Assessment of the performance of an acid-activated composite made of Na-montmorillonite Algerian clay to remove phenol and 4-chlorophenol from water

Intrinsic factors such as porosity, surface area, surface changes and pH dominate clay mineral performance. In this work, we evaluated the efficacy of an Algerian local acid-activated clay called bentonite (mostly composed of minerals of the smectite type, such as montmorillonite). The clay was treated with 1 M of H 2 SO 4 and assessed for its ability to adsorb phenol and 4-chlorophenol from aqueous solutions. We analyzed the clay samples using various analytical techniques, including X-Ray Fluorescence (XRF) spectrometry, X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM), and FT-IR spectroscopy. Additionally, using the Brunauer-Emmett-Teller (B.E.T) method, we calculated the pore volume, typical pore diameter, and surface area. According to the findings, the acid-activated clay provided an adsorption capacity of 28.32 and 29.33 mg/g for phenol and 4-chlorophenol, respectively, leading to an elimination rate for such pollutants of 95 % and 98 %, accordingly, after 120 minutes of contact at equilibrium conditions. The most effective adsorption occurred at pH 4, with a decreasing trend observed as pH varied. Higher initial pollutant concentrations resulted in increased adsorption. A good fit was achieved between experimental adsorption equilibrium values and the Langmuir equation. The adsorption process, determined to be spontaneous and exothermic, was best described by a pseudo-first-order kinetic model. This study concludes that the acid activation process enhances the adsorption properties of clay. The process expands the clay's surface area and generates new active sites for pollutant adsorption.