A resource treatment process and application for high-concentration acetonitrile waste liquid in the field of chromatography

Abstract

The present application discloses a resource treatment process and application for high-concentration acetonitrile waste liquid in the field of preparative chromatography, belonging to the technical field of wastewater treatment in the environmental protection industry. The treatment process includes the following steps: After the waste liquid is adjusted in pH and filtered, it enters the solvent recovery unit, and more than 99% of the acetonitrile in the waste liquid is recovered into the distillate; the residual liquid after acetonitrile recovery is treated by the deep treatment unit and can meet the sewage discharge standard into the sewer with the acetonitrile content < 0.5 mg / L. The solvent recovery unit consists of a two-stage distillation system, and the deep treatment unit takes catalytic oxidation technology as the core. The entire process system not only realizes the recycling of acetonitrile in the high-concentration acetonitrile waste liquid but also realizes the up-to-standard treatment of the residual liquid, having good economic and environmental benefits.

Description

Technical Field

[0001] The present application relates to a resource treatment process and application for high-concentration acetonitrile waste liquid in the field of preparative chromatography, belonging to the technical field of wastewater treatment in the environmental protection industry. Background Art

[0002] Acetonitrile, with the chemical formula CH3CN, is a colorless and transparent liquid. It has the characteristics of high transparency, good solubility, low UV background absorption, and excellent solvent properties. It has a wide range of applications in the fields of organic synthesis, medicine, textile, analysis, etc. Acetonitrile is often used as a solvent in the field of preparative chromatography for the separation and purification of high-purity drugs, but at the same time, a large amount of acetonitrile waste liquid will be generated.

[0003] The high-concentration acetonitrile waste liquid generated by preparative chromatography has a high water content and also contains a small amount of impurities such as inorganic salts, organic acids, and proteins. It is difficult to treat and has strong environmental hazards. For high-concentration acetonitrile waste liquid, enterprises in the industry generally entrust professional hazardous waste treatment institutions for disposal, which not only has high costs but also causes waste of resources. Some enterprises in the industry use the rectification method to recover acetonitrile, which has problems such as high energy consumption and the need for further treatment of acetonitrile residue. Hazardous waste treatment enterprises generally use the incineration method to treat high-concentration waste liquid. Incineration treatment has high energy consumption and there are risks of secondary pollution such as nitrogen oxides and dioxins. Therefore, for the high-concentration acetonitrile waste liquid generated in the current preparative chromatography field, developing an economical and effective resource treatment process is of great significance. Summary of the Invention

[0004] In order to solve the above-mentioned technical problems, the present application provides a general technical solution of the "acetonitrile reuse + up-to-standard discharge" process for high-concentration acetonitrile waste liquid generated in the field of preparative chromatography. The recovery and utilization of acetonitrile in the acetonitrile waste liquid are realized through two-stage distillation in the solvent recovery unit, and the treatment of the acetonitrile residue to meet the discharge standards is realized through the deep treatment unit. The insoluble substances in the acetonitrile waste liquid are discharged in solid form. A resource treatment process for high-concentration acetonitrile waste liquid in the field of preparative chromatography is formed, realizing the reuse of acetonitrile in high-concentration acetonitrile waste liquid and the deep treatment of the residue, with low treatment cost and good effect.

[0005] The present application adopts the following technical solutions:

[0006] According to the first aspect of the present application, a resource treatment process for high-concentration acetonitrile waste liquid in the field of preparative chromatography is provided, and the resource treatment process is carried out in a treatment system;

[0007] The treatment system includes a water inlet preparation unit, a filtration unit, a solvent recovery unit, a deep treatment unit, and a drainage preparation unit that are connected in sequence;

[0008] Among them, the solvent recovery unit includes a primary distillation system for separating the acetonitrile recovery liquid and a secondary distillation system for separating the acetonitrile residue liquid;

[0009] The resource treatment process includes the following steps:

[0010] S1. Feed the acetonitrile waste liquid into the influent preparation unit, and adjust the pH value of the acetonitrile waste liquid to neutral in the influent preparation unit;

