Hydrophilic/underwater oleophobic composite hydrogel for efficient oil/water separation in environmental remediation

Abstract The increasing frequency of petroleum oil spill has heightened the need for efficient oil/water separation technologies. This study presents the development of a carboxymethyl cellulose-poly(vinyl alcohol) (CMC-PVA) composite hydrogel for efficient oil/water remediation. The CMC-PVA hydrogel was synthesized via chemical cross-linking (3% v/v glutaraldehyde), and the effects of varying CMC concentrations (2% w/v, 3% w/v, and 4% w/v) were investigated while maintaining a constant PVA concentration of 5% w/v. The hydrogels exhibited excellent underwater oleophobicity and hydrophilicity, enabling gravity-driven oil–water separation. Notably, the CMC-PVA hydrogel with 3% w/v CMC (CMC-PVA-3) achieved a high underwater oil contact angle (>134°) and a low water contact angle (27.1°)resulting in an oil rejection rate of 97%. Permeate flux measurements confirmed its stability, with a maximum flux of 290 LMH over multiple cycles. The remarkable wetting properties and separation performance of the CMC-PVA hydrogel underscore its potential as an effective solution for oil/water remediation. This study introduces a novel composite hydrogel formulation that enhances oil/water separation efficiency while maintaining excellent stability and sustainability for environmental applications.