Oxidation of benzyl alcohols to ketones and aldehydes by O3 process enhanced using high-gravity technology

In this study, a practical process for ozonization of benzyl alcohols to ketones and aldehydes in a rotating packed bed(RPB-O_3) reactor has been developed. Using 1-phenylethanol as a model reactant, the performance of RPB-O_3 process in different solvents has been compared with the commonly used stirred tank reactor(STR-O_3). Ethyl acetate was the optimum solvent for the conversion of 1-phenylenthanol to acetophenone in RPB-O_3 process, with 78% yield after 30 min. In a parallel STR-O_3 experiment, the yield of acetophenone was50%. Other experimental variables, i.e. O_3 concentration, reaction time, high-gravity factor and liquid flow rate were also optimized. The highest yield of acetophenone was obtained using O_3 concentration of 80 mg·L~(-1),reaction time of 30 min, high gravity factor of 40 and liquid flow rate of 120 L·h~(-1). Under the optimized reaction conditions, a series of structurally diverse primary and secondary alcohols was oxidized with(19%–92%) yield.The ozonization mechanism was studied by Electron Paramagnetic Resonance(EPR) spectroscopy, monitoring the radical species formed upon self-decomposition of O_3. The characteristic quadruple peak with the 1:2:2:1 intensity ratio that corresponds to hydroxyl radicals(·OH) was observed in the electron paramagnetic resonance(EPR) spectrum, indicating an indirect oxidation mechanism of alcohols via ·OH radical.     

苯胺生产技术与市场分析

2012年世界苯胺生产能力已超过500万t/a,主要用于生产MDI;我国的苯胺生产厂家约有20多家,总生产能力约为210万t/a.华东地区是我国苯胺的主要生产地,山东、江苏、上海等地的生产规模占据了全国70％～80％的份额.概述了苯胺生产硝化技术、还原技术及催化剂;阐述了国内外苯胺合成技术进展、消费现状与发展预测.随着未来MDI的快速发展,消费结构调整加快.分析国内外市场与发展,对我国苯胺工业发展提出一些建议.     

Studies in mineralization of aqueous aniline using Fenton and wet oxidation (FENTWO) as a hybrid process

A hybrid process for mineralization of aqueous aniline using Fenton and wet oxidation (FENTWO) is studied. It is important to have maximum conversion of ‘N’ atoms from the waste to N₂. The conversion of input ‘N’ atoms in aniline to N₂ was 15% during wet oxidation without the Fenton process and was improved to 50% with the Fenton process. Therefore, a hybrid process of Fenton followed by wet oxidation was studied for mineralization of the aqueous aniline stream. The parameters for the Fenton process were optimized (pH, catalyst, H₂O₂ to catalyst (FeSO₄) ratio, quantity of H₂O₂). The waste obtained after the Fenton process was then treated by wet oxidation for mineralization by having homogeneous CuSO₄ as the catalyst by keeping FeSO₄ therein. This combined catalyst was found to be more effective for the degradation of the intermediates formed in the Fenton process. Wet oxidation (WO) was studied in the temperature range 473–513 K and the oxygen partial pressure range 0.345–1.38 MPa at pH 6.5. The kinetic data was modeled using a power law rate expression in terms of chemical oxygen demand (COD). The optimum temperature for formation of more N₂ gas was found to be 493 K. The treated waste stream was found to contain oxalic acid using HPLC, and NH₄⁺, NO₃^? and NO₂^? ions using ion chromatography analysis. Copyright © 2007 Society of Chemical Industry     

HSB／A^2-O2工艺在苯胺和硝基苯混合废水处理中的应用

采用HSB生物菌剂,适用的微生物固定化技术和A^2-O2工艺治理苯胺、硝基苯混合废水,处理后的废水各项指标达到排放标准。由于无剩余污泥产生,不仅简化了流程,运行成本也降低。     

