A decoloring agent for color film wastewater and a preparation method thereof

Abstract

The application discloses a kind of decoloring agent for color film wastewater, and 100mL decoloring agent is composed of 10mL ammonia, 30mL complexing agent, 55mL divalent iron salt and hydroxy calcium phosphate aqueous solution and 5mL stabilizer.The application also discloses the preparation method of the above-mentioned decoloring agent for color film wastewater.The basic hydroxy calcium phosphate (HAP) used in the decoloring agent has a large specific surface area, can be well attached with ferrous salt, and the complex formed by ferrous ion, phosphate and other complexes is very close, so it is not easy to fall off, and the ferrous ion loading is high, thereby effectively increasing the removal efficiency of the decoloring agent for color film wastewater on wastewater chroma and COD.

Description

TECHNICAL FIELD

[0001] The present application relates to a kind of color film wastewater decoloring agent, further relates to the preparation method of the above-mentioned decoloring agent. BACKGROUND

[0002] In the production process of TFT-LCD, during the film making process of BM process and RGB process, color film wastewater will be produced in the photoetching, developing and cleaning process on the glass substrate. The color film wastewater carries a large amount of RGB pigment, cleaning agent and photoresist, etc. The RGB dye is azo, bisazo, polyazo and other azo dyes or anthraquinone dyes. The wastewater is black-brown opaque liquid with high SS content and high colority (usually 100-1000 degrees).

[0003] The wastewater decoloring process of colored glass wool product in Chinese patent 202110692915.3 is mainly the method of removing colority by sodium hypochlorite oxidation. Although this method is simple and feasible, and the operation cost is low, residual chlorine will be formed in the oxidation decoloring process, which not only easily leads to sludge floating, but also affects the operation of the subsequent biological system. The colority removal is not good, and the odor is large when adding sodium hypochlorite on site, which affects the on-site environment. Before the subsequent produced water enters the biological system, a reducing agent needs to be added to reduce the ORP potential in the water to a certain extent to reduce its oxidizing property.

[0004] The decoloring method of printing and dyeing wastewater in Chinese patent 201210322887.7 introduces adding adsorbent material for decoloring. This method is simple in adding form and low in cost, but can only remove suspended colority particles in dye wastewater through physical or chemical adsorption. Although it has good removal effect on suspended colority wastewater, it has no removal effect on dissolved organic colority molecules. When treating wastewater containing various forms of colority, the removal of effluent colority is not complete.

[0005] Chinese patent 201410234383.9 discloses an organic-inorganic composite decoloring agent for printing and dyeing wastewater. The decoloring agent uses physical and chemical methods for decoloring, and has good removal effect on colority and COD of printing and dyeing wastewater. However, the preparation of the decoloring agent adds organic matter such as dicyandiamide and polyacrylamide, which has high production cost and is toxic or easy to produce toxic and harmful gas during production, storage and use, causing use limitation.

[0006] In summary, the source of the colority in the color film wastewater is the RGB pigment used in the coating process of the color film engineering of the liquid crystal panel. The pigment is usually azo or anthraquinone dye. The existing treatment scheme is to use sodium hypochlorite or other oxidants to oxidize the RGB pigment, thereby removing the colority. There are also physical or chemical adsorption of colority particles by using adsorption materials (such as activated carbon, natural or modified zeolite, chitosan or chitin), but the chemical treatment method has the problems of incomplete decolorization, large amount of added chemicals, large amount of sludge formed and poor precipitation effect. At the same time, the sodium hypochlorite oxidation method affects the operation of the later biological system. The physical treatment method has the problems of easy agglomeration of the adsorption material, uneven distribution in the wastewater, easy resolubilization of the colority after standing and the like. SUMMARY

[0007] The purpose of the present application is to provide a color film wastewater decolorizing agent which can greatly reduce the colority of the color film wastewater effluent and has good precipitation separation effect. Another purpose of the present application is to provide a preparation method of the color film wastewater decolorizing agent.

