CN112827365A - Super-hydrophobic membrane, preparation method thereof and method for concentrating and recycling MDI waste brine - Google Patents

Super-hydrophobic membrane, preparation method thereof and method for concentrating and recycling MDI waste brine Download PDF

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CN112827365A
CN112827365A CN201911159196.8A CN201911159196A CN112827365A CN 112827365 A CN112827365 A CN 112827365A CN 201911159196 A CN201911159196 A CN 201911159196A CN 112827365 A CN112827365 A CN 112827365A
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membrane
treatment
brine
super
washing wastewater
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CN112827365B (en
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李永锋
邢津铭
吴雪峰
张宏科
范珍龙
高学顺
曾凡雪
崔成成
周波
赵义兵
李鹏
杨其林
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Wanhua Chemical Group Fujian Isocyanate Co ltd
Wanhua Chemical Group Co Ltd
Wanhua Chemical Ningbo Co Ltd
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Wanhua Chemical Group Co Ltd
Wanhua Chemical Ningbo Co Ltd
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D67/00—Processes specially adapted for manufacturing semi-permeable membranes for separation processes or apparatus
    • B01D67/0002—Organic membrane manufacture
    • B01D67/0009—Organic membrane manufacture by phase separation, sol-gel transition, evaporation or solvent quenching
    • B01D67/0011—Casting solutions therefor
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D67/00—Processes specially adapted for manufacturing semi-permeable membranes for separation processes or apparatus
    • B01D67/0002—Organic membrane manufacture
    • B01D67/0009—Organic membrane manufacture by phase separation, sol-gel transition, evaporation or solvent quenching
    • B01D67/0013—Casting processes
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D69/00—Semi-permeable membranes for separation processes or apparatus characterised by their form, structure or properties; Manufacturing processes specially adapted therefor
    • B01D69/02—Semi-permeable membranes for separation processes or apparatus characterised by their form, structure or properties; Manufacturing processes specially adapted therefor characterised by their properties
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00—Treatment of water, waste water, or sewage
    • C02F1/26—Treatment of water, waste water, or sewage by extraction
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00—Treatment of water, waste water, or sewage
    • C02F1/44—Treatment of water, waste water, or sewage by dialysis, osmosis or reverse osmosis
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F9/00—Multistage treatment of water, waste water or sewage
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2323/00—Details relating to membrane preparation
    • B01D2323/04—Hydrophobization
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2325/00—Details relating to properties of membranes
    • B01D2325/38—Hydrophobic membranes
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00—Treatment of water, waste water, or sewage
    • C02F1/02—Treatment of water, waste water, or sewage by heating
    • C02F1/04—Treatment of water, waste water, or sewage by heating by distillation or evaporation
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F2101/00—Nature of the contaminant
    • C02F2101/30—Organic compounds
    • C02F2101/38—Organic compounds containing nitrogen
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F3/00—Biological treatment of water, waste water, or sewage

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Hydrology & Water Resources (AREA)
  • Environmental & Geological Engineering (AREA)
  • Water Supply & Treatment (AREA)
  • Organic Chemistry (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Dispersion Chemistry (AREA)
  • Manufacturing & Machinery (AREA)
  • Separation Using Semi-Permeable Membranes (AREA)

Abstract

The invention belongs to the technical field of industrial waste brine treatment, and particularly relates to a super-hydrophobic membrane, a preparation method thereof and a method for concentrating and recycling MDI waste brine, wherein the method for concentrating and recycling the MDI waste brine comprises the following steps: 1) carrying out two-phase separation on MDI waste brine to generate an organic phase and a brine phase; 2) sequentially carrying out aniline extraction, reboiling distillation and TOC removal on a brine phase; 3) washing the organic phase to obtain washing wastewater; contacting the washing wastewater with an extracting agent to carry out membrane extraction treatment; conveying the water washing wastewater after membrane extraction treatment to a biochemical unit and then feeding the water washing wastewater into a reclaimed water recycling system. In the membrane extraction treatment, the washing wastewater to be treated passes through the super-hydrophobic membrane for extraction treatment. After the treatment by the method, high-concentration brine with the sodium chloride content of 21-25 wt% can be obtained, and the super-hydrophobic membrane is utilized to simplify the treatment process and avoid steam consumption in the washing wastewater treatment process.

Description

Super-hydrophobic membrane, preparation method thereof and method for concentrating and recycling MDI waste brine
Technical Field
The invention belongs to the technical field of industrial waste brine treatment, and particularly relates to a super-hydrophobic membrane suitable for extracting high-concentration organic amine wastewater, a preparation method thereof and a method for concentrating and recycling MDI waste brine.
Background
MDI is one of the main raw materials in the polyurethane industry. The synthesis of MDI by reacting aniline and formaldehyde in the presence of an acidic catalyst to produce polymethylene polyphenyl polyamines (DAM) and then reacting the DAM with phosgene is a well known process in the industry. In the process of preparing DAM from aniline and formaldehyde, reaction liquid obtained by reaction is neutralized by caustic soda, and a large amount of high-concentration brine is generated. Meanwhile, a small amount of salt is carried in the organic phase obtained after neutralization, and the organic phase needs to be further washed to remove the salt, so that the stable operation of the subsequent process and the stable and qualified quality of the DAM product are ensured.
In the traditional process, because the neutralized salt water after the neutralization treatment of the caustic soda and the washing wastewater obtained after the washing treatment have basically consistent organic matter compositions, the two are generally mixed together completely or partially for extraction, distillation and TOC removal treatment, and then the mixed water is recycled as the raw material of chlor-alkali or discharged to the sea.
For example, patent document CN200880107822.2 mentions a treatment process of combining neutralized brine with water-washed wastewater, followed by extraction and stripping. Patent document CN200980118981.7 mentions a process using toluene as solvent for extraction and stripping evaporation. However, in the above processes of mixing the neutralized brine and the water washing wastewater for subsequent treatment, since the brine content in the water washing wastewater is much lower than that of the neutralized brine, the salt concentration in the brine obtained after treatment is low, which not only limits the reuse amount of the downstream chlor-alkali plant and increases the discharge amount, but also requires further concentration of the brine in order to meet the reuse requirements, thereby increasing the energy consumption and increasing the cost.
Similarly, there are many well known methods for concentrating brine, such as multiple effect evaporation, MVR, etc. However, up to now, there has been no mention of a method of completely separating the neutralized brine from the water-washed wastewater from the inside of the process for producing DAM and separately treating both to realize complete resource utilization of wastewater in the DAM production process.
Therefore, it is urgently needed to develop a simple and efficient MDI waste brine concentration and treatment process from a process source so as to realize complete resource utilization of waste salt and waste water in the MDI production process.
Disclosure of Invention
The invention aims to provide a super-hydrophobic membrane, a preparation method thereof and a method for concentrating and recycling MDI waste brine aiming at the problems in the prior MDI waste brine concentration treatment process. After the treatment by the method, high-concentration brine with the sodium chloride of which the mass percentage is 21-25% can be obtained, and meanwhile, the super-hydrophobic membrane simplifies the process flow of the treatment and fundamentally avoids the steam consumption in the treatment process of the washing wastewater.
In order to achieve the purpose, the invention adopts the following technical scheme:
in one aspect, a method for preparing an ultrahydrophobic membrane for extracting high-concentration organic amine wastewater is provided, which comprises the following steps:
i. preparing a bionic template: uniformly coating an epoxy resin adhesive on a glass substrate, and uniformly paving micron-sized silicon carbide particles on the epoxy resin adhesive on the glass substrate; curing and baking the mixture, cooling and removing the silicon carbide particles which are not fixed on the surface of the epoxy resin adhesive to form a bionic template similar to a lotus leaf effect;
ii. Preparing a fluorosilicone rubber film with a rough surface: uniformly mixing liquid fluorosilicone rubber (FVMQ), a curing agent and a solvent to prepare a membrane casting solution, and then uniformly coating the obtained membrane casting solution on the surface of the bionic template; curing the film at room temperature to form a film, and then heating, drying and peeling the film to obtain a fluorosilicone rubber film (FVMQ film) with a rough surface;
iii, plasma surface treatment: carrying out plasma surface treatment on the fluorosilicone rubber membrane to obtain the fluorosilicone rubber membrane with increased membrane porosity;
iv, immersing the obtained fluorine silicon rubber membrane with increased membrane porosity into surface modification liquid for surface modification treatment; and then carrying out thermosetting treatment to obtain the super-hydrophobic film.
