Bio-hydrogen production of anaerobic bacteria in reverse micellar media

Biohydrogen production using anaerobic mixed bacteria in dioctyl sulfosuccinate sodium salt (AOT)/isooctane/water reverse micelles has been investigated. It was found that hydrogen production was enhanced by optimizing some relevant parameters, such as surfactant concentration, water content (w0), initial pH, temperature, and substrate concentration. The maximum hydrogen productivity was obtained as 3.51 mol H2/mol glucose, which was 2.28-fold in aqueous solutions. Analysis of volatile fatty acid suggested that variation of AOT concentration resulted in a dominated metabolic alteration of microorganisms, whereas the dominated acetic acid products were always found at a wide range of water content (w0), which was much different with the dominated butyric acid products in aqueous phase. Peak value of hydrogen productivity occurred at initial pH 7.5 in aqueous solutions in contrast that hydrogen production kept stable at pH range from 7.0 to 8.5 in reverse micellar systems. Temperatures of 30–35 °C were optimum for hydrogen production both in aqueous phase and reverse micellar systems. Organic substrates such as glucose, sucrose and starch, were found with similar behaviors that increasing substrate concentration (>11.1 g/l) had no apparent enhancement for hydrogen production in reverse micellar systems.