Preparation Of Heavy Metal Ion Chelating Nanofibers And Their Adsorption Performance Evaluation

In recent years, with the rapid development of industry, heavy metal pollution isbecoming more and more serious. Heavy metals can’t be degraded by microorganisms,and have a significant threat to human health and safety through food chain in the end.Therefore, it is of great significance to develop green and efficient treatment technologyfor control and recovery heavy metals from wastes via efficient and recycableadsorption agent.This thesis focused on preparation of ion imprinted nanofibers and imido aceticacid type chelating nanofibers, and inverstigation of their adsorption performance suchas thermodynamics, kinetic，selectivity and regeneration with simulated heavy metalwaste water. The mainly results were given as follows:(1)The PAN nanofibers with diameter of250±30nm were fabricated, when theconditions of solution concentration9~10%, voltage23kV, working distance10cm,and flowing rate0.3mL/h were applied.(2) The crosslinking PAN nanofibers were changed into amidoxime chelatingnanofibers by reacting with hydroxylamine hydrochloride. The optimized conditionswere NH2OH.HCl concentration3g/L, pH6.8, reaction time3h and temperature80℃,we obtained chelateing nanofibers have perfect morphologies and mechanical propertieswith conversion rate of60%.(3) The ion imprinted nanofibers were harvested after the functional nanofibersimmersed in100mL of500mg/L Pb2+aqueous solution at pH5.8for2h, crosslinkedwith glutaraldehyde, washed with0.1mol/L HCl.(4) The adsorption capacity ion imprinted nanofibers for Pb2+was very high, itreached upto580mg/g. The adsorption rate was fast enough and reached the adsorptionequilibrium within15minute. The selectivity coefficients of ion imprinted nanofibersfor Pb2+in mixed metal ions (Pb(II)/Cu(II), Pb(II)/Ni(II) and Pb(II)/Cd(II)) solutionswere47,101and162, respectively. The adsorption model obeys pseudo-second-orderkinetic and Langmuir isotherm model, and adsorption process belongs to anendothermic reaction, sugessted that the adsorption capacity increased whentemperature was elevated. The adsorption capacity of ion imprinted nanofibers wasabout64%of initial adsorption capacity after40adsorption/desorption cycles, revealedthat ion imprinte nanofibers was a promising recyclable adsorbent. (5) Imido acetic acid type chelating nanofibers were prepared by reactioncrosslinking PAN nanofibers with sodium chloroacetate, the adsorption capacity ofnanofibers was significantly higher than that of reported chelating fibers, whichindicated that imido acetic acid type chelating nanofibers was a potential adsorbent withhigh adsorption capacity to be widely application.