苯酚苯胺共聚物在304不锈钢电极表面的电化学合成及成膜微观结构分析

苯酚和苯胺在304不锈钢阳极表面实现了电化学共聚,反应在中性水溶液中进行,电解质为硫酸钠. 比较不同苯酚苯胺浓度下共聚成膜耐点蚀能力,当苯酚为0.09 mol/L和苯胺为0.01 mol/L时最佳.红外光谱分析证实苯胺结构出现在苯酚苯胺的共聚物中,且共聚物膜比聚苯酚膜含有更多支链. 利用苯酚苯胺共聚物膜在四氢呋喃中的部分溶解性,使用扫描电子显微镜分析四氢呋喃清洗前后的成膜,观察到网状聚苯胺结构. 将共聚物膜与聚苯酚膜微观结构进行推测和比较,解释在电聚合反应中适量加入苯胺能提升成膜防腐能力原因.     

光助Fenton法降解水中间氨基苯酚的研究

采用光助Fenton氧化法处理间氨基苯酚模拟废水,考察了光强、Fenton试剂的用量、初始pH、反应时间对降解效果的影响,初步探讨了其降解动力学规律。结果表明:在不同光源下(闭光、高压汞灯照射以及较强太阳光照射),450W高压汞灯照射以及较强太阳光照射的条件均可以明显加快Fenton法催化氧化降解间氨基苯酚溶液的过程。选择1.5mL2.5g.L-1FeSO4.7H2O,1.0mL6%H2O2,初始pH=3.5,太阳光照射下降解间氨基苯酚效果较好,反应40min后降解率高达99%;降解过程符合准一级反应动力学方程。     

比值-导数法同时测定污水中的苯酚和苯胺

根据苯酚和苯胺在紫外区均有吸收的特点 ,建立了用比值 导数法同时测定苯酚和苯胺的紫外分光光度法。该法对波谱重叠严重的苯酚和苯胺类化合物能进行有效测定 ,省去了萃取、蒸馏、显色、酸化等预处理步骤 ,具有能消除背景干扰、提高灵敏度及提高速度的优点。在优化实验条件后进行苯酚和苯胺的测定 ,它们的线性范围分别为 1 0 1～ 2 4 2 4mg·L- 1 和 1 0 1～ 2 4 2 9mg·L- 1 ,其检测限分别为 0 0 97和 0 6 85mg·L- 1 。对合成样进行分析时 ,苯酚和苯胺的相对标准偏差 (RSD)分别为 2 6 0 %和 2 16 % ,标准加入的回收率在 95 %～ 10 4 %之间 ,结果良好。对污染河水水样进行分析测定 ,并进行加标回收试验 ,平均回收率在91%～ 10 8%之间     

苯酚和苯胺类化合物对光泽精化学发光的增强和抑制作用

研究了苯酚和苯胺类化合物在不同pH下对光泽精-H2O2-Co2 体系化学发光(Chemiluminescence,CL)的影响.在NaHCO3-Na2CO3缓冲体系中,具有吸电子基团或两个-OH处于间位的化合物在中间的pH(即pH 9.9)呈现增强作用,其他的化合物呈现抑制作用;在NaOH体系中,所有的化合物都呈现抑制作用.化合物对光泽精CL增强和抑制作用与化合物的结构、介质、以及介质的pH有关.通过研究光泽精CL反应混合物的荧光光谱以及光泽精体系的CL光谱等,提出了其增强和抑制作用的可能机理.苯酚和苯胺类化合物与光泽精竞争消耗溶液中的H2O2/HO-2,导致了化合物对光泽精CL的抑制作用;同时,苯酚和苯胺类化合物可以作为亲核试剂与光泽精反应形成一种加成物,这种加成物与光泽精相互作用生成光泽精自由基,然后与溶解氧反应产生CL,从而增强光泽精的CL.这两种作用相互竞争,导致了不同的条件下,化合物对光泽精CL增强和抑制作用的出现.     

