Remediation of Cadmium-Contaminated Soil Using Biochar Derived from Wheat Straw, Rice Husk and Bagasse

Abstract

Improper waste disposal has resulted in rapid deterioration of the environment and the advent of fatal diseases. Carcinogenic substances that percolate into the ground deteriorate the quality of groundwater and soil. Moreover, pollution from large-scale burning of agricultural waste each time after the harvest season makes the goal of a healthy environment of utmost importance. Toxins, such as polycyclic aromatic hydrocarbons (PAH) and heavy metal contaminants, have several pathways to enter into the environment and bio-accumulate within living organisms. The objective of this study is to synthesise a substance that will break the source-receptor pathway resulting in cleaner water and soil. Biochar, through ion exchange or physical adsorption, has the capacity to adsorb heavy metal ions such as those of cadmium. The biochar was synthesised from biomass consisting of wheat straw, rice husk and bagasse. The biomass was then heated to temperatures ranging from 300 to 700 °C using the process of slow pyrolysis, in an environment in which the oxygen supply was limited. The samples were then subjected to Fourier transform infrared spectroscopy (FTIR) to ascertain the functional groups present followed by powder X-ray diffraction (XRD) to determine the elements or form of metal oxides present in the samples. The samples were mixed with a known amount of cadmium solution, and the final testing was performed using atomic absorption spectroscopy (AAS). The final testing directly showed the heavy metal ion adsorption efficiencies of biochar derived from different types of biomass, giving an insight into the future scope of using biochar has a remediating agent