Ozonation of 1,3,6‐naphthalenetrisulfonic acid in presence of heavy metals

A study was conducted of the mechanisms by which heavy metals, commonly present in industrial effluents, increase the purification effectiveness of ozone in the removal of organic contaminants of low biodegradability. For this purpose, the ozonation of 1,3,6‐naphthalenetrisulfonic acid (NTS) in the presence of Ni(II), Fe(II), Mn(II), Zn(II), Sr(II), Cr(III), Cd(II), Hg(II), and Cu(II) was examined. The presence of small amounts of Mn(II), Fe(II), Ni(II), Zn(II), and Cr(III) was observed in the system, increasing the degradation rate of the NTS and transforming the dissolved organic matter into CO₂. The mineralization of the organic matter was highly favored, especially in the first minutes of treatment. The results obtained appear to indicate that the activity of the metals in the NTS ozonation process is related to their reduction potential. Thus, metals susceptible to oxidation by ozone are potential promoters of NTS ozonation. The presence of Fe(II) or Mn(II) during NTS ozonation increased its degradation rate by 79% and 72% respectively. Moreover, the reaction kinetics of metal oxidation with ozone controls the increase in the purification effectiveness of these systems. The presence of radical scavengers (tert‐butanol or bicarbonate) in the medium during the promoted ozonation of NTS showed a negative effect on this process, and the NTS degradation rate decreased with an increasing concentration of these inhibitors in the system. These results confirm that the degradation of NTS by ozone in the presence of heavy metals occurs by a radical mechanism. O₃/Zn(II) and O₃/Fe(II) systems were applied to the decontamination of urban waste waters. The presence of Zn(II) or Fe(II) during the ozonation produced a reduction during the first 5 min of treatment of 20% or 44%, respectively, in the concentration of dissolved organic matter present in the system. These results show that ozonation in the presence of heavy metals is a highly promising system for the purification of waste waters and industrial effluents. Copyright © 2004 Society of Chemical Industry     

Photocatalytic ozonation of gallic acid in water

Aqueous solutions of gallic acid have been treated with five different oxidation‐radiation processes: visible and ultraviolet A radiation (VUVA), TiO₂ adsorption, ozonation, VUVA/TiO₂ photocatalysis and VUVA/O₃/TiO₂ photocatalytic ozonation. With the exception of VUVA radiation and TiO₂ adsorption, ozone and photolytic processes allow for the total removal of gallic acid in a period between 50 and 90 min. The time taken to achieve 100% gallic acid conversion depends on the oxidation process applied, photocatalytic ozonation being the most effective technique. Throughout the process, oxalic and formic acids were identified as byproducts. Some other unidentified compounds probably related to pyruvic, malonic and maleic acids were also detected. The appearance of these compounds can be justified from direct reactions of both hydroxyl radical and ozone in water. Only photocatalytic ozonation leads to total mineralisation of the organic matter in less than 90 min. The photocatalyst used, TiO₂, showed good activity and stability (no leaching was observed) after five consecutive photocatalytic ozonation runs with the same semiconductor‐catalyst mass. Copyright © 2006 Society of Chemical Industry     

Kinetics of esterification of lauric acid with fatty alcohols by lipase: effect of fatty alcohol

Lauric acid has been esterified with some C₁–C₁₈ aliphatic alcohols by a commercial lipase, Lipolase 100 L, using isooctane as a solvent. When lauric acid and fatty alcohols were taken in the mole ratio 1:1, first order kinetics were observed for all the alcohols studied. The highest reaction rate was observed for n‐butyl alcohol. Lauric acid was esterified with stearyl alcohol, in varying acid to alcohol mole ratios to explain the first order kinetics of the reaction. A kinetic model for the lipase‐catalysed esterification in a biphasic organic–aqueous system has been proposed. Based on the interfacial substrate concentration, an analytical rate equation for initial rate of the reaction was derived and confirmed with the experimental data. © 2002 Society of Chemical Industry     

Advanced oxidation processes for the degradation of p‐hydroxybenzoic acid 1: Photo‐assisted ozonation

The oxidation of p‐hydroxybenzoic acid in aqueous solution by UV radiation and by photo‐assisted ozonation (UV+O₃) has been studied. The effects of temperature (10, 20, 30 and 40 °C), pH (2, 5, 7 and 9) and ozone partial pressure (0.10–0.38 kPa) on the conversion of p‐hydroxybenzoic acid were established. Experimental results indicated that the kinetics for both oxidation processes fit pseudo‐first‐order kinetics well. In the combined process, the overall kinetic rate constant was split into two components: direct oxidation by UV radiation (photolysis) and oxidation by free radicals (mainly OH·) generated in the system. The importance of these two reaction paths for each specific value of ozone partial pressure, temperature and pH was quantified. Lastly, a general expression is proposed for the reaction rate which takes into account the two reaction pathways and is a function of known operating variables. © 2001 Society of Chemical Industry     

