Preparation And Performance Of CO₂ Separation Membrane Based On Carbonic Anhydrase And Biomimetic Enzymes

CO₂ is one of the main gases that contribute to the greenhouse effect,its capture and storage has become a hot topic.As a new type of green separation technology,membrane separation has a good application prospect,and the combination of biological enzymes and membranes has good prospects.Carbonic anhydrase?CA?has an efficient catalytic effect on CO2,which can greatly improve CO2 capture efficiency.At the same time,in order to reduce costs,a biomimetic enzyme that can catalyze CO₂ was prepared.In this paper,composite membranes and mixed matrix membranes with catalytic function were prepared by combining biological enzymes and biomimetic enzymes with membranes,respectively.Then applied it to the CO2/N2separation system,examined the separation performance of CO₂.The main contents are as follows:?1?CA molecules were embedded into metal–organic frameworks?MOFs?via physical absorption and chemical bonds,which could overcome the enzymatic inactivation and the poor separation property of pristine MOFs materials.And then,these nanocomposites?enzyme embedded MOFs?as the crystal seeds were in situ grown on oriented halloysite nanotube layers to develop novel biocatalytic composite membranes.These membranes exhibited optimal separation performance with a CO2/N2 selectivity of 165.5,about 20.9 fold higher than that of the membrane without embedded CA molecules,surpassing the Robeson upper bound?2008?.At the same time,the CO₂ permeance increased about 3.2 fold?from 7.6 GPU to 24.16 GPU?.Importantly,the biocatalytic composite membranes showed good stability and mechanical properties and were easily scalable,which could be extended to industrial applications.?2?Starting from the structure of CA,a novel biomimetic material?Co-2,6-Bis?2-benzimidazolyl?pyridine,CoBBP?which owns the similar molecular structure with CA enzyme but with higher stability and lower price was successfully synthesized.The excellent thermal stability,dispensability and high CO₂ selectivity endow CoBBP a promising alternative for CA.Then,combining this biomimetic material with block copolymer Pebax-1657 using the solvent evaporation,a series of Pebax-CoBBP mixed matrix membranes were constructed.Compared to the pristine Pebax-1657,the Pebax-CoBBP mixed matrix membrane with the optimized 1.33 wt%CoBBP loading showed improved CO₂ permeability of 675.5 Barrer and CO₂/N₂selectivity of 62,surpassing the Robeson upper bound?2008?.Furthermore,the hydrogen bonds between CoBBP and polyamide chains,improved the mechanical properties of the membrane,enabling it to have good long-term operational stability.In short,this work could provide a promising method to exploit the alternative of CA enzyme and the fabrication of biomimetic membranes.