Degradation of Acid Black 210 by advanced oxidative processes: O3 and O3/UV

Acid Black 210 (AB-210) dye is one of the most black dyes used by the leather industry. In the present work, AB-210 degradation in aqueous solution by ozonation (O₃) and ozonation with ultraviolet (UV) radiation (O₃/UV) was investigated. The effects of pH, initial dye concentration and UV radiation were studied in laboratory scale. Removal was evaluated in terms of residual AB-210 concentration in the treated solution and mineralization efficiency was evaluated by total organic carbon (TOC) analysis. The results indicated that AB-210 is quickly degraded after 15 min but not totally mineralized. It was observed that dye removal of 100% was achieved at pH 3, 7, and 11, while mineralization was found to increase with the pH (55% at pH 11). Concerning UV-C radiation, it enhanced AB-210 degradation at pH 3 but did not reveal any significant effect at pH 7 and 11.     

Degradation of Sulfosalicylic Acid by O3/UV O3/TiO2/UV,and O3/V-O/TiO2 : A Comparative Study

Chemical oxygen demand (COD) removal rates of sulfosalicylic acid (SSal) degraded by three advanced oxidation processes (AOPs): O₃/UV, O₃/TiO₂/UV and O₃/V-O/TiO₂ are compared in this paper. (V = Vanadium). The results show that O₃/V-O/TiO₂ is the most effective process among three AOPs and the order of degradation efficiencies at different pH values is shown as O₃/V-O/TiO₂ > O₃/TiO₂/UV > O₃/UV. For example, at the buffered solution of pH 6.8, the COD removal rate of O₃/V-O/TiO₂ reaches 70% in 30 minutes, but those of O₃/TiO₂/UV and O₃/UV are 55% and 47% at the same conditions, respectively. Furthermore, the effect of CO₃ ^{2 ?}on the COD removal rates of three AOPs shows that O₃/V-O/TiO₂ and O₃/TiO₂/UV may be considerable promising methods to overcome the limitation of the presence of radical scavenger in solution. Both the adsorption of SSal on catalysts and other oxidants (atom oxygen, photo-generated hole) must be responsible for the above result.     

Membrane enhanced COD degradation of pulp wastewater using Cu2O/H2O2 heterogeneous Fenton process

Both activity and stability of the catalyst can be improved in heterogeneous Fenton reaction, in particular, with no limitation for the working pH and no production of the sludge. In this work, a combination of catalyst Cu₂O and pore-channel-dispersed H₂O₂ is proposed to treat the pulp wastewater. Degradation degree of CODs in the wastewater was up to 77% in the ceramic membrane reactor using Cu₂O powder (2.0 g·L^-1) and membranefeeding H₂O₂ (0.8 ml·L^-1) within 60 min. Evolution of ·OH radical formation in the advanced oxidation process was analyzed with a fluorescent method. Utilization efficiency of H₂O₂ was successfully enhanced by 10% with the membrane distributor. Further on, the catalyst recyclability was evaluated in a five-cycle test. The concentration of copper ions being dissolved in the treated water was monitored with ICP. After Cu₂O/H₂O₂ (membrane) treatment the effluent is qualified to discharge with COD concentration lower than 15 mg·L^-1 with regard to the national standard GB25467-2010.     

Degradation of an Anthraquinone Dye by Ozone/Fenton: Response Surface Approach and Degradation Pathway

A coupled O₃/Fenton process is applied to study the degradation ef?ciency of organic pollutants. The C.I. Acid Blue 80 (AB80), a kind of anthraquinone dye, is used as target contaminant. The results show that the combination of ozonation and Fenton process is a highly effective way of removing color from wastewater. Response surface methodology is applied to optimize the working conditions and the effects and interactions among initial pH (X₁), mole ratio of H₂O₂/Fe²⁺ (X₂) and ozone flux (X₃) are investigated. Regression equations determines that the best condition is that initial pH = 2.85, [H₂O₂]/[Fe²⁺] = 18.10 and ozone flux = 55.70 L.h^?1. It turns out the relative error of 1.32% with the predicted model when the actual value which is 88.76% in the best condition, compared to the predictive value of 88.95% under same condition. UV-Vis and FT-IR analysis are used as an assisted technique to study degradation mechanism during the oxidation process. The intermediate products are determined by gas chromatography/mass spectrometry (GC/MS) analysis and the plausible degradation pathway is proposed.     

