Formation of toxic aldehydes in cod liver oil after ultraviolet irradiation

Formaldehyde, acrolein, malonaldehyde (MA), acetaldehyde and propanal produced from cod liver oil upon ultraviolet irradiation (λ_max=300 nm) were derivatized into nitrogenor sulfur-containing compounds and then analyzed by capillary gas chromatography with a nitrogen-phosphorus detector or a flame photometric detector. Acrolein and MA were formed at levels of 10.9±3.06 and 190.2±38.4 nmol/mg of fish oil, respectively. Maximum levels of formaldehyde, acetaldehyde and propanal formed were 7.0±0.90, 49.1±4.5 and 35.8±4.0 nmol/mg of oil, respectively. Formation of propanal in large quantities corresponded to the high content of ɛ-3 fatty acids in cod liver oil.     

肟交换法制备乙醛肟工艺的研究

肟交换法是一种制备乙醛肟的新兴工艺,但反应过程存在乙醛肟易被空气氧化等问题,且反应液中存在多组共沸物,分离提纯得到高纯度的乙醛肟较为困难。以丁酮肟为原料,通过向反应器内充入0.2 MPa的氮气,有效避免了乙醛肟氧化与原料乙醛、丁酮肟的挥发,乙醛肟反应选择性达96.12%。开发了产物的提纯工艺,通过Aspen Plus模拟,初步确定减压精馏分离反应液的基本流程,考察了压力、塔板数、回流比、进料位置等操作参数对分离过程的影响。在此基础上,依据模拟确定的操作参数进行实验,确定最优分离提纯工艺,得到纯度为95.33%的乙醛肟产品,收率可达94.31%。本研究可为肟交换法制备乙醛肟的工业化提供一定的指导。     

柿果实的脱涩机理

概述了近20年来柿果实脱涩机理的研究进展,评述了甜柿果实的自然脱涩过程,讨论了乙醇和乙醛处理对涩柿果实的脱涩作用,指出了乙醇是直接与可溶性柿单宁起缩合反应而使柿果实脱涩的化学物质。     

Photocatalytic degradation of methylene blue and acetaldehyde by TiO<Subscript>2</Subscript>/glaze coated porous red clay tile

Nanosized TiO₂ sol synthesized by sol-gel method was successfully coated on the porous red clay tile (PRC tile) with micrometer sized pores. PRC tile was first coated with a low-firing glaze (glaze-coated PRC tile) and then TiO₂ sol was coated on the glaze layer. A low-fired glaze was prepared at various blending ratios with frit and feldspar, and a blending ratio glazed at 700 °C was selected as an optimum condition. Then TiO₂ sol synthesized from TTIP was dip-coated on the glazed layer (TiO₂/glaze-coated PRC tile), and it was calcined again at 500 °C. Here, these optimum calcination temperatures were selected to derive a strong bonding by a partial sintering between TiO₂ sol particles and glaze layer. Photocatalytic activity on the TiO₂/glaze-coated PRC tile was evaluated by the extent of photocatalytic degradation of methylene blue and acetaldehyde. Methylene blue with the high concentration of 150 mg/l on the surface of TiO₂/glaze-coated PRC tile was almost photodegraded within 5 hours under the condition of average UV intensity of 0.275 mW/cm₂, while no photodegradation reaction of methylene blue occurred on the glaze-coated PRC tile without TiO₂. Another photocatalytic activity was also evaluated by measuring the extent of photocatalytic degradation of gaseous acetaldehyde. The photodegradation efficiency in TiO₂/glaze-coated PRC tile showed about 77% photocatalytic degradation of acetaldehyde from 45,480 mg/l to 10,536 mg/l after the UV irradiation of 14 hours, but only about 16% in the case of the glaze-coated PRC tile.     

