Preparation Of Polypyrrole Doped Graphene Aerogel And The Application Of Synergistic Removal Of Cr(?) And Bisphenol A

With the continuous complexity of wastewater components,treatment of multicomponent wastewater had been extensively researched.Thereinto,removal of the coexisting heavy metals and organic matters attracted much more attention.In particular,with improper treatment,yielding water containing abundant pollutants might inflow into surface water or seeped into groundwater,which posed serious threats to human life and drinking water sources.For instance,hexavalent chromium(Cr(?)),as priority pollutant,could cause skin rashes,liver damage,malformation,and weaken immune systems,even lung cancer and death.The common endocrine disrupting compounds(EDCs)with embryo toxicity and teratogenicity,such as bisphenol A(BPA),had been found in plastic baby bottles and even water supplies,which could increase the occurrence of leukemia and other cancers.As we all know,the traditional treatment methods of wastewater,including physical,chemical,physicochemical,biological methods,normally intended for removing one component wastewater.Thus,the development of new technologies for the removal of mixed pollutants was of great importance.It would be significant if the simultaneous reduction of heavy metals and oxidization of organic pollutants could be achieved by feasible methods.In this paper,synthesis of polypyrrole/reduced graphene oxide aerogel(PGAs)as particle electrodes and their application in three-dimensional electrode system for simultaneous reduction of hexavalent chromium(Cr(?))and oxidation of bisphenol A(BPA)were implemented firstly.The physical and chemical performances of PGAs were characterized by adsorption experiments and the characterization techniques,such as SEM,XRD,XPS,Raman and BET.Electro-catalytic properties were investigated systemically in terms of the influences of pivotal factors,such as pH,the concentration ratio of Cr(?)and BPA,voltage and the ratio of PGAs mass to solution volume(S/L).The results showed superb removal rates of 98.52 ± 1.48%for Cr(?)and 98.00 ± 1.17%for BPA within 30 min under the optimal conditions(pH=3,the concentration of Cr(?)and BPA are 80 mg/L and 20 mg/L,voltage is 25 V and the ratio of PGAs mass to solution volume is 1 mg/mL).Furthermore,synergy of both pollutants was testified by the comparison of removal rates in electro-catalytic kinetics and their fitting in mixed solution with kobs-cr(?)= 0.2019 min-1,kobs-BPA = 0.1463 min-1 significantly higher than that in one-component aqueous solution(kobs-cr(?)= 0.0397 min-1,kobs-BPA = 0.0417 min-1).After 20 cycles of experiments,there were still high contaminants and total organic carbon(TOC)removal rates,which showed excellent reutilized ability of PGAs.More deeply,final destination of Cr(?)was analyzed by X-ray photoelectron spectroscopy(XPS)and scanning electron microscope-energy dispersive X-ray spectroscopy(SEM-EDX).Meanwhile,intermediates of BPA oxidized with the aid of Cr(?)and ·OH were analyzed and a possible degradation pathway was proposed.Importantly,Cr(?)/BPA system provided a remarkable example of a "waste control by waste"strategy for the synergetic removal.