According to the preparation method provided by the present invention, preferably, in step i, the particle size of the micron-sized silicon carbide particles is 0.5-15 μm (e.g., 1 μm, 3 μm, 5 μm, 10 μm, 12 μm), and more preferably 2-8 μm.
In some examples, the epoxy adhesive is a medium temperature curing adhesive comprising: epoxy resin and curing agent a.
In some preferred embodiments, the epoxy resin is selected from one or more of bisphenol a type epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin, and bisphenol P type epoxy resin; the curing agent a is selected from one or more of dicyandiamide, diethylimidazole and methyl tetracyanophthalic anhydride.
In step i, for example, the prepared epoxy adhesive may be placed in an oven with a glass substrate covered with micron-sized silicon carbide particles, and the amount of silicon carbide is at least sufficient to completely cover the epoxy adhesive, i.e., the covering thickness should be at least 4mm higher than the surface height of the epoxy adhesive. In some examples, the conditions of the curing process include: the curing temperature is 90-110 deg.C (e.g., 100 deg.C, 105 deg.C), and the curing time is 50-80min (e.g., 60min, 70 min). In some examples, the conditions of the baking include: the baking temperature is 150-170 deg.C (e.g., 155 deg.C, 160 deg.C, 165 deg.C), and the baking time is 8-15min (e.g., 10min, 12 min).
Step i after baking, the surface of the biomimetic template may be cooled to 100 ℃ or below. Then, uniformly blowing the surface for 10-20min by using a device (such as a blower and the like) to remove the silicon carbide particles which are not fixed on the surface of the template.
Step i is to adopt the bionic template prepared by micron-sized silicon carbide particles, and the surface of the bionic template has a plurality of tiny mastoids which are close to the average diameter of the mastoids on the lotus leaf surface, so that the roughness of the surface of the bionic template is better.
According to the preparation method provided by the invention, in the step ii, in some examples, the curing agent is selected from at least one of vinyl triamine, dipropylene triamine and triethylene tetramine. In some examples, the solvent is acetone and/or ethanol. For example, the curing agent, the solvent and the liquid fluorosilicone rubber can be stirred for 0.5-1h at the rotating speed of 300r/min to prepare the casting solution.
In some preferred embodiments, the liquid fluorosilicone rubber: curing agent: the mass ratio of the solvent is 100 (5-8) to 15-30; for example, the mass ratio is 100:6:20, 100:6:25, 100:6.5: 28.
In step ii, after the casting solution is uniformly coated on the surface of the biomimetic template (i.e. coated on the side on which the silicon carbide particles are fixed), for example, the solvent in the bionic template can be naturally volatilized at room temperature (e.g. 25 ℃) to be cured into a film. In some examples, the time for curing to form a film at room temperature is 10-18h (e.g., 12h, 14h, 16 h).
In step ii, for example, the film cured at room temperature may be transferred to an oven to be dried by heating. In some examples, the conditions of the heat drying include: the temperature is 70-95 deg.C (e.g., 75 deg.C, 80 deg.C, 85 deg.C, 90 deg.C), and the time is 4-6h (e.g., 5 h). After drying in an oven, the film on the glass substrate was peeled off to obtain an FVMQ film having a rough surface.
Because the shapes of the silicon carbide particles are random, gaps with different shapes and sizes exist among the particles, when the surface of the bionic template which is fully covered with the silicon carbide particles is coated with the casting solution with certain viscosity, the casting solution can be filled in the gaps among the silicon carbide particles, and the silicon carbide particles are peeled off after being dried to obtain the film with the rough microstructure which is opposite to the shape of the template. And the preparation of the rough surface provides possibility for the super-hydrophobic property of the membrane.
In addition, the FVMQ material is selected and used, and is suitable for the working condition of extracting amine-containing organic wastewater by adopting acid due to good acid and alkali resistance, organic solvent resistance and the capability of resisting high temperature below 200 ℃.
According to the preparation method provided by the present invention, in the step iii, for example, the FVMQ film obtained in the step ii may be fixed on a support plate of a plasma surface treatment apparatus, a switch of the plasma surface treatment apparatus is turned on, a gas containing ammonia (for example, ammonia, a mixed gas of ammonia and nitrogen, or a mixed gas of ammonia and air) is introduced, parameters are set, and a plasma generator is operated to perform surface treatment.
In some preferred embodiments, the plasma surface treatment conditions include: a radio frequency power of 10-150W (e.g., 30W, 50W, 80W, 100W, 120W), a gas flow rate of 0-1000cc/min (e.g., 1cc/min, 5cc/min, 10cc/min, 50cc/min, 100cc/min, 300cc/min, 500cc/min, 800cc/min), a vacuum of 60-600Pa (e.g., 80Pa, 100Pa, 150Pa, 200Pa, 300Pa, 500 Pa); the membrane treatment time per time is 1-5min (e.g., 2min, 3min, 4min), and the number of intermittent treatments is 2-5 (e.g., 3, 4).
In the step, the plasma is adopted to treat the surface of the obtained fluorosilicone rubber membrane, so that the pore distribution of the membrane surface is more uniform, the porosity is increased, and the treatment capability and treatment effect in the membrane extraction process are improved.
According to the preparation method provided by the invention, in the step iv, in some examples, the surface modification liquid comprises: low surface energy substances, alcohol solvents, cross-linking agents and catalysts. In the process of immersing the obtained fluorosilicone rubber membrane with increased membrane porosity into the surface modification liquid, the surface modification liquid is used in an amount which can completely immerse the membrane immersed in the surface modification liquid.
Preferably, the low surface energy substance is selected from at least one of perfluorodecyltriethoxysilane, perfluorooctyltriethoxysilane, and 3,3, 3-trifluoropropyltrimethoxysilane;
preferably, the alcoholic solvent is isopropanol;
preferably, the cross-linking agent is ethyl orthosilicate;
preferably, the catalyst is ammonia.
More preferably, in the surface modification liquid, the ratio of low surface energy substance: isopropyl alcohol: ethyl orthosilicate: the molar ratio of ammonia water (calculated by the solute in the ammonia water) is 5 (70-90) to 2: 4; for example, the molar ratio is 5:75:2:4, 5:80:2:4, 5:85:2: 4.
In some examples, the surface modification treatment is performed for 2 to 4 hours, e.g., 2.5 hours, 3 hours, 3.5 hours.
After the surface modification treatment is completed, the treated film may be subjected to solvent evaporation at room temperature for 6-8h, and then subjected to a thermal curing treatment (e.g., transferred to an oven). In some examples, the thermal curing conditions include: the temperature is 70-100 deg.C (e.g., 80 deg.C, 90 deg.C), and the time is 8-15h (e.g., 10h, 12h, 14 h).
In another aspect, there is provided a superhydrophobic film prepared by the preparation method as described above, the superhydrophobic film having a porous structure and a rough surface.
In some preferred embodiments, the superhydrophobic film has a film thickness of 0.5 to 1.5mm (e.g., 0.6mm, 1mm, 1.2mm), and more preferably 0.6 to 0.8 mm.
In some preferred embodiments, the superhydrophobic film has a porosity of 10% to 20% (e.g., 12%, 14%, 16%, 18%).
In some preferred embodiments, the superhydrophobic film has a static water contact angle of 150 ° to 160 ° (e.g., 152 °, 155 °, 158 °).
The super-hydrophobic membrane is a super-hydrophobic fluorosilicone rubber membrane, and can be used in an extraction membrane tube of a membrane extraction device in a washing wastewater treatment process. Compared with the common separation membrane, the super-hydrophobic membrane as a porous super-hydrophobic fluorosilicone rubber membrane has the advantages of high selectivity to organic matters such as amines, high organic amine transmittance, acid resistance, organic matter swelling and the like, and is particularly suitable for the working condition of amine-containing organic wastewater in the MDI production process.
The super-hydrophobic membrane has high selectivity on organic substances such as aniline, DAM, trace cyclohexylamine and the like contained in the washing wastewater, and can effectively prevent inorganic ions and water molecules from passing through, so that the washing wastewater can be treated in a membrane extraction mode with feasibility.
