TWI445671B - Cation exchanger and method of removing heavy metal ions in wastewater - Google Patents

Description

Cation exchanger and method for removing heavy metal ions from waste water

The present invention relates to a cation exchanger prepared by using plant biomass as a raw material, and a method for removing heavy metal ions in wastewater containing heavy metal ions by using the cation exchanger.

Protecting water bodies from heavy metal ions is an important technical challenge related to environmental protection. The increased awareness of the toxicity of heavy metal ions has led to stricter regulations on the emission of heavy metal ions. In order to comply with such emission regulations, there is a need for an ion removal method that is capable of removing heavy metal ions in heavy metal ion-containing wastewater at low cost, efficiency, and as easily as possible.

A number of methods have been proposed for removing heavy metal ions, such as in plant wastewater, such as agglomeration and settling, ion exchange, adsorption onto, for example, activated carbon, electrosorption and magnetic adsorption.

For example, Japanese Patent Application Laid-Open No. Hei 9-117776 (Technical Solution 1, pages 2 to 4) (hereinafter referred to as Patent Document 1) proposes an agglomeration and sedimentation method, which is first by adding a base to a heavy metal A method in which ionic wastewater forms a hydroxide such that most of the heavy metal ions are insoluble and then filtered through a cellulose filter to remove agglomerates.

It is impossible to remove residual ions by making the wastewater alkaline by making the heavy metal ions insoluble, such as ions which are soluble in the aqueous solution even under alkaline conditions, and change by forming complex ions under alkaline conditions. Get soluble ions. As a result, it is generally difficult to reduce the concentration of heavy metal ions in the wastewater to compliance with emission regulations only by agglutination and sedimentation methods. Therefore, the aqueous solution after the agglutination precipitation treatment is additionally subjected to ion exchange or adsorption treatment to reduce the concentration of heavy metal ions in the wastewater to a prescribed value or lower.

For example, Japanese Patent Application Laid-Open No. 8-168798 (Technical Solution 1, page 2 to page 5, FIG. 1) (hereinafter referred to as Patent Document 2) proposes a method for removing heavy metal ions in heavy metal-containing wastewater. By agglomerating heavy metals in the heavy metal-containing wastewater by adding alkali to the heavy metal-containing wastewater, the agglomerates are separated by solid-liquid separation, and the heavy metal ions in the alkaline wastewater are adsorbed to Removing a heavy metal ion in the alkaline wastewater by chelating a resin or a weakly acidic cation exchange resin, the method is characterized in that the pH of the alkaline wastewater after solid-liquid separation is adjusted to 5 or less, and then, The chelating resin or weakly acidic cation exchange is carried out by adsorbing the heavy metal ions in the wastewater to 60 to 100 equivalent % of the exchange group in the alkali metal or alkaline earth metal type, and wherein 0 to 40 equivalent % is H type Resin to remove the heavy metal ions.

Patent Document 2 describes that the alkaline waste water is acidified to pH 5 or lower after solid-liquid separation, so that the heavy metal elements contained in the waste water in the form of fine hydroxide or carbonate are dissolved into ions. The plasma is then treated with a cation exchange resin, which is effective for adsorbing heavy metal elements.

The weakly acidic cation exchange resin used is, for example, a carboxyl group-containing resin such as a copolymer of styrene, divinylbenzene, and acrylic acid or methacrylic acid. The plasma exchange resin is typically a synthetic product made from oil or natural gas that is costly and results in wasted resources and becomes an environmental contaminant when discarded after use. Therefore, when the ion exchange resin after use is returned to the original state by the regeneration treatment, the plasma exchange resin can be reused.

As described above, it is generally difficult to sufficiently reduce the concentration of heavy metal ions in the wastewater by only the agglutination and sedimentation methods proposed in, for example, Patent Document 1. The method of using the ion exchange method as proposed in, for example, Patent Document 2 requires an additional step of pretreatment, regeneration treatment of the ion exchange resin, and disposal of the treated solution, which leads to an increase in the number of steps. And thus make the system more complicated. As a result, equipment cost and operating costs increase.

In view of the above, it is desirable to provide a disposable cation exchanger made from plant biomass as a raw material, and a simple and efficient method for removing heavy metal ions from wastewater by using it.

According to an embodiment of the present invention, there is provided a cation exchanger comprising at least one member selected from the group consisting of Corchorus olitorius, Brassica rapa var. peruviridis, Cryptotaenia japonica, Brassica rapa var . nipposinica) and spinach (Spinacia oleracea) group of leafy vegetables.

