Engineering nanocomposite membranes of sodium alginate-graphene oxide for efficient separation of oil-water and antifouling performance

Abstract

The consistent oil spill incidents and industrial wastewater disposal impart an adverse impact on human health and nature. The utilization of porous membranes to address these problems has been predominantly investigated. Recently, hydrophilic membranes, have revealed the promising potential in oil-water separation. Thus, the present work focuses on the fabrication of hydrophilic nanocomposite membranes by incorporating the graphene oxide (GO) nanosheets to develop cost-effective, environmentally friendly and sustainable membranes of sodium alginate (SA) for separating oil/water mixtures. The pristine sodium alginate (pSA) and composite membranes (SA-GO) were developed by solution casting and crosslinking approach. Permeation experiments confirmed that the composite membranes possess porosity, hydrophilicity and high pure water flux (PWF) in comparison to pSA membranes. The structural and morphological features of fabricated membranes were confirmed by X-ray diffractometry (XRD), Fourier transform infrared spectroscopy (FTIR), and Scanning electron microscopy (SEM). Moreover, the thermogravimetric analysis (TGA) and tensile testing results confirmed that the composite membranes have high mechanical endurance and thermal stability over pSA membranes. In addition, the wettability and surface hydrophilicity were further assured by measuring the water contact angle. The nanocomposite membranes significantly outperformed than the pristine SA membranes in the antifouling test without the requirement for alkaline or acidic washing. These membranes were then employed for oil-water separation utilizing a pressure-driven filtration method. The separation efficiency (% S), flux recovery ratio (% FRR) and protein rejection (% R) were also evaluated for the engineered membranes. The results depict that introducing 1.5 wt% GO to the SA matrix improved oil removal efficiency by 93.26%, antifouling performance with a protein rejection rate of 90%, and the flux recovery ratio of > 88%, repeated over the three filtration cycles.