Elimination Study of Anionic Dye by Co-products of the Phosphate Industry: Kinetics and Thermodynamic

Abstract

Water is essential for all living things however its pain has become serious. Many industrial activities cause pollution by the release of polluting byproducts. Wastewater treatment is hence necessary. In this context, the wastewater of the textile industry containing Red Acid 52 was treated by the solid waste of the washed natural phosphate byproduct. Natural phosphate was also studied. The solid materials were first characterized by chemical analysis, Fourier Transform Infrared spectroscopy (FTIR), and X-ray diffraction (XRD). The phosphate materials were after that, tested in the adsorption of the Red Acid 52. The experimental data indicated that the phosphate waste rock allowed the removal of Red Acid 52. Its maximum retention capacity attained 18.4 mg.g-1. Calcinations of materials inhibit the removal capacity found reduced by 60 to 70%. The adsorption kinetics of the Red Acid 52 on the material is well described by the pseudo-second-order model while the adsorption isotherms are identified by the Langmuir model. Hereafter, the thermodynamic study revealed that the adsorption process is spontaneous and exothermic. The obtained results indicated that the adsorbent has the best adsorption capacity of 18.4 mg.g-1. The removal quantity decreases when the adsorbent is calcined. The kinetics model most appropriate is the pseudo-second-order model. As for the adsorption isotherms, they are well described by the Langmuir model. The temperature effect indicates a decrease in the adsorbed amount with the increase of temperature. Furthermore, the adsorption is spontaneous and exothermic and the reaction is physical in nature for both materials.