[0008] Technical solution: The color film wastewater decolorizing agent provided by the present application is composed of 10 mL of ammonia water, 30 mL of complexing agent, 55 mL of aqueous solution of divalent iron salt and hydroxyapatite, and 5 mL of stabilizer.

[0009] The divalent iron salt is ferrous chloride tetrahydrate, and the purity of the ferrous chloride tetrahydrate powder is above 95% and the mesh number is above 100. The ferrous chloride tetrahydrate powder is of industrial purity, and the content of ferrous chloride is above 99%.

[0010] The hydroxyapatite has a purity of above 96% and a mesh number of above 125 after mechanical grinding, and the crystal structure is hexagonal or monoclinic.

[0011] The aqueous solution of the divalent iron salt and hydroxyapatite is prepared by adding 20 g of ferrous chloride tetrahydrate and 8 g of hydroxyapatite powder into 100 mL of water.

[0012] The complexing agent is prepared by mixing an EDTA aqueous solution with a mass fraction of 20-30% and ammonia water with a mass fraction of 20% at a volume ratio of 2:1. The complexing agent participates in the complexation reaction, the dilute ammonia water provides a weak alkaline environment to prevent the oxidation of ferrous ions, and at the same time increases the surface tension to make the nanoparticles uniformly dispersed.

[0013] The stabilizer is a diammonium hydrogen phosphate solution with a concentration of 0.1-1 mol / L.

[0014] The mass fraction of the ammonia water is 20%.

[0015] The preparation method of the color film wastewater decolorizing agent comprises the following steps:

[0016] (1) The molar ratio of Fe 2+ : Ca 2+ = 1.254-1.256: 1 is added to the ball mill with calcium hydroxyl phosphate coarse powder and ferrous chloride tetrahydrate powder, after mechanical ball milling, the milled powder is collected in the container;

[0017] (2) The formula amount of water is added to the above mixed powder to obtain a divalent iron salt and calcium hydroxyl phosphate aqueous solution, then the formula amount of complexing agent and ammonia water is added to make the mixed solution weakly alkaline; after stirring for 5-15 minutes, solution A is obtained by standing; in the alkaline environment, Fe 2+ is inhibited from being oxidized to Fe 3+ ; at the same time, ammonia water can also prevent the aggregation of fine nanoparticles, making them more uniformly dispersed;

[0018] (3) The formula amount of stabilizer is slowly added to solution A, and the solution is oscillated at 20-30°C for 2-4h using an ultrasonic oscillator to form a dispersed iron / calcium hydroxyl phosphate complex solution B under the action of the complexing agent; ferrous ions replace calcium ions;

[0019] (4) After standing for 2-4h, the upper clear solution of the iron / calcium hydroxyl phosphate complex solution B is removed to obtain a decolorizing agent stock solution C; when used, the decolorizing agent stock solution C is diluted to a working solution with a mass fraction of 10%. After standing, there will be a stratification phenomenon in the upper layer of the solution, and a small part of the clear solution in the upper layer needs to be removed, and the remaining well-dispersed suspension is left as the effective component of the decolorizing agent.

[0020] In step (1), the rotation speed of the ball mill is 500-600 r / min, and the particle size after grinding is 0.075-0.15 mm; the material of the ball mill tank is one of stainless steel, tungsten carbide or zirconia; the material of the ball is steel ball or ceramic ball.

[0021] In step (2), solution A is obtained by standing after stirring at 100 rpm / min for 5-15 minutes.

