Antimony-removing coagulant, its preparation method and application

Abstract

The present application relates to the technical field of water treatment, and provides a antimony-removing coagulant as well as a preparation method and application thereof.The preparation raw material of the antimony-removing coagulant provided by the present application comprises aluminum foil pickling solution, calcium aluminate powder, ferric chloride and an additive, wherein the additive is inorganic acid.The present application utilizes the aluminum foil pickling solution to provide aluminum chloride, the aluminum chloride and the calcium aluminate powder can react to generate polyaluminum chloride, and the polyaluminum chloride is combined with the ferric chloride to generate polyaluminum ferric chloride which has good flocculation effect; meanwhile, the present application adopts inorganic acid as the additive, so that the coagulant can be flocculated more sensitively, and the stability of the coagulant can be improved, and the effluent water quality can be prevented from being out of standard in terms of colority.Furthermore, the present application adopts the aluminum foil pickling solution as the raw material, so that waste is made from waste, the environment is friendly, the raw material is easy to obtain, the cost is low, and the present application has wide application prospect.

Description

Technical Field

[0001] This invention relates to the field of water treatment technology, and in particular to an antimony removal coagulant, its preparation method, and its application. Background Technology

[0002] In recent years, antimony pollution from the dyeing and printing industry has received widespread attention. Antimony compounds, commonly used catalysts in the production of PET (Potassium Electrolyte), are released into water bodies during the dyeing and printing process, polluting the environment. Furthermore, antimony is a toxic and carcinogenic heavy metal that is easily absorbed by organisms and has been listed as a priority pollutant by the World Health Organization.

[0003] Currently, the main methods for treating antimony-containing wastewater include adsorption, electrochemical methods, membrane treatment, and coagulation sedimentation. Among these, adsorption, electrochemical, and membrane treatment are all relatively expensive, while coagulation sedimentation removes antimony by adding a coagulant to react chemically with the antimony in the wastewater, forming precipitates or flocs. This method is widely used due to its simple process, convenient operation, and high cost-effectiveness.

[0004] Commonly used coagulation and sedimentation agents for antimony removal include iron salts, aluminum salts, and sulfides. Ferric chloride is a traditional iron salt with strong corrosiveness and poor stability. The treated water is prone to having an iron color, and the effluent water color exceeds the standard. Ferrous sulfate has a low antimony removal rate and poor stability. Sulfides also have low antimony removal efficiency and may generate antimony sulfide precipitates during the antimony removal process, causing secondary pollution.

[0005] In summary, there is an urgent need to provide a coagulant with good stability and high antimony removal efficiency. Summary of the Invention

[0006] In view of this, the present invention provides an antimony-removing coagulant, its preparation method, and its application. The antimony-removing coagulant provided by the present invention has good stability, high antimony removal efficiency, and a simple preparation method with readily available raw materials and low cost.

[0007] To achieve the above-mentioned objectives, the present invention provides the following technical solution:

[0008] An antimony-removing coagulant comprises the following raw materials in weight percentage: 30-55% aluminum foil pickling solution, 38.5-65% calcium aluminate powder, 0.1-1.5% ferric chloride, and 1-5% additives;

[0009] The aluminum foil pickling solution comprises hydrochloric acid and aluminum chloride; the aluminum content in the aluminum foil acid is 4-8 wt% based on Al2O3.

[0010] The additive is an inorganic acid.

[0011] Preferably, the antimony-removing coagulant comprises the following raw materials in weight percentage: 35-46% aluminum foil pickling solution, 50-62% calcium aluminate powder, 1-1.5% ferric chloride, and 2-3% additives.

[0012] Preferably, the inorganic acid is sulfuric acid or phosphorous acid; the concentration of the sulfuric acid is 95-98 wt%.

[0013] The present invention also provides a method for preparing the antimony-removing coagulant described above, comprising the following steps:

[0014] Alumina foil acid and calcium aluminate powder are mixed and polymerized to obtain a polymerization reaction solution;

[0015] The polymerization reaction solution and ferric chloride were mixed and compounded to obtain a compound reaction solution;

[0016] The compound reaction solution and the additives are mixed to obtain the antimony removal coagulant.

