Methyl Orange Adsorption on Biochar Obtained from Prosopis juliflora Waste: Thermodynamic and Kinetic Study

In the information contained herein, we fabricated biochar by means of a pyrolysis process; it used Prosopis juliflora waste (PJW) as a biomass source. The physical and chemical material characterization was carried out through FTIR, thermogravimetric, BET-N-2 isotherm, and SEM-EDX assays. We studied the methylene orange (MO) adsorption onto PWJ biochar. The PJW biochar displayed a maximum percentage of MO removal of 64%. The results of the adsorption study indicated that Temkin isotherm was suitable to describe the MO adsorption process on PJW biochar; it suggests that the MO adsorption on PJW biochar could be a multi-layer adsorption process. Results showed that the pseudo-second-order model was accurate in demonstrating the MO adsorption on PJW (k(2) = 0.295 g mg(-1)min(-1); q(e) = 8.31 mg g(-1)). Furthermore, the results made known that the MO removal by PJW biochar was endothermic (Delta H = 12.7 kJ/mol) and a spontaneous process (Delta G = -0.954 kJ/mol). The reusability test disclosed that after four consecutive adsorption/desorption cycles, the PWJ biochar reduced its MO removal by only 4.3%.