Chitin extraction from crab shells and synthesis of chitin @metakaolin composite for efficient amputation of Cr (VI) ions

• Published in: Environmental research Vol. 252; p. 119065
• Main Authors: Algethami, Jari S., Jugade, Ravin, Billah El Kaim, Rachid, Bahsis, Lahoucine, Achak, Mounia, Majdoubi, Hicham, Shekhawat, Anita, Korde, Sanjiwani, López-Maldonado, Eduardo Alberto
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier Inc 01.07.2024
• Subjects: Adsorption; Chitin@metakaolin; Composite; Cr(VI) removal; Shrimp waste; Cr(VI) removal; Composite; Adsorption; Shrimp waste; Chitin@metakaolin; adsorption; composite
• ISSN: 0013-9351; 1096-0953
• DOI: 10.1016/j.envres.2024.119065

The present research study combines chitin from shrimp waste with the oxide-rich metakaolin. Metakaolin is a blend of mixed oxides rich in silica and alumina with good adsorbent properties. The chitin@metakaolin (CHt@M.K.) composite was synthesized and characterized using FTIR, SEM, TGA, XRD and XPS techniques. Cr(VI) removal studies were compared for chitin and CHt@M.K. through adsorption. It was found that the adsorption capacity of CHt@M.K. is 278.88 mg/g, almost double that of chitin, at pH 5.0 in just 120 min of adsorption. Isotherm models like Langmuir, Freundlich, Temkin and Dubinin–Radushkevich were investigated to comprehend the adsorption process. It was revealed that Langmuir adsorption isotherm is most suitable to elucidate Cr(VI) adsorption on CHt@M.K. The adsorption kinetics indicate that pseudo first order was followed, indicating that the physisorption was the process that limited the sorption process rate. The positive enthalpy change (20.23 kJ/mol) and positive entropy change (0.083 kJ/mol K) showed that the adsorption process was endothermic and more random at the solid-liquid interface. The negative free energy change over entire temperature range was an indicator of spontaneity of the process. Apart from all these, the non-covalent interactions between Cr(VI) and composite were explained by quantum calculations based models. [Display omitted] •Chitin obtained from the crab shells was loaded over metakaolin forming CHt@M.K.•Adsorptive removal studies of Cr(VI) by CHt@M.K. were carried out.•CHt@M.K. acts as an efficient adsorbent as compared to other homologues. adsorbents.•Mechanistic study was carried out by quantum calculations and molecular models.•Regeneration of the material shows the greener perspective towards the environment.