DOI: https://doi.org/10.55373/mjchem.v25i4.84

Keywords: Adsorption; Moroccan clay; regeneration; methylene blue

Abstract

The objective of this work was to study the capacity of raw Moroccan clays in removing an organic micropollutant, methylene blue (MB), from an aqueous environment. The chemical composition, mineralogical phase, surface functional groups and surface morphology of the adsorbents used were examined using X-ray Fluorescence (XRF), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and scanning electron microscope (SEM) techniques. Experimental factors influencing adsorption such as adsorbent mass, initial pH of the solution, adsorbate initial concentration, adsorbent-adsorbate contact time as well as temperature were investigated. The kinetic study showed that the adsorption process was explained by a pseudo-second-order reaction and the contact time was 30, 45 and 60 min respectively for Red Clay (RC), Green Clay (GC), and White Clay (WC) samples. The isotherm data showed that the Langmuir model was most appropriate to describe the adsorption of MB by the three samples. The maximum adsorption capacities obtained using the Langmuir model were 50.47, 32.57, and 16.78 mg g-1 respectively for RC, GC, and WC. The thermodynamic parameters indicated that MB adsorption onto all clays was endothermic and spontaneous. The regeneration study showed that the adsorbents used were recyclable but showed a decrease of their adsorption capacity. Therefore, RC, GC and WC could be used for the treatment of wastewater contaminated by MB and similar organic compounds.