Rapid adsorptive and optimization of batch process for removal of methylene blue using hybrid GA@SnO2-AC composite materials

Abstract

Methylene blue poses different health risks to humans and harms the environment. The current research developed a hybrid adsorbent combining gallic acid and tin oxide, with the addition of activated carbon, to mitigate the detrimental impact of methylene blue effluent pollution. The adsorptive characteristics of GA@SnO₂-AC were validated using the point of zero charge, SEM-EDX, FTIR, and TGA. The variables that determine dye adsorption were examined. The highest adsorption capacity of 95.24 mg/g was achieved. The experiment data matched with Langmuir model and PSO, indicating the applicability of the MB dye uptake. The R_L values range from 0.6880 to 0.7280, suggesting a favourable process. Thermodynamic investigation showed negative values for ΔH^o (-23.1196) and ΔS^o (-0.0442), indicating an exothermic adsorption system with random subsidence by adsorbed species. The negative ΔG° values (-9.9540 to -8.6286 kJ/mol) indicate the spontaneity and viability of the adsorption system. The optimum conditions for MB adsorption onto GA@SnO₂-AC were obtained at an adsorbent dosage of 50 mg, a concentration of 58 mg/L, a contact time of 48 min, and a pH of 11.0, with a desirability of 1. The results indicated that 98.64% of the MB dye had been removed. The model validation results showed 98.13%, indicating an excellent fit between the predicted and actual values. The GA@SnO₂-AC showed excellent stability and regeneration ability towards MB, with a removal efficiency of 86.66% at its five repeated adsorption-desorption cycles. This current study establishes the basis for the possible development of environmentally friendly and economical treatment methods, providing novel opportunities to address key environmental concerns in the water treatment sector.