阅读说明：本技术 一种利用生产丙烯酸树脂所产生的废水制备低分子量聚丙烯酸钠的方法 (Method for preparing low-molecular-weight sodium polyacrylate by using wastewater generated in production of acrylic resin ) 是由 张丽丽 林翔云 张越炜 姚晓峰 于 2020-12-28 设计创作，主要内容包括：本发明提供了一种利用生产丙烯酸树脂所产生的废水制备低分子量聚丙烯酸钠的方法,涉及工业废水回收技术领域。本发明将生产丙烯酸树脂所产生的废水用氢氧化钠或碳酸钠调节pH值至7.5～8.5后过滤除杂,将所得滤液进行减压蒸发浓缩,得到丙烯酸钠浓缩液；将所述丙烯酸钠浓缩液、亚硫酸氢钠和过硫酸铵混合,在60～70℃条件下进行聚合反应,得到反应料液；将反应料液冷却后调节pH值至7.0～7.5,得到低分子量聚丙烯酸钠溶液。本发明利用生产丙烯酸树脂所产生的废水制备低分子量聚丙烯酸钠,充分利用了废水中的丙烯酸和丙烯酸钠资源,增加了废水的附加价值。此外,本发明过程简单,能耗低,降低了废水的处理成本,适合工业化生产。(The invention provides a method for preparing low molecular weight sodium polyacrylate by using wastewater generated in the production of acrylic resin, and relates to the technical field of industrial wastewater recovery. Adjusting the pH value of wastewater generated in the production of acrylic resin to 7.5-8.5 by using sodium hydroxide or sodium carbonate, filtering to remove impurities, and performing reduced pressure evaporation and concentration on the obtained filtrate to obtain a sodium acrylate concentrated solution; mixing the sodium acrylate concentrated solution, sodium bisulfite and ammonium persulfate, and carrying out polymerization reaction at the temperature of 60-70 ℃ to obtain a reaction feed liquid; and cooling the reaction liquid, and adjusting the pH value to 7.0-7.5 to obtain the low molecular weight sodium polyacrylate solution. The method utilizes the wastewater generated in the production of the acrylic resin to prepare the low molecular weight sodium polyacrylate, fully utilizes the resources of acrylic acid and sodium acrylate in the wastewater, and increases the added value of the wastewater. In addition, the method has the advantages of simple process and low energy consumption, reduces the treatment cost of the wastewater, and is suitable for industrial production.)

1. A method for preparing low molecular weight sodium polyacrylate by using wastewater generated in the production of acrylic resin is characterized by comprising the following steps:

(1) adjusting the pH value of wastewater generated in the production of acrylic resin to 7.5-8.5 by using sodium hydroxide or sodium carbonate, filtering to remove impurities, and performing reduced pressure evaporation and concentration on the obtained filtrate to obtain a sodium acrylate concentrated solution; the mass content of sodium acrylate in the sodium acrylate concentrated solution is more than or equal to 40 percent;

(2) mixing the sodium acrylate concentrated solution, sodium bisulfite and ammonium persulfate, and carrying out polymerization reaction at the temperature of 60-70 ℃ to obtain a reaction feed liquid;

(3) and cooling the reaction liquid, and adjusting the pH value to 7.0-7.5 to obtain the low molecular weight sodium polyacrylate solution.

2. The method according to claim 1, wherein the mass ratio of the sodium acrylate concentrated solution, the sodium bisulfite and the ammonium persulfate in the step (2) is 100: 1.0-10.0: 0.02 to 0.15.

3. The method according to claim 1 or 2, wherein the ammonium persulfate in the step (2) is added in the form of an aqueous ammonium persulfate solution with a mass concentration of 10%.

4. The method according to claim 3, wherein the aqueous solution of ammonium persulfate is added in a dropwise manner at a rate of 0.3 to 0.4 kg/h.