[0017] Preferably, the polymerization reaction is carried out at a temperature of 75–88°C.

[0018] Preferably, the polymerization reaction takes 1 to 4 hours.

[0019] Preferably, the temperature of the compounding reaction is 75–88°C.

[0020] Preferably, the reaction time is 0.2 to 1 hour.

[0021] Preferably, after the compounding reaction, the resulting reaction solution is filtered, and the resulting filtrate is the antimony-removing coagulant.

[0022] The present invention also provides the application of the antimony-removing coagulant described in the above-described scheme or the antimony-removing coagulant prepared by the preparation method described in the above-described scheme in the treatment of antimony-containing wastewater.

[0023] This invention provides an antimony-removing coagulant, comprising the following raw materials by weight percentage: 30-55% aluminum foil pickling solution, 38.5-65% calcium aluminate powder, 1-1.5% ferric chloride, and 1-5% additives; the aluminum foil pickling solution comprises hydrochloric acid and aluminum chloride; the aluminum content in the aluminum foil acid is 4-8 wt% (calculated as Al2O3); the additives are inorganic acids. This invention utilizes the aluminum foil pickling solution to provide aluminum chloride, which reacts with calcium aluminate powder to generate polyaluminum chloride, which then combines with ferric chloride to generate polyaluminum ferric chloride with good flocculation properties. Simultaneously, the use of inorganic acids as additives makes the coagulant more sensitive to flocculation, achieving good flocculation even under low temperature and low turbidity conditions; furthermore, the additives improve the stability of the coagulant, preventing excessive color in the effluent. Moreover, this invention uses aluminum foil pickling solution as a raw material, achieving waste-to-waste conversion, which is environmentally friendly, uses readily available raw materials, is low-cost, and has broad application prospects.

[0024] The present invention also provides a method for preparing the antimony-removing coagulant described in the above scheme. The preparation method provided by the present invention has simple steps, is easy to operate, and is suitable for large-scale production. Detailed Implementation

[0025] This invention provides an antimony removal coagulant comprising the following raw materials in weight percentage: 30-55% aluminum foil pickling solution, 38.5-65% calcium aluminate powder, 0.1-1.5% ferric chloride, and 1-5% additives;

[0026] The aluminum foil pickling solution comprises hydrochloric acid and aluminum chloride; the aluminum content in the aluminum foil acid is 4-8 wt% based on Al2O3.

[0027] The additive is an inorganic acid.

[0028] Unless otherwise specified, all raw materials / components used in this invention are commercially available.

[0029] The raw materials for preparing the antimony-removing coagulant, by weight percentage, include 35-55% aluminum foil pickling solution, preferably 35-46%, specifically 35%, 40%, or 45%. In this invention, the aluminum foil pickling solution comprises hydrochloric acid and aluminum chloride; based on Al2O3, the aluminum content in the aluminum foil acid is preferably 4-8 wt%, specifically 4 wt%, 5 wt%, 6 wt%, 7 wt%, or 8 wt%; the aluminum foil pickling solution is specifically waste pickling liquid from aluminum foil bags.

[0030] The raw materials for preparing the antimony-removing coagulant, by weight percentage, include 38.5-65% calcium aluminate powder, preferably 50-62%. In this invention, the calcium aluminate powder is used to react with aluminum chloride in the aluminum foil pickling solution to generate polyaluminum chloride.

[0031] The raw materials for preparing the antimony removal coagulant include 0.1-1.5% ferric chloride, preferably 1-1.5%, and specifically 1%, 1.4%, or 1.5%, by weight percentage.

[0032] The raw materials for preparing the antimony-removing coagulant include 1-5% by weight, preferably 2-3% additives. In this invention, the additives are inorganic acids, specifically sulfuric acid or phosphorous acid; the concentration of the sulfuric acid is preferably 95-98 wt%. In this invention, the additives can improve the flocculation sensitivity of the coagulant and also improve its stability.

