硫酸钠—过氧化氢—氯化钠加合物的合成研究(Ⅰ)——原料配比对产品产量的影响

利用单因素优选法,研究了288K下用30％的过氧化氢制备硫酸钠—过氧化氢—氯化钠加合物时,氯化钠和硫酸钠的原料配比对产品产量及产品中过氧化氢质量分数的影响。结果表明,氯化钠和硫酸钠的最优质量配比为1:8。在25mL过氧化氢中加入4g NaCl,32g Na_2SO_4,此时产品产量为31.44g,产品中过氧化氢质量分数为9.5％～9.7％,产品颗粒较细。利用二元非线性回归得到了产品产量与硫酸钠和氯化钠加入量关系的数学模型,模型的计算结果与实验值吻合较好,最大偏差为5％。     

钠钙氯化物在乳糖水中热力学性质的确定

在298.15 K时利用电动势法确定四元体系氯化钠-氯化钙-乳糖-水不同组成(乳糖质量分数分别为0,5%,10%和15%)时的热力学性质。利用Pitzer离子作用模型拟合实验数据,获得了氯化钠和氯化钙在乳糖水混合溶剂中的Pitzer模型参数。进一步计算了氯化钠和氯化钙从纯水到乳糖水混合溶剂中的迁移吉布斯函数。获得了氯化钠和氯化钙混合电解质在乳糖水混合溶剂中的混合参数θ(Na Ca)和ψ(Na Ca Cl)。计算了298.15 K时四元体系中氯化钠和氯化钙的平均离子活度系数。结果发现:利用Pitzer高阶静电作用模型计算混合电解质在混合溶剂中的平均离子活度系数,能获得较为满意的结果。     

高温高压下氯化钠水溶液的热力学(Ⅱ)——在823K及100MPa条件下NaCI-H_2O体系的热力学性质

本文将(I)报中提出的简易方程式推广应用到823K和100MPa的NaCl水溶液,NaCl的最高浓度达65.2wt%(三相点时的饱和溶解度)下热力学性质的计算.这些热力学性质包括溶液中水的活度、氯化钠的平均离子活度系数、溶液的Gibbs自由能,计算值与实验值吻合较好.文中列出了不同温度压力下的w和△_8G_2~0/RT值及其变化曲线、和本文提出的参考压力值P_r,为高温高压下电解质水溶液的研究作了初步的探索.     

硫酸—氯酸钠—氯化钠法制二氧化氯工艺条件初探

本文通过滴酸式间歇反应、负压连续吸收产品气体的实验方法,研究了硫酸—氯酸钠—氯化钠法制二氧化氯的初步工艺条件。实验结果表明:采用较高的氯酸钠、氯化钠浓度和适宜的滴酸速度进行反应,可减少耗酸量和获得较高的二氧化氯收率。     

氯化钠在微波干燥中的动态吸波效率研究

为了研究物料在微波干燥过程中的动态吸波效率,文中将反射损耗理论引入其中,计算了2.45 GHz微波频率下,20℃时含水率为1%—5%以及含水率为4%的氯化钠在20—100℃的反射损耗系数。计算结果显示,厚度为0.014 m含水率4%的氯化钠在60℃取得最大的微波吸收效率,达到-68 dB;不同含水率的氯化钠反射损耗系数随着厚度的增加,会按照含水率由高到低的顺序依次出现吸波峰。研究结果表明,只有在对应小于1/8波长的吸收峰偏移的较小厚度下,氯化钠才能在整个微波干燥过程中一直取得较高的吸波效率。     

用BENDER状态方程计算N_2—Ar—O_2体系的热力学参数

Ｂｅｎｄｅｒ状态方程可用于Ｎ_２—Ａｒ—Ｏ_２三元体系，进行热力学性质计算精度较高．本文根据Ｂｅｎｄｅｒ方程推导出焓、熵、比热等热力学参数的计算公式，对Ｎ_２、Ａｒ、Ｏ_２及其混合物进行计算，并与实验数据进行比较，结果令人满意．     

谈谈热力学函数关系式的记忆法

在热力学中,表示热力学函数间关系的热力学方程很多,约有10~7个,这样繁多的力程式,使初学者感到困难。为此,这里介绍一些帮助记忆的简便方法供读者参考。(一)由热力学定律导出的五个最基本的状态函数式,即:H=U PVF=U-TSG=H-TS=U PV-TS=F PV上式中:U—内能,H—焓,S—熵,F—自由能,G—自由焓。上述关系式,曾有几种方法可帮助记忆,但不甚简便。笔者提出“E 形记忆法”等     

曲线拟合技术在计算有机溶剂体系热力学函数中的应用

进行化学、化工计算时,经常需要热力学数据,然而对于有机—水溶剂或非水溶剂体系的热力学数据不仅数据很少,而且计算方法复杂。通过测定电池电动势来计算该体系热力学函数是研究热力学过程的一个十分重要的手段。本文介绍使用曲线拟合技术来确定有机—水溶剂或非水溶剂体系电动势与浓度的关系,以求得标准电动势。根据△Go=-nFE°(其中n—反应的电子得失数;F—法拉第常数;Eo—电池的标准电动势,△Go—体系的标准自由能变化)进而获得体系热力学函数。     

普鲁卡因青霉素的结晶热力学

采用激光测量装置研究了普鲁卡因青霉素在不同温度、不同浓度,不同ｐＨ值的氯化钠水溶液中的溶解与超溶解特性,得到了普鲁卡因青霉素的结晶介稳区。为系统研究普鲁卡因青霉素反应结晶过程提供了一定的热力学基础。     

