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Lignocellulose nanofibrils (LCN) and cellulose nanofibrils (CNF) are popular nanometer additives to improve mechanical properties and hydrophilic abilities; moreover, lignocellulose has potential as a natural adhesion promoter in fiber-reinforced composites. LCN and CNF were blended into polysulfone (PSF) to prepare ultrafiltration membranes via the phase inversion method. These additives were characterized by Fourier transform infrared spectroscopy and transmission electron microscopy, and the rheological properties such as shear viscosity and non-Newtonian fluid index of the casting solutions were analyzed using a rotational rheometer. The performance of ultrafiltration membranes was characterized using Fourier transform infrared spectroscopy, thermogravimetric analysis and scanning electron microscopy. The pure water flux, bovine serum albumin retention ratio, water contact angle, surface energy, molecular weight cut-off, pore size and mechanical properties were measured. The equilibrium contact angle of water decreased from 63.5 • on the PSF membrane to 42.1 • on the CNF/PSF membrane and then decreased to 33.9 • on the LCN/PSF membrane when the nanometer additives content was 0.8 wt %. The results reveal that LCN and CNF were successfully combined with PSF. Moreover, the combination of LCN/PSF ultrafiltration membranes was more promising than that of CNF/PSF ultrafiltration membranes.

Based on the Onsager reciprocal relation in the linear response regime, we first clarify the equivalence of thermodynamic and electric circuit analyses for electrokinetic energy conversion. Then we present a streaming-potential-based nanofluidic energy conversion system which comprises two immiscible fluids that form a flat interface in a slit-like channel. The validity of the Onsager reciprocal relation to such a two-fluid system is verified. The performance of such an energy converter is illustrated by considering two concrete oil–water systems with different properties. In both cases, we predict that the binary system with a thin oil layer increases both the maximum output power and the energy conversion efficiency, and this enhancement depends strongly on the mobile charges present at the oil–water interface, the salt concentration and the interface location. Concretely, for negatively charged interfaces, we find that the optimal efficiency increases with the interfacial charge for relatively thin oil layers; while for relatively thick oil layers, the interfacial charge has the opposite effect (i.e. reduction effect) on the energy conversion efficiency in the ranges of the parameters. We further investigate these systems from the viewpoint of energy transfer by deriving the related energy equation. We find that viscous dissipation consumes most of the power (more than 90 %), in both single-phase and two-fluid flows. However, the ratio of the viscous dissipation to the power input decreases with increase of the interfacial charge density for the case of a relatively thin oil layer in two-fluid flows. Meanwhile, although the presence of interfacial charges can lead to an increase in electrical dissipation, the amount of the increased power consumption is less than that of the reduced viscous dissipation in the case of a thin oil layer. Therefore, for two-fluid energy converters, the total power consumption can be reduced and the efficiency is improved.

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Ternary blend membranes were prepared with polysulfone (PSf), sulfonated polysulfone (SPSf), and cellulose nanofibers (CNF) by a LoebSourirajan (L-S) phase inversion process. The cross-section and bottom surface morphology of the membranes were analyzed by scanning electron microscopy (SEM), and the performance of the membranes was evaluated in terms of pure water flux, bovine serum albumin (BSA) rejection, contact angle, tensile strength, and breaking elongation. The morphology of the cellulose nanofibers (CNF) was detected by transmission electron microscopy (TEM). Results showed that within a certain range, the addition of SPSf improved compatibility between PSf and CNF, and the addition of CNF could improve the hydrophilicity of the membranes. The maximum value of pure water flux reached 137.6 L/m 2 h, and the minimum value of BSA rejection reached 95.8% when CNF content was 0.3 wt% in casting solution. Also, a certain addition of CNF could enhance the mechanical properties of the membranes.