In yet another aspect, a method for concentrating and recycling MDI waste brine is provided, comprising the steps of:
1) carrying out two-phase separation on MDI waste brine to generate an organic phase and a brine phase;
2) sequentially carrying out aniline extraction, reboiling distillation and brine advanced treatment to remove TOC on the brine phase obtained by separation in the step 1), wherein the treated brine is used as a raw material of a chlor-alkali device;
3) washing the organic phase obtained by separation in the step 1) to obtain a washed organic phase and washing wastewater; contacting the washing wastewater with an extracting agent to carry out membrane extraction treatment; conveying the water washing wastewater subjected to membrane extraction treatment to a biochemical unit for treatment, and then, feeding the water washing wastewater into a reclaimed water recycling system for recycling;
in the membrane extraction treatment process, the washing wastewater to be treated is subjected to membrane extraction treatment through the super-hydrophobic membrane prepared by the preparation method or the super-hydrophobic membrane.
In the present invention, the MDI waste brine to be treated may be a product obtained by mixing a reaction solution containing diamines and polyamines (DAM) of the diphenylmethane series, which is obtained by reacting aniline and formaldehyde, with a sodium hydroxide solution in the presence of, for example, a hydrochloric acid catalyst to perform a neutralization reaction. The operation of neutralization treatment of the reaction solution containing a diamine of the diphenylmethane series and a polyamine (DAM) is well known to those skilled in the art and will not be described herein.
The aqueous salt phase obtained after the two-phase separation in step 1) is an aqueous salt solution containing aniline and DAM, and generally comprises the following main components: the mass fraction of NaCl is 17-22%, the mass fraction of NaOH is 0.5-2%, and the total mass fraction of aniline and DAM is 0.2-3%.
The operation of carrying out the separation of the two phases in step 1) according to the process provided by the invention is well known to the person skilled in the art and will not be described in detail here.
According to the method provided by the invention, in the step 2), the processes of aniline extraction, reboiling distillation and brine advanced treatment for removing TOC, which are sequentially carried out on the brine phase, are well known to those skilled in the art and are not described herein again. For example, the technique of catalytic oxidation removal of TOC with sodium hypoxide as disclosed in patent document CN201610719105.1 can be used.
In some examples, the composition of the brine after the treatment in step 2) comprises: the NaCl content is 21-25 wt%, the TOC is less than or equal to 10mg/L, and the TN is less than or equal to 3 mg/L. Compared with the brine obtained by the existing treatment process, the step realizes effective concentration of MDI waste brine, and the NaCl content in the treated brine is increased by 6-8 wt%; the method can ensure that the MDI waste brine is completely recycled as the chlor-alkali raw material under the condition of keeping the matching of the chlor-alkali device capacity and the MDI device capacity.
The water washing wastewater to be treated in step 3) is washing wastewater obtained after washing the organic phase and separated from the organic phase, and generally comprises the following components: the mass percent of aniline is 1-3%, the mass percent of DAM is less than 1%, the mass percent of NaCl is less than 1000mg/L, and the mass percent of NaOH is less than 200 ppm.
The washing of the organic phase in step 3) is well known to the person skilled in the art and will not be described in further detail here.
In some examples, the membrane extraction process is performed in a membrane extraction apparatus. The membrane extraction device in the step 3) can select a conventional membrane extractor, such as a shell-and-tube membrane extractor; the membrane extraction device is characterized in that the super-hydrophobic membrane is used in an extraction membrane layer of the membrane extraction device.
In some preferred embodiments, the superhydrophobic film is located in a tube layer of a membrane extraction device, and the extractant is disposed in a shell layer of the membrane extraction device.
In the membrane extraction treatment in the step 3), the washing wastewater to be treated enters a tube layer of the membrane extraction device, and the extracting agent is positioned in a shell layer of the membrane extraction device. Aniline, diphenylmethane diamine, polyamine (DAM) and other substances contained in the washing wastewater to be treated can penetrate through the super-hydrophobic membrane in the tube layer to enter the extracting agent, and react with the extracting agent to generate aniline hydrochloride, diamine hydrochloride, polyamine hydrochloride and other substances which cannot penetrate through the super-hydrophobic membrane, so that the concentration of the aniline, diphenylmethane diamine, polyamine (DAM) and other amine substances existing in the form of amine molecules in the extracting agent is always zero, and thus, concentration difference driving force always exists on two sides of the super-hydrophobic membrane in the membrane extraction treatment process, and further, the mass transfer speed in the membrane extraction treatment process is ensured. The crude product containing aniline hydrochloride, diamine hydrochloride and polyamine hydrochloride obtained after extraction can be recycled to an MDI device and used as part of raw materials for condensation reaction of aniline and formaldehyde.
According to the method provided by the invention, in some examples, the extracting agent is a hydrochloric acid aqueous solution, and the mass concentration of the hydrochloric acid aqueous solution is 5-40%, and preferably 30-37%.
In some examples, the feed volume flow ratio of the extractant to the wash wastewater is 0.1 to 0.3 (e.g., 0.12, 0.16, 0.18, 0.22, 0.25), preferably 0.15 to 0.20.
In some examples, the feeding temperature of the extracting agent can be controlled to be 20-35 ℃.
In some examples, the temperature of the water washing wastewater at the inlet of the tube layer of the membrane extraction device is controlled to be 40-60 ℃, and preferably 45-50 ℃.
In some examples, the average residence time of the extractant and the water-wash wastewater in the membrane extraction device is 40-80min, preferably 50-60 min.
In step 3), the biochemical treatment process performed in the biochemical unit and the reclaimed water recycling process performed in the reclaimed water recycling system are well known to those skilled in the art, and are not described herein again.
In the invention, the brine phase obtained by separation in the step 1) is not mixed with any amount of washing wastewater obtained after washing the organic phase to carry out the subsequent treatment process, but the brine phase is separately treated in the step 2) and the washing wastewater obtained after washing the organic phase is separately treated in the step 3).
After membrane extraction treatment, a crude product containing aniline hydrochloride, diamine hydrochloride and polyamine hydrochloride and treated water washing wastewater can be obtained. In step 3), the composition of the water-washing wastewater after the membrane extraction treatment comprises: DAM is less than or equal to 1mg/L, aniline is less than or equal to 100mg/L, COD and less than or equal to 500 mg/L; the water washing wastewater after membrane extraction treatment can meet the requirement of entering a biochemical unit for treatment. The crude product containing aniline hydrochloride, diamine hydrochloride and polyamine hydrochloride obtained after extraction can be directly used as a catalyst for condensation reaction of aniline and formaldehyde for recycling.
The invention develops a low-cost, simple and efficient treatment method for concentrating the waste brine in the DAM production process from the process source and realizing complete resource utilization. The method does not mix the low-salt-concentration water-washing wastewater obtained after washing an organic phase by any amount with the neutralized brine, but separately carries out solvent extraction, distillation and TOC removal on the neutralized brine (namely a brine phase) to form high-concentration brine with the mass fraction of sodium chloride of 21-25%. Compared with the existing treatment process for mixing the two, the concentration of the treated brine is improved by 6-8%, and the problem that MDI waste brine cannot be completely recycled under the condition that the chlor-alkali capacity is matched with MDI is solved.
Meanwhile, the invention develops a separate treatment and recycling process of the washing wastewater. For the process, if a treatment method which is consistent with the neutralization brine is adopted, the risks of small density difference of two phases, overlarge equipment size and unstable effect during aniline extraction exist; when the extraction is replaced by another solvent such as toluene, which is disclosed in patent document CN200980118981.7, new impurities are introduced and the treatment process becomes complicated. The invention combines the 'membrane extraction treatment' process with the 'biochemistry + reclaimed water recycling' process, and the extractant is not in direct contact with the washing wastewater to be treated any more in the membrane extraction process, thereby simplifying the process flow and fundamentally avoiding the steam consumption in the washing wastewater treatment process.
Compared with the existing treatment process of mixing the neutralization brine and the washing wastewater in the MDI waste brine treatment, the integral method disclosed by the invention has the advantages that the energy consumption is lower and the separation efficiency is high while the concentration of the byproduct brine of the MDI is improved, so that the complete resource utilization of the neutralization brine and the washing wastewater in the MDI waste brine is realized.
Compared with the prior art, the technical scheme of the invention has the following beneficial effects:
the porous fluorosilicone rubber super-hydrophobic membrane has uniform pore distribution, no defects and rough surface, wherein the fluorosilicone rubber layer is prepared at one time, is firmly adhered to the low surface energy modification layer, has high selectivity and high permeability on organic amine substances, and is particularly suitable for the working condition of MDI waste brine.
