Treatment process of p-nitrochlorobenzene production wastewater

Abstract

The invention discloses a p-nitrochlorobenzene production wastewater treatment process, and relates to the technical field of wastewater treatment, the p-nitrochlorobenzene production wastewater treatment process comprises the following steps: S1, filtering p-nitrochlorobenzene production wastewater, and removing suspended solid particles to obtain a preliminary purification liquid; s2, adjusting the pH value of the primary purified liquid to 5-6 in an adjusting tank, then adding a humus / montmorillonite / zinc oxide composite material and persulfate, carrying out ultraviolet irradiation, and stirring for 1-2 hours to obtain oxidized wastewater; and S3, carrying out solid-liquid separation on the oxidized wastewater, and discharging the separated liquid after the separated liquid reaches the qualified standard. By using the humus / montmorillonite / zinc oxide composite material, not only can p-nitrochlorobenzene molecules be specifically adsorbed and enriched, but also p-nitrochlorobenzene can be degraded under the action of zinc oxide and persulfate, so that the degradation rate and the total treatment efficiency are remarkably improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of wastewater treatment, in particular to a treatment process of p-nitrochlorobenzene production wastewater. BACKGROUND

[0002] P-nitrochlorobenzene is a core organic chemical intermediate, which is widely used in the preparation of pesticides, rubber, preservatives and other industrial products. However, this substance has significant harm to human health and ecological environment. Studies have shown that p-nitrochlorobenzene can cause methemoglobinemia and anemia; many studies have also pointed out that it may be a genotoxic and suspected carcinogen, and therefore it is listed as a priority controlled toxic pollutant by the United States Environmental Protection Agency (EPA), the European Union and China, with clear "carcinogenic, teratogenic and mutagenic" effects and genetic toxicity.

[0003] From the molecular structure, p-nitrochlorobenzene contains both nitro and chlorine atoms, both of which are strong electron-withdrawing groups, significantly reducing the electron cloud density of the benzene ring, making the chemical properties of the compound extremely stable and difficult to naturally degrade and persist in the environment. In addition, p-nitrochlorobenzene has strong inhibitory effect on the enzyme system and cell membrane of microorganisms, which can cause the activity of the electron transport system (ETS) to decrease, thereby seriously hindering the growth of microorganisms and the metabolism of organic matter, and thus it is difficult to be effectively degraded by conventional biological methods.

[0004] At present, the treatment of p-nitrochlorobenzene production wastewater still faces technical challenges, and there is a lack of efficient treatment process. For example, physical and chemical adsorption method not only cannot completely remove p-nitrochlorobenzene but also easily causes secondary pollution, so there is an urgent need for a treatment process for efficiently degrading p-nitrochlorobenzene production wastewater. SUMMARY

[0005] The purpose of the present application is to provide a treatment process for p-nitrochlorobenzene production wastewater to efficiently degrade p-nitrochlorobenzene.

[0006] The present application provides a treatment process for p-nitrochlorobenzene production wastewater, comprising the following steps: S1, filtering the p-nitrochlorobenzene production wastewater to remove suspended solid particles, to obtain a preliminary purified liquid; S2, adjusting the pH value of the preliminary purified liquid to 5-6 in a regulating tank, then adding humus / montmorillonite / zinc oxide composite material and persulfate to the tank, and performing ultraviolet irradiation and stirring for 1-2 hours to obtain oxidized wastewater; S3, performing solid-liquid separation on the oxidized wastewater, and discharging the separated liquid after reaching the qualified standard.

[0007] By adopting the technical scheme, firstly, the wastewater containing p-nitrochlorobenzene is filtered to remove suspended solid particles therein, thereby creating good conditions for subsequent treatment; secondly, the pH is adjusted to a weak acid environment of 5-6 to provide optimal reaction conditions for the subsequent oxidation process; finally, the humus / montmorillonite / zinc oxide composite material is used to generate strong oxidizing free radicals under ultraviolet light irradiation, thereby realizing efficient degradation of p-nitrochlorobenzene.

