Tripling the reverse electrodialysis power generation in conical nanochannels utilizing soft surfaces

We theoretically investigate the feasibility of enhancing the reverse electrodialysis power generation in nanochannels by covering the surface with a polyelectrolyte layer (PEL). Along these lines, two conical nanochannels are considered that differ in the extent of the covering. Each nanochannel connects two large reservoirs filled with KCl electrolytes of different ionic concentrations. Considering the Poisson-Nernst-Planck and Navier-Brinkman equations, finite-element-based numerical simulations are performed under a steady-state. The influences of the PEL properties and the salinity gradient on the reverse electrodialysis characteristics are examined in detail via a thorough parametric study. It is shown that the maximum power generated is an increasing function of the charge density and the thickness of the PEL. This means that the maximum power generated may be theoretically increased to any desired degree by covering the nanochannel surface with a sufficiently dense and thick PEL. Considering a typical PEL with a charge density of 100 mol m(-3) and a thickness of 8 nm along with a high-to-low concentration ratio of 1000, we demonstrate that it is possible to extract a power density of 51.5 W m(-2), which is nearly three times the maximum achievable value employing bare conical nanochannels at the same salinity gradient.

Automated summary

Theoretical investigation on enhancing reverse electrodialysis power generation by covering nanochannel surface with a polyelectrolyte layer (PEL) shows that increasing the charge density and thickness of PEL can result in higher power generation. This study demonstrates that by using a typical PEL with specific properties, it is possible to achieve nearly three times the maximum power density compared to bare conical nanochannels at the same salinity gradient.