Preparation of titania based biocatalytic nanoparticles and membranes for CO₂conversion

Abstract

Biomimetic route of CO2 conversion catalyzed by carbonic anhydrase (CA) is an attractive option for carbon capture and storage due to the high efficiency and specificity of CA in CO2 hydration. Preparation of TiO2 based biocatalytic naonparticles and membranes via CA immobilization facilitates the reuse of the enzyme and could be potentially integrated in a gasliquid membrane contactor for high efficient CO2 capture. In this work, different immobilization protocols were compared based on CA loading, activity and stability. For biocatalytic nanoparticles, over 80% activity recovery and 163 mg/g support was achieved. Repeated reuse and recovery of the biocatalytic nanoparticles over twenty cycles showed only modest loss in activity. For the biocatalytic membranes, the nanostructure of the titania coating and the pH values during immobilization were examined to optimize the biocatalytic performance. Biocatalytic membranes prepared at pH 6 with two cycles of sol-gel coating were able to immobilize 700 µg CA/cm 2 nominal membrane area. The CO2 hydration efficiency of the biocatalytic nanoparticles and membranes were examined, and only marginal loss of catalytic efficiency was observed when compared with their free CA counterpart, indicating good potential to apply such biocatalytic nanoparticles and membranes for CO2 conversion.

Biocatalytic Janus membranes for CO2 removal utilizing carbonic anhydrase

“…28 For the free CA, 0.2 ml CA was mixed with 2.4 ml Tris buffer solution (pH 8) and 0.2 ml p-NPA (2.2 Â 10 À2 M in acetonitrile).…”

“…28 Aer each cycle, the membranes were rinsed thoroughly with Tris buffer (pH 7). The biocatalytic membrane was tested for up to 20 catalytic cycles using the p-NPA assay with 0.5 h for each cycle.…”

Janus Membranes with Asymmetric Wettability for Fine Bubble Aeration

“…[ 7 ] The widest applied industrial processes are wet scrubbing and fl uid bed reactor. The removal of CO 2 from mixed gas, such as fl ue gas purifi cation and natural gas sweetening, has important environmental and economic signifi cance.…”

“…The pore size shows no obvious change after modifi cation ( Figure S3, Supporting Information). [7][8][9] For aeration in these processes, the bubble size signifi cantly affect the gas/liquid mass transfer and the whole process efficiency. However, the water drops gradually permeate through the membrane pores with the decrease of contact angle and drop conjugate diameter (CD), which is caused by the directional transport of water within a Janus membrane.…”

“…Figure 2 c shows that a hemispherical bubble grows on the gas/solid interface when bubbling through the nascent membrane. [7][8][9] For aeration in these processes, the bubble size signifi cantly affect the gas/liquid mass transfer and the whole process efficiency. In contrast, a spherical bubble is observed in the Bubble aeration has been widely applied in many processes for energy production, environmental remediation, chemical engineering, and aquaculture.…”