紫外-活性炭协同活化过硫酸氢钾对罗丹明B的降解
Degradation of Rhodamine B by peroxymonosulfate synergistically activated by UV/activated carbon
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摘要: 利用紫外光（UV）和活性炭（AC）协同活化过硫酸氢钾（PMS）产生硫酸根自由基（SO4-·）对染料进行降解.以罗丹明B（RhB）作为目标污染物，考察了PMS浓度、AC用量、废水初始pH等因素对体系降解RhB的影响.实验表明，UV-AC体系能有效活化PMS.AC用量0.5 g· L-1，PMS浓度为2.0 mmol· L-1时，10 mg· L-1RhB的降解率在5 min达到89%，RhB的降解率随着初始PMS浓度和AC的用量增加而增大，但超过一定量时，对降解的促进就不明显.降解反应遵循准一级动力学.自由基清除的实验证明了硫酸根自由基（SO4-·）是主要的活性自由基，羟基自由基（HO·）也起到一定的作用，同时证明UV对PMS活化的贡献大于AC.通过紫外可见光谱和FT-IR光谱分析，初步推断RhB分子降解主要是由于共轭结构裂解和N-位脱乙基等作用.五次循环实验后RhB的脱色率仍能达到85%证明了降解体系的稳定性.Abstract: Synergistic activation of peroxymonosulfate (PMS) by ultraviolet (UV) and activated carbon (AC) produces sulfate radicals (SO4-·) to degrade dyes. Rhodamine B (RhB) was used as a target pollutant. The effects of PMS concentration, AC dosage, and initial pH of the wastewater on the degradation of RhB were investigated. Experiments showed that UV/AC combination effectively activated PMS. When the AC was dosage 0.5 g·L-1, PMS concentration 2.0 mmol·L-1, the degradation rate of 10 mg·L-1RhB reached 89% in 5 minutes.The degradation rate increased with the increase of initial PMS concentration and AC consumption. But when it exceeded a certain amount, the promotion of degradation was not obvious. The degradation reaction followed Quasi-first-order kinetics.Free radical scavenging experiment proved that sulfate radical (SO4-·) was the main active radical, and hydroxyl radical (HO·) also played a certain role. At the same time, it was proved that the contribution of UV to PMS activation was greater than AC. Through UV-visible spectroscopy and FT-IR spectroscopy, it was preliminarily inferred that the degradation of RhB molecules was mainly due to the effects of conjugated structure cleavage and N-position deethylation. After five cycles of experiments, the decolorization rate of RhB still reached 85%, which proved the stability of the degradation system.
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Key words:
- UV light /
- activated carbon /
- peroxymonosulfate /
- Rhodamine B /
- sulfate radical
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