Effect of clay nanoparticles on the structure and performance of polyethersulfone ultrafiltration membranes

In this work, the effect of clay nanoparticles as a casting solution additive on the morphology and performance of polyethersulfone ultrafiltration membranes was evaluated. Ultrapure water permeability was used to initially survey membrane performance and the membranes cast with 1% clay +1% sodium hexametaphosphate (SHMP) and 2% clay had the highest permeabilities. The pure water permeability had no correlation to membrane thickness, porosity, contact angle, or negative surface charge density. Scanning electron microscopy (SEM) images of the membrane surface and cross-section were used to determine the membrane surface porosity, surface pore size, and internal structure, and all of these membrane features were affected by the clay addition and concentration. The increased permeability of the 2% clay membrane is attributed to its greater surface pore size and porosity. The 1% clay + 1% SHMP, 2% clay, and control membrane were subject to further cross-flow permeability, retention, and fouling evaluations using ultrapure water, sodium alginate solution, and natural surface water. The membranes cast with clay additions had a greater potential for fouling as compared to the control. A simple detergent cleaning procedure indicated the membrane fouling was completely reversible. Membrane structure as a predictor for drinking water treatment performance is discussed. (C) 2013 Elsevier B.V. All rights reserved.