Plasma-induced Degradation of Chlorobenzene in Aqueous Solution

Liquid-phase degradation of chlorobenzene (CB), induced by contact glow discharge electrolysis under various reaction conditions, such as, the initial solution pH, current intensity, volume of solution and iron salts was investigated. Experimental results indicated that, in the absence of catalysts, the depletion of CB followed first-order kinetics, where the observed value of the first-order rate constant ‘k’ is directly proportional to the applied current intensity and inversely proportional to the solution volume. Initial solution pH had little effect on the value of k. HPLC and IC analyses showed that the major intermediate products were chlorophenols, phenol, organic acids and chloride ions. During the treatment, a lot of hydrogen peroxide was formed. Role of Fenton’s reaction was examined. A reaction pathway is proposed based on the degradation kinetics and the distribution of intermediate products.     

烟道气组成的快速测定

将Porapak柱、Chromosorb P柱及5A分子筛柱串联后再并联,构成一个无阀切换的二维色谱,用于测定烟道气组成;一次进样就可分析烟道气中一氧化碳、二氧化碳和氧气等组分,该法具有分析速度快、重复性好、准确度高的特点,有较大的实用价值。     

A semi-empirical Henry's law expression for carbon dioxide dissolution in ionic liquids

A simple model was developed to predict the solubility of carbon dioxide (CO₂) in ionic liquids under normal processing and conditioning pressures for natural gas fluids. COSMO-RS was used to predict the unsymmetrical activity coefficients for CO₂ in ILs, and the Peng-Robinson equation of state was used to calculate the CO₂ fugacity coefficient. Using these two quantities, a correlation was developed which can be used to extrapolate solubilities for ILs where experimental data is not available. This study shows that the molecular mass of the ILs is an effective parameter to correlate the Henry's constant of CO₂.     

Efficient Degradation of Nitrobenzene Induced by Glow Discharge Plasma in Aqueous Solution

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     

Atmospheric Pressure RF (13.56 MHz) Glow Discharge: Characterization and Application to “In Line” Waste Water Treatment

In this work the results obtained from the experimental study of an Atmospheric Pressure Glow Discharge (APGD) appear, generated in Helium (He) and dry air mixture by using a radio frequency (RF 13.56 MHz) power source. The external conditions of the discharge, its macroscopic parameters (i.e., electronic number density n_e and temperature T_e) and the results of its application to in line industrial and domestic waste water treatment are presented.     

One-Step Hydroxylation of Benzene to Phenol Induced by Glow Discharge Plasma in an Aqueous Solution

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.     

Application of Dielectric Barrier Discharge Reactor Immersed in Wastewater to the Oxidative Degradation of Organic Contaminant

Dielectric barrier discharge (DBD) is an effective method available for the production of ozone and ultraviolet light. The wastewater treatment system of this study was designed to utilize both ozone and ultraviolet light produced in the DBD reactor for the degradation of organic contaminant. The DBD reactor consisted of a quartz cylinder and a coaxial ceramic tube inside of which a steel rod was placed. The DBD reactor was immersed in the wastewater that was grounded. In this case, the wastewater acted not only as an electrode but also as the cooling medium for the DBD reactor. An azo dye, Acid Red 27, was used as the organic contaminant. In this system, the organic contaminant was degraded by two oxidation pathways induced by ozone and ultraviolet light. The concentration of ozone, the ultraviolet radiation intensity and the degradation efficiency of the organic contaminant were measured by varying the discharge. The results showed that the present system was very effective for the degradation of the organic contaminant. The energy requirement for the degradation was found to be 0.654 kJ/mg, which is much smaller value than those obtained with an ultraviolet/photocatalytic process.     