According to the invention, the hydrochloric acid aqueous solution is preferably used as an extracting agent, and the organic amine substances in the water washing wastewater are extracted in the membrane extraction device (the tube layer of the membrane extraction device is provided with the super-hydrophobic membrane prepared from the fluorosilicone rubber material), so that the water washing wastewater to be treated is not directly contacted with the extracting agent (hydrochloric acid aqueous solution), and the problems of emulsification and solvent separation in the traditional solvent extraction process are avoided; the energy consumption in wastewater treatment is lower while the process is simplified, and the crude product containing aniline hydrochloride, diamine hydrochloride and polyamine hydrochloride after extraction can be further recycled as the raw material of condensation reaction of aniline and formaldehyde, so that the process is more green and environment-friendly compared with the traditional process. The method can treat the washing wastewater in the MDI production process until the COD in the composition is less than or equal to 500mg/L, DAM and less than or equal to 1mg/L and the aniline is less than or equal to 100mg/L, thereby meeting the requirements of subsequent biochemical treatment, and the wastewater can be recycled in a reclaimed water recycling system after the biochemical treatment.
According to the invention, the neutralization brine (brine phase) in the MDI waste brine and the washing waste water obtained after washing the neutralization organic phase with any amount are not mixed together for subsequent treatment, but the brine phase and the washing waste water are separately subjected to different process treatment processes, so that high-concentration brine with the sodium chloride content of 21-25% by mass can be obtained, the concentration of the MDI waste brine is realized, and the NaCl content in the treated brine is increased by 6-8 wt%; the method can ensure that the MDI waste brine is completely recycled as the chlor-alkali raw material under the condition of keeping the matching of the chlor-alkali device capacity and the MDI device capacity.
Therefore, the invention realizes the complete resource recycling of MDI waste salt and wastewater in the MDI production process on the premise of saving energy and cost.
Detailed Description
In order that the technical features and contents of the present invention can be understood in detail, preferred embodiments of the present invention will be described in more detail below. While the preferred embodiments of the present invention have been described in the examples, it should be understood that the present invention may be embodied in various forms and should not be limited by the embodiments set forth herein.
< sources of raw materials >
Epoxy resin adhesive provided by Jinshengji chemical Co., Ltd, Guangzhou city;
liquid fluorosilicone rubber (FVMQ) with viscosity of 60-90 Pa.s (25 ℃), provided by Shanghai Shudi fluorosilicone materials Co., Ltd;
triethylene tetramine (analytically pure), vinyl triamine and dipropylene triamine (analytically pure), both provided by WUD Ikoda Chemicals Co., Ltd.;
3,3, 3-trifluoropropyltrimethoxysilane, with the purity of 98 percent, is provided by Jiangtai Taihua chemical Co., Ltd, Hubei;
perfluorodecyl triethoxysilane, purity 98%, available from Toming chemical Co., Ltd., Quzhou city;
perfluorooctyl triethoxysilane, purity 98%, available from Toming chemical Co., Ltd., Quzhou city;
isopropanol, analytically pure, provided by Ningbo Chang remote instruments Inc.;
ethyl orthosilicate, analytically pure, provided by Fochen chemical reagent factory, Tianjin;
a general silicone rubber membrane material, a PDMS membrane provided by slex ltd, uk, consisting of 30 wt% of fumed silica and 70 wt% of Polydimethylsiloxane (PDMS), which is a hydrophobic dense membrane; the porosity was 4.75%, the film thickness was 1.0mm, and the static water contact angle was 101 °.
The MDI waste brine to be treated is reaction liquid obtained in the reaction of preparing DAM from aniline and formaldehyde, and a large amount of high-concentration brine and washing wastewater generated after washing a neutralized organic phase are generated after the neutralization treatment is carried out by using caustic soda.
< test methods >
A membrane extraction device: the structure of the device is similar to a shell-and-tube heat exchanger and comprises a shell, a seal head, a tube plate and an extraction membrane tube; wherein, the extraction membrane tube is made of the fluorosilicone rubber super-hydrophobic membrane prepared by the invention, the end sockets at two ends are provided with feeding and discharging pipe orifices for washing wastewater, and the end sockets at two ends are connected with the tube plates fixed at two ends of the shell by flanges; a feed inlet and a discharge outlet of an extracting agent (hydrochloric acid aqueous solution) are arranged on the shell, a plurality of baffling support plates are arranged in the shell, and the inner diameter of the shell is 2.5 m; the length of the extraction membrane tubes is 6m, the inner diameter of the extraction membrane tubes is 15mm, the thickness of the extraction membrane tubes is 0.5-1.5mm, the number of the membrane tubes is 450, and the spacing between the support baffles is 500 mm.
Method for testing performance parameters of membranes obtained in various examples
(1) Determination of the porosity of the membrane: the measurements were performed using an American Mike fully automatic AutoPore mercury porosimeter with pressure settings at 40 psi.
(2) Film thickness was analyzed by SEM: the obtained fluorosilicone rubber superhydrophobic film was frozen in liquid nitrogen, and a sample was rapidly cut in the longitudinal direction with a blade, and the thickness of the film sample was analyzed by Scanning Electron Microscope (SEM) of model S-4800 of hitachi, japan.
(3) Static water contact angle: and (3) adopting a contact angle tester JC2000D1 model of Shanghai Zhongchen digital technology equipment Limited to determine a fixed image when 0.2 mu L of water drops are dropped on the active surface of the prepared fluorosilicone rubber super-hydrophobic film for 10s under the conditions of room temperature and 60% humidity.
Method for measuring contents of components in brine phase and water-washing wastewater in each example and comparative example
The determination of the salt content (e.g., sodium hydroxide, sodium chloride, etc.) is obtained using a potentiometric titration method;
the content measurement of aniline and DAM is obtained by Liquid Chromatography (LC);
the COD content is measured by a potassium dichromate oxidation method;
the TOC and TN contents were determined by a German Yena TOC analyzer using the combustion method.
Example 1
1. The super-hydrophobic membrane used by the membrane extraction device is prepared according to the following steps:
i. preparing a bionic template: a) uniformly coating an epoxy resin adhesive on a glass substrate, and then uniformly paving micron-sized silicon carbide particles on the epoxy resin adhesive on the glass substrate, wherein the particle size of the silicon carbide particles is 5 mu m; b) placing the glass substrate fully paved with the micron-sized silicon carbide particles in an oven, curing at 100 ℃ for 80min, raising the temperature to 160 ℃, baking for 15min, taking out and cooling to below 100 ℃; c) uniformly blowing the surface of the epoxy resin adhesive for 15min by using a blower, and removing silicon carbide particles which are not fixed on the surface of the epoxy resin adhesive to form a bionic template similar to a lotus leaf effect;
ii. Preparing a fluorosilicone rubber film with a rough surface: mixing liquid fluorosilicone rubber (FVMQ): curing agent: mixing the solvents according to the mass ratio of 100:8:20, stirring for 0.5h at the rotating speed of 300r/min to prepare a casting solution, wherein the curing agent is triethylene tetramine, and the solvent is acetone, and then uniformly coating the casting solution on the surface of the prepared bionic template with the silicon carbide particles fixed thereon; naturally volatilizing the solvent at room temperature for 15h, curing to form a film, then moving to an oven and drying at 80 ℃ for 6h, and then stripping the film on the glass substrate to obtain the FVMQ film with a rough surface;
iii, plasma surface treatment: fixing the obtained FVMQ film on a support plate of a plasma surface treatment instrument, opening a switch of the treatment instrument, introducing ammonia gas, and setting parameter conditions as follows: the radio frequency power is 120W, the gas flow is 600cc/min, the vacuum degree is 300Pa, the single treatment time of the basal membrane is 3min, the intermittent treatment is carried out for 3 times, and then the basal membrane is sealed and stored, thus obtaining the fluorine silicon rubber membrane with increased membrane porosity; the porosity of the film is increased from 6.23% to 19.58%;
iv, 3, 3-trifluoropropyltrimethoxysilane: isopropyl alcohol: ethyl orthosilicate: preparing a surface modification solution with the molar ratio of ammonia water to ammonia water of 5:80:2: 4; completely immersing the fluorosilicone rubber membrane with the increased membrane porosity in the surface modification solution in the step iii, and carrying out surface modification treatment for 3 h; naturally volatilizing the solvent at room temperature for 8h after reaction, and then transferring the solvent to an oven for heat curing treatment at 90 ℃ for 15h to obtain a porous fluorosilicone rubber super-hydrophobic membrane I; the static water contact angle was 159 ℃ and the film thickness was 0.8 mm.
