乙酰丙酮分光光度法测定微量甲醛

探讨在高含量氨干扰下,用乙酰丙酮分光光度法测定水样中微量甲醛的可行性。通过试验,确定含氨量较高的水溶液中微量甲醛的分析方法。     

乙酰丙酮分光光度法测定啤酒中甲醛

建立了检测啤酒中甲醛含量的新方法。在酸性条件下将溶解于水中的游离甲醛随水蒸出,馏出液中甲醛与乙酰丙酮作用,在100℃水浴中加热生成稳定的二乙酰基二氢吡啶化合物,冷却后在415nm处测吸光度,即可测的啤酒中甲醛含量。方法检出限为0.12μg/10mL,线性范围:0.0-8.0μg/10mL,RSD为0.73%-2.39%。样品加标回收率在98.4%-102.6%。该方法简便,灵敏度高,重线性好,适合啤酒中甲醛的测定。     

乙酰丙酮比色法测定甲醛的标准化探讨

乙酰丙酮比色法测定材料中游离甲醛为多种标准所采用,但各标准规定的测定条件各不相同.本文通过用标准规定的方法对甲醛标准液以吸光度为横坐标,以最终显色体系中游离甲醛的浓度为纵坐标绘制标准曲线.各标准曲线的斜率用t检验分析,证明无显著性差异.可采用某个标准中测定甲醛的方法对多种材料的甲醛吸收液进行定量检验.     

乙酰丙酮分光光度法测定水性涂料及胶粘剂中的甲醛含量

本文介绍了既可测定水性涂料中的甲醛、又可测定胶粘剂中甲醛的乙酰丙酮分光光度法,水性涂料、胶粘剂样品中甲醛测定结果的相对标准偏差分别为1.4%、0.8%,甲醛的回收率分别为93.1%～96.2%和92.2%～95.1%,采用改进后的乙酰丙酮分光光度法测定水性涂料及胶粘剂中的甲醛含量,精密度和准确度较高,可满足GB18582-2001及GB18583-2001中对甲醛含量的控制要求.     

乙酰丙酮分光光度法测定纤维板甲醛释放量的不确定度评定

文章依据GB／T17657—1999对用于测定纤维板中有害物质甲醛的乙酰丙酮分光光度法的不确定度进行了研究。建立了数学模型,详细分析了测定过程中影响结果的各个分量,并对各不确定度分量进行评定,计算出了该法的合成不确定度和扩展不确定度。     

用乙酰丙酮分光光度法测定皮革、毛皮产品中的游离甲醛

采用丹麦FOSS水蒸汽蒸馏装置,收集样品中的游离甲醛,再用乙酰丙酮分光光度计法进行测定。该方法简捷快速,灵敏度高,重现性好,避免了样品萃取液不经蒸馏带有颜色及萃取液浑浊带来的系统误差,适用于皮革、毛皮产品中游离甲醛的测定。     

荧光分光光度法测定洗涤剂中痕量甲醛

建立了荧光分光光度法检测洗涤剂中痕量甲醛的方法体系,在最佳实验条件下,甲醛质量浓度在0.01～1.0μg/mL范围内呈良好的线形关系,相关系数r=0.9990。与其它甲醛测定法相比,该法操作简便,检测准确,重现性好。应用于实际洗涤剂样品中甲醛含量的痕量测定,结果较为满意。     

同步荧光法测定废水中微量十二烷基苯磺酸钠

以丁基罗丹明B为荧光探针,用同步荧光分析法测定工业及生活废水中微量十二烷基苯磺酸钠。实验结果表明:在pH 6.0的缓冲溶液中,十二烷基苯磺酸钠对丁基罗丹明B的荧光具有较强的猝灭作用,十二烷基苯磺酸钠为0~128.0μg/mL时,荧光猝灭程度与其质量浓度呈直线关系,检出限为0.085 6μg/mL。     

