反渗透膜处理含有机酸凝结水技术

采用反渗透膜对某制药厂含甲酸、乙酸、丙酸、丁酸、戊酸、己酸、异丁酸和2-甲基丁酸的凝结水进行处理,研究了进水温度、压力和pH值对凝结水中有机酸截留效果的影响,讨论了反渗透膜对有机酸的截留机理。研究结果表明：温度为20～40 ℃、压力为0.5～1.5 MPa、pH值为4～10时,产水中丁酸、戊酸、己酸和2-甲基丁酸的浓度低于检测限,甲酸、乙酸、丙酸和异丁酸的截留率随着压力和pH值增加而增大,随着温度升高而降低;产水率随着压力增大、温度升高而增大,不受pH值变化影响。说明反渗透膜对有机酸的机械筛除作用及膜与有机酸之间的电荷作用对有机酸的截留具有重要影响。     

Studies on transport properties of short chain aliphatic carboxylicacids in electrodialytic separation

An electrodialysis process was employed to investigate the concentration of formic, acetic and propionic acid solutions under different experimental conditions. In this process interpolymer-type ion-exchange membranes were used due their high chemical stability and durability. The effects of concentration, electric current and time on the electrodialysis process were studied. A mathematical equation representing the water transport behavior of the electrodialysis process for concentrating acids under the influence of different current densities was developed. This equation is valid for any electrodialysis process with ion-exchange membranes used under similar operating conditions. The reliability of the water transport equation was tested through comparison with the experimental data. Results indicate that electrodialysis is an effective method for concentrating shorter chain aliphatic carboxylic acid solutions. Ionic transportation, power consumption and current efficiency data reveal the following trend of the electrodialysis process's efficiency during concentration of carboxylic acid solutions: formic acid > acetic acid > propionic acid.     

5-烷基-2-氨基-1,3,4-噻二唑的合成及应用

用硫代氨基脲与甲酸、乙酸、丙酸、丁酸、异丁酸、异戊酸等在盐酸、磷酸、多聚磷酸、硫酸催化下 ,分别合成了 2 -氨基 -1 ,3 ,4-噻二唑 (a)、5 -甲基 -2 -氨基 -1 ,3 ,4-噻二唑 (b)、5 -乙基 -2 -氨基 -1 ,3 ,4-噻二唑 (c)、5 -丙基 -2 -氨基 -1 ,3 ,4-噻二唑 (d)、5 -异丙基 -2 -氨基 -1 ,3 ,4-噻二唑 (e)、5 -异丁基 -2 -氨基 -1 ,3 ,4-噻二唑 (f)。并对工艺条件进行了试验 ,结果表明 :最佳工艺条件为硫代氨基脲与酸的摩尔比为 1∶ 1 .4,合成 2 -氨基 -1 ,3 ,4-噻二唑为多聚磷酸催化 ,合成其它的为浓盐酸催化 ,回流 3 h,产率分别为 96.78%、74.3 4%、73 .67%、71 .68%、68.44%、67.5 4%。同时以 a～f为原料合成了具有抗菌作用的 5 -烷基 -1 ,3 ,4-噻二唑硫脲乙酸和 5 -烷基 -2 -苯基 -硫脲 -1 ,3 ,4-噻二唑的衍生物     

Liquid+liquid equilibria of ternary water+carboxylic acid+solvent systems at 288.15 K

The experimental liquid-liquid equilibrium (LLE) data for six ternary systems containing (chloroform+propionic acid+water), (chloroform+acetic acid+water), (diethyl ether+propionic acid+water), (diethyl ether+acetic acid+water), (trichloroethylene+propionic acid+water) and (trichloroethylene+acetic acid+water) were measured at 288.15 K and at atmospheric pressure. An accurate and simple titration method was used for determining of the concentration of carboxylic acid in the both liquid phases at equilibrium. The reliability of the experimental tie-line data was confirmed by using the Othmer-Tobias correlation. The distribution coefficients and selectivity factors were presented to evaluate the efficiency of the solvents for extraction of carboxylic acid from water. The results show that chloroform and diethyl ether are satisfactory solvents for extraction of carboxylic acids from water. Trichloroethylene separates propionic acid from water; however, it cannot be used as a solvent for separation of acetic acid.     

缔合体系汽-液平衡的研究(Ⅰ)——二元缔合体系

本文给出了含缔合组分二元体系汽-液相平衡的热力学模型,本模型假定相同缔合分子间发生二分子、三分子及四分子缔合;不同缔合分子间发生二分子缔合;并考虑了汽相的非理想气体行为。用其计算了二元体系甲酸-水、乙酸-水、丙酸-水、甲酸-乙酸、乙酸-丙酸及甲酸-丙酸的液相活度系数的实验值,其计算值由Wilson方程或McCann方程给出。结果表明,本热力学模型对上述体系是适用的。     

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。     

Aggregation of larvae of the house cricket,Acheta domesticus (L.), by propionic acid present in the excreta

Acetic, propionic, butyric, isobutyric, valeric, and isovaleric acids have been identified in extracts of the excreta of the house cricket,Acheta domesticus (L.), by gas-liquid chromatography. Solutions of propionic acid applied to filter paper aggregated 1- to 2-week-old larvae, while solutions of acetic, butyric, valeric, and isovaleric acids were without effect.     

