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1.
The oxidative degradation of nitrobenzene (NB) induced by gaseous glow discharge plasma in contact with aqueous solution was investigated.
The experimental results indicated that NB removal obeyed first-order kinetics under certain applied currents. The major degradation
byproducts such as nitrophenols, phenol, 1,3-dinitrobenzene and carboxylic acids have been detected. The distribution of nitrophenols
follows the order o- > p- > m- and oxalic, formic and acetic acids are major carboxylic intermediates. The eventual products were nitrate ion and carbon
dioxide. During the treatment, a large amount of hydrogen peroxide was produced. Addition of ferrous or ferric ions into the
solution greatly enhanced the degradation rate due to Fenton’s reaction. The energy efficiencies of NB removal and hydrogen peroxide formation were compared with those of other discharges. Hydroxyl radicals were shown
to be the most likely species responsible for NB degradation 相似文献
2.
Kinetics and Mechanism of the Organic Degradation in Aqueous Solution Irradiated with Gaseous Plasma 总被引:1,自引:0,他引:1
The degradation of organic compounds in an aqueous solution induced by a gaseous plasma, which was sustained locally on the
surface of solution by means of contact glow discharge electrolysis, was mechanistically studied. The oxidation of phenol
was extensively examined and it was revealed that the rate of disappearance followed the first-order rate law when the initial
concentration of phenol was lower than 100 mM. As the initial concentration increased, the rate equation gradually deviated
from the first-order and eventually shifted to zero-order above 250 mM. Such a kinetical behavior could be rationalized by
assuming the reaction scheme where hydroxyl radical would act as the most responsible key-species for the organic degradation
in competition with the coupling to hydrogen peroxide. In addition, the catalytic effects of Fe ions in the solution on the
rate of organic degradation were closely investigated and could be consistently explained on the above concept. 相似文献
3.
Xi Kui WANG* Guan Hong CHEN Zhong Yan YAO College of Chemistry Environmental Science University of Jinan Jinan 《中国化学快报》2003,14(2):205-208
Ultrasonic waves in a liquid induce the formation of cavitation bubbles. Submitted to an oscillating pressure field, cavities filled with vapor and dissolved gas pulsate, grow and implode violently when they reach a critical resonant size. According to the 慼ot spot?theory, extremely high temperature and pressure are produced during the collapse of cavitation bubbles1. Under these extreme conditions, the molecules vaporized in the bubbles as well as in the surrounding condensed layer could … 相似文献
4.
YUEBin JIANGLei HUChang-wen CHENJian-min HEHe-yong 《高等学校化学研究》2005,21(4):386-390
Paratungstate-loaded titania catalysts were prepared via the addition of a series of aqueous solutions of paratungstate( denoted as W7 ) into an isopropanol solution of Ti[ OCH( CH3 )2 ]4 by means of the sol-gel method. The catalysts were characterized by EDX, BET, FTIR, UV-Vis DRS, XRD and the results indicate that such paratungstateloaded catalysts maintained their heptatungstate structure in the anatase titania matrix up to 400℃. The catalysts were tested for the heterogeneous photodegradation of chlorobenzene in aqueous media and showed a better catalytic activity than P-25 TiO2 because paratungstate can prevent the recombination of the holes and electrons produced during irradiation. Moreover, the paratungstate-loaded titania catalysts can resist the disaggregation during the photoirradiation and can be easily recycled from the aqueous suspensions after reactions. 相似文献
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L. R. Grabowski E. M. van Veldhuizen A. J. M. Pemen W. R. Rutgers 《Plasma Chemistry and Plasma Processing》2006,26(1):3-17
A small batch reactor is developed to study the removal of phenol from a thin layer of water by creating pulsed corona discharges
above the water. Pulses of up to 40 kV are applied with a duration of ~50 ns and an energy of ~60 mJ. In this CAW (Corona
Above Water) reactor an ozone yield of upto 90 g/kWh is obtained in ambient air. The phenol degradation is 48 g/kWh, using
a 1 mM initial concentration in demineralized water. The degradation yield increases to almost 100 g/kWh by adding to the
water either H2O2 or Fe2SO4 or NaOH. The first two additions are considered to increase to amount of OH radicals. In the case of NaOH addition it is
observed that much more ozone dissolves in the water. The addition of the OH scavenger t-butanol shows that in most cases
the main oxidation route of phenol in the CAW reactor is direct ozone attack. 相似文献
8.
