阅读说明：本技术 一种处理苯酚废水的光催化剂及其制备方法和处理方法 (Photocatalyst for treating phenol wastewater and preparation method and treatment method thereof ) 是由 谢绵锐 于 2019-12-13 设计创作，主要内容包括：本发明属于废水处理领域,具体涉及一种处理苯酚废水的光催化剂及其制备方法和处理苯酚废水的方法。能够提高纳米TiO2/ZSM-5复合光催化剂的稳定性,使其重复用于污水处理。本发明采用改进纳米TiO2/ZSM-5复合光催化剂的制备工艺,采用合理的温度和二次骤冷处理,提高了复合催化剂的稳定性和处理效率,能够处理高苯酚浓度废水,也能处理苯酚浓度小于50mg/L的废水,处理苯酚废水时的处理效率高,能够利用太阳光,无需密闭环境,节约能耗,减少投资。能够多次重复使用,效果衰减小。(The invention belongs to the field of wastewater treatment, and particularly relates to a photocatalyst for treating phenol wastewater, a preparation method of the photocatalyst and a method for treating the phenol wastewater. The stability of the nano TiO2/ZSM-5 composite photocatalyst can be improved, so that the nano TiO2/ZSM-5 composite photocatalyst can be repeatedly used for sewage treatment. The preparation method adopts the preparation process of the improved nano TiO2/ZSM-5 composite photocatalyst, adopts reasonable temperature and secondary quenching treatment, improves the stability and treatment efficiency of the composite photocatalyst, can treat wastewater with high phenol concentration and wastewater with the phenol concentration less than 50mg/L, has high treatment efficiency when treating the phenol wastewater, can utilize sunlight, does not need a closed environment, saves energy consumption and reduces investment. Can be repeatedly used for many times, and the effect attenuation is reduced.)

1. A preparation method of a photocatalyst for treating phenol wastewater is characterized by comprising the following steps:

step a, preparing modified ZSM-5 zeolite;

1) placing ZSM-5 zeolite into a NaOH solution according to a liquid-solid ratio of 10-130 mL/g, wherein the concentration of NaOH is 0.5-5 mol/L, stirring for 20-90min at room temperature, heating for 1-10h at 40-200 ℃ in a closed reaction kettle, filtering and washing;

2) mixing the base-treated ZSM-5 zeolite obtained in the step 1) with a sulfuric acid solution, wherein the concentration of the sulfuric acid solution is 0.2-3 mol/L; the liquid-solid ratio of the acid solution to the ZSM-5 zeolite is 20-120 mL/g, then stirring and processing are carried out for 0.5-8 h at 50-170 ℃, drying is carried out for 3-6h in a drying oven at 650 ℃ with 400-170 ℃ after filtering and washing, then quenching is carried out, and the temperature is reduced to below 10 ℃, so that the obtained solid is the modified zeolite ZSM-5;

step b, preparing a nano TiO2/ZSM-5 composite photocatalyst;

the method comprises the following steps: dropwise adding tetrabutyl titanate into absolute ethyl alcohol under the stirring condition, and uniformly stirring to obtain a component A; stirring and uniformly mixing absolute ethyl alcohol, distilled water and concentrated nitric acid to obtain a component B; dropwise adding the component B into the component A under the stirring condition to obtain light yellow transparent sol; adding the ZSM-5 prepared in the step a, uniformly stirring, forming gel in a constant-temperature water bath kettle at 35-65 ℃, heating and drying in a constant-temperature water bath kettle at 70-90 ℃, washing the obtained powder with deionized water, adding the powder into a muffle furnace preheated to 280-500 ℃, roasting for 2-4h, cooling to 180-250 ℃ at the speed of cooling to 0.5 ℃ per minute, quenching to room temperature, and grinding into powder to obtain the nano TiO2/ZSM-5 composite photocatalyst.

2. The method of claim 1, wherein the process temperature before the second quenching is lower than the temperature before the first quenching.

