Mixed-charged polyamide-4-sulfocalix [4] arene hollow fiber nanofiltration membranes for heavy metal removal under various pH

Abstract

The presence of heavy metal ions in water sources poses significant risks to both human health and environments; hence, it is critical to develop effective and trustworthy removal techniques. This research aims to fabricate a novel hollow fiber membrane consisting of mixed-charged characteristics via the formation of a positively charged thin film composite (TFC), followed by the infiltration of 4-sulfocalix [4] arene (SCA4). The formation, architecture and separation performance of the mixed-charged nanofiltration (NF) membrane have been confirmed by various characterizations. The SCA4-0.03 NF hollow fiber membrane shows excellent rejection performance up to 99.2% for a variety of ion removals such as common arsenate, nickel (II), and lead (II) ions over a broad pH range. Additionally, the mixed-charged membrane exhibits higher performance stability over 48 h and fouling resistance in both basic and acidic conditions. Consequently, the mixed-charged membrane described in this work is promising to treat both cationic and anionic liquids, and eliminate a variety of ecologically harmful ion species in industries.