Production of Ulva prolifera derived biochar and evaluation of adsorptive removal of Reactive Red 120: batch, isotherm, kinetic, thermodynamic and regeneration studies

A marine seaweed Ulva prolifera was used to produce biochar for the decolorization of Reactive Red 120 (RR120) in aqueous solutions in batch mode operation. The batch results concluded that the biochar has the potential of removing 85.7% of dye molecules with a sorption capacity of 107.13 mg/g. The influencing parameters namely pH, sorbent dose, and temperature were studied and optimum results were obtained at a solute pH of 2, sorbent (biochar) dose of 2 g/L, and temperature of 35 degrees C respectively. Based on the partition coefficient, the optimum initial RR120 concentration was achieved, and a maximum partition coefficient of 3 L/g was obtained at an initial RR120 concentration of 250 mg/L. Further adsorption isotherms namely two, three, and four parameter models, kinetic models, and statistical error analysis were also studied. The desorption experiments were also studied for calculating the desorption efficiency using different elutants, solid to liquid (S/L) ratios, and regeneration cycles. For sodium hydroxide, a desorption efficiency of 99.2% with an S/L ratio of 3 and a regeneration cycle of 2 was achieved.