Evaluation of the adsorptive removal of cationic dyes by greening biochar derived from agricultural bio-waste of rice husk

Abstract

In this study, biochar derived from agricultural bio-wastes of rice husk was used as a biosorbent for dye sequestration of Basic Blue 41 (BB41) and Basic Red 09 (BR09) from the aqueous solution. The structural characteristics of the biochar were performed through TGA, BET, SEM, EDX, and FTIR. The experimental conditions proved that 80% of dye removal was attained in the optimal operating conditions (dosage of 6 g L−1 (BB41), 1 g L−1 (BR09), pH of 7 (BB41) and 8 (BR09), temperature of 35 °C, and initial dye concentration of 50 mg L−1). Four different isotherms models were used to describe the adsorption process. Based on the correlation coefficient and percentage of error values, BB41 and BR09 sorption revealed that Langmuir model has better fit when compared to other models. The maximum adsorption capacities of BB41 and BR09 on rice husk biochar are 17.596 mg g−1 and 168.49 mg g−1, respectively. The thermodynamic parameters △H < 0 and △G < 0 indicated that the whole adsorption process of rice husk biochar to BB41 and BR09 is exothermic and spontaneous at low temperature. The regeneration studies were carried out with different elutants to confirm the elution efficiency of the sorbent. The results indicate the biochar derived from agricultural bio-waste of rice husk was a potentially greening biosorbent for the dye sequestration from wastewater.