Role of Biochar Supported Nano-Photocatalysts for Removal of Dyes

Dyes are extensively used in textile, leather accessories, paper, paint, printing, furniture, food, and plastic products. Release of untreated dyes causes adverse effects on environment. Different physical and biological treatments are inefficient to treat dyes. In this regard, photocatalysis using nanoparticles has emerged as an efficient method for degradation of the dyes. TiO2, Fe2O3, and ZnO under UV or sunlight exposure are used as nano-photocatalysts. These nano-photocatalysts have potential to convert toxic pollutants into simpler end products such as CO2 and H2O without generation of secondary pollutants. Photocatalytic degradation of dyes is mainly affected by concentration of dye, amount of photocatalyst, intensity of irradiated light, time of irradiation, and effect of dissolved oxygen and pH. Biochar has emerged as an eco-friendly, cost-effective, and multi-functional product prepared from thermo-chemical conversion of different biomass-based wastes. Physico-chemical properties of biochar enable it to support various light-active components with easy isolation and recovery of catalyst. Incorporation of biochar with nano-photocatalyst provides enhanced porosity, specific surface area, number of active sites, chemical stability, charge separation, and photocatalytic efficiency. The present chapter focuses on fundamentals of photocatalytic process, synthesis of biochar supported nano-photocatalysts, their application for removal of dyes, mechanism involved, and future prospects.