Research
| Title： | Comparative study of CO2 nanobubbles and macrobubbles: Effects on water chemistry, microalgal growth, and carbon utilization |
|---|---|
| First author： | Li, Lili; Wei, Jingru; Lee, Yi-Ying; Zhang, Yihan; Xue, Shan; Atukuri, Sowmya; Li, Yantao; Marhaba, Taha; Zhang, Xuezhi; Zhang, Wen |
| Journal： | WATER RESEARCH |
| Years： | 2025 |
| DOI： | 10.1016/j.watres.2025.124714 |
| Abstract： | Algal biotechnology presents a cost-effective approach for simultaneous carbon dioxide (CO2) capture and bioproduct generation. However, conventional gas delivery approaches (e.g., macro and micro-bubbles) suffer from low gas-liquid mass transfer efficiency (KL center dot a) and CO2 utilization. This study investigated the aqueous properties of CO2 nanobubbles and impacts on the CO2 mass transfer, utilization, and microalgal growth. Results revealed that direct injection of CO2 nanobubbles in DI water achieved rapid CO2 saturation (1.48 f 0.08 g center dot L-1) and nanobubble density (1.5 x 108 particles center dot mL-1) within 1 minute. By contrast, the circulation mode produced a higher nanobubbles concentration (2.6 x 108 particles center dot mL-1) after 20 min with a similar dissolved CO2 concentration. Accordingly, the volumetric mass transfer coefficient (KL center dot a) of CO2 nanobubbles in DI water reached 12.41 f 3.49 h-1 (circulation mode) and 18.91 f 7.68 h-1 (direct mode), exceeding that of macrobubbles (10.18 f 2.38 h-1). Compared to macrobubbles, the use of CO2 nanobubbles in Scenedesmus obliquus cultivation increased biomass by 10.11 f 0.01% over 14 days and garnered carbon utilization efficiency (CUE) to 27.86 f 0.63%, supported by the enhanced CO2 mass transfer or carbon transfer efficiency. These findings highlight the potential of nanobubble technology in algal biotechnology applications and global CO2 emission mitigation. |
