Method for treating wastewater in chlorobenzene production process

Abstract

The invention discloses a method for treating wastewater in a chlorobenzene production process, and belongs to the technical field of wastewater treatment. The wastewater treatment method specifically relates to a method for adsorbing and treating chlorobenzene production wastewater containing benzene and chlorobenzene by using hydrophobic modified activated carbon as an adsorbent. According to the method, the activated carbon is subjected to hydrophobic modification, so that the adsorption effect of the activated carbon on non-polar benzene and chlorobenzene can be improved; and the activated carbon is desorbed by using a microwave technology, so that the activated carbon can be quickly regenerated. The content of benzene and the content of chlorobenzene in the treated chlorobenzene wastewater both reach the first-grade discharge standard.

Description

Technical Field

[0001] The invention relates to the technical field of wastewater treatment, and in particular to a method for treating wastewater in a chlorobenzene production process. Background Art

[0002] Chlorobenzene is an important basic organic synthesis raw material, used as dyes, medicines, pesticides, and organic synthesis intermediates. The industrial production mainly adopts the benzene liquid phase chlorination method, and the tower boiling continuous chlorination process is widely used in China. The wastewater generated in the production process of chlorobenzene mainly includes acidic wastewater, alkaline wastewater and other wastewater. The mixed wastewater has Cl - It has the characteristics of high ion concentration, strong acidity, deep color and high toxicity. If it is directly discharged into the sewage treatment plant for treatment, it will have a serious toxic effect on the microorganisms in the sewage treatment plant and greatly affect the degradation rate of pollutants. Common methods for treating chlorinated benzene wastewater include stripping, adsorption, chemical treatment, biological treatment and other methods. Although the wastewater after stripping treatment can meet the requirements of biochemical treatment, it still contains a lot of benzene and chlorinated benzene.

[0003] Benzene is a colorless, sweet, transparent liquid with a strong aromatic smell at room temperature. Benzene is flammable, toxic, and a carcinogen. Chlorobenzene has a strong odor and can irritate the respiratory tract, skin, and mucous membranes. It can accumulate in the human body, damage the liver, kidneys, immune system, and nervous system, and has obvious "tri-toxic effects". Due to the high toxicity and difficulty in biodegradation of benzene and chlorobenzene, many countries have classified them as priority controlled pollutants. my country's Comprehensive Wastewater Discharge Standard (GB8978-1996) also has clear requirements for benzene and chlorobenzene. Among them, the primary emission standard for benzene is 0.1mg / L; the primary emission standard for chlorobenzene is 0.2mg / L. Summary of the invention

[0004] In order to overcome the deficiencies of the prior art, the object of the present invention is to provide a method for treating wastewater in the production process of chlorobenzene, so as to solve the technical problem that benzene and chlorobenzene are difficult to remove in the wastewater of chlorobenzene production.

[0005] The purpose of the present invention can be achieved through the following technical solutions:

[0006] A method for treating wastewater in a chlorobenzene production process comprises the following steps:

[0007] S1. preparing hydrophobically modified activated carbon as an adsorbent;

[0008] S2. Adsorption: using hydrophobic modified activated carbon to adsorb wastewater;

[0009] S3, adsorbent desorption: subjecting the used hydrophobic modified activated carbon to microwave treatment to obtain regenerated hydrophobic modified activated carbon;

[0010] The hydrophobically modified activated carbon is polydimethylsiloxane-modified activated carbon.

[0011] Further, S1, the specific steps of preparing hydrophobically modified activated carbon as an adsorbent are:

[0012] The polydimethylsiloxane and the curing agent are mixed to obtain the fluid PDMS; the fluid PDMS is placed in a glass chamber and covered with a mesh partition, and the activated carbon is spread on the mesh partition; the glass chamber is sealed and then placed in a heating furnace; the chamber is heated to 200° C. and maintained for 1-2 hours to obtain the hydrophobically modified activated carbon.

[0013] Furthermore, the curing agent is one of Sylgard 184 and Sylgard 186.

[0014] Furthermore, the mass ratio of polydimethylsiloxane to the curing agent is 10:1.

