Recovery of silver ions from aqueous solutions by thiourea- and urea-formaldehyde chelating resins

In the present work, thiourea-formaldehyde and urea-formaldehyde chelating resins were synthesized and they were used in the recovery of Ag+ ions in the aqueous solution containing Cu2+ and Zn2+ ions.In the batch method studies with TF resin, the optimum pH of the initial solution for Ag+ adsorption was determined as pH=3 and Ag+ adsorption capacity of the resin was calculated as 58.14 mg Ag+/g. On the other hand, the optimum pH was 2 and Ag+ adsorption capacity was 47.39 mg Ag+/g with UF resin.Moreover the recovery and separation of Ag+ ions from Cu2+ and Zn2+ were examined by column method. In the column studies with TF, the adsorption capacities were found as 36.2 mg Ag+/g, 0.8 mg Cu2+/g and 0.07 mg Zn2+/g. On the other hand, the adsorption capacity with UF were 33.6 mg Ag+/g, 0.121 mg Cu2+ and 0.002 mg Zn2+/g. It was seen that Ag+ ions could be separated and recovered. More effectively from Cu2+and Zn2+ ions when TF resins were used. In addition, the reusage of the resin was examined and it was seen that the resins were reusable.Keywords: Thiourea-formaldehyde, Urea-formaldehyde, Chelating resin, Silver(I) ions, Adsorption, Recovery