Investigating the efficacy of biochar produced from agro-waste for basic fuchsin dye removal: Kinetics, isotherm, and thermodynamic studies

The present article investigates the efficacy of biochar (BC) derived from agricultural waste for treating cationic dyes. Various biomass, including sycamore leaf (SL), cotton waste (CW), groundnut shell (GS), rice husk (RH), coconut shell (CS), banana pith (BP), and coconut husk (CH) were used to prepare biochar at 400, 600, and 800 degrees C. The highest removal of basic fuchsin (BF) dye was observed onto the BC prepared at 800 degrees C, with the removal efficiency as follows: cotton waste biochar (CWB) 88.12%, groundnut shell biochar (GSB) 88.73%, rice husk biochar (RHB) 89.37 %, coconut shell biochar (CSB) 90.4 %, coconut husk biochar (CHB) 91.24 %, banana pith biochar (BPB) 96.7%, and sycamore leaf biochar (SLB) 100%, respectively. The dye concentration, BC dose, reaction time, temperature, and pH were optimized. Optimal conditions for higher BF dye sorption (174.5 mg g(-1)) were found at the dye concentration of 3500 mg L-1, SLB dose of 0.2 g, time 45 min, temperature 40 +/- 2 degrees C, and pH 9 +/- 0.2. The sorption kinetic data best fit a pseudo-second-order model, while isotherm data followed the Freundlich model, suggesting chemisorption with a multilayer sorption process. Thermodynamic data implied that the sorption process was endothermic and spontaneous. The present research revealed the hidden potential of widely and easily available waste biomass to competently remove the cationic dye.