Efficient removal of antimony from aqueous solution by sustainable polymer assisted ultrafiltration process

Abstract To minimize the health risks from antimony in aqueous environment, a polymer assisted ultrafiltration (PAUF) process with polyethersulfone (PES) membrane was employed to remove antimony for the first time. Effects of polymer, pH value and functional groups/Sb ions quantity ratio on antimony removal were systematically explored. Finally, antimony rejection efficiencies of 85.8±0.9%-94.7±1.9% were obtained with gradually reduced normalized water permeate flux from 1 to 0.61±0.02 in 120 min PAUF process under the optimal conditions of polyethyleneimine (PEI), pH=3 and functional groups/Sb ions quantity ratio=8. Relevant mechanism investigations indicated that the macromolecule PEI-Sb complexes were formed mainly due to electrostatic interaction during complexation, and then were rejected in ultrafiltration by pore sieving. Meanwhile, ionic strength experiments indicated that the addition of NaCl resulted in significant decline (4.0±0.8%-49.2±3.2%) in antimony rejection efficiencies due to electric double-layer compressing and competition complexation. Moreover, membrane cleaning of 0.2% NaClO and PEI regeneration under pH value of 8 were performed to achieve sustainable cyclic PAUF with reused membrane and polymer. Simultaneously, antimony also could be recovered for reuse during the regeneration of PEI. Results of steady antimony rejection and water permeation demonstrated that this process is a viable alternative for sustainable antimony removal from aqueous environment.