Wastewater treatment process for removing cyanide in sewage by utilizing Fenton reaction mechanism

Abstract

The invention discloses a wastewater treatment process for removing cyanide in sewage by utilizing a Fenton reaction mechanism, and belongs to the technical field of water treatment. The process comprises the following steps: adjusting the cyanogen-containing wastewater to be alkaline, then adding a modified ferrous catalyst, and carrying out a Fenton reaction. The process provided by the invention aims to effectively remove the cyanide in the sewage, and by optimizing the reaction conditions and using the catalyst, the process provided by the invention can realize that the cyanide removal rate reaches 90% or above, and has good economical efficiency and environmental friendliness. The method is suitable for industrial sewage treatment, and is especially suitable for treatment of cyanide-containing wastewater generated in metal smelting and chemical industries.

Description

TECHNICAL FIELD

[0001] The application relates to a wastewater treatment process for removing cyanide in wastewater by using a Fenton reaction mechanism, and belongs to the technical field of water treatment. BACKGROUND

[0002] Cyanide is a highly toxic pollutant that widely exists in industrial wastewater, especially in the processes of metal smelting, plastic manufacturing and pesticide production. Traditional treatment methods such as physical adsorption and biological degradation often fail to effectively remove cyanide and may cause secondary pollution. Therefore, it is particularly important to develop an efficient, economical and environmentally friendly cyanide removal technology.

[0003] The Fenton reaction is a kind of advanced oxidation process based on hydrogen peroxide (H2O2) and ferrous ions (Fe 2+ ), which can generate hydroxyl radicals (·OH) under acidic conditions, has strong oxidizing properties and can effectively degrade various organic pollutants, including cyanide. However, under acidic conditions, cyanide will volatilize as hydrogen cyanide (HCN), which is a highly toxic gas that can cause fatal consequences if inhaled. SUMMARY

[0004] To solve the problem of volatilization of toxic gas under acidic conditions in the prior art for treating cyanide-containing wastewater by using the Fenton reaction, the application provides a technical solution for treating cyanide-containing wastewater by using the Fenton reaction under alkaline conditions. By selecting reasonable reaction conditions and catalysts, the problem of volatilization of toxic gas is overcome, and the removal efficiency of cyanide is also improved.

[0005] The application adopts the following technical solution:

[0006] According to the first aspect of the application, a wastewater treatment process for removing cyanide in wastewater by using the Fenton reaction mechanism is provided, characterized in that it comprises the following steps:

[0007] The cyanide-containing wastewater is adjusted to alkaline, and then a modified ferrous catalyst is added for Fenton reaction.

[0008] Optionally, the conditions for adjusting the cyanide-containing wastewater to alkaline include adding an alkali solution to the cyanide-containing wastewater to adjust the pH value of the cyanide-containing wastewater to 7-12. The alkali solution is not strictly limited, for example, it can be a sodium hydroxide solution.

[0009] The process of the application is carried out in an alkaline environment with a pH value of 7-12 to improve the solubility and reactivity of cyanide, inhibit the volatilization of cyanide and avoid poisoning of the operator.

[0010] Optionally, the conditions for the Fenton reaction include a reaction temperature of 1-99℃.

[0011] The reaction temperature in the conditions of the Fenton reaction is preferably 4-99°C to improve the reaction rate while avoiding catalyst deactivation caused by excessively high temperature.

[0012] The traditional Fenton reaction needs to be carried out under acidic conditions with pH 2-4, and the present application creatively raises the reaction pH to the alkaline range of 7-12 while maintaining high temperature conditions (1-99°C), breaking through the traditional technical restrictions.

[0013] The reaction time in the conditions of the Fenton reaction is determined according to the initial concentration of cyanide and the target final concentration, for example, the reaction time can be set to 1-999 minutes.

[0014] Optionally, the flow rate ratio of wastewater to hydrogen peroxide solution added during the Fenton reaction is 100:1, and the concentration of the hydrogen peroxide solution is 4-8%.

[0015] Optionally, the cyanide concentration in the cyanide-containing wastewater is 50-200 mg / L.

[0016] The cyanide concentration in the cyanide-containing wastewater is selected from any value or range value between any two of 50 mg / L, 100 mg / L, 150 mg / L, and 200 mg / L.

[0017] Optionally, the amount of modified ferrous catalyst added is 0.3-0.7 g / L.

[0018] This amount allows it to maintain optimal catalytic efficiency during the reaction process, avoiding precipitation and secondary pollution caused by excessive use of catalyst.

[0019] Optionally, the modified ferrous catalyst is a Fe-Cu-Mn ternary composite catalyst prepared by sol-gel method.

[0020] The specific surface area of the Fe-Cu-Mn ternary composite catalyst is ≥200 m 2 / g.

