Alginate/Phosphine-Functionalized Chitosan Beads Towards the Removal of Harmful Metal Ions from Aqueous Medium

• Published in: Journal of polymers and the environment 2023, Vol.31 (1), p.249-263
• Main Authors: de Souza, Jaqueline F., da Silva, Emilly C., Biajoli, André F. P., Bonemann, Daísa H., Ribeiro, Anderson S., Fajardo, André R.
• Format: Article
• Language: English
• Subjects: Adsorbents; Adsorption; Alginates; Alginic acid; Aluminum; Aqueous solutions; Beads; Binding sites; Cadmium; Chemistry; Chemistry and Materials Science; Chitosan; Environmental Chemistry; Environmental Engineering/Biotechnology; Functional groups; Industrial Chemistry/Chemical Engineering; Materials Science; Metal ions; Metals; Original Paper; pH effects; Phosphine; Phosphines; Polymer Sciences; Polysaccharides; Scanning electron microscopy; Thermogravimetric analysis; X-ray diffraction
• ISSN: 1566-2543; 1572-8919
• DOI: 10.1007/s10924-022-02599-8

Among the many strategies utilized to improve the adsorption capacity of adsorbent materials, the modification of their chemical nature has been widely exploited, especially considering the polysaccharide-based adsorbents. Based on this, a phosphine-functionalized chitosan derivative (CSPPh 2 ) was associated with alginate (Alg), resulting in beads that were utilized to adsorb Cd 2+ and Al 3+ from water. After a complete characterization [Fourier transformed infra-red (FTIR), X-ray diffraction (XRD), thermogravimetric analyses (TGA/DTG), scanning electron microscopy (SEM), swelling analysis, and pH of point of zero charge (pH PZC )], adsorption experiments were performed to determine the optimal operational conditions. Under similar conditions, the Alg/CSPPh 2 showed superior adsorption performance compared to the beads prepared using raw chitosan. Moreover, the maximum adsorption capacities for Cd 2+ (78.2 mg/g) and Al 3+ (81.5 mg/g) were computed to Alg/CSPPh 2 beads under mild conditions (pH 6.0, 25 °C, 50 mg of adsorbent). The adsorption process for both metals was well-fitted by the pseudo-first-order kinetics and Freundlich isotherm model. Overall, the adsorption of these metals on Alg/CSPPh 2 occurred via physical interaction forces, and the functional groups on the beads, including the –PPh 2 groups, have a pivotal role as binding sites. The post-utilized beads could be regenerated and reused up to 5 times consecutively with a slight decrease in their removal capacity. This study demonstrated that these original beads containing phosphine-functionalized chitosan are enhanced adsorbents to remove metal ions of different valences from the water environment.