[0011] S2. Feed the acetonitrile waste liquid with adjusted pH value into the filtration unit, and filter out the suspended particulate matter in the filtration unit;

[0012] S3. Feed the acetonitrile waste liquid from which the suspended particulate matter has been filtered out into the solvent recovery unit, and respectively obtain the acetonitrile recovery liquid and the acetonitrile residue liquid through two-stage distillation in the solvent recovery unit. The acetonitrile recovery liquid is recycled for production;

[0013] S4. Feed the acetonitrile residue liquid into the advanced treatment unit, and perform catalytic oxidation treatment on the acetonitrile residue liquid in the advanced treatment unit to obtain;

[0014] S5. Feed the acetonitrile residue liquid after catalytic oxidation treatment into the effluent preparation unit, and adjust the pH to meet the discharge standard and then discharge it in the effluent preparation unit.

[0015] Optionally, in step S3, the process of two-stage distillation includes: the operating temperature of the primary distillation system is 50.0 °C to 99.5 °C, more than 98% of the acetonitrile in the acetonitrile waste liquid is recovered into the distillate to obtain the acetonitrile recovery liquid, and the bottom residue enters the secondary distillation system; the operating temperature of the secondary distillation system is 99.5 °C to 103 °C, and the bottom residue obtained from the primary distillation system is continuously distilled to obtain the acetonitrile residue liquid.

[0016] The above operating temperature is the actual operating temperature range. During the distillation process, as the fraction composition changes, the temperature of the distillate will change.

[0017] Optionally, in step S4, the volume of the acetonitrile recovery liquid is 39% - 44% of the acetonitrile waste liquid, and the volume of the acetonitrile residue liquid is 56% - 61% of the acetonitrile waste liquid.

[0018] Optionally, in step S4, the method of catalytic oxidation treatment is selected from at least one of the catalytic hydrogen peroxide oxidation process, the catalytic ozone oxidation process, and the electrocatalytic oxidation process.

[0019] Optionally, the conditions of the catalytic hydrogen peroxide oxidation process are: the dosage of H2O2 is mH2O2:mTOC = 1 - 18, the temperature is 40 °C - 120 °C, the pressure is 0 - 1.0 MPa, and the volume space velocity of the wastewater is 0.5 h -1 ~6 h -1 , and the influent pH is 2 - 7.

[0020] Optionally, the conditions of the catalytic ozonation process are as follows: the dosage of O3 is mO3:mTOC = 2.6 - 7.8, the temperature is 30°C - 50°C, the volume hourly space velocity of the wastewater is 0.5 h -1 ~6 h -1 , and the influent pH is 2 - 7.

[0021] Optionally, the conditions of the electrocatalytic oxidation process are as follows: the dosage of sodium chloride is 0 - 2 wt.%, the constant current is 1 A - 3 A, the current density is 20 mA / cm² - 60 mA / cm², the reaction time is 2 h - 6 h, the positive and negative electrodes are ruthenium-titanium coated electrodes or titanium suboxide coated electrodes, and the influent pH is 2 - 7.

[0022] Optionally, in step S1, the TOC of the acetonitrile waste liquid is 70,000 mg / L - 160,000 mg / L;

[0023] The concentration of acetonitrile in the acetonitrile waste liquid is 120 g / L - 280 g / L.

[0024] Optionally, in step S3, the TOC of the acetonitrile recovery liquid is 200,000 mg / L - 350,000 mg / L, and the concentration of acetonitrile in the acetonitrile recovery liquid is 350 g / L - 600 g / L.

[0025] According to another aspect of the present application, there is provided an application of the above-mentioned resource treatment process for high-concentration acetonitrile waste liquid in the field of preparative chromatography in the industrial recycling of high-concentration acetonitrile waste liquid, including the following process: conducting experiments on the target high-concentration acetonitrile waste liquid through the resource treatment process to obtain and determine the required parameters of the treatment process;

[0026] Selecting and customizing industrial equipment according to the parameters.

