Comparative Actions of NiO and TiO<Subscript>2</Subscript> Catalysts on the Destruction of Phenol and its Derivatives in a Dielectric Barrier Discharge

This study examined processes of decomposing phenol and its derivatives (resorcin, pyrocatechol and hydroquinone) in aqueous solutions under the action of an atmospheric pressure oxygen dielectric barrier discharge in the presence or absence of catalysts in the plasma zone. Two types of catalysts were tested, NiO and TiO₂. It was found that both materials exhibited catalytic properties. The action of NiO accelerated the step of phenol destruction while the action of TiO₂ catalyst resulted in a more preferable composition of decomposition products and provided a higher degree of carboxylic acid conversion into carbon dioxide than the NiO catalyst.     

A Study of Sulfonol Decomposition in Water Solutions Under the Action of Dielectric Barrier Discharge in the Presence of Different Heterogeneous Catalysts

The decomposition kinetics of sulfonol (surfactant) in water solutions as well as the formation kinetics of decomposition products under the action of an oxygen dielectric barrier discharge (DBD) at atmospheric pressure in the presence or absence of TiO₂, NiO and Ag₂O catalysts in the plasma zone was studied. The DBD discharge was shown to have high decomposition efficiency (phenol-up to 98%, sulfonol-up to 80%). In a plasma-catalytic hybrid process, the efficiency of organic substances decomposition was higher than efficiency for the DBD treatment without catalyst. The catalysts application resulted in a change in the ratio and yield of decomposition products.     

Carbon-supported manganese for heterogeneous activation of peroxymonosulfate for the decomposition of phenol in aqueous solutions

Phenolic substances are harmful to humans and other living things, even at low concentrations. Therefore, phenol must be removed from water with the proper process. One of the most effective processes for degrading phenol is heterogeneous catalytic oxidation. Three carbon materials as supports were used to prepare manganese-oxide based catalyst (2.5% MnOx/ACP and 2.5% MnOx/ACN), and graphene oxide (2.5% MnOx/GO). These catalysts were tested for the degradation of phenol in aqueous solution using peroxymonosulfate as a source of sulfate radical. The physio-chemical catalysts were characterised by several characterisation techniques such as powder X-ray diffraction, N₂-sorption (BET), scanning electron microscopy (SEM) equipped with Dispersive Energy X-ray Spectroscopy (EDS). In comparison to other catalysts, heterogeneous activation of peroxymonosulfate was more effectively done by 2.5% MnOx/ACP, resulting in a higher production rate of sulfate radicals. In the presence of a catalyst at 0.2 g and 1 g peroxymonosulfate in 500 mL solution at 25 °C, 90% total organic carbon (TOC) removal and phenol decomposition of 100% was achieved in 90 min with phenol concentration of 75 mg/L. First-order kinetics were followed by phenol decomposition with the energy of activation on 2.5% MnOx/ACP of 15.0 kJ/mol.     

Combined Plasma-Induced and Catalytic Decomposition of Phenols

Decomposition of phenol and its derivatives, resorcinol and pyrocatechol, was studied in barrier-discharge plasma in the presence of substances exhibiting catalytic properties.     

Destruction of 2,4-Dichlorophenol in Water Solution Using a Combined Process of Sorption and Plasma Exposure to DBD

The results of studies of the decomposition of 2,4-dichlorophenol (2,4-DCP) in its aqueous solution under the action of atmospheric pressure DBD in an oxygen flow are presented. A new reactor design was used in which the discharge zone was filled with a sorbent (diatomite). It was found that the kinetics of decomposition obeys a first-order kinetic equation for the concentration of 2,4-DCP. The presence of an adsorbent significantly improves the parameters of the decomposition process. Decomposition rates, rate constants and energy efficiency are doubled. So, at a specific discharge power of 1.8 W/cm³ in the presence of a sorbent, the rate constant was ~1 s^?1, and without it, ~0.5 s^?1. The energy efficiency was 0.031 and 0.016 molecules per 100 eV, respectively. The parameters of the treated solution are improved in terms of its potential toxicity. The concentrations of the main decomposition products (aldehydes, carboxylic acids) in the presence of a sorbent are significantly less than without it. This is due to an increase in the rate of conversion of these products into carbon dioxide molecules. It was also shown that the decomposition of one 2,4-DCP molecule leads to the formation of two chloride ions in solution, and the ozone formed in the discharge does not significantly affect the destruction process.

