Hollow fiber membrane contactor based CO₂ absorption-stripping using novel solvents and membranes

Nondispersive absorption of CO₂ into an aqueous solution of a volatile amine and its subsequent regeneration by stripping in porous hydrophobic hollow fiber devices have encountered a number of issues: membrane pore wetting reducing CO₂ transfer rates; loss of volatile absorbents. These issues have been addressed here using novel nonvolatile absorbents and novel hollow fiber membranes. Continuous CO₂ absorption-stripping was carried out for 55 days using a novel absorbent, polyamidoamine (PAMAM) dendrimer of generation 0, in an aqueous solution using conventional Celgard polypropylene (PP) hollow fibers in an absorber followed by a stripper to successfully resolve the issue of pore wetting. This nonvolatile amine PAMAM provides a novel dimension to CO₂ scrubbing using conventional porous PP membrane contactors. Elimination of pore wetting and reduction of loss of the volatile monoethanolamine (MEA) from an aqueous solution was studied for an extended period of more than 55 days using an absorber and a stripper made out of porous poly(4-methyl-1-pentene) (PMP) hollow fibers having an ultrathin dense skin. The dense PMP fiber skin could not eliminate completely the loss of MEA. The PMP membrane resistance was an important factor in CO₂ absorption along with the MEA concentration.