A method for resource treatment of epichlorohydrin wastewater using ultraviolet light

Abstract

The present invention provides a method for resource treatment of epichlorohydrin wastewater using ultraviolet light. Under the irradiation of a nano-bismuth trioxide catalyst supported on ZSM-5 molecular sieve and ultraviolet light, glycerol monomethyl ether and glycerol dimethyl ether in the epichlorohydrin wastewater are decomposed into glycerol and methanol. Methanol generated is removed by negative pressure, and then glycerol in the wastewater is adsorbed by XDA macroporous adsorption resin. After desorption, crude glycerol is obtained, and organic substances in the wastewater are recovered. The adsorbed effluent can be directly subjected to biochemical treatment. Moreover, the technical solution of the present invention has good connectivity with the previous steps. The source of the wastewater is the bottom of a methanol distillation column, and the hot feed can be directly pumped into a fixed-bed reactor. The outlet temperature of the fixed-bed reactor just meets the temperature requirement for negative-pressure removal of methanol. The temperature of the wastewater after methanol removal is further reduced, which can also meet the requirements of resin adsorption. The entire technical solution is coherent and ingeniously designed, enabling continuous production with simple operation.

Description

Technical Field

[0001] The present invention relates to the field of chemical wastewater treatment, and particularly to a method for resource treatment of epichlorohydrin wastewater using ultraviolet light. Background Art

[0002] Epichlorohydrin (ECH) is an important basic chemical raw material, mainly used in the production of various products such as epoxy resin, chlorohydrin rubber, and glycerol. At present, there are mainly two industrial production methods of epichlorohydrin: the chlorohydrin method and the glycerol method. The process of synthesizing epichlorohydrin using titanium silicalite molecular sieve as a catalyst and hydrogen peroxide as an oxygen source has become a research hotspot due to its high selectivity and less ineffective decomposition of hydrogen peroxide.

[0003] This process needs to use methanol as a solvent. After the reaction, the oil and water are separated. After the methanol in the water layer is recovered, the remaining wastewater has a low organic matter content. Generally, the organic matter in the wastewater is treated by oxidation and biochemical treatment. The organic matter in the wastewater is not recycled during this treatment process, resulting in waste of resources. Summary of the Invention

[0004] To solve the problems in the background art, the present invention provides the following technical solutions:

[0005] A method for resource treatment of epichlorohydrin wastewater using ultraviolet light, comprising the following steps:

[0006] S1: Fill a catalyst in a fixed-bed reactor, and under the irradiation of an ultraviolet lamp, introduce epichlorohydrin wastewater into the fixed-bed reactor for photocatalytic reaction;

[0007] S2: Remove methanol from the wastewater treated by the fixed-bed reactor under negative pressure;

[0008] S3: Introduce the wastewater from which methanol has been removed into a resin adsorption column. After the resin is saturated with adsorption, desorption and regeneration are carried out to obtain crude glycerol;

[0009] The source of the epichlorohydrin wastewater is the wastewater after methanol removal from the water layer in the hydrogen peroxide method epichlorohydrin process. The epichlorohydrin wastewater contains 0.05 - 0.07% of glycerol monomethyl ether, 0.15 - 0.23% of glycerol dimethyl ether, and the TOC is 4000 - 7000 mg / L;

[0010] The catalyst is a nano-bismuth trioxide catalyst supported on ZSM-5 molecular sieve, and the resin is XDA macroporous adsorption resin.

[0011] Further, the nano-bismuth trioxide catalyst supported on ZSM-5 molecular sieve is prepared by the following method: spherical ZSM-5 molecular sieve with a particle size of 2-5 mm is impregnated in a dilute nitric acid solution, Bi(NO3)3·5H2O is added, stirred and mixed, and ultrasonically dispersed for 24 h. After drying, it is calcined at 550 °C for 3 h to obtain the nano-bismuth trioxide catalyst supported on ZSM-5 molecular sieve.

[0012] Further, in the nano-bismuth trioxide catalyst supported on ZSM-5 molecular sieve, the loading amount of nano-bismuth trioxide is 0.1% - 1%.

[0013] Further, in S1, the ultraviolet light source is a mercury lamp, and its power is set at 2000 - 20000 W per cubic meter of fixed bed.

[0014] Further, in S1, the fixed bed reactor is made of a light-transmitting material, and the ultraviolet light source is arranged outside the fixed bed reactor; or, in S1, the fixed bed reactor is made of an opaque material, and the ultraviolet light source is arranged inside the fixed bed reactor.

[0015] Further, in S1, the temperature of the photocatalytic reaction is 60 - 80 °C.

