Effect of silica-core gold-shell nanoparticles on the kinetics of biohydrogen production and pollutant hydrogenation via organic acid photofermentation over enhanced near-infrared illumination

A biological photoinduced fermentation process provides an alternative to traditional hydrogen productions. In this study, biohydrogen production was investigated at near IR region coupled to a near-field enhancement by silica-core gold-shell nanoparticles (NPs) over a range of acetate concentrations (5–40 mM) and light intensities (11–160 W/m²). The kinetic data were modeled using modified Monod equations containing light intensity effects. The yields of H₂ and CO₂ produced per acetate were determined as 2.31 mol-H₂/mol-Ac and 0.83 mol-CO₂/mol-Ac and increased to 4.38 mmol-H₂/mmol-Ma and 2.62 mmol-CO₂/mmol-Ma when malate was used. Maximum increases in H₂ and CO₂ productions by 115% and 113% were observed by adding NPs without affecting the bacterial growth rates (6.1–8.2 mg-DCM/L/hour) while the highest hydrogen production rate was determined as 0.81 mmol/L/hour. Model simulations showed that the energy conversion efficiency increased with NPs concentration but decreased with the intensity. Complete hydrogenation application was demonstrated with toxic 2-chlorobiphenyl using Pd catalysts.