5. The method according to claim 1 or 2, wherein the time for the polymerization reaction in the step (2) is 1.5-2.5 h.

6. The method according to claim 1, wherein the reaction solution in the step (3) is cooled to 35-45 ℃.

7. The method according to claim 1, wherein the pH adjusting agent for adjusting the pH value in the step (3) is an aqueous solution of sodium hydroxide; the mass concentration of the sodium hydroxide aqueous solution is 30%.

8. The method as claimed in claim 1, wherein the molecular weight of the sodium polyacrylate in the low molecular weight sodium polyacrylate solution in the step (3) is 500-5000.

Technical Field

The invention relates to the technical field of industrial wastewater recovery, in particular to a method for preparing low molecular weight sodium polyacrylate by using wastewater generated in the production of acrylic resin.

Background

Acrylic resin is an important chemical raw material, and is mainly used for manufacturing photocureable coatings, photocureable ink, photoresists, flexible printed matters, solder resists, paints, modified polymers and the like. When the acrylic resin is produced, a large amount of waste water (referred to as acrylic acid waste water) is generated, the COD value of the waste water is high, and the waste water contains toxic and harmful substances, such as heavy metals, inorganic salts and the like, which seriously pollute the environment. In the prior art, acrylic resin manufacturers generally discharge waste water after complex physical and chemical and microbial treatment reaches the standard, but the physical and chemical and microbial treatment is labor-consuming and time-consuming and consumes more energy; or the waste water is evaporated and concentrated to obtain a solid which has no value and can not be decomposed in the soil, and the solid is transported to a remote area for landfill, the treatment mode is easy to cause secondary pollution, and the concentration to the solid needs to consume a large amount of energy, so that the treatment cost is extremely high. Moreover, physical and chemical treatment, microbial treatment and concentration landfill all cause great resource waste.

Disclosure of Invention

In view of the above, the present invention aims to provide a method for preparing low molecular weight sodium polyacrylate by using wastewater generated in the production of acrylic resin. The method provided by the invention has the advantages of simple process and low cost, and fully utilizes the acrylic acid wastewater resource, increases the additional value of the acrylic acid wastewater, and avoids the pollution to the environment.

In order to achieve the above object, the present invention provides the following technical solutions:

the invention provides a method for preparing low molecular weight sodium polyacrylate by using wastewater generated in the production of acrylic resin, which comprises the following steps:

(1) adjusting the pH value of wastewater generated in the production of acrylic resin to 7.5-8.5 by using sodium hydroxide or sodium carbonate, filtering to remove impurities, and performing reduced pressure evaporation and concentration on the obtained filtrate to obtain a sodium acrylate concentrated solution; the mass content of sodium acrylate in the sodium acrylate concentrated solution is more than or equal to 40 percent;

(2) mixing the sodium acrylate concentrated solution, sodium bisulfite and ammonium persulfate, and carrying out polymerization reaction at the temperature of 60-70 ℃ to obtain a reaction feed liquid;

(3) and cooling the reaction liquid, and adjusting the pH value to 7.0-7.5 to obtain the low molecular weight sodium polyacrylate solution.

Preferably, the mass ratio of the sodium acrylate concentrated solution, the sodium bisulfite and the ammonium persulfate in the step (2) is 100: 1.0-10.0: 0.02 to 0.15.

Preferably, the ammonium persulfate in the step (2) is added in the form of an ammonium persulfate aqueous solution, and the mass concentration of the ammonium persulfate aqueous solution is 10%.

Preferably, the ammonium persulfate aqueous solution is added in a dropwise manner, and the dropwise adding speed is 0.3-0.4 kg/h.

Preferably, the time of the polymerization reaction in the step (2) is 1.5-2.5 h.

Preferably, the reaction solution in the step (3) is cooled to 35-45 ℃.

Preferably, the pH value adjusting agent used in the step (3) is a sodium hydroxide aqueous solution; the mass concentration of the sodium hydroxide aqueous solution is 30%.

Preferably, the molecular weight of the sodium polyacrylate in the low molecular weight sodium polyacrylate solution in the step (3) is 500-5000.

