Controllable Construction Of CO₂ Transmission Channel For Layered Membrane And Study On Ion Transfer Mechanism

As an emerging technology for carbon capture,membrane separation technology has become a research hotspot at present attributed to the advantages of high efficiency,energy saving and convenience.Membrane materials,regarded as the core of membrane separation technology,have made great progress,and a variety of membrane materials have been obtained.In fact,the development of membrane materials is based on researchers’cognition in CO₂ transfer mechanism.In this paper,based on CO₂hydration reaction which can generate bicarbonate and protons under wet condition,and with the two-dimension material graphene oxide as main membrane material,we construct transfer channels with different properties between layer and layer to study the transfer characteristics after CO₂ was transformed into ions in the membrane and reveal the transfer mechanism of CO₂ ions.On this basis,the membrane structure tailoring and performance improving are realized,which can be used as a reference for the development of new membrane materials.Following are the main contents and conclusions of this paper:（1）The defect-free lamellar film was obtained by means of shock,varying pressure and heat treatment.Amphoteric betaine and other contrast small molecules were introduced into the membranes to construct anion-cation channels and other channels for comparing.It was found that different membranes showed different characteristics about layer space and free volume attributed to the diverse distributions of small molecules in membranes.Comparing the CO₂ separation performance of the membranes at different temperatures and pressures,the membrane with anion-cation channels had the best performance thanks to that quaternary ammonium cation and carboxylate anion could achieve the efficient simultaneous transfer of bicarbonate and hydrogen proton.Compared with GO membrane,the rate of CO₂ permanence at room temperature reached 935.2 GPU and CO₂/N₂ selectivity reached 10.55.At 90 ^oC,CO₂permanence reached 2365 GPU,and the CO₂/N₂ selectivity reached 73.43.In the pressure experiment,we also found that the rate of CO₂ transfer process and the selectivity decline rate of CO₂/N₂ decreased significantly,which were different from the results of carrier saturation in traditionally promoted transfer membranes.（2）Based on the explore about the transfer mechanism of CO₂ ions,we determined that betaine can construct anion-cation channels in GO lamellar membranes,and the efficient simultaneous transfer of the bicarbonate and hydrogen proton under wet condition is realized.Besides,piperazine,a micromolecular transfer carrier,was introduced into GO laminar membranes containing anion-cation channels.On one hand,it can effectively accelerate the rate of CO₂ transfer as a carrier of reaction selection mechanism.On the other hand,it can promote the hydration reaction,thus enhance the promoting transfer process based on ion transfer mechanism.Compared with the membrane with betaine,the rate of CO₂ permanence of the co-intercalation membrane at room temperature reached 1221 GPU and CO₂/N₂ selectivity reached 16.21.At 90^oC,CO₂ permanence reached 2843 GPU,and the CO₂/N₂ selectivity reached 146.9.