Vapour-liquid equilibria in associating solutions

Isobaric vapour—liquid equilibria data were measured for the binary mixtures of acetic acid—propionic acid and formic acid—propionic acid at 760 mm Hg. The data were tested against a new thermodynamic model which extends the one proposed by Marek in that it is suitable for the case of binary mixtures containing two associating species and takes into account hetero-dimerization in the vapour phase. The proposed model converts into that of Christian for the particular case of an ideal liquid solution. The model fits well the system acetic acid—propionic acid with regard to the thermodynamic consistency of the overall activity coefficients, but does not fit the second mixture so well, probably because higher degrees of polymerization have to be included in it.     

The effect of liquid phase chemistry on the densification and strength of cold sintered ZnO

Cold sintering is a chemo-mechanical densification process which allows densification of ceramics at low temperatures below 300 °C. This substantial reduction in the sintering temperature is enabled by an externally applied pressure and a compatible transient liquid phase. In this paper, ZnO is cold sintered using various commercial organic acids: formic, acetic and citric acid. The effect of these different transient phases on densification, microstructural evolution and mechanical response is investigated. Fourier transform infrared spectroscopy, thermogravimetric analyses and transmission electron microscopy were conducted to explain the chemical interactions in the cold sintering process. High relative densities (～ 96 %) were achieved by formic and acetic acid, whereas poor densification was obtained for citric acid (< 80 %), despite the higher expected solubility of zinc oxide. The higher biaxial strength found in samples sintered with formic acid compared to acetic acid (i.e. ～90 MPa vs. ～40 MPa) is discussed supported by fractographic analyses.     

Association effects in ternary vapour—liquid equilibria

A thermodynamic model is proposed for the analysis of multicomponent systems capable of homo and heteroassociation between all the chemical species present. Detailed equations have been developed for ternary systems. The method has been applied to the experimental vapour—liquid data obtained for the system formic acid—acetic acid—propionic acid at 760 mm Hg. The calculated activity coefficients were thermodynamically consistent and were correlated using the Redlich—Kister equation. Boiling points, compositions and activity coefficients can be predicted from the vapour—liquid equilibrium data of the three binary systems.     

对苯二甲酸和对羧基苯甲醛在醋酸水溶液中的溶解度

测定了420-505K温度范围内,对苯二甲酸和对羧基苯甲醛在醋酸水溶液中溶解度。在70%-100%醋酸水溶液中,70%醋酸使对苯二甲酸的溶解度对温度最敏感,随着醋酸浓度增加,对苯二甲酸的溶解度减少。当温度低于470K时,对苯二甲酸在水中的溶解性低于醋酸中的溶解度;温度高于470K时,对苯二甲酸在水中的溶解性对温度敏感明显提高。40%醋酸使对羧基苯甲醛的溶解度对温度最敏感, 随着醋酸浓度增加, 对羧基苯甲醛的溶解度增加。实验数据用修正的Apelblat方程进行了对苯二甲酸和对羧基苯甲醛在醋酸水溶液中溶解度关联,计算与实验值吻合良好。     

The lower flash points of binary systems containing non-flammable component

The lower flash points for two binary systems (water+acetic acid and water +propionic acid) containing non-flammable component were measured by Pensky-Martens closed cup tester. The experimental data were compared with the values calculated by the Van Laar and Wilson equations. Good qualitative agreement was obtained with these equations. However, the calculated values based on the Wilson equation were found to be better than those based on the Van Laar equation.     

Preparation of Mullite Fiber

Transparent mullite fibers have been prepared using aluminum carboxylates (ACs) and tetraethyl orthosilicate (TEOS) as starting materials. The ACs are derived from the catalyzed dissolution of elemental aluminum in a mixture of formic acid and acetic acid. The solubility of aluminum in the acids is influenced by the concentrations of the acids, water, and additives and the preparation temperature. A 1:4:3:24 molar ratio of aluminum, formic acid, acetic acid, and water dissolves the aluminum completely to give a colorless, clear solution suitable for fiber synthesis. The mixture of the ACs and TEOS, in the presence of ethyl alcohol as a mutual solvent at 50°–60°C, is concentrated to give a spinnable dope, from which mullite precursor fibers can be drawn. Heat treatment of the precursor at 1250°C yields crystallized and transparent mullite fibers.     

