Biohydrogen purification by membranes: An overview on the operational conditions affecting the performance of non-porous, polymeric and ionic liquid based gas separation membranes

Many types of membranes are available to enrich hydrogen. Nevertheless, there are some with special potential for biohydrogen purification such as the non-porous, polymeric and ionic liquid based membranes. The attractiveness of these membranes comes from the fact that they can be employed nearly under the conditions where biohydrogen formation taking place. Therefore, they appear as promising candidates to be coupled with hydrogen producing bioreactors and hence giving the chance for in situ biohydrogen concentration. It is known that the feasibility and efficiency of membrane technology - beside material selection and module design - significantly depend on the separation circumstances. Thus, the operation of membranes is a key issue and the most important factors to be considered for gas purification are the composition of gas to be separated, the pressure and temperature applied. The scope of this study is to give a comprehensive overview on the recent applications of non-porous, polymeric and ionic liquid supported membranes for biohydrogen recovery, placing emphasis on the operational conditions affecting membrane's behavior and performance. Furthermore, a novel concept for integrated biohydrogen production and purification using gas separation membranes is demonstrated and discussed.