The invention provides a method for preparing low molecular weight sodium polyacrylate by using wastewater generated in the production of acrylic resin, which comprises the following steps: (1) adjusting the pH value of wastewater generated in the production of acrylic resin to 7.5-8.5 by using sodium hydroxide or sodium carbonate, filtering to remove impurities, and performing reduced pressure evaporation and concentration on the obtained filtrate to obtain a sodium acrylate concentrated solution; the mass content of sodium acrylate in the sodium acrylate concentrated solution is more than or equal to 40 percent; (2) mixing the sodium acrylate concentrated solution, sodium bisulfite and ammonium persulfate, and carrying out polymerization reaction at the temperature of 60-70 ℃ to obtain a reaction feed liquid; (3) and cooling the reaction liquid, and adjusting the pH value to 7.0-7.5 to obtain the low molecular weight sodium polyacrylate solution. The invention utilizes the waste water generated by producing acrylic resin to prepare low molecular weight sodium polyacrylate, fully utilizes acrylic acid and sodium acrylate resources in the waste water, increases the added value of the waste water generated by producing acrylic resin, can be widely used as flocculating agent, boiler scale prevention and inhibition agent, pigment dispersing agent, chemical fiber sizing agent, metal material quenching agent, detergent auxiliary agent, granular pesticide carrier and the like, can also be widely applied to the aspects of metal recovery of printing industry, plastic industry, medicine, pharmacy and metal ion waste liquid and the like, and avoids the pollution to the environment while avoiding the waste of resources. In addition, the method provided by the invention has the advantages of simple process and low energy consumption, reduces the treatment cost of the wastewater, and is suitable for industrial production.

Detailed Description

The invention provides a method for preparing low molecular weight sodium polyacrylate by using wastewater generated in the production of acrylic resin, which comprises the following steps:

(1) adjusting the pH value of wastewater generated in the production of acrylic resin to 7.5-8.5 by using sodium hydroxide or sodium carbonate, filtering to remove impurities, and performing reduced pressure evaporation and concentration on the obtained filtrate to obtain a sodium acrylate concentrated solution; the mass content of sodium acrylate in the sodium acrylate concentrated solution is more than or equal to 40 percent;

(2) mixing the sodium acrylate concentrated solution, sodium bisulfite and ammonium persulfate, and carrying out polymerization reaction at the temperature of 60-70 ℃ to obtain a reaction feed liquid;

(3) and cooling the reaction liquid, and adjusting the pH value to 7.0-7.5 to obtain the low molecular weight sodium polyacrylate solution.

The method comprises the steps of adjusting the pH value of wastewater generated in the production of acrylic resin to 7.5-8.5 by using sodium hydroxide or sodium carbonate, filtering to remove impurities, and carrying out reduced pressure evaporation and concentration on the obtained filtrate to obtain a sodium acrylate concentrated solution. In the invention, the wastewater generated by producing the acrylic resin contains a large amount of acrylic acid and sodium acrylate, and impurities such as iron ions, copper ions, methanesulfonic acid and the like, which cause that subsequent polymerization reaction can not be carried out or cause 'implosion', the pH value of the wastewater is adjusted to 7.5-8.5, preferably 8.0 by using sodium hydroxide or sodium carbonate, the wastewater is reacted with the impurities such as iron and copper to generate iron hydroxide, copper hydroxide, iron carbonate, basic iron carbonate, copper carbonate, basic copper carbonate and the like, and the solubility of the substances in water is extremely low, so that the substances are easy to precipitate, filter and remove; the methanesulfonic acid reacts with sodium hydroxide or sodium carbonate to generate sodium methanesulfonate which remains in the filtrate without affecting the polymerization reaction. The method for filtering is not particularly required by the invention, and the filtering method well known to the technicians in the field can be adopted; according to the invention, through the filtration, impurity precipitates such as iron hydroxide, copper hydroxide, iron carbonate, basic iron carbonate, copper carbonate, basic copper carbonate and the like are filtered out. In the invention, the mass content of sodium acrylate in the sodium acrylate concentrated solution is more than or equal to 40%, preferably 40-42%; the mass content of the sodium acrylate in the sodium acrylate concentrated solution is controlled to be more than 40 percent, which is beneficial to the subsequent polymerization reaction; the present invention has no special requirement on the specific operation method of the reduced pressure evaporation concentration, and the corresponding method well known to those skilled in the art can be adopted. According to the invention, the filtrate is concentrated to the concentrated solution with the mass content of sodium acrylate more than or equal to 40%, and compared with the operation of concentrating the wastewater to solid matters in the wastewater treatment by a concentration landfill method, the energy consumption of concentration is greatly reduced, so that the cost for treating the wastewater generated in the production of acrylic resin is reduced.

