Studies On The Detection And Removal Of Perfluorooctanoic Acid

With the progress of manufacture and the development of science,the living standards of our people have been improved continuously.At the same time,because of the lack of safety precaution,global environmental problems have occurred,which greatly influences the reproduction of creatures and normal life of human beings.Among them,Perfluorochemicals(PFCs)are the representative one.Because of their specific characteristics such as high stability,high interfacial activity,hydrophobic and oleophobic performance,PFCs have been widely used as fire extinguishants,detergents,food packaging and so on in the past 60 years.Studies have shown that PFCs have the feature of persistence and bioaccumulation of which the accumulative levels are hundreds and thousands times higher than some known POPs(persistent organic pollutants)such as OCPs(organochlorine pesticides)and Dioxin.As the most representative perfluorochemicals,perfluorooctanoic acid(PFOA)has been detected in different biological matrixs,wildlife even human blood.It has been demonstrated that PFOA is closely related to birth defects,infertility,immunodeficiencies and so on.Therefore,it is urgent to develop facile and effective strategies to detect and remove PFOA.Based on the above understaning,the research contents of this paper are as follows:1.Nanostructured Indium oxide(In2O3)materials have been fabricated using a facile chemical synthesis approach.Combined with the molecular imprinted technology,a novel photoelectrochemical sensor was constructed using the molecularly imprinted polymer(MIP)modified In2O3/FTO material as the photoactive electrode(denoted as MIP@In2O3/FTO).X-raydiffraction(XRD),electrochemical impedance spectra(EIS),scanning electron microscopy(SEM)and infrared spectroscopy(IR)were used to characterize the as-prepared PEC probe.PEC analysis and practical applications of the sensor were investigated,which showed the high sensitivity and selectivity for the detection of PFOA.2.Effective complete mineralization of PFOA and simultaneous defluorination was achieved by the married photolytic system of nitrate and isopropanol.It was found that by irradiating the solution containing NaNO3 and isopropanol as a typical hydroxyl radical scavenger,the produced higher flux of nitrogen dioxide radical(·NO2)should be responsible for the complete mineralization of PFOA,while only either nitrate or isopropanol could not accomplish efficient degradation of PFOA,exhibiting a greatly synergistic degradation effects for the decomposition of PFOA.The generation of near-stoichiometric equivalents of fluoride released and neglectable pretty small amounts of intermediates suggest that PFOA may be mineralized by the married photolytic system of nitrate and isopropanol,providing a useful,high-efficient approach for complete mineralizing perfluorinated chemicals.3.The electrochemical technique in two-electrode system(platimum as anode,carbon fiber as working electrode)with ferric chloride as the supporting electrolyte was investigated for removal of perfluorooctanoic acid.Various experimental systems and different radical scavengers were analyzed for removal of PFOA.The system was also monitored by ionic chromatography(IC),ultraviolet spectrophotometry and total organic carbon(TOC)to respectively determine chloride ions concentration,free fluoride concentration,different iron valences and concentration and organic carbon content in solution.The possible electrochemical mechanisms for the removal of PFOA were proposed...