Method for catalytic oxidation treatment of 1, 2-hexanediol production wastewater

Abstract

The invention belongs to the field of fine chemical wastewater treatment, and particularly relates to a method for treating 1, 2-hexanediol production wastewater through catalytic oxidation. The method comprises the following steps: adding a catalyst and hydrogen peroxide into wastewater to be treated to carry out oxidation reaction, and adding a calcium salt flocculant under an alkaline condition to carry out flocculent precipitation, thereby realizing removal of 1, 2-hexanediol and COD (Chemical Oxygen Demand). According to the method disclosed by the invention, the activated carbon loaded peroxyphosphotungstic acid quaternary ammonium salt catalyst has high oxidation catalytic activity, and the residual 1, 2-hexanediol in the 1, 2-hexanediol production wastewater can be effectively removed through further flocculation treatment of calcium hydroxide. The method not only solves the problem of activity inhibition of 1, 2-hexanediol on microorganisms, but also reduces the content of organic matters in the wastewater and improves the biodegradability of the wastewater. The method is simple to operate, low in cost and wide in commercial application prospect.

Description

Technical Field

[0001] The invention belongs to the field of fine chemical wastewater treatment, and specifically relates to a method for catalytic oxidation treatment of 1,2-hexanediol production wastewater. Background Art

[0002] 1,2-Hexanediol is a colorless and odorless liquid and is an important raw material for pesticides such as pyrethroids and cyclic musk. At the same time, due to its excellent moisturizing and antiseptic properties, it is also widely used in cosmetics.

[0003] Using 1-hexene as raw material and hydrogen peroxide as oxygen source, an epoxidation intermediate is generated in the presence of an inorganic solid acid catalyst, and then hydrolyzed under inorganic acid catalysis to obtain the product 1,2-hexanediol. In production, it must be refined by distillation. A large amount of wastewater will be generated in the distillation step. The COD concentration of the wastewater is about 1000 mg / L. The organic matter contained is mainly 1,2-hexanediol, which is highly toxic to microorganisms and can inhibit the activity of microorganisms. The biochemical treatment effect after dilution is also very poor, which does not meet the relevant environmental protection requirements. Due to the inhibitory effect of 1,2-hexanediol on microorganisms, the wastewater containing 1,2-hexanediol obtained by distillation is not suitable for direct biological treatment, and there is no report on the treatment method of wastewater containing 1,2-hexanediol. Summary of the invention

[0004] In order to overcome the above-mentioned shortcomings, the present invention provides a method for catalytic oxidation treatment of 1,2-hexanediol production wastewater. The present invention adopts activated carbon-loaded peroxyphosphotungstate quaternary ammonium salt catalyst, which can effectively treat 1,2-hexanediol in the wastewater, avoid the inhibition of 1,2-hexanediol in the wastewater on microorganisms in the biochemical treatment pool, and improve the biodegradability of the wastewater.

[0005] In order to achieve the above object, the technical solution adopted by the present invention is:

[0006] A method for treating 1,2-hexanediol production wastewater by catalytic oxidation, comprising adding a catalyst and hydrogen peroxide to the wastewater to be treated for oxidation reaction, adding a calcium salt flocculant under alkaline conditions for flocculation and precipitation, thereby achieving the removal of 1,2-hexanediol and COD.

[0007] Furthermore, a catalyst is added to the wastewater to be treated, and hydrogen peroxide is added dropwise at 60-70°C. After reacting for 2-3 hours, the catalyst is filtered out, the pH is adjusted to 12.0-13.0, a calcium salt flocculant is added, and the reaction is carried out at 80-90°C for 1-2 hours. After cooling to room temperature, the precipitate is filtered out, thereby achieving the removal of 1,2-hexanediol and COD.

[0008] Preferably, a catalyst is added to the wastewater to be treated, hydrogen peroxide is added dropwise at 65°C, the catalyst is filtered out after reacting for 2.5 hours, the pH is adjusted to 12.5, a calcium salt flocculant is added, the reaction is carried out at 85°C for 1.5 hours, the temperature is cooled to room temperature and the precipitate is filtered out, thereby achieving the removal of 1,2-hexanediol and COD.

[0009] The amount of the catalyst added is 0.05-0.15% of the mass of the wastewater to be treated; preferably, the amount of the catalyst added is 0.1% of the mass of the wastewater;

[0010] The amount of hydrogen peroxide added is 0.4-0.6% of the mass of the wastewater to be treated; preferably, the mass of hydrogen peroxide added is 0.5% of the mass of the wastewater;

[0011] The amount of calcium salt flocculant aqueous solution added is 0.8-1.2% of the mass of the wastewater to be treated.

