Tang, Han; Hu, Jiajun; Tong, Wang Kai; Liu, Jiaxiang; Jiang, Piao Yi; Zhang, Jun Bo; Wang, Jia; Zou, Jia Jie; Zhang, Kexuan; Yue, Mei Ru; Liu, Jia Bing; Gao, Min-tian; Liu, Nan; Li, Jixiang

SEPARATION AND PURIFICATION TECHNOLOGY

2025, ,

Tang, Han; Hu, Jiajun; Tong, Wang Kai; Liu, Jiaxiang; Jiang, Piao Yi; Zhang, Jun Bo; Wang, Jia; Zou, Jia Jie; Zhang, Kexuan; Yue, Mei Ru; Liu, Jia Bing; Gao, Min-tian; Liu, Nan; Li, Jixiang

Petroleum hydrocarbons in soil are toxic, persistent, and harmful to human health and ecosystems, with their elution being key for soil remediation. This study attempted to regulate nanobubble properties by adjusting mixed gas composition, thereby enhancing their ability to promote the migration of soil pollutants. Mathematical models were established to explore the relationship between different gas sources (including CO2, N-2, and O-2) and nanobubble properties, aiming to find the optimal gas source composition. The results showed multiple synergistic effects among different gas sources, which enabled the tunability of mixed-gas nanobubble properties to exceed the limits of single-gas nanobubbles. Furthermore, by integrating the distinct functionalities of single-gas nanobubbles, mixed-gas nanobubbles could be designed with multiple functionalities (or the avoidance of certain). The optimized mixed-gas nanobubbles (MGBO) were prepared from 50 % N-2 and 50 % O-2. After 7-day storage at 100 mmol/L salt concentration, MGB-O's residue rate (69 %) exceeded that of single-gas nanobubbles (35 % similar to 42 %). Its flow velocity (367 mL/min) in porous media was also higher than that of single-gas nanobubbles (317-350 mL/min) and sample without nanobubbles (300 mL/min). These enhanced characteristics enabled MGB-O to achieve a 40 % petroleum hydrocarbon elution rate, representing nearly a 6-fold improvement over conventional water flushing (6 %). Post-treatment analysis revealed enriched strictly-aerobic hydrocarbon-degrading microbes (Pontibacter genus increased from 0.02 % to 43.17 %) and 53 % similar to 5982 % increase in hydrocarbon-degradation enzyme genes, attributable to the oxygen-delivery capability of MGBO. This study established a tunable nanobubble design framework, enabling cost-effective and stable operations for enhanced physical elution and biodegradation of petroleum hydrocarbon-contaminated soil.