     

Removal of Oil Products from Water Using a Combined Process of Sorption and Plasma Exposure to DBD

The paper presents the results of studies of a combined process involving the sorption of engine oil on a sorbent (diatomite) followed by regeneration of the sorbent by plasma-oxidative destruction of oil in DBD of atmospheric pressure in oxygen. The process parameters (gas flow rate, sorbent mass, power, treatment time), which provide the possibility of fivefold regeneration of the sorbent and 100% degree of oil decomposition, are revealed. It was found that the kinetics of oil degradation obeys the pseudo-first kinetic order equation with a rate constant of 0.017 s^?1. The energy efficiency of the decomposition was 0.169 molecules of oil per 100 eV of input energy. It is shown that treatment of the sorbent for 5 min leads to the complete decomposition of oil. The products of oil decomposition are carboxylic acids, aldehydes and CO₂. Complete removal of acids and aldehydes requires the time of about 40 min. The possible participation of ozone in the oxidative degradation of oil is discussed.     

Decomposition of Toluene and Acetone in Packed Dielectric Barrier Discharge Reactors

The influences of TiO₂ catalytic material and glass pellet packing on the decomposition efficiency of toluene and acetone in air by dielectric barrier discharge (DBD) reactors were experimentally investigated in this study. The effects of both packing materials on the formation of byproducts such as CO and CO₂ were also evaluated. Experimental results indicate that the introduction of glass materials into the plasma zone of a wire-tube reactor would improve the decomposition efficiency of toluene and acetone compared to a nonpacked reactor. The apparent decomposition rate constant of a glass packed-bed reactor was 4.5–4.8 times greater than that of a nonpacked reactor. The results also indicate that the decomposition rate constant of toluene was approximately 2.6 times higher than that of acetone no matter which type reactor was utilized. The application of TiO₂ coated pellets in DBD reactors will enforce the hydrocarbon byproducts to further be oxidized to CO₂, notwithstanding, it will not significantly improve the performance of the reactors in the decomposition of toluene and acetone, and in the formation of CO. The results show that the best selectivity of CO₂ for acetone decomposition in a TiO₂ coated pellets packed-bed reactor was approximately 40% higher than that in a glass packed-bed reactor.     

Application of Dielectric Barrier Discharge for Waste Water Purification

This study considers treatment of real city rain sewage under the action of an oxygen dielectric barrier discharge (DBD) at atmospheric pressure in the presence or absence of TiO₂ catalyst in the plasma zone. The DBD discharge has been shown to have high decomposition efficiency (up to 98%) for oil hydrocarbons, phenols and synthetic surfactants. The discharge action resulted in the decrease of heavy metal (Pb, Cd, Fe, Mn) content as well. In a plasma-catalytic hybrid process, the efficiency of organic substances decomposition was higher than efficiency for the DBD treatment without catalyst.     

The effect of dosage on the photocatalytic degradation of organic pollutants

Heterogeneous photocatalytic degradation of many organic pollutants, such as phenol and phenol derivatives, may be optimised if the catalyst surface saturation and the appearance and accumulation of non-photocatalytically degradable intermediates is avoided. It has been shown that under certain concentration threshold the highest degradation efficiencies are achieved. Over these concentrations, degradation rates become constant owing to the limited catalyst surface. By the dosage of the contaminant, currently in an aqueous solution, the process may be optimised, thus avoiding the formation of inert intermediates which may be more toxic than the parental compound. The effect of dosage on the photocatalytic degradation of phenol and phenol derivatives, such as salicylic acid and 4-aminophenol has been studied. Comparatively notably higher efficiencies have been obtained compared to those of the high initial single dose experiments (non-dosage), for which high initial concentrations of the organics resulted in the catalysts poisoning. Degussa P-25 and its combination with 13% (w/w) activated carbon, namely AC?TiO₂, have been used as catalysts. Almost complete degradations are achieved at low dosage rates (1–2 pmm/min). At higher dosage rates, different processes such as catalyst poisoning predominate, resulting in lower degradation efficiencies.     

印染污泥的活性炭负载过渡金属化合物非均相催化臭氧化

采用湿式浸渍法,将6种含过渡金属(Cu,Fe,Zn,Ni,Mn,Ce)元素的化合物负载在活性炭（AC）上,制得6种催化剂AC/M(M=Cu,Fe,Zn,Ni,Mn,Ce),在室温条件下,催化臭氧化处理苯酚溶液和印染污泥。 催化剂AC/M通过Boehm滴定、XRD和BET分析进行表征。 苯酚的3种降解方法中,AC/M催化剂的臭氧催化最好,AC/M吸附处理次之,单独臭氧处理的效果最差。 在苯酚的降解处理过程中,AC/M催化臭氧化处理苯酚溶液的效率依次为：AC/Fe＞AC/Zn＞AC/Ni＞AC/Ce＞AC/Cu＞AC/Mn。 AC/M催化剂催化臭氧化效果随溶液pH值的增大而增强。 AC/M催化剂处理印染污泥的效率依次为：AC/Fe＞AC/Zn＞AC/Ce=AC/Ni＞AC/Cu＞AC/Mn,AC/Fe催化臭氧化处理印染污泥可使污泥中有机质含量降低8.17%。     

