Membranas hidrofóbicas para a remoção de CO2 em espaços confinados utilizando contactores gás-líquido

Abstract

This dissertation developed hydrophobic microporous composite membranes, intended for CO2 removal using gas-liquid contactors in confined spaces. To enhance the membrane surface hydrophobicity, the spray coating technique was employed, utilizing silica nanoparticles (SiNP) and polydimethylsiloxane (PDMS). SiNP formed a thin layer with PDMS, creating micro-nano hierarchical structures that increased the surface roughness and consequently its hydrophobicity. The membranes were evaluated for morphology, hydrophobicity, permeability, and CO2 removal flux in gas-liquid absorption using a 0.01M NaOH solution as the absorbing liquid. Correlations were established between the SiNP-PDMS dispersion and the number of coatings, resulting in increased hydrophobicity, enhanced liquid entry pressure (LEP) and reduced permeability. After coating, the commercial membrane exhibited improvements in contact angle, from 130.6° to 149.5°, and LEP, from 3 to 4 bar, with a decrease in permeated CO2 flux from 2.51 x 10-2 mol m-2 s-1 to 1.05 x 10-2 mol m-2 s-1. The initially hydrophilic PVDF support, with a surface angle of 64.4°, showed an increase to 149° after coating, along with a rise in LEP from 1 to 5 bar, enabling a CO2 removal performance of 1.57 x 10-2 mol m-2 s-1. Considering the increases in contact angle and LEP, as well as the observation that membrane contactor technology experiences reduced CO2 removal efficiency over time due to pore wetting, the membranes developed in this study demonstrate promise for long-term applications and CO2 removal in confined environments.