Recovery of gold through adsorption onto sericin and alginate particles chemically crosslinked by proanthocyanidins

The recovery of gold from wastewater has been encouraged in the last years due to this metal high cost, elevated demand, and low availability. Sericin and alginate particles chemically crosslinked by proanthocyanidins (SAPAS) were successfully used in this study for this purpose. The maximum adsorption capacity predicted by the Dubinin-Radushkevich model was 237.60 mg/g at 303 K. The thermodynamic parameters revealed that the process is spontaneous, endothermic and also governed by entropic changes. The characterization of SAPAS before and after gold adsorption (SAPAS-Gold) suggested that the uptake of this metal involves ion exchange and subsequent reduction. The thermogravimetric analysis showed that elemental gold may be recovered from SAPAS surface by the incineration process. Alternatively, both the reuse of SAPAS and the efficient recovery of gold (84.389 ± 2.103%) is possible by employing the desorption process with thiourea (0.5M)/hydrochloric acid (2M) solution. •Gold uptake involved the adsorption-reduction mechanism.•Gold uptake process was spontaneous and endothermic.•A maximum adsorption capacity of 237.60 mg/g was obtained at 303 K.•A gold recovery of 84.4% was achieved using thiourea in acidic medium as eluent.•Incineration may be used to recover zero-valent gold from the adsorbent surface.