Analysis of the Cd(II) Adsorption Performance and Mechanisms by Soybean Root Biochar: Effect of Pyrolysis Temperatures

As one of the most harmful environmental pollutants, cadmium (Cd) has arisen much interest, and many researches have been carried out to study the adsorption of heavy metals by biochar, but the mechanisms were poorly explored and the roles components in biochar played are still indistinct. In this study, we evaluated the adsorption capacities and mechanisms of soybean root biochar pyrolyzed at four different temperatures. The results indicate the biochar properties are significantly determined by pyrolysis temperature, which affects the removal mechanisms of Cd(II) consequently. Microstructure characteristics and mechanism analysis further suggest that Cd(II)-pi interactions and sulfur-containing functional groups are the main mechanisms of Cd(II) adsorption. This work shows a new perspective to explain the adsorption mechanisms onto biochar adsorbents and has a benefit for the exploitation of economical and effective adsorbents for Cd(II) removal based on biochars.