比值导数法对乙二醛和乙醛酸的二元混合物分析

用紫外光谱的比值导数法对乙二醛与乙醛酸的二元混合物进行分析,该方法能将乙二醛和乙醛酸重叠光谱分开并消除互相干扰,从而方便的完成两组分混合体系中各组分的测定。并对比值导数法的影响因素进行了分析说明。确定了最佳检测条件:肟化反应中乙二醛和乙醛酸的质量比>0.58,反应温度50℃,反应时间20 min,肟化剂用量1.0 mL。乙二醛、乙醛酸的检测下限分别为0.209,0.890 mg/L。乙二醛和乙醛酸的回收率分别达到96%~99.5%和97%~103%。     

Production of isophthalic acid from m-xylene oxidation under the catalysis of the H3PW12O40/carbon and cobalt catalytic system

Isophthalic acid (IPA) is commercially produced from m-xylene oxidation with the catalysis of the homogeneous Co–Mn–Br catalyst system. In this study, a catalytic system consisting of HPW/C and Co(II) has been put forward to oxidize m-xylene (MX) to IPA. The experimental results prove that the HPW/C and Co catalytic system is capable of catalyzing the oxidation of MX to IPA, which can obtain a higher MX conversion and IPA concentration than the homogeneous H₃PW₁₂O₄₀/Co(OAc)₂/Mn(OAc)₂ catalytic system. The heterogeneous catalytic system is also advantageous over the homogeneous catalytic system in the inhibition of the oxidation of acetic acid and IPA. The optimal amount of phosphotungstic acid supported on carbon is 7.5% (wt). The best dosage of HPW/C is 15 g l⁻¹. The optimum Co(II) concentration in the catalytic system for IPA production is 0.064% (wt). The best HPW/C activation temperature is 220 °C.     

Fully renewable limonene‐derived polycarbonate as a high‐performance alkyd resin

Limonene‐derived polycarbonate‐based alkyd resins (ARs) have been prepared by copolymerization of limonene dioxide with CO₂, catalysed by a β‐diiminate zinc–bis(trimethylsilyl)amido complex, and subsequent chemical modification with soybean oil fatty acids using triphenylethylphosphonium bromide as the catalyst. This quantitative partial modification was realized via epoxy–carboxylic acid chemistry, affording ARs with higher oil lengths, lower polydispersities and higher glass transition temperatures (T_g) in comparison to a conventional polyester AR based on phthalic acid, multifunctional polyol pentaerythritol and soybean fatty acid. The novel limonene polycarbonate AR and the conventional polyester AR were evaluated as coatings and both the physical drying (without the presence of the oxidative drying accelerator Borchi® Oxy Coat) and chemical curing (with Borchi® Oxy Coat) processes of these coatings were monitored by measuring the König hardness and complex modulus development with time. A better performance was obtained for the alkyd paint containing polycarbonates modified with fatty acids (FA‐PCs), which showed a faster chemical drying, a higher König hardness and a higher T_g in coating evaluation, demonstrating that the fully renewable FA‐PCs are promising resins for alkyd paint applications. © 2019 Society of Chemical Industry     

乙醛酸的合成及市场前景

对制备乙醛酸的各种方法作了详细的介绍,评述了各种生产方法的优缺点。提高其品质是开拓乙醛酸下游产品的关键,并指出改进目标是开发更为环境友好、无腐蚀的生产工艺。     

Ozone treatment of textile effluents and dyes: effect of applied ozone dose,pH and dye concentration

The ozonation of wastewater supplied from a treatment plant (Samples A and B) and dye‐bath effluent (Sample C) from a dyeing and finishing mill and acid dye solutions in a semi‐batch reactor has been examined to explore the impact of ozone dose, pH, and initial dye concentration. Results revealed that the apparent rate constants were raised with increases in applied ozone dose and pH, and decreases in initial dye concentration. While the color removal efficiencies of both wastewater Samples A and C for 15 min ozonation at high ozone dosage were 95 and 97%, respectively, these were 81 and 87%, respectively at low ozone dosage. The chemical oxygen demand (COD) and dissolved organic carbon (DOC) removal efficiencies at several ozone dose applications for a 15 min ozonation time were in the ranges of 15–46% and 10–20%, respectively for Sample A and 15–33% and 9–19% respectively for Sample C. Ozone consumption per unit color, COD and DOC removal at any time was found to be almost the same while the applied ozone dose was different. Ozonation could improve the BOD₅ (biological oxygen demand) COD ratio of Sample A by 1.6 times with 300 mg dm^?3 ozone consumption. Ozonation of acid dyes was a pseudo‐first order reaction with respect to dye. Increases in dye concentration increased specific ozone consumption. Specific ozone consumption for Acid Red 183 (AR‐183) dye solution with a concentration of 50 mg dm^?3 rose from 0.32 to 0.72 mg‐O₃ per mg dye decomposed as the dye concentration was increased to 500 mg dm^?3. © 2002 Society of Chemical Industry     

