Enhanced Removal of Nickel from Aqueous Solutions Using Carbonated Moroccan Clay: Characterization, Adsorption and Thermodynamic Studies

Utilizing clay for adsorbing heavy metals from water presents a promising approach for efficiently eliminating these contaminants, offering an encouraging option for environmental remediation. This research explores the adsorption capability of locally sourced carbonated raw clay (RC) from Fez region in North-East Morocco as a naturally abundant and low environmental impact adsorbent for efficiently eliminating nickel (Ni) from water solutions. The high carbonate content limits the valorization of this clay in other fields as a building material or in the ceramics industry. The clay underwent detailed characterization of its physical and chemical properties using different analytic techniques (XRF, TGA/DTG, FTIR, XRD, SEM, and EDX). To establish the optimal operating conditions for removing nickel using RC, a series of batch adsorption tests were conducted. These experiments explored the impact of the temperature, Ni concentration, contact duration, adsorbent dose, and initial pH. Additional investigations into kinetics, equilibrium, and thermodynamics were performed to enhance comprehension of the adsorption mechanism. Considering error function and correlation coefficient values, the pseudo-second order model best described the kinetic data, implying a chemisorption-based process. Moreover, the examination of adsorption isotherm results demonstrated the isotherm of Sips as the most fitting model, revealing a maximum adsorbed amount of 59.163 mg/g. Evaluation of thermodynamic factors revealed the endothermicity, favorability, and spontaneity of the adsorption process.