Pulsed Ultraviolet Light Emitting Diodes for Advanced Oxidation of Tartrazine.

摘要

A study was conducted to evaluate the advanced oxidation of organic contaminants using pulsed ultraviolet light emitted diode (UV LED). Tartrazine was used as a surrogate organic compound. Low pressure Mercury-based lamps currently used in the treatment of water pose potential health risks if broken and create final disposal issues at the end of their service life. UV LED offers an alternative solution due to its non-toxicity, flexible design, and longer operating life compared to the mercury-based lamps. The apparent first order reaction rate constant for tartrazine degradation increased linearly with increasing duty cycle. At a continuous 100% duty cycle, tartrazine degraded by18% after 5 hours of operation. When normalized to power output, the lower duty cycles exhibited greater rate constants. The 5% duty cycle produced a normalized rate constant 100% greater than those observed at 20% and higher duty cycles. Reduced LED power output with time was not observed. As an anionic compound, it is believed tartrazine sorption to the LED surface was not occurring. Believed to be due to incomplete reactor mix, the experimental results show increased data noise at duty cycles 20% and greater. When the reactor was equipped with a mechanical mixing device, the data scatter was considerably reduced. Root square mean, R2, significantly improved from 0.57- 0.96 range for non-stirred reactor to 0.70 - 0.99 range for stirred reactor between 5% to 100% duty cycles.