Investigation Of Plumbum Ion Adsorption By A Polyvinylidene Fluoride-type Chelating Membrane

A polyvinylidene fluoride(PVDF)-type chelating membrane bearing poly(amino phosphonic acid)and poly(amino carboxylic acid)groups was fabricated and employed for the removal of Pb(Ⅱ)from the solution.The as-prepared chelating membrane was characterized using techniques of scanning electron microscopy(SEM),energy dispersive X-ray spectrometry(EDS),Fourier transform infrared spectroscopy(FTIR),X-ray photoelectron spectroscopy(XPS),and solid-state nuclear magnetic resonance spectroscopy(NMR).The series of Pb(Ⅱ)adsorption by this chelating membrane were studied aiming for the removal of Pb(Ⅱ)from the water bodies.Effects of pH,initial Pb(Ⅱ)concentration,temperature,contact time,three coexisting cations(Cd(Ⅱ),Ni(Ⅱ)and Fe(ⅡI)),as well as three complexing reagents(citrate,nitrilotriacetic acid(NTA)and ethylenediaminetetraacetic acid(EDTA))on the Pb(Ⅱ)adsorption by the membrane were investigated.The adsorption kinetics,adsorption isotherms,and breakthrough curves of the chelating membrane toward Pb(Ⅱ)at the presence of above-mentioned cations and complexing reagents were also studied.In addition,the breakthrough curves of the membrane were measured.At the presence of coexisting cations and complexing reagents,the decrease in Pb(Ⅱ)uptake of the membrane was validated.Negative effects of three cations on the Pb(Ⅱ)uptake followed a sequence of Cd(Ⅱ)>Ni(Ⅱ)>Fe(ⅡI);interferences of three complexing reagents were in the order: ethylenediaminetetraacetic acid>nitrilotriacetic acid>citrate.The Langmuir and the Lagergren second-order models were competent for the descriptions in adsorption isotherms and adsorption kinetics of the Pb(Ⅱ)uptake;the bed depth service time model was suitable for describing obtained breakthrough curves.The Pb(Ⅱ)uptake of the membrane was a spontaneous and exothermic process.This cheating membrane bearing polyamino phosphonic acid and polyamino carboxylic acid groups would be efficient to remove Pb(Ⅱ)from the aqueous solution.The breakthrough curves of the membrane can describe better by Bed Depth Service Time(BDST)model.The dynamic adsorption process demonstrates that with the increase of thickness of the film,the extended trends of tb and te can be observed and with the increase of flow velocity breakthrough time,exhaustion time will be shortened.