3. The method for preparing a photocatalyst for treating phenolic wastewater according to any one of claims 1 and 2, characterized in that: in the step B, the volume ratio of tetrabutyl titanate to absolute ethyl alcohol in the component A is 1:2-4, the volume ratio of absolute ethyl alcohol, distilled water and concentrated nitric acid in the component B is 30:3:2, the mass concentration of the concentrated nitric acid is 65%, and the volume ratio of the component A, B is 3:2, adding the modified ZSM-5 zeolite according to the liquid-solid ratio of 30 mL/g.

4. A method for treating phenol wastewater is characterized by comprising the following steps:

putting the TiO2/ZSM-5 composite photocatalyst into phenol wastewater, adding ferrous sulfate and sodium persulfate, stirring and mixing, and then carrying out photocatalytic degradation by taking sunlight and an ultraviolet high-pressure mercury lamp as light sources;

3-7 parts of TiO2/ZSM-5 composite photocatalyst, 2-5 parts of ferrous sulfate and 1-3 parts of sodium persulfate according to the mass ratio;

the photocatalytic degradation condition is that sunlight and a 150-250W ultraviolet high-pressure mercury lamp are irradiated for 30-90 min;

the TiO2/ZSM-5 composite photocatalyst is filtered and recovered and then repeatedly used for wastewater treatment, and is heated at 400 ℃ by a muffle furnace after being repeatedly used for many times.

5. The method for treating phenol wastewater according to claim 4, characterized in that: the concentration of phenol in the wastewater is within 250 mg/L.

6. The method for preparing a photocatalyst for treating phenolic wastewater according to any one of claims 1 to 3, characterized by comprising the steps of:

step a, preparing modified ZSM-5 zeolite;

1) placing ZSM-5 zeolite into NaOH solution according to a liquid-solid ratio of 20mL/g, wherein the concentration of NaOH is 4mol/L, stirring for 22min at room temperature, heating for 1.5h at 50 ℃ in a closed reaction kettle, filtering and washing;

2) mixing the ZSM-5 zeolite obtained in the step 1) after the alkali treatment with a sulfuric acid solution, wherein the concentration of the sulfuric acid solution is 2.5 mol/L; the liquid-solid ratio of the acid solution to the ZSM-5 zeolite is 30mL/g, then stirring the mixture for 1h at 65 ℃, filtering and washing the mixture, drying the mixture for 4h in a 480 ℃ oven, then quenching the mixture, and cooling the cooled mixture to 3 ℃, wherein the obtained solid is the modified zeolite ZSM-5.

Step b, preparing a nano TiO2/ZSM-5 composite photocatalyst;

the method comprises the following steps: dropwise adding tetrabutyl titanate into absolute ethyl alcohol under the stirring condition, and uniformly stirring to obtain a component A; stirring and uniformly mixing absolute ethyl alcohol, distilled water and concentrated nitric acid to obtain a component B; dropwise adding the component B into the component A under the stirring condition to obtain light yellow transparent sol; and (b) adding the ZSM-5 prepared in the step (a), uniformly stirring, forming gel in a constant-temperature water bath kettle at 60 ℃, heating and drying in the constant-temperature water bath kettle at 90 ℃, washing the obtained powder with deionized water, adding the powder into a muffle furnace preheated to 450 ℃, roasting for 2.5h, cooling to 220 ℃ at a speed of 0.5 ℃ per minute, quenching to room temperature, and grinding into powder to obtain the nano TiO2/ZSM-5 composite photocatalyst.

In the step B, the volume ratio of tetrabutyl titanate to absolute ethyl alcohol in the component A is 1:2.2, the volume ratio of absolute ethyl alcohol, distilled water and concentrated nitric acid in the component B is 30:3:2, the mass concentration of the concentrated nitric acid is 65%, and the volume ratio of the component A, B is 3:2, adding the modified ZSM-5 zeolite according to the liquid-solid ratio of 30 mL/g.

