Removal of heavy metals in industrial wastewaters by ion-exchanger grafted textiles

A special class of grafted textiles was studied in order to remove heavy metals from industrial wastewaters. Three cation-exchanger textiles (CET) were tested in a batch reactor, each carrying carboxylate (R---COO-, Na+), sulfonate (R---SO3-, Na+) or phosphate (R---O--PO32-, 2Na+) functional groups. The study of their behaviour towards Cu(II) and Cd(II) was carried out as a function of time (exchange kinetics) and at equilibrium with increasing metal concentrations (exchange isotherms). After determining the exchange capacities and selectivity coefficients of CET, the influence of different parameters (the counter-ion and functional group nature, the metal concentration, the presence of different competitors in the solution) on the removal of Cu(II) and Cd(II) was shown. The optimal use conditions of CET were therefore well defined and compared with those of conventional resins. Finally, desorption studies were performed with various regenerating solutions in order to determine the best conditions for textile regeneration and an optimal heavy metal concentration. These cation-exchanger textiles offer an interesting alternative for water treatment by ion-exchange technique.