[0027] The beneficial effects of the present application include:

[0028] The resource treatment process for high-concentration acetonitrile waste liquid provided by the present application realizes the recovery of more than 99% of acetonitrile in the high-concentration acetonitrile waste liquid through two-stage distillation; through in-depth treatment, the acetonitrile content in the residual liquid is reduced to less than 0.5 mg / L, and other indicators meet the discharge requirements; the entire treatment process not only realizes the recycling of acetonitrile in the high-concentration acetonitrile waste liquid, but also realizes the up-to-standard treatment of the residual liquid, with good economic and environmental benefits and no secondary pollution. Description of the Drawings

[0029] Figure 1 It is a process flow diagram of the resource treatment process for high-concentration acetonitrile waste liquid of the present application. Detailed Description of the Embodiments

[0030] The present application will be described in detail below with reference to the embodiments, but the present application is not limited to these embodiments.

[0031] Unless otherwise specified, the raw materials in the embodiments of this application are all purchased through commercial channels.

[0032] Unless otherwise specified, the test methods are all conventional methods, and the instrument settings are all the settings recommended by the manufacturers.

[0033] TOC (Total Organic Carbon) is measured using a TOC-V analyzer produced by Shimadzu Corporation of Japan; CPH / CPN for the determination;

[0034] pH is measured using a Leici PHS-3C precision pH meter;

[0035] The acetonitrile content is measured using a GC-2100 gas chromatograph, equipped with an FID detector and an FFAP chromatographic column (30 m × 0.32 mm × 0.25 μm) for detection. The inlet temperature is 200 °C, the carrier gas flow rate is 2.0 mL / min, the injection volume is 1.0 μL, the split ratio is 10:1, the FID is 250 °C, the column temperature is maintained at 60 °C for 1 min, the heating rate is 8 °C / min, the air flow rate is 450 mL / min, and the hydrogen flow rate is 45 mL / min.

[0036] SS (Suspended Solids) is measured according to "GB 11901-89 Water Quality - Determination of Suspended Solids - Gravimetric Method".

[0037] A small-scale test device built in the laboratory is used to conduct experiments on each unit of formulation, filtration, solvent recovery, and advanced treatment. The small-scale test device involved can be built, commercially purchased, or customized by those skilled in the art according to needs, as long as the following process conditions can be achieved: The solvent recovery unit consists of a two-stage distillation system. The operating temperature of the first-stage distillation system is 50.0 °C to 99.5 °C, and more than 98% of the acetonitrile in the acetonitrile waste liquid is recovered into the distillate to obtain an acetonitrile recovery liquid, and the bottom residue enters the second-stage distillation system; the operating temperature of the second-stage distillation system is 99.5 °C to 103.0 °C, and the bottom residue obtained from the first-stage distillation system is further distilled to obtain an acetonitrile residue. The volume of the acetonitrile recovery liquid is 39% - 44% of the acetonitrile waste liquid, and the volume of the acetonitrile residue is 56% - 61% of the acetonitrile waste liquid. The advanced treatment unit adopts a catalytic oxidation process. The conditions for catalytic hydrogen peroxide oxidation are that the dosage of H2O2 is mH2O2:mTOC = 1 - 18, the temperature is 40 °C to 150 °C, the pressure is 0 - 1.0 MPa, and the volumetric space velocity of the wastewater is 0.5 h -1 ~6 h -1 . The conditions for catalytic ozone oxidation are: the dosage of O3 is mO3:mTOC = 2.6 - 7.8, the temperature is 30 - 50 °C, and the volumetric space velocity of the wastewater is 0.5 h -1 ~6 h -1. The electrocatalytic conditions are as follows: the addition amount of sodium chloride is 0 to 2 wt.%, the constant current is 1 A to 3 A, the current density is 20 mA / cm² to 60 mA / cm², the reaction time is 2 h to 6 h, and the positive and negative electrodes are ruthenium-titanium coated electrodes or titanium suboxide coated electrodes.

