Organic pollutants degradation using plasma with simultaneous ammonification assisted by electrolytic two-cell system

Area of Science:

• Environmental Science and Engineering
• Chemical Engineering
• Water Treatment Technologies

Background:

• Atmospheric non-thermal dielectric barrier discharge (DBD) plasma is a promising, cost-effective, and eco-friendly technology for water treatment.
• However, limitations exist in its application, particularly in completely degrading certain pharmaceutically active compounds (PhACs) and managing by-products.

Purpose of the Study:

• To investigate the efficacy of DBD plasma in degrading three model PhACs: sulfamethoxazole (SMX), ibuprofen (IBP), and norfloxacin (NFX).
• To optimize DBD plasma parameters, including gas type and flow rate, for maximum PhAC degradation.
• To develop and evaluate a hybrid plasma-electrolysis system for enhanced PhAC removal and by-product management.

Main Methods:

• Atmospheric DBD plasma was employed using various gases (Ar, N2, O2, air) at flow rates of 1-4 L min−1 to disrupt SMX, IBP, and NFX.
• A coupled system integrating DBD plasma with electrolysis, utilizing Cu/reduced Cu nanowire (R-CuNw) as anode/cathode, was developed.
• Degradation efficiency, by-product formation (NO2−, NO3−), and energy consumption were analyzed.

Main Results:

• Air plasma at 2 L min−1 showed the highest degradation efficiency, completely removing NFX and SMX but only 10% of IBP within 30 min.
• The coupled plasma-electrolysis system achieved complete removal of all three PhACs within 30 min.
• The hybrid system effectively reduced problematic NO2− and NO3− to ammonia (NH3) via cathodic reduction, with significantly lower energy consumption (0.04 kWh L−1) and treatment cost (0.003 USD L−1) compared to plasma alone.

Conclusions:

• Coupling DBD plasma with electrolysis offers a superior water remediation strategy for comprehensive PhAC removal and by-product neutralization.
• The system's high efficiency, low cost, and production of valuable ammonia by-product demonstrate significant potential for practical water treatment applications.
• This integrated approach addresses the limitations of standalone plasma treatment and presents a sustainable solution for environmental challenges.