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Article

Degradation of Tryptophan by UV Irradiation: Influencing Parameters and Mechanisms

College of Civil Engineering and Architecture, Zhejiang University, Hangzhou 310058, China
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Author to whom correspondence should be addressed.
Academic Editor: Sergi Garcia-Segura
Water 2021, 13(17), 2368; https://doi.org/10.3390/w13172368
Received: 22 July 2021 / Revised: 22 August 2021 / Accepted: 23 August 2021 / Published: 28 August 2021
(This article belongs to the Section Wastewater Treatment and Reuse)
The chlorination of dissolved amino acids can generate disinfection by-products (DBPs). To prevent the formation of DBPs, we examined the UV-induced degradation of tryptophan (Trp). In order to further understand the impact of UV disinfection on Trp, the effects of initial concentrations of Trp, pH, temperature, concentrations of NO3, HCO3 and Cl on Trp removal were investigated, and a degradation mechanism was also proposed. The results demonstrated that degradation fitted a pseudo first-order reaction kinetic model. The degradation of Trp was mainly caused by direct UV degradation. The apparent rate constant kobs decreased with the increase in initial Trp concentration and increased with increases in pH and temperature. The thermal degradation activation energy was 19.65 kJ/mol. Anions in water also had a significant influence on the degradation of Trp. HCO3 and NO3 contributed to the kobs of Trp, but Cl inhibited the degradation rate. By electron paramagnetic resonance (EPR) spectroscopy, ·OH was proven to be formed during the degradation of Trp by UV. Based on the intermediate products of C11H15NO3, C10H15N and C9H13N detected by LC-MS-MS, the degradation pathway of Trp was speculated. View Full-Text
Keywords: tryptophan; UV photolysis; pseudo first-order kinetics; ·OH; degradation tryptophan; UV photolysis; pseudo first-order kinetics; ·OH; degradation
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MDPI and ACS Style

Zhang, K.; Fei, W.; Ji, J.; Yang, Y. Degradation of Tryptophan by UV Irradiation: Influencing Parameters and Mechanisms. Water 2021, 13, 2368. https://doi.org/10.3390/w13172368

AMA Style

Zhang K, Fei W, Ji J, Yang Y. Degradation of Tryptophan by UV Irradiation: Influencing Parameters and Mechanisms. Water. 2021; 13(17):2368. https://doi.org/10.3390/w13172368

Chicago/Turabian Style

Zhang, Kejia, Weicheng Fei, Jingxuan Ji, and Yulong Yang. 2021. "Degradation of Tryptophan by UV Irradiation: Influencing Parameters and Mechanisms" Water 13, no. 17: 2368. https://doi.org/10.3390/w13172368

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