Enhancing Interface Reactions by Introducing Microbubbles into a Plasma Treatment Process for Efficient Decomposition...

Area of Science:

• Environmental Chemistry
• Water Treatment Technologies
• Plasma Science

Background:

• Perfluoroalkyl compounds (PFAS) are persistent environmental pollutants due to strong C-F bonds.
• Efficiently removing perfluorooctanoic acid (PFOA) from contaminated water is a significant environmental challenge.
• Conventional treatment methods struggle with the stability of PFOA.

Purpose of the Study:

• To investigate the mineralization of high-concentration PFOA using a novel nonthermal plasma reactor.
• To evaluate the impact of microbubbles (MBs) with different carrier gases on PFOA degradation efficiency.
• To explore the degradation pathways and energy efficiency of the proposed treatment.

Main Methods:

• Utilized a needle-plate pulsed discharge reactor integrated with a water jet (NPDW).
• Introduced microbubbles (MBs) using air, nitrogen, or argon as carrier gases to enhance interfacial reactions.
• Analyzed PFOA removal efficiency, defluorination ratio, and identified transformation products.

Main Results:

• Achieved high PFOA removal efficiencies (up to 95.3%) and defluorination ratios (≥50%) within 2 hours.
• Microbubbles significantly enhanced PFOA enrichment at the liquid surface and expanded plasma discharge.
• Identified degradation mechanisms including decarboxylation, hydroxylation, hydrogenation, and defluorination; process showed robustness across various water matrices.

Conclusions:

• Nonthermal plasma technology with microbubbles offers an effective and environmentally friendly solution for PFOA degradation.
• The NPDW reactor demonstrates potential for treating PFOA in diverse real-world water conditions.
• Further research into optimizing energy efficiency and understanding byproduct formation is warranted.