Synthesis, characterization, and metal-ion uptake studies of chelating resins derived from formaldehyde-condensed azodyes of aniline and 4,4?-diaminodiphenylmethane coupled with phenol/resorcinol

The diazonium salts of aniline and 4,4'-diaminodiphenylmethane coupled with phenol and resorcinol were condensed with formaldehyde in alkaline media to yield polymeric resins. These polymers were found to readily react with metal ions like Cu2+ and UO22+, forming polychelates. The azodyes, resins, and polychelates were characterized by several instrumental techniques such as elemental analysis, FTIR, H-1-NMR, GPC, XRD, TG-DTG, and DSC studies. The chelating capacity of the resins toward Cu2+ and UO22+ ions was studied by spectrophotometry. The extent of metal loading of the resins was studied by varying the time of contact, metal-ion concentration, and pH of the reaction medium. The alkali and alkaline earth metal ions had little effect on the metal-ion uptake behavior of the resins. The resin derived from the azodye of 4,4'-diaminodiphenylmethane was found to be more efficient in removing the metal ions from solution than were the resins from aniline. The optimum conditions for effective separation of Cu2+ from UO22+ were determined. (C) 2000 John Wiley & Sons, Inc.