Sulfide sensor based on the room-temperature phosphorescence of ZnO/SiO2 nanocomposite

An environmentally friendly sulfide sensor based on the room-temperature phosphorescence (RTP) of the ZnO/SiO2 nanocomposite has been developed. The ZnO/SiO2 nanocomposite prepared by the sol-gel route produces highly emissive broadband RTP which can be clearly observed by the naked eye. The phosphorescence intensity monitored at 460 nm (excitation at 320 nm) decreases with increasing sulfide ions concentrations. The response behavior of the sensor is dependent on the pH value of the solution. At pH 10, the sensor shows a good, linear response to sulfide from 4.88 x 10(-5) to 1.02 x 10(-2) M with a detection limit of 1.64 x 10(-6) M (3 sigma). It has been successfully applied to the determination of sulfide in spiked water and wastewater. Furthermore, this sensor can be regenerated by dipping it into an H2O2 solution. The mechanisms for the RTP detection of sulfide based on the ZnO/SiO2 nanocomposite and the sensor regeneration by H2O2 are proposed.