CHEMICAL ENGINEERING JOURNAL
·
2018
·
IF 6.735
Mantang Chen,Zhimin Zhang,Lihua Zhu,Nan Wang,Heqing Tang
The present work aimed at using bisulfites (HSO 3 − ) to enhance the oxidative degradation of bisphenol A (BPA) in a Fenton process based on the Fe 3+ -H 2 O 2 reagents. It was confirmed that both the degradation and mineralization of BPA were drastically enhanced by the addition of HSO 3 − . Typically, the use of 0.1 mmol L −1 Fe 3+ , 0.3 mmol L −1 HSO 3 − and 10 mmol L −1 H 2 O 2 achieved a complete degradation of BPA (0.05 mmol L −1 ) in only 2 min. The addition of HSO 3 − increased the BPA degradation rate constant from 0.045 min −1 in the Fe 3+ -H 2 O 2 system to 2.71 min −1 in the Fe 3+ -HSO 3 − -H 2 O 2 system by 60 times. This drastic enhancement effect of HSO 3 − was attributed to its complexing and reducing abilities. The formation of FeSO 3 + complex prevented the precipitation of Fe 3+ and accelerated the cycling of Fe 3+ /Fe 2+ ; the reducing ability of HSO 3 − further favored the transformation of Fe 3+ to Fe 2+ . Several reactive species, including OH, SO 3 − and SO 4 − were responsible for the degradation of BPA, among which OH was the dominant one. The proposed Fe 3+ -HSO 3 − -H 2 O 2 system is suggested be able to act as the followed stage of a traditional Fe 2+ -H 2 O 2 system in the engineering setting.
研究领域:
环境科学
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化学工程
·
污染控制
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF MOLECULAR CATALYSIS A-CHEMICAL
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2016
·
IF 3.958
Lei Zhao,Baoyue Zhang,Xin Xiao,Feng Long Gu,Rui-Qin Zhang
Active species such as holes, electrons, hydroxyl radicals ( OH), and superoxide radical anions ( O 2 − ) involved in the photocatalytic oxidation of benzyl alcohol (BA) into benzaldehyde (BAD) on TiO 2 under ultraviolet (UV) light were investigated by adding corresponding scavengers. The experimental results show that the oxidation of BA into BAD is driven mainly by the holes and OH radical. The role of dissolved O 2 was studied by bubbling N 2 through the reaction. The results show that the dissolved O 2 is, to some extent, the source of OH. Additional density functional theory (DFT) calculations identified two H-abstraction pathways ( R abs OH and R abs α). The structure of the R abs OH product is less stable and tends to transfer resulting in the R abs α product. The holes are the main driving force for the abstracting of H from BA. The OH radical combines with the H-abstract product to form a precursor of product BAD, detected by LC–MS technique ( m / z 123), which then undergoes an intramolecular dehydration reaction to form BAD. The results will help to select the optimal active species for the photocatalytic oxidation of BA into BAD on TiO 2 under UV light.
研究领域:
物理化学
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光催化
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环境化学
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材料化学
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理论计算化学
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DOI
高影响因子
WATER AIR AND SOIL POLLUTION
·
2019
·Vol. 230
·期 2
·41
·
IF 1.774
Wang Wanfeng,Liang Fang,Guo Yanling,Wu Ruijie,Pan Feng,Jin Caixia,Wang Jun
Since nitrosamine disinfection by products is highly carcinogenic, they have attracted considerable attention due to their increased presence in ambient waterways and potable water supplies. For the present study, the potential formation of nitrosamines from corresponding precursor secondary amines during ozonation was investigated. The results revealed that five nitrosamines were observed during the ozonation of their corresponding secondary amines. The molar yields initially increased and then decreased with longer contact times and higher ozone doses. These phenomena indicated that ozone not only promoted nitrosamine formation but also degraded the formed nitrosamines. High pH had a positive influence on nitrosamine formation at room temperature. Further, coexisting substances including nitrate, nitrite, humic acid, and tert-butanol inhibited the generation of nitrosamines due to hydroxyl radical (·OH) competition and scavengers, whereas in the presence of hydroxylamine, nitrosamine formation increased considerably without ozone due to its capacity for independent formation between secondary amines and hydroxylamine. Further, the generation of nitrosamines from secondary amines was primarily attributed to O 3 and ·OH oxidation, which was produced through the decomposition of ozone. The transformation pathways were mainly comprised of the indirect routes between the O 3 /·OH intermediates. The findings of this study were helpful toward expanding the knowledge of nitrosamine formation during the corresponding precursor secondary amine ozonation process.
研究领域:
环境科学
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水处理化学
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污染物转化
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消毒副产物
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氧化过程
✓ 已验证
DOI
高影响因子
RSC Advances
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2016
·Vol. 6
·期 110
·108791-108800
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IF 3.289
Wei Zhou,Haiqian Zhao,Jihui Gao,Xiaoxiao Meng,Shaohua Wu,Yukun Qin
The Fenton system (Fe2+/H2O2) generates ·OH with a high oxidation potential. However, as reactants themselves, H2O2 and Fe2+ can act as ·OH initiators as well as ·OH scavengers, leading to the need for a high dosage of reactants and increased costs. As a mixing-sensitive reaction, the ·OH-related reaction kinetics (·OH with Fe2+, H2O2, and RhB) was determined from the reaction rates (which were a constant in this work) and stoichiometry, in which the latter could be regulated by an addition strategy of Fenton reagents. This suggests that ·OH competitive reactions could be controlled by applying a macrolevel addition strategy. Herein, the effects of different addition approaches of Fe2+ and H2O2 on ·OH competitive reactions were quantitatively and systematically studied by analyzing the removal of the model pollutant RhB. We found that without stirring, and compared with a one-time addition, once H2O2 or Fe2+ was added in a step-wise pattern (e.g., one drop by one drop, 2 times, or 4 times), a high concentration of H2O2 or Fe2+ existed in a localized place for a longer period, resulting in a lower proportion of ·OH reacting with RhB, which we ascribed to an enhanced reaction between Fe2+, H2O2, and ·OH. However, when H2O2 and Fe2+ were added from two close points without stirring, a larger proportion of ·OH was scavenged by H2O2 and Fe2+; while under stirring, even a one-time addition of H2O2 or Fe2+ could cause severe scavenging of ·OH. The results also revealed a linear relationship between the RhB removal percentage and wavelength blue-shifts. This study showed that microlevel ·OH competitive reactions could be controlled by applying a macrolevel addition strategy of Fenton reagents without the addition of external chemicals. The results suggest this methodology can also offer an approach to lower ·OH invalid consumption by regulating the addition strategy in bigger reactors.
研究领域:
环境化学
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水处理技术
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高级氧化过程
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反应动力学
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污染控制化学
✓ 已验证
DOI
高影响因子
危险品化学品经营许可证（带存储）