[0038] In the examples of this application, the acetonitrile waste liquid used is taken from the actual waste liquid generated by a preparative chromatography enterprise. According to the water quality differences, the samples are marked as Sample 1, Sample 2, and Sample 3. The specific water quality is shown in Table 1:

[0039] Table 1 Acetonitrile waste liquid

[0040]

[0041] Example 1 Resource treatment system and process for high-concentration acetonitrile waste liquid in the field of preparative chromatography

[0042] The resource treatment system for high-concentration acetonitrile waste liquid in the field of preparative chromatography is as Figure 1 shown. The system includes a water inlet adjustment unit, a filtration unit, a solvent recovery unit, a deep treatment unit, and a drainage adjustment unit that are connected in sequence;

[0043] The water inlet adjustment unit is used to adjust the pH value of the acetonitrile waste liquid;

[0044] The filtration unit is used to filter out the suspended particles in the acetonitrile waste liquid, generating a small amount of solid residues;

[0045] The solvent recovery and treatment unit is used to separate the acetonitrile waste liquid, and specifically consists of a two-stage distillation system: the first-stage distillation system is used to recover more than 98% of the acetonitrile in the acetonitrile waste liquid into the distillate to obtain an acetonitrile recovery liquid; the second-stage distillation system is used to continue distilling the residue obtained from the first-stage distillation system to obtain an acetonitrile residue, and a small amount of solid residues are generated during the second-stage distillation process.

[0046] The deep treatment unit is used to treat the acetonitrile waste liquid by using catalytic oxidation technology, and the catalytic oxidation technology adopts at least one of catalytic hydrogen peroxide oxidation process, catalytic ozone oxidation process, and electrocatalytic oxidation process.

[0047] The drainage adjustment unit is used to adjust the pH value of the residue after being treated by the deep treatment unit to meet the discharge standard.

[0048] The resource treatment process for high-concentration acetonitrile waste liquid in the field of preparative chromatography realized by using the above system is as Figure 1 shown. The specific treatment process steps are as follows:

[0049] (1) The acetonitrile waste liquid enters the water inlet adjustment unit, and the pH is adjusted to neutral by an alkaline solution;

[0050] (2) The acetonitrile waste liquid after pH adjustment enters the filtration unit, and the suspended particles are removed;

[0051] (3) The filtered acetonitrile waste liquid enters the solvent recovery unit, and after being treated by a two-stage distillation system, acetonitrile recovery liquid and acetonitrile residue liquid are obtained respectively;

[0052] (4) The acetonitrile recovery liquid is recycled for production, and the acetonitrile residue liquid enters the advanced treatment unit, and the pollutants are treated to below the discharge limit value;

[0053] (5) The acetonitrile recovery liquid after advanced treatment enters the drainage adjustment unit, and the pH is adjusted to neutral with acid solution or alkali solution to meet the direct discharge standard.

[0054] Using the above-mentioned resource treatment process for high-concentration acetonitrile waste liquid in the field of preparative chromatography, the resource treatment processes are carried out on the acetonitrile waste liquid samples in Table 1 respectively. The specific process steps, process conditions and effluent water quality results in each treatment unit are as follows:

[0055] (1) Blending unit

[0056] The pH of the acetonitrile waste liquid is adjusted to about 7.0 with liquid caustic soda and then transported to the filtration unit. The effluent water quality is shown in Table 2.

[0057] Table 2

[0058]

[0059] (2) Filtration unit

[0060] The SS in the adjusted acetonitrile waste liquid is removed through the filtration unit and then transported to the solvent recovery unit. The effluent water quality is shown in Table 3.

