Single-Layered α-ZrP Nanosheet-Intercalated Graphene Oxide Membrane for Efficient Heavy-Metal-Organic Complex Removal

Heavy metals are present in the form of organic complexes in some industrial effluents, the stable structures of which enable them to be difficultly removed using traditional methods. Recently, graphene oxide (GO) membranes have attracted increasing attention in wastewater treatment; however, it remains challenging for GO membranes to efficiently remove heavy-metal-organic complexes due to their sub-1 nm sizes. Herein, a novel strategy is present to significantly enhance ion removal of GO membranes through the intercalation of as prepared single-layered alpha-zirconium phosphate (alpha-ZrP) nano sheets. The X-ray diffraction and surface zeta potential measurements demonstrate that alpha-ZrP intercalation could decrease the wet interlayer distance (from -13.1 to -12.5 angstrom of 30 wt % alpha-ZrP added) of GO membranes and simultaneously enhance the surface zeta potential (from -35.4 +/- 0.4 to -37.6 +/- 0.9 mV at pH = 7). Using size exclusion and electrostatic repulsion, the obtained GO membranes could efficiently remove various heavy-metal complexes (e.g., > 98.1% rejection toward Cu-EDTA(2-) and -5.8 L m(-2) h(-1) permeating flux) over a wide pH range (2-10), even at very low ion concentrations (e.g., 0.5 mg L-1). This single-layered alpha-ZrP nanosheet intercalation strategy for GO membranes opens new opportunities for the efficient removal of heavy-metal-organic complexes in wastewater.

Automated summary

A novel method using intercalated α-zirconium phosphate nano sheets has been proposed to enhance the removal of heavy-metal-organic complexes by graphene oxide membranes. The intercalation process effectively changes the membrane structure and surface potential, resulting in efficient removal of heavy-metal complexes.