According to another embodiment of the present invention, there is provided a method for removing heavy metal ions in wastewater, comprising at least an adsorption step of: causing the wastewater containing heavy metal ions to include at least one selected from the group consisting of king vegetables, small pine, duck, and snow The cation exchanger of the leafy vegetables of the spinach is contacted, whereby a portion of the heavy metal ions are adsorbed onto the cation exchanger.

The cation exchanger according to an embodiment of the present invention is a cation exchanger prepared by using plant biomass selected from the group consisting of king vegetables, kimchi, duck celery, snow scallions, and spinach as a raw material, and therefore, Disposal and even incineration after use will not become an actual source of carbon dioxide emissions. As will be described in the examples below, the cation exchanger has cation exchange properties equivalent to or superior to synthetic cation exchange resins.

A method for removing heavy metal ions in wastewater according to an embodiment of the present invention includes the following adsorption step of contacting wastewater containing dissolved heavy metal ions with a cation exchanger such that a portion of the heavy metal ions are adsorbed onto the ion exchanger, thus The method can effectively remove heavy metal ions in wastewater. In addition, since the ion exchanger is disposable, the regeneration treatment step of the ion exchanger can be omitted, and a wastewater treatment system with simple and high processing efficiency can be constructed. Due to the high cation exchange performance of the cation exchanger, the amount of cation exchanger used can be reduced and the cation exchanger can be handled very easily after use.

The cation exchanger according to an embodiment of the present invention preferably includes a king dish. Preferably, the cation exchanger comprises dried, dried or dried roots of leafy vegetables.

In the method of removing heavy metal ions in wastewater according to another embodiment of the present invention, the cation exchanger used is preferably a cation exchanger comprising a king vegetable. The cation exchanger used is preferably a cation exchanger comprising dried leaves, dried stems or dried roots of leafy vegetables.

The adsorption step is preferably carried out by feeding the wastewater through an adsorption layer comprising a cation exchanger.

In this case, it is preferred to carry out the following steps before the adsorption step: adding alkali to the wastewater containing dissolved heavy metal ions to make the wastewater alkaline, thereby making at least part of the heavy metal ions insoluble and generating suspended solid matter And adding an inorganic coagulant to the wastewater to agglomerate and settle the suspended solid matter.

In this case, for example, the step of separating and removing the suspended solid matter in the wastewater by solid-liquid separation is preferably performed before the adsorption step. In this case, it is preferred to add a polymer coagulant to the wastewater prior to the adsorption step to cause the suspended solid matter to aggregate and settle, and thereby separate and remove the suspended solid matter in the wastewater. And the step of a polymeric coagulant.

Alternatively, preferably, the wastewater containing the suspended solid matter is fed through the above-mentioned adsorption layer to cause solid-liquid separation of the suspended solid matter in the adsorption layer, and thereby separating and removing it from the wastewater. Therefore, preferably, before the adsorption step, the polymer coagulant is added to the wastewater to cause the suspended solid matter to aggregate and settle out, and then the solid-liquid separation method is used to separate and remove the suspension in the wastewater in the adsorption layer. Solid material and polymer coagulant. It is also preferred to mix the polymer coagulant prior to the adsorption layer, and then feed the wastewater containing the suspended solid material through the adsorption layer, and then perform solid-liquid separation in the adsorption layer to separate and remove the suspended state in the wastewater. Solid material.

The polymer coagulant used in this step is preferably a nonionic polymer coagulant and/or an anionic polymer coagulant. For example, the polymer coagulant used is polypropylene decylamine and/or a hydrolyzate thereof.

Hereinafter, a cation exchanger according to an embodiment of the present invention and a method of removing heavy metal ions in wastewater are described in detail with reference to the embodiments of the present invention. However, it should be understood that the invention is not limited to the embodiments.

[Cation exchanger]

After intensive research, the inventors have found that a leafy vegetable group consisting of a king vegetable, a small pineapple, a duck celery, a snow stalk, and a spinach has a cation exchange property equivalent to or superior to that of a synthetic cation exchange resin. Points will be described in the examples below. It is presumed that the cation exchange function can be effectively performed by the carboxyl group and the hydroxyl group of the pectin, folic acid, acidic polysaccharide (specifically, D-glucuronic acid and D-galacturonic acid) and other substances which are composed of leafy vegetables.

The leafy vegetables used as the cation exchanger may be any part of leafy vegetables (i.e., leaves, stems or roots), however, from the viewpoint of efficient use of resources, it is better to use less stems and root portions for consumption. Further, leafy vegetables in any state (i.e., as they are, after drying, or after extraction with various solvents or aqueous solutions) may be used, however, due to simplicity and ease of handling, they are preferably used as they are or after drying. Further, the shape may be as it is, however, a milled product having a large surface area such as a dry powder may have strong ion exchange properties.

