Nano-coating of ceramic membranes for bubble-free injection of CO2

•Ceramic membranes were changed into hydrophobic gas/liquid contactors.•These membranes were tested for effective and complete CO2 injection.•Bubble-free dissolution of CO2 was demonstrated for all membranes.•Nano-coated hydrophobic membranes displayed a 10 times higher dissolution rate.

Do be competitive toward sugar-based heterotrophic culture of microalgae, CO2-based autotrophic (photosynthesis) culture, which offers the asset of contributing to CO2 capture, must ensure that providing the main nutriment, that is, CO2 does not create a bottleneck in biomass production. Besides, the addition of gas by a bubbling system, cannot be selected for large scale application as most of the CO2, initially captured, will be released back to the atmosphere as a result of the poor dissolution rate. The optimized and controlled injection of CO2 is a major milestone on the route to develop effective industrial closed photobioreactors. We report in the present study how a commercial tubular hydrophilic ceramic membrane can be turned into an efficient hydrophobic gas/liquid contactor, for an optimized and bubble-less dissolution of CO2. Moreover, the additional coating of nanoparticles allowed us to improve the dissolution rate of CO2 into water, a very important parameter for the efficient culture of microalgae, by a factor 10, compared with the uncoated hydrophobic membrane, tested at the same CO2 flow rate.

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