Effective mitigation of Cadmium contamination in soil through Sawdust Biochar application

Abstract

Cadmium (Cd) contamination in soil is a serious environmental concern, and this study examines the effectiveness of sawdust biochar in reducing Cd contamination over three months. The study explores different sawdust biochar application rates and their effects on the amount of extractable Cd in the soil. According to the study, sawdust biochar has a high potential for addressing Cd pollution. Importantly, over the duration of the investigation, extractable Cd concentrations gradually decreased as a result of the use of biochar. In particular, compared to lesser application rates of 2.5% and 1.25%, the highest biochar application rate (5%) resulted in a significant reduction in cumulative leachable Cd content. Additionally, compared to the control group, all biochar-amended soils showed considerably decreased cumulative leachable Cd levels. The leachate study demonstrated the time-dependent efficiency of biochar in lowering Cd concentrations, with Cd concentration declining from 14 mg/L in August 2023 to a meager 0.004 mg/L in October 2023. Diffusion within the porous structure of biochar was determined to be the main process underlying heavy metal adsorption. However, the observed decrease in the effectiveness of heavy metal removal with biochar may be explained by surface oxidation, which creates a greater number of accessible adsorption sites. Furthermore, the soil's capacity to absorb Cd2+ was greatly improved by the raised pH brought on by biochar application, further enhancing Cd removal. The study also showed the importance of pyrolysis temperature on biochar characteristics, with higher temperatures greatly improving Cd adsorption capability. This study's findings highlighted the significant potential of sawdust biochar as a powerful technique for reducing soil Cd pollution. These results highlighted the potential of biochar for Cd remediation and crucial role that pyrolysis temperature plays in determining biochar's characteristics and adsorption capacity.