等离子体制取羟自由基降解苯酚溶液及其历程的UV研究

研究了利用强电离放电产生等离子体方法制取羟基自由基氧化降解高浓度苯酚废水。当羟基自由基浓度达到1 037 mg.L-1时,初始浓度为1 215 mg.L-1的废水降解率达99.11%;初始浓度为8 853 mg.L-1的废水苯酚浓度下降到6 250 mg.L-1,1 mg羟基自由基可处理苯酚2.5 mg。在同样羟自由基浓度下,苯酚初始浓度越小,去除率越高;但初始浓度越高,处理的绝对量越大。阐述并解释了不同降解阶段废水pH值、电导率与羟基自由基浓度变化的关系。随着羟自由基浓度的增大,废水酸碱性由接近中性逐渐转为酸性,浓度越大,酸性越强;继续增大羟自由基浓度,变化渐趋平缓。随着羟自由基的通入,电导率有一个微小的降低阶段然后开始上升,说明苯酚不断的被氧化为有机酸。通过紫外图谱和色谱分析了降解中间产物,表明氧化初始阶段邻苯二酚、对苯二酚和苯醌是其中重要的化合物。     

直接热氧化制备氧化钛薄膜电极的研究Ⅱ.光电性能

采用电化学阻抗谱和光电响应等手段对在光照下热氧化制备的氧化钛膜的阻抗和光电性质进行了研究 .结果表明 ,随氧化温度升高 ,界面电荷转移电阻减小 ,光电流逐渐增大 ,苯胺的光电催化速率降解增大 .温度大于6 0 0℃后 ,电极的光电性能急剧降低 .热氧化制备的氧化钛膜电极的结构、界面电荷转移电阻、光电流和光电催化降解苯胺的速率之间存在良好的相关性     

铁掺杂A-TiO_2光催化降解对硝基苯酚的动力学研究

研究了以自制掺铁的锐钛矿型TiO2(即A-TiO2)光催化降解对硝基苯酚的动力学过程。结果表明:在可见光照射下,对硝基苯酚溶液为20mg·L-1、溶液调节为酸性(pH=2)、自制的掺铁0.1%(摩尔分数)A-TiO2的投入量1.0g·L-1、室温下搅拌下反应200min的条件下,对硝基苯酚的光催化降解的表观反应速率常数k(0.0050min-1)和降解率(64.52%)最大,拟合可见光下铁掺杂TiO2降解对硝基苯酚为一级反应。     

卡尔曼滤波分光光度法同时测定炼油废水中苯酚和苯胺的研究

用卡尔曼滤波紫外分光光度法同时测定了模拟炼油废水中苯酚和苯胺的含量 ,取得了满意的结果。苯酚和苯胺的回收率分别为 99.0 %—— 10 3.8%和 97.8%—— 10 0 .6 %。     

外电场下4-氟苯酚分子的分子结构和解离特性

4-氟苯酚是一种用途广泛的芳香族化合物,同时也是具有毒性的有机污染物之一,对环境和人体都有巨大危害.研究其在外电场作用下的降解机理具有重要意义.本文采用密度泛函方法(DFT)方法和含时密度泛方法(TD-DFT)在B3LYP/6-311G+(2d, 2p)基组水平上,研究了4-氟苯酚分子在不同外加电场(0-0.03 a.u.)下的几何结构、光谱特性、解离特性.结果表明,外加电场对4-氟苯酚分子的结构和性质有较大影响,随着X(C-F键)方向外电场的增加,4-氟苯酚分子C-F键的键长增大、分子体系总能量逐渐减小、偶极矩逐渐增大、能隙逐渐减小. 4-氟苯酚分子红外光谱的最强峰发生红移,紫外吸收光谱吸收峰峰值先增大后减小,峰型变宽,4-氟苯酚分子解离势能逐渐减小,说明4-氟苯酚分子在外电场作用下趋于解离.该研究对4-氟苯酚污染物分子的外电场降解提供参考.     

离散小波变换-独立成分回归稳键模型的研究

在波长200-400nm范围内,研究苯酚、苯胺和苯甲酸的光谱行为.采用离散小波变换(DWT)对光谱数据进行处理,独立成分回归(ICR)方法建模,建立了离散小波变换-独立成分回归(DWT-ICR)稳健模型.方法用于模拟样品中苯酚、苯胺和苯甲酸的测定,结果满意.     