[0008] Specifically, the humus / montmorillonite / zinc oxide composite material has multiple functions, the montmorillonite provides a good carrier structure and adsorption performance; the humus can promote electron transfer and enhance catalytic activity; the zinc oxide generates free-moving electron-hole pairs under ultraviolet light excitation, and cooperates with the persulfate to generate sulfate radicals and hydroxyl radicals. The persulfate is activated under ultraviolet light irradiation and material catalysis to generate strong oxidizing sulfate radicals, which can effectively attack the benzene ring in the molecular structure of p-nitrochlorobenzene to realize ring-opening degradation. In addition, the persulfate can also attack the unsaturated bonds in the humus to generate intermediate products that can initiate the generation of hydroxyl radicals, thereby accelerating the removal rate of p-nitrochlorobenzene.

[0009] Preferably, the humus / montmorillonite / zinc oxide composite material is obtained by the following method: A1, glucose, glycine and catechol are added to deionized water, mixed uniformly, then the pretreated montmorillonite is added, ultrasonic is performed for 8-15h, then filtration, washing and drying are performed to obtain a humus / montmorillonite composite; A2, the humus / montmorillonite composite is dispersed in deionized water, a buffer solution and dopamine are added at the same time, stirring is performed for 30-50h, centrifugal drying is performed to obtain a dopamine / humus / montmorillonite composite; A3, cetyltrimethylammonium bromide and zinc acetate dihydrate are dissolved in ethanol, stirring is performed at 80-90°C for 1-2h, then potassium hydroxide and the dopamine / humus / montmorillonite composite are added, stirring is performed for 6-8h, then filtration and drying are performed.

[0010] By adopting the above technical scheme, firstly, the humus is generated in situ on the montmorillonite, the Maillard reaction and polymerization reaction of glucose, glycine and catechol occur under hydrothermal conditions to form a humus-like structure with rich functional groups; then the polydopamine is formed by polymerization of dopamine under alkaline conditions, the polydopamine can not only be anchored and encapsulated on the surface of the montmorillonite to form a firm organic hybrid layer to prevent the humus from being lost in the subsequent steps or in use, but also the amino and phenolic hydroxyl groups rich in the polydopamine layer can be used as excellent coordination and nucleation sites to effectively capture and stabilize the zinc ions in the solution, guide the uniform and dense growth of zinc oxide nanoparticles and avoid the agglomeration of the zinc oxide nanoparticles; in addition, the benzene ring on the polydopamine molecule can produce a very strong π-π conjugation effect with the benzene ring on the p-nitrochlorobenzene to enrich the pollutants around the catalytically active sites and improve the degradation efficiency of the p-nitrochlorobenzene through the proximity effect. Finally, the zinc oxide nanoparticles are generated in situ by hydrolysis of zinc acetate under alkaline conditions on the dopamine / humus / montmorillonite composite to form the humus / montmorillonite / zinc oxide composite material.

[0011] Preferably, in step A1, the pretreated montmorillonite is prepared by the following method: The dried montmorillonite is dispersed in deionized water, ultrasonic dispersion is performed for 30-60 min, iron chloride is added, stirring, washing and drying are performed to obtain the pretreated montmorillonite.

[0012] Preferably, in step A1, the amount ratio of glucose, glycine, catechol, deionized water and pretreated montmorillonite is 0.01 mol:0.01 mol:0.01 mol:200 mL:(3-5) g.

[0013] Preferably, in step A2, the amount ratio of the humus / montmorillonite composite, deionized water, buffer and dopamine is (3-5) g:100 mL:200 mL:(1-2) g.

[0014] Preferably, in step A2, the buffer is Tris-HCl with a pH value of 8.5.

[0015] Preferably, in step A3, the amount ratio of the dopamine / humus / montmorillonite composite, cetyltrimethylammonium bromide, ethanol, zinc acetate dihydrate and potassium hydroxide is 1 g:(5-6) g:150 mL:(3-4) g:(0.5-1) g.

[0016] Preferably, in step S2, the persulfate salt includes monopersulfate and / or dipersulfate.

[0017] Preferably, in step S2, the amount of the humus / montmorillonite / zinc oxide composite material is 0.01-0.1 Kg / L.

[0018] Preferably, the amount of persulfate used in step S2 is 0.02-0.3 Kg / L.

[0019] Preferably, the wavelength of the ultraviolet light is 365 nm, and the irradiation time is 90-120 min.

[0020] The beneficial effects of the present application are: 1. The present application can not only specifically adsorb and enrich p-nitrochlorobenzene molecules through the strong pi-pi conjugation effect, but also greatly promote the conduction of photo-generated electrons by using humus / montmorillonite / zinc oxide composite materials. The targeted adsorption and in-situ catalysis are organically combined to directly transport the pollutants to the active sites, solve the core problem of low efficiency caused by random collision of free radicals and pollutants, and significantly improve the degradation rate and total treatment efficiency.

