Nano iron oxide impregnated in chitosan bead as a highly efficient sorbent for Cr(VI) removal from water

• Published in: Carbohydrate polymers Vol. 173; pp. 28 - 36
• Main Authors: Lu, Jianbo, Xu, Kai, Yang, Jinmei, Hao, Yarong, Cheng, Fang
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 01.10.2017
• Subjects: Adsorption; Chitosan; Hexavalent chromium; Nano iron oxide; Reduction; Sorbent bead; Nano iron oxide; Hexavalent chromium; Reduction; Ferric chloride (PubChem CID: 24810); Adsorption; Sorbent bead; Chitosan (PubChem CID: 21896651); Chitosan; Potassium dichromate (PubChem CID: 24502); 1,5-Diphenylcarbazide (PubChem CID: 8789)
• ISSN: 0144-8617; 1879-1344
• DOI: 10.1016/j.carbpol.2017.05.070

•Nano Fe oxide impregnated in chitosan bead (NIOC) for Cr(VI) removal was fabricated.•NIOC synthesis was facile only using ferric salts and chitosan in alkaline solutions.•NIOC sorbent had high sorption capacity towards Cr(VI) (69.8mg/g, pH 5).•Proposed mechanisms involved sorption, reduction of Cr(VI) to Cr(III) and re-sorption.•Saturated NIOC could be effectively regenerated by NaOH solution and reused. Using Fe(III) salts and chitosan, nano iron oxide impregnated in chitosan bead (NIOC) was successfully synthesized for aqueous Cr(VI) detoxification via sol-gel technique without any additional crosslinking agent. NIOC characterization demonstrated that the iron in NIOC mainly existed as nano akaganeite (β-FeOOH) and complex with chitosan. Intraparticle diffusion was the major rate-limiting step. The maximal adsorption capacity was 69.8mg/g (pH 5.0, 20°C). Normal concentration of coexisting anions (SO42−, CO32−, SiO32−) showed insignificant competition, whereas PO43− suppressed the Cr(VI) sorption. Cr(VI)-loaded NIOC could be effectively regenerated by alkaline solutions. Column adsorption runs using granular NIOC could effectively treat about 1600 bed volumes of Cr(VI) solution (from 3.7mg Cr/L in influent to <0.5mg Cr/L in effluent). The Cr(VI) removal mechanisms involved the direct sorption of Cr(VI) (electrostatic attraction and ligand exchange), reduction of Cr(VI) into Cr(III) and re-sorption of Cr(III) via chelation on NIOC surface.