Adsorptive Removal of Humic Acid by Zirconia Embedded in a Poly(ether sulfone) Membrane

Abstract

The presence of humic acid (HA) in groundwater threatens aquatic life and human health; for the effective treatment of such pollutants, an advanced/hybrid method is essential. In this work, zirconia embedded in poly(ether sulfone) (ZrePES) mixed matrix membranes (MMMs) has been studied for the removal of HA. Chemical precipitation method was utilized to prepare nano zirconia (ZrO2). The modified PES membrane with nano ZrO2 of 2.5 and 5 wt % were studied. Contact angle measurement and protein rejection studies showed an enhanced hydrophilicity with increase in pore radius for ZrePES membranes. Also, the addition of nano ZrO2 altered the membrane morphology and improved pure water permeability. Batch adsorption experiments revealed that HA adsorption efficiency was higher at pH 2 for ZrePES membranes. The HA uptake capacity of 50.5 mg/g was observed for the 5 wt % ZrePES membrane. Experimental adsorption results showed good agreement with adsorption kinetics model. Ultrafiltration studies showed HA rejection was up to 97% for 5 wt % ZrePES membrane. The effects of natural substances and their impact on HA rejection in ZrePES membrane were also analyzed and discussed.