Sorption of silver (I) ions from aqueous solutions using the synthetic sorbent

We study the sorption of silver ions from aqueous solutions by a synthetic chelating sorbent. In the presence of formaldehyde, a polymeric sorbent based on a copolymer of styrene with maleic anhydride, modified with N,N’-diphenylguanidine, was synthesized and further used for extracting Ag(I) ions. The composition and structure of the synthesized polymeric chelating sorbent were studied using IR and UV spectroscopy methods. A simple, inexpensive, and efficient method for extracting Ag(I) ions from aqueous solutions was used. The effect of various parameters on the sorption process was studied, including the acidity of the medium (pH), the initial concentration of the metal ion, the time required to establish complete sorption equilibrium, and ionic strength. The optimum pH value for the extraction of Ag(I) was found to be 6. The process is characterized by a high adsorption capacity reaching 547.2 mg/g. The research results showed that the time required to establish a complete sorption equilibrium for the sorbent modified with N,N’- diphenylguanidine is 60 min. Ag(I) adsorption increases up to the value of ionic strength of μ = 1, after which its intensity decreases. At the final stage, the process of desorption of absorbed silver ions was carried out. During desorption, the best eluting agent for the extraction of Ag(I) was determined to be 0.5 M HNO3. The sorbent can be re-used after regeneration. The copolymer of styrene and maleic anhydride modified with N,N’-diphenylguanidine has a high sorption capacity and, therefore, can be used as a potential adsorbent for the extraction of silver (I) from aqueous solutions.