[0016] Further, in S2, the conditions for negative pressure removal of methanol are 50 - 55 °C and the pressure is -0.085 MPa to -0.090 MPa.

[0017] Further, in S3, the filling rate of the resin in the resin adsorption column is 90%, the XDA macroporous adsorption resin is saturated after adsorbing 30 BV, and the saturated XDA macroporous adsorption resin is desorbed and regenerated with steam at 105 - 110 °C to obtain crude glycerol.

[0018] The beneficial effects of the present invention are:

[0019] The present invention provides a method for resource treatment of epichlorohydrin wastewater using ultraviolet light. Under the irradiation of a catalyst of nano-bismuth trioxide supported on ZSM-5 molecular sieve and ultraviolet light, glycerol monomethyl ether and glycerol dimethyl ether in the epichlorohydrin wastewater are decomposed into glycerol and methanol. Methanol generated is removed by negative pressure, and then glycerol in the wastewater is adsorbed by XDA macroporous adsorption resin. After desorption, crude glycerol is obtained, and organic substances in the wastewater are recovered, reducing the pressure of subsequent wastewater treatment. It can be directly treated by biochemical method. Moreover, the technical solution of the present invention has good connectivity with the previous steps. The source of the wastewater is the bottom of a methanol rectification column, and hot material can be directly pumped into a fixed bed reactor without the need for a heat source. The outlet temperature of the fixed bed reactor just meets the temperature requirement for removing methanol by negative pressure. The temperature of the wastewater after methanol removal is further reduced, which can also meet the requirements of resin adsorption and will not lead to poor adsorption effect due to too high temperature. The whole technical solution is coherent and ingeniously designed, and can be continuously produced with simple operation;

[0020] In addition, both the ZSM-5 molecular sieve and XDA macroporous adsorption resin used in the technical solution of the present invention are commercial products and can be directly purchased. The ZSM-5 molecular sieve with a particle size of 2 - 5 mm is selected as a spherical molecular sieve for the preparation of the catalyst. On the one hand, it meets the filling requirements of the fixed bed reactor, and on the other hand, the high heat resistance performance of the ZSM-5 molecular sieve can ensure that the catalyst does not cause the collapse of the framework during the calcination process. Specific Embodiments

[0021] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0022] Example 1

[0023] Preparation of nano-bismuth trioxide supported on ZSM-5 molecular sieve catalyst

[0024] 1000 g of spherical ZSM-5 molecular sieve with a particle size of 2 mm was impregnated in 2000 g of 2% dilute nitric acid solution, and 23.2 g of Bi(NO3)3·5H2O was added in batches. Stir and mix at room temperature and disperse ultrasonically for 24 h. After vacuum drying, it was calcined at 550 °C for 3 h to obtain a nano-bismuth trioxide supported on ZSM-5 molecular sieve catalyst with a Bi2O3 loading of about 1%.

[0025] Example 2

[0026] A method for resource treatment of epichlorohydrin wastewater using ultraviolet light, comprising the following steps:

[0027] S1: Fill 900 g of the ZSM-5 molecular sieve supported nano-bismuth trioxide catalyst prepared in Example 1 into a 2 L quartz tube fixed-bed reactor. Attach a 40 W ultraviolet lamp to the outside of the quartz tube fixed-bed reactor. Under ultraviolet light irradiation, feed the epichlorohydrin wastewater into the fixed-bed reactor at a flow rate of 10 L / h at room temperature for photocatalytic reaction;

[0028] S2: Heat the wastewater treated by the fixed-bed reactor to 50 °C and remove methanol under a negative pressure of -0.09 MPa;

[0029] S3: Feed the methanol-removed wastewater into a 2 L resin adsorption column at a flow rate of 10 L / h. The filling rate of XDA macroporous adsorption resin is 90%. After 6 h, the XDA macroporous adsorption resin is saturated with adsorption, and it is desorbed and regenerated with steam at 105 °C to obtain crude glycerol;

[0030] The source of the epichlorohydrin wastewater is the wastewater after methanol removal from the water layer in the hydrogen peroxide method epichlorohydrin process. The epichlorohydrin wastewater contains 0.06% glycerol monomethyl ether, 0.20% glycerol dimethyl ether, and the TOC is 5200 mg / L;

[0031] After being treated by the technical solution of the present invention, in the wastewater after resin adsorption, the content of glycerol monomethyl ether is less than 0.01%, the content of glycerol dimethyl ether is less than 0.01%, and the TOC is 320 mg / L;

[0032] Per ton of wastewater, 1.16 kg of methanol is recovered, 1.9 kg of glycerol is recovered, the oxidation step of wastewater treatment is reduced, and the treated wastewater can be directly used for biochemical treatment and reuse.