蒸馏温度对核桃壳生物油馏分组分分布的影响

通过改变蒸馏温度对生物油进行常压蒸馏并将馏分分为油水两相，研究了馏分的组分分布变化。结果表明，在120-300℃随着蒸馏温度的升高，生物油馏出率不断增加；蒸馏温度低于240℃的油相馏分中萘、甲苯等芳烃类化合物和乙酸等羧酸类化合物明显富集，以120℃油相馏分为例，芳烃类和羧酸类化合物的相对含量是生物油原油的13.86倍和3.15倍；当蒸馏温度高于240℃时苯酚、愈创木酚等酚类化合物大量馏出，使得油相馏分的产率明显增加；同时，所获水相馏分中的水分含量皆高于60%，水分的富集效果明显；在馏分中检测到了2-乙基乙酸丁酯和环戊酮等原油中未检测到的组分并且馏分中水分总量高于生物油原油，这些都表明生物油在蒸馏过程中发生了酯化、缩聚等化学反应。通过对油相馏分的组分分布进行分析，发现改变蒸馏温度可以有效富集生物油中的高价值化合物，如苯酚、愈创木酚、4-甲基愈创木酚、4-乙基愈创木酚和4-丙基愈创木酚的相对含量在300℃的油相馏分中分别比生物油提高了109%、160%、84%、53%和444%。     

Catalytic activity of iron-containing polymers in hydroxylation of benzene with hydrogen peroxide

Hydroxylation of benzene with hydrogen peroxide in aqueous acetonitrile at 50°C was studied. The KU-2-8 and KU-1 cation exchangers, and also specially synthesized cation exchangers and phenolformaldehyde resins derived from pyrocatechol and resorcinol, all modified with Fe(III) cations, were used as catalysts. The macrocomplex KU-2-8/Fe³⁺ showed the highest catalytic activity and ensured 32% yield of phenol in 15 min. The formation of phenol depends in a complex fashion on the initial concentration of hydrogen peroxide, content of Fe(III) ions in the polymer, and reaction time.     

Fe2O3/CNT催化湿法H2O2氧化苯酚

通过化学沉积法和热处理得到多壁碳纳米管负载Fe2O3催化剂 Fe2O3/CNT, Fe2O3的负载质量分数约为15.1%,XRD表征显示,负载的Fe2O3存在α和γ这2种晶型。考察了Fe2O3/CNT催化湿式H2O2氧化去除废水中苯酚催化性能,通过苯酚的去除率及反应过程中催化剂活性组分的溶出总量,研究了催化剂制备过程中添加聚乙烯醇对催化剂性能的影响。在苯酚和H2O2初始浓度分别为350和1 500 mg/L、催化剂投加量为1.0 g/L、温度80 ℃条件下,经过240 min的反应,苯酚去除率达100％,COD去除率为86.1％。     

Synthesis of selenium-containing derivatives of <Emphasis Type="Italic">para</Emphasis>-bromopropyl-substituted phenols

The dynamics of changes in the composition of the reaction mixture during the reaction of Na₂SeSO₃ and bromopropyl-substituted phenol in 50% aqueous ethanol and under the conditions of decreasing EtOH concentration in the reaction medium was studied. Convenient methods for the synthesis of 3-(4-hydroxyaryl)propyl selenosulfates and the corresponding diselenides were proposed. Symmetrical and unsymmetrical selenides (derivatives of alkylated phenols and pyrocatechol) were synthesized.     

The Kinetics of Plasma-Induced Degradation of Organic Pollutants in Sewage Water

The processes of treatment of actual surface water and model solutions in a low-temperature dielectric-barrier discharge (DBD) plasma were studied. The general evaluation of the efficiency of the plasma treatment procedure for sewage purification was made, and a conclusion on the reasonability of its use in combination with conventional treatment methods was drawn. Schemes of conversion processes for organic compounds upon DBD treatment of surface water were proposed, and the effective rate constants of corresponding reactions were estimated (for phenol, k = 0.46 × 10^–5 s^–1). It was found that the reaction of oxidation of pollutants in solutions modeling surface runoff occurs in the diffusion region.     

Monodisperse silica nanoparticles coated with gold nanoparticles as a sorbent for the extraction of phenol and dihydroxybenzenes from water samples based on dispersive micro‐solid‐phase extraction: Response surface methodology

