JP2010260030A - Adsorbent for adsorbing contaminating component and method for producing the adsorbent - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an adsorbent for adsorbing contaminating components, which has the performance equal to that of the conventional adsorbent when used for adsorbing contaminating components and the adsorptive effect of which is continued for a long time and to provide a low-cost method for producing the adsorbent for adsorbing contaminating components. <P>SOLUTION: The adsorbent for adsorbing contaminating components can be made low-cost since a hydrate of a cerium compound and ferric hydroxide are incorporated therein to exhibit high adsorption of the hydrate of the cerium compound and the ferric hydroxide and the ferric hydroxide is produced by using an iron material to produce the adsorbent at the cost lower than that of a rare earth metal compound-containing adsorbent. Even when the ferric hydroxide in the adsorbent is brought into contact with a reductive medium (for example, water) in the soil, such a reduction reaction can be restrained that the ferric hydroxide is converted into ferrous hydroxide to be eluted easily into the soil to attain such a good effect that the adsorptive performance of the adsorbent is continued. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention can provide an adsorbent for adsorbing contaminants such as heavy metals, in particular, at a low cost with performance equivalent to that of conventional expensive adsorbents, and further, an adsorbent for adsorbing contaminants that lasts for a long period of time. It relates to a manufacturing method.

  Conventionally, as a method of treating media (soil, ash, etc.) containing contaminating components such as fluorine and arsenic, the contaminated soil is fixed by excavating or removing the contaminated soil or using hydraulic cement or the like. And a technique such as changing the form of the contaminated component into a form that hardly dissolves in water and diffuses by using a chemical or the like.

  For example, in Patent Document 1, after contaminated soil is washed with a phosphoric acid aqueous solution, a sulfuric acid aqueous solution, or the like, arsenic components in the soil are insolubilized using an aqueous solution of lanthanum, cerium, iron salt, or the like, thereby suppressing diffusion. Technology is disclosed. Further, Patent Document 2 discloses a technique for insolubilizing arsenic by using an arsenic insolubilizing agent using a rare earth metal hydroxide such as cerium or lanthanum. Furthermore, Patent Document 3 discloses a heavy metal insolubilizing agent made of iron sulfide (II).

  Patent Document 4 discloses a technique for adsorbing arsenic in water or soil by using a special steel product such as Schwbertmannite in which a part of sulfate ions is replaced with calculated ions. Furthermore, Patent Document 5 discloses a technique for removing water-soluble selenium using a remover containing amorphous iron (III) hydroxide.

However, the techniques of Patent Documents 1 to 5 have the following problems.
Although the technique of Patent Document 1 has a certain effect for suppressing diffusion of arsenic, it requires a large amount of equipment for washing a large amount of soil, and requires a large amount of cerium, so that the processing cost increases. There is a problem. Moreover, since soil becomes acidic by washing with sulfuric acid or the like, there is a risk of adversely affecting living organisms in the treated soil.

  Although the technique of Patent Document 2 has a certain effect in terms of insolubilization of arsenic, it is difficult for rare earth oxides to dissolve in acid, and it is necessary to optimize extremely low pH, temperature and dissolution conditions. It is difficult to produce an insolubilizing agent. Furthermore, neutralization is carried out by treating with an alkali. However, when a salt generated during neutralization remains in the chemical and the chemical is used in contaminated soil, there is a possibility that an adverse effect due to the salt may occur.

  In the technology of Patent Document 3, iron sulfate, iron oxide, and iron acetate are industrial materials, and although the insoluble components can be insolubilized relatively inexpensively, the above iron compound is readily oxidized (for example, in the case of iron sulfide, There is a problem that the effect of the invention is not sustained because the effect of adsorbing contaminants is not exhibited unless the state is oxidized (from iron sulfide (II) to iron sulfide (III)).

  Although the technique of Patent Document 4 has an effect of adsorbing and fixing arsenic, since the mineral used is a special one, there is a problem that the manufacturing becomes complicated and as a result, the processing cost increases.

  Although the technique of Patent Document 5 can remove water-soluble selenium, amorphous iron hydroxide (III) used for the removal is reduced by contact with water in the ground, As a result of elution, there was a problem that the adsorbent itself caused heavy metal contamination. In addition, there is a problem that the cost required for producing amorphous iron hydroxide increases.

