Unveiling the potency of Silica-Alumina-rich clay in phenol remediation and its repurposing prospects

Abstract

Clay, renowned for its versatility, plays a pivotal role in various applications including the production of decorative pottery. In this study, a silica and alumina-rich Moroccan clay was employed to adsorb phenol from aqueous solutions. Employing an array of characterization techniques including X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Fourier Transform Infrared Spectroscopy (FTIR), The Brunauer–Emmett–Teller (BET) method and X-ray Fluorescence (XRF), the physical and chemical attributes of the clay were meticulously examined. The adsorption kinetics were expeditiously rapid, occurring within a timescale of approximately twenty minutes, and corresponded with the pseudo-second-order model. The adsorption isotherms aligned with both Freundlich and Langmuir models, illustrating an impressive adsorption capacity nearing 97 mg/g. The clay's physicochemical profile revealed the prevalence of both negative and positive sites, owing to its high silica (over 49%) and alumina (19.5%) content, which enhanced the attraction of nucleophilic sites in phenol. Detailed investigation into the interaction mechanism between phenol and clay demonstrated that the mesomeric forms of phenol in water created nucleophilic sites, which engaged with the positive sites of the silica and alumina phases. Furthermore, physico-mechanical assessments of the clay, both pre- and post-phenol adsorption, revealed no significant alterations in flexural strength, highlighting the potential for reutilizing phenol-loaded clay in pottery production. This revelation marks a step towards integrating pollution control with sustainable resource utilization, leveraging the abundant availability of natural clay materials and their noteworthy adsorptive properties for a variety of pollutants. © 2023 Elsevier B.V.