Study of acid treatment effect of a natural red clay onto physico-chemical and adsorption properties
Hassan Ouallal, Mohammed Chrachmy, M. Azrour, Mahdi Lechheb, Abderrazek El–Kordy, Younes Dehmani, Hammou Moussout, Azdouz M’barek
Abstract
ABSTRACT The aim of this work is the study of phenol adsorption in aqueous medium onto raw red clay (RRC) and treated red clay (TRC) from the Drâa–Tafilalet region. The treated clay was obtained by two attacks, the first with hydrogen peroxide and the second with hydrochloric acid. The two samples were characterized by various physico-chemical methods, namely fluorescence-X, Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), thermogravimetric analysis, differential thermal analysis, and Brunauer–Emmett–Teller technique. These methods indicate that the clay is mainly composed of silica, and alumina, for which chemical treatment is justified by the elimination of carbonate and the increase in a special surface area from 40.962 for RRC to 64.264 for TRC. Phenol adsorption tests showed that equilibrium was reached after 200 min of agitation for adsorbents at different temperatures (30°C, 40°C, and 50°C), with maximum adsorption yields equal to 3.53 for RRC and 4.88 for TRC. The non-linear modeling indicates that the pseudo-second-order model describes the adsorption kinetics. In contrast, the corresponding adsorption isotherms follow the Langmuir and Redlich–Peterson models for the two adsorbents. This shows that the adsorption is done initially on the monolayer and then moved on to the multilayer. FTIR and XRD analysis of the adsorbents after adsorption show that the phenol was adsorbed and penetrated into the interlayer space, resulting in an expansion of the interlayer space.