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To address the issue that dyes are recalcitrant to hydrolysis and conventional water treatment strategies, an ultraviolet light-emitting diode (UV-LED)/periodate (PI) advanced oxidation process was developed for dye removal. The results showed that this system was applicable to a wide pH range. The dyes were completely removed in 40 minutes optimally with 270 nm UV-LED and 1 mmol/L PI. NO3- and HCO3- showed inhibitory effects on dye decomposition, while Cl-, SO2-4 and humic acid had a negligible effect on the system. Quenching experiments and electron paramagnetic resonance experiments were conducted to explore the reactive species involved in the oxidation process. It was confirmed that hydroxyl radicals and singlet oxygen dominated the degradation of pollutants. In addition, the transformation products of methylene blue (MB) in the system were explored and the potential reaction pathway was proposed. Furthermore, the toxicity of MB and the transformation products were predicted via a series of in silico QSAR-based prediction approaches. It was found that the biodegradability of the transformed products was significantly improved. However, some products still exhibited acute/chronic toxicity.

When ultraviolet light-emitting diodes (UV-LEDs) are used for surface disinfection, the UV dose in some areas may exceed the required level but be insufficient in other areas. The most ideal radiation field is that with the same irradiance level at each point. In this study, a universal formula for determining the radiation field was derived, and a corresponding VBA program was coded for the mathematical simulation, analysis, and optimization of the radiation field. The radiation fields of nine UV-LED radiation patterns were simulated and analyzed. The results indicate that for a board with multiple UV-LEDs, the ratio of the radiation distance to the UV-LED spacing and the radiation patterns of the UV-LEDs are the key factors that influence the uniformity of the radiation field. Because of edge effects, a uniform radiation field can be reached only within 80% of the edge length projected directly below the UV-LED board. When the ratio of the radiation distance to the UV-LED spacing is within the range of 3 to 15, the uniformity is good (the ratio of the minimum to maximum values ≥ 81.8%). The radiation pattern with a smaller maximum emission angle is good for a relatively higher ratio of the irradiation distance to UV-LED spacing, and vice versa.

Copyright of Imaging Science & Photochemistry is the property of Imaging Science & Photochemistry Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Imaging Science & Photochemistry is the property of Imaging Science & Photochemistry Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

One photoinitiator based on the 3, 4-ethylenedioxythiophene ( EDOT) was synthesized through introducing an acetylehienyl and an acetyl group respectively into two active sites of the EDOT. The structure was characterized by ¹HNMR spectroscopy. UV-Vis absorption spectroscopy, thermal stability were also tested. We also measured its photoinitiating activity with real-time ITIR technology. The results show that the photoinit iator has good absorption in t he range of 365-405 nm, which is better than 2-isopropylthioxanthone (ITX) and suitable for UV-LED photocuring systems. Meanwhile, its thermal stability is better than ITX and the photoinitiating activity is comparable to ITX. [ABSTRACT FROM AUTHOR]

In this paper, two coumarin-carbazole based oxalate photoinitiators (2-OAME and 4-OAME) were designed and synthesized. By introducing the coumarin into carbazole group, the π-conjugated structure is enlarged, resulting to the good absorption properties in UV-visible light range. The photophysical and photochemical properties were characterized by UV-Vis absorption spectra and FT-RTIR. The two photoinitiators exhibit excellent light absorption properties in the near UV-Vis range and have good photoinitiated polymerization ability under excitation by the LED light source. The 4-OAME molecule exhibited better photoinitiated polymerization ability under the same conditions than 2-OAME. The two photoinitiators have great application potential in the field of near-ultraviolet-visible LED photopolymerization. [ABSTRACT FROM AUTHOR]

Copyright of Imaging Science & Photochemistry is the property of Imaging Science & Photochemistry Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)