Synthesis of multi-functionalized Fe₃O₄-NH₂-SH nanofiber based on chitosan for single and simultaneous adsorption of...

A multi-functionalized poly ether sulfone (PES)/ chitosan (CS)/Fe₃O₄-NH₂-SH nanofiber was applied for single and simultaneous removal of Pb(II) and Ni(II) ions from water systems. The structure of nanofibers was evaluated using FTIR, FESEM, BET, BJH, TGA, EDX and XPS analyses. The characterization results showed that the structure of nanofibers was well maintained after adsorption process. The simultaneous effects of solution pH, adsorbent dosage and Fe₃O₄-NH₂-SH content were studied using response surface methodology (RSM). The predicted optimum conditions were identified for both Pb(II) and Ni(II) ions. Furthermore, the influence of contact time, initial ion concentration and temperature were investigated to evaluate the adsorption kinetics, isotherms and thermodynamics, respectively. Kinetic data fitted well to the double-exponential model for both Pb(II) and Ni(II) ions. Also, the results of isotherm investigation showed that a monolayer adsorption onto the PES/CS/Fe₃O₄-NH₂-SH nanofiber was dominant. The maximum adsorption capacity of CS/PES/Fe₃O₄-NH₂-SH was 282.4 mg/g for Pb(II) ions and 95.3 mg/g for Ni(II) ions. The regeneration test of nanofiber adsorbent displayed that the adsorption capacity did not changed significantly after 4 desorption steps. In binary system, the adsorption capacity decreased with the increase of competitive ion concentration. The selectivity of different metal ions followed the order of Pb(II) > Cu(II) > Ni(II) > Co(II) > Zn(II).