JP 2002-18421 A JP 2001-200366 A JP 2001-121130 A JP 2005-871 A Japanese Patent No. 3830878

  An object of the present invention is to provide a contaminating component adsorbent having a performance of adsorbing contaminating components equivalent to that of conventional adsorbents, and further providing an adsorbing effect for a long time and a method for producing the same.

  The inventors of the present invention have made extensive studies to solve the above problems. As a result, the contaminating component adsorbent contains a cerium compound hydrate and iron hydroxide, so that a high adsorption action of the cerium compound hydrate and iron hydroxide can be exhibited. It was found that the cost of the adsorbent can be reduced because it can be manufactured at a lower cost than the rare earth metal compound adsorbent. In addition, since hydrates of cerium compounds have properties as oxidizing agents, even when iron (III) hydroxide in the adsorbent comes into contact with a medium (such as water) in a reducing atmosphere such as in the soil. The present inventors have found that the reduction reaction that changes to iron (II) hydroxide, which is easily eluted in soil, can be suppressed, and that the adsorbent adsorption performance is highly effective.

The present invention has been made based on such findings, and the gist thereof is as follows.
(1) A contaminant adsorbent comprising a cerium compound hydrate and iron hydroxide.

(2) The contaminant adsorbent according to (1) above, wherein the iron hydroxide is deposited on or near the surface of the cerium compound hydrate.

(3) The contaminant adsorbent according to (1) or (2), wherein the iron hydroxide is deposited on or near the surface of the cerium compound hydrate.

(4) The contamination component adsorbent according to any one of (1) to (3), wherein the iron component constituting the iron hydroxide is Fe ³⁺ / (Fe ²⁺ + Fe ³⁺ ) ≧ 50 mass%.

(5) The contaminant adsorbent according to any one of (1) to (4), wherein the cerium constituting the hydrate of the cerium compound comprises trivalent cerium and / or tetravalent cerium.

(6) The contaminant adsorbent according to (5), wherein the ratio of tetravalent cerium in the cerium is 5% by mass or more.

(7) The contaminant adsorbent according to any one of (1) to (6), wherein the adsorbent further contains an inorganic material containing silica and aluminum.

(8) The contamination component adsorbent according to any one of (1) to (7), wherein the content of iron hydroxide in the adsorbent is 5 to 90% by mass.

(9) The pollutant component adsorbent according to any one of (1) to (8) above, wherein the cerium compound hydrate content in the adsorbent is 10 to 95% by mass.

(10) The above-mentioned contamination component is one or more components selected from the group consisting of arsenic, fluorine, boron, lead, cadmium, mercury, antimony, chromium, molybdenum, selenium, phosphorus, thallium, indium and bismuth ( The contaminant adsorbent according to any one of 1) to (9).

(11) A step of adding and mixing a cerium compound hydrate to a predetermined aqueous iron chloride solution to obtain a first mixed solution, and further adding an inorganic material containing silica and aluminum to the first mixed solution, A step of mixing to obtain a second mixed liquid, and adding an alkaline material to the second mixed liquid at a predetermined speed and mixing to make a suspension, and adjusting the pH of the turbid liquid to a range of 7 to 11 A step of precipitating iron hydroxide on the surface of the cerium compound hydrate in the suspension, and dehydrating the suspension to provide an adsorbent having the cerium compound hydrate and iron hydroxide. And a process for producing a contaminating component adsorbent, comprising the step of:

(12) The method for producing a contaminating component adsorbent according to (11), further comprising a step of adding and mixing an inorganic material containing silica and aluminum into the mixed solution.

(13) The method for producing a contaminating component adsorbent according to (11) or (12), further comprising a step of dehydrating the suspension in order to adjust the water content of the adsorbent.

(14) The method for producing a contaminated component adsorbent according to any one of (11) to (13), wherein the cerium compound hydrate is a cerium hydroxide compound or a cerium oxide compound.

(15) The method for producing the contaminant adsorbent according to any one of (11) to (14), wherein the suspension is dehydrated by a filter press method.

(16) The cerium constituting the cerium compound hydrate is composed of trivalent cerium and tetravalent cerium, and the ratio of tetravalent cerium in cerium is 5% by mass or more. (15) The manufacturing method of the contaminating component adsorbent according to any one of (15).

