Guanidylated hollow fiber membranes based on brominated poly (2,6-dimethyl-1,4-phenylene oxide) (BPPO) for gold sorption from acid solutions.

Novel guanidylated hollow fiber membranes are prepared based on brominated poly (2,6-dimethyl-1,4-phenylene oxide) (BPPO) under mild reaction conditions. 1H-pyrazole-1-carboxamidine hydrochloride (HPCA) is employed for the guanidylation in aqueous solution at room temperature. The obtained guanidylated PPO hollow fiber membranes (GPPO HFMs) contain 0.31-0.95 mmol/g guanidyl groups and show high affinity to tetrachloroauric anions (AuCl(4)(-)) in acid solutions. For 0.1M HCl solution containing 57.8 mg gold/L, the sorption amount can get as high as 130 mg/g. Besides, the GPPO HFMs show preferable selectivity toward gold in multicomponent solution containing Mg(II), Fe(III), Co(II), Ni(II), Cu(II), Zn(II) and Pb(II). A system of comparison experiments involving the sorption behavior of GPPO HFMs and quaternary aminated HFMs are also performed. The results reveal that driving forces for the high adsorption of gold mainly involve complexation mechanism. Overall, the obtained GPPO HFM is a promising chelating material for the recovery of gold.