[0033] The present invention also provides a method for preparing the antimony-removing coagulant described above, comprising the following steps:

[0034] Alumina foil acid and calcium aluminate powder are mixed and polymerized to obtain a polymerization reaction solution;

[0035] The polymerization reaction solution and ferric chloride were mixed and compounded to obtain a compound reaction solution;

[0036] The compound reaction solution and the additives are mixed to obtain the antimony removal coagulant.

[0037] This invention involves mixing aluminum foil acid and calcium aluminate powder for a polymerization reaction to obtain a polymerization reaction solution. In this invention, the polymerization reaction temperature is preferably 75–88°C, more preferably 83–85°C; the polymerization reaction time is preferably 1–4 hours, more preferably 2–3.5 hours. In a specific embodiment of this invention, aluminum foil acid is preferably first added to a reaction vessel, stirred and heated to 75–88°C, and then calcium aluminate powder is slowly added to carry out the polymerization reaction. During the polymerization reaction, aluminum chloride and calcium aluminate powder react to form polyaluminum chloride.

[0038] After the polymerization reaction is completed, the resulting polymerization reaction solution is mixed with ferric chloride for a compounding reaction to obtain a compounding reaction solution. In this invention, the temperature of the compounding reaction is preferably 75–88°C, more preferably 83–85°C; the time of the compounding reaction is preferably 0.2–1 h, more preferably 0.3–0.5 h. In a specific embodiment of this invention, after the polymerization reaction is completed, ferric chloride is preferably added directly to the reaction solution, and the compounding reaction is carried out under stirring conditions. During the compounding reaction, polyaluminum chloride and ferric chloride compound to form polyaluminum ferric chloride.

[0039] In this invention, after the compounding reaction, it is preferable to further filter the resulting reaction solution, and the resulting filtrate is the antimony-removing coagulant. In this invention, the chemical formula of the antimony-removing coagulant is: [Al2(OH)] n Cl 6-n ] m [Fe2(OH) N Cl6-N ] M In the formula, n, m, N, and M are all integers.

[0040] This invention also provides the application of the antimony-removing coagulant described in the above-described scheme or the antimony-removing coagulant prepared by the preparation method described in the above-described scheme in the treatment of antimony-containing wastewater. In this invention, the total antimony content of the antimony-containing wastewater is preferably 0.1-1.5 mg / L, the pH value is preferably 7.5-9, and the turbidity is preferably 1-8 NTU; the dosage of the antimony-removing coagulant is 100-300 ppm.

[0041] The technical solutions of this invention will be clearly and completely described below with reference to the embodiments thereof. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0042] Example 1

[0043] 1.75 tons of aluminum foil acid were added to the reactor and stirred until the temperature reached 85°C. 3.1 tons of calcium aluminate powder were slowly added and the reaction was carried out for 3 hours. 0.05 tons of ferric chloride were added and the mixture was stirred for 0.2 hours. 0.1 tons of phosphorous acid were added, and the mixture was mixed evenly and filtered. The filtrate was the finished antimony removal coagulant.

[0044] Example 2

[0045] 2.25 tons of aluminum foil acid were added to the reactor and stirred until the temperature reached 83°C. 2.53 tons of calcium aluminate powder were slowly added and the reaction was allowed to proceed for 3.5 hours. 0.07 tons of ferric chloride were added and the mixture was stirred for 0.5 hours. 0.15 tons of phosphorous acid were added, and the mixture was stirred until homogeneous. The mixture was then filtered, and the filtrate was the finished antimony removal coagulant.

[0046] Test Example 1

[0047] The wastewater used in this test case was the influent of a wastewater treatment plant in an industrial park. The raw water had a total antimony content of 1.12 mg / L, a pH of 8.14, a turbidity of 6.17, and a color of 30.

[0048] The coagulant was added to the wastewater and stirred rapidly at 250 rpm for 2 min, then stirred slowly at 40 rpm for 20 min, followed by sedimentation for 20 min. The supernatant was then taken for total antimony content and color testing. The coagulant used was the antimony removal coagulant prepared in Example 1 or Example 2. Ferric chloride and polyferric sulfate were used as control experiments. The amount of coagulant added was 100 ppm.