(17) The method for producing a contaminating component adsorbent according to any one of (11) to (16), wherein the adsorbent is dried at a temperature of 400 ° C. or lower to form a powder.

  ADVANTAGE OF THE INVENTION According to this invention, it becomes possible to provide the contaminating component adsorption agent and its manufacturing method which have the contamination component adsorption | suction performance equivalent to the conventional adsorption agent, and also the adsorption effect lasts for a long time at low cost. It was.

FIG. 1 is a flowchart for explaining a method for producing a contaminant adsorbent according to the present invention.

The contaminating component adsorbent and the method for producing the same according to the present invention will be described.
The contaminant adsorbent according to the present invention is characterized by containing a hydrate of cerium compound and iron hydroxide.

  By adopting the above-described configuration, it is possible to achieve the same effect of adsorbing contaminating components as conventional adsorbents due to the high adsorption action of cerium compound hydrates and iron hydroxide. In addition, since hydrates of cerium compounds have properties as oxidants, iron (III) hydroxide in the adsorbent is in contact with a reducing atmosphere medium such as water present in the contaminated soil. Moreover, the reaction which reduces to iron (II) hydroxide can be suppressed. Since iron hydroxide (II) is easier to elute than iron hydroxide (III), the reduction reaction can be effectively suppressed, and as a result, the adsorption performance can be highly effective. Furthermore, since the iron hydroxide contained in the adsorbent of the present invention uses iron as a material, the manufacturing cost can be greatly reduced as compared with an adsorbent composed only of a rare earth metal compound such as cerium or lanthanum.

Here, the cerium compound hydrate is usually synthesized by a liquid phase method and obtained in the form of cerium hydroxide hydrate or cerium oxide hydrate. Except for cerium hydroxide hydrate or hydrate of cerium oxide hydrate, a sufficient adsorption effect cannot be obtained. The cerium hydroxide hydrate and cerium oxide hydrate are amorphous when precipitated before drying or when dried at a low temperature, and are usually labeled as Ce (OH) ₄ .nH ₂ O. On the other hand, when dried at a high temperature, the same fluorite-type powder X-ray diffraction pattern as that of cerium oxide is obtained, which is denoted as CeO ₂ .nH ₂ O.

  In the contaminant adsorbent according to the present invention, the iron hydroxide is preferably deposited on or near the surface of the cerium compound hydrate. Since the cerium compound hydrate and the iron hydroxide are integrated, it is easy to obtain the effect of adsorbing contaminating components due to a synergistic effect, and a higher reduction effect of iron (III) hydroxide can be obtained. This is because sustainability is further improved. Here, the precipitation on or near the surface of the cerium compound hydrate means that the cerium compound serves as a nucleus, and the amorphous or crystalline substance of iron hydroxide on or near the surface (part of contact). The state in which a gel-like solid substance is present.

The iron hydroxide is mainly composed of iron (III) hydroxide from the viewpoint of obtaining a pollutant component adsorption effect. More specifically, the iron component constituting the iron hydroxide is Fe ³⁺ / It is preferable that (Fe ²⁺ + Fe ³⁺ ) ≧ 50 mass%. When Fe ³⁺ / (Fe ²⁺ + Fe ³⁺ ) is less than 50% by mass, the effect of elution of iron hydroxide (II) is greater than the coprecipitation effect of iron hydroxide (III), and the adsorbing power of contaminating components is sustained. This is because the effect may be reduced.

  Further, the cerium constituting the cerium compound hydrate is preferably composed of trivalent cerium and / or tetravalent cerium. Since trivalent cerium and tetravalent cerium have different types of contaminating components that can be adsorbed effectively, depending on the type of contaminating components contained in the soil, trivalent cerium and / or tetravalent cerium can be selected. Thus, the contaminated component can be processed more efficiently. Here, Table 1 shows the adsorption performance for each contaminating component of trivalent cerium and tetravalent cerium (the amount of contaminating component that can be adsorbed per gram of hydrate of cerium hydroxide compound (mg / g)). However, trivalent cerium is effective against arsenic, lead, and fluorine, and tetravalent cerium is effective against chromium, selenium, boron, and mercury. Furthermore, the proportion of tetravalent cerium in the cerium is 5% by mass or more from the viewpoint of exhibiting stable adsorption performance with respect to many contaminating components and the role of serving as a buffer for the medium in the reducing atmosphere. It is preferable that

