Aminophosphonic acid derivatized polyacrylonitrile fiber for rapid adsorption of Au(S2O3)23– from thiosulfate solution

Abstract

A fast and efficient Au (I) recovery adsorption method from an actual leaching solution of Cu2+-en-S2O32- is presented. Aminophosphonic acid derivatized polyacrylonitrile fibers (PAN-NP), prepared with triethylenetetramine and phosphoric acid by chemical grafting, were used as the adsorbent. The adsorbent was well characterized by FT-IR, SEM, TGA and XPS. The effects of contact time, pH, temperature, and Au (Ⅰ) concentration were also investigated. PAN-NP can rapidly capture Au(S2O3)23– (20 min) and has a maximum adsorption capacity of 14.68 kg/t. Compared with -SH modified, PAN-NP has better stability and without oxidized. The adsorption process was described based on the Langmuir isothermal model (R2 > 0.99). Thermodynamic parameters indicated that the adsorption of Au(S2O3)23– on PAN-NP was exothermic (ΔHθ = −9.906 kJ/mol) and adsorption mechanism involved a collective effect resulting the anion exchange of Au(S2O3)23– with –RNH3+H2PO3-, electrostatic attraction between –RNH3+ and Au(S2O3)23– and complexation of P = O with Au (Ⅰ). Besides, PAN-NP-Au can be effectively eluted by sodium sulfite. Importantly, in the Cu2+-en-S2O32- actual leaching solution, the PAN-NP can efficiently recover Au (I) with an adsorption percentage of up to 97 % at a the solid­liquid ratio of 1:50, thereby affording a satisfactory application result. This is a meaningful method for recovering Au (Ⅰ) from thiosulfate solution.

Keywords

• Polyacrylonitrile fibre
• Gold thiosulfate complex
• Recovery
• Chemical grafting