The Multi-Hollow Surface Dielectric Barrier Discharge Usage for the Seeds' Treatment Aimed to the Dustiness Decrease of Free-Floating Particles from Agrochemicals

Abstract

The Multi-hollow Surface Dielectric Barrier Discharge (MSDBD) generated in ambient air at atmospheric pressure was used to treat maize, pea, wheat and parsley seeds. Plasma exposure was applied as a pre-treatment before the seeds coating with agrochemicals. The aim of this study was to decrease the dustiness of coated seeds using plasma pre-treatment. The optimization process of plasma treatment parameters for individual seed species consisted of choosing a suitable exposure time (20 s, 60 s) and airflow (10 L/min, 15 L/min). The plasma made the seeds' surface more hydrophilic; therefore, better agrochemicals adhesion was achieved on the seeds' surface. Wettability improvement was demonstrated via water uptake of seeds and apparent contact angle change. Ambient air plasma at a 15 L/min flow rate was measured using optical emission spectroscopy, and the values of vibrational (3000 K) and rotational (347 K) temperatures were obtained from spectra simulation. The surface temperature of the MSDBD ceramics plate was measured with a thermal camera for different gas flow rates and constant input power of 30 W because the temperature is crucial parameter for seed treatment. The surface morphology was not affected due to plasma treatment, even for a longer exposure time. A significant decrease in dustiness measured according to the Heubach method was achieved for pea (57.1%) and parsley (41.4%) seeds. A lower decrease in dustiness was registered in the case of wheat (14.6%) and maize (17%) seeds. The results showed that MSDBD plasma generated in the air at optimized conditions is able to decrease the coated seed dustiness regardless of seed type and size, while seeds germination and surface coverage percentage remained unchanged.