Since leafy vegetables are high water content products with a water content of up to 90 to 95% by weight, dried products of leafy vegetables are highly compatible with water. With regard to the above properties, it is considered that the water-soluble pectin per unit dry mass can be in contact with water over a large area, and thus has high ion exchange performance.

Examples of such leafy vegetables to be used include king vegetables, small pineapple, duck celery, snow scorpion and spinach, and among the above-mentioned leaf vegetables, king vegetables have high ion exchange properties. It may be because, unlike other leafy vegetables, Wang Cai contains many mucins.

If Wang cuisine is produced in Japan (such as Gunma Prefecture, Mie Prefecture, Zuohe County, or Okinawa Prefecture) or abroad (such as Egypt, Philippines, Malaysia, or China), there is no difference. However, from the viewpoint of environmental load and transportation cost, the closer the production location is to the place of use, the better. The method of drying the king dish may be any one of the following: dry day drying, hot air drying, freeze drying, freeze drying, vacuum drying, etc. However, overheating may cause a decrease in the molecular weight and intramolecular crosslinking of the acidic glycan which constitutes the king vegetable. The carbonization reaction and the metal ion adsorption efficiency are lowered, and therefore, the drying temperature is desirably 200 ° C or lower.

[Method of removing heavy metal ions from wastewater]

Examples of heavy metal ions contained in the wastewater include copper (Cu) ions, nickel (Ni) ions, chromium (Cr) ions, lead (Pb) ions, cadmium (Cd) ions, cobalt (Co) ions, and zinc (Zn) ions. . The heavy metals are present in the form of suspended solids such as hydroxides or in the form of metal ions and complex ion states. The concentration of such heavy metal ions in the wastewater is from about 1 to 1000 ppm.

The adsorption step can be carried out at any time by contacting the wastewater containing dissolved heavy metal ions with a cation exchanger comprising a leafy vegetable selected from the group consisting of king vegetables, small pine, duck, snow, and spinach, and making a portion of the heavy metal The ions are adsorbed onto the ion exchanger. For example, the heavy metal ion-containing wastewater can be brought into direct contact with the cation exchanger. Preferably, however, prior to performing the adsorption step, it is preferred to add a base to the wastewater containing dissolved heavy metal ions to make the wastewater alkaline so that at least a portion of the heavy metal ions are insoluble and produce a suspended solid material. And adding an inorganic coagulant to the waste water to agglutinate the suspended solid matter, because the residual ions which are not precipitated in the suspended solid matter can be effectively removed by adsorption. There is also no particular restriction on the form in which the wastewater is contacted with the cation exchanger, but the contacting is usually carried out by feeding the wastewater through, for example, a cation exchanger containing the adsorption layer packed in the adsorption column. In the following, such an example will be described.

1 is a flow chart showing the steps of removing heavy metal ions in wastewater containing dissolved heavy metal ions in accordance with an embodiment of the present invention. The case where the heavy metal ion used is copper (II) ion and the inorganic coagulant used is iron (III) chloride will be described by way of example in FIG.

First, a base is added to the wastewater containing heavy metal ions to make the wastewater alkaline. Preferably, the hydroxide is added as a base (such as calcium hydroxide Ca(OH) ₂ or sodium hydroxide NaOH) and the pH of the wastewater is usually adjusted to a pH of from 7 to 14, preferably from 8 to 12, although desired. The pH depends on the type of wastewater. Too little addition results in a decrease in the heavy metal ion removal effect, and excessive addition is economically disadvantageous.

In this way, most of the corresponding heavy metal ions become insoluble hydroxides and oxides, producing suspended solids. For example, most copper (II) ions are converted to copper (II) hydroxide, Cu(OH) ₂ by the following reaction:

Cu ²⁺ +2OH ^- →Cu(OH) ₂

However, some metal ions are dissolved in an aqueous solution even under alkaline conditions, or may form complex ions under alkaline conditions.

Then, an inorganic coagulant such as iron (III) chloride is added to the wastewater. The iron (III) ion added in this step is converted into iron (III) hydroxide by the following reaction, Fe(OF) ₃ :

Fe ³⁺ +3OH ^- →Fe(OH) ₃

The previously produced copper (II) hydroxide will coalesce with iron (III) hydroxide.

A polymeric coagulant is then added. The polymer coagulant further coalesces the previously formed suspended solid matter by, for example, coalescing into a floc with an inorganic coagulant, thereby making solid-liquid separation easier. The polymer coagulant to be used is preferably a nonionic polymer coagulant and/or an anionic polymer coagulant such as polyacrylamide and/or its hydrolyzate or sodium polyacrylate. The amount of the polymer coagulant added is usually from 0.01 to 1000 ppm, preferably from 0.1 to 100 ppm, more preferably from 0.5 to 10 ppm, although it depends on the type of waste water and the molecular weight of the polymer coagulant. If desired, no polymeric coagulant may be added.

