Modified PVA-co-PE Nanofiber Membrane Used As Heavy Metal Removal

Heavy metal pollutions in the industrial wastewater have become a serious environmental problem in the whole world.It's worthy to remove the heavy metals from water before discharge due to its non-biodegradable and enrichment properties.So it's important to develop a kind of high efficient and recyclable material to remove the heavy metals.The PVA-co-PE nanofiber membrane was prepared using the industrial produced PVA-co-PE nanofiber.In order to improve the content of hydroxyl group which could react with more BTCA,NCC was deposited on the membrane.BTCA was used to functionalized this composite nanofiber membrane,hence membrane possessed carboxyl group was more easily to chelate with heavy metal ions.SEM,ATR,XPS were used to characterize the morphology and structure of the modified membrane.The BTCA modified nanofiber membrane was applied to remove Cr???and Pb???.The adsorption kinetics,isotherm of Pb???and the effect of metal mixture on metal uptake as well as the reuse of BTCA modified nanofiber membrane were studied.Compared to unmodified membrane,BTCA modified membrane had good capability of removing Cr???and Pb???,especially after treated by NaHCO₃.The maximum uptake of untreated modified membrane towards Pb???was 19.23 mg/g and the corresponding removal efficiency was 61.87%,while the NaHCO₃ treated membrane towards Pb???was 52.89 mg/g and 99.20% seperately.The kinetics of adsorption of Pb???on both membranes fitted in pseudo-second order equation,indicating that the metal ions were chemically adsorbed.Results indicated that the untreated membrane fitted in Langmuir isotherm,while the NaHCO₃ treated one fitted in Freundlich isotherm better.Other heavy metals promoted the removal ability of Cu???in the metal mixture.However,the adsorpbility of Cr???and Pb???decreased in case of other metals occupied the bind sites.In addition,NaHCO₃ treated modified membrane kept a better recyclability.As a result,BTCA modified membrane could be used as a low-cost,high-efficiency and recyclable heavy metal adsorbent.In addition,polyrhodanine was immobilized onto the PVA-co-PE membrane via deposition polymerization method.As the same,the polyrhodanine modified nanofiber membrane was applied to remove Hg???and Pb???.The adsorption kinetics and adsorption isotherm towards Hg???as well as the effect of metal mixture on metal uptake and the recycle of polyrhodanine modified nanofiber membrane were also discussed.Polyrhodanine modified membrane had good capability of removing Hg???and Pb???,especially Hg???.The maximum uptake of untreated modified membrane towards Hg???and Pb???were 17.26 mg/g and 3.834 mg/g separately,the corresponding adsorption were 88.51% and 7.473%.The kinetics of adsorption of Hg???on both membranes fitted in the pseudo-second order equation.What's more,the modified membrane fitted in Langmuir isotherm.Polyrhodanine modified membrane could keep the same capability to remove Hg???in the metal mixture compare to the alone metal ions solution.Moreover,Hg???could promote the removal efficency of Pb???in the mixed heavy metal solution.The recyclability of modified membrane was not good enough.However,the polyrhodanine modified membrane had an excellent antibacterial property.