Application of Carbonic Anhydrase Membrane in Direct Air Carbon Capture by Microalgae and Enhancement of Carbon Sequestration Performance

To address the challenges of low C()2 mass transfer efficiency and solubility in microalgae photobioreactors in direct air carbon capture, this paper employs experimental methods to prepare a nylon fiber membrane coated -with carbonic anhydrase (CA). By utilizing CA ' s catalytic properties to convert C()2 into bicarbonate, a novel photobioreactor is proposed to enhance C()2 solubility and conversion rate in microalgae solutions. The reactor's performance, with and without the CA-coated nylon floating membrane, is evaluated for microalgae cultivation and carbon sequestration. Furthermore, the impact of membrane porosity and CA loading on carbon fixation efficiency is investigated. The experimental results demonstrate that the prepared CA-coated nylon fiber membrane increases the C()2 conversion rate by 62. 7%. Through durability testing, the CA activity remains robust even after five cultivation cycles, with only an 11. 3% decline in performance. Compared to traditional aeration methods, the novel photobioreactor increased microalgae biomass production by 29. 7% and carbon sequestration efficiency by 65%. Moreover, an increase in membrane porosity and light transmittance enhances the carbon sequestration efficiency per unit of CA loading, showing a 13% improvement in the carbon fixation rate per unit of CA for the control group with a 24. 75% open area ratio compared to the non-porous control. This study provides a novel approach for further enhancing the carbon sequestration efficiency of microalgae in direct air capture. © 2024 Xi'an Jiaotong University. All rights reserved.