Effect of DACH-K₂CO₃ Mixed Absorbent on the Performance of a CO₂ Absorption and Microalgae Conversion (CAMC) System

In light of global concerns regarding greenhouse gas emissions, a CO2 absorption and microalgae conversion (CAMC) system has been proposed as a potential solution. This study investigated the impact of a mixed absorbent containing trans-1,4-diaminocyclohexane (DACH) and K2CO3 on Chlorella L166's growth and the CAMC system and explored the regulatory mechanism. Results showed that a 1:50 mixture of DACH and K2CO3 increased the dissolved inorganic carbon content, enabling better growth and better fixation of CO2 by Chlorella L166. The chlorophyll a, carotenoid, and carbohydrate contents were 11.89, 16.67, and 31.28% higher than those of the control group (0:50), respectively. Transcriptome analysis suggested that the mixed absorbent altered gene expression in microalgal cells and influenced their cellular composition. Upregulation of processes such as photosynthesis, the Calvin cycle, and carbohydrate metabolism facilitated the redirection of more energy toward carbon fixation and carbohydrate accumulation, thereby improving the growth performance of Chlorella L166. Overall, the mixed absorbent is an effective strategy to enhance the performance of the CAMC system.