[0015] Furthermore, the mass ratio of polydimethylsiloxane to activated carbon in the fluid PDMS is 80-100:1.

[0016] Further, the specific steps of S2, adsorption are:

[0017] The wastewater was heated and passed through the hydrophobically modified activated carbon at a flow rate of 1 mL / min for adsorption treatment for 2-4 hours.

[0018] Furthermore, the wastewater is wastewater after stripping treatment, the benzene content in the wastewater is 20-40 mg / L, and the chlorinated benzene content is 40-60 mg / L.

[0019] Furthermore, the wastewater heating temperature is 70-80°C.

[0020] Furthermore, the hydrophobically modified activated carbon accounts for 8-10% of the wastewater mass.

[0021] Furthermore, the power of the microwave treatment in S3 is 550-650 W, and the treatment time is 5-10 min.

[0022] Beneficial effects of the present invention:

[0023] (1) The surface of activated carbon has abundant polar sites, and it will give priority to adsorbing water molecules when adsorbing benzene and chlorobenzene in wastewater. Water molecules can also be adsorbed on the polar groups on the surface of activated carbon through hydrogen bonding. Excessive accumulation of water molecules may form large-sized water clusters, which seriously hinder the contact between benzene and chlorobenzene molecules and the surface of activated carbon. The present invention uses polydimethylsiloxane to hydrophobically modify activated carbon, which can significantly improve the adsorption effect of activated carbon on non-polar benzene and chlorobenzene. The contents of benzene and chlorobenzene in the treated chlorobenzene wastewater reach the first-level emission standard of the comprehensive sewage discharge standard.

[0024] (2) The present invention uses microwave technology to adsorb and desorb hydrophobic modified activated carbon to obtain regenerated hydrophobic modified activated carbon, which still has excellent adsorption effect when reused; compared with conventional thermal treatment desorption, microwave technology can achieve the purpose of rapid regeneration. DETAILED DESCRIPTION

[0025] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0026] Example 1

[0027] This embodiment provides a method for treating wastewater in a chlorobenzene production process, comprising the following steps:

[0028] S1. Preparation of hydrophobically modified activated carbon as adsorbent:

[0029] Polydimethylsiloxane and Sylgard 184 curing agent are mixed in a mass ratio of 10:1 to obtain fluid PDMS; the fluid PDMS is placed in a glass chamber and covered with a mesh partition, and activated carbon is spread on the mesh partition; the mass ratio of polydimethylsiloxane to activated carbon in the fluid PDMS is 80:1; the glass chamber is sealed and then placed in a heating furnace; it is heated to 200°C and maintained for 1 hour to obtain hydrophobically modified activated carbon, which is recorded as PDMS / AC.

[0030] S2. Adsorption: 200 g of wastewater after stripping treatment, in which the benzene content was 29.1 mg / L and the chlorobenzene content was 43.2 mg / L, was heated to 75°C and passed through 16 g of PDMS / AC at a flow rate of 1 mL / min for 3 h of adsorption treatment.

[0031] S3. Adsorbent desorption: The used PDMS / AC was subjected to microwave treatment at 600 W for 10 min to obtain regenerated hydrophobic modified activated carbon, thereby obtaining regenerated PDMS / AC.

[0032] Example 2

[0033] Compared with Example 1, the difference between this embodiment is that the "mass ratio of polydimethylsiloxane to activated carbon in the fluid PDMS is 80:1" in step S1 is changed to "the mass ratio of polydimethylsiloxane to activated carbon in the fluid PDMS is 90:1"; the other raw materials and preparation process remain the same as in Example 1.

[0034] Example 3

[0035] Compared with Example 1, the difference between this embodiment is that the "mass ratio of polydimethylsiloxane to activated carbon in the fluid PDMS is 80:1" in step S1 is changed to "the mass ratio of polydimethylsiloxane to activated carbon in the fluid PDMS is 100:1"; the other raw materials and preparation process remain the same as in Example 1.

[0036] Example 4

[0037] Compared with Example 3, the difference between this example is that the "passing 16 g PDMS / AC at a flow rate of 1 mL / min" in step S2 is changed to "passing 18 g PDMS / AC at a flow rate of 1 mL / min"; the remaining raw materials and preparation process remain the same as in Example 3.

