquid;
    A device comprising:
PCT/JP2015/081663 2014-11-10 2015-11-10 Method and device for removing arsenic WO2016076335A1 (en)

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JPS5488655A (en) * 1977-12-24 1979-07-13 Sumitomo Metal Mining Co Method of treating plated waste water
JPS55132633A (en) * 1979-03-30 1980-10-15 Agency Of Ind Science & Technol Adsorbent for arsenic
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