Со(ІІ) and Ni(II) Removal from Aqueous Solutions by Polymer and Polymer/Silica Adsorbents with Sulfo and Carboxyl groups

Sulfo and carboxyl group-containing polymers and polymer/silica adsorbents poly(acrylonitrile-co-2-acrylamido-2-methylpropane-1-sulfonic acid-co-acrylic acid-co-N,N’-methylene-bis-acrylamide) [poly(AN-co-AMPS-co-AAco-MBA)] and poly(AN-co-AMPS-co-AA-co-MBA)/SiO2 were synthesized by a UV-initiated polymerization or simultaneous UV-initiated polymerization and in situ sol-gel process and used as adsorbents for removal of Co(II) and Ni(II) ions from aqueous solutions. The adsorption capacity and the effect of the pH in the removal process have been studied. The poly(AN-co-AMPS-co-AA-co-MBA) adsorbent exhibited high efficiency: up to 91.8 % removal of Co(II) and 89.7 % removal of Ni(II). Polymer/silica adsorbents showed higher removal capacity as compared to pure polymer. The adsorption kinetics of Co(II) and Ni(II) ions were found to be satisfactorily described by the pseudo-second-order reaction equation of the Lagergren kinetic model, suggesting the ion-exchange nature of the process.