[0021] The present application uses a modified ferrous catalyst, which improves the reaction activity and stability of ferrous ions by surface modification.

[0022] Optionally, the preparation steps of the Fe-Cu-Mn ternary composite catalyst include:

[0023] A complexing agent is added to an aqueous solution containing ferric nitrate, copper nitrate, and manganese nitrate, a gel reaction is carried out, and the reaction product is filtered, dried, and calcined to obtain the Fe-Cu-Mn ternary composite catalyst.

[0024] Optionally, the molar ratio of ferric nitrate to copper nitrate and manganese nitrate is 7:2:1.

[0025] The ratio of metal ions to water in the aqueous solution is 9 mol:1000-10000 mL;

[0026] The molar ratio of the complexing agent to the metal ions in the aqueous solution is 1.2:1.

[0027] Optionally, the gel reaction conditions include: stirring at 50-70° C. for 2-4 hours;

[0028] The calcination process comprises calcining at 450-550° C. for 2-4 hours.

[0029] The beneficial effects of this application include:

[0030] This application provides a wastewater treatment process for removing cyanide from wastewater using the Fenton reaction mechanism. It can efficiently remove cyanide from wastewater, achieving a removal rate exceeding 90%. By optimizing the reaction conditions, catalyst, and hydrogen peroxide, this process is economical and environmentally friendly, making it suitable for industrial wastewater treatment. The widespread application of this technology will provide an effective solution for the management of cyanide pollution and promote the development of environmental protection. DETAILED DESCRIPTION

[0031] The present application is described in detail below with reference to embodiments, but the present application is not limited to these embodiments.

[0032] Unless otherwise specified, the raw materials in the examples of this application were purchased through commercial channels.

[0033] Unless otherwise specified, conventional methods were used for testing, and instrument settings were those recommended by the manufacturer.

[0034] Example 1 Preparation of multi-metal co-doped catalyst

[0035] Prepared by sol-gel method: iron nitrate, copper nitrate and manganese nitrate are weighed and mixed according to the molar ratio of Fe, Cu and Mn elements of 7:2:1, and then citric acid complexing agent is added (the molar ratio of metal ions to citric acid is 1:1.2), and stirred in a water bath at 60°C for 2 hours to obtain a sol, which is dried at 120°C to obtain a gel, which is then calcined at 500°C for 3 hours to obtain an Fe-Cu-Mn ternary composite catalyst, i.e., a modified ferrous catalyst.

[0036] Physical adsorption experiments have shown that the Fe-Cu-Mn ternary composite catalyst is a mesoporous material with a specific surface area of ​​≥200m 2 / g).

[0037] Example 2 Wastewater Treatment Process for Removing Cyanide from Sewage Using the Fenton Reaction Mechanism

[0038] The pH value of the cyanide-containing wastewater sample (cyanide concentration of 100 mg / L) was adjusted to 7-9 using sodium hydroxide solution, and then the Fe-Cu-Mn ternary composite catalyst prepared in Example 1 (input amount of 0.5 g / L) was added thereto, and the mixture was thoroughly stirred. Then, the reaction was carried out at 45° C. After the reaction started, hydrogen peroxide solution was added to the wastewater (flow rate ratio of 100:1). The concentration of the hydrogen peroxide solution was 5%. Samples were taken regularly during the reaction, and the cyanide concentration was determined according to the national standard method (HJ484-2009).

[0039] The results showed that after 90 minutes of reaction, the cyanide removal rate reached 92%, meeting the requirements for industrial wastewater treatment.

[0040] Each reaction lasted 90 minutes, and the reaction was circulated 15 times. The results showed that the cyanide removal rate reached more than 90%, meeting the requirements for industrial wastewater treatment.

[0041] Comparative Example 1

[0042] The wastewater treatment process for removing cyanide in sewage by utilizing the Fenton reaction mechanism is the same as that in Example 2, except that the catalyst used is the conventional Fe 2+ The catalyst (prepared with reference to the patent publication number 103877978B, specifically the zirconium aluminum composite oxide carrier-2 prepared in Example 2 thereof, iron nitrate, copper nitrate, and manganese nitrate were weighed according to the molar ratio of Fe, Cu, and Mn elements of 7:2:1 to prepare a mixed solution, and the carrier-2 was impregnated in equal volume in the solution, impregnated overnight at room temperature, dried at 110°C for 3h, and then calcined at 400°C for 3h to obtain the conventional Fe2 + catalyst).

[0043] The results showed that after 90 minutes of reaction, the cyanide removal rate reached 45%.

[0044] Each reaction time was 90 minutes, and the reaction was circulated 15 times. The results showed that the cyanide removal rate reached 40%.