乙醛酸和草酸的高效液相色谱分析

采用高效液相色谱法测定了草酸电合成乙醛酸中乙醛酸和草酸的含量,方法简便,成本低廉,效果良好。色谱柱为VP-ODS(150 mm×4.6 mm),流动相为稀磷酸水溶液(pH=2.7),流速为0.5 mL/min,柱温40℃,检测波长为212 nm。探讨了pH值及其它条件对色谱分离的影响。乙醛酸的线性方程为:Y=1.226×102X-7.053×102,线性相关系数R=0.999 6,相对标准偏差为1.5%,检出限为3.0×10-9g;草酸的线性方程为:Y=1.670×103X-5.563×104,线性相关系数R=0.999 9,相对标准偏差为0.8%,检出限为2.3×10-10g。     

乙醛酸的应用及生产方法探析

本文简要介绍了乙醛酸在精细化工领域中的应用，并对乙醛酸的制备方法进行了分析.     

Selective Oxidation of Acetophenones Bearing Various Functional Groups to Benzoic Acid Derivatives with Molecular Oxygen

Acetophenones substituted by alkyl, alkoxy, acetoxy, and halogen groups were selectively oxidized with molecular oxygen to the corresponding benzoic acids by using the N,N′,N′′‐trihydroxyisocyanuric acid (THICA)/cobalt(II) acetate [Co(OAc)₂] and THICA/Co(OAc)₂/manganese(II) acetate [Mn(OAc)₂]. For example, 4‐methylacetophenone was selectively oxidized with molecular oxygen to 4‐acetylbenzoic acid (85%) by THICA/Co(OAc)₂ and to 4‐methylbenzoic acid (93%) by Mn(OAc)₂, while terephthalic acid was obtained in 93% with the THICA/Co(OAc)₂/Mn(OAc)₂ catalytic system. It is interesting that the acetyl group on the aromatic ring is efficiently converted by a very small amount of Mn(OAc)₂ to the corresponding carboxylic acid, and that the present method provides a versatile route to acetylbenzoic acids which are difficult to prepare by conventional methods.     

Wet oxidation of acetic acid by H2O2 catalyzed by transition metal-exchanged NaY zeolites

During the wet oxidation of contaminated wastewaters, the destruction of low molecular weight carboxylic acid intermediates such as acetic, glyoxalic, and oxalic acids is often the rate-controlling step. Oxidation of acetic acid, a very recalcitrant intermediate, requires compelling treatment severity. Heterogeneous catalytic wet oxidation of model acetic acid aqueous solutions was conducted under mild conditions (below the normal boiling point of water) using hydrogen peroxide over various transition metal-exchanged NaY zeolites. Treatment of Cu²⁺–NaY with oxalic acid [OA] led to a catalyst, Cu²⁺–NaY [OA], with significantly improved properties in terms of total organic carbon (TOC) removal efficiency and catalyst stability against leaching. This catalyst outperformed homogeneous Cu²⁺ by a factor of 2–2·5 times. Continuous feeding of H₂O₂ reduced its undesirable decomposition. Improvement of the TOC-degradation performance by Cu²⁺–NaY [OA] was tentatively attributed to the removal of sodium and possibly aluminium in the zeolite. © 1998 Society of Chemical Industry     

Mechanistic aspects of oxalic acid oxidation by photocatalysis and ozonation

Oxalic acid has been oxidised in acidic aqueous solutions (pH 3) using photocatalysis and ozonation alone or coupled. The simultaneous presence of ozone, titanium dioxide and near UV irradiation increases the oxidation rate of oxalic acid to values greater than those deriving from the single contributions of photocatalysis and ozonation. In particular in the present paper ozonation alone, heterogeneous photocatalysis and also combined ozonation with heterogeneous photocatalysis have been used for the oxidation of oxalic acid at acidic pH in the presence of TiO₂ Degussa P25. A likely mechanism, able to explain both the homogeneous and heterogeneous processes, is discussed.     

