Adsorption Of Ni(?)from The Heavy Wastewater By Functional Polyethersulfone Membrane

The electroplating industry is list as one of the three major polluting industries in the world.The effictive disposal of electroplating wastewater which generated in processing and production has become an important issue in the field of water pollution treatment,and has attracted extensive attantion from scholars at home and abroad.With the point of electroplating nickel rinsing wastewater,the adsorption performance of NTA-TEPA-PES membrane prepared in this study has been studied on the capture of Ni2+from aqueous solution.In this study,the polyethersulfone(PES)-type chelating membrane bearing nitrilotriacetic acid(NTA)and tetraethylene pentamine(TEPA)groups was fabricated by means of low temperature plasma irradiation(LTPI),chemical graft polymerization and solution phase inversion techniques.The morphology,functional groups and chemical compositions of this membrane were characterized by scanning electron microscopy(SEM),energy spectrum analysis(EDS),Fourier transform infrared spectrum(FTIR)and X-ray photoelectron spectroscopy(XPS),also,the batch adsorption and continuous filtration experiments were carried out to evaluate the capture efficiency of fabricated membrane toward Ni2+.The density functional theory(DFT)was used to simulate the design of the NTA-TEPA-PES chelating membrane structure,the feasibility of nickel ion adsorption,and the transition state process of its adsorption of Ni2+.Furthermore,the mechanism of adsorption of Ni2+by NTA-TEPA-PES chelating membrane was analyzed at the molecular level.The results show that the optimal conditions of NTA-TEPA-PES chelating membrane preparation are as fallows:6 g of PES powder,LTPI time is 2 min,the mass ratio of NTA and TEPA is 1:2,and the reaction tempretion between them is 130?.The prepared NTA-TEPA-PES chelating membrane has preferable hydrophilic properties,and the pure water flux is 334.6 L/(m2 h).The adsorption capacity of NTA-TEPA-PES chelating membrane towards Ni2+is 0.57 mmol/g at pH=5.5,initial concentration of Ni2+is 1 mmol/L,and temperature is 298 K.The experimental data were well fitted by PSO adsorption kinetic and Langmuir isotherm adsorption equations model,respectively.The thermodynamic parameters(?G<0??H<0??S>0)demonstrate that the Ni(II)adsorption is a spontaneous,exothermic and entropy-increasing process.the disturbents play a negitive effection in Ni2+adsorption,and metal ions follow the order of Cu2+>Zn2+>Mg2+,while organic complex in descending order:CA>TA>SP.The results of continuous adsorption experiments demonstrate that the breakthrough time prolonged with the increasing membrane thickness,decreasing inflow flux rate and Ni2+initial concentration,and the breakthrough curves were analyzed using the Thomas model.The stable structure for the adsorption of Ni2+by the NTA-TEPA-PES membrane was calculated by DFT,i.e the structure of Ni2+cooperated with O55,O57,N35,N38,N41,and N50.The adsorption mechanism of Ni2+by NTA-TEPA-PES membrane was determined by transition state calculation.