Study On Preparation Of Potassium Ferrate By Electrolysis And Its Application In Advanced Treatment Of Pharmaceutical Wastewater

Due to pharmaceutical wastewater usually having a high concentrated organic,poor biodegradability and toxic substances which could cause permanent damage to humans and the environment,it was considered to be the object needed to treat stressfully.With the improvement of people's awareness of environmental protection,promotion of energy saving and emission reduction work,and introduction of a new discharge standard of water pollutants for pharmaceutical industry,a large number of pharmaceutical enterprises couldn't meet the discharge standard anymore.It was urgent to upgrade the wastewater treatment system for them.In view of the above problem,the secondary effluent from Hubei Guangji Pharmaceutical Company was taken as the research object.The study was divided into two parts.In the first part,not only the optimum preparation conditions for potassium ferrate by electrolysis were discussed,but also the preparation sample was analyzed with qualitative analysis and quantitative analysis.In the second part,in addition to the effect factors and the optimum reaction conditions studied,the degradation mechanism and apparent kinetic equation of 3,4-dimethyl-Benzenamine oxidized by potassium ferrate were explored.The main conclusions are followed:?1?Result indicated the optimum preparation conditions for potassium ferrate by electrolysis were as follows:tassium hydroxide solution was 16 mol/L,anode current density was 50 mA/cm²,electrolysis temperature was 50?,electrolysis time are 5hours.In these conditions,the potassium ferrate concentration of electrolyte in anode room could reach 11.13 g/L.Besides,the purity of preparation sample could raised to93.8%from 84.2%by purification significantly.?2?According to the date of XRD,IR,SEM and EDS,the preparation sample was determined to be 10?m long potassium ferrate containing a little impurities.These impurities may come from iron hydroxide by decomposition of potassium ferrate,absorbed crystal water and crystal water,and residue from detergent.?3?Accrding to the dates from orthogonal experimental methods and range analysis methods,it was conclude that the effect factors were the dosage of potassium ferrate>initial pH value>reaction time>reaction temperature.The dosage of potassium ferrate was the most important factor affecting the treatment effect.In the condition that the dosage of potassium ferrate was 3 g/g COD_cr,pH value was 5,Oxidize the wastewater for 20 min at 20?,the removal efficiency and concentration of COD_crr could achieve 75.30%and reduce to 180.2 mg/L,respectively.The quality of effluent could meet the new discharge standard of water pollutants for pharmaceutical industry.?4?Based on GC/MS spectrum of degradation solution of 3,4-dimethyl-Benzen-amine,through reviewing related literatures at home and abroad,it was presumed that3,4-dimethyl-Benzenamine converted to 2,4-dimethyl-Benzenamine at first.Then the4-Nitroisophthalic acid was formed by amide and methyl oxidized successively.By decarboxylation,4-Nitroisophthalic acid was oxidized to nitrobenzene.Next,the nitr-obenzene was oxidized to benzoquinone or benzene cation,and then decomposes into a series of small molecular hydrocarbons by phenyl structure destroyed.In final,these hydrocarbons were degrade into carbon dioxide and water.?5?The reaction that potassium ferrate oxidize 3,4-dimethyl-Benzenamine was1.7334 grade.Its apparent kinetic equation was r=0.0043C_A^0.4855C_B^1.2479.This indicated that 3,4-dimethyl-Benzenamine was more difficult degrade than phenol.