Electrovalent chitosan functionalized methyl-orange/metal nanocomposites as chemosensors for toxic aqueous anions

Abstract Chitosan functionalized methyl orange (CFMO) nanocomposites of iron (CFMO-FeNPs) and copper (CFMO-CuNPs) were successfully prepared as simple and selective chemosensors for CN − and AsO 4 3 − anions in aqueous solution. The initially synthesized chitosan-dye-metal complexes (CFMO-Fe(II) and CFMO-Cu(II) were nanosized via chemical reduction methods. The imminent IR bands shift especially of ν C − C aromatic rings and CFMO azo bond suggest the formation of cyclometaled metal-azo complexes. Plasmon resonance bands at 473 and 469 nm were observed for the nanocomposites of Fe and Cu respectively indicating successful nano reduction of the metal ions. The semi-crystalline nature of the composites was revealed from the XRD analysis which ranged from broad to sharp peaks. More so, the varying linear orientation to monodispersed distribution of the nanoparticles on the biopolymeric substrate was displayed in the SEM micrographs. The electrostatic attraction between the metal induced cationic N,N-dimethylbenzenamine end and the test anions provides remarkable colorimetric responses with high selectivity for the test anions in an aqueous solution with LOD of 1.0 and 2.0 μ g/mL for CN − and AsO 4 3 − respectively. Consequently, the obvious selective color changes can be exploited for real time and on site applications.