Efficient removal of As(III) by Cu nanoparticles intercalated in carbon nanotube membranes for drinking water treatment

摘要

Arsenic contamination is threatening drinking water safety in many areas around the world. Among different arsenic species in water, arsenite or As(III) is the most difficult one to remove due to its neutrality in drinking water. Therefore, development of novel materials is warranted for efficient As(III) removal. Herein, novel nanocomposite materials were facilely prepared by intercalating Cu nanoparticles into carboxylated/hydroxylated carbon nanotubes (CNT) deposited on top of a conventional polymeric membrane. The as-prepared membrane possessed high pure water permeability (4639-4854 Lm(-2) h(-1) bar(-1)) and capability to remove more than 90% of As(III) at transmembrane pressures below 0.01 bar, which is plausible for gravity-driven membrane (GDM) filtration applications. Compared to Fe-based materials reported in the literature, the Cu/CNT nanocomposite membranes exhibited robustness in removing As(III) at a pH range of 5-9 and in the presence of chloride, nitrate, bicarbonate, sulfate and natural organic matter. A mechanical investigation suggests that the filtration process involves direct adsorption of As(III) onto Cu/CNT composites. As(V) species were also produced due to oxidation of As(III) by dissolved oxygen under the catalysis of Cu and adsorbed by Cu/CNT composites. Overall, the novel Cu/CNT nanocomposite membranes exhibit promising potentials in As(III) removal from contaminated water, and are worth of further investigation for their suitability in drinking water treatment.