[0012] The calcium salt flocculant is one or more of calcium acid, calcium chloride, calcium hydroxide and calcium oxide. The preferred calcium salt flocculant is calcium hydroxide.

[0013] The catalyst is an activated carbon-supported quaternary ammonium peroxyphosphotungstate catalyst;

[0014] The preparation method of the activated carbon-supported peroxyphosphotungstate quaternary ammonium salt catalyst comprises the following steps: dissolving phosphotungstic acid in distilled water, adding hydrogen peroxide to obtain a peroxyphosphotungstic acid solution; adding benzyltriethylammonium chloride to ethanol, and then adding activated carbon to obtain a benzyltriethylammonium chloride ethanol solution; adding the peroxyphosphotungstic acid solution to the benzyltriethylammonium chloride ethanol solution, stirring at a constant temperature, cooling and standing, filtering, and drying to obtain the activated carbon-supported peroxyphosphotungstate quaternary ammonium salt catalyst.

[0015] The amount of distilled water used is 8 to 12 times the mass of phosphotungstic acid, and the amount of hydrogen peroxide used is 1.3 to 1.7 times the mass of phosphotungstic acid;

[0016] The amount of benzyltriethylammonium chloride used is 1.2 to 1.4 times the mass of phosphotungstic acid, the amount of ethanol used is 8 to 12 times the mass of benzyltriethylammonium chloride, and the amount of activated carbon used is 3.5 to 4.5 times the mass of phosphotungstic acid.

[0017] The preferred conditions are: the amount of distilled water is 10 times the mass of phosphotungstic acid, the amount of hydrogen peroxide is 1.5 times the mass of phosphotungstic acid, the amount of benzyltriethylammonium chloride is 1.3 times the mass of phosphotungstic acid, the amount of ethanol is 10 times the mass of benzyltriethylammonium chloride, and the amount of activated carbon is 4.0 times the mass of phosphotungstic acid.

[0018] In the preparation method of the catalyst, the process conditions are: insulation temperature of 70-78°C, insulation stirring time of 4-8h, cooling to 15-25°C, standing for 12-24h, drying temperature of 220-230°C, and drying time of 4-5h. The preferred conditions are: insulation temperature of 78°C, insulation stirring time of 6h, cooling to 20°C, standing for 18h, drying temperature of 225°C, and drying time of 4.5h.

[0019] The principle of the present invention is that 1,2-hexanediol in wastewater undergoes degradation reaction under the action of catalyst and hydrogen peroxide, and is degraded into aldehyde compounds; the aldehyde degradation products undergo polymerization reaction under the catalysis of calcium hydroxide, and are filtered and removed after flocculation and precipitation, so that the content of organic matter such as 1,2-hexanediol in the wastewater is reduced, thereby achieving the purpose of reducing the COD of the wastewater, and at the same time, the inhibitory effect of 1,2-hexanediol in the wastewater on microorganisms is weakened, which is beneficial to the final biochemical treatment.

[0020] Compared with the prior art, the advantages of the present invention are:

[0021] The present invention adopts activated carbon-supported peroxyphosphotungstate quaternary ammonium salt catalyst, which has high oxidation catalytic activity, and further flocculation treatment with calcium hydroxide can effectively remove residual 1,2-hexanediol in 1,2-hexanediol production wastewater. At the same time, the COD removal rate of the method of the present invention reaches more than 70%, which not only solves the inhibition of 1,2-hexanediol on the activity of microorganisms, but also reduces the organic matter content of the wastewater and improves the biodegradability of the wastewater. The method of the present invention is simple to operate, low in cost, and has broad prospects for commercial application. DETAILED DESCRIPTION

[0022] The present invention will be further explained below through specific examples.

[0023] The main component of the wastewater to be treated is 1,2-hexanediol, the COD of the wastewater is about 1000 mg / kg, and the content of 1,2-hexanediol is 0.042%.

