A novel fiber‐coated strong base‐type anion exchanger with superfast kinetics. Removal and recovery of silver thiosulfate from aqueous solutions

Abstract

ABSTRACT:A commercial acrylic fiber with 92% (w/w) acrylonitrile content was partially hydrolyzed converting a fraction of the nitrile (OCN) groups to carboxylic acid (OCOOH) groups, to coat the fiber with polyethylenimine (PEI) resin, which was then crosslinked with glutaraldehyde and further quaternized with ethyl chloroacetate to produce a novel strong-base anionic exchanger in the form of fiber. Designated as PAN(QPEI.XG)(Cl Ϫ ), the fibrous sorbent was compared with a commercial bead-form resin Amberlite IRA-458(Cl Ϫ ) in respect of sorption capacity, selectivity, and kinetics for removal of silver thiosulfate complexes from aqueous solutions. Though the saturation level of [Ag(S 2 O 3 ) 2 ] 3Ϫ on PAN(QPEI.XG)(Cl Ϫ ) is considerably less than that on IRA-458(Cl Ϫ ), the gel-coated fibrous sorbent exhibits, as compared to the bead-form sorbent, a significantly higher sorption selectivity for the silver thiosulfate complex in the presence of excess of other anions such as S 2 O 3 2Ϫ , SO 4 2Ϫ , and Cl Ϫ , and a remarkably faster rate of both sorption and stripping. The initial uptake of the sorbate by the fibrous sorbent is nearly instantaneous, reaching up to ϳ80% of the saturation capacity within 10 s, as compared to only ϳ12% on the bead-form sorbent. The high initial rate of uptake fits a shell-core kinetic model for sorption on fiber of cylindrical geometry. With 4M HCl, the stripping of the sorbed silver complex from the fibrous sorbent is clean and nearly instantaneous, while, in contrast, a much slower rate of stripping on the bead-form sorbent leads to its fouling due to a slow decomposition of the silver thiosulfate complex in the acidic medium.

2-Mercaptobenzimidazole derivative of chitosan for silver sorption – Contribution of magnetite incorporation and sonication effects on enhanced metal recovery

“…In the case of thiosulfate leachates, silver was efficiently recovered using quaternary ammonium based-sorbents (quaternary PEI/PAN, and Amberlite IRA-458 resin) [16]. Phosphorus-based resins were also reported as promising sorbents for Ag(I) in nitric acid solutions.…”