Then, the agglomerated suspended solid matter and the polymer coagulant are separated from the wastewater by a solid-liquid separation process to obtain primary treated water. The method of performing solid-liquid separation is not particularly limited, and preferably, for example, a sedimentation treatment method or a filtration method can be used.

In a method in which heavy metal ions are insoluble by making the wastewater alkaline, it is impossible to remove residual ions such as ions which are soluble in an aqueous solution even under alkaline conditions, and due to formation of a complex under alkaline conditions. It is still in dissolved state, so metal ion removal is limited.

Therefore, in this embodiment, the adsorption step is then carried out by feeding the primary treated water through an adsorption layer comprising a cation exchanger containing leafy vegetables such as king vegetables. In this way, a part of the remaining heavy metal ions can be removed by adsorbing them onto the ion exchanger, and high-quality secondary treated water having a low metal ion concentration can be obtained. Since the cation exchanger made of plant biomass material (such as Wang Cai) can be discarded, the cation exchanger regeneration treatment step can be omitted, and a simple and highly efficient wastewater treatment system can be constructed. Due to the high cation exchange performance of the cation exchanger, the amount of the cation exchanger can also be reduced, and the cation exchanger after use can be easily handled.

Although an example of removing the suspended solid matter (and the polymer coagulant) in the wastewater by the solid-liquid separation step before the adsorption step has been described, it is also possible to feed the solid matter containing the suspended solid (and the polymer coagulant). The wastewater passes through the adsorption layer, and then the suspended solid matter in the wastewater is separated and removed by the adsorption layer in the solid-liquid separation process. The solid-liquid separation step can be omitted in this manner. In this case, the step of adding a polymer coagulant can also be omitted by incorporating a polymer coagulant prior to the cation exchange layer.

Since the leafy vegetables used in the present invention are plant biomass materials, the cation exchanger prepared from the leafy vegetables or the dried products thereof is safer to the human body and the environment than the conventional ion exchange resin, and can be consumed without consumption. Produced from renewable resources under mineral resources. Therefore, the present invention contributes to the protection of the global environment from the viewpoints of resource conservation, reduction of dangerous materials, and efficient use of waste.

Hereinafter, the present invention will be described more specifically.

<alkali>

The alkaline pH adjusting agent used in the present invention is, for example, one or more of the following: calcium hydroxide Ca(OH) ₂ , sodium hydroxide NaOH, magnesium hydroxide Mg(OH) ₂ , sodium carbonate Na ₂ CO ₃ , sodium citrate Na ₂ SiO ₃ , bentonite and coal ash (fly ash). The heavy metal ions in the suspended solid matter contained in the wastewater can be precipitated by oxidizing by adding such an alkaline pH adjusting agent.

<Inorganic Coagulant>

The inorganic coagulant is, for example, at least one of the following: iron (III) chloride (ferric chloride), aluminum sulfate, polyaluminum chloride (PAC), iron (II) sulfate (ferrous sulfate), polyferric sulfate (polymorph) Iron), sodium aluminate, green chlorinated chloride and modified alkaline aluminum sulfate. The suspended solid matter (such as a metal hydroxide) in the wastewater can be agglomerated by the addition of the inorganic coagulating agents. Further, by using the combination of the king vegetable and the inorganic coagulant, it is possible to adsorb not only the suspended solid matter in the wastewater but also the soluble metal ions, and thereby effectively remove the metal ions contained in the wastewater. The content of the inorganic coagulant added to the wastewater is usually from 1 to 50,000 ppm, preferably from 5 to 5,000 ppm, although it depends on the type of the wastewater. Too little addition results in low metal ion removal efficiency, however, too much addition is economically disadvantageous.

A commercially available organic coagulant can be used in combination. The organic coagulant is, for example, at least one of the following coagulating agents: dimethyl diallyl ammonium chloride, epichlorohydrin condensate, polyethyleneimine, alkyl dialkylate and polyalkylene polyamine condensate, A dicyanamide-formalin condensate, an aniline-formaldehyde multiple complex hydrochloride, a polyhexamethylene thiourea acetate, and a polyvinylbenzyltrimethylammonium chloride. The content of the organic coagulant added is usually from 1 to 10,000 ppm, preferably from 5 to 1000 ppm.

<Polymer Coagulant>

The polymer coagulant used in the present invention includes a nonionic polymer coagulant, an anionic polymer coagulant, a cationic polymer coagulant, and an amphoteric polymer coagulant.