[0021] 2. The present application ingeniously couples photocatalysis, persulfate activation and heterogeneous Fenton-like reaction. Zinc oxide generates electron-hole pairs under ultraviolet light; the pre-loaded iron center constitutes a catalytic cycle to continuously activate persulfate; at the same time, persulfate can also attack the unsaturated bonds in humus to generate new free radical precursors, thus creating a stable and high-concentration free radical environment, which not only can efficiently break the stable benzene ring of p-nitrochlorobenzene, but also avoids the disadvantage of easy deactivation of single catalytic path, ensuring the long-term operation stability of the system. DETAILED DESCRIPTION

[0022] In order to make the above-mentioned purposes, features and advantages of the present application more obvious and easy to understand, the specific embodiments of the present application are described in detail below.

[0023] A treatment process for p-nitrochlorobenzene production wastewater, comprising the following steps: S1. Filtering the p-nitrochlorobenzene production wastewater to remove suspended solid particles and obtain a preliminary purified liquid; S2. Adjusting the pH value of the preliminary purified liquid to 5-6 in a conditioning tank, then adding humus / montmorillonite / zinc oxide composite material and persulfate to the tank, and irradiating with ultraviolet light and stirring for 1-2 h to obtain oxidized wastewater; S3. Solid-liquid separating the oxidized wastewater, and discharging the separated liquid after reaching the qualified standard.

[0024] By adopting the above technical solution, the wastewater containing p-nitrochlorobenzene is first filtered to remove suspended solid particles therein, creating good conditions for subsequent treatment; then the pH value is adjusted to 5-6 in a weak acidic environment to provide the best reaction conditions for the subsequent oxidation process; finally, the humus / montmorillonite / zinc oxide composite material cooperates with persulfate to generate strong oxidizing free radicals under ultraviolet light irradiation, realizing efficient degradation of p-nitrochlorobenzene.

[0025] Specifically, the humus / montmorillonite / zinc oxide composite material has multiple functions. Montmorillonite provides good carrier structure and adsorption performance. Humus can promote electron transfer and enhance catalytic activity. Zinc oxide generates photo-generated electron-hole pairs under ultraviolet light excitation, and cooperates with persulfate to generate sulfate radicals and hydroxyl radicals. Persulfate is activated under ultraviolet light irradiation and material catalysis to generate strong oxidizing sulfate radicals, which can effectively attack the benzene ring in the structure of p-nitrochlorobenzene molecules to achieve ring-opening degradation. In addition, persulfate can also attack the unsaturated bond in humus to generate intermediate products that can initiate the generation of hydroxyl radicals, thereby accelerating the removal rate of p-nitrochlorobenzene.

[0026] In some embodiments, the humus / montmorillonite / zinc oxide composite material is obtained by the following method: A1, glucose, glycine and catechol are added to deionized water, mixed uniformly, then the pretreated montmorillonite is added, ultrasonic for 8-15h, then filtered, washed and dried to obtain a humus / montmorillonite composite; A2, the humus / montmorillonite composite is dispersed in deionized water, a buffer solution is added at the same time, dopamine is added and stirred for 30-50h, then centrifuged and dried to obtain a dopamine / humus / montmorillonite composite; A3, cetyltrimethylammonium bromide and zinc acetate dihydrate are dissolved in ethanol, stirred at 80-90°C for 1-2h, then potassium hydroxide and the dopamine / humus / montmorillonite composite are added, stirred for 6-8h, then filtered and dried.

[0027] By adopting the above technical scheme, first, humus is generated in situ on the montmorillonite. Glucose, glycine and catechol undergo Maillard reaction and polymerization reaction under hydrothermal conditions to form a humus-like structure with rich functional groups. Then dopamine is polymerized under alkaline conditions to form polydopamine. The polydopamine not only can be anchored and encapsulated on the surface of the montmorillonite to form a firm organic hybrid layer, preventing the loss of humus in subsequent steps or use, but also the abundant amino and phenolic hydroxyl groups on the polydopamine layer can serve as excellent coordination and nucleation sites, effectively capturing and stabilizing zinc ions in the solution, guiding the uniform and dense growth of zinc oxide nanoparticles and avoiding their agglomeration. In addition, the benzene ring on the polydopamine molecule can produce a very strong π-π conjugation effect with the benzene ring on the p-nitrochlorobenzene, enriching the pollutants around the catalytically active sites and improving the degradation efficiency of p-nitrochlorobenzene through the proximity effect. Finally, zinc oxide nanoparticles are generated in situ on the dopamine / humus / montmorillonite composite by hydrolysis of zinc acetate under alkaline conditions, forming a humus / montmorillonite / zinc oxide composite material.