Direct phenol synthesis from benzene in aqueous solution where water was used as the oxidant through glow discharge plasma
(GDP) process was described for the first time. The effect of pH, ferrous and cupric ions on the phenol yield and selectivity
was examined. Phenol yield of 8.3% and selectivity of 81% has been achieved. 相似文献
9.
一种水处理的新方法:金属卟啉和空气存在下光催化降解亚甲基蓝水溶液 总被引:1,自引:0,他引:1
在450W高压汞灯照射及聚对苯二磺酰氧基苯基卟啉钴存在下,考察了亚甲基蓝降解过程中紫外-可见吸收光谱的变化,研究了空气光催化降解亚甲基蓝水溶液反应的动力学.实验结果表明,亚甲基蓝可迅速降解,并且符合一级动力学过程,其表观动力学常数K=0.35435 h-1,半衰期t1/2=1.96 h.经光催化降解后,亚甲基蓝水溶液脱色率可达57.4%;其COD浓度降低43.1%.太阳光具有与高压汞灯相似的作用,这为以金属卟啉作光敏剂进行太阳能转化、贮能提供很大的应用潜能.光催化剂具有较好的光稳定性,可回收利用,而且反应结束后可自动沉降,避免二次污染.初步实验结果表明,该方法是一种具有应用前景的水处理方法. 相似文献
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Plasma-induced deposition of wear-protecting A12O3 films has been investigated for two different gas mixtures, one of which is ususally used in thermal CVD. It is shown that, contrary to thermal CVO, the properties of thin films deposited from an AlCl3/O2/Ar mixture are superior to those prepared from AICl3/CO2/H2. High Vickers hardness of 1800-2500 and a low chlorine content of 0.7 at. % have been obtained in films deposited from an AICl3/O2/Ar mixture at a substrate temperature of 500°C. 相似文献
12.
Chao Feng Xianghua She Yequan Xiao Yanbo Li 《Angewandte Chemie (International ed. in English)》2023,62(9):e202218738
In situ detection of highly-oxidized metal intermediates is the key to identifying the active center of an oxygen evolution reaction (OER) catalyst, but it remains challenging for NiFe-based catalysts in an aqueous solution under working conditions. Here, by utilizing the dynamic stability of the FeVIO42− intermediates in a self-healing water oxidation cycle of NiFe-based catalyst, the highly-oxidized FeVI intermediates leached into the electrolyte are directly detected by simple spectroelectrochemistry. Our results provide direct evidence that Fe is the active center in NiFe-based OER catalysts. Furthermore, it is revealed that the incorporation of Co into NiFe-based catalyst facilitates the formation of FeVI active species, thus enhancing the OER activity of NiCoFe-based catalyst. The insights into the mechanisms for the sustainable generation of FeVI active species in these NiFe-based catalysts lay the foundation for the design of more efficient and stable OER catalysts. 相似文献
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In this study, the response surface methodology was first applied to optimize the photocatalytic degradation of styrene in aqueous phase under UV/TiO2 system. Twenty experiments were done by adjusting three parameters (styrene concentration, TiO2 dose, and pH) at five levels. Optimal experimental conditions for arbitrary aqueous styrene concentration (115 mg L?1) were found: initial pH 7 and TiO2 loading 2 g L?1 with photocatalytic degradation efficiency of 79.2%. Furthermore, the main degradation intermediate produced was identified by GC/MS. The total organic carbon results revealed that the photocatalysis process could be effectively mineralized. Kinetics of the photocatalytic reaction followed a pseudo-first-order model. 相似文献
15.
Oxidative Degradation of Aqueous Cresols Induced by Gaseous Plasma with Contact Glow Discharge Electrolysis 总被引:2,自引:0,他引:2
The oxidative degradation of cresols smoothly proceeded toward inorganic end products when a gaseous plasma generated by means
of dc glow discharge was sustained in contact with the surface of aqueous solution containing organic compounds. In order
to get mechanistic insight, the monohydroxylation products from each isomeric cresol were closely examined as primary intermediates
to reveal that the aromatic hydroxylation preferentially occurred at the position para to the hydroxyl group of each starting
material. It was also established that the degradation of cresols strictly followed the first-order rate law. On the basis
of the orientational analysis and the kinetical consideration including the effects of Fe ions added on the reaction rate,
it was concluded that hydroxyl radical, which might result from the homolytic cleavage of water molecules by the action of
plasma, was the most likely reagent responsible for the mineralization of cresols. 相似文献
16.
