US EPA

7425416 

Journal Article 

Degradation of cyanotoxin microcystin-LR in synthetic and natural waters by chemical-free UV/VUV radiation 

Chintalapati, P; Mohseni, M; , 

2020 

Yes 

Journal of Hazardous Materials
ISSN: 0304-3894
EISSN: 1873-3336 

ELSEVIER 

AMSTERDAM 

381 

120921 

English 

31374374 

10.1016/j.jhazmat.2019.120921 

WOS:000504778400016 

https://linkinghub.elsevier.com/retrieve/pii/S030438941930874X
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This study investigated the capability of ultraviolet radiation at 254 nm and 185 nm (UV/VUV) to degrade cyanotoxin microcystin-LR (MC-LR). Results showed 70% toxin reduction solely by 254 nm direct photolysis (ε254 = 13,225 ± 814 M-1cm-1; Φ254 = 0.29 ± 0.03 mol/Einstein). The addition of 185 nm increased MC-LR degradation through advanced oxidation by •OH (k•OH,MC-LR = 2.25 ± 0.39 × 1010 M-1s-1). Alkalinity and organics (DOC) reduced MC-LR degradation by scavenging •OH (kobs,MilliQ = 0.117 cm2/mJ; kobs,50ppmAlk. = 0.0497 cm2/mJ; kobs,6ppmDOC = 0.019 cm2/mJ). Chloride absorbed 185 nm, impacting •OH formation and generating Cl•, while also scavenging •OH. However, Cl• is reactive and •OH scavenging is reversible, resulting in relatively low impact on MC-LR degradation (kobs,50ppmCl = 0.0939 cm2/mJ). In natural water, MC-LR could be degraded from a typical concentration (˜15 μg/L) to below detection (<0.5 μg/L) with a UV254 fluence of 200 mJ/cm2 using UV/VUV. The presence of cyanobacterial cells impeded MC-LR degradation; however, 90% MC-LR degradation could still be achieved. UV/VUV is a promising chemical-free technology capable of MC-LR degradation in a variety of water conditions, and a potentially suitable treatment option for small, remote communities. 

Advanced oxidation; Cyanotoxin; Microcystin-LR; Photolysis; Ultraviolet; Alkalinity; Chlorine compounds; Photolysis; Advanced oxidation; Cyanobacterial cells; Cyanotoxins; Direct photolysis; Microcystin-LR; Remote communities; Ultraviolet; Water conditions; Water treatment; chloride; drinking water; hydroxyl radical; microcystin LR; microcystin; microcystin LR; cell component; concentration (composition); cyanobacterium; degradation; hydroxyl radical; oxidation; photolysis; pollutant removal; toxin; ultraviolet radiation; absorption; Article; bacterial cell; concentration (parameter); controlled study; cyanobacterium; degradation; oxidation; photolysis; quantum yield; rate constant; ultraviolet radiation; water supply; water treatment; eutrophication; lake; radiation response; water pollutant; Cyanobacteria; Kobus; Eutrophication; Lakes; Microcystins; Photolysis; Ultraviolet Rays; Water Pollutants