[0045] It can be seen that compared with the traditional Fe2 + The catalyst has a significantly improved catalytic efficiency and can maintain 90% activity after being recycled 15 times.

[0046] Example 3

[0047] The wastewater treatment process for removing cyanide in sewage using the Fenton reaction mechanism is the same as that in Example 2, except that the cyanide concentration of the cyanide-containing wastewater sample is 50 mg / L.

[0048] The results showed that after 90 minutes of reaction, the cyanide removal rate reached 80%, meeting the requirements for industrial wastewater treatment.

[0049] Example 4

[0050] The wastewater treatment process for removing cyanide in sewage using the Fenton reaction mechanism is the same as that in Example 2, except that the cyanide concentration of the cyanide-containing wastewater sample is 150 mg / L.

[0051] The results showed that after 90 minutes of reaction, the cyanide removal rate reached 90%, meeting the requirements for industrial wastewater treatment.

[0052] Example 5

[0053] The wastewater treatment process for removing cyanide in sewage using the Fenton reaction mechanism is the same as that in Example 2, except that the cyanide concentration of the cyanide-containing wastewater sample is 200 mg / L.

[0054] The results showed that after 90 minutes of reaction, the cyanide removal rate reached 95%, meeting the requirements for industrial wastewater treatment.

[0055] In summary, it can be seen that the process of the present application shows good removal effect at different cyanide concentrations.

[0056] The above descriptions are merely a few embodiments of the present application and do not constitute any form of limitation to the present application. Although the present application discloses the preferred embodiments as above, they are not intended to limit the present application. Any technical personnel familiar with the present profession, without departing from the scope of the technical solution of the present application, using the technical content disclosed above to make slight changes or modifications are equivalent to equivalent implementation cases and fall within the scope of the technical solution.

Claims

1. A wastewater treatment process for removing cyanide in sewage using the Fenton reaction mechanism, characterized in that: The steps include: The cyanide-containing wastewater is adjusted to alkaline, and then a modified ferrous catalyst is added to carry out the Fenton reaction.

2. The wastewater treatment process for removing cyanide in sewage by utilizing the Fenton reaction mechanism according to claim 1, characterized in that: The conditions for adjusting the cyanide-containing wastewater to alkaline include: adding alkaline solution to the cyanide-containing wastewater to adjust the pH value of the cyanide-containing wastewater to 7-12.

3. The wastewater treatment process for removing cyanide in sewage by utilizing the Fenton reaction mechanism according to claim 1, characterized in that: The conditions of the Fenton reaction include: a reaction temperature of 1 to 99°C.

4. The wastewater treatment process for removing cyanide in sewage by utilizing the Fenton reaction mechanism according to claim 1, characterized in that: During the Fenton reaction, the flow rate ratio of wastewater to the added hydrogen peroxide solution is 100:1, and the concentration of the hydrogen peroxide solution is 4-8%.

5. The wastewater treatment process for removing cyanide in sewage by utilizing the Fenton reaction mechanism according to claim 1, characterized in that: The cyanide concentration in the cyanide-containing wastewater is 50 to 200 mg / L.

6. The wastewater treatment process for removing cyanide in sewage by utilizing the Fenton reaction mechanism according to claim 1, characterized in that: The input amount of the modified ferrous catalyst is 0.3-0.7 g / L.

7. The wastewater treatment process for removing cyanide in sewage by utilizing the Fenton reaction mechanism according to claim 1, characterized in that: The modified ferrous catalyst is a Fe-Cu-Mn ternary composite catalyst prepared by a sol-gel method.

8. The wastewater treatment process for removing cyanide in sewage by utilizing the Fenton reaction mechanism according to claim 7, characterized in that: The preparation steps of the Fe-Cu-Mn ternary composite catalyst include: A complexing agent is added to an aqueous solution containing ferric nitrate, copper nitrate and manganese nitrate to carry out a gel reaction. The reaction product is filtered, dried and calcined to obtain the Fe-Cu-Mn ternary composite catalyst.

9. The wastewater treatment process for removing cyanide in sewage by utilizing the Fenton reaction mechanism according to claim 8, characterized in that: The molar ratio of the ferric nitrate to copper nitrate and manganese nitrate is 7:2:1; The ratio of metal ions to water in the aqueous solution is 9 mol:1000-10000 mL; The molar ratio of the complexing agent to the metal ions in the aqueous solution is 1.2:

1.

10. The wastewater treatment process for removing cyanide in sewage by utilizing the Fenton reaction mechanism according to claim 8, characterized in that: The gel reaction conditions include: stirring at 50-70° C. for 2-4 hours; The calcination process comprises calcining at 450-550° C. for 2-4 hours.