固定床电解槽变电流电解乙二醛合成乙醛酸

研究了支持电解质、阳极类型和变电流电解方式等因素对电解乙二醛合成乙醛酸过程的电流效率和乙醛酸选择性的影响。在选用的支持电解质中盐酸是最合适的支持电解质 ;固定床阳极电解效果优于平板型阳极电解效果 ;变电流电解效果好于恒电流电解效果。当阳极电解液初始组成为w(乙二醛 ) =7.0 %、w(盐酸 ) =8.0 % ,阴极电解液组成为w(硫酸 ) =2 0 %的水溶液 ,变电流电解的平均电流密度为 15 35A/m2 时 ,电流效率为 85 .0 %、乙醛酸选择性为 94.3% ,阳极初产品中m(乙醛酸 )∶m(乙二醛 )≥ 40∶3。     

Methodology Of Ozone Introduction Into Water And Wastewater Treatment

Theoretical basis and methodology for calculation and modeling of ozonation processes and contact equipment have been elaborated. Methodology of determination of reaction rate constant, stoichiometric coefficient, optimum values of pH, intermediate and final products, regimes of chemisorption, etc., for certain typical fast and slow reacting organic compounds (aniline, toluidine, humic acids, nitrobenzene, glyoxalic, oxalic and acetic acid) and wastewaters have been proposed. For calculation of the wastewater ozonation process, the value of chemical oxygen demand (COD) was suggested to be as a kinetic parameter from the solution side. On the basis of kinetic information, recommendations for the choice of the construction of contact equipment for the different chemisorption regimes of ozonation have been presented. Some new contact apparatuses have been proposed.     

乙醛酸合成方法及其应用

介绍了目前国内外乙醛酸的主要合成方法,并对其中某些方法进行了简单对比,简述了乙醛酸在香普、医药中间体、农药中间体等方面的应用。     

微波辐照二氯乙酸甲酯制备乙醛酸

利用微波辐照二氯乙酸甲酯制备乙醛酸,研究了微波功率、辐照时间对乙醛酸产率的影响,并与常规热反应进行了比较。研究结果表明,微波辐照所得乙醛酸的产率与常规加热法相近,但反应速率显著提高。当乙醛酸产率达到68%左右,常规热反应需要48h,利用400W微波辐照8h就可完成。在相同反应时间下,乙醛酸的产率随微波功率增大而增加。     

Decomposition of hydrogen peroxide in the presence of activated carbons with different characteristics

BACKGROUND: Catalytic ozonation promoted by activated carbon is a promising advanced oxidation process used in water treatment. Hydrogen peroxide generated as a by‐product from the reaction of ozone with some surface groups on the activated carbon or from the oxidation of some organic compounds present in the water being treated seems to play a key role in the catalytic ozonation process. Hydrogen peroxide decomposition promoted by two granular activated carbons (GAC) of different characteristics (Hydraffin P110 and Chemviron SSP‐4) has been studied in a batch reactor. The operating variables investigated were the stirring speed, temperature, pH and particle size. Also, the influence of metals on the GAC surface, that can catalyze hydrogen peroxide decomposition, was observed. RESULTS: Chemviron SSP‐4 showed a higher activity to decompose hydrogen peroxide than HydraffinP110 (70 and 50% of hydrogen peroxide removed after 2 h process, respectively). Regardless of the activated carbon used, hydrogen peroxide decomposition was clearly controlled by the mass transfer, although temperature and pH conditions exerted a remarkable influence on the process. Catalytic ozonation in the presence of activated carbon and hydrogen peroxide greatly improved the mineralization of oxalic acid (a very recalcitrant target compound). About 70% TOC (total organic carbon) depletion was observed after 1 h reaction in this combined system, much higher than the mineralization achieved by the single processes used. CONCLUSIONS: Of the two activated carbons studied, Chemviron SSP‐4 with an acidic nature presented a higher activity to decompose hydrogen peroxide. However the influence of the operating variables was quite similar in both cases. Experiments carried out in the presence of tert‐butanol confirmed the appearance of radical species. A kinetic study indicated that the process was controlled by the internal mass transfer and the chemical reaction on the surface of the activated carbon. The catalytic activity of hydrogen peroxide in oxalic acid ozonation promoted by activated carbon (O₃/AC/H₂O₂) was also studied. The results revealed the synergetic activity of the system O₃/AC/H₂O₂ to remove oxalic acid. Copyright © 2010 Society of Chemical Industry     

The pH Dependence and Effects of the Oxidative Products of Some Aromatic Compounds in Ozonation under Irradiation

Some aromatic compounds (o–nitrotoluene, p–nitrotoluene–2–sulfonic acid, and p–medthylaniline–3–sulfonic acid), were ozonized under UV irradiation separately, and the oxidative efficiencies of these reactions were studied. In order to ensure continued oxidation, it is advantageous to choose a proper pH value so as to fit the requirements of the chain reaction and also diminish the amound of HO. scavengers such as CO₃ ⁼ and HCO₃ ^? in oxidation Products. Removal of carbon dioxide could be effected by acidification of the reaction mixture. In order to decrease the inhibiting effect of the oxidation products, it is advisable to vary the pH value at different stages of UV ozonation. Many refractory organics usually encountered in industrial wastewater may resist degradative oxdation by ozonation alone, but can be destroyed rapidly by UV–radiation combined with ozonation.