Effectiveness of CO2 - Sorbent Coated Membrane for Improving Dark Fermentative Hydrogen Production

Dark fermentative hydrogen production (bioH2) could be greatly impaired by the build-up of bioH2 in the reactor headspace, as well as, its re-dissolution in the culture medium. This is because carbon dioxide (CO2) and reduced nicotinamide adenine dinucleotide in the medium could be used for succinate and fumarate production, which could impact negatively on the bioH2 production. Hence, prompt removal of headspace CO2 could prevent its re-dissolution in the culture medium and thereby creating potential for improved bioH2 yields. Therefore, this study investigated the bioH2 production effect of removing CO2 in the reactor headspace using calcium oxide (CaO) sorbent. The results showed that reactors with membrane impregnated with 1 M CaO produced 15.6% and 11.6 % hydrogen yields higher than non-impregnated membranes, and membranes impregnated with 2 M CaO, respectively. Besides, CO2 yield and loss in membrane storage modulus of 74.5 ml/ g VS and 40 %, respectively, were measured for reactors with 1 M CaO-impregnated membranes while CO2 yield and loss in membrane storage modulus of 79.9ml/ g VS and 28%, respectively, were measured for reactors with 2 M CaO-impregnated membranes. The results indicated that 1 M CaO-impregnated membranes were more efficient for CO2 adsorption than 2 M CaO-impregnated membranes. The improved yield using CaO-impregnated membranes justified the effectiveness of the membrane for headspace CO2 capture and the possible commercial application of the technique if improved upon. The research findings could contribute to the development of hydrogen energy technology.