Amyloid-like aggregates of bovine serum albumin for extraction of gold from ores and electronic waste

Extracting gold resource from ore and electronic equipment is an important research topic worldwide, because gold has great value in various fields. The existing technology has the disadvantages of high energy consumption, difficult recycling, high cost and poor selectivity. Facing of these challenges, this work underlines the function of amyloid-like protein aggregates as a competitive biological adsorbent for recovering precious metals from low-grade ores and electronic waste. Through the triggering of the rapid amyloid-like aggregation of bovine serum albumin (BSA) via the reduction of its intramolecular disulfide bond, a sandwich-like phase-transited BSA (PTB) membrane is obtained in aqueous solution. The resultant material exhibits gold adsorption capacity per unit area up to -316 mg g-1 m- 2, which is -2100 times higher than those of commonly used industrial adsorbents, such as activated carbon and resins. The material cost of the membrane is 1/12 that of the resin and close to that of activated carbon, and the material also shows advantageous adsorption capacities towards other precious metals, such as Ag, Pd, Pt and Ir. Electrostatic interactions, metal ion chelation and reduction on PTB are the main adsorption mechanisms of this protein-based material. Without any reducing agent, this material can directly reduce adsorbed gold ions to produce gold with a purity of 22 K after pyrolysis. This work underlines a design principle towards cost-effective high-performance biosorbent by manipulating amyloid-like aggregation of proteins to facilitate the exposure of functional groups, which is promising to reduce secondary pollution and meet the targets of circular economy and bioresource reutilization.