荧光分光光度法测定人造板中游离甲醛的含量

建立了乙酰丙酮荧光分光光度法测定人造板中游离甲醛的方法,选择了最佳实验条件。结果表明,甲醛质量浓度在0.04～1.0μg/mL范围内符合线性关系,最低检出限为5.7×10-3μg/mL。与其它光度法相比,操作简便,重现性好,灵敏度高,检测速度快,可应用于实际样品中游离甲醛释放量的测定。     

以3，5－二溴水杨醛缩氨基硫脲为荧光萃取剂测定水中阳离子表面活性剂

以３，６－二溴水杨醛缩氨基硫脲（３，５－ＤＢＳＴＳ）为试剂，提出了萃取荧光法，用于废水中微量阳离子表面活性剂的测定，探讨了反应机理。ＣＴＭＡＢ的检出限为１．８×１０￣（－８）ｍｏｌ／Ｌ，λ＿（ｅｘ）／λ＿（ｏｍ）＝４００ｎｍ／４６０ｎｍ。     

多相催化氧化伯醇制备羧基化合物研究进展

伯醇催化氧化制羧基化合物是有机合成中一类极为重要的转化过程,具有广泛的应用场景。对于多相催化系统,高效催化剂的制备一直是研究的热点和难点。本文对近年来涉及多相催化氧化伯醇制备羧基化合物的文献进行了全面的梳理。从单金属和双金属活性组分,以及是否采用载体等角度,系统评估了伯醇氧化多相催化剂的发展现状和趋势,并展望了多相催化在工业应用中的发展前景和挑战。     

用新型氧化剂DMF—NO2合成偶氮脲

在丙酮溶剂中,利用新型氧化剂ＤＭＦ－ＮＯ２将８种取代氨基脲高产率地氧化为新型偶氮化合物,反应条件温和。现象明显,产物容易分离。     

Simultaneous oxidation of aromatic compounds using Sr-doped lanthanum manganites as catalysts

Strontium-doped lanthanum manganites, La_1-xSr_xMnO₃ (LSMO), are promising and affordable catalysts for oxidative degradation of volatile organic compounds. LSMO catalysts (x = 0, .1, .2, and .3) were prepared by the citrate-nitrate autocombustion (CNA) and coprecipitation synthesis. The phase composition was confirmed by X-ray diffraction and Rietveld refinement analysis, while the oxygen content was determined by Mohr's salt permanganate titration. Morphology and porosity of prepared catalysts was correlated to catalytic oxidation of benzene, toluene, ethylbenzene and o-xylene. It was observed that both synthesis methods yielded catalysts of similar average pore size diameter and specific surface area, but the pore size distribution differed: CNA-prepared catalysts had a multimodal pore size distribution, while the coprecipitated ones had a single maximum at 4 nm. Catalysts prepared by the CNA method have shown a higher catalytic activity in the temperature range 373–723 K, as the presence of Mn³⁺/Mn⁴⁺ mixed valences increased their reducibility.     

Thiocyanation of aromatic and heteroaromatic compounds using polymer-supported thiocyanate ion as the versatile reagent and ceric ammonium nitrate as the versatile single-electron oxidant

Indoles, pyrrole aniline derivatives and aromatic amino compounds undergo smooth thiocyanation with cross-linked poly (4-vinylpyridine) supported thiocyanate ion, [P₄-VP]SCN in the presence of ceric ammonium nitrate (CAN) as a versatile single-electron oxidant in ethanol at room temperature to afford the corresponding 3-indolyl 2-pyroyl and 4-aryl thiocyanates, respectively, in high to excellent yields with excellent selectivity in a short reaction time. The use of [P₄-VP]SCN/CAN makes it quite simple, more convenient, and practical. The present procedure offers advantages such as short reaction time, simple reaction work-up, and the polymeric reagents can be regenerated and reused for several times without significant loss of their activity.     

Synthesis of biodegradable glycolide/l-lactide copolymers using iron compounds as initiators

The aim of this paper is to present a new method of copolymerization of glycolide with l-lactide with the use of low toxic iron compounds. The use of Fe(acac)₃ and Fe(OEt)₃ initiators enabled one to obtain copolymers with yields up to 100% and possessing good mechanical properties. The chain propagation process and the influence of the transesterification was examined.On the basis of NMR examination and DSC thermograms, it was shown that the samples obtained at the temperature of 100 °C with the use of the initiators have quasi-segmental chain microstructure.     