超重力强化O3/H2O2氧化甲苯合成苯甲酸的研究

提出一种超重力环境下甲苯合成苯甲酸的新方法,对比不同臭氧化工艺合成苯甲酸的收率,研究了反应溶剂、臭氧气相浓度、过氧化氢与甲苯的摩尔比、超重力因子、液体流量对苯甲酸收率的影响规律。研究结果表明：RPB (rotating packed bed)-O₃/H₂O₂较其他工艺具有更高的反应性能;得到优化的工艺条件是反应溶剂为乙腈、臭氧气相浓度为80 mg·L^-1、过氧化氢与甲苯的摩尔比为0.15、超重力因子为40、液体流量为120 L·h^-1,在优化的工艺条件下得到苯甲酸收率为45%。通过电子顺磁共振仪 (EPR)对反应过程中产生的活性自由基进行表征,结果表明,O₃/H₂O₂体系中存在·OH。另外,用气相色谱-质谱联用仪(GC-MS)分析了中间产物,结果表明反应过程中生成的中间产物包括苯甲醇和苯甲醛。基于ERP实验和GC-MS表征结果,探索臭氧/双氧水氧化甲苯合成苯甲酸可能的反应历程。     

TNT的O3/H2O2降解规律

利用自制装置,采用连续投加O3、H2O2的方式,研究了O。／H：O：对废水中TNT的降解规律。结果表明,与Oa作用相比,O3／H2O2工艺可显著提高TNT的降解率,还可避免中间产物的形成与积累;在试验研究条件下,H2O2：O3的最优摩尔比为1,最佳初始pH值在11左右,利用缓冲溶液可维持反应体系pH值的稳定,但不利于O3／H2O2功效的发挥,反应适合在常温下进行,尽量避开40℃左右;动力学特征分析表明,O／H2O2降解TNT偏离伪一级反应动力学规律。     

丁基橡胶聚合新型超重力反应器工艺

将新型旋转填充床反应器（RPB）应用于阳离子聚合制备丁基橡胶（IIR）过程。实验初步考察了旋转填充床转子转速（N）和聚合温度（T_p）等工艺参数对聚合产物IIR分子量和分子量分布的影响规律。研究结果表明：在实验条件下,当N=1200 r·min^-1、T_p=-100℃时,采用超重力法新工艺制备的IIR的数均分子量达到2.89×10⁵,分子量分布指数达到1.99。同时,物料停留时间小于1 s (现工艺30~60min),单位设备体积的生产效率提高了2~3个数量级。随着N的增大和T_p的降低,聚合产物IIR的分子量升高,而分子量分布变化不大。     

超重力环境下O3/Fenton法处理含硝基苯废水

在旋转填充床(RPB)中超重力环境下采用O3/Fenton法处理含硝基苯废水,考察了Fenton试剂投加次数、超重力因子β、液体流量、初始pH值、Fe2+投加量、H2O2与Fe2+摩尔比对硝基苯去除率的影响. 结果表明,在硝基苯浓度175 mg/L、反应温度25℃、气体流量75 L/h、臭氧浓度40 mg/L、分3次投加Fenton试剂、溶液初始pH值4.5、超重力因子β=80、液体流量140 L/h和Fe2+总投加量1 mmol/L、摩尔比H2O2:Fe2+=5、循环处理40 min的条件下,硝基苯去除率和化学需氧量(COD)去除率分别为99.6%和87.6%. 相近条件下,与RPB-Fenton法相比,硝基苯去除率和COD去除率分别提高了36.3%和4.5%,与RPB-O3法相比分别提高了7.2%和47.1%,与BR(鼓泡反应器)-O3/Fenton法相比分别提高了11.3%和47.8%.     

