Colorimetric Detector for Hydrogen Sulfide Detection in Industrial Environments Based on Silver Nanoparticles Synthesized in Streptomyces Bacteria

Hydrogen sulfide is a colorless, foul-odor pollutant with corrosive properties. This gas is one of the important pollutants released from food factories, fertilizer manufacturing factories, sewage treatment plants, and well drilling. Considering the dangers of being exposed to hydrogen sulfide gas, this article provides a cost-effective, simple, life-saving efficient solution. In this study, Streptomyces bacterium was used for biological production of silver nanoparticles, due to its resistance to the antimicrobial properties of silver. The synthesis and the size range of nanoparticles were confirmed using validation methods. For preparing biocomposite that entraps biological agents, microencapsulation of bacteria was adopted using gellan gum and alginate. In order to validate the final product, the viscosity and porosity of the biocomposite were determined. These tests aimed to investigate the mechanical properties affecting the behaviour and the response time of the final detector. In the end, the detector was exposed to hydrogen sulfide gas, and the color changes of the detector were recorded by time. According to the results, the control sample remained unchanged in all concentrations. However, the color of the test sample, changed faster with the increase in the input gas concentration. Moreover, no color change was observed in concentrations less than 20 mg/l. Therefore, the designed biodetector can be used for qualitative and semi-quantitative measurement of Hydrogen sulfide, in concentrations higher than 20 mg/l.