Atmospheric Pressure Cold Plasma as a Potential Technology to Degrade Carbamate Residues in Water

Cold plasma technology is an advanced oxidation process (AOP), which has shown significant potential for pesticide degradation. The aim of this study was to determine the degradation efficacy and transformation products for cold plasma treated carbamates in water. The dissipation of three carbamates, namely, carbaryl, methiocarb and aminocarb were evaluated as a function of treatment voltage (70, 80, and 90 kV) and duration (1 to 5 min) using a dielectric barrier discharge. Significant and rapid reduction in the concentrations of carbaryl, methiocarb and aminocarb were observed after cold plasma treatment. A maximum degradation of 50.5% in carbaryl, 99.6% in methiocarb and 99.3% in aminocarb was achieved after 5 min of treatment at an applied voltage of 90 kV. The plasma light emission was evaluated using optical emission spectroscopy revealing the production of reactive oxygen and nitrogen species, besides gas temperatures closer to ambient. The reaction intermediates were identified mostly as oxidation products from the respective carbamates, and reaction pathways were proposed. The toxicity of the degradation products, where available, was reviewed. Overall, this study shows the potential of cold plasma technology as an alternative approach for rapid dissipation of agrochemicals and other micro-pollutants in water and wastewater.