Efficiency of the removal by adsorption of Orange Acid 7 and Indigo Carmine in water for the treatment of textile industry effluents

The search for efficient methods for the removal of organic dyes in textile industry effluents is a permanent quest. The objective of the present work is to determine the effective conditions for the removal by adsorption of two azo dyes, Orange Acid 7 (OA7) and Indigo Carmine (IC) regularly contained in the effluents of certain textile industries. To achieve this, the adsorbent was produced from the shell of the Detarium Microcarpum kernel and then characterized by determining its surface function, structure, morphology and specific surface area. The adsorption efficiency was determined by following certain parameters determining the adsorption capacity such as contact time, pH of the effluent, initial concentration of pollutants. The kinetics and adsorption mechanisms were also studied. The results obtained reveal that the adsorbent produced is micro and macroporous with a specific surface area equal to 905.76 m²/g. The main chemical functions identified on its surface are C O, N-H, O-H, C C. The equilibrium time for the adsorption of OA7 and IC is 10 min with a maximum reduction rate of 97 %. The adsorption is optimal at pH = 4 of the solution. The adsorption capacity increases with the initial concentration of the dyes. Acid Orange 7 is adsorbed in a monolayer and Indigo Carmine in a multilayer. The adsorption is generally governed by the pseudo-second-order kinetic model. The maximum adsorption capacity of both dyes on the adsorbent is approximately 27 mg/g.