[0028] In some embodiments, in step A1, the pretreated montmorillonite is prepared by the following method: The dried montmorillonite is dispersed in deionized water, ultrasonic dispersion for 30-60 min, and then iron chloride is added, stirred, washed and dried to obtain the product.

[0029] By using the above technical scheme, more trivalent iron ions are introduced into the interlayer of the montmorillonite, which can improve the efficiency of the subsequent polyphenol-Maillard reaction between glucose, glycine and catechol, so that the in-situ polycondensation is generated on the surface and in the interlayer of the montmorillonite to form a humic-like layer with rich quinone groups and phenolic hydroxyl groups. In addition, the introduction of more trivalent iron ions can be reduced to divalent iron by the subsequent persulfate, and the divalent iron can react with the persulfate to generate sulfate radicals and trivalent iron, thereby realizing the efficient degradation of nitrochlorobenzene.

[0030] In some embodiments, in step A1, the amount ratio of glucose, glycine, catechol, deionized water and pretreated montmorillonite is 0.01 mol: 0.01 mol: 0.01 mol: 200 mL: (3-5) g; humus can be generated by using glucose, glycine and catechol, wherein glucose provides carbon source, glycine provides nitrogen source, and catechol provides phenolic hydroxyl group; the above amount ratio can generate humus on the surface and in the interlayer of the montmorillonite, ensuring sufficient active sites.

[0031] In some embodiments, in step A2, the amount ratio of humus / montmorillonite complex, deionized water, buffer and dopamine is (3-5) g: 100 mL: 200 mL: (1-2) g; this ratio ensures that dopamine can form a complete and uniform polydopamine coating layer on the surface of the humus / montmorillonite complex, while avoiding excessive polymerization of dopamine leading to pore blockage.

[0032] In some embodiments, in step A2, the buffer is Tris-HCl with a pH value of 8.5; this buffer is conducive to the oxidative polymerization of dopamine to form a stable polydopamine layer, while not damaging the structure of the humus / montmorillonite complex.

[0033] In some embodiments, in step A3, the amount ratio of dopamine / humus / montmorillonite complex, cetyltrimethylammonium bromide, ethanol, zinc acetate dihydrate and potassium hydroxide is 1 g: (5-6) g: 150 mL: (3-4) g: (0.5-1) g; zinc oxide nanoparticles are generated by hydrolysis of zinc acetate dihydrate in an alkaline environment, and this ratio can ensure that zinc oxide is uniformly distributed on the surface of the material in the form of nanoparticles, which not only ensures sufficient photocatalytic activity, but also avoids the decrease of activity caused by too large particles.

[0034] In some embodiments, in step S2, the persulfate salt comprises monopersulfate and or diperdodecylbenzenesulfonic acid; the persulfate salt can not only produce strong oxidizing sulfate radicals under the catalysis of ultraviolet light and the material to degrade p-chlorophenol, but also attack the unsaturated bonds in humus to generate intermediate products that can initiate the production of hydroxyl radicals, thereby accelerating the removal rate of p-nitrochlorobenzene.

[0035] In some embodiments, in step S2, the amount of the humus / montmorillonite / zinc oxide composite material is 0.01-0.1 Kg / L; this amount range can ensure the treatment effect while controlling the material cost.

[0036] In some embodiments, in step S2, the amount of the persulfate salt is 0.02-0.3 Kg / L; this amount range can provide sufficient oxidant concentration to ensure the complete degradation of p-nitrochlorobenzene, while avoiding waste of the oxidant and secondary pollution.

[0037] In some embodiments, the wavelength of the ultraviolet light is 365 nm, and the irradiation time is 90-120 min; this wavelength matches the band gap width of zinc oxide, which can effectively excite photo-generated electron-hole pairs, and this irradiation time can ensure sufficient degradation of p-nitrochlorobenzene.

[0038] The specific embodiments of the present application are described in detail below, but it should be understood that the protection scope of the present application is not limited by the specific embodiments.

