Engineered surface modification of Terminalia chebula for augmented dye eradication from wastewater

Search for greener alternatives for dye-contaminated wastewater treatment is on the rise. The study presents an eco-friendly approach for treating dye-contaminated wastewater using a surface-modified phytosorbent, Terminalia chebula (TC), which has been strategically activated using sodium hydroxide followed by citric acid. Alkali treatment reduces hydrophilic components, enhancing water stability, while citric acid introduces carboxylic groups that improve dye adsorption. Characterization via FTIR, FESEM-EDX and BET confirmed the presence of polyphenols, porous tube-like structures, and a surface area of 3.79 m²/g. pH_zpc of the material is 4.50. The experimentally determined adsorption capacities for CV and MB were 59.19 mg/g and 59.50 mg/g, respectively, at an initial concentration of 1000 mg/L, under optimal conditions (45 min, 0.1 g dose, pH 7). High adsorption capacity despite low surface area highlights the dominant contribution of functional-group-mediated chemical interactions. Adsorption followed pseudo-second order kinetics; CV fit the Temkin isotherm, and MB fit the Langmuir isotherm models. The material was reusable for three cycles with methanol regeneration in CV, and HCl in MB, and common ions caused minimal interference. Taken together, the results suggest that Terminalia Chebula can serve as an environmentally benign option for CV and MB removal from various wastewater matrices.