Ozonation of o-phenylenediamine in the presence of hydrogen peroxide by high-gravity technology

The study herein investigated the effectiveness of simultaneous use of ozone and hydrogen peroxide(O_3/H_2O_2 process) to degrade o-phenylenediamine(o-PDA) in a simulated wastewater. A rotor–stator reactor(RSR) was employed to create a high-gravity environment in order to enhance ozone-liquid mass transfer rate and possibly improve the degradation rate of o-PDA. The degradation efficiency of o-PDA(η) as well as the overall gas-phase volumetric mass transfer coefficient(KGa) were determined under different operating conditions of H_2O_2 concentration, initial o-PDA concentration, temperature of reaction, initial p H and rotation speed of RSR in attempt to establish the optimal conditions. Chemical oxygen demand reduction rate(rCOD) of wastewater treated at a particular set of conditions was also analyzed. Additionally, the intermediate products of degradation were identified using a gas chromatography-mass spectrometer(GC/MS) to further evaluate the extent of o-PDA degradation as well as establish its possible degradation pathway. Results were validated by comparison with those of sole use of ozone(O_3 process), and it was noted that η, KGa and rCODachieved by O_3/H_2O_2 process was 24.4%,31.6% and 25.2% respectively higher than those of O_3 process, indicating that H_2O_2 can greatly enhance ozonation of o-PDA. This work further demonstrates that an RSR can significantly intensify ozone-liquid mass transfer rate and thus provides a feasible intensification means for the ozonation of o-PDA as well as other recalcitrant organics.     

微波／催化氧化法对废水中苯胺降解的研究

采用微波催化氧化法对苯胺模拟水的处理进行了初步的探讨分析;考察了微波时间、微波功率、pH值、H2O2浓度、高分子负载型催化荆质量对废水中苯胺降解的影响,确定了最佳工艺条件.在最佳工艺条件下,CODcr的去除率达到98%以上.     

The electrocatalytic oxidative polymerizations of aniline and aniline derivatives by graphene

Graphene oxide (GO) on a glassy carbon (GC) electrode was directly reduced at −1.0 V in a phosphate buffer (pH 4.15) to form graphene/GC electrode, which was used for the electrocatalytic oxidative polymerizations of aniline, o-aminophenol, and m-aminophenol in the acidic solutions using cyclic voltammetry, amperometric and potentiometric methods. Cyclic voltammograms demonstrate that the oxidation peak of aniline on the first cycle shifts from 1.13 V on the bare GC electrode to 0.76 V on the graphene/GC electrode. In addition, both amperometric and potentiometric methods also demonstrate that graphene can effectively catalyze the electrochemical oxidative polymerization of aniline. Cyclic voltammetry confirmed that graphene can pronouncedly catalyze the electrochemical oxidative polymerizations of o-aminophenol and m-aminophenol, but graphene oxide hardly catalyzes the electrochemical oxidative polymerizations of aniline and its derivatives. The ESR spectrum of graphene is quite different from that of graphene oxide.     

Degradation analysis of A2/O combined with AgNO3+K2FeO4 on coking wastewater

In this work, a coking wastewater was selected and a biochemical A~2/O treatment device for fractional degradation was designed and employed. After each stage of the treatment, the products were analyzed through gas chromatography–mass spectroscopy(GC–MS) to determine their composition. Finally, AgNO_3+ K_2 FeO_4 was used as an advanced deep catalytic oxidation treatment. It was concluded from the analysis that cyclic organics could be degraded and the chemical oxygen demand(COD) was controlled within 50 mg·L~(-1), in line with the target value. Meanwhile, the spectra obtained from the GC–MS were in accordance with the conclusions reached based on the COD. The research results showed that all hard-degradable organics in coking wastewater could be eliminated through the A~2/O bio-membrane treatment and the advanced treatment of making use of K_2FeO_4 as an oxidant and Ag+as a catalyst, the catalytic efficiency with Ag+as a catalyst of K+2FeO_4 was very high. Agcould evidently improve the oxidation capacity of K_2FeO_4 to wastewater in its short stability time, and this is an important innovation.     