7. The method for preparing a photocatalyst for treating phenolic wastewater according to any one of claims 1 to 3, characterized by comprising the steps of:

step a, preparing modified ZSM-5 zeolite;

1) placing ZSM-5 zeolite into NaOH solution according to a liquid-solid ratio of 120mL/g, wherein the concentration of NaOH is 0.8mol/L, stirring for 80min at room temperature, heating for 9h at 190 ℃ in a closed reaction kettle, filtering and washing;

2) mixing the ZSM-5 zeolite obtained in the step 1) after the alkali treatment with a sulfuric acid solution, wherein the concentration of the sulfuric acid solution is 0.4 mol/L; the liquid-solid ratio of the acid solution to the ZSM-5 zeolite is 110mL/g, then the mixture is stirred at 150 ℃ for 7 hours, after filtration and washing, the mixture is dried in a 600 ℃ oven for 5 hours, then the mixture is quenched and cooled to 10 ℃, and the obtained solid is the modified zeolite ZSM-5.

Step b, preparing a nano TiO2/ZSM-5 composite photocatalyst;

the method comprises the following steps: dropwise adding tetrabutyl titanate into absolute ethyl alcohol under the stirring condition, and uniformly stirring to obtain a component A; stirring and uniformly mixing absolute ethyl alcohol, distilled water and concentrated nitric acid to obtain a component B; dropwise adding the component B into the component A under the stirring condition to obtain light yellow transparent sol; and (b) adding the ZSM-5 prepared in the step (a), uniformly stirring, forming gel in a constant-temperature water bath kettle at 40 ℃, heating and drying in a constant-temperature water bath kettle at 80 ℃, washing the obtained powder with deionized water, adding the powder into a muffle furnace preheated to 300 ℃, roasting for 3.5h, cooling to 190 ℃ at a speed of 0.5 ℃ per minute, quenching to room temperature, and grinding into powder to obtain the nano TiO2/ZSM-5 composite photocatalyst.

In the step B, the volume ratio of tetrabutyl titanate to absolute ethyl alcohol in the component A is 1:3.2, the volume ratio of absolute ethyl alcohol, distilled water and concentrated nitric acid in the component B is 30:3:2, the mass concentration of the concentrated nitric acid is 65%, and the volume ratio of the component A, B is 3:2, adding the modified ZSM-5 zeolite according to the liquid-solid ratio of 30 mL/g.

8. The method for preparing a photocatalyst for treating phenolic wastewater according to any one of claims 1 to 3, characterized by comprising the steps of:

step a, preparing modified ZSM-5 zeolite;

1) placing ZSM-5 zeolite into NaOH solution according to a liquid-solid ratio of 70mL/g, wherein the concentration of NaOH is 3mol/L, stirring for 60min at room temperature, heating for 5.5h at 120 ℃ in a closed reaction kettle, filtering and washing;

2) mixing the ZSM-5 zeolite obtained in the step 1) after the alkali treatment with a sulfuric acid solution, wherein the concentration of the sulfuric acid solution is 1.6 mol/L; the liquid-solid ratio of the acid solution to the ZSM-5 zeolite is 80mL/g, then stirring and processing are carried out for 4h at the temperature of 110 ℃, after filtration and washing, drying is carried out for 4h in a 520 ℃ oven, then quenching is carried out, the temperature is reduced to below 8 ℃, and the obtained solid is the modified zeolite ZSM-5.

Step b, preparing a nano TiO2/ZSM-5 composite photocatalyst;

the method comprises the following steps: dropwise adding tetrabutyl titanate into absolute ethyl alcohol under the stirring condition, and uniformly stirring to obtain a component A; stirring and uniformly mixing absolute ethyl alcohol, distilled water and concentrated nitric acid to obtain a component B; dropwise adding the component B into the component A under the stirring condition to obtain light yellow transparent sol; and (b) adding the ZSM-5 prepared in the step (a), uniformly stirring, forming gel in a constant-temperature water bath kettle at 50 ℃, heating and drying in a constant-temperature water bath kettle at 80 ℃, washing the obtained powder with deionized water, adding the powder into a muffle furnace preheated to 390 ℃, roasting for 3h, cooling to 240 ℃ at the speed of cooling to 0.5 ℃ per minute, quenching to room temperature, and grinding into powder to obtain the nano TiO2/ZSM-5 composite photocatalyst.

In the step B, the volume ratio of tetrabutyl titanate to absolute ethyl alcohol in the component A is 1:3, the volume ratio of absolute ethyl alcohol, distilled water and concentrated nitric acid in the component B is 30:3:2, the mass concentration of the concentrated nitric acid is 65%, and the volume ratio of the component A, B is 3:2, adding the modified ZSM-5 zeolite according to the liquid-solid ratio of 30 mL/g.

