CN101570372A - Method for purifying electroplating wastewater and comprehensively utilizing resources - Google Patents

Abstract

The invention relates to a method for purification of electroplating wastewater and comprehensive utilization of resources, which uses cheap strong base anion exchange resin containing macropores and imidazole structures, and recycles electroplating wastewater based on the coupling technology of chemical redox method, precipitation method and ion exchange method. valuable resources. First, through chemical reaction, Cr(III) is oxidized to Cr(VI) under alkaline conditions, then Zn, Cu, Ni and other heavy metal elements in wastewater are converted into hydroxide precipitation, and finally, strong basic anion resin is used to absorb wastewater The Cr(VI) in the purified water meets the electroplating pollutant discharge standard and reuse requirements, and at the same time, the Cr and other heavy metal resources in the electroplating wastewater can be comprehensively recycled. This method overcomes the defect that acidification is required in the regeneration process of the traditional porous weakly alkaline resin, and has the advantages of simple process, low treatment cost, large treatment capacity and saving acid and alkali consumption. It is a green and environmentally friendly electroplating wastewater treatment method with efficient resource utilization.

Description

A method for purification of electroplating wastewater and comprehensive utilization of resources

technical field

The invention relates to a method for purifying electroplating wastewater and comprehensively utilizing resources.

Background technique

In recent years, my country's electroplating and tanning industry has developed rapidly, and many small and medium-sized enterprises have been established in various places. However, the environmental pollution caused by the waste discharged during the production process is also becoming more and more serious. According to incomplete statistics, the annual discharge of electroplating wastewater in China is about 40×10 ⁸ m ³ , mainly containing Cr(III), Cr(VI), Zn(II), Cu(II), Ni(III), Fe(III ) and other heavy metal ions. Medical research shows that hexavalent chromium is a carcinogen, and the toxicity of Cr(VI) is 100 times greater than that of Cr(III). In wastewater, chromium (VI) exists in the form of CrO ₃ , CrO ₄ ^2- , Cr ₂ O ₇ ^{2- and} so on, depending on the pH value. Due to the high content of harmful substances and complex components, the processing technology is difficult and poses a serious threat to the surrounding environment.

In order to protect the environment and promote the sustainable development of the electroplating industry, the country has formulated the electroplating pollutant discharge standard (GB 21900-2008), which has strict regulations on the discharge of chromium-containing wastewater: from January 1, 2009 to 2010 On June 30, 2008, the maximum allowable emissions of Cr(VI) and total chromium were 0.5mg/L and 1.5mg/L respectively; for new enterprises since August 1, 2008 and for existing enterprises since July 1, 2010 The implementation of the maximum allowable discharge of Cr(VI) and total chromium is 0.2mg/L and 1.0mg/L respectively; in the country where the development density is high, the environmental carrying capacity is weakened or the water environment capacity is small, the ecological environment is fragile, and it is easy to occur In areas where serious water pollution problems require special protection measures, the maximum allowable discharges of Cr(VI) and total chromium are 0.1mg/L and 0.5mg/L, respectively. At the same time, there are strict restrictions on the discharge of other heavy gold elements such as Zn, Cu, and Ni. With the improvement of my country's environmental protection discharge standards, the current discharge of many chromium-containing wastewater far exceeds this regulation, seriously polluting the environment. If chromium and other valuable heavy metal resources can be recovered effectively, it can not only reduce environmental pollution, but also save resources and turn waste into treasure, which has important economic value and social significance.

