The Batch Adsorption Process of Basic Dyes Using Dialium Cochinchinensis Seed Activated Carbon: Kinetics and Isotherms

The seeds of Dialium cochinchinense, an agricultural byproduct, were converted into an eco-friendly and cost-effective activated carbon (DSAC) for the adsorption of basic dyes, namely Rhodamine B (RB) and Crystal Violet (CV), from aqueous solutions. Batch adsorption experiments were performed to evaluate the effects of key parameters, including initial dye concentration, contact time, adsorbent dosage, and solution pH. The adsorption kinetics followed the pseudo-second-order model, indicating that chemisorption may play a role in the adsorption process. Equilibrium data were best fitted by the Langmuir isotherm model, with correlation coefficients (R²) close to 1, suggesting monolayer adsorption. The maximum adsorption capacities (qₘ) were 416.67 mg g⁻¹ for RB and 526.32 mg g⁻¹ for CV at 30 °C. These results demonstrate that DSAC is a sustainable, efficient, and economically viable adsorbent with strong potential for industrial wastewater treatment applications.