Technical Field

The invention belongs to the field of wastewater treatment, and particularly relates to a photocatalyst for treating phenol wastewater, a preparation method of the photocatalyst and a method for treating the phenol wastewater.

Background

A lot of researches on how to eliminate phenol in wastewater are carried out at home and abroad, and the researches are mainly embodied in that the phenol is subjected to photocatalytic degradation by using a photocatalyst. The prior art has good effect but has a plurality of defects by using the nano TiO2/ZSM-5 composite photocatalyst to treat phenol sewage. For example, the nano TiO2/ZSM-5 composite photocatalyst has too fast attenuation of treatment effect when being reused. The applicant has discovered the cause of the attenuation and solved the problem. Secondly, the nano TiO2/ZSM-5 composite catalyst obtained by the prior art has low quantity of nano TiO2 in ZSM-5, low activity and low sewage treatment efficiency. Is not suitable for treating the wastewater with high phenol concentration, and is also not suitable for treating the wastewater with the phenol concentration less than 50mg/L in the wastewater.

Disclosure of Invention

In order to solve the defects, the invention provides a photocatalyst for treating phenol wastewater and a preparation method thereof.

The invention also provides a method for treating the phenol wastewater, which is a method for treating the phenol wastewater by combining the nano TiO2/ZSM-5 composite photocatalyst with strong oxidizing sulfate radicals.

In order to realize the purpose of the invention, the invention adopts the following technical scheme:

a preparation method of a photocatalyst for treating phenol wastewater comprises the following steps:

step a, preparing modified ZSM-5 zeolite;

1) placing ZSM-5 zeolite into a NaOH solution according to a liquid-solid ratio of 10-130 mL/g, wherein the concentration of NaOH is 0.5-5 mol/L, stirring for 20-90min at room temperature, heating for 1-10h at 40-200 ℃ in a closed reaction kettle, filtering and washing;

2) mixing the base-treated ZSM-5 zeolite obtained in the step 1) with a sulfuric acid solution, wherein the concentration of the sulfuric acid solution is 0.2-3 mol/L; the liquid-solid ratio of the acid solution to the ZSM-5 zeolite is 20-120 mL/g, then stirring and processing are carried out for 0.5-8 h at 50-170 ℃, drying is carried out for 3-6h in a drying oven at 650 ℃ with 400-170 ℃ after filtering and washing, then quenching is carried out, and the temperature is reduced to below 10 ℃, so that the obtained solid is the modified zeolite ZSM-5.

The silicon-aluminum ratio (SiO2/Al2O3) of the ZSM-5 zeolite used in the step 1) is 18-30; relative crystallinity: na type > 85%; pore diameter: 5A degree);

step b, preparing a nano TiO2/ZSM-5 composite photocatalyst;

the method comprises the following steps: dropwise adding tetrabutyl titanate into absolute ethyl alcohol under the stirring condition, and uniformly stirring to obtain a component A; stirring and uniformly mixing absolute ethyl alcohol, distilled water and concentrated nitric acid to obtain a component B; dropwise adding the component B into the component A under the stirring condition to obtain light yellow transparent sol; adding the ZSM-5 prepared in the step a, uniformly stirring, forming gel in a constant-temperature water bath kettle at 35-65 ℃, heating and drying in a constant-temperature water bath kettle at 70-90 ℃, washing the obtained powder with deionized water, adding the powder into a muffle furnace preheated to 280-500 ℃, roasting for 2-4h, cooling to 180-250 ℃ at the speed of cooling to 0.5 ℃ per minute, quenching to room temperature, and grinding into powder to obtain the nano TiO2/ZSM-5 composite photocatalyst.

In the step B, the volume ratio of tetrabutyl titanate to absolute ethyl alcohol in the component A is 1:2-4, the volume ratio of absolute ethyl alcohol, distilled water and concentrated nitric acid in the component B is 30:3:2, the mass concentration of the concentrated nitric acid is 65%, and the volume ratio of the component A, B is 3:2, adding the modified ZSM-5 zeolite according to the liquid-solid ratio of 30 mL/g.

