Fabrication of MWCNTs/PDMS mixed matrix membranes for recovery of volatile aromatic compounds from brewed black tea

A novel multiwall carbon nanotube (MWCNTs)/polydimethylsiloxane (PDMS) mixed matrix pervaporation membrane with a dipping amount of 2% was successfully fabricated and characterized. The presence of MWCNTs provided two more transport channels in PV process, greatly improving the separation performance of the membrane for aromatic compounds. The maximum permeation fluxes in MWCNTs/PDMS of methyl salicylate (MetSa), linalool and β-Ionone were1.25, 1.28 and 0.075 g·m⁻²·h⁻¹, respectively, at 30 °C in an aromatic-aqueous model system, which were 19.04%, 23.07% and 50% higher than those in a pure PDMS membrane. The pervaporation of MetSa and linalool was improved by the presence of β-Ionone; however, that of MetSa was competitively weakened by linalool. Furthermore, the performance of MWCNTs/PDMS for recovery of VOCs from real brewed tea was investigated. The recovery rates of linalool, MetSa and β-Ionone were 85.80%, 90.84% and 83.40%, after treatment at 30 °C for 6 h, and the concentrations on the permeation side were as high as 3.53 mg·L⁻¹, 4.47 mg·L⁻¹ and 72.41 mg·L⁻¹, which showed good application prospects of MWCNTs/PDMS membrane in aroma recovery by pervaporation technology.