| Bisphenol A?BPA?is the main raw material of synthetic resin,and is considered as a typical endocrine disruptor,which easily hydrolyze under the condition of high temperature,strong acid and strong base.BPA did not rose a serious attention because of it low concentration.However,researchers have shown that BPA has a detrimental effect on human's immune system.Potassium permanganate?KMnO4?and ozone?O3?could oxidize various organic compounds in aqueous.In this study,the optimal reaction conditions for the degradation of BPA by single O3 and individual KMnO4 were employed by single factor experiment.In addition,the degradation effect of potassium permanganate combined with ozone?KMnO4-O3?on BPA were investigated.Furthermore,the contribution rate of different free radicals in the combined degradation process was analyzed,and the biologic toxicity of BPA degradation intermediates was analyzedThe effects of different factors were also considered.The results are as follows.?1?The optimum conditions for the degradation of BPA by O3 alone and KMnO4 alone are:O3 addition concentration is 3.0 mg·L-1,KMnO4 addition concentration is 100?mol·L-1,pH=9,room temperature.?2?The removal efficiency of BPA treated by solely O3 for 5 minutes was 29.0%under the condition of 100 mg·L-1 BPA,3.0 mg·L-1O3,in pH=9.Only 33.9%BPA was removed after being treated by KMnO4 with 5 minutes and 100?mol·L-11 KMnO4.However,compared with the treatment by O3 or KMnO4,The removal efficiency of BPA treated by KMnO4-O3for 5 minutes was 92.1%,the figure saw an uptrend of the removal efficiency of BPA,increased by 27.8%.Therefore,KMnO4-O3 have a synergistic effect on the degradation of BPA in aqueous.?3?pH can significantly affect the degradation of BPA by KMnO4-O3.Under alkaline conditions,the synergistic effect of KMnO4-O3 degradation BPA is the best.When pH=9 and pH=7,at 5 min,KMnO4-O3 had the best synergistic degradation effect on BPA,and the degradation rate of BPA was 92.1%and 83.5%,respectively,and compared with the treatment by O3 or KMnO4,the degradation rate of BPA increase 27.8%and 23.7%respectively.When pH=7 and pH=3,at 30 min,KMnO4-O3 had the best synergistic degradation effect on BPA,and the degradation rate of BPA was 96.3%and 82.4%respectively,and compared with the treatment by O3 or KMnO4,the degradation rate of BPA increase 14.7%and 13.1%respectively.?4?the adding sequences of KMnO4 and O3 have significant influence on the degradation of BPA.In the condition of neutral solution,BPA was firstly treated by KMnO4in 5 minutes,after which pouring the O3 into the system with 5 min reaction time.Finally,the degradation rate of BPA is 66.2%.However,when KMnO4 and O3 was added at the same time,at 5min,the degradation rate of BPA was 52.9%.?5?TOC experiments pointed out that in circumstance of pH=9 and reaction time was10min,BPA had been approximately completely degraded,with 98.7%,while TOC in the solution has not been completely degraded,at only 66.3%.TOC degradation rate increased to 97.8%until 20 minutes later.?6?Quenching experiments indicated that·OH and Mn7+were major active species for BPA degradation.?7?Biotoxicity experiments showed that more toxic intermediates were likely to be produced during the degradation of BPA.The inhibition rate of luminescent bacteria was the lowest,at only 4%,in the condition of the reaction time was 30 min,?8?GC-MS analysis results illustrated that the main mechanism of the degradation BPA by the KMnO4-O3 system is attacking the adjacent,counterpart of phenol group and the connection between benzene ring and isopropyl,and lead to the formation of organic compounds such as phenylpropionic acid,4-tert-butyl phenol and 4-hydroxypropyl phenol.Finally,those compounds were degraded as H2O and CO2.To summaries,KMnO4-O3 can effectively degrade BPA in water and has synergistic effect.Additionally,the pre-oxidation treatment by KMnO4 can further promote the degradatd efficiency of BPA by KMnO4-O3.This study can be taken reference for degradating the high concentration organic wastewater. |
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