[0039] Preparation Example

[0040] Preparation Example 1, a humus / montmorillonite / zinc oxide composite material, is obtained by the following method: A1, disperse 1 g of dried montmorillonite in deionized water, ultrasonic dispersion for 60 min, add 0.3 g of ferric chloride, stir, wash, and dry to obtain A2, add 0.01 mol of glucose, 0.01 mol of glycine, and 0.01 mol of catechol to 200 mL of deionized water, mix uniformly, then add 4 g of pretreated montmorillonite, ultrasonic for 15 h, filter, wash, and dry to obtain a humus / montmorillonite composite; A3, disperse 4 g of the humus / montmorillonite composite into 100 mL of deionized water, add 200 mL of Tris-HCl buffer with a pH value of 8.5, and add 1.2 g of dopamine while stirring for 50 h, then centrifuge and dry to obtain a dopamine / humus / montmorillonite composite; A4, dissolve 5.5 g of cetyltrimethylammonium bromide and 4 g of zinc acetate dihydrate in 150 mL of ethanol, stir at 90°C for 1 h, then add 0.7 g of potassium hydroxide and 1 g of the dopamine / humus / montmorillonite composite, stir for 8 h, filter, and dry to obtain a humus / montmorillonite / zinc oxide composite material.

[0041] Preparation Example 2, a humus / montmorillonite / zinc oxide composite material, differs from Preparation Example 1 only in that the montmorillonite is not pretreated with loading of ferric chloride.

[0042] Preparation Example 3, a humus / montmorillonite / zinc oxide composite material, is obtained by the following method: A1, 1 g of dried montmorillonite is dispersed in deionized water, ultrasonic dispersion for 60 min, 0.3 g of ferric chloride is added, stirring, washing, drying to obtain A2, 4 g of pretreated montmorillonite is dispersed in 100 mL of deionized water, 200 mL of Tris-HCl buffer with pH value of 8.5 is added, 1.2 g of dopamine is added and stirred for 50 h, centrifugal drying to obtain dopamine / humus / montmorillonite composite; A3, 5.5 g of cetyltrimethylammonium bromide and 4 g of zinc acetate dihydrate are dissolved in 150 mL of ethanol, after stirring at 90°C for 1 h, 0.7 g of potassium hydroxide and 1 g of dopamine / humus / montmorillonite composite are added, stirring for 8 h, filtering and drying to obtain a humus / montmorillonite / zinc oxide composite material.

[0043] Preparation Example 4, a humus / montmorillonite / zinc oxide composite material, is obtained by the following method: A1, 1 g of dried montmorillonite is dispersed in deionized water, ultrasonic dispersion for 60 min, 0.3 g of ferric chloride is added, stirring, washing, drying to obtain A2, 0.01 mol of glucose, 0.01 mol of glycine and 0.01 mol of catechol are added to 200 mL of deionized water, after mixing evenly, 4 g of pretreated montmorillonite is added, ultrasonic for 15 h, filtering, washing and drying to obtain a humus / montmorillonite composite; A3, 5.5 g of cetyltrimethylammonium bromide and 4 g of zinc acetate dihydrate are dissolved in 150 mL of ethanol, after stirring at 90°C for 1 h, 0.7 g of potassium hydroxide and 1 g of dopamine / humus / montmorillonite composite are added, stirring for 8 h, filtering and drying to obtain a humus / montmorillonite / zinc oxide composite material.

[0044] Preparation Example 5, a humus / montmorillonite / zinc oxide composite material, is obtained by the following method: A1, 1 g of dried montmorillonite is dispersed in deionized water, ultrasonic dispersion for 60 min, 0.3 g of ferric chloride is added, stirring, washing, drying to obtain A2, 0.01 mol glucose, 0.01 mol glycine and 0.01 mol catechol were added into 200 mL deionized water, after mixing evenly, 4 g of pre-treated montmorillonite was added, after ultrasonic for 15 h, filtration, washing and drying, humus / montmorillonite composite was obtained; A3, 4 g of humus / montmorillonite composite was dispersed into 100 mL deionized water, 200 mL Tris-HCl buffer solution with pH value of 8.5 was added, at the same time, 1.2 g dopamine was added, stirring for 50 h, centrifugal drying, dopamine / humus / montmorillonite composite was obtained.