[0022] The iron / calcium hydroxyl phosphate complex is formed by combining the ferrous ion nano (through grinding, particles collide and cut each other during the grinding process to form a large number of nano particles) calcium hydroxyl phosphate and the complex under the ultrasonic environment, and the system forms a Fenton-like reaction system after being put into water. In this system, the molecular oxygen in the water is in-situ activated to ·O2 (hydroxyl radical, superoxide radical) in water, and the iron / calcium hydroxyl phosphate complex forms a surface oxygen vacancy (oxygen defect), which produces O2- through double electron transfer, and water and oxygen react with Fe 2+The hydroxyl radicals are generated under the in-situ electron transfer of the HAP complex; the HAP plays a skeleton role to prevent the ferrous ions from falling off too early after being complexed, so as to form a ligand with the complex to activate the molecular oxygen. In the activation reaction, the Fe in the iron / hydroxyapatite complex is converted into the superoxide anion radical O2- by the electron transfer mechanism of the surface oxygen vacancy, the free radical is converted into the hydroxyl radical under the action of hydrogen ions, and the hydroxyl radical has high oxidizability. Under a specific pH condition, the Fe 2+ After falling off from the HAP skeleton into the wastewater, the pH of the solution is adjusted (becomes acidic, the Fe 2+ is oxidized into Fe 3+ , and a coagulation and precipitation reaction is generated to remove a large amount of suspended impurities and part of the organic matters through adsorption and sweeping.

[0023] Beneficial effects: Compared with the prior art, the present application has the following remarkable effects: (1) The basic hydroxyapatite (HAP) used in the decoloring agent has a large specific surface area, can be well attached to the ferrous salt, and makes the complex formed by the ferrous ions and the phosphate and other complexes very close and not easy to fall off, so as to effectively increase the removal efficiency of the decoloring agent of the present application on the colority and COD in the wastewater; (2) The hydroxyapatite has a high specific surface area, and can greatly increase the number of active sites of the attached Fe 2+ on the surface. The molecular oxygen is catalyzed and electron-transferred by the HAP-Fe (hydroxyapatite / iron complex) to form the superoxide radical, the superoxide radical reacts with water to generate the hydroxyl radical, and a large amount of the generated hydroxyl radical has a good degradation effect on the azo and anthraquinone substances in the color film wastewater; (3) The Fenton-like reaction makes the color substances in the water form a co-precipitate with the iron hydroxide after the oxidation reaction, and are not easy to be dissolved back into the water, so as to increase the stability of the decoloring effect; that is, the complex of iron forms the trivalent iron free ion after the reaction is completed, the pH of the solution is adjusted to neutral or weak alkaline, the floc of the iron hydroxide is formed, the floc of the iron hydroxide plays an adsorption and bridging role on other suspended substances, so as to precipitate the color suspended particles together; (4) After the reaction of the decoloring agent is completed, the oxidation-reduction potential in the water does not fluctuate greatly, and is non-toxic to the microorganisms, so as to make the subsequent biological treatment more stably run. BRIEF DESCRIPTION OF DRAWINGS

[0024] Figure 1 It is a structural schematic diagram of the iron / hydroxyapatite complex formed after the ferrous ion-loaded nano-hydroxyapatite is combined with the complex;

[0025] Figure 2 It is a flowchart of the decoloring process of the present application. DETAILED DESCRIPTION

[0026] Example 1

[0027] A TFT-LCD panel production enterprise color film wastewater quality: pH 9-10.5, TSS 500-800 mg / L, COD 600-1100 mg / L, TDS 300-500 mg / L, color 50-100 degrees, fluoride ion concentration 15-20 mg / L, discharge 5500 m 3 / d, the wastewater after collection into the raw water pool; as Figure 1 shown, the decolorization process includes the following steps:

[0028] Step 1: adjust the pH of the collected color film wastewater to 7.5-8.5 in the pH adjustment tank, reaction time 15-20 min; into the reaction tank;

[0029] Step 2: the decoloring agent stock solution is diluted to a working solution with a mass fraction of 10%, the working solution is added to the reaction tank, the flow rate of the working solution is 229 L / h, the coagulation reaction time is 15-20 min, and after the reaction, it is added to the flocculation tank;

[0030] Step 3: add PAM (polyacrylamide) flocculant to the flocculation tank, the flow rate of the PAM flocculant is 0.8 L / h, the flocculation reaction time is 30 min, and then it is added to the high-efficiency sedimentation tank;

[0031] Step 4: after entering the high-efficiency sedimentation tank, sediment for 30-45 min, the surface hydraulic load of the sedimentation tank is controlled at 2.5-3.5 m 3 / m 2 ·h;

[0032] Step 5: the supernatant water tank is provided with an on-line pH monitor, and when the pH is greater than 8.5, hydrochloric acid or sulfuric acid is added to control the pH to 7-8;

[0033] Step 6: the effluent from the clean water tank is directly discharged or sent to the next process.