  The shape of the cerium compound hydrate is not particularly limited, and may be granular or slurry. For example, in the case of a slurry state, water intervenes to suppress contact between the cerium surface and air, and the hydrate of the trivalent cerium compound is oxidized, so that the adsorption performance of the tetravalent cerium compound is low. It can prevent becoming a hydrate. However, when iron hydroxide is deposited on the surface of the cerium compound hydrate, the particle size of the cerium compound hydrate is preferably larger than the particle size of the iron hydroxide, It is preferably a single body such as granular, crushed or granular, or an aggregate thereof.

  Further, the adsorbent according to the present invention preferably further contains an inorganic material containing silica and aluminum. This is because an inorganic material containing silica and aluminum serves to adjust the concentration of the cerium compound hydrate and the iron hydroxide, and an adsorbent is added to the medium containing the contaminating component. When mixing, the adsorbing components are mixed more homogeneously, and the adsorbing effect of the contaminating components can be obtained more efficiently. This is because the optimum mixing conditions can be designed by appropriately adjusting the inorganic material since the amount of hydrate and iron hydroxide is determined.

  In addition, it is preferable that content of the iron hydroxide in the said adsorbent is 5-90 mass%. If the content of iron hydroxide is less than 5%, the content of iron hydroxide is too low, so that the adsorption capacity of the contaminated components, such as arsenic or selenium, that mainly exert the adsorption performance may decrease. In addition to this, it is difficult to obtain the effect of reducing the manufacturing cost of the adsorbent. On the other hand, if the content exceeds 90% by mass, the content of the cerium compound hydrate is lowered, so that there is a possibility that the desired contaminating component adsorption performance may not be obtained.

  Moreover, it is preferable that content of the hydrate of the cerium compound in the said adsorbent is 10-95 mass%. If the content of the cerium compound hydrate is less than 10% by mass, the adsorption action by the cerium compound hydrate is not small, and the adsorbent as a whole may not be able to obtain a sufficient contamination component adsorption effect, This is because if the content exceeds 95% by mass, the cerium compound hydrate content becomes too high, and the production cost reduction effect of the adsorbent of the present invention may not be obtained.

  Here, the contaminated component is a component that adversely affects the human body contained in the contaminated soil. For example, arsenic, fluorine, boron, lead, cadmium, mercury, antimony, chromium, molybdenum, selenium, phosphorus , One or more components selected from the group of thallium, indium and bismuth. By using the adsorbent of the present invention, it is possible to effectively exert an adsorption action on these contaminated components and suppress diffusion in the contaminated soil.

Next, the manufacturing method of the contaminating component adsorbent according to the present invention will be described with reference to the drawings. FIG. 1 is a flowchart for explaining a method for producing a contaminant adsorbent according to the present invention.
As shown in FIG. 1, the method for producing a contaminating component adsorbent according to the present invention includes a step of adding a cerium compound hydrate to a predetermined aqueous iron chloride solution and mixing to obtain a mixture (FIG. 1 (a)). In the mixed solution, an alkaline material is added and mixed at a predetermined speed to form a suspension, and the pH of the turbid solution is adjusted to a range of 7 to 11, so that the water of the cerium compound in the suspension is adjusted. A step of depositing iron hydroxide on or near the surface of the hydrate (FIG. 1 (c)), and a step of obtaining an adsorbent having a cerium compound hydrate and iron hydroxide (FIG. 1 (d)). It is characterized by that.

  By adopting the above configuration, the hydrate of the iron hydroxide and the cerium compound has the same contamination component adsorption performance as that of the conventional adsorbent, and further, the hydrate of the cerium compound is the iron hydroxide. (III) Suppresses reduction of iron hydroxide (II) and prevents it from flowing out into the soil, so it is possible to obtain a pollutant adsorbent with a long-lasting adsorption effect. Since an iron material is used, it can be manufactured at a low cost.