烟气中还原SO2到单质硫的催化剂

文章综述了目前研究开发的适用于烟气脱硫过程中还原SO2为单质硫的各种催化剂,对其组成,结构,性能及催化机理作了描述,并对今后的研究和发展方向提出了若干建议。     

Torrefaction in the Presence of Oxygen and Carbon Dioxide: The Effect on Yield of Oil Palm Kernel Shell

Torrefaction refers to a thermochemical treatment that reduces the moisture content of biomass and increases its energy density by removing water and lower energy volatiles. Torrefaction process requires mild treatment temperature between 200 to 300 ˚C in the absence of oxygen (inert atmosphere). Through torrefaction, biomass transformed into a char-like solid with higher value than the raw biomass. Industries found it applicable for the torrefied biomass to be co-fired with coal in power plants because of the close similarity in properties. The torrefied biomass can also be used as feedstock for entrained-flow gasifier, or for residential heating. During torrefaction, a continuous supply of nitrogen to create the needed inert state incurs certain cash flow to the torrefaction plant; meanwhile the nitrogen price is depending on the volatile prices of natural gas that is currently suffered from depletion. The alternative of this problem is to utilize flue gas as a replacement of the nitrogen in parallel with the fact that nitrogen is a major composition of flue gas. A fundamental study is needed to support the idea, for that reason this paper studied how the behaviour of torrefaction diverged when the process was carried out in the presence of oxygen and carbon dioxide. The chosen biomass is oil palm kernel shell (PKS) due to its abundance in Malaysia. The torrefactionis carried out 250 ˚C for30 min. In comparison to the solid yield of torrefied PKS in inert torrefaction, the solid yield in oxygen and carbon dioxidetorrefactionis practically unaffected by the non-inert gases. Liquid yield is almost similar in each torrefactioncondition;however the gas yield in carbon dioxide torrefaction is produced intensely compared to the gas yield in oxygen torrefaction.     

面向环境应用的超重力反应器强化技术:从理论到工业化

工业酸性气体是造成环境污染的最主要因素之一.本文围绕国家环保超低排放新要求,提出了超重力反应强化理论原理和新途径,利用超重力反应器数量级强化传质和超短停留时间优势,高选择性地从混合酸性气体中反应脱除SO2、H2S或CO2,实现了硫化物超低排放;提出了"科学实验+微观机理模型+宏观CFD模拟"三位一体的超重力反应器放大方法,实现了超重力反应器的工程放大,研制出国际规模最大的超重力反应器(转子直径3.5 m、外壳5 m,气体处理量20×104 m3/h)并投入产业化应用;该强化新技术现已在工业尾气脱SO2、石油炼厂气和海洋天然气脱H2S、电厂烟气脱CO2等环保工程中实现了工业应用和推广.     

玻璃纤维表面的乙烯基单体接枝聚合

用玻璃纤维表面处理剂ＭＡＣ处理玻璃纤维后，再进行臭氧处理，使玻璃纤维的表面产生活性中心，引发苯乙烯、甲基丙烯酸甲酯、及丙烯酸等乙烯基单体在玻璃纤维表面上接枝聚合。接枝纤维的密度减小，对水的浸润性下降，红外光谱及扫描电镜观察证明玻璃纤维表面上接枝聚合物的存在。     

Degradation of organic dyes in water by electrical discharges

The degradation of several organic compounds in aqueous solution: methyl yellow (C₁₄H₁₅N₃), methyl red (C₁₅H₁₅N₃O₂), methyl orange (C₁₄H₁₄N₃NaO₃S), phenol red (C₁₉H₁₄O₅S) and methylene blue (C₁₆H₁₈ClN₃S), was investigated in a pulsed corona discharge. High voltage pulses of 17 kV amplitude, 24 ns rise time and approximately 200 ns duration (full width at half maximum––FWHM) were applied to an array of six hollow needles. When oxygen was bubbled into the solution through the needle, current pulses of 90 A amplitude were obtained and the average power dissipated in the discharge was 19 W at 100 Hz pulse repetition rate. UV-visible spectra of the aqueous solutions show a significant reduction of the absorbance in the visible range, up to 90%, after plasma treatment, suggesting fragmentation of the compounds. Several aliphatic compounds were identified as oxidation products of methyl yellow, methyl red and methyl orange. For methylene blue and phenol red aromatic reaction products were detected as well.     