After obtaining the sodium acrylate concentrated solution, mixing the sodium acrylate concentrated solution, sodium bisulfite and ammonium persulfate, and carrying out polymerization reaction at the temperature of 60-70 ℃ to obtain a reaction feed liquid. In the present invention, the mass ratio of the sodium acrylate concentrated solution, the sodium bisulfite and the ammonium persulfate is preferably 100: 1.0-10.0: 0.02 to 0.15, more preferably 100: 4-6: 0.05 to 0.12. In the present invention, the ammonium persulfate is preferably added in the form of an ammonium persulfate aqueous solution, the mass concentration of the ammonium persulfate aqueous solution is preferably 10%, and the addition amount of the ammonium persulfate aqueous solution is based on the mass ratio of the sodium acrylate concentrated solution, the sodium bisulfite and the ammonium persulfate which satisfies the above, that is, when the mass concentration of the ammonium persulfate aqueous solution is preferably 10%, the mass ratio of the sodium acrylate concentrated solution, the sodium bisulfite and the ammonium persulfate aqueous solution is preferably 100: 1.0-10.0: 0.2 to 1.5. In the present invention, the method for mixing the sodium acrylate concentrated solution, the sodium bisulfite and the ammonium persulfate is preferably as follows: and heating the sodium acrylate concentrated solution to 60-70 ℃, preserving heat, and then sequentially adding sodium bisulfite and ammonium persulfate aqueous solution into the sodium acrylate concentrated solution. In the invention, the ammonium persulfate aqueous solution is preferably added in a dropwise manner, and the dropwise adding speed is preferably 0.3-0.4 kg/h. In the invention, the time of the polymerization reaction is preferably 1.5-2.5 h, more preferably 2h, and the time of the polymerization reaction is calculated from the completion of the dropwise addition of the ammonium persulfate aqueous solution. In the polymerization reaction, sodium bisulfite and ammonium persulfate form a redox system, which is favorable for the smooth proceeding of the polymerization reaction; and (3) carrying out polymerization reaction on sodium acrylate in the sodium acrylate concentrated solution under the action of sodium bisulfite and ammonium persulfate to generate sodium polyacrylate, thus obtaining reaction feed liquid (viscous liquid). In the invention, the color of the reaction liquid is light yellow.

After reaction feed liquid is obtained, the pH value of the reaction feed liquid is adjusted to 7.0-7.5 after the reaction feed liquid is cooled, and then the low-molecular-weight sodium polyacrylate solution is obtained. In the invention, the reaction liquid is preferably cooled to 35-45 ℃; the cooling method of the present invention is not particularly limited, and a cooling method known to those skilled in the art, such as natural cooling, may be employed. In the present invention, the pH adjusting agent for adjusting pH is preferably an aqueous sodium hydroxide solution; the mass concentration of the sodium hydroxide aqueous solution is preferably 30%; according to the invention, the pH value of the cooled reaction liquid is adjusted to 7.0-7.5, and the pH value is slightly changed after the polymerization reaction, so that the pH value needs to be further adjusted after the polymerization reaction, so that the influence of acidity or strong basicity on the finished product on the application is avoided. In the invention, the molecular weight of the sodium polyacrylate in the low molecular weight sodium polyacrylate solution is preferably 500-5000.

