ÉLIMINATION DU BLEU DE METHYLENE PAR DES ADSORBANTS A BASE D'ARGILE LOCALE DE LUKALA (C206): INFLUENCE DES MODIFICATIONS CHIMIQUES ET ORGANIQUES SUR LES MECANISMES D’ADSORPTION

Abstract

This study aims to comparatively evaluate the potential for removing methylene blue (MB) from aqueous solution using various clay matrices—C₂₀₆-B (raw), C₂₀₆-A (activated), and C₂₀₆-I (impregnated)—from the Lukala region in Kongo-Central. Adsorption tests were conducted by assessing the influence of several key parameters: contact time, pH, and initial dye concentration. The results showed that equilibrium was reached within 60 minutes for all three matrices. Adsorption of the pollutant onto the matrices increased with both solution pH and initial concentration. Methylene blue adsorption kinetics were analyzed using standard pseudo-first-order and pseudo-second-order models; the results indicated that the pseudo-second-order model provided a better fit than the pseudo-first-order model, confirming a chemisorption mechanism. Adsorption equilibrium was modeled using the classic Langmuir and Freundlich isotherms. Experimental results showed the best fit with the Freundlich adsorption model. Maximum adsorption capacity followed the order: C₂₀₆-A (8.61 mg/g) > C₂₀₆-I (8.13 mg/g) > C₂₀₆-B (6.66 mg/g).