[0038] Example 5

[0039] Compared with Example 3, the difference between this example is that the "passing 16 g PDMS / AC at a flow rate of 1 mL / min" in step S2 is changed to "passing 20 g PDMS / AC at a flow rate of 1 mL / min"; the remaining raw materials and preparation process remain the same as in Example 3.

[0040] Comparative Example 1

[0041] The difference between this comparative example and Example 1 is that activated carbon that has not been hydrophobically modified is used to adsorb wastewater; the remaining raw materials and preparation process remain the same as those in Example 1.

[0042] The wastewater after adsorption treatment in Examples 1 to 5 and Comparative Example 1 was sampled and analyzed to obtain the benzene content and chlorobenzene content in the wastewater after adsorption treatment. The results are shown in Table 1.

[0043] Table 1

[0044]

[0045]

[0046] As can be seen from Table 1, the contents of benzene and chlorobenzene in the wastewater treated in Examples 1 to 5 all reach the first-level discharge standard of the comprehensive sewage discharge standard. Compared with Examples 1 to 3, increasing the amount of polydimethylsiloxane in PDMS / AC is beneficial to enhancing the adsorption effect of the adsorbent; compared with Examples 3 to 5, increasing the amount of adsorbent is beneficial to improving the adsorption effect; compared with Example 1, Comparative Example 1 uses unmodified activated carbon as an adsorbent, and the adsorption effect is poor. The contents of benzene and chlorobenzene in the wastewater after treatment are still high and do not meet the comprehensive sewage discharge standard.

[0047] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device.

[0048] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for treating wastewater in a chlorobenzene production process, characterized in that: The steps include: S1. preparing hydrophobically modified activated carbon as an adsorbent; S2. Adsorption: using hydrophobic modified activated carbon to adsorb wastewater; S3, adsorbent desorption: subjecting the used hydrophobic modified activated carbon to microwave treatment to obtain regenerated hydrophobic modified activated carbon; The hydrophobically modified activated carbon is polydimethylsiloxane-modified activated carbon.

2. The method for treating wastewater in a chlorobenzene production process according to claim 1, characterized in that: Step S1 The specific steps of preparing hydrophobically modified activated carbon as an adsorbent are: The polydimethylsiloxane and the curing agent are mixed to obtain the fluid PDMS; the fluid PDMS is placed in a glass chamber and covered with a mesh partition, and the activated carbon is spread on the mesh partition; the glass chamber is sealed and then placed in a heating furnace; the chamber is heated to 200° C. and maintained for 1-2 hours to obtain the hydrophobically modified activated carbon.

3. The method for treating wastewater in a chlorobenzene production process according to claim 2, characterized in that: The curing agent is one of Sylgard 184 and Sylgard 186.

4. The method for treating wastewater in a chlorobenzene production process according to claim 2, characterized in that: The mass ratio of polydimethylsiloxane to curing agent is 10:

1.

5. The method for treating wastewater in a chlorobenzene production process according to claim 2, characterized in that: The mass ratio of polydimethylsiloxane to activated carbon in the fluid PDMS is 80-100:

1.

6. The method for treating wastewater in a chlorobenzene production process according to claim 1, characterized in that: The specific steps of step S2 adsorption are: The wastewater was heated and passed through the hydrophobically modified activated carbon at a flow rate of 1 mL / min for adsorption treatment for 2-4 hours.

7. The method for treating wastewater in a chlorobenzene production process according to claim 6, characterized in that: The wastewater is wastewater after stripping treatment, the benzene content in the wastewater is 20-40 mg / L, and the chlorobenzene content is 40-60 mg / L.

8. The method for treating wastewater in a chlorobenzene production process according to claim 6, characterized in that: The wastewater heating temperature is 70-80℃.

9. The method for treating wastewater in a chlorobenzene production process according to claim 6, characterized in that: Hydrophobically modified activated carbon accounts for 8-10% of the wastewater mass.

10. The method for treating wastewater in a chlorobenzene production process according to claim 1, characterized in that: The power of the microwave treatment in S3 is 550-650 W, and the treatment time is 5-10 min.

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