(non-ionic polymer coagulant)

- Polyacrylamide, polymethacrylamide, starch, guar, gelatin, polyethylene oxide and polypropylene oxide

(anionic polymer coagulant)

- (meth)acrylic polymers, such as partial hydrolyzates of polyacrylamide and polymethacrylamide, copolymers of acrylic or methacrylic acid with acrylamide or methacrylamide and their salts, acrylic acid or Terpolymer of methacrylic acid, acrylamide or methacrylamide and 2-propenylamine-methylpropanesulfonic acid, vinyl niobic acid or vinyl methanesulfonic acid and its salt, polyacrylamide And sulfomethyl compounds of polymethacrylamide and its salts; sodium alginate, guar gum sodium salt, carboxymethyl cellulose sodium salt, starch sodium salt

- Examples of other polymers are sulfonated compounds of the following polymer compounds and salts thereof: polystyrene, polyphenylene ether, polycarbonate, polyphenylene sulfide and polyethylene terephthalate; preferably polyphenylene Ether and polycarbonate.

(cationic polymer coagulant)

a quaternary compound of a dialkylaminoalkyl (meth)acrylate (a quaternizing agent such as methyl chloride or benzyl chloride) and a salt thereof formed with an acid (the salt formed with an acid is, for example, an inorganic salt) (such as hydrochloride or sulfate) or an organic salt (such as acetate), or a polymer or copolymer of such a quaternary compound with (meth) acrylamide; for example, from dimethylamino acrylate a quaternary compound of an ester and methyl chloride or a polymer or copolymer of the compound and acrylamide;

a quaternary compound derived from a dialkylaminoalkyl (meth) acrylamide or a salt thereof with an acid, or a polymer or copolymer of the quaternary compound with (meth) acrylamide, such as Copolymer of quaternary compound derived from dimethylaminopropyl acrylamide and methyl chloride with acrylamide

- a cationically modified polyacrylamide, such as a Mannich modified product of polypropylene decylamine and a Hofmann degradation product;

An epichlorohydrin-amine condensate, such as a polycondensate derived from epichlorohydrin and an alkylenediamine having 2 to 8 carbon atoms;

- Polydimethyldiallyl ammonium chloride

- Polyvinylimidazoline and its salts

- Polyvinyl ruthenium and its salts

- Chitin and its salts

- Polyvinylpyridine and its salts

- Polythiourea

- Water soluble aniline resin

- Chloromethylated polystyrene ammonium or quaternary amine salt

- Polyvinylimidazole and its salts

(amphoteric polymer coagulant)

- acrylamide-acrylic acid (or its salt)-dialkylaminoalkyl (meth)acrylate (or its salt and its quaternary compound)

- Polyglutamine and its salts

<Other>

In addition to the above coagulating agents, secondary treatment reagents such as ion exchange resins, ion exchange membranes, and other secondary treatment reagents may be used in combination or in combination.

(ion exchange resin)

The ion exchange resin used in the present invention is, for example, an anionic or cationic ion exchange resin. The anion exchange resin is generally a strongly basic anion exchange resin obtained by halomethylating a crosslinked styrene-divinylbenzene copolymer and then reacting a halomethyl group with a tertiary amine, or having a spacer group in the structure. Anion exchange resin. On the other hand, in the case of a strongly acidic cation exchange resin, a sulfonated compound of a crosslinked styrene-divinylbenzene copolymer is generally used as an ion exchange resin for producing ultrapure water. In the plasma exchange resin, a cation exchange resin is suitable for removing heavy metal ions. The amount added is 0.01 to 100 times higher than the amount added by Wang Cai, preferably 0.1 to 10 times higher, although it depends on the type of waste water.

(other chemicals used in combination)

The cation exchanger according to an embodiment of the present invention may be mixed or used in combination with a secondary treatment reagent such as a chelate resin, a chelating agent, activated carbon, ozone water, a water absorbent resin, a hydrogen peroxide solution, chlorine and liquid chlorine, and sodium hypochlorite. , chlorine dioxide, bleaching powder, chlorine isocyanuric acid, diatomaceous earth, photocatalyst (such as titanium oxide) or biological treatment agent.

<Method of separating insoluble components>

In the case of using Wang Cai, a conventional dehydrator can be used in a method of adsorbing and separating the metal ion-insoluble component contained in the wastewater. For example, a filter press, a vacuum dehydrator, a belt press dehydrator, a centrifugal dehydrator or a screw press can be used. The anhydrate (cake) can be recovered by a known method. It can also be easily converted into fuel or compost.

