High CO2 separation performance of Pebax®/CNTs/GTA mixed matrix membranes

Pebax®/CNTs (MWNTs, MWNTs-OH and MWNTs-NH2) and Pebax®/MWNTs-NH2/GTA mixed matrix membranes (MMMs) were prepared with solution-casting method. First, the effect of CNTs functionalization on the properties of Pebax®/CNTs MMMs was studied. The functionalization of CNTs promoted their dispersion in Pebax® matrix. The gas permeabilities of Pebax®/CNTs MMMs were enhanced with the addition of CNTs. And, the enhancement of gas permeabilities induced by CNTs was in the order of MWNTs-NH2>MWNTs-OH>MWNTs. Then, Pebax®/MWNTs-NH2 MMMs were chosen to be further modified with GTA. GTA promoted the dispersion of MWNTs-NH2 in Pebax® matrix, and it acted as a plasticizer and increased the chain mobility of Pebax® as well as the FFV of Pebax®/MWNTs-NH2/GTA MMMs. The gas diffusion coefficients and solubility coefficients all increased with the increase of GTA content. Consequently, the gas permeabilities of Pebax®/MWNTs-NH2/GTA MMMs remarkably increased with the increase of GTA content. CO2 permeabililty of P10CN1G25 was higher than pristine Pebax® and P10CN1G0 by almost ten times and six times, respectively. CO2/light gas separation performance of Pebax® was significantly enhanced by CNTs and GTA.