Utilization of enhanced electrolytic bubbles in electrooxidation for efficient refractory organics removal

Area of Science:

• Environmental Chemistry
• Electrochemistry
• Water Treatment

Background:

• Electrooxidation effectively removes refractory organics but is energy-intensive due to non-selective oxidation.
• The oxygen evolution reaction (OER) in conventional electrooxidation contributes minimally to organic matter removal.
• Enhancing electrolytic bubble performance is crucial for improving the efficiency of organic pollutant degradation.

Purpose of the Study:

• To enhance conventional electrolytic bubbles for improved organic matter removal during electrooxidation.
• To investigate the use of a membrane electrochemical reactor (MER) to separate and stabilize electrolytic bubbles.
• To explore the impact of surfactants on bubble-electrochemistry interactions for humic acid removal.

Main Methods:

• Design and implementation of a membrane electrochemical reactor (MER) to separate H₂ and O₂ bubbles.
• Utilizing humic acid as a model refractory organic pollutant.
• Employing surfactants, specifically cetyltrimethylammonium bromide (CTAB), to modify bubble surface charge and enhance interaction with humic acid.
• Analysis of bubble stability, zeta potential, and humic acid removal efficiency.
• Investigating the reusability of CTAB via foam fractionation.

Main Results:

• The MER system demonstrated higher MER O₂ bubble stability compared to conventional methods.
• Addition of CTAB (80 mg/L) intensified the positive charge of MER O₂ bubbles, leading to 92.8% humic acid removal at a low oxidation rate (<3.7%).
• Zeta potential analysis confirmed the charge modification of bubbles by MER and CTAB.
• CTAB was successfully reused after foam fractionation, indicating a sustainable application.

Conclusions:

• Enhanced electrolytic bubbles, particularly MER O₂ bubbles modified with CTAB, offer a highly efficient method for refractory organic removal.
• The MER system and surfactant modification significantly reduce energy consumption in electrooxidation processes.
• This approach provides a novel strategy for sustainable and energy-efficient water treatment, focusing on humic acid removal.