Exfoliated Mg-Al-Fe layered double hydroxides/polyether sulfone mixed matrix membranes for adsorption of phosphate and fluoride from aqueous solutions

Mg-Al-Fe layered double hydroxides (LDHs) were exfoliated and incorporated in polyether sulfone membranes for the removal of phosphate and fluoride for the first time. The exfoliation methods, coagulation bath, LDH amount, interfering ions, adsorption isotherm, desorption and reuse of the membranes were investigated. It was found that LDHs could be quickly exfoliated in formamide/N, N-dimethylformamide (DMF) solvent mixtures with sodium carboxymethyl cellulose as a stabilizer. The membranes displayed much higher adsorption capacity for phosphate (5.61 mg/g) and faster adsorption rate than the un-exfoliated materials. With increased DMF content in the coagulation bath, the static and dynamic adsorption capacity rose. Interference from Cl-and SO42-(50 mg/L) on adsorption of phosphates was not apparent. The membranes displayed excellent reusability in dynamic adsorption/desorption. The membranes also showed high adsorption capacity for fluorides (1.61 mg/g). (C) 2017 The Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences. Published by Elsevier B. V.