Measurement and correlation for solubility of diosgenin in some mixed solvents简

The solubility data of diosgenin in mixed systems of ethanol ＋ 1-propanol （1 ： 1）, ethanol ＋ 1-butanol （1 ： 1）, ethanol ＋ isobutyl alcohol （1 ： 1）, methanol ＋ isobutyl alcohol （1 ： 1）, methanol ＋ isobutyl alcohol （1 ： 4）, ethanol ＋ 1-pentanol （1 ： 1） and carbon tetrachloride were measured over the temperature range from 289.15 K to 334.15 K by a laser monitoring observation technique at atmospheric pressure, with all mixtures mixed by volume ratio. The Apelblat equation, the ideal solution model, and the 2h equation are used to correlate the solubility data. The results show that the three models agree well with the experimental data, providing essential support for industrial design and further theoretical study.     

Influence of Short-Chain Carboxylic Acids on the Mechanical Properties and Structure of Coagulated Alumina Suspensions

Three different short-chained carboxylic acids, formic, acetic, and propionic acid, were compared as additives to increase the green strength of wet particle networks produced with the direct coagulation casting process, which allows the internal coagulation of a suspension. Small acid additions do not alter the favorable low viscosity of the stabilized slurry, and yet increase the compressive strength of wet coagulated bodies. The strengthening effect increases with increasing chain length of the carboxylic acid. The maximum effect was observed upon addition of propionic acid (0.3 wt% to alumina), which resulted in a sixfold increase in compressive strength of wet coagulated bodies compared with that without propionic acid.     

Phase Equilibria for Ternary Liquid Systems of (Water + Carboxylic Acid + 1‐Heptanol) at 293.15 K: Modelling Considerations

Liquid‐liquid equilibrium data of the solubility curves and tie‐line end compositions are presented for mixtures of [water (1) + formic acid, or acetic acid, or propanoic acid (2) + 1‐heptanol (3)] at T = 293.15 K and P = (101.3 ± 0.7) kPa. The properties and liquid‐liquid equilibria (LLE) of associated ternary systems have been correlated using a solvatochromic approach SERLAS. The tie‐lines were also predicted using the UNIFAC‐original model. The proposed model appears to be an improvement in data fit for the ternary systems yielding a mean error of 3.8% for all the systems considered.     

Short-chain aliphatic acids in the interdigital gland secretion of reindeer (Rangifer tarandus L.), and their discrimination by reindeer

Interdigital gland secretion from reindeer (Rangifer tarandus L.) was analyzed by thin-layer chromatography and gas chromato-graphy. The short-chain acid fraction consisted of acetic, propionic, isobutyric,n-butyric, isovaleric, 2-methylbutyric,n-valeric, isocaproic, andn-caproic acids. The short-chain acids were produced by sterol esters when hydrolyzed in the gland-probably by microorganisms. Triglycerides present did not contain any short-chain acids. By testing isovaleric acid and isobutyric acid applied on small filter papers placed in a pen and measuring the number of sniffings on and towards the samples, we elicited good response at 1 ng application compared with the blanks, while pivalic acid gave no response under the same conditions.     

Prediction and measurement of the lower flash points for flammable binary solutions by using a setaflash closed cup tester

The flash point is one of the most important physical properties used to determine the potential for fire and explosion hazards of industrial materials. The purpose of this study was to measure and predict the lower flash points for the binary mixtures to aid in evaluating the safety of flammable liquid mixtures. The lower flash points for the flammable binary systems, n-hexanol+propionic acid, n-butyric acid+m-xylene and n-pentanol+n-butanol, were measured by Setaflash closed cup tester. The experimentally derived data were correlated with the Wilson and UNIQUAC (UNIversal QUuasi Chemical) equations using the binary interaction parameters. Both equations correlated with a good accuracy.     

内置式连续液-液萃取法对污泥厌氧消化液中挥发性脂肪酸的测定

采用内置式连续液-液萃取、气相色谱内标定量法同时测定厌氧消化液中6种主要VFAs,其中乙酸、丙酸、异丁酸、正丁酸、异戊酸、正戊酸的加标回收率分别为86.7%、93.8%、94.5%、96.2%、103%和107%。样品经萃取后有效去除了无机盐杂质,减小了由直接进样造成的设备损伤,提高了检测数据的准确度和精密度。     

Solubilities of Isophthalic Acid in Acetic Acid + Water Solvent Mixtures

The solubilities of isophthalic acid (1) in binary acetic acid (2)+water (3) solvent mixtures were determined in a pressurized vessel. The temperature range was from 373.2 to 473.2K and the range of the mole fraction of acetic acid in the solvent mixtures was from x₂ 0 to 1. A new method to measure the solubility was developed, which solved the problem of sampling at high temperature. The experimental results indicated that within the temperature range studied, the solubilities of isophthalic acid in all mixtures showed an increasing trend with increasing temperature. The experimental solubilities were correlated by the Buchowski equation, and the calculate results showed good agreement with the experimental solubilities. Furthermore, the mixed solvent systems were found to exhibit a maximum solubility effect on the solubility, which may be attributed to the intermolecular association between the solute and the solvent mixture. The maximum solubility effect was well modeled by the modified Wilson equation.