Bacterial-driven upcycling spent Ag into high-performance catalyst for toxic organics reduction

Achieving up-cycling and reusing of silver from the waste X-rays films is currently a huge challenge. Here, we designed a facile method that upcycles Ag⁺ extract efficiently from waste film into highly dispersed value-added biological Ag/AgO-AgCl nanoparticles (bio-Ag/AgO-AgCl NPs) using Bacillus thuringiensis-secreted extracellular polymeric substance without additional reductants and electron donors. The recovery efficiency of silver exceeded 99.8%. Surprisingly, the bio-Ag/AgO-AgCl NPs can well solve the bottleneck problem of slow Ag catalytic kinetics. When the amount of catalyst was 1.9 mg, the reduction efficiency and reduction rate of 10 ppm methyl orange were 97.9% and 7 min, and that of 30 ppm Congo red were 95.3% and 5 min respectively, which is superior to other chemically synthesized silver-base catalysts. This bioremediation methodology provides an effective and practical technical approach for precious metal remediation and sustainable energy development.