Synthesis and exploration of physical properties of nanobiochar synthesized from rice straw for its applications in arsenic remediation from contaminated water environments

Abstract

Arsenic (As) is a widespread carcinogenic element that emerges due to geogenic and anthropogenic processes and poses detrimental effects on public health. Biochar is a carbonaceous, renewable, and sustainable material synthesized under low or absent oxygen. Thus, the present study explores the application of biochar obtained via pyrolysis at 500 °C for 2 hrs, followed by ball milling for 3 hrs at 500 rpm to obtain nanobiochar materials for As removal from contaminated environments. Characterization of biochar has been performed for physico-chemical analysis. Different functional groups, including hydroxyl, carboxyl, and alkene, are observable using Fourier Transform Infrared Spectroscopy, contributing to As removal from water. Scanning Electron Microscope analysis shows the porous nature of nanobiochar, which also contributes to remediation. Transmission electron microscope analysis shows an average particle size of nearly 28.12 nm. The As(V) removal efficiency was obtained with an adsorption capacity of 55.1 µg/g at pH 8 to mimic natural water conditions for 6 hrs of biochar-arsenic interactions. The possible adsorption mechanisms of As species on biochar surfaces are electrostatic attractive forces, surface chemical bonding, ion exchange, and precipitation. Future research must concentrate on applications of low-cost, renewable, and carbon material, i.e., biochar for decontaminating natural groundwater samples containing various emerging contaminants for safe and clean drinking water.