Effect of irradiation distance on degradation of phenol using indirect ultrasonic irradiation method

Ultrasound is used as degradation of hazardous organic compounds. In this study, indirect ultrasonic irradiation method was applied to the degradation process of phenol, the model hazardous organic compound, and the effects of irradiation distance on radical generation and ultrasonic power were investigated. The chemical effect estimated by KI oxidation dosimetry and ultrasonic power measured by calorimetry fluctuated for the irradiation distance, and there was a relationship between the period of the fluctuation of ultrasonic effect and the wavelength of ultrasound. The degradation of phenol was considered to progress in the zero-order kinetics, before the decomposition conversion was less than 25%. Therefore, the simple kinetic model on degradation of phenol was proposed, and there was a linear relation in the degradation rate constant of phenol and the ultrasonic power inside the reactor. In addition, the kinetic model proposed in this study was applied to the former study. There was a linear relation in the degradation rate constant of phenol and ultrasonic energy in the range of frequency of 20-30 kHz in spite of the difference of equipment and sample volume. On the other hand, the degradation rate constant in the range of frequency of 200-800 kHz was much larger than that of 20-30 kHz in the same ultrasonic energy, and this behaviour was agreed with the former investigation about the dependence of ultrasonic frequency on chemical effect.     

Influence of La2O3 on the Thermal Stability of Polybenzoxazine: Effect of Substituted Groups

Four kinds of benzoxazine monomers were synthesized, using phenol and aniline, 4-methylaniline, 4-nitroaniline, or 3-nitroaniline as starting materials. La₂O₃ was incorporated into the benzoxazines to prepare polybenzoxazine composites. The polybenzoxazines and their composites were analyzed through Fourier transform infrared (FTIR), thermogravimetric analysis (TGA), and TGA–FTIR. The results revealed that La₂O₃ can improve the thermal stability of aniline-based polybenzoxazine (Pa) and 4-methylaniline-based polybenzoxazine (Pa-pC) due to the delay of evaporation of the amine compounds during their thermal degradation process. However, La₂O₃ did not influence the thermal stability of polybenzoxazines based on 4-nitroaniline (Pa-pN) or 3-nitroaniline (Pa-mN), mainly resulting from the introduction of the nitro group remarkably changing the thermal degradation processes of Pa-pN and Pa-mN, producing a great deal of CO₂ and H₂O in their degradation gases, while amine and phenolic compounds gases were hardly detected.     

Kinetics of ultrasonic degradation of phenol in the presence of TiO2 particles

The degradation of phenol by ultrasonic irradiation in the presence of TiO2 was investigated in complete darkness. The effects of amount of TiO2 and the combination of TiO2 addition with gas (air or oxygen) supply on the degradation kinetics of phenol and the formation of the reaction products were examined. The degradation rate of phenol increased with the amount of TiO2. As the dissolved oxygen concentration increased by supplying oxygen, the degradation rate of phenol also increased. A kinetic model for the disappearance of phenol was proposed. The model takes into account the OH radical formation by direct water degradation, indirect degradation by oxygen atom and indirect degradation by TiO2 catalysis. The calculated results explained well the fact that a higher amount of TiO2 and dissolved oxygen concentration gave faster disappearance rate.     

Flow effects on phenol degradation and sonoluminescence at different ultrasonic frequencies

Current literature shows a direct correlation between the sonochemical (SC) process of iodide oxidation and the degradation of phenol solution. This implies phenol degradation occurs primarily via oxidisation at the bubble surface. There is no work at present which considers the effect of fluid flow on the degradation process. In this work, parametric analysis of the degradation of 0.1 mM phenol solution and iodide dosimetry under flow conditions was undertaken to determine the effect of flow. Frequencies of 44, 300 and 1000 kHz and flow rates of 0, 24, 228 and 626 mL/min were applied with variation of power input, air concentration, and surface stabilisation. Phenol degradation was analysed using the 4-aminoantipyrine (4-AAP) method, and sonoluminescence (SL) images were evaluated for 0.1, 20 and 60 mM phenol solutions. Flow, at all frequencies under certain conditions, could augment phenol degradation. At 300 kHz there was excellent correlation between phenol degradation and dosimetry indicating a SC process, here flow acted to increase bubble transience, fragmentation and radical transfer to solution. At 300 kHz, although oxidation is the primary phenol degradation mechanism, it is limited, attributed to degradation intermediates which reduce OH radical availability and bubble collapse intensity. For 44 and 1000 kHz there was poor correlation between the two SC processes. At 44 kHz (0.01 mM), there was little to suggest high levels of intermediate production, therefore it was theorised that under more transient bubble conditions additional pyrolytic degradation occurs inside the bubbles via diffusion/nanodroplet injection mechanisms. At 1000 kHz, phenol degradation was maximised above all other systems attributed to increased numbers of active bubbles combined with the nature of the ultrasonic field. SL quenching, by phenol, was reduced in flow systems for the 20 and 60 mM phenol solutions. Here, where the standing wave field was reinforced, and bubble localisation increased, flow and the intrinsic properties of phenol acted to reduce coalescence/clustering. Further, at these higher concentrations, and in flow conditions, the accumulation of volatile phenol degradation products inside the bubbles are likely reduced leading to an increase SL.     