[0061] Table 3

[0062]

[0063] (3) Solvent recovery unit

[0064] The solvent recovery unit adopts a two-stage distillation system. The operating temperature of the first-stage distillation system is 50.0 °C to 99.5 °C, and more than 98% of the acetonitrile in the acetonitrile waste liquid is recovered into the distillate to obtain the acetonitrile recovery liquid, and the bottom residue enters the second-stage distillation system; the operating temperature of the second-stage distillation system is 99.5 °C to 103.0 °C, and the bottom residue obtained from the first-stage distillation system is continuously distilled, and the distillate obtained is the acetonitrile residue liquid. After testing, after the samples 1-3 are treated by the solvent recovery unit, the volume of the acetonitrile recovery liquid is 39% - 44% of the acetonitrile waste liquid, and the volume of the acetonitrile residue liquid is 56% - 61% of the acetonitrile waste liquid. The effluent water quality is shown in Tables 4 and 5.

[0065] Table 4 Acetonitrile recovery liquid

[0066]

[0067] Table 5 Acetonitrile Residual Liquid

[0068]

[0069] (4)Advanced Treatment Unit

[0070] ① When the advanced treatment adopts the catalytic hydrogen peroxide oxidation process, the reaction conditions are: the dosage of H2O2 is m H2O2:mTOC = 6, the temperature is 50°C, the pressure is normal pressure, and the volume space velocity of the wastewater is 1.0 h -1 . The effluent quality is shown in Table 6

[0071] Table 6

[0072]

[0073] ② When the advanced treatment adopts the catalytic ozone oxidation process, the reaction conditions are: the dosage of O3 is m O3:m TOC = 4.0, the temperature is 40°C, and the volume space velocity of the wastewater is 1.0 h -1 . The effluent quality is shown in Table 7

[0074] Table 7

[0075]

[0076] ③ When the advanced treatment adopts the electro-catalytic oxidation process, the reaction conditions are: the addition amount of sodium chloride is 0.3 wt.%, the constant current is 2 A, the current density is 40 mA / cm², the reaction time is 3 h, and the positive and negative electrodes are ruthenium-titanium coated electrodes. The effluent quality is shown in Table 8

[0077] Table 8

[0078]

[0079] ④ When the advanced treatment adopts the combined process of catalytic hydrogen peroxide oxidation and catalytic ozone oxidation, the reaction conditions are: the dosage of H2O2 is m H2O2:m TOC = 3, the dosage of O3 is m O3:m TOC = 2.0, the temperature is 40°C, and the volume space velocity of the wastewater is 1.0 h -1 . The effluent quality is shown in Table 9

[0080] Table 9

[0081]

[0082] ⑤ When the advanced treatment adopts the combined process of catalytic hydrogen peroxide oxidation and electrocatalytic oxidation, the reaction conditions are as follows: the dosage of H2O2 is m H2O2: m TOC = 3; the addition amount of sodium chloride is 0.3 wt.%, constant current of 1 A, current density of 20 mA / cm², the positive and negative electrodes are ruthenium-titanium coated electrodes, the temperature is 40 °C, and the volume space velocity of the wastewater is 1.0 h -1 The effluent quality is shown in Table 10.

[0083] Table 10

[0084]

[0085] The proposed resource treatment process of this application was used to conduct experiments on three actual acetonitrile waste liquids, namely Sample 1, Sample 2, and Sample 3. The results show that: the process route developed in this application can not only achieve the recovery of acetonitrile in the acetonitrile waste liquid, but also the acetonitrile residue can meet the discharge requirements after advanced treatment. The treatment process was determined through the above experiments, and then the industrial equipment for the resource treatment process of high-concentration acetonitrile waste liquid was selected and customized according to the process parameters.

[0086] The above are only several embodiments of this application, and do not impose any form of limitation on this application. Although this application is disclosed above with preferred embodiments, it is not intended to limit this application. Any person skilled in the art, without departing from the technical solution of this application, makes some changes or modifications using the disclosed technical content, which are equivalent to equivalent implementation cases and all fall within the scope of the technical solution.