Commonly used methods for the treatment of electroplating chromium-containing wastewater include chemical precipitation, electrolysis, solvent extraction and ion exchange, each of which has its own advantages and disadvantages. Although the chemical precipitation method is low in cost and widely applicable, it produces a large amount of waste residue and easily causes secondary pollution; the electrolytic reduction method requires simple equipment and occupies a small area, but the electrolysis equipment consumes a lot of energy and the treatment process is cumbersome, so it is not easy to promote; The extraction method has high efficiency, and uses more organic solvents, which is easy to cause secondary pollution; the ion exchange method is currently a relatively advanced method, and the quality of the effluent after treatment is excellent, and the chromium resources can be recycled and utilized, but the one-time investment is large , Operation and management are complex. Liu Zhigang (Chromium Containing Sewage Purification Recovery, Recycling Technology, CN 1810683A) discloses utilization of ion exchange resin and macroporous weak base resin to reclaim chromium resources in chromium-containing wastewater, macroporous weak base resin adsorbs hexavalent chromium in electroplating wastewater, reaching Resource recovery and utilization of hexavalent chromium. Traditionally used to treat electroplating chromium-containing wastewater are macroporous weakly basic anion exchange resins such as D301, D371, and D370. Due to their weak alkalinity, chromium can only be effectively adsorbed under acidic or near-neutral conditions. To achieve high adsorption capacity, the resin must be acidified first, and there are problems of high acid consumption and troublesome operation in the frequent resin regeneration process. The above-mentioned defects in traditional anion exchange resins can be solved by using strong base anion exchange resins containing imidazole structures. Chinese invention patent (Chen Ji, Zhu Lili, Liu Yinghui, a method for adsorbing hexavalent chromium ions in waste water with strong base anion exchange resin containing imidazole structure, patent application number: 200810051262.5) prepared a gel-type strong base anion exchange resin containing imidazole structure The alkali anion exchange resin adsorbs Cr(VI) in wastewater, and no acidification process is required in the regeneration process, which solves the above-mentioned defects of traditional anion exchange resins. However, this gel-type resin has a relatively high production cost, which restricts its large-scale use in ion exchange technology.

Contents of the invention

On the basis of the research on the gel type strong base anion exchange resin containing imidazole structure, the present invention has prepared a cheap macroporous strong base anion exchange resin containing imidazole structure. The resin adsorbs Cr(VI) in electroplating wastewater, and combines chemical redox, precipitation and ion exchange methods to comprehensively recycle Cr(III) and Cr(VI) and other heavy metal resources in electroplating wastewater. Figure 1 is a schematic diagram of the recovery process route for valuable heavy metal resources in electroplating wastewater.

A method for purification of electroplating wastewater and comprehensive utilization of resources provided by the invention, its principle and related reactions are as follows:

(1) Firstly, Cr(III) is oxidized to Cr(VI) under the condition that the pH value of the solution is 13.0-14.0 through a chemical reaction, and then the pH value of the wastewater is adjusted back to 7.0-9.0, so that the Zn, Cu, Valuable heavy metal elements such as Ni, Fe, Al are converted into hydroxide precipitation, and finally the waste water after heavy metal removal is adsorbed with strong basic anion resin to absorb Cr(VI). The purified water quality is required to meet the electroplating pollutant discharge standard and reuse Requirements, while recovering Cr and its heavy metal resources in wastewater. Cr(VI) mainly exists in the form of HCrO ₄ ^- , Cr ₂ O ₄ ^2- , Cr ₂ O ₇ ^2- in wastewater, and the pH value of wastewater controls its existing form. Utilizing the exchange adsorption characteristics of strong basic anion resin to anion, Cr(VI) is adsorbed on the anion exchange resin to be removed, so that the waste water can be purified.

The principle and related reactions of strong base anion exchange resin to adsorb Cr(VI) are as follows:

RCl+HCrO ₄ ^- ＝RHCrO ₄ +Cl ^- (1)

2RCl+CrO ₄ ^2- ＝R ₂ CrO ₄ + ^2Cl- (2)

2RCl+Cr ₂ O ₇ ^2- ＝R ₂ Cr ₂ O ₇ + ^2Cl- (3)

2RCl+2HCrO ₄ ^- ＝R ₂ Cr ₂ O ₇ +2Cl ^- +H ₂ O (4)

After the resin is saturated, it can be regenerated with NaOH+NaCl mixed solution to restore the resin exchange capacity. The principle and related reactions are as follows:

2RHCrO ₄ +2NaOH＝R ₂ CrO ₄ +Na ₂ CrO ₄ +2H ₂ O (5)

