PHYSICOCHEMICAL CHARACTERIZATION AND COMPARATIVE EVALUATION OF BIOCHAR MATERIALS FOR HEAVY METAL ADSORPTION

Abstract

Due to its attractive physicochemical characteristics and production from various biomass feedstocks, biochar has shown potential as a sustainable adsorbent for heavy metal remediation. But, due to the differences between feedstock and pyrolysis conditions, significant differences in adsorption performance are obtained, indicating the need of systematic comparative evaluation. The present study compared the physicochemical properties of various biochar materials and examined the correlation between the physicochemical properties and the adsorption performance of Pb and Cd by biochar by using a secondary open access data set. A compiled data set of adsorption records of Pb and Cd, as well as physicochemical properties, pyrolysis conditions, and adsorption performance indicators were analysed quantitatively. Descriptive statistics, comparative analysis, correlation analysis and multiple linear regression were used to evaluate the effect of physicochemical properties on the adsorption of heavy metals. Results indicated a significant variation among the materials in pyrolysis temperature, specific surface area, pore characteristics, elemental composition and biochar pH. Similarly, adsorption capacity and removal efficiency for both Pb and Cd were greatly different depending on different biochar feedstocks. The regression analysis revealed that the initial concentration of the metal was the best predictor of adsorption capacity, and the other variables (physicochemical properties) also influenced the adsorption capacity. Conclusively, systematic physicochemical characterization is important to choose efficient biochar materials for removing heavy metals. The results offer insights for further development of the biochar-based adsorbents and the utilization in sustainable water treatment and environmental remediation.