Metal chelates with some cellulose derivatives; part IV. Structural chemistry of HEC complexes

Cellulose-based anion exchanger with tertiary amine functionality for the extraction of arsenic(V) from aqueous media

“…Grafting of synthetic polymers onto solids followed by functionalization is a well-known method for the modification of the physical and chemical properties of the adsorbent and to improve the adsorption capacity (Hegazy et al, 2001). Various cellulose derivatives have been used as ion exchangers or chelate resins because of their high chemical and mechanical stability and hydrophilic character (Guclu et al, 2003;Basla et al, 1996). The substitution of tertiary and quaternary ammonium functional groups on cellulose backbone increases the number and changes the nature of reaction sites capable of adsorbing certain metal ions in solution (Simkovic et al, 1992;Kawamura et al, 1993).…”

Characterization of Polymer Complexes by Thermal and Ir Spectral Analyses

“…0.67 and 1.5, respectively, were used as ligands, as in previous work (12)(13)(14)(15)(16). Carboxymethyl cellulose (CMC) and hydroxyethyl cellulose (HEC) of degree of substitution (D.S.)…”

“…As in the case of CMC-metal complexes, the degree of covalency in the metal-ligand-bond plays an important role in improving the thermal stability of HEC, whereas HEC-Ni(II) and HEC-Fe(III) complexes have higher ∑ E a than other complexes. The binding sites in the case of the HEC-Cr(III) complex are the ether oxygen between two ethoxyl groups and the oxygen of OH in the hydroxylethyl groups, but through the oxygen of the ethoxyl group and the 1-ary O atom of the glycopyranose ring substituted by the hydroxyethyl group, in the case of HEC-Co(II) complex, as illustrated in Scheme I (15). Table 2 also shows clearly that the relatively higher electronegativity of metal cation plays an important effect in improving the thermal stability of the HEC-Co(II) complex than the HEC-Cr(III) complex, despite both of them having the same molecular formula (Table 3).…”

“…Infrared spectroscopy cannot be used to elucidate fully the structure of the complex, but it can give some useful information about the functional groups of the ligand chelated with the metal ion, as described in our previous work (12)(13)(14)(15)(16).…”