R ₂ Cr ₂ O ₇ +2NaOH=R ₂ CrO ₄ +Na ₂ CrO ₄ +H ₂ O (6)

R ₂ CrO ₄ +2NaCl=2RCl+Na ₂ CrO ₄ (7)

A kind of electroplating waste water purification of the present invention, the method for resource comprehensive utilization, its steps and conditions are as follows:

(1) Chromium (III) is oxidized to chromium (VI): import chromium-containing wastewater into the pretreatment tank, first use inorganic alkali to adjust the pH value of the wastewater to 13.0-14.0, and then add oxidant, Cr(III): the mole of oxidant The ratio is 1:1~3, so that the chromium (III) in the wastewater is completely oxidized to chromium (VI);

Described inorganic base is sodium hydroxide, potassium hydroxide or calcium hydroxide;

Described oxidizing agent is hydrogen peroxide or sodium peroxide;

(2) Recovery of valuable heavy metal resources: the wastewater treated in step (1) in the pretreatment pool of step (1) is adjusted to a pH value of 7.0 to 9.0 with inorganic acid, so that zinc, copper, nickel, iron or The aluminum heavy metal elements are converted into hydroxide precipitates, and then filtered, and the filter residue is dehydrated, crushed, and ground to obtain mixed heavy metal raw materials, and a single heavy metal material is further prepared through a hydrometallurgical process;

Described mineral acid is hydrochloric acid, sulfuric acid or nitric acid;

(3) strong basic anion exchange resin adsorption chromium (VI) and resin regeneration: strong basic anion exchange resin is loaded into the adsorption column, the filtrate in the step (2) is adjusted to a pH value of 4.0～6.0 with mineral acid, and then automatically It is introduced into the adsorption column from top to bottom. When the concentration of chromium (VI) in the tail liquid is greater than 0.1 mg/L after the first adsorption column is adsorbed, the second adsorption column is connected in series. When the chromium (VI) concentration in the tail liquid of the second adsorption column is ) concentration is greater than 0.1mg/L, the third adsorption column is connected in series for adsorption, and the first adsorption column is rinsed and regenerated at the same time; when the concentration of chromium (VI) in the tail liquid of the third adsorption column is greater than 0.1mg/L, The first adsorption column is adsorbed, and the second adsorption column is rinsed and regenerated at the same time; when the concentration of chromium (VI) in the tail liquid of the first adsorption column is greater than 0.1mg/L, the second adsorption column is connected in series for adsorption, and the third adsorption column is rinsed at the same time Regeneration; carry out the above-mentioned adsorption and regeneration method in such a cycle operation; stop until the concentration of chromium (VI) in the tail liquid is less than 0.1mg/L;

Described mineral acid is hydrochloric acid, sulfuric acid or nitric acid;

The conditions for the leaching regeneration of the adsorption column are: the eluent is a mixed aqueous solution of sodium hydroxide and sodium chloride with a molar ratio of 1:1, and the molar concentration of sodium hydroxide and sodium chloride is 0.1 to 1.0 mol/L, The eluent is introduced into the adsorption column from top to bottom to rinse and regenerate the adsorption column. When the resin turns from black or yellow to white, it is the regeneration end point, and sodium chromate solution is obtained;

The above-mentioned multiple columns are used in series, and the adsorption and regeneration methods are cyclically operated to fully ensure that the concentration of chromium (VI) in the water after adsorption is less than 0.1mg/L, and at the same time, the ion exchange resin can reach the maximum adsorption capacity.

(4) Preparation of chromium product: the sodium chromate solution is desodiumized by H ⁺ type cation exchange resin to prepare chromic acid or chromic anhydride; adopt soluble barium salt or lead salt precipitation method to prepare barium chromate or lead chromate product; The soluble barium salt is preferably barium chloride, barium carbonate or barium sulfide, and the soluble lead salt is preferably lead acetate, lead nitrate or lead sulfate.

According to the market demand for chromium products, different types of chromium products can be prepared.