Preparation of Fe3O4/MnOOH core-shell nanoparticles by a high-frequency impinging stream reactor☆

Well-defined Fe3O4/MnOOH nanoparticles with 61.1 emu·g?1 in magnetization intensity and 90.53 m2·g?1 in surface area have been synthesized by a new-style of high-frequency impinging stream (HFIS) reactor. In this reactor, two streams first collided together to form nano Fe3O4 suspension, which subsequently flew through an S-shaped maln channel to generate high-frequency reversing high-gravity fields. At the same time, 24 thin liquid sheets impinged into the maln channel at the frequencies higher than 100 Hz to create nano Fe3O4/MnOOH colloids. The obtalned powders were characterized by transmission electron microscopy/energy dispersive spectrometer (TEM/EDS), X-ray diffraction (XRD), Brunner–Emmet–Teller (BET) and vibrating sample magnetometer (VSM). Experimental results indicated that low coating ratio prolonged the induction period of heterogeneous nucleation. The high-frequency impingements of 24 thin liquid sheets greatly accelerated the macro-mixing and the initial dispersion. The high-frequency reversing high-gravity fields promoted the meso-and micro-mixing. As a result, nano Fe3O4 cores were fleetly and uniformly covered by MnOOH precursor. As a continuously operated and static high-gravity reactor, the high-frequency impinging stream (HFIS) reactor is being developed to the large-scaled and low-cost production of various nanocomposites.     

Degradation of salicylic acid by photo-assisted Fenton reaction using Fe ions on strongly acidic ion exchange resin as catalyst

The photo-assisted Fenton degradation of salicylic acid (SA) was studied by using strongly acidic ion exchange resin (SAIER) exchanged with Fe ions as catalyst in the presence of UV light (254 nm) and H₂O₂. The X-ray photoelectron spectroscopy (XPS) results revealed that the Fe ions are indeed anchored by the sulfonate groups on the surface of the SAIER and are Fe³⁺. Our results also indicate that the Fe/SAIER catalyst can significantly enhance the degradation rate of SA without remarkable Fe leaching to the solution, implying that the catalyst has photo-catalytic activity. In addition, the effects of [H₂O₂]/[SA] molar ratio, UVC light power, solution pH, catalyst loading, and initial SA concentration on the degradation of SA were investigated in detail.     

UV/O3工艺去除甲基叔丁基醚过程中BrO3-的产生与控制

引言臭氧用于饮用水处理已有悠久的历史,可有效去除色度和浊度,除异味,降解有机污染物和提高可生物降解性能。由于臭氧在紫外的激发下产生氧化能力更强的羟基自由基(·OH),该氧化剂与许多物质的反应速率常数在108～1010之间,因此,臭氧与紫外的联合作用能够迅速降解多种持久性有机物。面对水源地中出现的种类繁多的持久性有机物,UV/O3工艺受到了越来越多的关注。     

Degradation of PCDD/Fs in MSWI fly ash using a microwave-assisted hydrothermal process

In this work, microwave treatment was introduced to a hydrothermal treatment process to degrade PCDD/Fs (Polychlorinated dibenzo-p-dioxins and dibenzofurans) in municipal solid waste incineration (MSWI) fly ash. Three process additives (NaOH, Na₂HPO₄, H₂O), temperatures (150℃, 185℃, 220℃) and reaction times (1 h, 2 h, 3 h) were investigated to identify their effect on the disposal of fly ash samples through orthogonal experiments. High-resolution gas chromatography-mass spectrometry (HRGC/MS) was applied to determine the PCDD/F concentrations in MSWI fly ash. The experimental results revealed that 83.7% of total PCDD/Fs was degraded. Reaction temperature was the most important factor for the degradation of the total PCDD/Fs. Both direct destruction and chlorination reactions (the chlorination degree of PCDFs increased) took part in the degradation of PCDD/Fs in fly ash, which was a new discovery. Several PCDD/F indexes determined by the concentration of indicative congeners were found to quantitatively characterize the dioxin toxicity of the fly ash. Furthermore, heavy metals in the fly ash sample were solidified using microwave-assisted hydrothermal treatment, which provided an experimental basis for the simultaneous disposal of dioxins and heavy metals. Thus, the microwave-assisted hydrothermal process should be considered for the future disposal of MSWI fly ash.