[0033] Example 3

[0034] Preparation of ZSM-5 molecular sieve supported nano-bismuth trioxide catalyst

[0035] Immerse 100 Kg of spherical ZSM-5 molecular sieve with a particle size of 5 mm in 200 Kg of 2% dilute nitric acid solution. Add 232 g of Bi(NO3)3·5H2O in batches, stir and mix at room temperature and disperse ultrasonically for 24 h. After vacuum drying, calcine at 550 °C for 3 h to obtain a ZSM-5 molecular sieve supported nano-bismuth trioxide catalyst with a Bi2O3 loading of about 0.1%.

[0036] Example 4

[0037] A method for resource treatment of epichlorohydrin wastewater using ultraviolet light, comprising the following steps:

[0038] S1: Fill 90 Kg of the ZSM-5 zeolite-supported nano-bismuth trioxide catalyst prepared in Example 3 into a 200 L fixed-bed reactor. The fixed-bed reactor is made of stainless steel, and a 400 W ultraviolet lamp is installed inside the fixed-bed reactor. Under ultraviolet light irradiation, epichlorohydrin wastewater at 80 °C is introduced into the fixed-bed reactor at a flow rate of 2000 L / h at room temperature for photocatalytic reaction;

[0039] S2: The temperature of the wastewater treated by the fixed-bed reactor is slightly cooled to 55 °C, and methanol is removed under a negative pressure of -0.085 MPa;

[0040] S3: Cool the wastewater from which methanol has been removed to 40 °C slightly, and introduce it into a 200 L resin adsorption column at a flow rate of 2000 L / h. The filling rate of XDA macroporous adsorption resin is 90%. After 3 h, the XDA macroporous adsorption resin is saturated with adsorption. Switch to the standby resin adsorption column, and the saturated XDA macroporous adsorption resin is desorbed and regenerated with 110 °C steam for 1 h to obtain crude glycerol;

[0041] The source of the epichlorohydrin wastewater is the wastewater after methanol removal from the water layer in the hydrogen peroxide method epichlorohydrin process. The epichlorohydrin wastewater contains 0.05% glycerol monomethyl ether, 0.15% glycerol dimethyl ether, and the TOC is 4000 mg / L;

[0042] After treatment by the technical solution of the present invention, in the wastewater after resin adsorption, the content of glycerol monomethyl ether is less than 0.01%, the content of glycerol dimethyl ether is less than 0.01%, and the TOC is 260 mg / L;

[0043] It is equivalent to recovering 0.86 kg of methanol and 1.41 kg of glycerol per ton of wastewater, reducing the oxidation step of wastewater treatment, and the treated wastewater can be directly used for biochemical treatment and reuse.

[0044] Example 5

[0045] Preparation of ZSM-5 zeolite-supported nano-bismuth trioxide catalyst

[0046] Immerse 100 Kg of spherical ZSM-5 zeolite with a particle size of 5 mm in 200 Kg of 2% dilute nitric acid solution, add 696 g of Bi(NO3)3·5H2O in batches, stir and mix at room temperature and disperse ultrasonically for 24 h. After vacuum drying, calcine at 550 °C for 3 h to obtain a ZSM-5 zeolite-supported nano-bismuth trioxide catalyst with a Bi2O3 loading of about 0.3%.

[0047] Example 6

[0048] A method for resource treatment of epichlorohydrin wastewater using ultraviolet light, comprising the following steps:

[0049] S1: Fill 90 Kg of the ZSM-5 zeolite-supported nano-bismuth trioxide catalyst prepared in Example 5 into a 200 L fixed-bed reactor. The fixed-bed reactor is made of stainless steel, and 4 * 400 W ultraviolet lamps are evenly arranged inside the fixed-bed reactor. Under ultraviolet light irradiation, epichlorohydrin wastewater at 60 °C is introduced into the fixed-bed reactor at a flow rate of 2000 L / h at room temperature for photocatalytic reaction;

[0050] S2: The temperature of the wastewater treated by the fixed-bed reactor is slightly cooled to 50 °C, and methanol is removed under a negative pressure of -0.090 MPa;

[0051] S3: Cool the wastewater from which methanol has been removed to 40 °C slightly, and introduce it into a 200 L resin adsorption column at a flow rate of 2000 L / h. The filling rate of XDA macroporous adsorption resin is 90%. After 3 h, the XDA macroporous adsorption resin is saturated with adsorption. Switch to the standby resin adsorption column, and the saturated XDA macroporous adsorption resin is desorbed and regenerated with 110 °C steam for 1 h to obtain crude glycerol;

