Membrane fouling continues to hamper the performance of membrane-filtration processes. A challenge with macromolecular foulants like proteins is that macroscopic characterizations, like net electrical charge, may be poorly correlated with membrane fouling. This necessitates a molecular-scale analysis of the local interactions. In this study, molecular dynamics simulations have been performed to understand the interactions between two similar-sized proteins with opposite overall charges (namely, lysozyme and α-lactalbumin) and a negative-charged membrane. Surprisingly, the protein–membrane distances and adsorption probabilities of both proteins are similar. Compared with the positive-charged lysozyme, the negative-charged α-lactalbumin exhibits (a) greater protein–membrane attractive interaction energy due to synergy among adsorption sites; (b) lower root-mean-squared deviations (RMSD); and (c) greater number of residues that show low root-mean-squared fluctuations (RMSF). These results indicate that local interactions are critical and thus highlight the pitfall of using the overall protein characteristics as predictors of membrane fouling.
All Science Journal Classification (ASJC) codes
- Environmental Engineering
- Chemical Engineering(all)