Polyacrylonitrile Fiber with Light-Driven Intelligent Reversible and Switchable Wettability As an Environmental Benign Solid Base for Biodiesel Production

Vigorous advocacy for the promising strategy on biodiesel replacing petrodiesel can effectively alleviate the dual pressure of energy deficiency and environmental pollution. Nevertheless, the difficulty of lowering larger mass transfer resistance between two-phases of alcohol/oil is a stumbling block in the biodiesel production. Furthermore, the high catalytic efficiency of the most commonly used solid bases for biodiesel production is weakened due to the saponification reaction caused by fatty acids in feedstock. Addressing these two issues has emerged as a pressing concern for achieving efficient biodiesel production. Herein, a polyacrylonitrile fiber (PANF) with light-driven intelligent reversible and switchable wettability, i.e., PANF-NH2@RAFT@SPA&[AD][OH] featuring Brønsted-Lewis di-base sites and photoresponsiveness, was successfully fabricated through reversible addition fragmentation chain transfer strategy. Physicochemical properties of the resulting fibers were characterized by FT-IR, XRD, NMR, TGA, SEM, TEM, XPS, WCA, and UV–Vis. The effect of methanol-to-oil molar ratio, reaction temperature, reaction time and catalyst feed on biodiesel production was also investigated. Under optimal conditions, a maximum soybean oil conversion of 100% was achieved with a corresponding biodiesel yield of 98.97%, which is an exceptional and unprecedented result. These impressive results can be ascribed to the microenvironment facilitated by the novel intelligent amphiphilic PANF, which effectively enhances mass transfer in a biphasic medium phase of methanol/oil. The microenvironment could be rapidly changed via Vis-regulating PANF hydrophobicity, followed by observably promoting catalyst recovery and phase separation between resultant biodiesel and excess methanol. This catalyst shows no obvious changes in terms of the catalytic activity and selectivity after successive reuses of up to 10 cycles. The economic feasibility and negligible environmental impact of this methodology, coupled with its expediency and efficacy for conducting experiments at kilogram-scale quantities, render it highly compatible with large-scale industrial production of biodiesel.