干冰膨胀烟丝有机酸变化分析

把烟草中的有机酸衍生化后 ,用GC MS分别分析了烟丝干冰膨胀前后挥发性有机酸和非挥发性有机酸的含量。烟丝经干冰膨胀后 ,甲酸、乙酸、丙酸、2 甲基丙酸、丁酸、2 甲基 丁酸的含量有不同程度的升高 ,其中甲酸、乙酸的含量膨胀后明显增高 ;而戊酸、糠酸、庚酸、草酸、丙二酸、4 氧代戊酸、苹果酸、柠檬酸、肉豆蔻酸、棕榈酸、亚油酸、亚麻酸、十八碳酸的含量则有不同程度的下降。挥发性有机酸含量升高的幅度随挥发性的降低而降低 ,从戊酸开始有机酸的含量开始下降。     

序批式光合细菌产氢过程中底物的消耗特征

以葡萄糖和蛋白胨为底物,采用光合细菌PSB-ZF1进行了序批式产氢实验。通过对静态产氢底物的分析,研究了细菌的生长及产气过程中底物与产物的变化规律。结果表明,光合细菌对数生长期在接种12 h后出现,氢的产生与PSB-ZF1的生长是偶联的,最大产氢量为475 mL/L底物。底物中TOC、TN含量随时间呈逐渐下降趋势,产氢末期底物中TOC和TN浓度分别降至初始浓度的27.6%和33.8%。而IC浓度和pH值呈先下降后升高趋势,120 h时pH值达到最低值5.7。在底物中检测到甲酸、乙酸、丁酸和戊酸等4种低分子有机酸,未检测到丙酸。产氢初始阶段,底物中的甲酸、乙酸、丁酸浓度变化不大,光合细菌代谢产戊酸而不产丙酸,戊酸浓度在96 h达到最大值3.013 mmol/L。产气末期戊酸和丁酸被细菌代谢消耗掉,甲酸浓度上升至2.813 mmol/L,整个产气过程,乙酸的浓度维持在1.10¹.83 mmol/L之间。     

序批式光合细菌产氢过程中底物的消耗特征

以葡萄糖和蛋白胨为底物,采用光合细菌PSB-ZF1进行了序批式产氢实验。通过对静态产氢底物的分析,研究了细菌的生长及产气过程中底物与产物的变化规律。结果表明,光合细菌对数生长期在接种12 h后出现,氢的产生与PSB-ZF1的生长是偶联的,最大产氢量为475 mL/L底物。底物中TOC、TN含量随时间呈逐渐下降趋势,产氢末期底物中TOC和TN浓度分别降至初始浓度的27.6%和33.8%。而IC浓度和pH值呈先下降后升高趋势,120 h时pH值达到最低值5.7。在底物中检测到甲酸、乙酸、丁酸和戊酸等4种低分子有机酸,未检测到丙酸。产氢初始阶段,底物中的甲酸、乙酸、丁酸浓度变化不大,光合细菌代谢产戊酸而不产丙酸,戊酸浓度在96 h达到最大值3.013 mmol/L。产气末期戊酸和丁酸被细菌代谢消耗掉,甲酸浓度上升至2.813 mmol/L,整个产气过程,乙酸的浓度维持在1.10~1.83 mmol/L之间。     

反渗透膜法处理磷酸铁生产废水的零排放工艺研究

以硫酸亚铁为原料生产电池级磷酸铁过程中产生大量的含硫酸根、磷酸根、钠离子的废水。为减少废水排放并使之得到循环利用,采用反渗透膜技术对中试生产电池级磷酸铁的废水处理进行了零排放设计和实验研究,考察了进水压力、进水浓度、温度、pH等因素对硫酸根和磷酸根的截留率、膜通量和产水率的影响。实验结果表明所采用的反渗透膜对硫酸根、磷酸根的截留率达99.15%以上,进水压力、进水浓度、温度、pH等因素对截留率影响较小,但对膜通量和产水率影响较大。截留率随着进水压力的增加略有增加,随进水浓度增加和温度的升高而略有减小,膜通量和产水率随进水压力和温度的升高而增大,随进水浓度的增大而减小,pH=6.5时截留率、膜通量和产水率最高。同时采用生产废水制备了硫酸钙晶须,实现了废水零排放。     

低级脂肪酸与莰烯酯化反应的影响因素及C1～C5羧酸异龙脑酯的制备

讨论C1～C5低级脂肪酸与莰烯酯化反应制备脂肪羧酸异龙脑酯中催化剂硫酸的用量、反应时间、反应温度等几个因素对反应的影响,并介绍了甲酸异龙脑酯、乙酸异龙脑酯、丙酸异龙脑酯、丁酸异龙脑酯、异丁酸异龙脑酯、异戊酸异龙脑酯等一些低级脂肪酸酯的制备方法 。     

