A Novel Chitosan/Nano-Hydroxyapatite Composite for the Adsorptive Removal of Cd(II) from Aqueous Solution

• Published in: Polymers Vol. 15; no. 6; p. 1524
• Main Authors: El Kaim Billah, Rachid, Ayouch, Ikrame, Abdellaoui, Youness, Kassab, Zineb, Khan, Moonis Ali, Agunaou, Mahfoud, Soufiane, Abdessadik, Otero, Marta, Jeon, Byong-Hun
• Format: Journal Article
• Language: English
• Published: Switzerland MDPI AG 19.03.2023; MDPI
• Subjects: Activated carbon; Adsorbents; Adsorption; adsorption mechanism; Adsorptivity; Aqueous solutions; bio-composite; Biopolymers; Cadmium; Cellulose; Chemical bonds; Chemical properties; Chemical synthesis; Chitosan; Crystals; Heavy metals; Hydroxyapatite; Membrane separation; Molecular weight; nano-hydroxyapatite; Nitrates; Organic contaminants; Polymers; Structure; Thermal properties; Thermodynamics; Viscosity; Morocco; Germany; chitosan; nano-hydroxyapatite; cadmium; bio-composite; adsorption mechanism
• ISSN: 2073-4360; 2073-4360
• DOI: 10.3390/polym15061524

A novel polymer bio-composite based on nano-hydroxyapatite (n-Hap) and chitosan (CS) (CS/n-Hap) was synthesized to effectively address toxic cadmium ions removal from water. The composition and structure of CS/n-Hap bio-composite were analyzed through different characterization techniques. XRD patterns affirmed that the crystalline structure of n-Hap remained unaltered during CS/n-Hap synthesis, while FT-IR spectrum sustained all the characteristic peaks of both CS and n-Hap, affirming the successful synthesis of CS/n-Hap. Adsorption studies, including pH, adsorbent dosage, contact time, initial Cd(II) concentration, and temperature, were carried out to explain and understand the adsorption mechanism. Comparatively, CS/n-Hap bio-composite exhibited better Cd(II) adsorption capacity than pristine CS, with an experimental maximum uptake of 126.65 mg/g under optimized conditions. In addition, the kinetic data were well fitted to the pseudo-second-order model, indicating the formation of chemical bonds between Cd(II) and CS/n-Hap during adsorption. Furthermore, the thermodynamic study suggested that Cd(II) adsorption onto CS/n-Hap was endothermic and spontaneous. The regeneration study showed only about a 3% loss in Cd(II) uptake by CS/n-Hap after five consecutive cycles. Thus, a simple and facile approach was here developed to synthesize an eco-friendly and cost-effective material that can be successfully employed for the removal of toxic heavy metal ions from water.