2. The prepared fluorosilicone rubber super-hydrophobic membrane I is placed in a tube layer of a membrane extraction device and is used for a method for concentrating and recycling MDI waste brine.
3. The method for concentrating and recycling MDI waste brine comprises the following steps:
1) introducing MDI waste brine to be treated into a delayer at the temperature of 100-108 ℃, staying for 20min for two-phase separation, and separating to obtain an organic phase and a brine phase; the composition of the neutralized brine (i.e., the resulting brine phase) includes: NaCl 18.5 wt%, NaOH 0.9 wt%, aniline and DAM 0.9 wt%, and waste water 80m3/h；
2) Separately and sequentially carrying out aniline extraction, reboiling distillation and brine advanced treatment to remove TOC (in the aniline extraction treatment process, the feeding mass ratio of aniline to brine is 0.22:1, the aniline feeding temperature is 30 ℃ and the brine feeding temperature is 100 ℃; the process of reboiling distillation is carried out by using a thermosiphon reboiling distillation tower without reflux, a reboiler is heated by 2kg of steam, the addition amount of the steam and the feeding quality of the neutralized salt waterThe ratio is 0.14, and the feeding temperature of the salt neutralizing water is 95 ℃; in the treatment process of advanced treatment and TOC removal of brine, the temperature of neutralized brine is cooled to 50 ℃, the feed is fed, the pH is adjusted to 12, the neutralized brine is mixed with a sodium hypochlorite aqueous solution with the concentration of 5 percent below 30 ℃ in a mass ratio of 100:1, the mixture enters a fixed bed tower reactor, the filling amount of a catalyst in the tower reactor enables the space velocity of the feed to be 5), and the flow of the treated brine is 65m3H; compared with the treatment process of mixing the brine phase with the washing wastewater, the NaCl content in the brine obtained after treatment is increased by 6.7 wt%; the composition of the treated brine comprised: the NaCl content is 22.5 wt%, the TOC content is 6.7mg/L, the TN content is 1.2mg/L, and the NaCl content can be completely used as a raw material of a chlor-alkali device;
3) mixing the organic phase separated in the step 1) with aniline water generated in a process of reboiling and distilling by using a DAM refining unit and neutralized brine (wherein, the aniline water of the DAM refining unit is obtained from the following processes: heating a mixed material containing 9% of water, 21% of aniline and 70% of DAM to 105 ℃ at 95 ℃, carrying out flash evaporation at 12Kpa absolute pressure, heating a liquid phase to 200 ℃ after the flash evaporation, introducing into a stripping tower, introducing 8kg of steam into the mixed material at 9Kpa absolute pressure and 95 ℃ at the tower bottom according to the mass ratio of feeding to 0.08:1 for stripping, cooling an aniline water-gas phase generated at the top of the flash evaporation and stripping tower to 20 ℃, standing in a delayer for 25min, separating an aniline phase and a water phase 1, wherein the water phase 1 is the aniline water generated by a DAM refining unit; the reboiling distillation process of the neutralized brine comprises the following steps: cooling aniline water generated at the top of the tower to 20 ℃, standing in a delayer for 25min, separating an aniline phase and a water phase 2, wherein the water phase 2 is aniline water generated by reboiling and distilling neutralized brine; combining the water phase 1 and the water phase 2 to obtain aniline water for washing the organic phase obtained by separation in the step 1)), mixing in a stirring tank at 90-98 ℃ for washing treatment, then entering a delayer, and staying for 25min to obtain the washed organic phase and washing wastewater; the washing wastewater comprises the following components: aniline mass fraction of 2.5%, DAM mass fraction of 0.7%, NaCl content of 500mg/L, NaOH content of 100ppm, and wastewater amount of 35m3/h；
Respectively conveying the washing wastewater to be treated and hydrochloric acid aqueous solution serving as an extracting agent into a membrane tube layer and a shell layer of a membrane extraction device for membrane extraction treatment; wherein the mass concentration of the hydrochloric acid aqueous solution is 30%, the volume flow ratio of the hydrochloric acid aqueous solution to the washing wastewater is 0.2, the hydrochloric acid temperature at the inlet of the shell layer is 30 ℃, the washing wastewater temperature at the inlet of the membrane tube is 45 ℃, and the average residence time of extraction is 50 min. The water washing wastewater after the membrane extraction treatment comprises the following components: the COD content is 321mg/L, DAM content is 0.5mg/L, the aniline content is 63mg/L, the mixture is conveyed to a biochemical unit for further treatment, and then the mixture is conveyed to a reclaimed water recycling unit for recycling. The crude product containing aniline hydrochloride, diamine hydrochloride and polyamine hydrochloride obtained after extraction can be recycled to an MDI device and used as part of raw materials for condensation reaction of aniline and formaldehyde.
Example 2
1. The super-hydrophobic membrane used by the membrane extraction device is prepared according to the following steps:
i. preparing a bionic template: a) uniformly coating an epoxy resin adhesive on a glass substrate, and then uniformly paving micron-sized silicon carbide particles on the epoxy resin adhesive on the glass substrate, wherein the particle size of the silicon carbide particles is 3 mu m; b) placing the glass substrate fully paved with the micron-sized silicon carbide particles in an oven, curing at 100 ℃ for 60min, raising the temperature to 160 ℃, baking for 15min, taking out and cooling to below 100 ℃; c) uniformly blowing the surface of the epoxy resin adhesive for 15min by using a blower, and removing silicon carbide particles which are not fixed on the surface of the epoxy resin adhesive to form a bionic template similar to a lotus leaf effect;
ii. Preparing a fluorosilicone rubber film with a rough surface: mixing liquid fluorosilicone rubber (FVMQ): curing agent: mixing the solvents according to the mass ratio of 100:5:20, stirring for 0.5h at the rotating speed of 300r/min to prepare a casting solution, wherein the curing agent is vinyl triamine, and the solvent is acetone, and then uniformly coating the casting solution on the surface of the prepared bionic template with the fixed silicon carbide particles; naturally volatilizing the solvent at room temperature for 18h, curing to form a film, then moving to an oven and drying at 80 ℃ for 6h, and then stripping the film on the glass substrate to obtain the FVMQ film with a rough surface;
iii, plasma surface treatment: fixing the FVMQ film on a support plate of a plasma surface treatment instrument, turning on a switch of the treatment instrument, introducing ammonia gas and nitrogen gas into the plasma surface treatment instrument according to the volume ratio of 1:1, and setting parameter conditions as follows: the radio frequency power is 100W, the gas flow is 500cc/min, the vacuum degree is 400Pa, the single treatment time of the basal membrane is 2min, the intermittent treatment is carried out for 4 times, and then the basal membrane is sealed and stored, so that the fluorosilicone rubber membrane with the increased membrane porosity is obtained, and the membrane porosity is increased from 6.47% to 16.58%;
iv, as per perfluorodecyltriethoxysilane: isopropyl alcohol: ethyl orthosilicate: preparing a surface modification solution with the molar ratio of ammonia water to ammonia water of 5:75:2: 4; completely immersing the fluorosilicone rubber membrane with the increased membrane porosity in the surface modification solution in the step iii, and carrying out surface modification treatment for 4 hours; naturally volatilizing the solvent at room temperature for 8h after reaction, and then transferring to an oven for heat curing treatment at 90 ℃ for 15h to obtain a porous fluorosilicone rubber super-hydrophobic membrane II; the static water contact angle was 155 ℃ and the film thickness was 0.6 mm.
2. The prepared fluorosilicone rubber super-hydrophobic membrane II is placed in a tube layer of a membrane extraction device and is used for a method for concentrating and recycling MDI waste brine. The dimensions of the membrane extraction device were the same as in example 1.
