Exploring the Benefits of Rice Husk Waste: Synthesis and Characterization of Biochar and Nanobiochar for Agricultural and Environmental Sustainability

Abstract

Rice husk waste is a significant byproduct of rice production in developing countries, with a vast annual production. This waste material has been extensively used as an adsorbent for various substances due to its adsorption capabilities. Biochar, a carbon-rich material produced through pyrolysis of biomass, has gained attention for its diverse applications in agriculture and the environment. In this study, rice husk biochar and nanobiochar were synthesized and characterized to explore their potential benefits for agricultural and environmental sustainability. The biochar was prepared by pyrolysis of rice husk at 500°C in a low-oxygen environment, followed by grinding and sieving. Nanobiochar was obtained by ball milling the biochar particles. The physical and physicochemical properties of both biochar and nanobiochar were evaluated, including bulk density (0.41 and 0.59 Mg m-3), particle density (0.49 and 0.54 Mg m-3), water holding capacity (168.6 and 178.5%), pH (8.4 and 7.3), electrical conductivity (0.31 and 0.45 dS m-1), cation exchange capacity (26.3 and 24.1cmol (p+) kg-1), volatile matter content (21.91 and 18.90%) and particle size distribution. Spectral analysis techniques such as DLS, FTIR, XRD, SEM and EDX were used to examine the size, zeta potential functional groups, crystallinity, porosity and elemental composition of the samples. The results showed that nanobiochar exhibited improved physical characteristics, such as higher porosity and water retention capacity, compared to biochar. The elemental composition and volatile matter content differed between the two materials. Nanobiochar also had significantly smaller particle size (11 nm) and a stable zeta potential. These findings suggest that rice husk nanobiochar has great potential for applications in soil fertility enhancement, adsorption of contaminants and waste management. The study contributes to the understanding of the properties and applications of rice husk waste-derived biochar and nanobiochar, promoting their utilization for sustainable agricultural and environmental practices.