[0049] The test results are shown in Table 1.

[0050] Table 1. Test results of antimony removal effect

[0051]

[0052] As can be seen from the data in Table 1, the antimony removal coagulant prepared in this invention can achieve an antimony removal efficiency of approximately 96%, while the color of the effluent decreases from 30 to 11-12, indicating that the coagulant has good stability. In contrast, when using ferric chloride and polyferric sulfate for antimony removal, the antimony removal efficiency is lower, and the color of the treated effluent increases.

[0053] The antimony removal rate of the antimony removal coagulant of the present invention was tested under low temperature and low turbidity conditions. The results showed that when the turbidity of the antimony-containing wastewater was 1-2 NTU and the water temperature was 2-5℃, the antimony removal coagulant prepared in Examples 1-2 had a turbidity removal rate of 70-90%, while the turbidity removal rate of polyaluminum chloride was only 20-30%.

[0054] Comparative Example 1

[0055] 1.75 tons of aluminum foil acid were added to the reactor, and the mixture was stirred and heated to 85°C. 3.1 tons of calcium aluminate powder were then slowly added, and the reaction was allowed to proceed for 3 hours. 0.05 tons of ferric chloride were then added, and the mixture was stirred for 0.2 hours. The mixture was then filtered, and the filtrate was the antimony removal coagulant product A. The antimony removal effect of product A was tested according to the conditions in Test Example 1, and compared with the coagulant prepared in Example 1. The results are shown in Table 2.

[0056] Table 2. Antimony Removal Effect Test Results

[0057]

[0058] The data in Table 2 shows that the coagulant in Comparative Example 1 omitted the condition of phosphorous acid, and the antimony removal rate of the resulting coagulant decreased, indicating that phosphorous acid can improve the antimony removal rate of the coagulant.

[0059] In addition, the shelf life of the coagulants prepared in Examples 1 and 2 and the coagulant prepared in Comparative Example 1 was tested. The results showed that the viscosity and antimony removal effect of the coagulants prepared in Examples 1 and 2 remained basically unchanged after being placed at room temperature for 180 days, while the viscosity of the coagulant prepared in Comparative Example 1 increased after being placed at room temperature for 90 days, and the antimony removal effect deteriorated significantly. This indicates that the addition of acid can improve the stability of the antimony removal coagulant of the present invention.

[0060] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. Use of antimony-free coagulant in the treatment of wastewater containing antimony, characterized in that, The antimony-removing coagulant is prepared from the following raw materials by weight percentage: aluminum foil pickling solution 30-55%, calcium aluminate powder 38.5-65%, ferric chloride 0.1-1.5%, and auxiliary agent 1-5%; The aluminum foil pickling solution comprises hydrochloric acid and aluminum chloride; the aluminum content in the aluminum foil pickling solution is 4-8% by weight based on Al2O3; the auxiliary agent is an inorganic acid; and the inorganic acid is phosphorous acid; The preparation method of the antimony-removing coagulant comprises the following steps: mixing the aluminum foil pickling solution and the calcium aluminate powder to perform a polymerization reaction, to obtain a polymerization reaction liquid; mixing the polymerization reaction liquid and the ferric chloride to perform a compounding reaction, to obtain a compounding reaction liquid; mixing the compounding reaction liquid and the auxiliary agent, to obtain the antimony-removing coagulant.

2. Use according to claim 1, characterized in that, The antimony-removing coagulant comprises the following raw materials by weight percentage: aluminum foil pickling solution 35-46%, calcium aluminate powder 50-62%, ferric chloride 0.5-1.5%, and auxiliary agent 2-3%.

3. Use according to claim 1, characterized in that, The temperature of the polymerization reaction is 75-88℃.

4. Use according to claim 1 or 3, characterized in that, The time of the polymerization reaction is 1-4h.

5. The use according to claim 1, characterized in that, The temperature of the compounding reaction is 75-88℃.

6. Use according to claim 1 or 5, characterized in that, The time of the compounding reaction is 0.2-1h.

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