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411.
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Sari Vilhunen Heikki Särkkä Mika Sillanpää 《Environmental science and pollution research international》2009,16(4):439-442
Background, aim, and scope The novel system of ultraviolet light-emitting diodes (UV LEDs) was studied in water disinfection. Conventional UV lamps,
like mercury vapor lamp, consume much energy and are considered to be problem waste after use. UV LEDs are energy efficient
and free of toxicants. This study showed the suitability of LEDs in disinfection and provided information of the effect of
two emitted wavelengths and different test mediums to Escherichia coli destruction.
Materials and methods Common laboratory strain of E. coli (K12) was used and the effects of two emitted wavelengths (269 and 276 nm) were investigated with two photolytic batch reactors
both including ten LEDs. The effects of test medium were examined with ultrapure water, nutrient and water, and nutrient and
water with humic acids.
Results Efficiency of reactors was almost the same even though the one emitting higher wavelength had doubled optical power compared
to the other. Therefore, the effect of wavelength was evident and the radiation emitted at 269 nm was more powerful. Also,
the impact of background was studied and noticed to have only slight deteriorating effect. In the 5-min experiment, the bacterial
reduction of three to four log colony-forming units (CFU) per cubic centimeter was achieved, in all cases.
Discussion When turbidity of the test medium was greater, part of the UV radiation was spent on the absorption and reactions with extra
substances on liquid. Humic acids can also coat the bacteria reducing the sensitivity of the cells to UV light. The lower
wavelength was distinctly more efficient when the optical power is considered, even though the difference of wavelengths was
small. The reason presumably is the greater absorption of DNA causing more efficient bacterial breakage.
Conclusions UV LEDs were efficient in E. coli destruction, even if LEDs were considered to have rather low optical power. The effect of wavelengths was noticeable but
the test medium did not have much impact.
Recommendations and perspectives This study found UV LEDs to be an optimal method for bacterial disinfection. The emitted wavelength was found to be an essential
factor when using LEDs; thus, care should be taken in selecting the proper LED for maximum disinfection. 相似文献
413.
采用分光光度法对工业总排放水中Cr6+进行不确定度评定,充分考虑测量重复性、标准溶液的配制、标准曲线的制备等因素对测量的影响,测得Cr6+的合成标准不确定度为0.023mg/L。 相似文献
414.
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417.
程丹 《环境监测管理与技术》2007,19(3):54-55
吸附处理是红外法测定石油类的一个重要环节.通过实验对吸附柱法和振荡吸附法进行对较,结果表明动植物油质量浓度为0.560 mg/L~145 mg/L的水样,振荡吸附法吸附效率高于吸附柱法.振荡吸附法还具有操作时间短、硅酸镁耗量低、对操作人员危害性小、样品可批量分析的优点. 相似文献
418.
溴酸钾氧化氨基黑10B催化光度法测定痕量亚硝酸根 总被引:4,自引:0,他引:4
研究了在磷酸介质中 ,痕量亚硝酸根对溴酸钾氧化氨基黑 1 0 B的催化褪色作用 ,建立了催化动力学光度法测定痕量亚硝酸根的新方法 ,并探讨了动力学反应条件 ,方法的线性范围为 0~ 1μg/1 0 ml,检出限为 4.88× 1 0 - 9g/ml,用于地面水及雨水中亚硝酸根的测定 ,结果满意。 相似文献
419.
在柠檬酸介质中,I-对KIO3氧化结晶紫的反应有催化效应,据此建立了测定微量I-新的催化动力学光度法.方法的检出限为0.185μg/ml,测定范围为5~70μg/25ml,用本法对环境水样进行了测定,结果满意。 相似文献
420.
火焰原子吸收分光光度法测定生活垃圾堆肥产品中铅 总被引:1,自引:2,他引:1
曹杰山 《环境监测管理与技术》2007,19(6):28-30
建立了硝酸-氢氟酸-高氯酸消解、火焰原子吸收分光光度法测定生活垃圾堆肥产品中铅的方法,试验了不同消解体系和共存离子对测定的影响.方法线性良好,检出限为20 mg/kg(按称取0.5 g试样消解定容至50 mL计算),对不同地域堆肥产品测定的RSD为2.6%~8.7%,加标回收率为89.0%~107%. 相似文献