Gustave Tchanang^{1, 2,}, Jean M. Kepdieu², Kalaya Goumou¹, Mamadou Y. Baldé^{2, 3}, Cyprien J. Ekani², Chantale N. Djangang², Phillipe Blanchart⁴

Experimental and theoretical investigations related to the adsorptive removal of Basic blue 9 (BB9) onto γ-Al₂O₃ (gamma-Nano alumina) have been done in the present work. Batch tests were carried out varying some processing parameters namely initial dye concentration (5 - 50 mg/L), adsorbent dose (0.5 - 5 g/L), initial pH (1 - 12) and contact time (0 - 30 min). Under conditions of C₀ = 50 mg/L; pH = 11; dose = 1g/L and t = 15 min, more than 83.6% of the BB9 molecules were removed corresponding to an adsorption capacity of 41.8 mg/g. The pseudo-second order and the Langmuir models fit well the experimental data with highest R² values of 0.99 and 0.91 respectively and lowest values of χ². This suggests adsorption process as limiting step on a homogeneous distribution of active sites on the adsorbent surface. The first step of adsorption mechanism involved electrostatic interactions between the negatively charged γ-Al₂O₃ surface in basic medium and secondly electrophilic-nucleophilic interactions. Compared to other adsorbents, γ-nano Al₂O₃ obtained in this work could be a good alternative for treatment water containing dye BB9.

γ-Nano alumina, Basic Blue 9, Adsorption, Equilibrium, Kinetic and mechanism