3. The method for concentrating and recycling MDI waste brine comprises the following steps:
1) introducing MDI waste brine to be treated into a delayer at the temperature of 100-108 ℃, staying for 20min for two-phase separation, and separating to obtain an organic phase and a brine phase; the composition of the neutralized brine (i.e., the resulting brine phase) includes: NaCl 20.5 wt%, NaOH 1.2 wt%, aniline and DAM 1.5 wt%, and waste water 80m3/h；
2) The neutralized brine is separately and sequentially treated by aniline extraction (see example 1 for specific treatment process), reboiling distillation (see example 1 for specific treatment process) and brine deep treatment for removing TOC (see example 1 for specific treatment process), and the treated brine flow is 65m3H; compared with the treatment process of mixing the brine phase and the washing wastewater, the NaCl content in the treated brine is improved by 7.6 wt%; the composition of the treated brine comprised: the NaCl content is 24 wt%, the TOC content is 5.5mg/L, the TN content is 0.8mg/L, and the NaCl content can be completely used as a raw material of a chlor-alkali device;
3) mixing the organic phase obtained by separation in the step 1) with aniline water generated in a DAM refining unit and a neutralization brine reboiling distillation process (the preparation process of the aniline water is shown in an example 1) in a stirring tank at 90-98 ℃ for washing treatment, then entering a delayer, and staying for 25min to obtain a washed organic phase and washing wastewater; the washing wastewater comprises the following components: aniline mass fraction of 2.2%, DAM mass fraction of 0.4%, NaCl content of 300mg/L, NaOH content of 60ppm, and wastewater amount of 35m3/h；
Respectively conveying the washing wastewater to be treated and hydrochloric acid aqueous solution serving as an extracting agent into a membrane tube layer and a shell layer of a membrane extraction device for membrane extraction treatment; wherein the mass concentration of the hydrochloric acid aqueous solution is 34%, the volume flow ratio of the hydrochloric acid aqueous solution to the washing wastewater is 0.15, the hydrochloric acid temperature at the inlet of the shell layer is 35 ℃, the washing wastewater temperature at the inlet of the membrane tube is 55 ℃, and the average residence time of extraction is 60 min. The water washing wastewater after the membrane extraction treatment comprises the following components: the COD content is 270mg/L, DAM content is 0.3mg/L, the aniline content is 42mg/L, the mixture is conveyed to a biochemical unit for further treatment, and then the mixture is conveyed to a reclaimed water recycling unit for recycling. The crude product containing aniline hydrochloride, diamine hydrochloride and polyamine hydrochloride obtained after extraction can be recycled to an MDI device and used as part of raw materials for condensation reaction of aniline and formaldehyde.
Example 3
1. The superhydrophobic membrane used in the membrane extraction device was prepared according to the method described in example 1, except that:
i. preparing a bionic template: the grain diameter of the silicon carbide particles is 8 mu m, and the curing treatment time at 100 ℃ is 70 min;
ii. Preparing a fluorosilicone rubber film with a rough surface: mixing liquid fluorosilicone rubber (FVMQ): curing agent: mixing the solvents according to the mass ratio of 100:7:30, wherein the curing agent is dipropylene triamine, and the solvent is ethanol;
iii, plasma surface treatment: introducing ammonia gas and air in the plasma surface treatment instrument according to the volume ratio of 1:1, and setting parameter conditions as follows: the radio frequency power is 80W, the gas flow is 700cc/min, the vacuum degree is 200Pa, the single treatment time of the basement membrane is 4min, and the intermittent treatment is carried out for 2 times; finally obtaining the fluorine silicon rubber membrane with increased membrane porosity, wherein the membrane porosity is increased from 6.47% to 11.59%;
4) as per perfluorooctyltriethoxysilane: isopropyl alcohol: ethyl orthosilicate: preparing a surface modification solution with the molar ratio of ammonia water to ammonia water of 5:90:2: 4; completely immersing the fluorosilicone rubber membrane with the increased membrane porosity in the step III into surface modification liquid, and carrying out surface modification treatment for 2h to obtain a porous fluorosilicone rubber super-hydrophobic membrane III; the static water contact angle was 153 ℃ and the film thickness was 1.2 mm.
2. The prepared fluorosilicone rubber super-hydrophobic membrane III is placed in a tube layer of a membrane extraction device and is used for a method for concentrating and recycling MDI waste brine. The dimensions of the membrane extraction device were the same as in example 1.
3. The method for concentrating and recycling MDI waste brine comprises the following steps:
1) introducing MDI waste brine to be treated into a delayer at the temperature of 100-108 ℃, staying for 20min for two-phase separation, and separating to obtain an organic phase and a brine phase; the composition of the neutralized brine (i.e., the resulting brine phase) includes: the mass fraction of NaCl is 19%, the mass fraction of NaOH is 0.6%, the total mass fraction of aniline and DAM is 1.8%, and the wastewater amount is 80m3/h；
2) The neutralized brine is separately and sequentially treated by aniline extraction (see example 1 for specific treatment process), reboiling distillation (see example 1 for specific treatment process) and brine deep treatment for removing TOC (see example 1 for specific treatment process), and the treated brine flow is 65m3H; compared with the treatment process of mixing the brine phase with the washing wastewater, the NaCl content in the brine obtained after treatment is increased by 6.9 wt%; the composition of the treated brine comprised: the NaCl content is 23 wt%, the TOC content is 6.1mg/L, the TN content is 0.9mg/L, and the NaCl content can be completely used as a raw material of a chlor-alkali device;
3) mixing the organic phase separated in step 1) with aniline water produced in DAM refining unit and neutralization brine reboiling distillation process (see example 1 for preparation process of aniline water), washing in a stirring tank at 90-98 deg.C, and standing in a delayer25min to obtain a washed organic phase and washing wastewater; the washing wastewater comprises the following components: aniline mass fraction of 2.8%, DAM mass fraction of 0.6%, NaCl content of 700mg/L, NaOH content of 80ppm, and wastewater amount of 35m3/h；
Respectively conveying the washing wastewater to be treated and hydrochloric acid aqueous solution serving as an extracting agent into a membrane tube layer and a shell layer of a membrane extraction device for membrane extraction treatment; wherein the mass concentration of the hydrochloric acid aqueous solution is 25%, the volume flow ratio of the hydrochloric acid aqueous solution to the washing wastewater is 0.2, the hydrochloric acid temperature at the inlet of the shell layer is 30 ℃, the washing wastewater temperature at the inlet of the membrane tube is 45 ℃, and the average residence time of extraction is 40 min. The water washing wastewater after the membrane extraction treatment comprises the following components: the COD content is 453mg/L, DAM content and 96mg/L aniline content, the materials are conveyed to a biochemical unit for further treatment, and then conveyed to a reclaimed water recycling unit for recycling. The crude product containing aniline hydrochloride, diamine hydrochloride and polyamine hydrochloride obtained after extraction can be recycled to an MDI device and used as part of raw materials for condensation reaction of aniline and formaldehyde.
Example 4
1. The superhydrophobic membrane used in the membrane extraction device was prepared according to the method described in example 2, except that:
i. preparing a bionic template: the grain diameter of the silicon carbide particles is 12 mu m, and the curing treatment time at 100 ℃ is 50 min;
ii. Preparing a fluorosilicone rubber film with a rough surface: mixing liquid fluorosilicone rubber (FVMQ): curing agent: mixing the solvents according to the mass ratio of 100:6:25, wherein the curing agent is vinyl triamine, and the solvent is ethanol;
iii, plasma surface treatment: in the plasma surface treatment instrument, the parameter conditions are set as follows: the radio frequency power is 50W, the gas flow is 200cc/min, the vacuum degree is 500Pa, the single treatment time of the basement membrane is 5min, and the intermittent treatment is carried out for 2 times; finally obtaining the fluorine silicon rubber membrane with increased membrane porosity, wherein the membrane porosity is increased from 6.47% to 10.59%;
iv, as per perfluorodecyltriethoxysilane: isopropyl alcohol: ethyl orthosilicate: preparing a surface modification solution with the molar ratio of ammonia water to ammonia water of 5:70:2: 4; completely immersing the fluorosilicone rubber membrane with the increased membrane porosity in the surface modification solution in the step iii; after the reaction, naturally volatilizing the solvent at room temperature, transferring the solvent to an oven, and performing thermal curing treatment at 100 ℃ for 10 hours to obtain a porous fluorosilicone rubber super-hydrophobic membrane IV; the static water contact angle was 150 ℃ and the film thickness was 1.0 mm.
2. The prepared fluorosilicone rubber super-hydrophobic membrane IV is placed in a tube layer of a membrane extraction device and is used for a method for concentrating and recycling MDI waste brine. The dimensions of the membrane extraction device were the same as in example 1.