HRP biosensor based on sugar-lectin biospecific interactions for the determination of phenolic compounds

A layer-by-layer self-assembly of concanavalin A (Con A) and glycoprotein horseradish peroxidase (HRP) afforded multilayer thin films on the surface of a thiol-modifed gold electrode, through biospecific complexation of Con A and sugar residues in the glycoenzymes. The performance of the HRP biosensor is reported for the amperometric detection of phenolic compounds. The concentration of hydrogen peroxide and assembly conditions of the precursor film, such as pH, the ionic strength of the polyelectrolyte solutions and the number of assembled bilayers were investigated using catechol. With optimized conditions, the biosensor presented a linear response for catechol from 6.0 to 48.0 μmol l⁻¹, with a high sensitivity of 160 μmol⁻¹ l nA and a detection limit of 0.6 μmol l⁻¹. The response time of the biosensor for phenolic compounds was very short, reaching 95% of its maximum response in about 2 s. The differences in sensitivity observed for a series of phenolic substrates were discussed in terms of the stability of the oxidized phenolic compounds and the properties of substituents.     

GC-MS解析炼化污水中挥发性有机物组成和变化

对西北某大型炼化企业炼油、化工两条污水处理流程的关键工艺环节进行水样采集,采用紫外可见光谱及吹扫捕集-气相色谱与质谱联用（GC-MS））解析了污水水样中挥发性有机成分的组成和含量的变化。共鉴定出有机物19类76种,化工污水当中的有机物（43种）相对炼油污水（32种）更加复杂。研究表明,炼油污水含较多的含硫化合物（硫醚、噻吩）,是恶臭气体的主要来源;化工污水含较多的含氮化合物（硝基化合物、腈类、氰类）,是氨氮及总氮的主要贡献者;芳香化合物种类多达数十种,对VOCs贡献较大。指出化工污水水解环节可产生部分醇、酮类化合物,提高后续污水可生化性。生化处理环节能去除污水中的绝大部分烷烃、烯烃、炔烃和少部分醇、酮;而芳香烃、多环芳烃、氯代烃生物降解性相对较差,生化后依旧具有残留,是污水处理COD残留的重要原因,可作为炼化特征有机污染物。提出分子水平的精细解析,能够为污水处理工艺评价提供科学依据,进而对工艺开发和工艺改进提供帮助。     

Removal of anilinic compounds using the NF-97 membrane: Application of the solution-diffusion and SKK models

In the present work, the characterization of the polyamide membrane NF-97 has been carried out studying its behaviour in the treatment of effluents that contain anilinic compounds. High rejection coefficients with a maximum value of 94.72% for aniline, 79.83% for 4-chloroaniline, and 63.63% for 4-nitroaniline were obtained with operating pressures of about 30 bar and pH values between 3 and 4. The fouling parameter based on solute permeate flux was higher than that for the solvent permeate flux and higher for magnesium chloride. Lastly, experimental data were fitted to the Solution-Diffusion model and to the simplified model of Spiegler–Kedem–Katchalsky.     

Selective oxidation of aromatic compounds on zeolites using N2O as a mild oxidant: A new approach to design active sites

Dehydroxylated ZSM-5 type zeolites are used for selective oxidation of aromatic compounds, including benzene, chlorobenzene, styrene, difluorobenzenes, phenol, alkylbenzenes into corresponding phenols and diphenols using nitrous oxide as a mild oxidant. In the case of benzene, the yield of phenol reaches 70–80%. Extremely high selectivity (98–100%) in the case of benzene and 85% in the case of difluorobenzenes and high regioselectivities are observed on the dehydroxylated HZSM-5 zeolite. The active sites are shown to be the strong Lewis acid–base pair sites formed upon dehydroxylation of the zeolites. The reaction mechanism that is alternative to the proposed iron-mediated mechanism is discussed.