Adsorption properties of novel chelating resins containing 2‐amino‐5‐methylthio‐1,3,4‐thiadizole and hydrophilic spacer arms for Hg²⁺ and Ag⁺

Abstract

The adsorption properties, including the adsorption kinetics, adsorption isotherms, and adsorption selectivity, of newly formed chelating resins that contained a heterocyclic functional group and a hydrophilic spacer arm of poly(ethylene glycol) [polystyrene-diethylene glycol-2-amino-5-methylthio-1,3,4-thiadizole (PS-DEG-AMTZ) and polystyrene-triethylene glycol-2-amino-5methylthio-1,3,4-thiadizole (PS-TEG-AMTZ)] were studied in detail. The results show that the adsorption kinetics of PS-DEG-AMTZ and PS-TEG-AMTZ for Hg 2þ and Ag þ could be described by a pseudo-second-order rate equation. The introduction of a spacer arm between the polymeric matrix and functional group was beneficial for increasing the adsorption rates. The apparent activation energies of the resins for Hg 2þ and Ag þ were within 20.89-32.32 kJ/mol. The Langmuir model could describe the isothermal process of Hg 2þ and Ag þ . The competitive adsorption of the resins for Hg 2þ and Ag þ in binary mixture systems was also investigated. The results show that Hg 2þ and Ag þ were adsorbed before the other metal ions, such as Cu 2þ , Zn 2þ , Fe 3þ , Cd 2þ , and Pb 2þ , under competitive conditions. Five adsorption-desorption cycles were conducted for the reuse of the resins. The results indicate that these two resins were suitable for reuse without considerable changes in the adsorption capacity.

Adsorption of Silver(I) from Aqueous Solution by Chelating Resins with 3-Aminopyridine and Hydrophilic Spacer Arms: Equilibrium, Kinetic, Thermodynamic, and Mechanism Studies

“…In general, the adsorption selectivity of chelating resins has been reported to be dependent mainly on the chelate forming properties of functional groups chemically bonded on supports such as silica gel, cellulose, and macroporous copolymers. Thus, the functional groups play an important role in the adsorption capacity, effectiveness, and selectivity of the chelating resins. − Recently, it has been proved that chelating resins containing heterocyclic functional groups such as pyridine, imidazole, thiazole, and so forth possess excellent adsorption and selectivity properties for metal ions, especially for noble metal ions. − Among the above-mentioned heterocyclic functional groups, aminopyridine is one of the common functional groups used to prepare chelating resins. , …”