碱性条件促进纺织印染污泥厌氧发酵产挥发性脂肪酸

系统研究了酸性（pH值5、pH值6）、中性（pH值7）和碱性（pH值8～10）条件下,纺织印染污泥厌氧发酵产挥发性脂肪酸（VFA）的发酵类型,比较了总酸及主要酸的最高发酵浓度及分布、总酸及乙酸的产率和生产速率,并揭示了碱性条件有利于有机酸发酵的机制。研究结果表明,不同pH值条件下,乙酸型均为主要发酵类型,但较低的pH值利于丁酸累积。总酸及乙酸的浓度随着pH值的升高而增加,且碱性条件能够促进纺织印染污泥发酵产酸,原因为高pH值能促进有机物的降解并提高转化效率,同时较高的pH值抑制了有机酸的降解。pH值为10是厌氧发酵产酸并累积乙酸的最佳pH值。该条件下,乙酸和总酸的质量浓度达最高,为8.21 g/L和14.08 g/L;乙酸和总酸产率也达最高,为34.97%和75.72%;同时乙酸和总酸的生产速率达最高值,为2.41 g/(L·d)和3.48 g/(L·d)。pH值为6比较适合丁酸发酵,丁酸的最高浓度为1.89 g/L。     

预处理温度对剩余活性污泥生产挥发性脂肪酸的影响

考察了预处理温度对剩余污泥水解酸化生产挥发性脂肪酸(VFAs)的影响.分别在70、80、90、100℃下处理剩余活性污泥2 h,考察其水解酸化情况.结果表明:热处理可提高溶液中的SCOD及碳水化合物含量,提高效果随温度升高而增大;预处理温度对污泥产酸的促进效果为:90℃>80℃>100℃>70℃.经加90℃处理的活性污泥在缺氧条件下水解酸化30 h后,VFAs的产酸量达到最大,为946 mg/L.VFAs包括乙酸、丙酸、丁酸和戊酸,其中乙酸和丙酸为主要产物,热顶处理污泥可提高VFAs中乙酸的含量.     

低级脂肪酸与莰烯酯化反应的影响因素及C1～C5羧酸异龙脑酯的制备

本文讨论C1～C5低级脂肪酸与莰烯酯化反应制备脂肪羧酸异龙脑酯中催化剂硫酸的用量、反应时间、反应温度等几个因素对反应的影响,并叙述了甲酸异龙脑酯、乙酸异龙脑酯、丙酸异龙脑酯、丁酸异龙脑酯、异丁酸异龙脑酯、异戊酸异龙脑酯等一些低级脂肪酸酯的制备方法.     

气相色谱法测定环己烷氧化液中一元有机酸含量

应用GC-2010气相色谱仪和热导检测器、FFAP50 m ×0.32 mm ×0.4μm色谱柱,采用程序升温,外标法定量,建立了气相色谱法测定环己烷氧化液中一元有机酸含量的分析方法.结果表明:该方法准确测定了氧化液中甲酸、乙酸、丙酸、丁酸、戊酸、己酸含量.6种一元有机酸的标准曲线相关系数均大于0.98;该方法的相对标...     

氯化铁催化合成羧酸异戊酯

研究了氯化铁催化合成甲酸异戊酯、乙酸异戊酯、丙酸异戊酯、丁酸异戊酯、异丁酸异戊酯和异戊酸异戊酯。本法操作方便,反应温和,产品收率达８４％以上。     

Formation of short chain volatile organic acids in the automated AOM method

The end point in the automated AOM stability test for fats is related to the rapid production of volatile acids at the end of the induction period and usually measured by conductivity of an aqueous solution of the exit gases. It has been postulated that the reaction involves the transitory presence of a diperoxide which decomposes into two aldehydes and formic acid. The volatile acids produced by several oils were composed mainly of formic acid and significant amounts of acetic acid. In addition, acids with three or more carbon atoms, including propionic, butyric and caproic, were detected. It was found that the temperature of the water in the receiving jars was important in relation to retention of the formic acid. At temperatures above 20 C significant losses may occur. The relationships between peroxide value of the oils, the conductivity of the exit gas solutions and the organic acid content was investigated for the following fats and oils: sunflower, canola, olive, corn, peanut and soybean oil, triolein, lard and butterfat.     

不同循环比条件下水解酸化工艺处理厌氧发酵液

采用水解酸化工艺处理厌氧发酵液,研究了不同循环比条件下,水解过程挥发性脂肪酸和氮元素转化规律。结果表明：水解过程产生的挥发性脂肪酸主要有甲酸、乙酸和丙酸,仅有少量样品检测出甲酸,乙酸和丙酸占有机酸总量比例较大。在循环比为1/3条件下产生的有机酸的种类、总量比其它两个条件要多。处理后出水中COD浓度与有机酸总量、乙酸、丙酸浓度均呈线性关系。循环比1/3条件下,处理后出水中氨氮和硝态氮浓度最低（分别为3.57 mg/L和48.60 mg/L）,脱氮效果最好。     

Short-chain fatty acids as growth inhibitors in decomposing wheat straw

The aqueous extract of decomposing wheat straw in water was inhibitory to the seedling growth of wheat (Triticum aestivum L.). The major compounds isolated from the toxic fractions were salts of acetic, propionic, and butyric acids. Amounts of these acids increased gradually up to 12 days and the toxicity of the straw extract increased accordingly. Traces of isobutyric, pentanoic, and isopentanoic acids were also identified by gas chromatography-mass spectrometry.Journal Series No. 2167 of the Hawaii Agricultural Experiment Station.     

