Janus composite nanoparticle-incorporated mixed matrix membranes for CO2 separation

Abstract

Silver-containing Janus nanoparticles were synthesized by adhering silver onto polydopamine nanosphere and then were embedded in Pebax® MH 1657 polymer matrix to fabricate mixed matrix membranes for CO2 capture. The Janus nanoparticle was composed of a polydopamine nanosphere (~80nm) with plenty of catechol-chelated Ag+ ions and a catechol-reduced metallic Ag nanoparticle (~20nm) epitaxially growing from the surface of the polydopamine nanosphere. The highly loaded Ag+ ions (58.41wt% of total Ag content) served as CO2 facilitated transport carriers and thereby endowed the membrane with CO2 facilitated transport ability, and meanwhile the inorganic metallic Ag nanoparticle can interfere the polymer chain packing and optimize the membrane free volume characteristics therefore affecting the diffusion behavior of gas molecules. The membrane separation performance for pure gas (CO2, CH4, and N2) and binary gas mixtures (CO2/CH4 and CO2/N2) of the Janus nanoparticle-incorporated Pebax membrane was investigated and compared with that of the polydopamine nanosphere-incorporated membrane without silver modification. An anti-tradeoff effect was achieved by incorporation of the silver-containing Janus nanoparticles. The best separation performance of the Janus-incorporated Pebax membrane for pure gas was obtained with a CO2 permeability of 150Barrer and a CO2/gas selectivity of 26.3 for CO2/CH4 and 72.5 for CO2/N2, i.e., 83%, 42% and 39% higher than those of neat Pebax membrane, respectively. The results suggested that incorporation of the Janus nanoparticles could achieve both a diffusion tuning effect and a facilitated transport effect simultaneously.