Claims

1. A resource treatment process for high-concentration acetonitrile waste liquid in the field of preparative chromatography, characterized in that: The resource recovery process is carried out in a processing system; The treatment system comprises a water inlet preparation unit, a filtration unit, a solvent recovery unit, a deep treatment unit, and a drainage preparation unit which are connected in sequence; Wherein, the solvent recovery unit includes a primary distillation system for separating acetonitrile recovery liquid and a secondary distillation system for separating acetonitrile residual liquid; The resource recovery process comprises the following steps: S1, passing the acetonitrile waste liquid into an inlet water preparation unit, and adjusting the pH value of the acetonitrile waste liquid to be neutral in the inlet water preparation unit; S2, passing the acetonitrile waste liquid after adjusting the pH value into a filtration unit, and filtering out suspended particles in the filtration unit; S3, passing the acetonitrile waste liquid from which suspended particles are filtered out into a solvent recovery unit, and performing two-stage distillation in the solvent recovery unit to obtain acetonitrile recovery liquid and acetonitrile residual liquid, respectively, and the acetonitrile recovery liquid is reused for production; S4, passing the acetonitrile residual liquid into a deep processing unit, and performing catalytic oxidation treatment on the acetonitrile residual liquid in the deep processing unit; S5, passing the acetonitrile residual liquid after catalytic oxidation treatment into a drainage preparation unit, adjusting the pH in the drainage preparation unit to meet the discharge standard before discharging; In step S3, the two-stage distillation process includes: the operating temperature of the primary distillation system is 50.0°C to 99.5°C, more than 98% of the acetonitrile in the acetonitrile waste liquid is recovered into the distillate to obtain acetonitrile recovery liquid, and the kettle residue enters the secondary distillation system; the operating temperature of the secondary distillation system is 99.5°C to 103°C, the kettle residue obtained by the primary distillation system is further distilled to obtain acetonitrile residue, the volume of the acetonitrile recovery liquid is 39% to 44% of the acetonitrile waste liquid, and the volume of the acetonitrile residue is 56% to 61% of the acetonitrile waste liquid; In step S4, the catalytic oxidation treatment method is selected from at least one of a catalytic hydrogen peroxide oxidation process, a catalytic ozone oxidation process, and an electrocatalytic oxidation process; The conditions of the catalytic hydrogen peroxide oxidation process are: H2O2 dosage is mH2O2:mTOC=1~18, temperature is 40℃~120℃, pressure is 0~1.0MPa, and the volume space velocity of wastewater is 0.5h -1 ~6h -1 , the inlet water pH is 2~7; The conditions of the catalytic ozone oxidation process are: O3 dosage is mO3:mTOC=2.6~7.8, temperature is 30℃~50℃, volume space velocity of wastewater is 0.5h -1 ~6h -1 , the inlet water pH is 2~7; The conditions of the electrocatalytic oxidation process are as follows: the amount of sodium chloride added is 0~2wt.%, the constant current is 1~3A, the current density is 20mA / cm²~60mA / cm², the reaction time is 2h~6h, the positive and negative electrodes are ruthenium titanium coated electrodes or sub-titanium oxide coated electrodes, and the inlet water pH is 2~7.

2. The resource processing process for high-concentration acetonitrile waste liquid in the preparative chromatography field according to claim 1, characterized in that, In step S1, the TOC of the acetonitrile waste liquid is 70,000 mg / L to 160,000 mg / L; The acetonitrile concentration in the acetonitrile waste liquid is 120g / L~280g / L.

3. The resource processing process for high-concentration acetonitrile waste liquid in the preparative chromatography field according to claim 1, characterized in that, In step S3, the TOC of the acetonitrile recovery liquid is 200,000 mg / L to 350,000 mg / L, and the acetonitrile concentration in the acetonitrile recovery liquid is 350 g / L to 600 g / L.

4. The resource treatment process for high-concentration acetonitrile waste liquid in the preparative chromatography field according to any one of claims 1 to 3 is applied in industrial recycling of high-concentration acetonitrile waste liquid, characterized in that: The method comprises the following steps: conducting experiments on target high-concentration acetonitrile waste liquid through the resource recovery treatment process to obtain and determine the required parameters of the treatment process; The industrial equipment is selected and customized according to the said parameters.

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