A selective and sensitive method was developed based on dispersive micro‐solid‐phase extraction for the extraction of hydroquinone, resorcinol, pyrocatechol and phenol from water samples prior to high‐performance liquid chromatography with UV detection. SiO₂, SiO₂@MPTES, and SiO₂@MPTES@Au nanoparticles (MPTES = 3‐mercaptopropyltriethoxysilane) were synthesized and characterized by scanning electronic microscopy, thermogravimetric analysis, differential thermogravimetric analysis, and infrared spectroscopy. Variables such as the amount of sorbent (mg), pH and ionic strength of sample the solution, the volume of eluent solvent (μL), vortex and ultrasonic times (min) were investigated by Plackett–Burman design. The significant variables optimized by a Box–Behnken design were combined by a desirability function. Under optimized conditions, the calibration graphs of phenol and dihydroxybenzenes were linear in a concentration range of 1–500 μg/L, and with correlation coefficients more than 0.995. The limits of detection for hydroquinone, resorcinol, pyrocatechol, and phenol were 0.54, 0.58, 0.46, and 1.24 μg/L, and the limits of quantification were 1.81, 1.93, 1.54, and 4.23 μg/L, respectively. This procedure was successfully employed to determine target analytes in spiked water samples; the relative mean recoveries ranged from 93.5 to 98.9%.     

Automatic analyzer for highly polar carboxylic acids based on fluorescence derivatization–liquid chromatography

A sensitive, versatile, and reproducible automatic analyzer for highly polar carboxylic acids based on a fluorescence derivatization–liquid chromatography (LC) method was developed. In this method, carboxylic acids were automatically and fluorescently derivatized with 4‐(N,N‐dimethylaminosulfonyl)‐7‐piperazino‐2,1,3‐benzoxadiazole (DBD‐PZ) in the presence of 4‐(4,6‐dimethoxy‐1,3,5‐triazin‐2‐yl)‐4‐methylmorpholinium chloride by adopting a pretreatment program installed in an LC autosampler. All of the DBD‐PZ‐carboxylic acid derivatives were separated on the ODS column within 30 min by gradient elution. The peak of DBD‐PZ did not interfere with the separation and the quantification of all the acids with the exception of lactic acid. From the LC‐MS/MS analysis, we confirmed that lactic acid was converted to an oxytriazinyl derivative, which was further modified with a dimethoxy triazine group of 4‐(4,6‐dimethoxy‐1,3,5‐triazin‐2‐yl)‐4‐methylmorpholinium chloride (DMT‐MM). We detected this oxytriazinyl derivative to quantify lactic acid. The detection limits (signal‐to‐noise ratio = 3) for the examined acids ranged from 0.19 to 1.1 µm , which correspond to 95–550 fmol per injection. The intra‐ and inter‐day precisions of typical, highly polar carboxylic acids were all <9.0%. The developed method was successfully applied to the comprehensive analysis of carboxylic acids in various samples, which included fruit juices, red wine and media from cultured tumor cells. Copyright © 2014 John Wiley & Sons, Ltd.     

Effect of pressure on the efficiency of nickel and nickel-copper catalysts in decomposition of methane

Methane decomposition into hydrogen and nanofibrous carbon in the presence of high-percentage catalysts (70–90)% Ni–(0–20)% Cu–10% Al at a temperature of 948 K and pressures of 1 to 5 atm was studied in order to develop a technology for enrichment of natural gas with hydrogen. It was found that, With an increasing copper content in the catalyst and and with increasing pressure, the average, methane decomposition rate decreases by 10–20% and the catalyst lifetime and the specific yield of hydrogen (mol/mol_Ni+Cu) become (3.8–12) times higher over the catalyst deactivation period. The mechanisms by which the pressure and the copper content of the catalyst affect these process characteristics are discussed.     

Bioamperometric Assay of Phenol Derivatives Using a Laccase–Nafion Composite

Results of using a laccase–Nafion composite for bioamperometric assay of phenol derivatives are presented. Of the compounds studied, only pyrocatechol, dopamine, and 2-amino-4-chlorophenol can be assayed bioamperometrically. The concentration of phenol substrates is determined from the reduction current of enzymic oxidation products at 0.1 V (Ag/AgCl) on a pyrocarbon electrode with the composite and by the oxygen consumption for enzymic oxidation on a Clark electrode with the composite membrane at –0.7 V. The sensitivity of both methods that use composite of the same composition is compared. Kinetic parameters of either electrode are determined. Ways for improving sensitivity of methods intended for assaying phenol derivatives by using laccase-based electrodes are suggested.     

超临界流体干燥法制备TiO2／C纳米粒子及光催化性能

以TiCl4为原料,采用溶胶凝胶法结合超临界流体干燥法(SCFD)制备了纳米级TiO2/C复合光催化剂.以苯酚的光催化降解对所得催化剂的催化活性进行了评价.结果表明,纳米TiO2/C复合粒子与单组分TiO2比较,复合粒子光催化活性高于单组分的TiO2,h苯酚降解率高达975 ％,COD为957%.并用XRD、TEM、 UV-Vis和XPS等手段进行了表征,iO2以锐钛矿型形式存在.比较了不同制备方法制得的TiO2/C复合催化剂,得出超临界干燥法制备的光催化剂具有粒径小,比表面积大,分散性好,光催化活性高等特点.