3. The method for concentrating and recycling MDI waste brine comprises the following steps:
1) introducing MDI waste brine to be treated into a delayer at the temperature of 100-108 ℃, staying for 20min for two-phase separation, and separating to obtain an organic phase and a brine phase; the composition of the neutralized brine (i.e., the resulting brine phase) includes: the mass fraction of NaCl is 17.5%, the mass fraction of NaOH is 1.8%, the total mass fraction of aniline and DAM is 1.8%, and the wastewater amount is 80m3/h；
2) The neutralized brine is separately and sequentially treated by aniline extraction (see example 1 for specific treatment process), reboiling distillation (see example 1 for specific treatment process) and brine deep treatment for removing TOC (see example 1 for specific treatment process), and the treated brine flow is 65m3H; compared with the treatment process of mixing the brine phase with the washing wastewater, the NaCl content in the brine obtained after treatment is improved by 7.3 wt%; the composition of the treated brine comprised: the NaCl content is 23 wt%, the TOC content is 6.1mg/L, the TN content is 0.9mg/L, and the NaCl content can be completely used as a raw material of a chlor-alkali device;
3) mixing the organic phase obtained by separation in the step 1) with aniline water generated in a DAM refining unit and a neutralization brine reboiling distillation process (the preparation process of the aniline water is shown in an example 1) in a stirring tank at 90-98 ℃ for washing treatment, then entering a delayer, and staying for 25min to obtain a washed organic phase and washing wastewater; the washing wastewater comprises the following components: aniline mass fraction of 1.9%, DAM mass fraction of 0.3%, NaCl content of 300mg/L, NaOH content of 40ppm, and wastewater amount of 35m3/h；
Respectively conveying the washing wastewater to be treated and hydrochloric acid aqueous solution serving as an extracting agent into a membrane tube layer and a shell layer of a membrane extraction device for membrane extraction treatment; wherein the mass concentration of the hydrochloric acid aqueous solution is 25%, the volume flow ratio of the hydrochloric acid aqueous solution to the washing wastewater is 0.2, the hydrochloric acid temperature at the inlet of the shell layer is 30 ℃, the washing wastewater temperature at the inlet of the membrane tube is 45 ℃, and the average residence time of extraction is 40 min. The water washing wastewater after the membrane extraction treatment comprises the following components: the COD content is 380mg/L, DAM content is 0.7mg/L, the aniline content is 82mg/L, the mixture is conveyed to a biochemical unit for further treatment, and then the mixture is conveyed to a reclaimed water recycling unit for recycling. The crude product containing aniline hydrochloride, diamine hydrochloride and polyamine hydrochloride obtained after extraction can be recycled to an MDI device and used as part of raw materials for condensation reaction of aniline and formaldehyde.
Comparative example 1
1. In the method for concentrating and recycling MDI waste brine, the structural size of a membrane extraction device is the same as that of the embodiment 1, except that: the membrane tube layer of the membrane extraction device uses a common silicone rubber membrane material (PDMS membrane supplied by slex ltd, uk).
2. The method for concentrating and recycling MDI waste brine comprises the following steps:
1) introducing MDI waste brine to be treated into a delayer at the temperature of 100-108 ℃, staying for 20min for two-phase separation, and separating to obtain an organic phase and a brine phase; the composition of the neutralized brine (i.e., the resulting brine phase) includes: NaCl 20 wt%, NaOH 1 wt%, aniline and DAM 1.2 wt%, and waste water 80m3/h；
2) Mixing the organic phase obtained by separation in the step 1) with aniline water generated in a DAM refining unit and a neutralization brine reboiling distillation process (the preparation process of the aniline water is shown in an example 1) in a stirring tank at 90-98 ℃ for washing treatment, then entering a delayer, and staying for 25min to obtain a washed organic phase and washing wastewater; the washing wastewater comprises the following components: aniline mass fraction of 2.0%, DAM mass fraction of 0.5%, NaCl content of 400mg/L, NaOH content of 100ppm, and wastewater amount of 35m3/h；
3) The total amount of neutralized brine (i.e. brine phase) obtained in step 1) and the amount of waste water obtained in step 2) were 20m3Mixing the water washing wastewater, and then sequentially adopting aniline extraction (the specific treatment process is shown in example 1), reboiling distillation (the specific treatment process is shown in example 1) and brine advanced treatment to remove TOC (the specific treatment process is shown in example 1), wherein the amount of the brine after treatment is 80m3H; the NaCl content in the treated brine was 18.2 wt%, the TOC content was 7.1mg/L, the TN content was 0.9mg/L, and the amount of brine was about 10m3The reaction time is not recycled;
4) only the amount of wastewater was 15m3Respectively conveying the water washing wastewater and hydrochloric acid aqueous solution serving as an extracting agent into a membrane tube layer and a shell layer of a membrane extraction device for membrane extraction treatment; wherein the mass concentration of the hydrochloric acid aqueous solution is 30%, the volume flow ratio of the hydrochloric acid aqueous solution to the washing wastewater is 0.2, the hydrochloric acid temperature at the inlet of the shell layer is 30 ℃, the washing wastewater temperature at the inlet of the membrane tube is 45 ℃, and the average residence time of extraction is 50 min. The water washing wastewater after the membrane extraction treatment comprises the following components: the COD content is 3240mg/L, DAM content is 63mg/L, the aniline content is 750mg/L, which is far beyond the receiving index of the wastewater of a biochemical system, and the wastewater cannot be further biochemically treated.
Comparative example 2
1. The superhydrophobic membrane used in the membrane extraction device was prepared according to the method described in example 1, except that: and (5) not carrying out the plasma surface treatment in the step iii to obtain the fluorosilicone rubber film V. The fluorosilicone rubber film V has a film thickness of 0.8mm, a porosity of 5.8% and a static water contact angle of 151 °.
2. The prepared super-hydrophobic fluorosilicone rubber membrane V is placed in a tube layer of a membrane extraction device and is applied to a method for concentrating and recycling MDI waste brine. The dimensions of the membrane extraction device were the same as in example 1.
3. The method for concentrating and recycling MDI waste brine comprises the following steps:
1) introducing MDI waste brine to be treated into a delayer at the temperature of 100-108 ℃, staying for 20min for two-phase separation, and separating to obtain an organic phase and a brine phase; the neutralized brine (i.e., the resultantBrine phase) composition includes: NaCl 20 wt%, NaOH 1 wt%, aniline and DAM 1.2 wt%, and waste water 80m3/h；
2) Mixing the organic phase obtained by separation in the step 1) with aniline water generated in a DAM refining unit and a neutralization brine reboiling distillation process (the preparation process of the aniline water is shown in an example 1) in a stirring tank at 90-98 ℃ for washing treatment, then entering a delayer, and staying for 25min to obtain a washed organic phase and washing wastewater; the washing wastewater comprises the following components: aniline mass fraction of 2.0%, DAM mass fraction of 0.5%, NaCl content of 400mg/L, NaOH content of 100ppm, and wastewater amount of 35m3/h；
3) The total amount of neutralized brine (i.e. brine phase) obtained in step 1) and the amount of waste water obtained in step 2) were 30m3Mixing the water washing wastewater, and then sequentially adopting aniline extraction (the specific treatment process is shown in example 1), reboiling distillation (the specific treatment process is shown in example 1) and brine advanced treatment to remove TOC (the specific treatment process is shown in example 1), wherein the amount of the brine after treatment is 88m3H; the NaCl content in the treated brine was 16.8 wt%, the TOC content was 6.4mg/L, the TN content was 1.1mg/L, and the amount of brine was about 18m3The reaction time is not recycled;
4) the amount of wastewater was only 5m3Respectively conveying the water washing wastewater and hydrochloric acid aqueous solution serving as an extracting agent into a membrane tube layer and a shell layer of a membrane extraction device for membrane extraction treatment; wherein the mass concentration of the hydrochloric acid aqueous solution is 34%, the volume flow ratio of the hydrochloric acid aqueous solution to the washing wastewater is 0.2, the hydrochloric acid temperature at the inlet of the shell layer is 30 ℃, the washing wastewater temperature at the inlet of the membrane tube is 45 ℃, and the average residence time of the membrane extraction is 60 min. The water washing wastewater after the membrane extraction treatment comprises the following components: the COD content is 1850mg/L, DAM content is 27mg/L, the aniline content is 320mg/L, which exceeds the receiving index of the wastewater of the biochemical system, and the wastewater cannot be further biochemically treated.
