Abstract
In recent years, the application of activated carbons derived from waste biomass precursors with well-developed pores and extended specific surface area has evinced considerable interest for environmental contaminant abatement. Microwave irradiation is a promising energy-efficient and environmentally significant technique for activated carbon preparation. The present work intends to accentuate the utilization of activated carbon based on sustainable and plentifully available waste biomass - goat droppings - and its subsequent usage in aquatic environmental remediation. In the present article, the efficiency of goat droppings activated carbon (GDAC), prepared via energy-efficient microwave irradiation using H3PO4 as chemical activator, for the removal of coomassie brilliant blue G 250 (CBB) from aqueous solution, has been examined. The operating variables influencing the adsorption process are optimized using response surface methodology (RSM) through central composite design (CCD). The optimum conditions for CBB adsorption are contact time (100 min), pH (3.98), initial CBB concentration (80 mg/L), GDAC dose (0.35 g/L), and temperature (333 K). The interaction of process variables is evaluated through statistical analysis of the developed regression model in CCD and three-dimensional response surface plots. The Freundlich model efficiently elucidates the experimental data, which amounts to the adsorption of CBB onto heterogeneous GDAC surface. The monolayer adsorption capacity (270.3 mg/g), evaluated from the Langmuir model, establishes the high removal efficiency of GDAC in comparison to earlier reported adsorbents proving its superior performance. The adsorption appropriately follows pseudo-second-order kinetics. The negative Delta Go (4.20-5.20 kJ/mol at 60 mg/L; 3.57-4.15 kJ/mol at 70 mg/L) and Delta Ho (5.93 kJ/mol at 60 mg/L; 2.29 kJ/mol at 70 mg/L) confirm the spontaneous and endothermic and physical nature, respectively, of the adsorption process. The study demonstrates that the present adsorbent can be proficiently employed in the treatment of dye-based water.