Efficient removal of asphaltene and organic dyes using hybrid magnetic Nanomaterials: Adsorption selectivity and comparative study

The current paper concerns the preparation of several magnetic mesoporous nanocomposite using the Na-montmorillonite, MOF MIL-101 (Cr), MCM-41 calcined and uncalcined as a matrix, the obtained nanocomposites were used as adsorbent to remove the methylene blue, orange G dyes and asphaltenes. The materials were characterized by XRD, FTIR, SEM, HR-TEM, STEM, EDS, SAED, AFM, N² adsorption–desorption and zeta potential in order to investigate the structural, textural and morphological properties. The adsorption was studied in-depth by evaluating the impact of contact time, the initial concentration, the temperature and the pH effect. This study details all aspects of the asphaltenes and other major organic pollutants adsorption by several types of mesoporous materials. The results suggest that the organic dyes removal follow the Langmuir isotherm, the pseudo-second order and endothermic process which confirm the chemisorption, while the asphaltenes adsorption is a physisorption mechanism following the Freundlich isotherm, the pseudo-second order and an exothermic process. The maximal adsorbed quantities obtained were 495.050 and 116.414 mg/g towards the MB and asphaltenes using the MMT@Fe₃O₄ and 230.947 mg/g against the OG using the MCM@Fe₃O₄. The MOF@Fe₃O₄ was the only adsorbent showing an excellent adsorption capacity against all pollutants with 395.257, 198.020 and 109.170 mg/g towards the MB, OG and asphaltenes respectively, which is mainly due to its surface charge, porosity and the high surface area reached 892.5003 m²/g. A comparative study was carried out between these materials and the literature and a high superiority of these adsorbents has been noticed. Finally, a detailed mechanism of the asphaltenes and organic dyes is established to allow a better comprehension of the adsorption phenomena.