The liquid mixture is a liquid obtained by adding and mixing a particulate cerium compound hydrate to a predetermined aqueous iron chloride solution. Here, the iron chloride aqueous solution is not particularly limited as long as iron hydroxide can be generated by mixing with sodium hydroxide or the like in a later step. For example, ferric chloride aqueous solution (FeCl ₃ ) Alternatively, polyferric sulfate ([Fe ₂ (OH) _n (SO ₄ ) _{3-n / 2} ] m (0 <n, 0 <m)) can be used. Further, although the number of processes increases, ferrous chloride is used, and a process including an iron oxidation process using an oxidizing agent or the like can be used. Moreover, what is necessary is just to adjust conditions, such as a density | concentration of iron chloride aqueous solution, temperature, as needed.

  Moreover, about the cerium which comprises the hydrate of the cerium compound in the said liquid mixture, it consists of trivalent cerium and tetravalent cerium, and it is preferable that the ratio of tetravalent cerium is 5 mass% or more. Since trivalent cerium and tetravalent cerium have different types of contaminating components that can be effectively adsorbed, depending on the type of contaminating components contained in the soil, trivalent cerium and / or tetravalent cerium can be selected. From the viewpoint of more efficiently treating contaminating components, and also exhibiting stable adsorption performance for many contaminating components and serving as a buffer material for a medium in a reducing atmosphere, The proportion of tetravalent cerium in the cerium is more preferably 5% or more. The shape of the cerium compound hydrate is not particularly limited, and may be granular or slurry.

  Furthermore, it is preferable to perform a predetermined heat treatment on the mixed solution. This heat treatment dissolves the hydrate of the cerium compound added and mixed in the first mixed solution, and the surface of the hydrate of the cerium compound undergoes a hydration reaction, so that higher adsorption performance can be obtained. is there.

  Moreover, it is preferable to further include the process (FIG.1 (b)) which adds and mixes the inorganic material containing a silica and aluminum in the said liquid mixture. This is because the inorganic material serves to adjust the concentration of the cerium compound hydrate and the iron hydroxide. Here, the inorganic material is not particularly limited as long as it contains silica and aluminum, and any inorganic material can be added and mixed.

  The suspension is a suspension obtained by adding and mixing an alkali material at a predetermined speed in the mixed solution. Here, the alkali material is not particularly limited as long as it is a material that can react with iron ions of iron chloride to generate iron hydroxide, and for example, sodium hydroxide can be used. Moreover, there is no limitation in particular also about the alkaline material used when adjusting pH after that, Sodium hydroxide, slaked lime, magnesium oxide, aqueous ammonia, etc. can be used.

  Furthermore, it is preferable to dry the adsorbent at a temperature of 400 ° C. or lower to obtain a powder. This is because when the drying temperature exceeds 400 ° C., the hydroxyl group on the adsorbent surface disappears and the adsorbing performance is deteriorated.

  Thereafter, the adsorbent of the present invention is obtained from the suspension, and it is preferable to further include a step of dehydrating the suspension in order to adjust the water content of the adsorbent obtained. The dehydration method is not particularly limited as long as the liquid component of the suspension can be dehydrated. However, if the filter press method is used, the adsorbent obtained can be washed simultaneously with the dehydration treatment. Is preferable.

  The above description is merely an example of the embodiment of the present invention, and various modifications can be made within the scope of the claims.

Examples of the present invention will be described.
As Samples 1 to 6, as shown in FIGS. 1A to 1D, a trivalent cerium compound hydrate and a tetravalent cerium were added to a ferric chloride aqueous solution (concentration and mass are shown in Table 2). A step of adding a cerium compound hydrate comprising a hydrate of the compound (a ratio of a hydrate of a tetravalent cerium compound, the total mass is shown in Table 2) and mixing to obtain a first mixed solution; Into the first mixed solution, an inorganic material containing silica and calcium (the constituent materials and the total mass are shown in Table 2) are further added and mixed to obtain a second mixed solution; and in the second mixed solution, Add an alkaline material (type of alkali and addition rate shown in Table 2) at a predetermined speed, mix to make a suspension, and adjust the pH of the suspension to a predetermined range (about adjusted pH) Is shown in Table 2), and iron hydroxide is deposited on the surface of the cerium compound hydrate in the suspension. An adsorbent having a cerium compound hydrate and iron hydroxide (content of each component in the adsorbent is shown in Table 2) was produced by the process and the process of dehydrating the suspension using a filter. .

