阅读说明：本技术 一种（甲基）丙烯酸废水的处理方法 (Treatment method of (methyl) acrylic acid wastewater ) 是由 王跃川 徐燕 于 2019-11-11 设计创作，主要内容包括：本发明公开了一种(甲基)丙烯酸废水的处理方法,将乙烯基单体和引发剂加入(甲基)丙烯酸废水,用光照使其转化为凝胶形式的聚合物,再经脱水和干燥得到高吸水性材料。本发明的丙烯酸废水的处理方法,其低能耗、高效率,工艺简单,并可使(甲基)丙烯酸酯生产的废水资源化利用。(The invention discloses a method for treating (methyl) acrylic acid wastewater, which comprises the steps of adding a vinyl monomer and an initiator into the (methyl) acrylic acid wastewater, converting the (methyl) acrylic acid wastewater into a polymer in a gel form by illumination, and dehydrating and drying to obtain a high-water-absorptivity material. The method for treating the acrylic acid wastewater has the advantages of low energy consumption, high efficiency and simple process, and can realize resource utilization of the wastewater generated in the production of (methyl) acrylic ester.)

1. A method for treating (meth) acrylic acid waste water, characterized by comprising the steps of:

A. adding a vinyl monomer and an initiator into (methyl) acrylic acid wastewater to obtain a solution;

B. irradiating the solution with light to initiate polymerization to obtain a gel polymer;

C. the polymer was separated off.

2. The method of treating (meth) acrylic acid waste water according to claim 1, wherein the (meth) acrylic acid waste water of step A contains one or more of methacrylic acid, acrylic acid, a methacrylate salt or an acrylate salt.

3. The method for treating (meth) acrylic acid waste water according to claim 1, wherein the initiator in the step A comprises a radical type photoinitiator.

4. The method for treating (meth) acrylic acid waste water according to claim 1, wherein the vinyl monomer in the step A comprises monofunctional acrylic acid, acrylamide, vinyl sulfonate, and polyfunctional vinyl monomer.

5. The method for treating (meth) acrylic acid waste water according to claim 4, wherein the amount of the monofunctional vinyl monomer added is 0 to 30 w% based on the amount of the waste water; the addition amount of the multifunctional vinyl monomer is 0-5 w% of the amount of the wastewater.

6. The method for treating (meth) acrylic acid waste water according to claim 2, wherein the content of methacrylic acid, acrylic acid, methacrylate or acrylate in the acrylic acid waste water is 1 w% to 20 w% based on the mass of the aqueous solution.

7. The method for treating (meth) acrylic acid waste water according to claim 1 or 3, wherein the photoinitiator is sensitive to light in a wavelength range of 280nm to 410nm, and the amount of the photoinitiator is 0.08 w% to 2 w% based on the mass of the solution.

8. The method for treating (meth) acrylic acid waste water according to claim 1, wherein the light source for light irradiation to initiate polymerization in the step B comprises a UV lamp or an LED lamp, and the light source emits light having a wavelength of 280nm to 415 nm.

Technical Field

Background

The (meth) acrylic acid contained in the industrial wastewater generated in the production of (meth) acrylic esters is difficult to biodegrade, the treatment cost of the direct incineration method is too high, and the discharge after dilution causes huge damage to the water environment, so that harmless treatment is required. The treatment methods for (meth) acrylic acid-based wastewater include three methods of physical, chemical and biological methods, all of which require multi-step treatment that is time-consuming and high in running cost.

The prior treatment mode, application No. CN201710930729.2, application No. 20171009 patent of invention, discloses a comprehensive treatment method of acrylic ester production wastewater, which comprises the steps of adding at least one chain transfer agent of aliphatic mercaptan, carbon tetrachloride, sodium formate, inorganic phosphate, octanol, isopropanol, propanol or butanol, adding at least two radical initiators of ammonium persulfate, sodium persulfate, potassium persulfate, sodium bisulfite, ammonium bisulfite, potassium bisulfite, hydrogen peroxide, ferrous chloride, cumene hydroperoxide or benzoyl peroxide, carrying out polymerization reaction at 45-85 ℃ for 4-9 hours, filtering with a sodium filtration/ultrafiltration membrane, or adding an organic solvent to precipitate a polymer, filtering and separating to obtain a solid serving as a scale inhibitor, fractionating a liquid part to obtain an organic solvent, and concentrating and incinerating the residual wastewater. However, polyacrylic acid obtained by the chemical treatment has low molecular weight, and wastewater is difficult to separate.