[0034] The colority, COD and fluoride ion concentration data of the effluent from the clean water tank of the decolorization process of Example 1 are shown in Table 1.

[0035] Table 1

[0036] Item raw water after decolorization decolorization rate COD removal rate fluorine removal rate colority 80 4 95％ COD (mg / L) 610 78 87.2％ F (mg / L) 12 7.8 35％

[0037] The formula of the decoloring agent stock solution used in the decoloring process of Example 1 is as follows: 100 mL of the decoloring agent stock solution is composed of 10 mL of ammonia water, 30 mL of complexing agent, 55 mL of aqueous solution of divalent iron salt and hydroxyl calcium phosphate, and 5 mL of stabilizer; the aqueous solution of divalent iron salt and hydroxyl calcium phosphate is prepared by adding 20 g of ferrous chloride tetrahydrate and 8 g of hydroxyl calcium phosphate powder into 100 mL of water; the complexing agent is prepared by mixing 30% EDTA aqueous solution and 20% ammonia water with a volume ratio of 2:1; the stabilizer is 0.5 mol / L diammonium hydrogen phosphate solution; and the mass fraction of the ammonia water is 20%.

[0038] The preparation method of the above decoloring agent stock solution comprises the following steps:

[0039] (1) adding hydroxyl calcium phosphate coarse powder and ferrous chloride tetrahydrate powder into a ball mill according to the molar ratio of Fe 2+ : Ca 2+ = 1.254-1.256:1, collecting the milled powder in a container after mechanical ball milling;

[0040] (2) adding the formula amount of deionized water into the above mixed powder to obtain the aqueous solution of divalent iron salt and hydroxyl calcium phosphate, and then adding the formula amount of complexing agent and ammonia water into the aqueous solution to make the pH value of the mixed solution be weak alkaline (9.5); stirring at a speed of 100 rpm / min for 15 minutes, and then standing to obtain solution A;

[0041] (3) slowly adding the formula amount of stabilizer into solution A, oscillating at 25°C for 2 h by using an ultrasonic oscillator, and forming dispersed iron / hydroxyl calcium phosphate complex solution B under the action of the complexing agent;

[0042] (4) standing iron / hydroxyl calcium phosphate complex solution B for 2 h, and then removing the upper clear solution to obtain decoloring agent stock solution C.

[0043] As shown in Table 1, the decoloring agent of the present application can also combine with fluoride ions in water to form harder and less soluble hydroxyl calcium fluoride, so as to remove low-concentration fluoride ions in wastewater.

[0044] Comparative Example 1

[0045] The decoloring process of Comparative Example 1 is completely identical with that of Example 1, the only difference between Comparative Example 1 and Example 1 is that no stabilizer is added in the formula of the decoloring agent stock solution used in the decoloring process of Comparative Example 1, i.e. 100 mL of the decoloring agent stock solution is composed of 10 mL of ammonia water, 30 mL of complexing agent, 55 mL of aqueous solution of divalent iron salt and hydroxy calcium phosphate and 5 mL of deionized water; the aqueous solution of divalent iron salt and hydroxy calcium phosphate is prepared by adding 20 g of ferrous chloride tetrahydrate and 8 g of hydroxy calcium phosphate powder into 100 mL of water; the complexing agent is prepared by mixing 30% by mass of EDTA aqueous solution and 20% by mass of ammonia water in a volume ratio of 2:1; the mass fraction of ammonia water is 20%.

[0046] The data of colority, COD and fluorine ion concentration of the water out of and into the water tank in the decoloring process of Comparative Example 1 are shown in Table 2.

