Difunctional hierarchical porous SiOC composites from silicone resin and rice husk for efficient adsorption and as a catalyst support

Abstract

Porous SiOC composites were prepared by varying the proportions of silicone resin and rice husk at different pyrolysis temperatures using biotemplate method. The as-prepared composites were investigated by various analytical techniques and utilized for adsorption of ciprofloxacin from wastewater and as a catalyst support. The composites consist of the SiOC matrix, silicon dioxide and free carbon. The optimized composite has the hierarchical pores with high specific surface area of 767.61 m2/g and pore volume of 0.84 cm3/g. The adsorption process of ciprofloxacin onto SiOC composites adheres to the pseudo-second-order kinetic model. The external film diffusion and intra-particle diffusion jointly control the adsorption rate, and the Langmuir and Freundlich models can properly describe the adsorption isotherms. The SiOC samples show a large adsorption capacity (148.0 mg/g) and superior reusability, suggesting its exceptional reusability and potential application in antibiotic-containing wastewater treatment. Furthermore, the photodegradation rate constant of the SiOC/g-C3N4 composite is almost 2.28 times as high as that of pristine g-C3N4, indicating that the SiOC composites can be employed in a favorable catalyst support ascribed to the enhancement of photodegradation performance after loading photocatalyst on the SiOC adsorbent.