[0024] Example 1

[0025] Weigh 5.0g of phosphotungstic acid, place it in a beaker, add 50g of distilled water to dissolve, stir and add 7.5g of 30% w / w hydrogen peroxide, stir at room temperature for 30min to obtain peroxyphosphotungstic acid solution. Weigh 6.5g of benzyltriethylammonium chloride, place it in a three-necked flask, add 65g of ethanol, stir to dissolve, and then add 20.0g of activated carbon to obtain benzyltriethylammonium chloride ethanol solution. At room temperature, add the peroxyphosphotungstic acid solution dropwise to the benzyltriethylammonium chloride ethanol solution, heat to 78℃ and reflux slightly, stir for 6h, cool to 20℃, stand for 18h, filter, rinse the filter cake with water and ethanol respectively, and dry the filter cake at 225℃ for 4.5h to obtain activated carbon-supported peroxyphosphotungstic acid quaternary ammonium salt catalyst.

[0026] Example 2

[0027] Weigh 5.0g of phosphotungstic acid, place it in a beaker, add 40g of distilled water to dissolve, stir and add 6.5g of 30% w / w hydrogen peroxide, stir at room temperature for 30min to obtain peroxyphosphotungstic acid solution. Weigh 6.0g of benzyltriethylammonium chloride, place it in a three-necked flask, add 72g of ethanol, stir to dissolve, and then add 22.5g of activated carbon to obtain benzyltriethylammonium chloride ethanol solution. At room temperature, add the peroxyphosphotungstic acid solution dropwise to the benzyltriethylammonium chloride ethanol solution, heat to 75℃, stir for 8h, cool to 25℃, stand for 24h, filter, rinse the filter cake with water and ethanol respectively, and dry the filter cake at 230℃ for 4h to obtain activated carbon-supported peroxyphosphotungstic acid quaternary ammonium salt catalyst.

[0028] Example 3

[0029] Weigh 5.0g of phosphotungstic acid, place it in a beaker, add 60g of distilled water to dissolve, stir and add 8.5g of 30% w / w hydrogen peroxide, stir at room temperature for 30min to obtain peroxyphosphotungstic acid solution. Weigh 7.0g of benzyltriethylammonium chloride, place it in a three-necked flask, add 56g of ethanol, stir to dissolve, and then add 17.5g of activated carbon to obtain benzyltriethylammonium chloride ethanol solution. At room temperature, add the peroxyphosphotungstic acid solution dropwise to the benzyltriethylammonium chloride ethanol solution, heat to 76℃, stir for 4h, cool to 15℃, stand for 12h, filter, rinse the filter cake with water and ethanol respectively, and dry the filter cake at 220℃ for 5h to obtain the catalyst.

[0030] Example 4

[0031] 500 g of 1,2-hexanediol production wastewater was placed in a 1L three-necked flask, 0.5 g of the catalyst prepared in Example 1 was added, the mixture was stirred and heated to 65°C, 2.5 g of 30% hydrogen peroxide was added dropwise, the reaction was continued for 2.5 h, the temperature was lowered, and the catalyst was filtered out.

[0032] Add saturated sodium hydroxide aqueous solution to the filtrate to adjust the pH to 12.50, add 5.0 g of 10% calcium hydroxide aqueous solution, stir and heat to 85°C, keep the temperature for 1.5 hours, cool to room temperature, filter out the flocculated precipitate, and obtain the treated wastewater.

[0033] The treatment effect is: the COD removal rate of the wastewater is 82%, the content of 1,2-hexanediol in the treated wastewater is 0.007%, and the treated wastewater can be used for subsequent microbial treatment.

[0034] Example 5

[0035] 500 g of 1,2-hexanediol production wastewater was placed in a 1L three-necked flask, 0.25 g of the catalyst prepared in Example 2 was added, the temperature was raised to 70° C. with stirring, 3.0 g of 30% hydrogen peroxide was added dropwise, the reaction was continued for 3.0 h, the temperature was lowered, and the catalyst was filtered out.

[0036] Add saturated sodium hydroxide aqueous solution to the filtrate to adjust the pH to 12.00, add 6.0 g of 10% calcium hydroxide aqueous solution, stir and heat to 80°C, keep the temperature for 2.0 hours, cool to room temperature, filter out the flocculated precipitate, and obtain pretreated wastewater.

[0037] The treatment effect is: COD removal rate is 73%, the content of 1,2-hexanediol after pretreatment is 0.011%, and the treated wastewater can be used for subsequent microbial treatment.

[0038] Example 6

[0039] 500 g of 1,2-hexanediol production wastewater was placed in a 1L three-necked flask, 0.75 g of the catalyst prepared in Example 3 was added, the temperature was raised to 60° C. with stirring, 2.0 g of 30% hydrogen peroxide was added dropwise, the reaction was continued for 2.0 h, the temperature was lowered, and the catalyst was filtered out.