The strongly basic anion exchange resin of described step (3) is macroporous imidazole structure anion exchange resin, and its structure is:

In the formula, X ^- is a chloride ion, a sulfate ion or a nitrate ion;

The steps of the preparation method of described macroporous imidazole structure-containing anion exchange resin are as follows:

Stir the chloromethylated styrene type macroporous adsorption resin in N,N-dimethylformamide solvent at room temperature for 2h, then add N-methylimidazole, chloromethylated styrene type macroporous adsorption resin: The molar ratio of N-methylimidazole is 1:1~1.3, react at 40~80°C for 24~72h, filter the synthetic resin and wash it with ethanol, dry the resin in vacuum after washing, and obtain a strong base with a chlorine-type macroporous imidazole structure Anion exchange resin (abbreviated as macroporous RCl);

Stir the chlorine type macroporous strong base anion exchange resin containing imidazole structure in deionized water for 2h, then add sodium sulfate, the chlorine type macroporous strong base anion exchange resin containing imidazole structure: sodium sulfate molar ratio is 1: 0.5～1 , mixed and oscillated for 10 to 24 hours until the reaction is complete, and the resin is filtered, and then the filtered resin is washed with deionized water to remove excess sulfate ions to obtain a sulfate-type macroporous strong base anion exchange resin containing imidazole structure (abbreviated is macroporous R ₂ SO ₄ );

Stir the chlorine-type macroporous strong base anion exchange resin containing imidazole structure in deionized water for 2 hours, then add sodium nitrate chemical reactant with a molar ratio of 1:1 to 1.5, mix and shake for 10 to 24 hours until the reaction is complete, and filter resin, and then wash the filtered resin with deionized water to remove excess nitrate ions to obtain a nitrate-type macroporous imidazole-containing strong base anion exchange resin (abbreviated as macroporous RNO ₃ ).

Because the gel-type strong base anion exchange resin containing imidazole structure and the macroporous strong base anion exchange resin containing imidazole structure prepared by the present invention have the same functional group structure, the adsorption capacity, adsorption optimum conditions, and service life performance of the two resins are different very close. Figure 2 shows the effect of oscillation time on the adsorption capacity of different resins. It can be seen from the figure that the macroporous RCl resin and D301 resin have similar adsorption rates, and the adsorption rate of RCl resin is the fastest, which is mainly related to the particle size of the resin material. Therefore, compared with the adsorption performance, service life and regeneration process of the resin, the anion exchange resin with a macroporous imidazole structure has great advantages, and is expected to replace the traditional weakly basic anion resin in the treatment of Cr(VI) in electroplating wastewater , to realize the technological innovation of ion exchange technology to treat electroplating wastewater.

Beneficial effects: (1) The method for purification of electroplating wastewater and comprehensive utilization of resources provided by the present invention adopts macroporous strong base anion exchange resin containing imidazole structure to adsorb Cr(VI) in electroplating wastewater, which overcomes commercialization of D301, The regeneration process of macroporous weakly basic anion exchange resins such as D371 and D370 needs to consume a large amount of acid, which provides a new and efficient adsorption material and separation technology for the efficient recovery and utilization of chromium in electroplating wastewater.

(2) A method for purification of electroplating wastewater and comprehensive utilization of resources provided by the present invention uses coupling technologies such as chemical oxidation, ion exchange and precipitation to efficiently recycle valuable heavy metal resources such as Cr, Ni, and Cu in electroplating wastewater, It has significant economic and social benefits.

(3) a kind of electroplating waste water purification provided by the present invention, the method for comprehensive resource utilization, adopt the strong alkali anion exchange resin of the macroporous imidazole-containing structure of high thermal stability, mechanical strength and oxidation resistance to continuously absorb Cr in electroplating waste water (VI), which has the advantages of stable process and low processing cost.

Description of drawings

Figure 1 is a schematic diagram of the recovery process route for valuable heavy metal resources in electroplating wastewater.

Figure 2 is a graph showing the influence of oscillation time on the adsorption capacity of different resins.

Fig. 3 is an adsorption and desorption curve diagram of an adsorption resin column.