[0047] Table 2

[0048] Item raw water after decolorization decolorization rate COD removal rate fluorine removal rate colority 80 22 72.5％ COD (mg / L) 610 156 74.7％ F (mg / L) 12 9.5 20.8％

[0049] The decoloring agent of Comparative Example 1 has poor decoloring effect, because the hydroxy calcium phosphate reacts with hydrogen ions in water during complexing after no stabilizer is added, which greatly reduces the number of active sites.

[0050] Example 2

[0051] A TFT-LCD production enterprise, the water quality of the color film organic wastewater of the enterprise is as follows: drainage volume 7300 m 3 / d, pH 9-10.5, COD 1000-1400 mg / L, TSS 300-500 mg / L, TDS 300-500 mg / L, colority 50-100 degrees, fluorine ion concentration 10-15 mg / L, the wastewater is collected and then enters the raw water tank; the decoloring process comprises the following steps:

[0052] First step: the collected color film wastewater is adjusted to pH 7.5-8.5 in the pH adjusting tank, and the reaction time is 15-20 min; and then enters the reaction tank;

[0053] Second step: the decoloring agent stock solution is diluted into working solution with a mass fraction of 10%, the decoloring agent working solution is added into the reaction tank, the flow rate of the decoloring agent working solution is 3.3 L / min, the coagulation reaction time is 15-20 min, and then enters the flocculation tank after reaction;

[0054] Third step: PAM flocculant is added into the flocculation tank, the flow rate of the PAM flocculant is 1.2 L / h, the flocculation reaction time is 30 min, and then enters the high-efficiency sedimentation tank;

[0055] Step 4: After entering the high-efficiency sedimentation tank, it settles for 30 to 45 minutes. The hydraulic load on the surface of the sedimentation tank is controlled at 2.5 to 3.5 m 3 / m 2 ·h;

[0056] Step 5: A pH online monitor is installed in the supernatant water tank. When the pH is greater than 8.5, hydrochloric acid or sulfuric acid is added to control the pH at 7-8.

[0057] Step 6: The water from the clean water tank is discharged directly or enters the next process.

[0058] The decolorizing agent used in the decolorization process of Example 2 is the same as that in Example 1.

[0059] Example 2 Decolorization process The chromaticity, COD and fluoride ion concentration data of the effluent and influent of the clear water tank are shown in Table 3.

[0060] Table 3

[0061] Item raw water after decolorization decolorization rate COD removal rate fluorine removal rate colority 85 4 95.3％ COD (mg / L) 1200 165 86.25％ F (mg / L) 12 7.1 40.83％

[0062] Comparative Example 2

[0063] The decolorization process of Comparative Example 2 is exactly the same as that of Example 2. The only difference between Comparative Example 2 and Example 2 is that the decolorizer stock solution used in the decolorization process of Comparative Example 2 does not contain a complexing agent. That is, 100 mL of the decolorizer stock solution is composed of 10 mL of ammonia water, 55 mL of an aqueous solution of a divalent iron salt and calcium hydroxyphosphate, 5 mL of a stabilizer, and 30 mL of deionized water; the aqueous solution of the divalent iron salt and calcium hydroxyphosphate is prepared by adding 20 g of ferrous chloride tetrahydrate and 8 g of calcium hydroxyphosphate powder to 100 mL of water; the stabilizer is a diammonium hydrogen phosphate solution with a concentration of 0.5 mol / L; and the mass fraction of ammonia water is 20%.

[0064] Comparative Example 2 The chromaticity, COD and fluoride ion concentration data of the effluent and influent of the decolorization process clear water tank are shown in Table 4.

[0065] Table 4

[0066] Item raw water after decolorization decolorization rate COD removal rate fluorine removal rate colority 85 55 35.3％ COD (mg / L) 1200 670 44.2％ F (mg / L) 12 7.1 40.83％

[0067] The decolorization effect of the decolorizer in Comparative Example 2 becomes very poor. The reason is that when no complexing agent is added, calcium hydroxyphosphate cannot form a ligand with iron, and cannot produce a Fenton-like reaction to produce highly oxidizing free radicals. It only relies on the redox property of ferrous chloride to perform decolorization, and its decolorization effect is very poor.