[0045] Example

[0046] Example 1, a treatment process of p-nitrochlorobenzene production wastewater, comprising the following steps: S1, the p-nitrochlorobenzene production wastewater was filtered to remove suspended solid particles, and a preliminary purified liquid was obtained; S2, the preliminary purified liquid was adjusted to pH value of 5 in the adjusting tank by using 1M hydrochloric acid solution, then humus / montmorillonite / zinc oxide composite material prepared in Preparation Example 1 and persulfate were added, and the mixture was irradiated by ultraviolet light with wavelength of 365 nm for 2 h and stirred for 2 h, to obtain oxidized wastewater; S3, the oxidized wastewater was subjected to solid-liquid separation, the separated liquid was discharged after reaching the qualified standard, and the filtrate that did not reach the qualified standard was again introduced into the adjusting tank for treatment; The amount of humus / montmorillonite / zinc oxide composite material was 0.02 Kg / L, and the amount of persulfate was 0.04 Kg / L.

[0047] Example 2, a treatment process of p-nitrochlorobenzene production wastewater, which was different from Example 1 only in that the amount of humus / montmorillonite / zinc oxide composite material was 0.05 Kg / L.

[0048] Comparative Example

[0049] Comparative Example 1, a treatment process of p-nitrochlorobenzene production wastewater, which was different from Example 1 only in that the humus / montmorillonite / zinc oxide composite material prepared in Preparation Example 2 was used to replace the humus / montmorillonite / zinc oxide composite material in Example 1.

[0050] Comparative Example 2, a treatment process of p-nitrochlorobenzene production wastewater, which was different from Example 1 only in that the humus / montmorillonite / zinc oxide composite material prepared in Preparation Example 3 was used to replace the humus / montmorillonite / zinc oxide composite material in Example 1.

[0051] Comparative Example 3, a treatment process for p-nitrochlorobenzene production wastewater, differs from Example 1 only in that the humus / montmorillonite / zinc oxide composite material prepared in Preparation Example 4 is used instead of the humus / montmorillonite / zinc oxide composite material in Example 1.

[0052] Comparative Example 4, a treatment process for p-nitrochlorobenzene production wastewater, differs from Example 1 only in that the humus / montmorillonite / zinc oxide composite material prepared in Preparation Example 5 is used instead of the humus / montmorillonite / zinc oxide composite material in Example 1.

[0053] Performance test

[0054] The treatment processes described in Examples 1-2 and Comparative Examples 1-4 were used to treat p-nitrochlorobenzene wastewater from a chemical plant in Dongzhi County, Anhui Province. The pH of the raw p-nitrochlorobenzene wastewater was 11.6, and the p-nitrochlorobenzene content was 783 mg / L. After treatment, the p-nitrochlorobenzene content of the filtrate was detected, and the results are shown in Table 1. Table 1 Performance test results

[0055] According to Table 1, in combination with Example 1 and Comparative Example 1, it can be seen that the p-nitrochlorobenzene content of Comparative Example 1 is higher than that of Example 1. The reason is that, in Comparative Example 1, the montmorillonite was not pretreated with loaded ferric chloride, so the iron active center of the humus / montmorillonite / zinc oxide composite material was insufficient. This not only reduced the catalytic efficiency of the material for the polyphenol-Maillard reaction between glucose, glycine and o-diphenol, affecting the quality of the humus layer, but more importantly, it was unable to continuously activate persulfate through Fe 3+ / Fe 2+ circulation in the subsequent photocatalytic process, resulting in insufficient generation of sulfate radicals, thereby reducing the degradation efficiency of p-nitrochlorobenzene.

[0056] In combination with Example 1 and Comparative Example 2, it can be seen that the p-nitrochlorobenzene content of Comparative Example 2 is higher than that of Example 1. The reason is that, in Comparative Example 2, the montmorillonite was not in-situ generated humus, so the material lacked the rich functional groups and quinone groups provided by the humus. This was not conducive to the material's ability to promote electron transfer, affected the effective use of photo-generated electrons, and also reduced the sites for attacking unsaturated bonds to generate hydroxyl radical precursors, resulting in poor degradation effect.

[0057] In combination with Example 1 and Comparative Example 3, it can be seen that the content of p-nitrochlorobenzene in Comparative Example 3 is higher than that in Example 1, and the reason is that the montmorillonite in Comparative Example 3 does not load dopamine, so that the strong adsorption site and efficient electron shuttle channel provided by the polydopamine are missing, the pollutant enrichment effect is weakened, the photoelectron transmission is blocked, and the play of the adsorption-catalysis synergistic effect is affected.

