Reduction of Bromate in Water using Zerovalent Cobalt 2,6-Pyridine Dicarboxylic Acid Crosslinked Chitosan Nanocomposite

Zerovalent cobalt 2,6-Pyridinedicarboxylic acid crosslinked chitosan (ZVCo-PDCA-CHIT) nanocomposite, which was obtained by chemical reduction of cobalt (II) ion chelated nanocomposite with NaBH4, was tested for bromate reduction in water. 2,6-pyridinedicarboxylic acid (PDCA) was used for intramolecular crosslinking of the chitosan linear chains. The products were characterized by FT-IR, XRD and SEM. The FT-IR analyses revealed the presence of coordinating NH2 and OH functional groups in chitosan while crosslinked chitosan showed COOH absorption peaks. The XRD spectrum revealed a typical fingerprint of semi-crystalline chitosan which disappeared in crosslinked chitosan due to disruption of the interpolymer bonds. SEM image revealed a smooth surface for the Chitosan while large pores were observed for the PDCAcrosslinked Chitosan (PDCA-CHIT). ZVCo-PDCA-CHIT nanocomposite showed significant morphological changes with the surface structure being smooth with the disappearance of the holes observed in the crosslinked chitosan structure, indicating a very strong binding of cobalt with most of the functional groups. The applied ZVCo-PDCA-CHIT nanocomposite reduced bromate ions to bromide with possible adsorption onto the nanocomposite. The result showed that bromate reduction in water was significantly higher and near completion under 1h using ZVCo-PDCA-CHIT (99 +/- 1.1%) as compared to PDCAcrosslinked Chitosan (65 +/- 1.47%) and Chitosan (53 +/- 0.25%).