Detailed ways

Example 1

Take 50g of chloromethylated styrene-type macroporous adsorption resin in a three-necked flask, add 300mL of N,N-dimethylformamide, stir at room temperature for 2h, add 16.5g of N-methylimidazole at 40°C for 72h, filter The resin was synthesized and washed with ethanol. The washed resin is vacuum-dried to obtain a chlorine-type macroporous strong base anion exchange resin containing an imidazole structure.

Stir 1 g of chlorine-type macroporous strong base anion exchange resin containing imidazole structure in deionized water for 2 h, then add 20 mL of sodium sulfate solution with a molar concentration of 2 mol/L and shake for 10 h until the reaction is complete, filter the resin, and then use deionized The filtered resin is washed with water to remove excess sulfate ions to obtain a sulfate-type macroporous strong base anion exchange resin containing an imidazole structure.

Stir 1 g of chlorine-type macroporous strong base anion exchange resin containing imidazole structure in deionized water for 2 hours, then add 20 mL of sodium nitrate solution with a molar concentration of 2 mol/L and shake for 10 hours until the reaction is complete, filter the resin, and then use deionized The filtered resin is washed with water to remove excess nitrate ions to obtain a nitrate type macroporous strong base anion exchange resin containing imidazole structure.

Example 2

Taking the wastewater of an electroplating factory as the research object, the test results of the main components are shown in Table 1. It can be seen from the table that the wastewater contains a large amount of Cr(III), Cr(VI) and other valuable heavy metal elements, and direct discharge causes environmental pollution. Pollution, recovery of valuable heavy metal elements can produce certain economic benefits.

Table 1 Main components of electroplating chromium-containing wastewater

Pollutant name Cr(V) Cr(total) Cu Zn Ni Fe Al Concentration (mg/L) 250 344 28.92 16.61 8.589 134.6 5.063

Chromium (III) is oxidized to chromium (VI): Take 2L of chromium-containing wastewater, use NaOH to adjust the pH value of the wastewater to 13.00, and then add 10.8 mmol of hydrogen peroxide to oxidize the chromium (III) in the wastewater to chromium (VI).

Recovery of valuable heavy metal resources: Use sulfuric acid to adjust the pH value of the wastewater in the pretreatment pool of step (1) to 7.00, so that the zinc, copper, nickel, iron, and aluminum heavy metal elements in the wastewater are converted into hydroxide precipitates, and then filtered, the filter residue After dehydration, pulverization, and grinding, it is a mixed heavy metal raw material, and a single heavy metal material can be prepared through a hydrometallurgical process. The contents of zinc, copper, nickel, iron and aluminum in the filtrate after precipitation were 1.95mg/L, 0.28mg/L, 4.17mg/L, 1.02mg/L and 0.17mg/L respectively.

Adsorption of chromium (VI) on strongly basic anion exchange resin and regeneration of resin: firstly adjust the pH value of the filtrate in step (2) with sulfuric acid to 4.60, and then introduce it into the adsorption column from top to bottom. When the concentration of chromium (VI) in the tail liquid is greater than 0.1mg/L after the first adsorption column is adsorbed, connect the second adsorption column in series, when the concentration of chromium (VI) in the tail liquid of the second adsorption column is greater than 0.1mg/L , the third adsorption column is connected in series, and the first adsorption column is rinsed and regenerated at the same time. The above two columns are used in series to fully ensure that the concentration of chromium (VI) in the water quality after adsorption is less than 0.1 mg/L, and at the same time make the ion exchange resin reach the maximum adsorption capacity. Lead the mixed eluent of 0.3M sodium hydroxide and 0.3M sodium chloride into the first adsorption column from top to bottom, and regenerate the adsorption column. When the resin turns from black or yellow to white, it is the regeneration end point, and chromic acid is obtained. sodium solution. The above-mentioned adsorption and regeneration method operates in a cycle. Figure 3 is the adsorption and desorption curves of the adsorption resin column, the inner diameter of the adsorption column is 1cm, 2.5g of adsorption resin is added, and the flow rate of adsorption and desorption is controlled at 3mL/min.

