Cation-π interaction in Mg(OH)2@GO-coated activated carbon fiber cloth for rapid removal and recovery of divalent metal cations by flow-through adsorption

Sorption is considered a promising approach for removing various divalent metal cations, yet the complicated recovery and regeneration strategy restricts the application of powder-like adsorbents. Herein, we report an innovative Mg(OH)2@GO adsorbents loaded on activated carbon fiber cloth (ACFC) using an electrophoretic deposition process (EDP) of Mg(OH)2 and graphene oxide (GO) suspensions to achieve rapid removal of Cd2+, Pb2+, Ni2+, and Cu2+ via flow-through adsorption over an ultra-short period time. FESEM and HRTEM results revealed a cross-linked structure on the ACFC surface derived from the cation-π interaction between Mg2+ and GO under EDP. Importantly, by virtue of oxygen-containing functional groups and π electron region, Mg(OH)2@GO exhibited high adsorption capacities for Pb2+, Cu2+, Cd2+, and Ni2+, which could reach 647.2, 439.5, 297.3, and 219.1 mg g−1 at 293 K, respectively. Furthermore, Mg(OH)2@GO-ACFC possessed a rapid regeneration capability with EDTA by a flow-through system for divalent metal cations desorption and exhibited excellent repeatability in 5-cycle tests. Overall, we propose the novel flow-through system that facilitates the rapid adsorption and recovery of divalent metal cations for wastewater treatment.