Spherically shaped pectin-g-poly(amidoxime)-Fe complex: A promising innovative pathway to tailor a new material in high amidoxime functionalization for fluoride adsorption.

Pectin was hydrolyzed and was processed in spherically-shaped structure through calcium crosslinker. The synthesized spherical-bead structure was surface functionalized by acrylonitrile grafting reaction, which extends the applications of pectin followed by derivatization with hydroxylamine. The matrix was further decorated with the iron metal to enhance the practical applicability in the aqueous system. The chemical structures were characterized via gravimetric analysis, FTIR, SEM-EDX, elemental analysis, XPS and XRD. The results supported the exceptional uniformity with the presence of substantial receptor amidoxime groups in morphology and elemental composition. The process of adsorption was concluded with good adsorption capacity with iron-impregnated-amidoxime. The presence of S2O32-, SO42-, and NO3- had an insignificant influence on fluoride uptake excluding Cl- and PO43- in a binary/mixture solutions. The adsorption data were excellently expressed by the Freundlich isotherm model (R2 > 0.998) which suggests that the surface of the ligand is multifunctional. The kinetic data was determined and pseudo-second-order rate equation showed well-fit (R2 > 0.998) to the presented data. The findings indicate that Fe-impregnated poly(amidoxime) is a cost-effective and eco-friendly promising adsorbent for fluoride removal even at trace level and a wide optimum pH range due to better aqueous dispersibility of pendent groups responsible for the sorption application.