Enhancing microalgal CO2 fixation with amine-loaded hollow fiber membranes

WANG Yaqin; LIU Jingchao; BAI Liju; LU Shijian; CHEN Siming; TANG Hua

doi:10.13226/j.issn.1006-6772.WS25051904

Abstract：Microalgae carbon sequestration plays a crucial role in addressing greenhouse effect,energy crisis,and promoting low-carbon economic development.However,low carbon sequestration efficiency is the bottleneck problem limiting the development of this technology.Therefore,this article proposes the use of organic amine supported hollow fiber membranes(hydrophobic polypropylene(PP)membranes)to improve microalgae carbon sequestration performance.Firstly,hydrophobic modification is performed on the hollow fiber membrane,followed by physical loading of 2-amino-2-methyl-1-propanol(AMP)onto the hollow fiber membrane;Then,immerse it in a microalgae culture system as a medium for CO2 gas to enter the culture medium.During the process,AMP loaded PP membrane can enhance the mass transfer of CO2 to microalgae culture medium,thereby improving the efficiency of CO2 removal;AMP loaded PP membrane can serve to separate the chemical reaction field between CO2 and amines,as well as the biological reaction field for microalgae to absorb CO2,avoiding complex mixing reactions;The AMP on the PP membrane and the amino formate formed by the reaction between AMP and CO2 do not dissolve in the culture medium and do not directly contact microalgae cells,greatly reducing damage to microalgae cells and not affecting cell photosynthesis,thereby improving efficiency;The AMP loaded PP membrane and microalgae system exhibit a separation state,which can be separated by simple physical methods.The experimental results showed that the 123.16 mg/L AMP-PP membrane reinforcement technology can significantly increase biomass concentration(0.88 g/L)and CO2 fixation efficiency(183.23 mg/(L·d)).Compared with the Blank group,Blank PP group,and 123.16 mg/L AMP group,the biomass concentration increased by 28.05％,18.04％,and 183.57％,respectively,and the CO2 fixation efficiency increased by 58.23％,44.16％,and 168.42％,respectively.At the same time,this enhanced technology eliminates oxidative stress(decreased SOD activity)and cell damage caused by direct contact with AMP through physical isolation(fractal dimension increased by only 5.9％).The amino formate generated after CO2 adsorption on the surface of the aminated membrane increases the concentration of dissolved inorganic carbon(DIC)in the culture medium through hydrolysis reaction,and the CO2 removal efficiency reaches 83.5％,significantly better than the dissolved AMP system,highlighting the effectiveness of this membrane mediated method in microalgae CO2 fixation.