Chromium product preparation: sodium chromate solution is desodiumized with H ⁺ type cation exchange resin to prepare chromic acid or chromic anhydride product. Collect the eluate in the above desorption ^step and introduce it into the H ⁺ type cation column from top to bottom. The column is regenerated with 1%-10% sulfuric acid solution. The dilute dichromic acid solution is evaporated and concentrated to obtain chromic acid or chromic anhydride products.

Example 3

According to the method of Example 2, in the step of recovering valuable heavy metal resources such as copper and nickel, the pH value is adjusted to 8.00 with hydrochloric acid, so that heavy metal elements such as zinc, copper, nickel and iron in the wastewater are converted into hydroxide precipitation, and the filtrate after precipitation The contents of zinc, copper, nickel, iron, and aluminum in it are 0.13mg/L, 0.22mg/L, 0.41mg/L, 0.69mg/L, and 0.21mg/L respectively.

The filtrate in the step of adsorbing chromium (VI) on the strongly basic anion exchange resin is adjusted to pH 4.00 with hydrochloric acid. According to Example 2, the secondary adsorption columns are used in series, so that the Cr(VI) content in the wastewater after ion exchange treatment is less than 0.1 mg/L.

In the step of preparing the chromium product, the sodium chromate solution is prepared by a soluble barium chloride precipitation method to prepare the barium chromate product. Collect 100 mL of the eluate in the above-mentioned desorption step, measure the concentration of Cr(VI) in the eluate to be 3234 mg/L, add 1.5 g of barium chloride and stir to make Cr(VI) be converted into barium chromate precipitate, filter and dry A barium chromate product is obtained.

Example 4

According to the method of Example 2, in the step of recovering valuable heavy metal resources such as copper and nickel, the pH value is adjusted to 9.00 with nitric acid, so that heavy metal elements such as zinc, copper, nickel and iron in the wastewater are converted into hydroxide precipitation, and the filtrate after precipitation The contents of zinc, copper, nickel, iron, and aluminum in it are 0.06mg/L, 0.17mg/L, 0.32mg/L, 0.32mg/L, and 0.19mg/L, respectively.

The filtrate in the step of adsorbing chromium (VI) on the strongly basic anion exchange resin is adjusted to a pH value of 6.00 with nitric acid. According to Example 2, the secondary adsorption columns are used in series, so that the Cr(VI) content in the wastewater after ion exchange treatment is less than 0.1 mg/L.

In the step of preparing the chromium product, the sodium chromate solution is prepared by a soluble lead acetate precipitation method to prepare the lead chromate product. Collect the eluent 100mL in the above-mentioned desorption step, measure the concentration of Cr(VI) in the eluent to be 3234mg/L, add 2.8g lead acetate and stir to make Cr(VI) be converted into lead chromate precipitate, filter, dry to obtain chromium lead acid products.

Claims (1)

1, the method for a kind of purifying electroplating wastewater, comprehensive utilization of resources is characterized in that, its step and condition are as follows: its step and condition are as follows:

(1) chromium (III) is oxidized to chromium (VI): chromate waste water is imported in the pre-treatment pond, the pH value of at first using mineral alkali to regulate waste water is 13.0～14.0, add oxygenant then, Cr (III): the chemical reaction mol ratio of oxygenant is 1: 1～3, and making chromium (III) complete oxidation in the waste water is chromium (VI);

Described mineral alkali is sodium hydroxide, potassium hydroxide or calcium hydroxide;

Described oxygenant is hydrogen peroxide or sodium peroxide;

(2) recovery has the valency heavy metal resources: the inorganic acid for adjusting pH value of water reuse that the process step (1) in step (1) the pre-treatment pond was handled is 7.0～9.0, make zinc in the waste water, copper, nickel, iron or aluminium huge sum of money element be converted into precipitation of hydroxide, filter then, filter residue is through dehydration, pulverize, grind, obtain the mixture-metal raw material, further prepare single heavy metal material by hydrometallurgical processes;

