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Recovery rates of fluorescent dye on screens and plates as spray deposition collectors
Published by the American Society of Agricultural and Biological Engineers, St. Joseph, Michigan www.asabe.org
Citation: 2018 ASABE Annual International Meeting 1800066.(doi:10.13031/aim.201800066)
Authors: Kyusuk You, Heping Zhu, JohnPaul R Abbott
Keywords: Spray deposition assessment, Recovery rate, Fluorescent intensity, Deposit collector, Photo-degradation, Droplet penetration, Stainless steel screen.
Abstract. Precise spray-deposit quantification using fluorescent tracer not only requires the reliable dye recovery of deposit collectors but also demands stable variances of fluorescent intensity for intended dye concentration. The objective of this study was to determine the most applicable dye collector among five spray deposit collectors: white plastic plates, nylon screens, and three different mesh stainless steel screens. These collectors were examined with 4 g/L of Brilliant Sulfafalvine (BSF, CAS# 2391-30-2) to compare their dye recovery capability and the photo-stability of deposited dye. The dye recovery rate was separately investigated for static drawn droplets and dynamic sprayed droplets. The photo-stability of the deposited dye were studied to observe the variance of fluorescent intensity under daylight exposure. In addition, dye leftover on used collectors and droplet penetration through meshed collectors were assessed to better understand different dye recovering rate of each collector. The lowest recovery rate for static drawn droplets was resulted in nylon screens with 87.0% (σ=9.21) whereas plastic plates and stainless steel screens recovered more than 90% of deposited dye during three replications (n=5 per collector in each replication). For the dynamic spray droplets, 60x60 and 80x80 mesh stainless steel screens recovered over 80% of deposited dye whereas nylon screens showed lower than 55% during five replications. These results were proved by the high speed imaging system that detected droplet penetration phenomena more frequently in larger open-sized mesh collectors. The photo-degradation test showed less than 3.1% of fluorescent intensity during 120min of solar exposure in all collectors. Dye residue on collectors after dissolution were verified by ten-repeated fluorimetry tests. The fluorescent intensity increased by 16.8% and 12.7% on nylon and 80x80 stainless steel screen, while less than 1% of change took place in 40x40 and 60x60 stainless steel screens during repetitions. These dye leftover were also visually inspected by digital image analysis
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