Synthesis of novel sulfydryl-functionalized chelating adsorbent and its application for selective adsorption of Ag(I) under high acid

Abstract

• A novel sulfydryl-functionalized chelating adsorbent is synthesized by radiation grafting using stable polypropylene non-woven fabrics. • The adsorbent contains two functional groups, amine and sulfhydryl. • The adsorbent has two adsorption mechanisms for silver(Ⅰ) under high acid: ion exchange and chelate adsorption. The sulfhydryl has an excellent chelating affinity towards silver(Ⅰ) and the protonated amine adsorbs [Ag(NO 3 ) 2 ] −1 by ion exchange. • Silver(Ⅰ) is effectively and selectively adsorbed in high acid environment. A novel sulfydryl-functionalized adsorbent PP-g-GMA@MEA for recovery of Ag(I) was synthesized by γ-ray induced simultaneous grafting of glycidyl methacrylate (GMA) onto polypropylene (PP) non-woven fabric, followed by ring-opening processes with mercaptoethylamine (MEA). The obtained adsorbents before and after adsorption of Ag(I) were fully characterized by SEM, EDS, FT-IR spectra, XRD and XPS. Batch adsorption experiments were carried out to evaluate adsorption abilities of the adsorbents under high acidity. The adsorption kinetics of Ag(I) were well fitted with pseudo-second-order kinetics model. The maximum adsorption capacity calculated by the Langmuir isotherm model was 262.51 mg/g at 25 °C. EDS, XRD and XPS analyses confirmed the mechanism of adsorption under high acidity was chelating reaction between -SH and Ag(I) and ion exchange adsorption towards [Ag(NO 3 ) 2 ] −1 . Through competitive adsorption tests, the PP-g-GMA@MEA was found remarkably selective towards Ag(I) when it coexisted with Cu(II), Co(II), Ni(II) and Cr(III) in high acidity medium. Therefore, the developed PP-g-GMA@MEA composite would be a promising adsorbent for Ag(I) recovery from industrial effluents.