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

A fast and efficient Au (I) recovery adsorption method from an actual leaching solution of Cu 2+ -en-S 2 O 3 2- 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(S 2 O 3 ) 2 3– (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 ( R 2  > 0.99). Thermodynamic parameters indicated that the adsorption of Au(S 2 O 3 ) 2 3– on PAN-NP was exothermic ( ΔH θ  = −9.906 kJ/mol) and adsorption mechanism involved a collective effect resulting the anion exchange of Au(S 2 O 3 ) 2 3– with –RNH 3 + H 2 PO 3 - , electrostatic attraction between –RNH 3 + and Au(S 2 O 3 ) 2 3– and complexation of P = O with Au (Ⅰ). Besides, PAN-NP-Au can be effectively eluted by sodium sulfite. Importantly, in the Cu 2+ -en-S 2 O 3 2- 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.