Quenching to room temperature allows the hot composite catalyst to pass directly through a cold gas or cooler, or to be added to cold water and filtered again for drying, all in the prior art.

The process temperature before the second quenching is lower than the temperature before the first quenching.

A method for treating phenol wastewater comprises the following steps:

putting the TiO2/ZSM-5 composite photocatalyst into phenol wastewater, adding ferrous sulfate and sodium persulfate, stirring and mixing, and then carrying out photocatalytic degradation by using sunlight and an ultraviolet high-pressure mercury lamp as light sources.

3-7 parts of TiO2/ZSM-5 composite photocatalyst, 2-5 parts of ferrous sulfate and 1-3 parts of sodium persulfate according to the mass ratio.

The concentration of phenol in the wastewater is within 250mg/L,

the photocatalytic degradation condition is that the sunlight and a 150-250W ultraviolet high-pressure mercury lamp are irradiated for 30-90 min.

The TiO2/ZSM-5 composite photocatalyst is filtered and recovered and then repeatedly used for wastewater treatment, and is heated at 400 ℃ by a muffle furnace after being repeatedly used for many times.

The molecular formula of the ferrous sulfate is FeSO4 & 7H 2O.

The applicant finds that after the nano TiO2/ZSM-5 composite photocatalyst is repeatedly used for treating phenol sewage for 5-6 times, the treatment effect of the photocatalyst is attenuated quickly, and specific analysis shows that in the production process, the ZSM-5 is treated by acid and alkali to generate a certain mesoporous structure, the void volume is increased, the diffusion resistance of substances is reduced, but partial structure of the ZSM-5 is collapsed, the consistency of the pore diameter is reduced, and the structure is fragile, although the nano TiO2 photocatalyst is stable in property, the nano TiO2/ZSM-5 composite photocatalyst is fragile in structure, the composite structure is easy to damage when the photocatalyst is repeatedly used, and the effect is quickly weakened. In addition, the collapse of the nano TiO2/ZSM-5 structure is aggravated, the structural strength is reduced, and even the nano TiO2/ZSM-5 structure is loose due to multiple times of heating, high-temperature roasting and persulfate oxidation in the process, when the nano TiO2/ZSM-5 structure is repeatedly used for treating wastewater, the composite structure is cracked and collapsed, the performance is aggravated and attenuated, and the reuse is not facilitated.

The small-grain molecular sieve structure is obtained by first quenching, so that the weak structure of the ZSM-5 part is pre-collapsed, the integral strength is enhanced, the aperture is increased, the consistency is good, and the prepared composite photocatalyst is prevented from being fragile, easy to collapse and ineffective; the slow temperature reduction before the second quenching is to ensure that a large amount of nano TiO2 is uniformly, stably and firmly embedded into the ZSM-5, so that the nano TiO2 is prevented from being separated from the ZSM-5 and the structure is prevented from collapsing in subsequent processing and use. The secondary quenching makes the composite catalyst form a small crystal grain structure, shortens the diffusion path of reactants, improves the efficiency of the composite catalyst, ensures that the ZSM-5 more stably fixes the nano TiO2, weakens the side effects caused by heating and oxidation, has high structural strength and can be repeatedly used for many times.

The process temperature before the second quenching is lower than that before the first quenching, so that small grains and the pore diameter generated in the first quenching are prevented from being damaged, and the grains after compounding are reformed, and the pore diameter consistency is better.

Has the advantages that: the invention improves the quantity and stability of the nano TiO2 in the ZSM-5, can treat wastewater with high phenol concentration and wastewater with the phenol concentration less than 50mg/L, has high treatment efficiency when treating the phenol wastewater, can utilize sunlight, does not need a closed environment, saves energy consumption and reduces investment. Can be repeatedly used for many times, and the effect attenuation is reduced.

Detailed Description

The technical solution of the present invention is further described below with reference to specific examples, but the present invention is not limited to the following examples. Unless otherwise indicated, the various components used in the present invention are all materials known in the art, and are either commercially available or prepared by known methods.