阅读说明：本技术 一种双氧水异相催化氧化废水中cod的催化剂的制备方法 (Preparation method of catalyst for heterogeneous catalytic oxidation of COD in wastewater by hydrogen peroxide ) 是由 张昭良 郑德超 辛颖 李倩 薛俊强 杜家伟 张星星 于 2019-04-08 设计创作，主要内容包括：本发明涉及废水高级氧化处理技术领域,特别涉及一种双氧水异相催化氧化废水中COD的催化剂的制备方法,先将Zn盐和Fe(acac)3溶于甲醇、将2-甲基咪唑溶于甲醇,然后将两者混合均匀后装入不锈钢反应釜,通过溶剂热反应得到Fe(acac)3原位包覆在ZIF-8笼内的产物,记为Fe(acac)3@ZIF-8,其在惰性气体下高温碳化,冷却后得到Fe-ZIF-8(NPC)样品。本发明的有益效果是：将废水中的有机物催化氧化为二氧化碳和水,使Fe的利用率最大化,并且显著提高了催化活性,COD去除率显著提高。(The invention relates to the technical field of advanced oxidation treatment of wastewater, in particular to a preparation method of a catalyst for hydrogen peroxide heterogeneous catalytic oxidation of COD in wastewater, which comprises the steps of dissolving Zn salt and Fe (acac)3 in methanol, dissolving 2-methylimidazole in methanol, uniformly mixing the two, then putting the two into a stainless steel reaction kettle, obtaining a product of Fe (acac)3 in-situ coated in a ZIF-8 cage through solvothermal reaction, marking as Fe (acac)3@ ZIF-8, carbonizing the product at high temperature under inert gas, and cooling to obtain an Fe-ZIF-8(NPC) sample. The invention has the beneficial effects that: the organic matters in the wastewater are catalytically oxidized into carbon dioxide and water, so that the utilization rate of Fe is maximized, the catalytic activity is obviously improved, and the removal rate of COD is obviously improved.)

1. A preparation method of a catalyst for heterogeneous catalytic oxidation of COD in wastewater by hydrogen peroxide is characterized by mainly comprising the following steps:

(1) weighing 1-3 g of Zn salt and 0.1-2 g of ferric acetylacetonate (Fe (acac)3) by mass, dissolving in 10-50 mL of methanol, and performing ultrasonic dissolution for 10-60 min to obtain a solution A; weighing 1-3 g of 2-methylimidazole by mass, dissolving in 10-20 mL of methanol, and stirring at normal temperature for 30min to fully stir and dissolve to obtain a solution B;

(2) mixing and stirring the solution A and the solution B for 1 hour, pouring the mixture into a 100mL stainless steel reaction kettle, and placing the stainless steel reaction kettle in an air-blast drying oven, wherein the temperature of the air-blast drying oven is 100-120 ℃, and the solvothermal time is 4-6 hours;

(3) washing a product obtained by solvothermal treatment with DMF (dimethyl formamide) and methanol to neutrality in sequence, and drying a washed sample at 60-80 ℃ overnight in vacuum to obtain an Fe (acac)[email protected] ZIF-8 sample;

(4) and (3) carrying out high-temperature carbonization treatment on the obtained Fe (acac)[email protected] ZIF-8 sample: firstly, pouring a uniformly ground sample into a porcelain boat, placing the porcelain boat in a vacuum high-temperature tube furnace, vacuumizing, introducing inert gas to clean a pipeline, performing heat treatment, and cooling to obtain a Fe-ZIF-8(NPC) sample.

2. The method for preparing the catalyst for heterogeneous catalytic oxidation of COD in the wastewater by hydrogen peroxide according to claim 1, wherein the inert gas is one of nitrogen, argon and helium.

3. The preparation method of the catalyst for heterogeneous catalytic oxidation of COD in wastewater by hydrogen peroxide according to claim 1, characterized in that the conditions of the heat treatment are as follows: the heating rate is 2-5 ℃ min < -1 >, the temperature is 700-900 ℃, the heat preservation is carried out for 3-6 h, and the gas flow is 40-60 mL min < -1 >.

4. The method for preparing the catalyst for heterogeneous catalytic oxidation of COD in wastewater by hydrogen peroxide according to claim 1, wherein the Zn salt is one of zinc sulfate, zinc nitrate and zinc chloride.

5. The method for preparing the catalyst for heterogeneous catalytic oxidation of COD in wastewater by hydrogen peroxide according to claim 1, wherein the Fe-ZIF-8(NPC) sample is applied to wastewater treatment, and can catalytically oxidize organic matters in wastewater into carbon dioxide and water, thereby achieving the purpose of reducing COD in wastewater.

Technical Field

The invention relates to the technical field of advanced oxidation treatment of wastewater, in particular to a preparation method of a catalyst for heterogeneous catalytic oxidation of COD in wastewater by hydrogen peroxide.

