Assessment of Fluorescent Dye Brilliant Sulfaflavine Deposition on Stainless Steel Screens as Spray Droplet Collectors

Abstract

Abstract. The fluorescent dye Brilliant Sulfaflavine (BSF, CAS 2391-30-2) was investigated to determine its photo-stability and recovery on five spray deposition collectors: white plastic plate, nylon screen, and stainless steel (SS) screens of three mesh sizes (40, 60, and 80). The photo-stability of the deposited dye was determined by measuring the variance in fluorescence intensity after daylight exposure. The recovery rates were investigated with statically dispensed droplets and dynamically discharged droplets. In addition, droplet penetration through the screen collectors and the amount of unrecovered dye on reprocessed collectors were assessed to better understand the differences in dye recovery rates among different collector types. Photo-degradation tests verified that all collector types were insignificant in fluorescence degradation (<3.1%) after 120 min of solar exposure. Nylon screens had the lowest dye recovery rate (87.0%) for statically dispensed droplets, whereas plastic plates and SS screens recovered more than 90% of deposited dye. For dynamically discharged droplets, the 60-mesh and 80-mesh SS screens recovered more than 70% of the deposited dye, whereas nylon screens showed less than 50% recovery rate. These results were substantiated visually with a high-speed imaging system that detected droplets penetrating more frequently through screens with larger mesh openings. Throughout ten continuous reprocessing cycles of the fluorimetry test, the fluorescence intensity on reprocessed nylon and 80-mesh SS screen collectors increased by 16.8% and 12.7%, respectively, while there was less than 1% change in fluorescence intensity on the 40-mesh and 60-mesh SS screens. These results were clarified through dye residue verification using digital image analysis. Keywords: Fluorescence intensity, Photo-degradation, Recovery rate, Spray deposition assessment, Stainless steel screen.