Effect of adding tertiary amine TMEDA and space hindered amine DACH on the CO2 chemical absorption-microalgae conversion system

The CO2 chemical absorption-microalgae conversion (CAMC) system combines the advantages of chemical ab-sorption and biological methods to achieve simultaneous low-energy CO2 capture and green resource applica-tion. Tertiary amines and space hindered amines are theoretically more suitable chemical absorbents for CAMC systems, but there are still relatively few related studies. Therefore, tertiary amine TEMDA (N,N,N ',N '-Tetra-methylethylenediamine) and space hindered amine DACH (trans-1,4-Diaminocyclohexane) with Chlorella sp. L166 were selected to add to CAMC system for evaluation in this work. As a result, the addition of TMEDA increased the cell concentration of Chlorella sp. L166 by 19.92% and the specific growth rate by 14.65%. The carbon conversion efficiency increased to 43.29%, and carbon sequestration capacity increased by 49.07% and achieved 123.27 mg L-1 d-1. In terms of added value products, the protein content reached 19.80 mg/L, which increased by 45.71% compared to the control. In addition, the larger pyrenoid of Chlorella sp. L166 was iden-tified by transmission electron microscopy (TEM), which explained the improved carbon assimilation from the microstructure. Therefore, this study broadened the applicability of CAMC system and confirmed the potential of tertiary amines and space hindered amines to be added to CAMC system, which has implications for further development of CAMC system.