[0040] Add saturated sodium hydroxide aqueous solution to the filtrate to adjust the pH to 13.00, add 4.0 g of 10% calcium hydroxide aqueous solution, stir and heat to 90°C, keep the temperature for 1.0 h, cool to room temperature, filter out the flocculated precipitate, and obtain pretreated wastewater.

[0041] The treatment effect is: COD removal rate is 79%, the content of 1,2-hexanediol wastewater after pretreatment is 0.008%, and the treated wastewater can be used for subsequent microbial treatment.

[0042] Comparative Example 1

[0043] The difference from Example 4 is that the catalyst uses conventional catalyst phosphotungstic acid, and the other conditions are the same as those in Example 4, specifically:

[0044] Take 500g of 1,2-hexanediol production wastewater and place it in a 1L three-necked flask, add 0.5g of conventional catalyst phosphotungstic acid, stir and heat to 65°C, add 2.5g of 30% hydrogen peroxide dropwise, continue the reaction for 2.5h, cool down and filter out the catalyst.

[0045] Add saturated sodium hydroxide aqueous solution to the filtrate to adjust the pH to 12.50, add 5.0 g of 10% calcium hydroxide aqueous solution, stir and heat to 85°C, keep the temperature for 1.5 hours, cool to room temperature, filter and obtain treated wastewater.

[0046] The treatment effect is: the COD removal rate of the wastewater is 3%, the content of 1,2-hexanediol in the treated wastewater is 0.040%, and the treated wastewater has an inhibitory effect on microorganisms and cannot be used for subsequent microbial biochemical treatment.

[0047] Comparative Example 2

[0048] The difference from Example 4 is that the preparation method of the activated carbon-supported peroxyphosphomolybdic acid quaternary ammonium salt catalyst is different, and other conditions are the same as in Example 4, specifically:

[0049] Weigh 5.0g of phosphotungstic acid, place it in a beaker, add 50g of distilled water to dissolve, stir and add 7.5g of 30% w / w hydrogen peroxide, stir at room temperature for 30min to obtain peroxyphosphotungstic acid solution. Weigh 9.4g of hexadecyltrimethylammonium chloride, place it in a three-necked flask, add 65g of ethanol, stir to dissolve, and then add 20.0g of activated carbon to obtain hexadecyltrimethylammonium chloride ethanol solution. At room temperature, add the peroxyphosphotungstic acid solution dropwise to the hexadecyltrimethylammonium chloride ethanol solution, heat to 78℃ and reflux slightly, stir for 6h, cool to 20℃, stand for 18h, filter, rinse the filter cake with water and ethanol respectively, and dry the filter cake at 225℃ for 4.5h to obtain activated carbon-supported peroxyphosphotungstic acid quaternary ammonium salt catalyst.

[0050] Take 500 g of 1,2-hexanediol production wastewater and place it in a 1L three-necked flask, add 0.5 g of the catalyst prepared in the previous step, stir and heat to 65°C, add 2.5 g of 30% hydrogen peroxide solution dropwise, continue the reaction for 2.5 hours, cool down and filter out the catalyst.

[0051] Add saturated sodium hydroxide aqueous solution to the filtrate to adjust the pH to 12.50, add 5.0 g of 10% calcium hydroxide aqueous solution, stir and heat to 85°C, keep the temperature for 1.5 hours, cool to room temperature, filter out the flocculated precipitate, and obtain the treated wastewater.

[0052] The treatment effect is: the COD removal rate of the wastewater is 16%, the content of 1,2-hexanediol in the pretreated wastewater is 0.032%, and the treated wastewater inhibits the growth of microorganisms and cannot be used for subsequent biochemical treatment.

[0053] It can be seen from Comparative Examples 1 and 2 that when the catalyst of Comparative Example 1 uses conventional phosphotungstic acid, the treatment effect is not good, and the treated wastewater cannot be used for subsequent microbial biochemical treatment. When hexadecyltrimethylammonium chloride ethanol is used instead of benzyltriethylammonium chloride ethanol solution to prepare activated carbon-supported peroxyphosphomolybdic acid quaternary ammonium salt catalyst, the COD and 1,2-hexanediol treatment effect of the wastewater is not good, and the treated wastewater cannot be used for subsequent microbial biochemical treatment. The embodiment of the present invention uses activated carbon-supported peroxyphosphotungstic acid quaternary ammonium salt catalyst, which has high oxidation catalytic activity, and further flocculation treatment with calcium hydroxide can effectively remove residual 1,2-hexanediol in 1,2-hexanediol production wastewater.

