Mesoporous TiO<inf>2</inf> nanoparticles for silver recovery from cyanide-contaminated plating effluent: One-pot synthesis and application of used TiO<inf>2</inf>

Abstract

Mesoporous TiO2 nanoparticles was one-pot synthesized by microwave-assisted hydrothermal without any solvents or dispersing agents. It was found that high microwave power produced highly crystalline TiO2 NPs with a high content of anatase phase and BET surface area. A higher number of microwave-treated cycles also resulted in highly crystalline TiO2 NPs, but with lower anatase phase content and BET surface area. Among various TiO2 NPs samples, the TM8_3 synthesized at 800 W with three microwave-treated cycle exhibited the highest photocatalytic silver recovery even at the third use. At optimum condition (e.g. 25 vol.% C2H5OH, 0.05 mM Na2S2O3, 1.0 g/L), approximately 95% of silver was recovered within 30 min. Additionally, the recovered metallic silver was found to decorate on the surface of TM8_3 as Ag/TM8_3 NPs, demonstrating superior optical properties and photocatalytic activity for simultaneous H2 production and color reduction in wastewater from an ethanol production plant under UV light irradiation.