Remoção de CO2 de ambientes confinados utilizando contactores com membranas e água do mar sintética como absorvente

Abstract

This work evaluated the CO2 removal process of a CO2/N2 (10/90% v/v) mixture using membrane contactors and synthetic sea water as absorbent (3.5% NaCl, pH 8). A commercial module containing polypropylene (PP) hollow fibers was used verify that the absorbent flow is the variable process that most influences the CO2 flux. Polyvinylidene fluoride (PVDF) hollow fibers were synthesized using the phase inversion process by immersion-precipitation. Characterization tests revealed that the outer surface nanopores of the fibers are in the range of 10 to 40 nm. The porosity was twice as high as that of the commercial PP hollow fibers, whose porosity was 30%. Helium ion microscopy was used as an additional tool in order to characterize PVDF hollow fibers morphology. By using this technique it was possible to clearly observe hollow fiber morfology, without the need of sputtering polymeric membrane samples. The presence of nanopores on the outer surface of the PVDF hollow fibers helps prevent wetting, which prevents the decrease in process performance. Nanopores were obtained by choosing the synthesis conditions that can be manipulated by Nanotechnology Engineering. Gas-liquid contactor tests were carried out with both PVDF and PP hollow fibers. In-house hollow fibers presented CO2 flux 2.5 times higher than the comercial. A mathematical model, that was validated with commercial module experimental data, provides a satisfactory prediction of CO2 flux behavior concerning the process variables and emphasizes that the absorbent flow is the variable that most influences the process. In addition, the CO2 removal process was applied and validated for confined environments by using computer simulation.