[Example]

Hereinafter, examples of the invention and comparative examples will be described. However, it should be understood that the present invention is not limited to the following examples.

[Example 1]

Example 1 experimentally confirmed that dried king powder has a role as a cation exchanger.

[Example 1-1]

First, a 0.05 mol/L sodium carbonate aqueous solution was prepared using sodium carbonate Na ₂ CO ₃ (manufactured by Wako Pure Chemical Industries Co., Ltd.) and ion-exchanged water. The aqueous solution contained sodium ion Na ^{+ at} a concentration of 0.1 mol/L.

Then, dried leaf powder, dried stem powder, and dried root powder (manufactured by K. Kobayashi & Co., Ltd.) of Wangcai were added to the aqueous sodium carbonate solution as a cation exchanger, and the mixture was stirred overnight. Then, the dried king vegetable powder of Wang Cai was added in an amount of 1% based on the mass of the aqueous sodium carbonate solution, and then the solid matter was filtered off to obtain a filtrate (1).

A plurality of king powders have a function as a cation exchanger. After the above treatment, a part of the hydrogen atoms in the acidic group in the cation exchanger are released into the aqueous solution in the form of hydrogen ions, and the sodium ions in the aqueous solution are replaced by Into the cation exchanger. The hydrogen ions released into the aqueous solution combine with the carbonate ion CO ₃ ^2- to form a hydrogencarbonate ion HCO ₃ ^- . The reaction formula (and the ion reaction formula) is as follows (wherein R represents a basic group of a cation exchanger, and a carbonyl group represents an acidic group).

R-COOH+Na ₂ CO ₃ →R-COONa+NaHCO ₃ (Reaction formula 1)

(R-COOH+Na ⁺ +CO ₃ ^2- →R-COO ^- Na ⁺ +HCO ₃ ^- )

Subsequently, the filtrate (1) was neutralized by neutralization with 0.1 mol/L hydrochloric acid, and the acid titer required to reach the first neutralization point was determined. The hydrogen ion of hydrochloric acid is then combined with the carbonate ion CO ₃ ^2- to form a hydrogencarbonate ion HCO ₃ ^- . The reaction formula (and ion reaction formula) is as follows.

HCl+Na ₂ CO ₃ →NaCl+NaHCO ₃ (Reaction formula 2)

(H ⁺ +CO ₃ ^2- →HCO ₃ ^- )

[Example 1-2]

The dried king powder was added to an aqueous sodium carbonate solution in an amount of 5% by mass based on the mass of the aqueous sodium carbonate solution to serve as a cation exchanger. In addition to the above changes, the aqueous sodium carbonate solution was treated in the same manner as in Example 1-1 to give a filtrate (2). This filtrate (2) was titrated by neutralization, and the titer of the first neutralization point was determined.

Further, an untreated sodium carbonate aqueous solution was also titrated by neutralization using 0.1 mol/L hydrochloric acid, and the titration amount reaching the first neutralization point was measured.

Since the carbonate ion is not consumed in the reaction formula 1 of the untreated sodium carbonate aqueous solution, the titration amount of the hydrochloric acid required for the reaction 2 is the largest in the three titration. Contrary to Examples 1-1 and 1-2, several king powders have a cation exchange effect, and the titration of hydrochloric acid required for the reaction 2 will become smaller because carbonate ions are consumed in the reaction 1. Therefore, the amount of ion exchange in Reaction 1 can be estimated based on the difference between the hydrochloric acid titration of the untreated sodium carbonate aqueous solution and the titration measured in Example 1-1 or 1-2.

Figure 2 is a graph showing the titration of untreated sodium carbonate aqueous solution and the solutions of Examples 1-1 and 1-2. In the three titrations, as expected, the titration of hydrochloric acid required for (Reaction 2) was the largest in the titration of the untreated sodium carbonate aqueous solution. The difference between the titer of 29.1 mL for the untreated sodium carbonate aqueous solution and the 25.2 mL for the filtrate (1) or 12.9 mL for the filtrate (2) was 3.9 mL or 16.2 mL, respectively. According to the above numerical values, the ratio of the ion exchange amount of the example 1-1 to the example 1-2 was 3.9:16.2=about 1:4.2, and it was more in accordance with the dry king powder of the examples 1-1 and 1-2. The addition ratio is 1:5. The above results confirmed that the dried king powder showed reproducible ion exchange.

[Example 2]

Example 2 It was confirmed experimentally that the dry powder of Wangcai, Komatsu, Yak, Celery and Spinach had the function of acting as a cation exchanger and removing the presence of copper (II) ions (heavy metal ions in wastewater).

