The Application of Natural Clay Adsorbents for the Removal of Reactive Red 120 Dye from the Industrial Textile Effluents: Modelling, Kinetics and Thermodynamic Study

Textile dyeing industries release huge amounts of dyes and chemicals, which is a major concern of many country's politics because dyes may affect the environment and are toxic to living organisms. In the present work, the removal of anionic dye (Reactive Red 120) from textile effluents by using clay samples as adsorbents, were carried out using Tunisian raw clays (Tabarka and Fouchana). Various parameters were investigated such as the contact time, the mass of the adsorbent, the initial dye concentration, the ionic strength, the pH of the aqueous phase, the temperature, and the supplement of chemicals existing in the textile dyeing industrial effluents. The results showed that the kaolinite-rich clays had a higher discoloration efficiency for the anionic dye, and that the adsorption was enhanced at high ionic strength, low pH, and in presence of the additive CHT Catalase derived from enzymatic products. On the contrary, the additive Cotoblanc had a negative effect. The adsorption kinetics followed the pseudo-second-order model. At equilibrium, the adsorption isotherms were well described by the Langmuir model. Finally, the adsorption process of the dye onto raw clay was feasible and spontaneous at ambient temperature, but the temperature increase greatly decreased the adsorption capacity.