Further, an invention patent with application No. CN201510595251.3, filed No. 20150917, discloses a method for photocatalytic treatment of acrylic ester wastewater, which employs a high-pressure mercury lamp or a KrF ultraviolet excimer laser with a main wavelength of 254nm to irradiate the wastewater treated with persulfate or hydrogen peroxide, then adds a polyvalent metal ion compound as a precipitant to flocculate the acrylic acid polymer in the wastewater, and then filters out the precipitate, wherein the removal rate of acrylic acid in the wastewater is about 77% -88%. Although the treatment process is greatly simplified, the acrylic acid in the wastewater is not recycled.

Disclosure of Invention

The invention aims to: aiming at the existing problems, the invention provides a method for treating (methyl) acrylic acid wastewater, which has the advantages of low energy consumption, high efficiency and simple process, adopts photopolymerization to convert methacrylic acid, acrylic acid, methacrylate or acrylate in the (methyl) acrylic acid wastewater into a polymer in a gel form, and then dehydrates and dries the polymer to obtain the super absorbent resin which can be used as a super absorbent material required by moisture retention, water absorption and water prevention in the aspects of environmental protection, agriculture, forestry and the like.

The technical scheme adopted by the invention is as follows:

the method for treating (meth) acrylic acid wastewater of the present invention comprises the steps of:

A. adding a vinyl monomer and an initiator into (methyl) acrylic acid wastewater to obtain a solution;

B. irradiating the solution with light to initiate polymerization to obtain a gel polymer;

C. the polymer was separated off.

In the above method, the (meth) acrylic acid waste water in step a refers to fractional distillation waste water generated during the esterification reaction of acrylic acid or methacrylic acid, and a washing liquid generated by washing the esterification reaction product with caustic soda, soda ash or potassium hydroxide solution, wherein the washing liquid mainly contains one or more of methacrylic acid, acrylic acid, methacrylate or acrylate, and methacrylate or acrylate mainly refers to sodium salt or potassium salt thereof. The wastewater contains not only methacrylic acid, acrylic acid, methacrylate or acrylate but also a catalyst for esterification, a stabilizer, a raw material alcohol and a product (meth) acrylate, and is complicated in composition. Direct thermal polymerization, such as the disclosed process mentioned in the above section, produces little gel and is difficult to separate directly, and the product does not possess high water absorption properties and is not a useful superabsorbent material. The applicant finds that methacrylic acid, acrylic acid, methacrylate and acrylate in the wastewater can be conveniently and efficiently converted into gel products by adopting a photopolymerization method in one step, and the gel products are further dehydrated and dried to form super absorbent resin which can be used as a super absorbent material, and the water produced by dehydration and drying can be returned to production and use, so that the harmless and recycling treatment and use of the wastewater are realized.

Furthermore, the content of methacrylic acid, acrylic acid, methacrylate or acrylate in the (meth) acrylic acid wastewater is 1 w-20 w% of the mass of the aqueous solution, and the content of methacrylic acid, acrylic acid, methacrylate or acrylate varies greatly depending on the production process and the raw materials used for the esterification reaction. The addition of water soluble vinyl monomer can promote the photopolymerization of waste water, regulate and raise the water absorbing performance, and the gel polymer is easy to separate and has high water absorbing performance. Suitable vinyl monomers include monofunctional monomers such as acrylamide, acrylic acid and salts thereof, methacrylic acid and salts thereof, vinyl and substituted vinyl sulfonic acids and salts thereof; small amounts of polyfunctional vinyl monomers may also be added to control the degree of crosslinking of the resulting polymer, such as methylene bisacrylamide, ethylene glycol diallyl ether, diethylene glycol diallyl ether, butanediol diallyl ether, polyglycol diallyl ether, trimethylolpropane triallyl ether, ethoxylated trimethylolpropane triallyl ether and the like. The dosage of the monofunctional vinyl monomer can reach 0-30 w%, preferably 0-20 w% of the wastewater, and excessive addition of the monofunctional vinyl monomer causes the utilization value of methacrylic acid, acrylic acid, methacrylate and acrylate in the wastewater to be low; the amount of polyfunctional monomer used should not be too large, which would affect the water absorption properties of the product, and is preferably in the range of 0 to 5% w of the amount of waste water.