Claims

1. A method for treating 1,2-hexanediol production wastewater by catalytic oxidation, characterized in that: A catalyst and hydrogen peroxide are added to the wastewater to be treated for oxidation reaction, and a calcium salt flocculant is added under alkaline conditions for flocculation and precipitation, thereby achieving the removal of 1,2-hexanediol and COD.

2. The method for treating 1,2-hexanediol production wastewater by catalytic oxidation according to claim 1, characterized in that: Add a catalyst to the wastewater to be treated, add hydrogen peroxide dropwise at 60-70°C, react for 2-3 hours, filter out the catalyst, adjust the pH to 12.0-13.0, add a calcium salt flocculant, react at 80-90°C for 1-2 hours, cool to room temperature, and filter out the precipitate, thereby achieving the removal of 1,2-hexanediol and COD.

3. The method for treating 1,2-hexanediol production wastewater by catalytic oxidation according to claim 2, characterized in that: Add a catalyst to the wastewater to be treated, add hydrogen peroxide dropwise at 65°C, react for 2.5 hours, filter out the catalyst, adjust the pH to 12.5, add a calcium salt flocculant, react at 85°C for 1.5 hours, cool to room temperature, and filter out the precipitate to achieve the removal of 1,2-hexanediol and COD.

4. The method for treating 1,2-hexanediol production wastewater by catalytic oxidation according to claim 1 or 2, characterized in that: The amount of the catalyst added is 0.05-0.15% of the mass of the wastewater to be treated; The amount of hydrogen peroxide added is 0.4-0.6% of the mass of the wastewater to be treated; The amount of calcium salt flocculant aqueous solution added is 0.8-1.2% of the mass of the wastewater to be treated.

5. The method for treating 1,2-hexanediol production wastewater by catalytic oxidation according to claim 4, characterized in that: The calcium salt flocculant is one or more of calcium acid, calcium chloride, calcium hydroxide and calcium oxide.

6. The method for treating 1,2-hexanediol production wastewater by catalytic oxidation according to claim 4, characterized in that: The catalyst is an activated carbon-supported peroxyphosphotungstate quaternary ammonium salt catalyst; the preparation method of the activated carbon-supported peroxyphosphotungstate quaternary ammonium salt catalyst is as follows: dissolving phosphotungstic acid in distilled water, adding hydrogen peroxide to obtain a peroxyphosphotungstic acid solution; simultaneously adding benzyltriethylammonium chloride to ethanol, and then adding activated carbon to obtain a benzyltriethylammonium chloride ethanol solution; adding the peroxyphosphotungstic acid solution to the benzyltriethylammonium chloride ethanol solution, keeping warm and stirring, cooling and standing, filtering, and drying to obtain the activated carbon-supported peroxyphosphotungstate quaternary ammonium salt catalyst.

7. The method for treating 1,2-hexanediol production wastewater by catalytic oxidation according to claim 6, characterized in that: The amount of distilled water used is 8 to 12 times the mass of phosphotungstic acid, and the amount of hydrogen peroxide used is 1.3 to 1.7 times the mass of phosphotungstic acid; The amount of benzyltriethylammonium chloride used is 1.2 to 1.4 times the mass of phosphotungstic acid, the amount of ethanol used is 8 to 12 times the mass of benzyltriethylammonium chloride, and the amount of activated carbon used is 3.5 to 4.5 times the mass of phosphotungstic acid.

8. The method for treating 1,2-hexanediol production wastewater by catalytic oxidation according to claim 6, characterized in that: The insulation temperature is 70-78°C, and the insulation time is 4-8h; cool down to 15-25°C, let stand for 12-24h, and the drying temperature is 220-230°C, and the drying time is 4-5h.

9. The method for treating 1,2-hexanediol production wastewater by catalytic oxidation according to claim 7, characterized in that: The amount of distilled water used is 10 times the mass of phosphotungstic acid, and the amount of hydrogen peroxide used is 1.5 times the mass of phosphotungstic acid; The amount of benzyltriethylammonium chloride used is 1.3 times the mass of phosphotungstic acid, the amount of ethanol used is 10 times the mass of benzyltriethylammonium chloride, and the amount of activated carbon used is 4.0 times the mass of phosphotungstic acid.

10. The method for treating 1,2-hexanediol production wastewater by catalytic oxidation according to claim 8, characterized in that: The insulation temperature is 78℃, and the insulation time is 6h; cool down to 20℃, let stand for 18h, and the drying temperature is 225℃, and the drying time is 4.5h.