Sensitized Photooxidation of Dissolved Sulfides in Water

by T. F. Brewer, Univ of Nevada, Reno, United States,
J. G. Curtis, Univ of Nevada, Reno, United States,
E. A. Marchand, Univ of Nevada, Reno, United States,
V. D. Adams, Univ of Nevada, Reno, United States,
E. J. Middlebrooks, Univ of Nevada, Reno, United States,

Document Type: Proceeding Paper

Part of: Critical Issues in Water and Wastewater Treatment


The ability of methylene blue (MB) and riboflavin (RF) to sensitize dissolved sulfides for photooxidation was investigated. Both MB and RF were found to be effective sensitizers for the oxidation of sulfide in water. MB-dosed batch reactors consistently reduced initial sulfide concentrations of 100 mg/l to less than 10-15 mg/l in less than one hour under artificial lighting (91% sunlight corrected fluorescent tubes) at a pH=10 and MB=1mg/l. Preliminary experiments have shown that approximately 80-85% of the removed sulfide is accounted for as accumulated sulfate. RF is also effective at enhancing the removal of sulfide, but experiments similar to those conducted for MB revealed that RF-dosed reactors required approximately 2-3 times longer to achieve sulfide removal comparable to MB (1 mg/l), even with an RF concentration of 20 mg/l. The primary product in RF-sensitized photooxidation of dissolved sulfides is also sulfate, with approximately 75-80% of removed sulfide recovered as sulfate. First order plots of experimental data yield reaction rate constants of k=0.0097 min-1 for RF, and k=0.0273 min-1 for MB.

Subject Headings: Sulfides | Sulfates | Oxidation | Water treatment | Wastewater management | Light (artificial) | Groundwater quality

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