Effects of Pyrolysis Temperature and Chemical Modification on the Adsorption of Cd and As(V) by Biochar Derived from Pteris vittata

Abstract

Phytoremediation can be applied successfully to solve the serious worldwide issue of arsenic (As) and cadmium (Cd) pollution. However, the treatment of biomass containing toxic elements after remediation is a challenge. In this study, we investigated the effective use of biomass resources by converting the As hyperaccumulator P. vittata into biochar to adsorb toxic elements. Plant biomass containing As was calcined at 600, 800, and 1200 °C, and its surface structure and adsorption performances for As(V) and Cd were evaluated. Pyrolysis at 1200 °C increased the specific surface area of the biochar, but it did not significantly affect its adsorption capacity for toxic elements. The calcined biochar had very high adsorption capacities of 90% and 95% for As(V) and Cd, respectively, adsorbing 6000 mmol/g-biochar for As(V) and 4000 mmol/g-biochar for Cd. The As(V) adsorption rate was improved by FeCl3 treatment. However, the adsorption capacity for Cd was not significantly affected by the NaOH treatment. In conclusion, it was found that after phytoremediation using P. vittata biomass, it can be effectively used as an environmental purification material by conversion to biochar. Furthermore, chemical modification with FeCl3 improves the biochar’s adsorption performance.