  Sample 7 was subjected to a heat treatment at 80 ° C. for 5 hours at the stage when the suspension was obtained to dissolve part of the cerium compound hydrate in the third suspension. Produced adsorbents under the same conditions as Samples 1-6.

  For samples 8 to 10, the obtained adsorbent was heated and dried using a batch type oven (250 ° C. × 1 hour for sample 8, 350 ° C. × 1 hour for sample 9, 450 ° C. for sample 10) × 1 hour), samples 8 and 9 are adsorbents with less moisture, and sample 10 is manufactured under the same conditions as samples 1-6 except that it is an adsorbent made of cerium hydroxide that is not a hydrate. did.

(Evaluation methods)
About the said sample, (1) Contamination component adsorption | suction performance, (2) Solubility of the iron component with reduced water, and (3) Manufacturing cost were evaluated.

(1) Adsorption of contaminating components Adsorbability of contaminating components is 400mL containing each contaminating component (arsenic, hexavalent chromium, tetravalent selenium, hexavalent selenium, boron, fluorine, mercury) at a concentration of 100 mg / L. In each solution, 1 g of the adsorbent of each sample was added, and the amount (mg / g) of each contaminating component that could be adsorbed per 1 g of the adsorbent was measured. The amount of contaminating component adsorbed was measured by adding the adsorbent to the solution and then rocking for 24 hours and examining the concentration of the solution thereafter. Heavy metals were measured by quantitative analysis using ICP (manufactured by Shimadzu Corporation, ICP-1000IV), and fluorine was measured by quantitative analysis using an ion meter. For samples 8 to 10, only the adsorption performance for arsenic was measured. Table 3 shows the measurement results.

(2) Solubility of iron component in reduced water Samples 1 and 3-8 were evaluated for the solubility of the iron component in reduced water. The solubility of iron components in reduced water can be found in Reference 1 (Tamoto, “14th Research Meeting on Groundwater and Soil Contamination and Prevention Measures”, Elution Characteristics of Heavy Metals from Tunnel Excavation under Oxidation and Reduction Conditions, 2008 The evaluation was conducted with reference to the contents described in the year. First, extract distilled water (3L vacuum bottle, approx. 2.5L), perform ultrasonic vacuum degassing, replace with 2L bottle, perform nitrogen bubbling for 1 hour, perform carbon dioxide bubbling for 5 minutes, and dissolve oxygen. Fixing, eliminating the bottle gap and capping with a tight stopper, gave reduced water having an oxidation-reduction potential of “−280 mV”. Next, 25 g of each sample is added to 250 mL of reduced water, shaken tow for 7 days, the liquid is recovered by centrifugation (3000 rpm, 20 minutes), and the concentration of iron present in the liquid pair is determined. It was evaluated by measuring. The concentration of iron dissolved in water was measured by quantitative analysis by an electric heating atomic absorption method (JIS K 0102 57.3). In addition, about each sample, it evaluated using the sample which adsorb | sucked arsenic or selenium. Table 3 shows the results of measuring the elution amounts (mg / L) of iron, arsenic and tetravalent selenium of each sample.

(3) Manufacturing cost for adsorption performance The raw material cost for each sample was divided by the adsorption performance of As that can be processed to calculate the raw material cost for the arsenic adsorption performance. And when the value of the raw material cost with respect to the adsorption | suction performance of the sample 6 was set to 1.0, the value of the raw material cost with respect to the adsorption | suction performance of another sample was calculated relatively, and it evaluated in accordance with the following references | standards. Note that the smaller the value of each sample, the more arsenic can be adsorbed to the sample 6 at a lower raw material cost.
◎: 0.5 or less ○: More than 0.5, less than 0.75 △: 0.75 or more, less than 1.0 ×: 1.0 or more

