Preparation And Gas Separation Performance Of Nano-sized Carbon@Carbon Hybirds-Polymer Mixed Matrix Membranes

With the rapid development of the process of industrialization,the increasing atmospheric CO₂ concentration has caused a series of natural disaster and environmental pollution recently.Meanwhile,CO₂ is a potential energy in agricultural and industrial fields.Thus,how to effectively separate and capture CO₂ is one of main scientific problems that people are facing and one of important research topics for researchers.In this work,core/shell structured multi-walled carbon nanotube@graphene oxide nanoribbons?MWCNT@GONRs?nanohybrids were successfully prepared using a modified chemical longitudinal unzipping method.Subsequently,MWCNT@GONRs nanohybrids were used as fillers to enhance the gas separation performance of mixed matrix membranes?MMMs?.Firstly,we prepared MWCNT@GONRs-polyimide?PI?MMMs and studied their gas separation performance.The results showed that the MWCNT@GONRs-PI MMM possessed the most excellent gas separation performance when the content of MWCNT@GONRs was 1%.And the selectivity of CO₂/N₂ and CO₂/CH₄ of MWCNT@GONRs-PI MMM were more 143%and 93%than that of pristine PI membranes.The mechanism of MWCNT@GONRs-PI MMM was explained that the GONRs shell provided a selective barrier and large gas adsorption area,which contributed to enhancement of gas selectivity,while the hollow structured MWCNT core with smooth internal surface acted as a rapid transport channel,which improved the gas permeability.In addition,the rapid transport channels of MWCNTs to retard the barrier effect of GONRs to some extent.Then,MWCNT@GONRs with low oxidized degree was fabricated by modified method,which could retard the barrier effect of GONRs to some extent.And MWCNT@GONRs with low oxidized degree were mixed into Pebax MH-1657 for effective gas separation.The results showed that the MMM with 1 wt%loading of MWCNT@GONRs showed the highest separation factor?80 for CO₂/N₂ and 23 for CO₂/CH₄?and a high CO₂ permeability?about 179 Barrer?at 4 bar and 35 ^oC for dry gas streams,which is considerably better than that of pristine Pebax membrane,far surpassing the upper bound line of Robeson in 2008.The GONRs shell provided a selective barrier and large gas adsorption area,which contributed to the enhancement of gas selectivity,while the hollow structured MWCNT core with smooth internal surface acted as a rapid transport channel,which improved the gas permeability.The unique microstructure,ease of synthesis and low filled loading make MWCNT@GONRs promising candidates to improve gas separation performance of MMMs.In this work,core/shell structured MWCNT@GONRs nanohybrids with different oxidized degrees were successfully prepared using a modified chemical longitudinal unzipping method and the effect of oxidized degree on the gas separation performance of MWCNT@GONRs-polymer MMMs was studied in detail.This work is very useful for the preparation and application of MMMs.