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Inactivation of Bacillus subtilis Spores Using Various Combinations of Ultraviolet Treatment with Addition of Hydrogen Peroxide
Author(s) -
Zhang Yiqing,
Zhou Lingling,
Zhang Yongji,
Tan Chaoqun
Publication year - 2014
Publication title -
photochemistry and photobiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.818
H-Index - 131
eISSN - 1751-1097
pISSN - 0031-8655
DOI - 10.1111/php.12210
Subject(s) - bacillus subtilis , hydrogen peroxide , spore , chemistry , ultraviolet , radical , kinetics , nuclear chemistry , reaction rate constant , bacteria , microbiology and biotechnology , biochemistry , biology , materials science , genetics , physics , optoelectronics , quantum mechanics
This study aims at comparing the inactivation of Bacillus subtilis spores by various combinations of UV treatment and hydrogen peroxide (H 2 O 2 ) addition. The combinations included sequential (UV–H 2 O 2 , H 2 O 2 –UV) and simultaneous (UV/H 2 O 2 ) processes. Results showed that B. subtilis spores achieved a certain inactivation effect through UV treatment. However, hardly any inactivation effect by H 2 O 2 alone was observed. H 2 O 2 had a significant synergetic effect when combined with UV treatment, while high irradiance and H 2 O 2 concentration both favored the reaction. When treated with 0.60 m m H 2 O 2 and 113.0 μW/cm 2 UV irradiance for 6 min, the simultaneous UV /H 2 O 2 treatment showed significantly improved disinfection effect (4.13 log) compared to that of UV–H 2 O 2 (3.03 log) and H 2 O 2 –UV (2.88 log). The relationship between the inactivation effect and the exposure time followed a typical pseudo‐first‐order kinetics model. The pseudo‐first‐order rate constants were 0.478, 0.447 and 0.634 min −1 , for the UV‐H 2 O 2 , H 2 O 2 –UV and UV/H 2 O 2 processes, respectively, further confirming the optimal disinfection effect of the UV/H 2 O 2 process. The disinfection could be ascribed to the OH radicals, as verified by the level of para ‐chlorobenzoic acid ( p CBA).