[Example 2-1]

First, an aqueous copper acetate solution containing copper (II) ion Cu ²⁺ at a concentration of 3 ppm by mass was obtained by using copper (II) acetate (manufactured by Kanto Chemicals Co., Inc.) and ion-exchanged water.

Subsequently, dried cabbage leaf powder, dried stem powder, and dried root powder (manufactured by K. Kobayashi & Co., Ltd.) were added to an aqueous copper acetate solution as a cation exchanger, and the mixture was stirred for 1 hour. The dried king powder was added in an amount of 5 ppm based on the mass of the aqueous copper acetate solution. Then, the solid matter was removed by filtration, and the concentration of the copper (II) ion in the obtained filtrate was measured. The concentration of copper ions in the aqueous solution was measured by inductively coupled plasma atomic emission spectrometry (ICP-AES) using ICPE 9000 (trade name; manufactured by Shimadzu Corporation). The remaining copper acetate aqueous solution which has not been used is used as a copper (II) ion concentration standard solution (this concentration will be applied later).

During the treatment, the hydrogen atom in a part of the acidic group of the cation exchanger is released into the aqueous solution as hydrogen ions, and the copper (II) ion Cu ^{2+ in} the aqueous solution is instead incorporated into the cation exchanger, thus The concentration of copper (II) ions in the aqueous solution is decreased. Therefore, the amount of reduction in the concentration of copper (II) ions corresponds to the amount of ion exchange in (Reaction 3), and shows the performance of the cation exchanger as a heavy metal ion scavenger.

[Example 2-2]

Dry pine meal powder was added to the copper acetate aqueous solution instead of dried king vegetable powder to serve as a cation exchanger, and the content of dried kombu is 5 ppm with respect to the mass of the copper acetate aqueous solution. The dried pineapple powder is obtained by drying the purchased pineapple raw material in a drier and then pulverizing the dried komatsu. In addition to the above changes, the aqueous copper acetate solution was treated in the same manner as in Example 2-1, and the concentration of copper (II) ions in the obtained filtrate was measured.

[Example 2-3]

The dried duck celery powder was added to the aqueous copper acetate solution instead of the dried king vegetable powder to serve as a cation exchanger, and the content of the dried duck celery powder was 5 ppm with respect to the copper acetate aqueous solution. The dried duck celery powder was prepared by a method similar to that of Example 2-2 by drying the raw material of the duck celery in a drier and pulverizing the dried duck celery. In addition to the above changes, the copper acetate aqueous solution was treated in the same manner as in Example 2-1, and the concentration of the copper (II) ion in the obtained filtrate was measured.

[Example 2-4]

The dried sorghum powder was added to the aqueous copper acetate solution instead of the dried king powder to serve as a cation exchanger, and the content of the dry snow glutinous powder was 5 ppm with respect to the copper acetate aqueous solution. The dry snow powder was prepared by our method in the same manner as in Example 2-2 by drying the raw materials of the snow in the drier and pulverizing the dried snow. In addition to the above changes, the copper acetate aqueous solution was treated in the same manner as in Example 2-1, and the concentration of the copper (II) ion in the obtained filtrate was measured.

[Example 2-5]

Dry spinach powder was added to the aqueous copper acetate solution instead of dried king vegetable powder to serve as a cation exchanger, and the content of the dried spinach powder was 5 ppm with respect to the copper acetate aqueous solution. The dried spinach powder was prepared by a method similar to that of Example 2-2 by drying the purchased spinach raw material in a drier and pulverizing the dried spinach. In addition to the above changes, the copper acetate aqueous solution was treated in the same manner as in Example 2-1, and the concentration of the copper (II) ion in the obtained filtrate was measured.

[Comparative Example 2-2]

Amberlite IR124 (trade name; manufactured by Rohm and Haas Japan Co., Ltd. and distributed by Organo Corporation) is a strongly acidic cation exchange resin which is added to an aqueous copper acetate solution at 5 ppm instead of the cation exchanger. In addition to the above changes, the aqueous copper acetate solution was treated in the same manner as in Example 2, and the concentration of the copper (II) ion in the obtained filtrate was measured.

[Comparative Example 2-1]

A polymer coagulant Sanfloc NOP (trade name; manufactured by Sanyo Chemical Industries Co., Ltd.) was added to an aqueous copper acetate solution at 5 ppm instead of the cation exchanger. In addition to the above changes, the aqueous copper acetate solution was treated in the same manner as in Example 2, and the concentration of the copper (II) ion in the obtained filtrate was measured.

Table 1 is a table showing measured values of copper (II) ion concentrations in Examples 2-1 to 2-5 and Comparative Examples 2-1 and 2-2. The copper (II) ion concentration in this table is expressed as a percentage of the standard copper (II) ion concentration (100%) in the untreated copper acetate aqueous solution.