Separation of some light monocarboxylic acids from water inbinary solutions in a reverse osmosis pilot plant

The separation of formic (C₁), acetic (C₂), propionic (C₃), and n-valeric (C₅) acids in binary water solutions has been studied using a reverse osmosis (RO) membrane pilot plant operating at different temperatures and pressures (usually 21 °C and 1.72 MPa). The RO membrane, which is composite, polyamide and spiral-wound, having a surface area of 2.6 m², was fed by a solution of 0.5 M of C₁, C₂ and C₃ acids and 0.146 M of C₅. The pilot plant was used to simulate a cascade series of RO modules by recycling the permeate flux at the end of each semi-batch run. The influence on the retention coefficient, R, of molecular weight and molar volume, pK_a of the different acids was determined. For acetic acid the influence of temperature (T) and transmembrane pressure (ΔP) was also studied, obtaining an inverse and direct good linear correlation for R vs. T and R vs. ΔP, respectively. The results are particularly interesting for acetic acid-water separation, which is an open question in industrial applications.     

Uptake of organic acids byClostridium acetobutylicum B18 under controlled pH and reduced butanol inhibition

Uptake of organic acids byClostridium acetobutylicum B18 was studied at controlled pH and under reduced butanol inhibition conditions. A pervaporative membrane module was placed in the fermentor to remove butanol from the fermentation broth. Uptake of added butyric acid followed zero order kinetics at pH 4.75 and first order kinetics at pH 5.75. At pH 5.25 the kinetic order shifted from zero to first order as the butyric acid was taken up. At the point of order shift undissociated butyric acid (UBA) concentration was approximately 0.5 g/L. Unlike butyric acid, uptake of acetic acid followed first order kinetics regardless of pH. The difference in acid uptake kinetics could be explained by the combined effect of acid diffusion across the cell membrane and intracellular enzymatic reaction. The acid concentration for kinetic order shift seemed to be dependent upon pH and the kind of the acid used. Glucose was consumed simultaneously with added acids. Both butyric and acetic acids were taken up simultaneously but the rate was faster for butyric acid. Added butyric acid was completely assimilated whereas acetic acid uptake was incomplete.     

Effects of organic acids on the performance of cellulose triacetate forward osmosis membrane

Forward osmosis (FO) membrane performance was improved using different organic acids (formic acid, acetic acid, lactic acid) for the addition of the casting solution. Scanning electron microscope (SEM) images of all the FO CTA membranes exhibited essentially the membranes have a structure of looking like two dense skin layers and a sponge‐like supporting layer. Additionally, based on the surface roughness values analysis of Atomic Force Microscope (AFM), the membranes with lactic acid, with similar roughness to the membranes without any acid, have bigger roughness than the membranes with formic acid or acetic acid. Furthermore, the water flux of membranes with acids has been improved and the reverse salt flux decreased. The membranes with lactic acid, with an outstanding penetration performance, were utilized to test the performance when 1 mol/L sodium chloride (NaCl), magnesium chloride (MgCl₂)_, magnesium sulfate (MgSO₄), and sodium sulfate (Na₂SO₄) were, respectively, as the draw solutions. The results revealed that the membranes have a higher rejection ratio for MgSO₄. Besides, in the process of separating oil–water mixture, the membranes with the organic acids have a better separation efficiency than the membrane without any acid during FO process and the water flux recovery rate could achieve above 90% insuring the membrane anti‐fouling. POLYM. ENG. SCI., 59:E138–E145, 2019. © 2018 Society of Plastics Engineers     

真空膜蒸馏浓缩反渗透浓盐水的工艺研究

分别采用聚乙烯、聚丙烯微孔膜对反渗透海水淡化浓盐水进行真空膜蒸馏的研究。考察了膜下游真空度、浓盐水温度、浓度、流速对膜通量及截留率的影响。结果表明,真空度增大,膜通量和截留率呈增长趋势。料液温度升高,膜通量增加,截留率呈减少趋势。料液流速增加会使通量增加,截留率呈减少趋势,但影响相对不大。随着料液浓度的增加,膜的通量下降,截留率基本保持不变。本实验条件下最大截留率可达99．99％,表明利用真空膜蒸馏技术可有效实现反渗透海水淡化浓盐水的浓缩。