Chelating resins. V: Synthesis and characterization of chelating resins of formaldehyde‐condensed phenolic Schiff bases derived from 4,4′‐diaminodiphenyl sulphone with hydroxy benzaldehydes

Abstract

The synthesis and characterization of a number of chelating resins having multiple functional groups capable of coordination to several metal ions is reported. The resins were synthesized by condensing Schiff bases derived from 4,4'-diaminodiphenyl sulphone and hydroxy benzaldehydes with formaldehyde and furfuraldehyde. The resins formed a number of polychelates with metal ions like Cu(II) and Ni(II). The Schiff bases, resins and the polychelates were characterized by IR, UV-vis., 1 H nuclear magnetic resonance spectra and thermogravimetric analysis. From the spectral data the possible coordination sites of the resins towards the metal ions were determined. The intrinsic viscosity of the resins was determined by viscometry in dimethylsulphoxide. The adsorption characteristics of the resins towards metal ions in dilute aqueous solutions were measured. The structure and the molecular geometry of the resins was observed to strongly influence the metal uptake behaviour, in addition to the influence of pH, temperature, particle size and metal ion concentration. Metallization of the resins significantly affected the thermal stability; the polychelates were found to be less stable than the resins.