Maximizing Blue Energy via Densely Grafted Soft Layers\nin Nanopores

We\ninvestigate energy generation from salinity gradients inside\na nanopore that is connected to reservoirs at both ends. We consider\nthat the inner wall surfaces are grafted with a densely grafted polyelectrolyte\nlayer (PEL). We developed the PEL grafting density-dependent correlation\nof dielectric permittivity, molecular diffusivity, and dynamic viscosity\nin this endeavor. Using these correlations, we employ the finite element\nframework to solve the equations describing the ionic and fluidic\ntransport. We use a partially hydrolyzed polyacrylamide polymer solution,\nwhich exhibits a shear-thinning fluid, in combination with the KCl\nelectrolyte for energy-harvesting analysis. To describe the shear-rate-dependent\napparent viscosity of non-Newtonian liquid, we have employed the Carreau\nmodel. For a window of right-side reservoir concentration, we investigate\nthe effects of ion-partitioning in conjugation with the change in\nPEL grafting density on the ionic field, ionic selectivity, pore current,\nosmotic power, energy conversion efficiency, and flow field. The findings\nof this endeavor demonstrate how the ion-partitioning effect lowers\nthe screening effect and raises the electrical double layer (EDL)\npotential by reducing the counterions in PEL. We show that the unique\ndistribution of the ionic field leads to a higher prediction of generated\nosmotic power and power density due to the ion-parting effect. Additionally,\nwe establish that the augmentation in PEL space charge density leads\nto improvement in average flow velocity, osmotic power, and consequently\nenergy conversion efficiency. We establish that the generated osmotic\npower density and the energy conversion efficiency become very high\nat the higher grafting density. In summary, inferences of this analysis\nare deemed pertinent in designing the nanoscale device intended for\nhigh and efficient osmotic energy generation.