Development of ion exchanger by modification of polypropylene fibre waste using radiation–induced graft polymerization of acrylamide and subsequent amination

Abstract

Radiation-induced graft polymerization of acrylamide onto polypropylene fibre waste has been carried out using pre-irradiation technique to develop material with different degrees of grafting. The influence of reaction conditions, such as pre-irradiation dose, monomer concentration, reaction time and ferrous sulfate, on the degree of grafting has also been studied. The addition of ferrous sulfate beyond 0.4% concentration leads to the homopolymer free grafting reaction. The degree of grafting increases with the increase in monomer concentration, reaches maximum at 30% monomer concentration and then decreases with the further increase in the monomer concentration. A continuous increase in the grafting is achieved with the pre-irradiation dose. The replacement of the ferrous sulfate with acetone as an organic solvent causes complete homopolymer inhibition but a much lower graft levels as compared to the ferrous sulfate addition. The grafted fibre is subsequently aminated by Hoffmann degradation method and the fibre with a maximum ion exchange capacity up to 6.2 meq/g for a graft level of 198% is achieved. The modified fibre also shows excellent water uptake which increases as the degree of grafting increases.