[0058] In combination with Example 1 and Comparative Example 4, it can be seen that the content of p-nitrochlorobenzene in Comparative Example 4 is higher than that in Example 1, and the reason is that no zinc oxide is generated on the montmorillonite in Comparative Example 4, so that the photoelectron-hole pairs cannot be generated under ultraviolet light irradiation, which not only leads to the failure of the photocatalytic free radical generation path, but also makes the Fe 3+ / Fe 2+ The driving force of the cycle caused by the photoelectron is insufficient, leading to low activation efficiency of the persulfate, insufficient number of free radicals, and difficulty in effectively degrading p-nitrochlorobenzene.

[0059] The above only discloses several specific embodiments of the present application, but the embodiments of the present application are not limited thereto, and any changes that can be thought of by those skilled in the art shall fall within the protection scope of the present application.

Claims

1. A process for treating wastewater from the production of p-nitrochlorobenzene, characterized in that, The method comprises the following steps: S1, filtering the p-nitrochlorobenzene production wastewater to remove suspended solid particles, to obtain a preliminary purified liquid; S2, adjusting the pH value of the preliminary purified liquid to 5-6 in an adjusting tank, then adding humus / montmorillonite / zinc oxide composite material and persulfate salt to the adjusting tank, and performing ultraviolet irradiation and stirring for 1-2 hours to obtain oxidized wastewater; S3, performing solid-liquid separation on the oxidized wastewater, and discharging the separated liquid after reaching the qualified standard.

2. The treatment process of p-nitrochlorobenzene production wastewater according to claim 1, characterized in that, The humus / montmorillonite / zinc oxide composite material is obtained by the following method: A1, adding glucose, glycine and catechol into deionized water, uniformly mixing, then adding pretreated montmorillonite, ultrasonicating for 8-15 hours, and then filtering, washing and drying to obtain a humus / montmorillonite composite; A2, dispersing the humus / montmorillonite composite into deionized water, adding buffer solution and dopamine while stirring for 30-50 hours, centrifuging and drying to obtain a dopamine / humus / montmorillonite composite; A3, dissolving cetyltrimethylammonium bromide and zinc acetate dihydrate in ethanol, stirring at 80-90°C for 1-2 hours, then adding potassium hydroxide and the dopamine / humus / montmorillonite composite, stirring for 6-8 hours, and then filtering and drying.

3. The treatment process of p-nitrochlorobenzene production wastewater according to claim 2, characterized in that, In step A1, the pretreated montmorillonite is prepared by the following method: Dispersing the dried montmorillonite in deionized water, ultrasonicating for 30-60 minutes, adding ferric chloride, stirring, washing and drying to obtain the pretreated montmorillonite.

4. The treatment process of p-nitrochlorobenzene production wastewater according to claim 2, characterized in that, In step A1, the amount ratio of the glucose, glycine, catechol, deionized water and pretreated montmorillonite is 0.01 mol:0.01 mol:0.01 mol:200 mL:(3-5) g.

5. The treatment process of p-nitrochlorobenzene production wastewater according to claim 2, characterized in that, In step A2, the amount ratio of the humus / montmorillonite composite, deionized water, buffer solution and dopamine is (3-5) g:100 mL:200 mL:(1-2) g.

6. The treatment process of p-nitrochlorobenzene production wastewater according to claim 2, characterized in that, In step A3, the amount ratio of the dopamine / humus / montmorillonite composite, cetyltrimethylammonium bromide, ethanol, zinc acetate dihydrate and potassium hydroxide is 1 g:(5-6) g:150 mL:(3-4) g:(0.5-1) g.

7. The treatment process of p-nitrochlorobenzene production wastewater according to claim 1, characterized in that, In step S2, the persulfate salt includes permonosulfate salt and / or perdisulfate salt.

8. The treatment process of p-nitrochlorobenzene production wastewater according to claim 1, characterized in that, In step S2, the amount of the humus / montmorillonite / zinc oxide composite material is 0.01-0.1 Kg / L.

9. The treatment process of p-nitrochlorobenzene production wastewater according to claim 1, characterized in that, In step S2, the amount of the persulfate salt is 0.02-0.3 Kg / L.

10. The treatment process of p-nitrochlorobenzene production wastewater according to claim 1, characterized in that, In step S2, the wavelength of the ultraviolet light is 365 nm, and the irradiation time is 90-120 minutes.

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