Fe(III)–Chitosan Microbeads for Adsorptive Removal of Cr(VI) and Phosphate Ions

Abstract

Fe(III)–chitosan microbeads (Fe–CTB) were prepared using a chemical coprecipitation method. SEM–EDX, FTIR, XRD, TGA, BET, and pH pzc were performed for the characterization of the adsorbent. Various parameters were optimized as pH, adsorption time, adsorbent dose, initial Cr(VI), and PO43− ion concentration and the effect of assorted ions for adsorption studies. Fe–CTB microbeads revealed more than 80% detoxification for a 100 mg L−1 initial concentration at pH 3 with 60 min stirring of Cr(VI) and PO43− ion having adsorption capacities of 34.15 and 32.27 mg g−1, respectively. The adsorption process for Cr(VI) and PO43− ion followed the monolayer adsorption as they favored the Langmuir isotherm model. Kinetic and thermodynamic studies’ emphasis on the adsorption process was spontaneous and exothermic with pseudo-second-order kinetics for both adsorbates. The microbeads were found to be reusable in multiple cycles.

Keywords

• chitosan
• Fe(III)–chitosan composite
• chromate
• phosphate
• adsorption