Impacts of multi-foulings on salinity gradient energy conversion process in negatively charged conical nanochannels

Membrane fouling inevitably occurs during nanofluidic reverse electrodialysis. Herein, the impact of multi-fouling on the energy conversion performance of negatively charged conical nanochannels under asymmetrical configurations is systematically investigated. The results reveal that in Configuration I, where a high-concentration solution is applied at the tip side, at small concentration ratios, multiple foulings reduce the electric power. In Configuration II, where a low-concentration solution is applied at the tip side, multiple foulings near the base side contribute to the electric power. Any fouling that formed near the low-concentration entrance diminished the electric power and energy conversion efficiency. Multi-fouling lowered the electrical power consumption by 69.27% and 99.94% in Configurations I and II, respectively. In Configuration I, the electric power first increased with increasing fouling surface charge density, reached its maximum value, and thereafter decreased. In Configuration II, the electric power first decreased with increasing fouling surface charge density, reached its minimum value, and thereafter increased. Large negative or positive charge densities of fouling contribute to the electric power and energy conversion efficiency.