Study On The Preparation Of Activated Carbon Loaded Ni/Fe Bimetallic Particles And Treatment Of Hexavalent Chromium In Water Environment

Zero valent iron has attracted so much attention of experts in various pollutants treatment,because of its excellent adsorption and reduction properties.However,the problems such as instability,conglomeration and passivation in the reaction process limit its further popularization and application.In order to enhance the stability,improve the reaction activity and dispersion of metal particles,this study combining the two modification methods,metallic modification and solid load,prepared activated carbon supported Ni/Fe bimetallic particles?Ni/Fe-AC BPs?through electrodeposition,which provide a theories foundation and technical support for the popularization and application of zero valent iron particles in pollution control.First of all,taking the removal efficiency of hexavalent chromium for the assessment indicator,the best material rate of electrolyte was achieved through orthogonal experiment.Based on this,the influence of electrodeposition time,current density and electrodeposition temperature on the preparation of Ni/Fe-AC BPs was studied with control various methods.Secondly,Ni/Fe-AC BPs was characterized by four methods,field emission scanning electron microscopy?FESEM?,energy dispersive spectrometer?EDS?,X ray diffractometer?XRD?and full automatic specific surface area and porosity analyzer?BET?.The characterization results showed that Ni/Fe bimetallic particles were spherical and dispersive,and Ni/Fe-AC BPs had high adsorption properties.Then,in order to explore the engineering adaptability of Ni/Fe-AC BPs,the experimental study on the removal of hexavalent chromium by Ni/Fe-AC BPs under different water environment conditions was carried out.The results were summarized as follows:?1?Under low initial concentration and acid conditions,the removal of six valence chromium is the best.?2?The catalytic reduction of hexavalent chromium by Ni/Fe-AC BPs was adaptable to solution temperature.?3?Coexisting ions in water,Cl^-could promote the reaction by accelerating the corrosion of Fe;SO₄^2-would promote the formation of the surface passivation film on Ni/Fe-AC BPs,which hindered the catalytic reduction reaction.Finally,by comparing the removal effect of six valence chromium with AC,Fe-AC and Ni/Fe-AC BPs,it is proved that metal modification greatly enhanced the reaction activity of zero valent iron.In addition,the regeneration experiment of Ni/Fe-AC BPs achieved good results:after 8 times reused,the removal efficiency of hexavalent chromium still reached 85.96%.In order to study the mechanism of catalytic reduction reaction of Ni/Fe-AC BPs,the research on hexavalent chromium removal kinetics was carried out.In the study of reaction kinetics,it was found that the catalytic reduction reaction of hexavalent valence chromium by Ni/Fe-AC BPs followed the first order reaction.And the apparent activation energy Ea was calculated to be 20.62kJ mol^-1,which proved that the dominant reaction is the chemical adsorption.