The degradation of poly(hydroxyethyl methacrylate), PHEMA obtained by γ -radiation induced polymerization of HEMA in aqueous solution, was studied. The polymer was a gel type and insoluble in common organic solvents. The DSC thermogram of the polymer gave a Tg value at 88.2°C and an endothermic peak showed further polymerization or crosslinking at 110–160°C. The degradation observed in TGA was a depolymerization type. However, the FT-IR of TGA fragments showed no monomer, which was degraded further. The degradation of monomer was studied by the GC-MS method. Similar results were also observed. 相似文献
17.
液相辉光放电原子发射光谱法测定溶液中Cd的方法研究 总被引:1,自引:0,他引:1
通过改进放电装置,建立了一种新的液相辉光放电原子发射光谱(LGD-AES)测量溶液中Cd元素的方法。探索了放电电压和Cd浓度对放电稳定性、光谱信号强度、测定灵敏度和检出限的影响,并将测试结果与电解液阴极放电-原子发射光谱(ELCAD-AES)的分析结果进行比较。结果表明,当放电电压从600V升至720 V时,电子温度从2 000 K升至3 300 K,电子密度从2.47×10~(16)cm~(-3)降至1.77×10~(16)cm~(-3),Cd的发射光谱强度增强,灵敏度升高,检出限为1.22~2.95 mg/L。LGD-AES技术检测水中金属离子具有放电设备小型、能量消耗低、放电稳定性高、背景光谱干扰小和灵敏度高等优点。 相似文献
18.
利用高温高压一步法合成系列Al Mn-复合柱化剂,该方法的步骤、物料消耗等较传统制备方法均大大减少,可大大降低生产成本及减少对环境的污染。通过离子交换合成系列Al Mn复合柱撑粘土(Al Mn-PILC)。改变Al/Mn摩尔比、老化温度、老化时间,可调控Al Mn-复合柱化剂的结构,从而影响Al Mn-PILC的结构性能(包括比表面积、孔体积、孔径、层间距等)。通过XRD,N2吸附,高分辨电镜及程序升温还原等实验对材料的结构及性能进行了表征。结果表明:经550℃焙烧4 h后,Al Mn-PILC的比表面积和孔体积可达174.2~246.7 m2·g-1和0.126~0.158 cm3·g-1,层间距可达1.85 nm。经柱撑改性合成的Al Mn-PILC,其负载Cr Ce催化剂对氯苯的催化降解性能远高于原土(Nammt)和单核Al-PILC的,尤其以Cr Ce(9∶1)/Al Mn-PILC的催化活性最佳,在250℃时可完全降解低浓度的氯苯,是一类性能优异的用于有机物催化降解的多孔材料。 相似文献
19.
J. H. Yan Ch. M. Du X. D. Li B. G. Cheron M. J. Ni K. F. Cen 《Plasma Chemistry and Plasma Processing》2006,26(1):31-41
The efficiency of a gliding arc reactor designed with the aim to degrade aqueous phenol solutions is studied as a function
of supply voltage, electrode gap distance, and gas–liquid flow properties. This efficiency, which steeply increases when increasing
the supply voltage, can reach 96% when the minimum electrode distance is fixed at 3 mm. Experiments show that phenol degradation
efficiency also depends on solution pH, Fe2+ addition, gas nature and gas flow rate. Furthermore, degradation pathways of phenol in aqueous solutions are proposed. 相似文献
20.
Bi Tao SU Shi Xiong SHE Shi Xiong MIN Zhan Ying MA 《中国化学快报》2005,16(10):1361-1363
A new property of conjugated polymer poly(furancarbinol-co-phenol)(PFP) was studied. The target copolymer was used as a catalyst after proper heating treatment. And dye methylene blue (MB) could be fully degraded and largely mineralized on PFP, under natural light or even in dark, in a few minutes. Furthermore, the catalytic activity could be preserved after several runs and the catalyst was readily separated. The effect of calcination temperature was also observed. 相似文献