Efficient removal of Congo red and methylene blue using biochar from Medulla Tetrapanacis modified by potassium carbonate.

Biochar (BC) prepared from Medulla Tetrapanacis was recognized as having potential in environmental remediation because of its porous texture, abundant chemical surface groups and mineral composition. In this study, a novel modified biochar (KBC) derived from Medulla Tetrapanacis achieved efficient adsorption of Congo red (CR) and methylene blue (MB). Characterization results suggested that the modification had little effect on the group distribution of KBC, but a dramatic expansion of specific surface area was observed on KBC (1180.45 m/g) compared to BC (198.51 m/g). KBC exhibited a maximum sorption of 584.17 mg/g for CR and 318.01 mg/g for MB. Kinetic and isotherm studies revealed sorption of CR and MB by KBC was chemosorption, which occurred on the monolayer surface. The comprehensive analysis also provided the basis for the application of KBC to practical production. These outcomes suggested that KBC may become a new option for the effluent treatment.