Understanding the electrocatalytic activity of PtxSny in direct ethanol fuel cells

In the present work, the activity of Pt_xSn_y/C catalysts towards ethanol, acetaldehyde and acetic acid electrooxidation reactions is investigated for each one separately by means of cyclic voltammetry. To this purpose, a series of Pt_xSn_y/C catalysts with different atomic ratio (x:y = 2:1, 3:2, 1:1) and small particle size (∼3 nm) are fast synthesized by using the pulse microwave assisted polyol method. The catalysts are well dispersed over the carbon support based on the physicochemical characterization by means of XRD and TEM. Concerning the ethanol electrooxidation, it is found that the Sn addition strongly enhances Pt's electrocatalytic activity and the contributing effect of Sn depends on: (i) the Sn content and (ii) the operating temperature. More precisely, at lower temperatures, Sn-rich catalysts exhibit better ethanol electrooxidation performance while at higher temperatures Sn-poor catalysts give better performance. In the case of acetaldehyde electrooxidation, Pt₁Sn₁/C catalyst exhibits the highest activity at all the investigated temperatures; due to the role of Sn, which could effectively remove C₂ species and inhibit the poison formation by supplying oxygen-containing species. Finally, it is found that the Pt_xSn_y/C catalysts are almost inactive (little current was measured) towards the acetic acid electrooxidation. The above findings indicate that Sn cannot substantially promote the electrooxidation of acetic acid to C₁ species.     

Influence of fermentation oxygen partial pressure on semicontinuous acetification for wine vinegar production

This paper describes semicontinuous acetic acid fermentations for wine vinegar production carried out with different aerating gas compositions ranging from 21% (air) to 63% oxygen content and using low aeration (3.7 h^–1, vvm), in order to study the influence of the oxygen partial pressure on the aerating gas supplied to the reactor in this industrial biotransformation process. The acetification process was conducted in 6- to 100-l reactors. The overall acetic acid productivity increased from 0.72 g l^–1 h^–1 with air to 1.35 g l^–1 h^–1 when oxygen-rich (36%) air was used. The same behaviour was observed for the maximum acetification rate, and therefore the total process time was reduced in proportion to the increase in productivity, from 65 h using air to 35 h using an aerating gas mixture containing 36% oxygen. The yield of the process was high, 96–99%; the final concentration of acetic acid reached was 116–118 g l^–1; and the substrate yield coefficient based on ethanol metabolised was higher using oxygen-rich air than with air. It was not feasible to carry out semicontinuous acetification cycles with an oxygen content higher than 40%, and when the oxygen content was 63%, the process stopped during the first cycle with very little acetic acid production. Moreover, an inverse relationship between the acetic acid formation rate profile in the course of the acetification process and the amount of dissolved acetaldehyde in the fermentation broth formed by the acetic bacteria was observed.     

乙醛装置废水循环利用

对乙醛装置洗涤塔单元和废水系统进行技术改造，装置部分废水循环利用，代替脱盐水作为洗涤塔的洗涤水，节能降耗，降低成本。     

热成像技术在乙醛生产设备热故障识别中的应用

通过红外热像的测试，结合设备结构特点．对已醛装置中的再生器、反应器、除沫器村里的脱落、裂纹及减薄等故障的热特性进行了分析与识别，获得的热像特性可供同类设备参考。     

Commercially important characteristics of Turkish origin domestic strains of Streptococcus thermophilus and Lactobacillus delbrueckii ssp. bulgaricus

Thirty native (Turkish origin) strains of Streptococcus thermophilus and 24 strains of Lactobacillus delbrueckii ssp. bulgaricus were isolated and identified. These strains were examined for their technologically important properties such as acidification, proteolysis, acetaldehyde production and antimicrobial activity. By taking into consideration their phage resistant properties, two strains of S. thermophilus (St.7.7, and St.26.2) and one of L. bulgaricus, numbered as 2004, were found to have the potential to be starters for yogurt production.     

Ozonation of Several Organic Compounds Having Low Molecular Weight under Ultraviolet Irradiation

Ozonation of several low molecular weight organic compounds under ultraviolet irradiation was studied. Nine compounds were identified as reaction products of the ozonation of phenol which was promoted by the simultaneous use of ozone and ultraviolet irradiation. In the case of several organic compounds having carbon numbers from one to six, the removal of total organic carbon (TOC) by this simultaneous use was higher than by either the ozone oxidation method or the ultraviolet irradiation method for all the compounds.