Background

Chemical Oxygen Demand (COD) is a pollution index strictly controlled by the state, and the emission standard is becoming stricter. The hydrogen peroxide homogeneous oxidation treatment of wastewater, namely the Fenton reagent method, can effectively degrade COD which is difficult to treat, but can generate a large amount of sludge, thereby bringing difficulty to subsequent advanced treatment. Heterogeneous catalytic oxidation, i.e. using a solid catalyst, avoids this problem, but highly active catalysts are still not completely solved.

Metal Organic Framework compounds (also called MOFs) are crystalline porous materials with periodic network structures formed by connecting inorganic Metal centers (Metal ions or Metal clusters) and bridged Organic ligands through self-assembly. The zeolite imidazolate framework material ZIF-8 is used as one of MOFs, and has the performances of permanent pores, high surface area, open metal sites, excellent water stability and the like. The porous carbon material prepared by calcining the MOFs as the sacrificial template has high specific surface area basically consistent with the precursor, rich pore structure, good chemical stability and adjustable morphology, and can be used as a high-efficiency catalyst or a catalyst carrier for a plurality of important reactions. The single-atom iron is loaded on ZIF-8, so that the catalytic activity of the iron can be greatly improved. In the process of catalyzing the decomposition of the hydrogen peroxide, the monatomic iron supplies electrons to the hydrogen peroxide, hydroxyl radicals decomposed from the hydrogen peroxide are catalyzed to react with organic matters, and meanwhile, the carrier carbon supplies electrons to the monatomic iron to regenerate the catalyst, so that a cycle in the process of catalytic oxidation is completed.

Disclosure of Invention

The invention provides a preparation method of a catalyst for heterogeneous catalytic oxidation of COD in wastewater by hydrogen peroxide, aiming at solving the problems of low hydrogen peroxide utilization rate and low catalytic efficiency in the catalytic oxidation of COD in wastewater by hydrogen peroxide.

The technical scheme of the invention is as follows:

a preparation method of a catalyst for heterogeneous catalytic oxidation of COD in wastewater by hydrogen peroxide mainly comprises the following steps:

(1) weighing 1-3 g of Zn salt and 0.1-2 g of ferric acetylacetonate (Fe (acac)3) by mass, dissolving in 10-50 mL of methanol, and performing ultrasonic dissolution for 10-60 min to obtain a solution A; weighing 1-3 g of 2-methylimidazole by mass, dissolving in 10-20 mL of methanol, and stirring at normal temperature for 30min to fully stir and dissolve to obtain a solution B;

(2) mixing and stirring the solution A and the solution B for 1 hour, pouring the mixture into a 100mL stainless steel reaction kettle, and placing the stainless steel reaction kettle in an air-blast drying oven, wherein the temperature of the air-blast drying oven is 100-120 ℃, and the solvothermal time is 4-6 hours;

(3) washing a product obtained by solvothermal treatment with DMF (dimethyl formamide) and methanol to neutrality in sequence, and drying a washed sample at 60-80 ℃ overnight in vacuum to obtain an Fe (acac)[email protected] ZIF-8 sample;

(4) and (3) carrying out high-temperature carbonization treatment on the obtained Fe (acac)[email protected] ZIF-8 sample: firstly, pouring a uniformly ground sample into a porcelain boat, placing the porcelain boat in a vacuum high-temperature tube furnace, vacuumizing, introducing inert gas to clean a pipeline, performing heat treatment, and cooling to obtain a Fe-ZIF-8(NPC) sample.

Further, the inert gas is one of nitrogen, argon and helium.

The conditions of the heat treatment are as follows: the heating rate is 2-5 ℃ min < -1 >, the temperature is 700-900 ℃, the heat preservation is carried out for 3-6 h, and the gas flow is 40-60 mL min < -1 >.

Furthermore, the Zn salt is one of zinc sulfate, zinc nitrate and zinc chloride.

The Fe-ZIF-8(NPC) catalyst is applied to COD in hydrogen peroxide heterogeneous catalytic oxidation wastewater, wherein Fe can supply electrons to hydrogen peroxide to catalyze the hydrogen peroxide to decompose into hydroxyl radicals with stronger oxidability, then the hydroxyl radicals and organic matters in the wastewater generate oxidation reaction to convert the organic matters into nontoxic carbon dioxide and water, carbon on a carrier supplies the electrons to Fe, and the catalyst is regenerated. Thereby achieving the purpose of reducing COD in the wastewater.

The technical scheme provided by the invention has the beneficial effects that:

the ZIF-8 derived nitrogen-doped porous carbon (Fe-ZIF-8(NPC)) loaded with the monatomic Fe is used for the first time for heterogeneous catalytic oxidation of COD in the wastewater by hydrogen peroxide, and organic matters in the wastewater are catalytically oxidized into carbon dioxide and water, so that the aim of reducing the COD in the wastewater is fulfilled, the utilization rate of Fe is maximized, the catalytic activity is obviously improved, and the removal rate of the COD is obviously improved.

Drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings needed to be used in the description of the embodiments will be briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without creative efforts.

FIG. 1 is a XRD test spectrum of example 1 of the present invention and comparative examples 1, 2 and 3.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, embodiments of the present invention will be described in detail with reference to the accompanying drawings.