Abdul Qader

Membrane Gas-Solvent Contactor Pilot Plant Trials of CO2 Absorption from Flue Gas

Membrane gas-solvent contactors have received much attention for CO2 absorption, as the approach incorporates advantages from both solvent absorption and membrane gas separation. This study reports on pilot plant trials of three membrane contactors for the separation of CO2 from flue gas. The contactors were porous polypropylene (PP), porous polytetrafluoroethylene (PTFE), and non-porous polydimethylsiloxane (PDMS), with the solvent PuraTreatTM FTM. To enable performance comparison, laboratory measurements based on a gas mixture of 10% CO2 in N2 were also undertaken on the same contactor–solvent systems. It was found that the PP contactor experienced significant pore wetting in both laboratory and pilot plant studies. In contrast, the PTFE contactor experienced only minor pore wetting in the laboratory. However, in the pilot plant trial of the PTFE contactor extensive pore wetting was observed, and the overall mass transfer coefficient measured was comparable with the PP contactor. The non-porous PDMS contactor had an overall mass transfer coefficient two orders of magnitude less than the PP contactor, due to the greater mass transfer resistance of the polymeric film. However, the non-porous membrane does not experience pore wetting, which resulted in the overall mass transfer coefficient being similar for both laboratory and pilot plant measurements.

Interfacial Kinetics of the Stripping of Acetic and Citric Acids from Tri-n-octylamine Complexes

Abstract A rotating diffusion cell (RDC) was used to measure the kinetics of acetic and citric acids stripping from an organic solvent phase to water. It has been proved that the carboxylic acid transfer is rate controlled by a diffusion process. The rate constant for acetic acid was found to be (3.43 ± 0.18) × 10−5 m·s−1 at 298 ± 0.1 K. For citric acid, the rate constant determined as a function of temperature was k = (0.043 ± 0.002)e −3680/T for which the activation energy is 30.6 ± 1.0 kJ-mol−1. The stripping resistance depends on the number of carboxylic acid groups in the acid and is largely entropic in nature.