| In the production process of polyether ether ketone,a large amount of pure water is used as a solvent,so a corresponding amount of industrial wastewater will be produced.The waste water includes high concentration of acetone,sodium fluoride,trace amounts of polyether ether ketone,diphenyl sulfone,etc.The direct discharge of this water will cause greater harm to the environment,especially the concentration of acetone and sodium fluoride is much higher than 10000 mg/L,and direct discharge is not allowed,so it needs to be treated.The treated COD(mainly acetone)should be less than 80 mg/L,and the fluoride ion concentration should be less than 10 mg/L.According to the composition and temperature of the wastewater,after a period of exploration,the corresponding experimental method was determined.Through molecular distillation,most of the acetone is recovered to reduce the COD concentration in the water to about 2.5%of the original concentration;calcium chloride is added,and then filtered through a plate and frame to reduce the F~-concentration in the water to below 10 mg/L;The COD in the water is further reduced;finally,the COD is reduced to below 80mg/L through activated carbon adsorption,and the fluoride ion concentration is less than 8 mg/L.According to the experimental process and the continuity of the treatment,the water treatment process and the structure of the main equipment molecular distillation tower are determined.Molecular distillation mainly investigated the effects of feed temperature,feed volume,evaporator temperature,film scraping speed and different distillation times on COD removal rate.When the feed temperature is 32℃,the feed rate is 600 ml/h,the evaporator temperature is 33℃,the film scraping speed is 160 r/min,and the number of distillations is four,the total recovery rate of acetone is 97.7%.The water after molecular distillation was added with calcium chloride to form calcium fluoride precipitate,which was filtered with a plate and frame filter.As a result,the fluoride ion concentration dropped to 7.8 mg/L on average,and the F-ion removal rate reached 99%.Infrared spectroscopy analysis of the filter cake showed that the trace solid organic matter polyether ether ketone and diphenyl sulfone were removed.Scanning electron microscopy shows that the filter cake has a dense structure and regular morp Hology,forming a dense filter layer,which is more conducive to the retention of fine particles.Through thermogravimetric analysis,the weight loss of the filter cake was 3.9%,which was determined to be the weight loss of combined water and organic matter.Electric hydroxyl oxidation mainly investigates the effects of reaction time,current density,p H and potential difference on COD removal rate.At p H=6,oxygen input is 1L/min,current density is 11.4 m A/cm~2,and treatment time is 80 min.The COD removal rate is 80%.Activated carbon is used to adsorb the water treated by hydroxyl oxidation,the salt solution and the salt solution are added to reach the adsorption equilibrium after 90minutes,the COD removal rate is 98%,and the remaining COD is about 4 mg/L.When the adsorption time is 45 min,COD The concentration is less than 80 mg/L.Activated carbon is hydrolyzed and absorbed by heat,and reaches the desorption equilibrium after 120 min.After the activated carbon is regenerated,it is re-adsorbed,and the COD removal rate is96%.The kinetics of acetone adsorption by activated carbon has a higher degree of fit with the quasi-first-order adsorption model,indicating that the adsorption process is mainly physical adsorption.According to the experimental process and results,the wastewater treatment process was designed,and the molecular distillation tower was designed according to the number of molecular distillation and the water condition,which made the equipment structure more reasonable and the process more compact.Compared with traditional water treatment methods,a large amount of acetone is recovered;calcium fluoride that can be reused is obtained;and the water treatment time is greatly shortened. |
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