Conductive and self-cleaning composite membranes from corn husk nanofiber embedded with inorganic fillers (TiO₂, CaO, and eggshell) by sol–gel and casting processes for smart membrane applications

Abstract

The utilization of corn husk as a renewable bio-cellulose material for producing bio-composite membranes through wet chemical and sol–gel process offers numerous advantages. It is an abundant, inexpensive, nontoxic, and readily available agricultural waste product. To enhance the properties of bio-composite membranes, various particulate ionic fillers such as titanium dioxide, calcium oxide, and eggshell (as a source of calcium carbonate) are incorporated in different weight percentages (0, 1, and 5%). These fillers act as additives to the corn husk nanofiber mixed with polyvinyl alcohol during the formation of the biomembrane. The resulting biocomposite membranes exhibit several desirable characteristics. They are lightweight, easy to shape, biodegradable, nontoxic, and possess excellent physical, mechanical, thermal, and electrical properties. Moreover, the addition of 5 wt% of eggshell powder leads to an increase in the dielectric constant and electrical conductivity, reaching approximately 3.300 ± 0.508 and 1.986 × 103 (Ω·m)−1, respectively. These measurements were taken at a frequency of 500 Hz and a temperature of 27°C. Furthermore, these membranes demonstrate self-cleaning abilities due to a contact angle greater than 90°. The electrical properties of the biocomposite membrane improve with a higher percentage of inorganic filler, making them suitable for applications in smart membranes, as well as mechanical, electrical, and thermal systems.