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11.
以新烟碱类杀虫剂呋虫胺为目标污染物,以过硫酸钾为氧化剂,研究不同热活化条件下过硫酸钾对呋虫胺降解率的影响。实验结果表明:呋虫胺的降解率与溶液中过硫酸钾的浓度成正比;随着温度的升高,呋虫胺的降解率也逐渐升高;虽然中性时呋虫胺的降解率稍高于酸性和碱性时的降解率,但pH的变化对呋虫胺的降解率影响不大;Cl-和HCO3-对反应的影响比较复杂,当溶液中的Cl-和HCO3-的浓度低于5 mmol/L时,均促进呋虫胺的降解,而浓度升高时则抑制呋虫胺的降解;通过添加自由基捕获剂发现,该反应体系中同时存在·SO4-和·OH,但起主要作用的是·SO4-。 相似文献
12.
负载型颗粒活性炭催化过硫酸钠氧化降解橙黄G 总被引:1,自引:0,他引:1
通过在颗粒活性炭(GAC)上负载氧化铁,并以此作为催化剂(Fe/GAC)在常温常压下催化过硫酸钠(PS)产生硫酸根自由基降解偶氮染料橙黄G。研究了体系pH、氧化剂浓度、催化剂浓度对橙黄G去除率的影响,并且对催化剂的重复使用性能进行了测试。结果表明,在Fe/GAC/PS体系中,[OG]0=0.2 mmol/L,[GAC]=1 g/L,[PS]0=2 mmol/L,降解2 h后OG去除率为99%,且有较高的矿化率;随着氧化剂浓度和催化剂浓度的增加,OG的去除效率提高;催化剂有较好的重复使用性。利用扫描电镜(SEM)对催化剂进行了表征,可以看出在活性炭上成功负载氧化铁。利用化学分子探针竞争实验鉴定催化反应中的活性物种SO4-·和OH·。 相似文献
13.
Takayuki Kameda Koji Inazu Yoshiharu Hisamatsu Norimichi Takenaka Hiroshi Bandow 《Atmospheric environment (Oxford, England : 1994)》2006,40(40):7742-7751
The formation of mutagenic nitro-polycyclic aromatic hydrocarbons (NPAHs) 1- and 2-nitrotriphenylene (1- and 2-NTP) via gas-phase OH or NO3 radical-initiated reactions of triphenylene was demonstrated for the first time using a flow reaction system. In contrast with the results of conventional electrophilic nitration, 2-NTP was formed in larger yield than 1-NTP, but this is consistent with the mechanism proposed for gas-phase radical-initiated nitration of PAH. In diesel exhaust particle (DEP) samples, both 1- and 2-NTP were identified and their concentrations determined, as well as 1-nitropyrene (1-NP), which is a representative combustion-derived NPAH: the mean concentrations of 1-NTP, 2-NTP, and 1-NP were 4.7, 1.9, and 32 pmol mgDEP–1, respectively. The mean 2-NTP/1-NTP, 1-NTP/1-NP, and 2-NTP/1-NP ratios in samples of airborne particles collected in a residential area in Osaka, Japan, were>1.55,<0.25, and 0.37, respectively; these values are much higher than those of the DEP samples. This finding indicates that there is another source for airborne NTPs, especially 2-NTP, apart from diesel exhaust. These results strongly suggest that airborne NTPs originate from atmospheric processes such as radical-initiated reactions of triphenylene, and this has a significant influence on the atmospheric occurrence of NTPs. 相似文献
14.
The anticancer drugs: adriamycin, farmorubicin and mitomycin C greatly enhance the generation of hydroxyl radicals (HO.) from H2O2 in the presence of Co(II) ions (CoCl2) at pH 7.4 and 8, as measured by the deoxyribose assay. Catalase, hydroxyl radical scavengers (mannitol, cysteine, glutathione, thiourea, lactic dehydrogenase) inhibited the degradation of deoxyribose confirming that HO‐radicals are responsible for the degradation of the carbohydrate. 相似文献
15.
