Applied Journal of Environmental Engineering Science
Abstract
Activated carbon obtained from Detarium microcarpum seed shell (SDAC) was used to eliminate congo red (CR) from an aqueous solution using batch adsorption method. Various characterization techniques, including SEM, FT-IR and pH at point of zero charge (pHpzc) were employed to characterize the adsorbent surface. The study investigated several adsorption parameters, namely contact time (5 - 150 minutes), temperature (303 - 323 K), and initial concentration (20 - 500 mg/L). The adsorption data were analyzed using kinetic, isotherm, and thermodynamic equations. The kinetics of the process conformed well to the pseudo-second-order model, indicating that both external and internal diffusion influenced the adsorption of the dye onto the adsorbent. The isotherm data aligned with the Freundlich model, suggesting that CR formed multiple layers on the heterogeneous surface of the adsorbent. The values of thermodynamic calculations ∆S = -0.139 kJ/mol, ∆H = - 48.77 kJ/K demonstrates the feasibility and exothermic nature of the dye adsorption process and the values of ∆G = -6.52, -5.82, -5.12, -4.42 and -3.73 kJ/mol obtained at various temperature confirmed the spontaneity of the entire adsorption process