The method provided by the invention has the advantages of simple process and low cost, and fully utilizes the acrylic acid wastewater resource, increases the additional value of the acrylic acid wastewater, and avoids the pollution to the environment.

The method for preparing low molecular weight sodium polyacrylate by using waste water generated in the production of acrylic resin according to the present invention will be described in detail with reference to the following examples, but they should not be construed as limiting the scope of the present invention.

Example 1

(1) Adjusting the pH value of wastewater generated in the production of acrylic resin to 7.5-8.5 by using sodium hydroxide, filtering out precipitates, and concentrating by reduced pressure evaporation until the mass content of sodium acrylate is 40-42% to obtain a sodium acrylate concentrated solution;

(2) heating 100kg of sodium acrylate concentrated solution to 70 ℃ and preserving heat, adding 5.0kg of sodium bisulfite, dropwise adding 1.0kg of 10 wt% ammonium persulfate aqueous solution for 3 hours, and reacting at constant temperature for 2 hours after the dropwise addition is finished to obtain light yellow viscous liquid;

(3) and cooling the light yellow viscous liquid to 40 ℃, and neutralizing the light yellow viscous liquid to the pH value of 7.0-7.5 by using 30 wt% of sodium hydroxide aqueous solution to obtain the low molecular weight sodium polyacrylate solution. 89.3kg of the low-molecular-weight sodium polyacrylate solution obtained had a solids content of 35.7% by weight, the sodium polyacrylate having an average molecular weight of 2866.

Example 2

(1) Adjusting the pH value of wastewater generated in the production of acrylic resin to 7.5-8.5 by using sodium hydroxide, filtering out precipitates, and concentrating by reduced pressure evaporation until the mass content of sodium acrylate is 40-42% to obtain a sodium acrylate concentrated solution;

(2) heating 100kg of sodium acrylate concentrated solution to 70 ℃ and preserving heat, adding 4.0kg of sodium bisulfite, dropwise adding 1.2kg of 10 wt% ammonium persulfate aqueous solution for 3 hours, and reacting at constant temperature for 2 hours after the dropwise addition is finished to obtain light yellow viscous liquid;

(3) and cooling the light yellow viscous liquid to 40 ℃, and neutralizing the light yellow viscous liquid to the pH value of 7.0-7.5 by using 30 wt% of sodium hydroxide aqueous solution to obtain the low molecular weight sodium polyacrylate solution. 88.9kg of the low-molecular-weight sodium polyacrylate solution having a solids content of 36.1% and an average molecular weight of 2954 were obtained.

Example 3

(1) Adjusting the pH value of wastewater generated in the production of acrylic resin to 7.5-8.5 by using sodium carbonate, filtering out precipitates, and concentrating by reduced pressure evaporation until the mass content of sodium acrylate is 40-42% to obtain a sodium acrylate concentrated solution;

(2) heating 100kg of sodium acrylate concentrated solution to 70 ℃ and preserving heat, adding 6.0kg of sodium bisulfite, dropwise adding 1.1kg of 10 wt% ammonium persulfate aqueous solution for 3 hours, and reacting at constant temperature for 2 hours after the dropwise addition is finished to obtain light yellow viscous liquid;

(3) and cooling the light yellow viscous liquid to 40 ℃, and neutralizing the light yellow viscous liquid to the pH value of 7.0-7.5 by using 30 wt% of sodium hydroxide aqueous solution to obtain the low molecular weight sodium polyacrylate solution. 90.2kg of the obtained low-molecular-weight sodium polyacrylate solution has the solid content of 35.9 percent, wherein the average molecular weight of the sodium polyacrylate is 2770.

The method provided by the invention has the advantages of simple process and low energy consumption, and the low molecular weight sodium polyacrylate is prepared by fully utilizing the wastewater resource generated by producing the acrylic resin, so that the additional value of the acrylic acid wastewater is increased, and the environmental pollution is avoided.

The foregoing is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, various modifications and decorations can be made without departing from the principle of the present invention, and these modifications and decorations should also be regarded as the protection scope of the present invention.