[Table 1]

Table 1 illustrates the following. In all of Examples 2-1 to 2-5 in which dry leaf powder was added, the copper (II) ion concentration decreased, indicating that the added dry leaf powder had ion exchange and heavy metal removal properties. Its effectiveness from high to low is king dish, small pineapple, duck celery, snow scorpion, spinach. A comparison with the comparative examples shows that the heavy metal removal performance of the leafy vegetables is equivalent to or three times that of the strongly acidic ion exchange resin and the polymer coagulant used for wastewater treatment.

The present invention has been described with reference to the embodiments and examples. However, the present invention is not limited thereto, and it is to be understood that the invention may be appropriately modified without departing from the scope of the invention.

The present application is related to the subject matter disclosed in Japanese Priority Patent Application No. 2010-067376, filed on Jan.

It should be understood by those skilled in the art that various modifications, combinations, sub-combinations and changes may be made in accordance with the design requirements and other factors, as long as they are within the scope of the accompanying claims or their equivalents.

1 is a flow chart showing the steps of removing heavy metal ions in wastewater containing heavy metal ions according to an embodiment of the present invention;

Figure 2 is a graph showing the titration curve of an untreated sodium carbonate aqueous solution and the titration curves obtained from Examples 1-1 and 1-2 according to an example of the present invention.

(no component symbol description)

Claims (15)

A cation exchanger comprising at least one member selected from the group consisting of Corchorus olitorius, Brassica rapa var. peruviridis, Cryptotaenia japonica, Brassica rapa var. nipposinica, and Spinacia oleracea. The leafy vegetables of the group. A cation exchanger as claimed in claim 1, which additionally comprises a king dish. The cation exchanger of claim 1, which additionally comprises dried leaves, dried stems or dried roots of leafy vegetables. A method for removing heavy metal ions in wastewater, comprising at least the following adsorption step: exchanging wastewater containing heavy metal ions with cations including at least one leafy vegetable selected from the group consisting of king vegetables, small pineapple, duck celery, snow scallions, and spinach The device is contacted whereby a portion of the heavy metal ions are adsorbed onto the cation exchanger. A method of removing heavy metal ions in wastewater according to claim 4, wherein a cation exchanger comprising a king vegetable is used as the cation exchanger. A method of removing heavy metal ions in wastewater according to claim 4, wherein a cation exchanger comprising dried leaves, dried stems or dried roots of leafy vegetables is used as the cation exchanger. A method of removing heavy metal ions in wastewater according to claim 4, wherein the adsorbing step is carried out by feeding the wastewater through an adsorption layer comprising a cation exchanger. The method of claim 7, wherein the method of removing heavy metal ions in the wastewater further comprises: adding a base to the wastewater containing heavy metal ions before the adsorption step to make the wastewater alkaline and at least partially heavy metal ions in an insoluble state, Thereby, a suspended solid matter is formed; then an inorganic coagulant is added to the wastewater, whereby the suspended solid matter is aggregated and settled. The method of claim 8, wherein the method of removing heavy metal ions in the wastewater further comprises: separating and removing the suspended solid matter in the wastewater by solid-liquid separation before the adsorption step. The method of claim 9, wherein the method further comprises: adding a polymer coagulant to the wastewater to cause agglomerated suspended solid matter to aggregate and settle, and then separating and removing the heavy metal ions in the wastewater. The suspended solid material in the wastewater and the polymer coagulant. The method for removing heavy metal ions in wastewater according to claim 8, further comprising: feeding waste water containing the suspended solid matter through the adsorption layer, and then solid-liquid separating the suspended solid matter in the adsorption layer, thereby from the wastewater It was removed and separated. A method of removing heavy metal ions in wastewater according to claim 11, further comprising: adding a polymer coagulant to the wastewater prior to the adsorption step, thereby causing the suspended solid matter to aggregate and settle, thereby causing the suspended solids The substance and the polymer coagulant are solid-liquid separated in the adsorption layer, whereby they are removed and separated from the wastewater. The method of claim 11, wherein the method further comprises: mixing a polymer coagulant prior to the adsorption layer, and then feeding the wastewater containing the suspended solid material through the adsorption layer, and subsequently the suspended solid material The solid-liquid separation in the adsorption layer is thereby removed and separated from the wastewater. A method of removing heavy metal ions in wastewater according to any one of claims 10, 12 and 13, wherein a nonionic polymer coagulant and/or an anionic polymer coagulant is used as the polymer coagulant. A method of removing heavy metal ions in waste water according to claim 14, wherein polypropylene decylamine and/or a hydrolyzate thereof is used as a polymer coagulant.