Iron Modification of Biochar Developed from Tectona grandis Linn. F. for Adsorptive Removal of Tetracycline from Aqueous Solution

Abstract

Iron-modified biochar was prepared using woody biomass of Tectona grandis Linn f. for the removal of tetracycline from an aqueous solution. The prepared biochar was characterized by Fourier transformed infra-red spectroscopy, Scanning electron microscope, and X-ray photoelectron spectroscopy. The FTIR results showed predominant peaks that confirm the alignment of iron oxide on the surface of the biochar. Similarly, the surface of the iron-modified biochar constitutes a graphite sheet-like structure with irregular projection and peaks fit by XPS further provided evidence for the successful establishment of iron on the surface. The adsorption experiment was subjected to different equilibrium models namely Langmuir Freundlich and Temkin, where Langmuir was found to be best fitted for adsorption. The maximum adsorption capacity was found to be 62.5 mg g-1 at optimal experimental conditions. Pseudo second order with a better correlation coefficient (R2=0.985) and rate constant (k =0.021) supported the chemical sorption hypothesis of tetracycline on biochar. The adsorption mechanism is well explained by the results obtained which supports surface interaction between biochar and tetracycline (TC). The thermodynamic parameters revealed that the process of adsorption was spontaneous and feasible (ΔG°<0) while the reaction was found to be endothermic (ΔH°=152.2J mol-1) where randomness (ΔS°=60.88J mol-1) increases at the solid-liquid interface.