title: Photocatalytic inactivation of Escherichia coli by natural sphalerite suspension: effect of spectrum, wavelength and intensity of visible light.
abstract: The photocatalytic disinfection of Escherichia coli K-12 is investigated by the natural sphalerite (NS) under different spectra, wavelengths and intensities of visible light (VL) emitted by light-emitting-diode lamp (LED). The spectrum effect of VL on disinfection efficiency is studied by using white LED, fluorescent tube (FT) and xenon lamp (XE), which indicates that the "discreted peak spectrum" of FT is more effective to inactivate bacteria than "continuous spectrum" of LED and XE. Besides, the photocatalytic disinfection of bacteria is compared under different single spectrum (blue, green, yellow and red color) LEDs. The results show that the most effective wavelength ranges of VL for photocatalytic disinfection with the NS are 440-490 and 570-620 nm. Furthermore, a positive relationship is obtained between the disinfection efficiency and the VL intensity. The experiment shows that NS can completely inactivate 10(7)cfu mL(-1)E. coli K-12 within 8h irradiation by white LED with the intensity of 200 mW cm(-2) at pH 8. Moreover, the destruction process of the cell wall and the cell membrane are directly observed by TEM. Finally, no bacterial colony can be detected within a 96 h regrowth test of inactivated bacteria, which reveals that the VL-photocatalytic disinfection leads to an irreversible damage to the bacterial cells.
authors.affiliation: School of Life Sciences, The Chinese University of Hong Kong, Shatin, NT, Hong Kong SAR, China.
authors.forename: Yanmin
authors.initials: Y
authors.lastname: Chen
authors.forename: Anhuai
authors.initials: A
authors.lastname: Lu
authors.forename: Yan
authors.initials: Y
authors.lastname: Li
authors.forename: Ho Yin
authors.initials: HY
authors.lastname: Yip
authors.forename: Taicheng
authors.initials: T
authors.lastname: An
authors.forename: Guiying
authors.initials: G
authors.lastname: Li
authors.forename: Peng
authors.initials: P
authors.lastname: Jin
authors.forename: Po-Keung
authors.initials: PK
authors.lastname: Wong
mesh_terms: D001688:Biological Products / Q000737:chemistry / Q000494:pharmacology*; D002384:Catalysis; D003116:Color; D004203:Disinfection / Q000379:methods*; D048168:Escherichia coli K12 / Q000187:drug effects* / Q000254:growth & development / Q000528:radiation effects*; D008027:Light; D046529:Microscopy, Electron, Transmission; D055668:Photochemical Processes; D013057:Spectrum Analysis; D013440:Sulfides / Q000737:chemistry / Q000494:pharmacology*; D013535:Suspensions; D017967:Zinc Compounds / Q000737:chemistry / Q000494:pharmacology*
chemical_list: D001688:Biological Products; D013440:Sulfides; D013535:Suspensions; D017967:Zinc Compounds; C031238:zinc sulfide