According to Table 3, (1) Regarding the adsorption performance of contaminating components, the samples (1-4, 7 and 9) corresponding to the examples are effective due to the synergistic effect of the cerium compound hydrate and iron hydroxide. It can be seen that the adsorption performance for the contaminating components is exhibited. On the other hand, it can be seen that the samples (5, 6 and 10) corresponding to the comparative examples do not sufficiently exhibit the adsorption performance.
(1) Regarding the adsorption performance of the contaminating component, since the heat drying temperature of Sample 10 is 450 ° C. exceeding 400 ° C., the cerium hydroxide in the adsorbent is no longer a hydrate, and the heat drying temperature is 250 ° C. It can be seen that the adsorbing power of the contaminating component is remarkably reduced as compared with the sample 8 which is a hydrate at 0 ° C. and the sample 9 which is a hydrate at a heat drying temperature of 350 ° C.
(2) Regarding the solubility of the iron component in the reduced water, a large amount of iron is eluted by the reduced water in the sample 6 not containing the cerium compound hydrate, which may adversely affect the environment. On the other hand, about other samples, it turns out that the elution of an iron component, arsenic, and tetravalent selenium can be suppressed effectively.
Furthermore, (3) Regarding production costs, Samples 1 to 4 and 6 to 9 containing iron as a material have Sample 5 containing only cerium hydroxide hydrate as an adsorbing component and only cerium hydroxide as an adsorbing component. It turns out that it can manufacture at low cost compared with the sample 10. FIG.

  According to the present invention, it is possible to provide a pollutant component adsorbent having a contaminant adsorbing performance equivalent to that of a conventional adsorbent and having an adsorption effect that lasts for a long time, and a method for producing the same, at a low cost. .

Claims (17)

  A contaminant adsorbent comprising a cerium compound hydrate and iron hydroxide.   The contaminant adsorbent according to claim 1, wherein the iron hydroxide is deposited on or near the surface of the cerium compound hydrate.   The contaminant adsorbent according to claim 1 or 2, wherein the cerium compound hydrate is a cerium hydroxide compound or a cerium oxide compound. The contamination component adsorbent according to any one of claims 1 to 3, wherein the iron component constituting the iron hydroxide is Fe ³⁺ / (Fe ²⁺ + Fe ³⁺ ) ≥50 mass%.   The cerium composing the hydrate of the cerium compound is composed of trivalent cerium and / or tetravalent cerium.   The contamination component adsorbent according to claim 5, wherein a ratio of tetravalent cerium in the cerium is 5 mass% or more.   The contaminant adsorbent according to any one of claims 1 to 6, wherein the adsorbent further contains an inorganic material containing silica and aluminum.   The contaminant adsorbent according to any one of claims 1 to 7, wherein the content of iron hydroxide in the adsorbent is 5 to 90 mass%.   The contaminant adsorbent according to any one of claims 1 to 8, wherein a content of the hydrate of the cerium compound in the adsorbent is 10 to 95 mass%.   10. The contamination component is at least one component selected from the group consisting of arsenic, fluorine, boron, lead, cadmium, mercury, antimony, chromium, molybdenum, selenium, phosphorus, thallium, indium and bismuth. 5. The contaminant adsorbent according to any one of the above.   A step of adding and mixing a cerium compound hydrate to a predetermined aqueous iron chloride solution to obtain a mixed solution, and adding and mixing an alkaline material into the mixed solution at a predetermined rate to form a suspension, and A step of precipitating iron hydroxide on or near the surface of the hydrate of cerium compound in the suspension by adjusting the pH of the liquid to a range of 7 to 11, and the cerium compound hydrate and iron hydroxide A method for producing a contaminant adsorbent, comprising the step of obtaining an adsorbent having the following.   The method for producing a contaminant adsorbent according to claim 11, further comprising a step of adding and mixing an inorganic material containing silica and aluminum in the mixed solution.   The method for producing a contaminated component adsorbent according to claim 11 or 12, further comprising a step of dehydrating the suspension in order to adjust a moisture content of the adsorbent.   The method for producing a contaminant adsorbent according to any one of claims 11 to 13, wherein the cerium compound hydrate is a cerium hydroxide compound or a cerium oxide compound.   The method for producing a contaminant adsorbent according to any one of claims 11 to 14, wherein the suspension is dehydrated by a filter press method.   The cerium constituting the hydrate of the cerium compound is composed of trivalent cerium and tetravalent cerium, and the ratio of tetravalent cerium in cerium is 5% by mass or more. A method for producing a contaminant adsorbent according to item 1.   The method for producing a contaminated component adsorbent according to any one of claims 11 to 16, wherein the adsorbent is dried at a temperature of 400 ° C or lower to form a powder.

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