Associate 1999-00

Mark M. Clark

Civil & Environmental Engineering

Charge, Hydrophobicity, and Fouling of Porous Ultrafiltration Membranes

Synthetic polymeric membranes are a relatively new technology which can be used to filter drinking water supplies and remove pathogenic organisms like bacteria, viruses, giardia, and cryptosporidium, as well as troublesome contaminants like nitrates and pesticides. Although membranes have a bright future in the US and elsewhere, membrane efficiency is often severely limited because of membrane fouling, which is the accumulation of materials like natural colloids and organic compounds on the membrane surface. Professor Clark’s research group focuses on identifying and testing new membrane polymers, characterizing polymeric membrane surfaces, and understanding fouling of membranes by colloids and natural organic compounds like humic acids, which are moderate molecular weight polyelectrolytes.

Although advanced microscopic, spectrometry, and surface science tools have been applied to understand the fouling problem on a fundamental level, a question still remains on how natural organic compounds attach to and foul membrane surfaces. One school of thought contends that the wetability of the membrane controls adsorption. During his Center appointment, he plans to modify a technique called Atomic Force Microcopy to understand small scale variations in the wetability and adsorptive fouling of membranes. He also plans to develop a colloidal membrane surrogate, which can be used to quantify membrane charge, as well as the interaction of membranes with charge-determining ions and molecules.