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Study On Comprehensive Treatment Of Oxidizing Cyclohexane Wastewater

Posted on:2004-05-22Degree:MasterType:Thesis
Country:ChinaCandidate:X Q HuFull Text:PDF
GTID:2121360122470283Subject:Chemical Engineering
Abstract/Summary:PDF Full Text Request
Cyclohexanone and cyclohexanol are now produced by liquid-phase oxidation of cyclohexane in an industrial scale. The production process, however, gives cyclohexanone and cyclohexanol in a total yield of from about 75% to about 85%. Most of the by-products that formed are discharged from the reactor in the form of waste water after caustic washing, while the other small part comes to the distillation system as the light weight oil and X oil. The wastewater has many characteristics such as a large quantity of discharge, complicated composition and high value of COD. In nowadays, burning or chemical methods are used to treat with the wastewater. Although burning can avoid serious environment pollution by organism, it wastes a great deal of energy and resources. And most of the chemical methods only focus on the recovery of monocarboxylic and dicarboxylic acids. In this thesis, we pay much attention to the disposal of the e-hydroxy-caproic acid and its polymer which hasn't any reasonable reports on its treatment solutions.Based on the e-hydroxycaproic acid and its polymer, we have mainly discussed three procedures which are respectively called as nitric acid oxidation, oxygen oxidation and alkaline fusion. After giving analysis to each advantages and disadvantages, we have decided a new effective procedure with alkaline fusion and some treatments to other organic acids.According to the said procedure, we have also discussed optimum conditions of some key process. Take, for instance, the affecting factors ,process conditions and kinetics characteristics of the alkaline fusion treatment on e-hydroxycaproic and its derivatives are studied. The experiment result demonstrates that the reaction time does the most to the alkaline fusion reaction, and then the temperature, and thequantity of the sodium hydroxide has less importance of the three factors. The optimum process conditions determined by orthogonal test method are as follows: reaction temperature 300℃, sodium hydroxide 6g(based on 150g wastewater), reaction time 6h.Under this condition the content of adipic acid is greatly increased from 3.18% to 8.74% which brings good economic and environmental benefits. We have also studied the best conditions of acidification by sulfuric acid as follows: final pH value is about 2, the concentration of sulfuric acid is 98%, temperature is 20℃. A new method to what-called mashed solid by hot water is put forward. The adipic acid crystal of 97% purity can be gained from the solution from above process under the temperature 1 ℃. And the crystal ratio is 87%. We have also discussed other processes such as extraction and distillation and completed a whole procedure.Through economic analysis, we anticipate to get profit about 1000 yuan per 1 ton wastewater.We firstly complete the process for preparing adipic acid by alkaline fusion of e-hydroxy-caproic acid and its polymers and make a success. This treatment is practical and reasonable which also brings good economic and environmental benefits.
Keywords/Search Tags:oxidizing cyclohexane wastewater, alkaline fusion, e-hydroxycaproic, adipic acid
PDF Full Text Request
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