Kinetics and mechanism for the oxidation of anilines by ClO2: a combined experimental and computational study

The oxidation of para‐substituted anilines (X–C₆H₄NH₂, X = –CH₃, –H, –Cl, –NO₂) with chlorine dioxide was studied as a means of eliminating these pollutants. The oxidation rate decreases from that for 4‐methylaniline to that for 4‐nitroanilinem in agreement with the Hammett plot; the oxidation kinetics is second order in aniline and first order in ClO₂, for which a possible mechanism is proposed. Liquid chromatography and gas chromatography mass spectrometry results show that benzoquinone is formed as the major intermediate in aniline/ClO₂ oxidation, and the reaction is pH‐dependent as the rate constant increases with increasing pH. To further support our proposed mechanism, Density Functional Theory (DFT) computations at both B3LYP/6‐311 + G(d,p) level with the polarizable continuum model with an integral equation formalism solvation model (i.e., with water) were carried out, showing that activation energy barriers predict the same reactivity trend as shown by the kinetics experiments. Copyright © 2014 John Wiley & Sons, Ltd.     

Effect of additives on ultrasonic degradation of phenol

Sonication for phenol degradation has proved to be an attractive process over the years at least on a laboratory scale but the rates of phenol degradation under sonication have always been quite low. The present work investigates the use of simple additives such as salt and carbon tetrachloride as process intensifying parameters with an aim of reduction in the treatment times and hence the cost of operation. The intermediates formed in the degradation process have been analyzed and it has been observed that these intermediates degrade faster as compared to phenol. A hybrid technique of ozonation coupled with cavitation has also been investigated with an objective of finding the optimum conditions for the combination of ozonation and cavitation for synergistic effects. Analysis of the intermediates for the combination treatment scheme also indicates that the intermediates (hydroquinone, catechol, resorcinol, maleic acid, acetic acid, oxalic acid, formic acid, etc.) are more biodegradable prompting a possible combination of cavitation with aerobic oxidation for large scale treatment of phenol containing waste.     

A combination of ultrasound and oxidative enzyme: sono-enzyme degradation of phenols in a mixture

Sono-degradation and sono-enzyme degradation of phenols were performed on the mixtures of double compounds (phenol, p-chlorophenol; phenol, p-cresol; phenol, p-nitrophenol; and p-chlorophenol, p-cresol) in aqueous medium. Sono-degradation of phenol and its substituted compounds individually behaved approximately the same, but in the case of mixture behaved differently. Sono-degradation of substituted phenols was easier than phenol in a mixture, but there was an exception in the combination of phenol and p-nitrophenol that the degradation of phenol was faster than substituted compound. This behavior was the same in sono-enzyme degradation, but with higher degradation rate. Between these mixtures, the combination of phenol and p-cresol presented a significant different behavior in case of single and double compounds solutions. In this system, the sono-degradation of phenol in mixture was more difficult than phenol alone but, the sono-degradation of p-cresol in mixture was easier in comparison with p-cresol alone. In sono-enzyme degradation, p-cresol as a more reactive compound facilitated the remove of phenol in mixture in compare of the individual case.     

Performance of different crystal structures of PbO2 on electrochemical degradation of phenol in aqueous solution

Phenol degradation was carried out in acidic aqueous solution on different crystal structures of PbO₂ surfaces at room temperature. Phenol, benzoquinone and maleic acid concentrations were monitored during the electrolysis process. It was determined that β surfaces have higher performance than surfaces on phenol degradation. Then, the effect of crystallinities of pure β-PbO₂ surfaces was investigated and found that higher crystallinity increased the efficiency of the phenol degradation process.