Sensitive electrochemical detection of ozone

An amperometric sensor capable of detecting ozone in the low ppb range was developed. The most suitable electrochemical cell was based on a gold-Nafion electrode with 0.5 M H₂SO₄ as internal electrolyte solution. It is demonstrated, that by careful selection of the experimental conditions such as electrode materials, electrolyte solution and applied potential the determination of low concentrations of ozone in air is possible with detection limits of 0.6 ppb. Cross-sensitivities to the major inorganic gaseous species found in the atmosphere, are also presented, and the use of a chemical filter to circumvent the interference by nitrogen dioxide is described.     

Porous sol gel silica films doped with crystalline NiO nanoparticles for gas sensing applications

A reliable sol gel route to synthesize NiO doped SiO₂ films with different NiO content is here described. The films showed detectable and reversible changes in both optical and electrical properties when exposed to some reducing/oxidizing gaseous species at temperatures in the 250°C–350°C range. A functional characterization protocol has been designed and some of the sensing properties of the materials have been investigated for detecting NO₂, CH₄, CO and H₂. An optical transmittance increase up to 2% has been detected for 1% CO in dry air atmospheres, while relative resistance response (R _R = R _gas/R _air) values up to 4.97 for 850 ppm H₂/air mixtures have been registered for conductometric gas sensing. Films at all NiO molar concentrations in the 10% NiO - 40% range showed an optical response to the target gas, while only 30% and 40% NiO films provided a detectable gas induced resistance change.     

Continuous measurement of metals in flue gas using ICP-OES

A system capable of continuously measuring a range of metallic elements in the effluent gas from incinerators and other similar industrial processes, and providing on-line results has been developed. With a state-of-the-art mobile laboratory measurements were taken from a UK municipal solid waste incinerator. The detection system used was an ICP-OES, with a modified torch to allow the introduction of flue gas directly into the plasma. Metals that were investigated were Ni, Hg, V, Al, Na, Ca, Cu, Sn, Pb, Sb, As, Cd and Tl, with limits of detection in the range 0.0004 mg m^–3 to 0.1 mg m^–3 being calculated. Emission measurements produced data that showed that the MSWI plants emission were significantly lower than the emission limits specified in EC 2000/76/EC.     

多壁碳纳米管负载TiO2的光催化脱硝性能

采用溶胶凝胶法制备了多壁碳纳米管负载TiO₂ （MWCNTs/TiO₂）,并利用透射电镜、X射线光电子能谱、X射线衍射和紫外-可见漫反射光谱对样品进行了表征。结果表明,MWCNTs/TiO₂晶型以锐钛矿为主,MWCNTs的引入会限制TiO₂晶粒的生长。另外,MWCNTs/TiO₂的光吸收边向长波区域偏移。针对模拟烟气,在固定床光催化反应器中对采用涂覆处理的MWCNTs/TiO₂的光催化脱硝性能进行了实验研究。结果表明,NO初始浓度较低时,光催化脱硝效率较高,SO₂的存在可抑制光催化脱硝过程,而O₂及H₂O则有促进作用。在最佳实验条件（73 mg/m³ NO,8% O₂,5% H₂O）下,光催化脱硝效率可达46%。提出了光催化脱硝反应机理。     

Degradation of microporous polyaniline film by UV-ozone treatment

Thin microporous polyaniline films in the emeraldine-base form (PANI-EB) have been prepared electrochemically at a potential of 0.8 V. The effect of ozone treatment on the structural changes of polyaniline thin films has been investigated using X-ray photoelectron spectroscopy, SEM and EPR. Surface analysis showed that oxidation occurs mainly at the carbon atoms, resulting in the formation of CO and COOH species. The degradation reaction seems to be preferentially directed towards the quinoneimine units. At high extent of carbon oxidation, UV-ozone treatment may involve the direct oxidation of the nitrogen atoms to form -NO_x species.