Further, the photoinitiator is a photoinitiator which generates free radicals after illumination, and comprises: aryl ketones, such as substituted and unsubstituted benzophenones, for example: 4-hydroxybenzophenone, 4- (2-hydroxyethyl) -oxybenzophenone, 4-hydroxyfluorenone, 4- (2-hydroxyethyl) -oxyfluorenone, biphenyl benzophenone, fluorenone, naphthyl phenyl ketone, camphorone, thioxanthone, and the like; substituted and unsubstituted benzoin ethers, 2-hydroxy-2-methyl-1-phenyl-propanone-1, 1-hydroxy-cyclohexyl-phenyl-ketone, 2-dimethoxy-, 2-diphenylethan-1-one, 2-hydroxy-4' - (2-hydroxyethoxy) -2-methylpropiophenone, 2,4, 6-trimethylbenzoyl-diphenylphosphine oxide, bis (2,4, 6-trimethylbenzoyl) -phenylphosphine oxide, and the like, and combinations thereof. The photoinitiator may be dissolved in the vinyl monomer or a small amount of solvent, such as ethanol, acetone, etc., and then added to the photopolymerization solution. Preferably a photoinitiator sensitive to the wavelength range of 280-410nm, and the dosage of the photoinitiator is 0.08-2 w percent of the mass of the wastewater.

Preferably, the waste water and the aqueous solution added with the vinyl monomer, particularly the acrylic acid or the methacrylic acid, can be neutralized by alkaline solution, so that the pH value of the waste water is 4-10, the acid neutralization degree of the waste water is more than 60 percent, the corrosivity of the waste water on equipment is reduced, and the water absorption rate and the water absorption speed of the obtained polymer as the super absorbent resin are adjusted and controlled.

Further, since the photopolymerization reaction is fast, the photopolymerization and the thermal polymerization can be combined and sequentially performed as the temperature of the system increases as the polymerization proceeds, thereby increasing the degree of the polymerization. In one embodiment, a photoinitiator and a thermal initiator are added simultaneously, the temperature of the system is automatically raised by using the polymerization heat of the photopolymerization reaction, and the thermal initiator is started to initiate the polymerization of the remaining monomers, so that the conversion rate of the methacrylic acid, the acrylic acid, the methacrylate and the acrylate in the system and the added vinyl monomer is increased. Water soluble thermal initiators may be used, including persulfates, such as ammonium persulfate, sodium persulfate, potassium persulfate, hydrogen peroxide, and water soluble azo initiators, such as the agents azobisisobutylamidine hydrochloride, azobisisobutylimidazoline hydrochloride, azobiscyanovaleric acid, azobisdiisopropylimidazoline. For persulfate and hydrogen peroxide, reducing agents can be compounded to properly reduce the onset temperature of the initiator, and usable reducing agents include sulfite, ferrous chloride and the like, and the use method and the use amount of the reducing agents can be inquired by a person skilled in the art from related information.

Further, the light source used for initiating polymerization by light irradiation includes UV lamp and LED lamp, including polar and electrodeless mercury lamp, low-pressure fluorescent lamp, moth-killing lamp, germicidal lamp, plate-burning lamp, etc., preferably including UV lamp or LED lamp with emission wavelength of 280-. As a preferred embodiment, before the irradiation with light, an inert gas such as nitrogen, argon or the like may be introduced to remove oxygen, so that the oxygen content in the solution should be less than 100ppm, in particular less than 50ppm, and then the methacrylic acid, acrylic acid, methacrylate or acrylate or the like in the waste water is polymerized by the irradiation with light.

In summary, the advantages of the method for treating (meth) acrylic acid wastewater of the present invention are manifold:

1. the photopolymerization is used for decomposing the thermal initiator instead of heating to initiate polymerization, so that the efficiency is high, the operation is convenient, the heating step is omitted, the energy consumption is saved, the treatment cost of the waste water is reduced, and the energy-saving effect is very obvious when a large amount of (methyl) acrylic acid waste water is treated;

2. the photopolymerization speed is high, the photopolymerization is usually completed within tens of seconds to minutes, the efficiency is high, and the conversion rate of methacrylic acid, acrylic acid, methacrylate or acrylate in wastewater is high;

3. the photopolymerization treatment process for the wastewater is easy to control, and the product is gel and is convenient to separate;

4. the polymerization product obtained by photopolymerization has high water absorption property, the water absorption multiplying power is more than 30, the polymerization product can be used as a water retention and water absorption material, the resource utilization of waste water is realized, and the polymerization product can be used as a water retention agent for agricultural planting, soil improvement, road slope treatment, water prevention, leakage stoppage and the like.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

The following examples used 3 wastewaters from chemical plants for the production of (meth) acrylic acid esters, wastewater 1 having a sodium acrylate content of about 14.3 w%, a COD value of 104000, a pH value of 10, wastewater 2 having an acrylic acid content of about 1.2 w%, a COD value of about 9000 and a pH value of less than 2; the content of sodium methacrylate in the wastewater 3 is about 16w percent, the COD value is about 110000, and the pH value is 9; the dosage of the wastewater 1, the wastewater 2 and the wastewater 3 is 100 g.