Efficient Remediation of Trifluralin-Contaminated Soil Using Non-thermal DBD Plasma as an AOP: Optimization via RSM

Trifluralin is a persistent dinitroaniline herbicide with strong soil sorption, low water solubility, and documented ecological and potential human-health risks. Conventional physicochemical and biological remediation methods for trifluralin-contaminated soils can be limited by soil properties, chemical demand, and energy consumption, and may generate toxic intermediates. This study investigated a non-thermal dielectric barrier discharge (DBD) plasma process for trifluralin removal from soil and optimized key operating variables using response surface methodology (RSM). A double-dielectric, plane-to-plane DBD reactor powered by a ۲۰ kHz microsecond pseudo-pulsed high-voltage supply (up to ۳۳.۴ kV) was employed, with air injected at ۱ L min' through a ۲ mm discharge gap containing ۵ g of contaminated loam soil (initial trifluralin concentration: ۱۰۰ mg kg-¹). A central composite design evaluated the effects of discharge voltage (XV), treatment time (XT), and soil moisture content (XM) on removal efficiency, quantified by HPLC after acetonitrile extraction. Trifluralin removal increased with increasing discharge voltage, treatment time, and moisture content within the tested ranges, reaching ۹۶.۷۲% at ۱۴.۸ kV. At zero-coded levels of other variables, removal rose from ۷۸.۵۸% at ۵ min to -۹۰% at ۲۵ min, with a tendency to plateau beyond -۲۰ min, likely due to reduced parent-compound availability and competition from degradation by-products for reactive species. Increasing moisture from ۰% to ۱۲% (w/w) enhanced removal from ۷۹.۵% to ۸۹%, with diminished incremental gains at higher moisture levels attributed to partial pore blockage and mass- transfer limitations. RSM analysis supported the identification of operating conditions that maximize trifluralin removal, demonstrating that microsecond pseudo-pulsed DBD plasma is an effective and low-chemical-input approach for remediating trifluralin-contaminated soils.

کلیدواژه ها:

Trifluralin ، Soil remediation ، Dielectric barrier discharge (DBD) plasma ، Non-thermal plasma ، Advanced oxidation processes (AOPs) ، Response surface methodology (RSM)