Described mineral acid is hydrochloric acid, sulfuric acid or nitric acid;

(3) strongly basic anion exchange resin absorption chromium (VI) and resin regeneration: the strongly basic anion exchange resin of packing in the adsorption column, is 4.0～6.0 with the filtrate in the step (2) with inorganic acid for adjusting pH value, import in the adsorption column from top to bottom then, after the absorption of the 1st adsorption column, chromium in the tail washings (VI) concentration is during greater than 0.1mg/L, and the 2nd adsorption column of contacting is when chromium (VI) concentration is greater than 0.1mg/L in the tail washings of the 2nd adsorption column, the 3rd adsorption column of contacting absorption, the 1st adsorption column leaching regeneration simultaneously; When chromium (VI) concentration is greater than 0.1mg/L in the tail washings of the 3rd adsorption column, the 1st adsorption column of contacting absorption, the 2nd adsorption column leaching regeneration simultaneously; When chromium (VI) concentration is greater than 0.1mg/L in the tail washings of the 1st adsorption column, the 2nd adsorption column of contacting absorption, the 3rd adsorption column leaching regeneration simultaneously; So above-mentioned absorption and renovation process are carried out in cyclical operation; Chromium in tail washings (VI) concentration stops less than 0.1mg/L;

Described mineral acid is hydrochloric acid, sulfuric acid or nitric acid;

Described adsorption column leaching regeneration condition is: leacheate is that mol ratio is 1: 1 sodium hydroxide and a sodium-chlor mixed aqueous solution, the concentration of sodium hydroxide and sodium-chlor is respectively 0.1～1.0mol/L, leacheate imports in the adsorption column from top to bottom to the adsorption column leaching regeneration, be the regeneration terminal point when resin is converted into white by black or yellow, obtain chromium acid sodium solution;

(4) preparation chromium product: chromium acid sodium solution is adopted H ⁺The type Zeo-karb takes off sodium, preparation chromic acid or chromic trioxide; Adopt soluble barium salt or lead salt precipitation to prepare baryta yellow or lead chromate product; The preferred bariumchloride of described soluble barium salt, barium carbonate or barium sulphide, the preferred plumbic acetate of solubility lead salt, lead nitrate or lead sulfate;

The strongly basic anion exchange resin of described step (3) is a macropore glyoxaline structure anionite-exchange resin, and its structure is:

In the formula, X ^-Be chlorion, sulfate ion or nitrate ion;

Preparation method's the step that described macropore contains glyoxaline structure anionite-exchange resin is as follows: with the styrene tyle macroporous adsorption resin of chloromethylation at N, stirring at room 2h in the dinethylformamide solvent, add the N-Methylimidazole then, the styrene tyle macroporous adsorption resin of chloromethylation: the mol ratio of N-Methylimidazole is 1: 1～1.3, in 40～80 ℃ of reaction 24～72h, filter synthetic resins and use washing with alcohol, to wash back resin vacuum-drying, obtain the strong anion-exchange resin that chlorine type macropore contains glyoxaline structure;

Chlorine type macropore is contained the strong anion-exchange resin of glyoxaline structure at deionized water for stirring 2h, add sodium sulfate then, chlorine type macropore contains the strong anion-exchange resin of glyoxaline structure: the mol ratio of sodium sulfate is 1: 0.5～1.0, mix vibration 10～24h, until reacting completely, and filter resin, the resin after filtering with deionized water wash again, remove excessive sulfate ion, obtain the strong anion-exchange resin that sulfate radical type macropore contains glyoxaline structure;

Chlorine type macropore is contained the strong anion-exchange resin of glyoxaline structure at deionized water for stirring 2h, add SODIUMNITRATE then, chlorine type macropore contains the strong anion-exchange resin of glyoxaline structure: the mol ratio of SODIUMNITRATE is 1: 1～1.5, mix vibration 10～24h, until reacting completely, and filter resin, the resin after filtering with deionized water wash again, remove excessive nitrate ion, obtain the strong anion-exchange resin that nitrate radical type macropore contains glyoxaline structure.

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