[0052] The source of the epichlorohydrin wastewater is the wastewater after methanol removal from the water layer in the hydrogen peroxide method epichlorohydrin process. The epichlorohydrin wastewater contains 0.07% glycerol monomethyl ether, 0.23% glycerol dimethyl ether, and the TOC is 7000 mg / L;

[0053] After treatment by the technical solution of the present invention, in the wastewater after resin adsorption, the content of glycerol monomethyl ether is less than 0.01%, the content of glycerol dimethyl ether is less than 0.01%, and the TOC is 180 mg / L;

[0054] It is equivalent to recovering 1.35 Kg of methanol and 2.00 Kg of glycerol per ton of wastewater, reducing the oxidation step of wastewater treatment, and the treated wastewater can be directly used for biochemical treatment and reuse.

[0055] Finally, it should be noted that the above content is only used to illustrate the technical solution of the present invention, rather than to limit the protection scope of the present invention. Any simple modification or equivalent replacement of the technical solution of the present invention by those of ordinary skill in the art shall not depart from the essence and scope of the technical solution of the present invention.

Claims

1. A method for resource treatment of epichlorohydrin wastewater using ultraviolet light, characterized in that: It includes the following steps: S1: Fill a fixed-bed reactor with a catalyst, and under the irradiation of an ultraviolet lamp, introduce epichlorohydrin wastewater into the fixed-bed reactor for photocatalytic reaction; S2: Remove methanol from the wastewater treated by the fixed-bed reactor under negative pressure; S3: Introduce the methanol-removed wastewater into a resin adsorption column. After the resin is saturated with adsorption, desorption and regeneration are carried out to obtain crude glycerol; The source of the epichlorohydrin wastewater is the wastewater after methanol removal from the water layer in the hydrogen peroxide method epichlorohydrin process. The epichlorohydrin wastewater contains 0.05 - 0.07% of glycerol monomethyl ether, 0.15 - 0.23% of glycerol dimethyl ether, and the TOC is 4000 - 7000 mg / L; The catalyst is a nano-bismuth trioxide catalyst supported on ZSM-5 molecular sieve, and the resin is XDA macroporous adsorption resin.

2. The method for treating epichlorohydrin wastewater by using ultraviolet light resource treatment according to claim 1, wherein: The nano-bismuth trioxide catalyst supported on ZSM-5 molecular sieve is prepared by the following method: Immerse spherical ZSM-5 molecular sieve with a particle size of 2 - 5 mm in a dilute nitric acid solution, add Bi(NO3)3·5H2O, stir and mix, and ultrasonically disperse for 24 h. After drying, calcine at 550 °C for 3 h to obtain the nano-bismuth trioxide catalyst supported on ZSM-5 molecular sieve.

3. The method for treating epichlorohydrin wastewater by using ultraviolet light resource treatment according to claim 2, characterized in that: For the nano-bismuth trioxide catalyst supported on ZSM-5 molecular sieve, the loading amount of nano-bismuth trioxide is 0.1% - 1%.

4. The method for treating epichlorohydrin wastewater by using ultraviolet light resource treatment according to claim 3, wherein: In S1, the ultraviolet light source is a mercury lamp, and its power is set at 2000 - 20000 W per cubic meter of the fixed bed.

5. The method for treating epichlorohydrin wastewater by using ultraviolet light resource treatment according to claim 4, characterized in that: In S1, the fixed-bed reactor is made of a light-transmitting material, and the ultraviolet light source is arranged outside the fixed-bed reactor.

6. The method for treating epichlorohydrin wastewater by using ultraviolet light resource treatment according to claim 4, characterized in that: In S1, the fixed-bed reactor is made of an opaque material, and the ultraviolet light source is arranged inside the fixed-bed reactor.

7. The method for treating epichlorohydrin wastewater by using ultraviolet light resource treatment according to claim 5 or 6, characterized in that: In S1, the temperature of the photocatalytic reaction is 60 - 80 °C.

8. The method for treating epichlorohydrin wastewater by using ultraviolet light resource treatment according to claim 7, characterized in that: In S2, the conditions for removing methanol under negative pressure are 50 - 55 °C and the pressure is -0.085 MPa - -0.090 MPa.

9. The method for treating epichlorohydrin wastewater by using ultraviolet light resource treatment according to claim 8, characterized in that: In S3, the filling rate of the resin in the resin adsorption column is 90%. The XDA macroporous adsorption resin is saturated with adsorption after adsorbing 30 BV. The saturated XDA macroporous adsorption resin is desorbed and regenerated with steam at 105 - 110 °C to obtain crude glycerol.