[0068] Comparative Example 3: Using sodium hypochlorite as a decolorizing agent

[0069] A TFT-LCD manufacturer, the water quality of the color film organic wastewater of this enterprise is: discharge volume 7300m 3pH 9-10.5, COD 1000-1400 mg / L, TSS 300-500 mg / L, TDS 300-500 mg / L, color 50-100 degrees, fluoride concentration 10-20 mg / L; the decolorization process comprises the following steps:

[0070] First step: adjust the pH of the collected color film wastewater to 7.5-8.5, reaction time 15-30 min; then add sodium hypochlorite with a mass concentration of 12% into the oxidation decolorization tank, maintain ORP > 400 mV, reaction time 30-45 min, the effluent enters the reaction tank;

[0071] Second step: add polyaluminum chloride with a mass concentration of 30% into the reaction tank, flow rate 10 L / min, coagulation reaction 60 min, then add PAM, reaction 30 min, enter the sedimentation tank; the hydraulic retention time of the sedimentation tank is 3 h, the supernatant enters the intermediate water tank, the hydraulic retention time of the intermediate water tank is 2 h;

[0072] Third step: the effluent from the intermediate tank enters the pH adjustment tank, reaction time 15 min, pH adjustment to 6.5-7.5; then add sodium bisulfite (mass percentage 10%), make ORP < 250 mV, and then enter the clear water tank.

[0073] The color and COD data of the effluent and influent of the clear water tank in the decolorization process of Comparative Example 3 are shown in Table 5.

[0074] Table 5

[0075] Item raw water after decolorization decolorization rate 85 85 COD removal rate 4 16 fluorine removal rate 95.3 81.2％ colority 1200 1200 COD (mg / L) 165 272 F (mg / L) 86.25％ 77.33％ Item Example 2 sodium hypochlorite comparative example

[0076] As can be seen from the comparison between Example 2 and Comparative Example 3, the effluent color of Example 2 is 2-4 degrees, the decolorization effect is excellent, and since the decolorizing agent is HAP / Fe complex, a Fenton-like reaction is generated to make the color in the water undergo oxidation reaction and form co-precipitation with iron hydroxide, the precipitation effect is excellent, and there is no floating sludge problem; in addition, the reaction process of Example 2 does not increase the oxidation-reduction potential in the water, so there is no need to add additional reducing agents such as sodium bisulfite for reduction, saving cost, and not affecting the operation of the subsequent biological treatment system.

[0077] Comparative Example 4

[0078] The decolorization process of Comparative Example 4 is completely consistent with that of Example 2, and the only difference between Comparative Example 4 and Example 2 is that the HAP in the decolorizing agent used in the decolorization process of Comparative Example 2 is changed to a shell activated carbon with a larger specific surface area. Specifically, 100 mL of the decolorizing agent stock solution is composed of 10 mL of ammonia water, 30 mL of a complexing agent, 55 mL of an aqueous solution of a divalent iron salt and hydroxyapatite, and 5 mL of a stabilizing agent; the aqueous solution of the divalent iron salt and hydroxyapatite is prepared by adding 20 g of ferrous chloride tetrahydrate and 8 g of shell activated carbon powder to 100 mL of water; the complexing agent is prepared by mixing an aqueous solution of EDTA with a mass fraction of 30% and ammonia water with a mass fraction of 20% at a volume ratio of 2:1; the stabilizing agent is a diammonium hydrogen phosphate solution with a concentration of 0.5 mol / L; and the mass fraction of the ammonia water is 20%.

[0079] The colority and COD data of the effluent and influent of the water tank in the decolorization process of Comparative Example 4 are shown in Table 6.