By comparing the results obtained in each example with those obtained in the comparative example, it can be seen that:
1. separately carrying out different process treatment processes on the brine phase and the washing wastewater to obtain high-concentration brine with sodium chloride content of 21-25% by mass, so that the concentration of MDI waste brine is realized, and the NaCl content in the treated brine is increased by 6-8 wt%; under the condition of keeping the matching of the chlor-alkali device capacity and the MDI device capacity, the MDI waste brine can be completely recycled as chlor-alkali raw materials; in contrast, comparative examples 1 to 2, in which the neutralized brine (brine phase) in the MDI waste brine was mixed with an arbitrary amount of the washing waste water obtained after washing the neutralized organic phase for subsequent treatment, the effect of concentrating the MDI waste brine was not good, and the MDI waste brine could not be completely recycled as a chlor-alkali raw material.
2. The fluorosilicone rubber super-hydrophobic membrane prepared by the invention is prepared by adopting the fluorosilicone rubber layer once, is firmly adhered with the low surface energy modification layer, has higher extraction permeability and higher selectivity on organic amine substances in MDI waste brine, can meet the downstream biochemical wastewater receiving index by simply carrying out single extraction treatment on the washing wastewater, has low contents of COD, DAM and aniline in the washing wastewater obtained after treatment, and is particularly suitable for the hydrochloric acid extraction working condition of the MDI washing wastewater; meanwhile, the crude product after extraction, which contains aniline hydrochloride, diamine hydrochloride and polyamine hydrochloride, can be further recycled as a condensation reaction raw material, and is more green and environment-friendly compared with the traditional process.
In addition, the treatment process is simple, efficient and stable, and energy consumption is saved.
The utilization of the fluorosilicone rubber super-hydrophobic membrane obtained by the invention facilitates the independent treatment and recycling of MDI neutralized brine and washing wastewater, and the treatment capacity of the neutralized brine (for example, 80m of neutralized brine) in each of the above examples and comparative examples3H, 35m of washing wastewater3The respective steam consumption and resource recycling conditions are shown in Table 1:
TABLE 1 treatment methods of examples and comparative examples for steam consumption and resource reuse
Steam consumption, t/h Amount of salt water discharged and lost m3/h
Example 1 12 0
Example 2 12 0
Example 3 12 0
Example 4 12 0
Comparative example 1 19 10
Comparative example 2 22 18
Having described embodiments of the present invention, the foregoing description is intended to be exemplary, not exhaustive, and not limited to the embodiments disclosed. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the described embodiments.

Claims (10)

1. A preparation method of a super-hydrophobic membrane for extracting high-concentration organic amine wastewater is characterized by comprising the following steps:
i. preparing a bionic template: uniformly coating an epoxy resin adhesive on a glass substrate, and uniformly paving micron-sized silicon carbide particles on the epoxy resin adhesive on the glass substrate; curing and baking the mixture, cooling and removing the silicon carbide particles which are not fixed on the surface of the epoxy resin adhesive to form a bionic template similar to a lotus leaf effect;
ii. Preparing a fluorosilicone rubber film with a rough surface: uniformly mixing liquid fluorosilicone rubber, a curing agent and a solvent to prepare a casting solution, and then uniformly coating the obtained casting solution on the surface of the bionic template; curing the fluorine-containing silicone rubber into a film at room temperature, and then heating, drying and stripping to obtain a fluorine-silicon rubber film with a rough surface;
iii, plasma surface treatment: carrying out plasma surface treatment on the fluorosilicone rubber membrane to obtain the fluorosilicone rubber membrane with increased membrane porosity;
iv, immersing the obtained fluorine silicon rubber membrane with increased membrane porosity into surface modification liquid for surface modification treatment; and then carrying out thermosetting treatment to obtain the super-hydrophobic film.
2. The method according to claim 1, wherein, in step i,
the grain diameter of the micron silicon carbide particles is 0.5-15 μm, preferably 2-8 μm;
the epoxy resin adhesive is medium-temperature curing adhesive, and comprises: epoxy resin and curing agent a;
preferably, the epoxy resin is selected from one or more of bisphenol a type epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin and bisphenol P type epoxy resin; the curing agent a is selected from one or more of dicyandiamide, diethylimidazole and methyl tetracyanophthalic anhydride;
preferably, the conditions of the curing treatment include: the curing temperature is 90-110 ℃, and the curing time is 50-80 min; the baking conditions comprise: the baking temperature is 150-170 ℃, and the baking time is 8-15 min.
3. The production method according to claim 1 or 2, wherein, in step ii,
the curing agent is selected from at least one of vinyl triamine, dipropylene triamine and triethylene tetramine; and/or
The solvent is acetone and/or ethanol;
preferably, the liquid fluorosilicone rubber: curing agent: the mass ratio of the solvent is 100 (5-8) to 15-30;
preferably, the time for curing to form a film at room temperature is 10-18 h;
preferably, the conditions for heat drying include: the temperature is 70-95 ℃ and the time is 4-6 h.
4. The production method according to any one of claims 1 to 3, wherein in step iii, the conditions of the plasma surface treatment include: the radio frequency power is 10-150W, the gas flow is 0-1000cc/min, and the vacuum degree is 60-600 Pa; the membrane treatment time is 1-5min each time, and the intermittent treatment times are 2-5 times.
5. The process according to any one of claims 1 to 4, wherein, in step iv,
the surface modification liquid comprises: low surface energy substances, alcohol solvents, cross-linking agents and catalysts;
preferably, the low surface energy substance is selected from at least one of perfluorodecyltriethoxysilane, perfluorooctyltriethoxysilane, and 3,3, 3-trifluoropropyltrimethoxysilane; the alcohol solvent is isopropanol; the cross-linking agent is ethyl orthosilicate; the catalyst is ammonia water;
more preferably, in the surface modification liquid, the ratio of low surface energy substance: isopropyl alcohol: ethyl orthosilicate: the mol ratio of the ammonia water is 5 (70-90) to 2: 4;
preferably, the time of the surface modification treatment is 2-4 h;
preferably, the heat curing conditions include: the temperature is 70-100 ℃ and the time is 8-15 h.
6. A superhydrophobic film prepared by the preparation method according to any one of claims 1 to 5, wherein the superhydrophobic film has a porous structure and a rough surface;
preferably, the film thickness of the super-hydrophobic film is 0.5-1.5mm, and more preferably 0.6-0.8 mm;
preferably, the porosity of the super-hydrophobic membrane is 10% -20%;
preferably, the static water contact angle of the super-hydrophobic membrane is 150-160 °.
7. A method for concentrating and recycling MDI waste brine is characterized by comprising the following steps:
1) carrying out two-phase separation on MDI waste brine to generate an organic phase and a brine phase;
2) sequentially carrying out aniline extraction, reboiling distillation and brine advanced treatment to remove TOC on the brine phase obtained by separation in the step 1), wherein the treated brine is used as a raw material of a chlor-alkali device;
3) washing the organic phase obtained by separation in the step 1) to obtain a washed organic phase and washing wastewater; contacting the washing wastewater with an extracting agent to carry out membrane extraction treatment; conveying the water washing wastewater subjected to membrane extraction treatment to a biochemical unit for treatment, and then, feeding the water washing wastewater into a reclaimed water recycling system for recycling;
in the membrane extraction treatment process, the washing wastewater to be treated is subjected to membrane extraction treatment by the super-hydrophobic membrane prepared by the preparation method according to any one of claims 1 to 5 or the super-hydrophobic membrane according to claim 6.
8. The method of claim 7, wherein the membrane extraction treatment is performed in a membrane extraction unit;
preferably, the super-hydrophobic membrane is positioned in a tube layer of the membrane extraction device, and the extractant is placed in a shell layer of the membrane extraction device.
9. The method according to claim 7 or 8, wherein in step 3), the extracting agent is an aqueous hydrochloric acid solution with a mass concentration of 5-40%, preferably 30-37%.
10. The method according to claim 7 or 8, wherein the composition of the brine after the treatment of step 2) comprises: the NaCl content is 21-25 wt%, the TOC is less than or equal to 10mg/L, and the TN is less than or equal to 3 mg/L;
in step 3), the composition of the water-washing wastewater after the membrane extraction treatment comprises: DAM is less than or equal to 1mg/L, aniline is less than or equal to 100mg/L, and COD is less than or equal to 500 mg/L.
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