Adsorption of silver from aqueous solution with high capacity and selectively by using Ag(I) imprinted polymeric nanoadsorbent

Abstract

Abstract The selective separation of precious metals from complex wastewater is important issue in terms of protecting the environment, aquatic ecosystems, water resources, and recycling of resources. Silver, which has been used for years in many fields from industry to health, enters the food chain and accumulates in living organisms by forming stable complexes, usually with sulfur containing molecules such as cysteine. In this study, cysteine-containing polymeric nanoparticles were synthesized by miniemulsion polymerization method by mimicking biological systems based on the affinity of silver to cysteine. The synthesized silver ion imprinted (Ag+-IIP) poly(Hydroxyethylmethacrylate-N-methacryloyl-L-cysteine) poly(HEMA-MAC) nanoparticles were characterized by Elemental analysiz zeta sizer AFM, SEM, FTIR. With elemental analysis study, the cysteine content of polymeric nanoparticles was determined to be 7.3 mmol MAC/g polymer. Molecular imprinting (MIP) technique was used to increase the selectivity of synthesized nanoparticles to Ag+ ions. The effects of pH, ionic strength and interaction time on the adsorption of Ag+ ions were investigated. To the experimental studies, the highest adsorption amount (196.9 mg/g nanoparticle) was reached in a short time like 40 minutes at pH:5 and 150mg/L concentration. Selectivity studies of synthesized Ag+-IIP nanoparticles to Ag+ ions were carried out in the presence of Li+, Ba2+, Hg2+ and Cd2+ ions, and it was observed that the nanoparticles adsorbed Ag+ ions with high selectivity. Ag+-IIP nanoparticles have 3.7, 3.1, 2.4 and 2.6 times more selective or higher affinity for Ag+ ions compared to Li+, Ba2+, Hg2+ and Cd2+ ions, respectively, than Ag+-non-imprinted (NIP) nanoparticles. The reusability studies, showed that there was no significant decrease in the adsorption capacity of the nanoparticles after the adsorption-desorption process repeated 10 times.