[0080] Table 6

[0081] raw water colority treated water colority colority removal rate 85 raw water COD 30 treated water COD 64.7％ COD removal rate 1200 effluent ORP 292 100 mv 75.67％

[0082] As can be seen from the comparison between Example 2 and Comparative Example 4, the colority removal rate of the decolorizing agent with a hydroxyapatite powder skeleton is 30% higher than that of Comparative Example 4 using shell activated carbon, because the decolorizing agent of the present application can form an iron complex and form a Fenton-like reaction in use to produce free radicals with higher oxidation to react with color substances to degrade and thus decolorize, while the activated carbon decolorization with a larger specific surface area is based on physical adsorption, and the adsorption capacity of the activated carbon powder is limited, and the decolorization efficiency for color film wastewater is low.

[0083] 240 mv (with reducing agent) Item Comparative Example 3 raw water colority treated water colority colority removal rate (%) raw water COD treated water COD COD removal rate Figure 1 The structure of the iron / hydroxyapatite complex formed by the combination of the ferrous ion-loaded nanometer hydroxyapatite and the complex is shown in the figure, in which the brown small balls are Ca 2+ , the red small balls are Fe 2+ , and the blue large balls are PO4 3- phosphate.

Claims

1. A color film wastewater decolorizer, characterized by: 100 mL of a decolorizing agent comprises 10 mL of ammonia water, 30 mL of a complexing agent, 55 mL of an aqueous solution of a divalent iron salt and calcium hydroxyphosphate, and 5 mL of a stabilizer. The aqueous solution of the divalent iron salt and calcium hydroxyphosphate is prepared by adding 20 to 25 g of ferrous chloride tetrahydrate and 8 to 10 g of calcium hydroxyphosphate powder to 100 mL of water. The complexing agent is prepared by mixing an EDTA aqueous solution with a mass fraction of 20 to 30% and an ammonia water with a mass fraction of 20% in a volume ratio of 2:1 to 1.

5. The stabilizer is a diammonium hydrogen phosphate solution with a concentration of 0.1 to 1 mol / L. The mass fraction of the ammonia water is 20 to 30%.

2. The color film wastewater decolorizing agent according to claim 1, characterized in that: The purity of the ferrous chloride tetrahydrate powder is above 95%, and the mesh size is above 100 meshes.

3. The color film wastewater decolorizing agent according to claim 1, characterized in that: The purity of the calcium hydroxyphosphate is above 96%, and the mesh size after mechanical grinding is above 125 meshes.

4. The method for preparing the color film wastewater decolorizing agent according to claim 1, characterized in that: The steps include: (1) Press Fe 2+ :Ca 2+ = =1.254~1.256:1 molar ratio of calcium hydroxyphosphate coarse powder and ferrous chloride tetrahydrate powder are added to the ball mill, after mechanical ball milling, the ground powder is collected in a container; (2) Adding a formulated amount of water to the mixed powder to obtain an aqueous solution of divalent iron salt and calcium hydroxyphosphate, and then adding a formulated amount of complexing agent and ammonia water to the mixed solution to make the mixed solution weakly alkaline; stirring for 5 to 15 minutes and then allowing to stand to obtain solution A; (3) Slowly add the formulated amount of stabilizer to solution A, and oscillate using an ultrasonic oscillator at 20-30°C for 2-4 hours to form a dispersed iron / hydroxy calcium phosphate complex solution B under the action of the complexing agent; (4) After the iron / hydroxy calcium phosphate complex solution B is allowed to stand for 2 to 4 hours, the upper clear solution is removed to obtain the decolorant stock solution C.

5. The method for preparing a color film wastewater decolorizing agent according to claim 4, characterized in that: In step (1), the ball mill rotates at a speed of 500-600 r / min, and the particle size of the particles after grinding is 0.075-0.15 mm.

6. The method for preparing a color film wastewater decolorizing agent according to claim 4, characterized in that: In step (2), the mixture is stirred at a speed of 100 r / min for 5 to 15 minutes and then allowed to stand to obtain solution A.

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