Surface modification of nanofiltration membrane with kappa-carrageenan/graphene oxide for leachate wastewater treatment

Abstract

In this study, the top layer of commercial UA-60 loose nanofiltration (NF) membranes is coated with cross-linked kappa-carrageenan (κ-CGN) and graphene oxide (GO) solution. Various GO concentrations are investigated to improve salt rejection and antifouling properties. The surface functional groups, surface morphology, elemental analysis, hydrophilicity, and surface charge of all membranes were investigated using a range of analytical tools. Coated membranes are tested for 2000 ppm NaCl (sodium chloride) and MgSO4 (magnesium sulfate) for salt rejection studies. Landfill leachate wastewater was used for antifouling studies. The κ-CGN-GO coating increased the wettability and negative surface charge, increasing salt rejection. The GO concentration of (0.075; wt/v %) with 1.2 wt% κ-CGN aqueous solution is optimal for coating solution. The optimal UA-60-κ-CGN-GO3 membrane showed the highest FRR (flux recovery ratio) of 95.73% and the lowest total fouling percentage of 18.9%, with a slightly low water flux compared to the pristine UA-60 membrane. The κ-CGN-GO coating has the potential to overcome membrane fouling and low selectivity for wastewater treatment owing to the increased selectivity and antifouling properties of the coated membranes.