Fabrication Of Chitosan Composite Materials For Heavy Metal Ions Adsorption

Pb(?)and AS(?)are two heavy metal ions that seriously threaten the health of human and could cause irreversible damage to the human body.Therefore,the removal of Pb(?)and AS(V)in water bodies and foods is particularly important.Chitosan a natural biopolymer having good biocompatibility and rich amino groups on its surface that can chelate heavy metal ions,but chitosan has the disadvantages of easy dissolution under acidic conditions and difficulty in solid liquid separation.In this paper,chitosan is modified to improve its stability in solution and the properties of adsorbing heavy metal ions.1.Metal organic frame material(MIL-125)/chitosan gel beads were synthesized for the adsorption of Pb(?)from aqueous solutions.The surface composition and functional groups of gel beads were characterized by scanning electron microscope,Fourier transform infrared spectroscopy,X-ray photoelectron spectroscopy and thermogravimetricanalysis.The effects of initial Pb(?)concentration,pH,adsorption time and temperature on the adsorption process were studied.Notably,it was found that the adsorption of Pb(?)onto the MIL-125@CS beads reached equilibrium in 180 min to a level of 407.50 mg/g at 25?.In addition,kinetic and equilibrium experiments provided data that were fit to the Langmuir isotherm model and pseudo-second-order kinetics.Furthermore,reusability tests showed that MIL-125@CS retained 85%of its Pb(?)-removal capacity after five reuse cycles.2.Based on chitosan,magnetic attapulgite modified with ATPS and embedded in CS gel beads for lead ion removal.The materials were characterized by Fourier transform infrared spectrum,thermal weight analysis,scanning electron microscope,and X-ray diffraction.The properties of Pb(?)in the water adsorbed by the gel beads were investigated.The effects of initial Pb(?)concentration,pH of solution,adsorption temperature and adsorption time on the adsorption process were studied experimentally.Notably,it was found that the adsorption of Pb(?)onto the APTS-g-MAPT@CS beads reached equilibrium in 90 min to a level of 625.34 mg/g at 25?.In addition,kinetic and equilibrium experiments provided data that were fit to the Langmuir isotherm model and pseudo-second-order kinetics.Furthermore,reusability tests showed that APTS-g-MAPT@CS retained 84%of its Pb(?)-removal capacity after five reuse cycles.3.The gel beads made from magnetic chitosan and nanometer zinc oxide mixed with sodium alginate were studied.The adsorption properties of AS(V)were investigated,the impact of initial concentration,pH,adsorption temperature and removal time on adsorption As(V)were discussed.Notably,it was found that the adsorption of As(V)onto the MCS/ZnO@Alg beads reached equilibrium in 90 min to a level of 67.50 mg/g at 25?.In addition,kinetic and equilibrium experiments provided data that were fit to the Langmuir isotherm model and pseudo-second-order kinetics.Furthermore,reusability tests showed that MCS/ZnO@Alg retained 85%of its As(V)-removal capacity after five reuse cycles.