Formation of N-nitrosodimethylamine (NDMA) by ozonation of dyes and related compounds 总被引:1,自引:0,他引:1
Formation of N-nitrosodimethylamine (NDMA) by ozonation of commercially available dyes and related compounds was investigated. Ozonation was conducted using a semi-batch type reactor, and ozone concentration in gas phase and the ozone gas flow were 10 mg L(-1) and 1.0 L min(-1), respectively. NDMA was formed by 15 min of ozonation of seven out of eight selected target compounds (0.05 mM) at pH 7. All the target compounds with N,N-dimethylamino functions were NDMA precursors in ozonation. The lowest and highest NDMA concentrations after ozonation of the target compounds were 13 ng L(-1) for N,N-dimethylformamide (DMF) and 1600 ng L(-1) for N,N-dimethyl-p-phenylenediamine (DMPD), respectively. NDMA concentrations after 15 min of ozonation of 0.05 mM methylene blue (MB) and DMPD increased with an increase in pH in its range of 6-8. The effects of coexisting compounds on NDMA concentrations after 15 min of ozonation of 0.05 mM MB and DMPD were examined at pH 7. NDMA concentrations after ozonation of MB and DMPD increased by the presence of 0.05 mM (0.7 mg L(-1) as N) nitrite (NO(2)(-)); 5000 ng L(-1) for MB and 4000 ng L(-1) for DMPD. NDMA concentration after MB ozonation decreased by the presence of 5mM tertiary butyl alcohol (TBA), a hydroxyl radical (HO.) scavenger, but that after DMPD ozonation was increased by the presence of TBA. NDMA concentrations after ozonation of MB and DMPD were not affected by the presence of 0.16 mM (5.3 mg L(-1)) hydrogen peroxide (H(2)O(2)). When 0.05 mM MB and DMPD were added to the Yodo and Tone river water samples, NDMA concentrations after 15 min of their ozonation at pH 7 increased compared with those in the case of addition to ultrapure water samples. 相似文献
16.
Chengyuan SU Weiguang LI Xingzhe LIU Xiaofei HUANG Xiaodan YU 《Frontiers of Environmental Science & Engineering》2016,10(1):37-45
A study of the decolorization of reactive brilliant blue in an aqueous solution using Fe-Mn-sepiolite as a heterogeneous Fenton-like catalyst has been performed. The Fourier transform infrared (FTIR) spectra of the catalyst showed bending vibrations of the Fe-O. The X-ray diffraction (XRD) patterns of the catalyst showed characteristic diffraction peaks of α-Fe2O3, γ-Fe2O3 and MnO. A four factor central composite design (CCD) coupled with response surface methodology (RSM) was applied to evaluate and optimize the important variables (catalyst addition, hydrogen peroxide dosage, initial pH value and initial dye concentration). When the reaction conditions were catalyst dosage= 0.4 g, [H2O2]= 0.3 mL, pH= 2.5, [reactive brilliant blue]o = 50 mg·L−1, and volume of solution= 500 mL at room temperature, the decolorization efficiency of reactive brilliant blue was 91.98% within 60 min. Moreover, the Fe-Mn-sepiolite catalyst had good stability for the degradation of reactive brilliant blue even after six cycles. Leaching of iron ions (<0.4 mg·L−1) was observed. The decoloring process was reactive brilliant blue specific via a redox reaction. The benzene ring and naphthalene ring were first oxidized to open ring; these were then oxidized to the alcohol and carboxylic acid. The reactive brilliant blue was decomposed mainly by the attack of ·OH radicals including surface-bound ·OH radicals generated on the catalyst surface. 相似文献
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18.
为进一步认识La(Ⅲ)提高类黄酮含量及减轻UV-B辐射伤害植物机制,以大豆幼苗为材料,采用水培实验的方法研究了La(Ⅲ)对UV-B辐射胁迫下大豆幼苗类黄酮抗氧化能力的动态影响.结果表明, UV-B辐射(T1:0.15W·m-2和T2:0.45W·m-2)胁迫下,大豆幼苗类黄酮含量在胁迫期和恢复期均先升后降,质膜透性、MDA含量先升(1~5d)后降(6~11d),类黄酮对O·-2和·OH的清除率与其含量变化趋势近同.各处理组类黄酮含量La(Ⅲ) UV-B>UV-B>La(Ⅲ)>CK, La(Ⅲ) T1>La(Ⅲ) T2;质膜透性、MDA含量UV-B>La(Ⅲ) UV-B>CK>La(Ⅲ), La(Ⅲ) T2>La(Ⅲ) T1;类黄酮对O-2和·OH清除率La(Ⅲ) UV-B>UV-B>La(Ⅲ)>CK, La(Ⅲ) T1, La(Ⅲ) T2,表明La(Ⅲ)对类黄酮的调控作用,提高了清除活性氧自由基的运行效率,降低了MDA浓度,维持了质膜正常透性,且对低剂量(T1)的防护效果优于高剂量(T2),进而在防御系统层面实现了La(Ⅲ)对UV-B辐射伤害大豆幼苗的防护效应. 相似文献
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20.
Ren Shufen Zhang Xuelin Li Wencheng Wang Wensheng Wang Jin Wang Wenjun Zhang Yuxia 《环境科学学报(英文版)》1991,3(4):95-101
The humic acid contents in drinking water and soil in Kaschin-Beck disease areas were found more than that of non-disease areas in this research. Changes of free radical concentration in drinking water were agreed with that of humic acid contents in drinking water of Kaschin-Beck disease areas. A positive correlation of free radical concentration and humic acid content in drinking water has been shown (r=0.913) . The structure of I. R. spectra of humic acid under ultraviolet light has been changed. Thus it indicated that free radical was resulted from benzoqiunonyl groups of humic acid in environment. 相似文献