关于气体热含量计算的讨论

在化工工艺计算中,热量恒算是通过进出某一设备的各组分的热量增加或减少的计算而进行的。在等压过程中,不参加化学反应的某组分热量的计算可表示为:Q_p=G·C_p(t_2-t_1)式中:G——某组分重量;C_P——某组分平均等压比热;     

Temperature dependence of interaction parameters in electrolyte NRTL model

The electrolyte NRTL model captures the electrolyte solution nonideality over the entire concentration range with two binary interaction parameters. Here, the temperature dependence of the binary parameters is formulated with a Gibbs‐Helmholtz expression containing three temperature coefficients associated with Gibbs energy, enthalpy, and heat capacity contributions. We show the Gibbs energy term is correlated to the excess Gibbs energy of aqueous single electrolyte systems at 298.15 K. With the Gibbs energy term identified, the enthalpy term is correlated to the excess enthalpy at 298.15 K. With the Gibbs energy term and the enthalpy term identified, the heat capacity term is correlated to the excess heat capacity at 298.15 K. Once the temperature coefficients are properly quantified by regressing data of mean ionic activity coefficient, excess enthalpy, and heat capacity at 298.15 K or the equivalents, the model provides a comprehensive thermodynamic framework to represent all thermodynamic properties of electrolyte solutions. © 2015 American Institute of Chemical Engineers AIChE J, 62: 1244–1253, 2016     

Correlation of the mean activity coefficient of aqueous electrolyte solutions using an equation of state

Accurate calculation of thermodynamic properties of electrolyte solution is essential in the design and optimization of many processes in chemical industries.A new electrolyte equation of state is developed for aqueous electrolyte solutions.The Carnahan–Starling repulsive model and an attractive term based on square-well potential are adopted to represent the short range interaction of ionic and molecular species in the new electrolyte EOS.The long range interaction of ionic species is expressed by a simplified version of Mean Spherical Approximation theory(MSA).The new equation of state also contains a Born term for charging free energy of ions.Three adjustable parameters of new e EOS per each electrolyte solution are size parameter,square-well potential depth and square-well potential interaction range.The new e EOS is applied for correlation of mean activity coefficient and prediction of osmotic coefficient of various strong aqueous electrolyte solutions at 25 °C and 0.1 MPa.In addition,the extension of the new e EOS for correlation of mean activity coefficient and solution density of a few aqueous electrolytes at temperature range of 0 to 100 °C is carried out.     

Equation of state for the systems containing aqueous salt: Prediction of high pressure vapor-liquid equilibrium

An equation of state (EOS), which is based upon contributions to the Helmholtz energy, is presented for systems containing aqueous electrolyte solutions at high pressure. The Peng-Robinson equation of state is used to provide the Helmholtz energy of a reference system. The electrolyte terms consist three terms containing a modified Debye-Hückel term for long-range electrostatic interactions, the Born energy contribution for electrostatic works and a Margules term for short-range electrostatic interactions between ions and solvents. The binary and ternary interaction parameters of the equation of state are obtained by experimental osmotic coefficient data. Systems that were studied here are (water+ NaCl+SC-CO₂), (water+NH₄Cl+SC-CO₂), (water+Na₂SO₄+SC-CO₂) and (water+methanol+NaCl+SC-CO₂). It is found that the proposed equation of state is able to accurately represent the experimental data over a wide range of pressure, temperature and salt concentration.     

AN EMPIRICAL VIRIAL-LIKE CUBIC EQUATION OF STATE FOR PHASE EQUILIBRIUM CALCULATIONS

An empirical cubic equation of state(EOS) was obtained by truncating the virial expansion in reciprocal of molar volume after the third term. The constants of the EOS was generalized in terms of critical temperature, critical pressure and Pitzer's acentric factor.

In pure component applications the EOS exhibited a performance comparable to Peng-Robinson (1976) EOS in the reduced temperature range of 0.5 to 1. The present EOS tends to predict better saturation liquid volumes at reduced temperatures below 0.8, and better estimations for second virial coefficient at high reduced temperatures.

The EOS was successfully employed for vapor liquid equilibrium calculations for some mixtures of normal or slightly polar fluids with traditional one binary parameter mixing rule at moderately high pressures. At low reduced temperatures, where conventional one adjustable parameter applications of the cubic equations compare unfavorably with dual methods based on excess Gibbs energy functions for the liquid phase, a new two constant mixing rule introduced by Stryjek and Vera (1986) was employed for the present equation of state.     

Association-based activity coefficient model for electrolyte solutions

This work presents an association-based activity coefficient model that explicitly considers the solution nonideality due to associations among ions and solvent species. Built upon the electrolyte nonrandom two-liquid (eNRTL) model, the model greatly improves the accuracy of eNRTL model for strongly associating electrolyte solutions due to presence of ionic species with high surface charge density. The model successfully correlates mean ionic activity coefficients of 46 aqueous single-salt systems from 10 cations and 5 anions at 298.15 K up to their solubility limits. With the ion-specific association parameters identified, the model accurately predicts activity and osmotic coefficients for aqueous mixed-salt systems at 298.15 K. The temperature dependence of the model results has also been examined at 273–373 K. With superior accuracy over a wide range of concentration and temperature, the model represents a major advancement over eNRTL model and has a great potential to be a next-generation model for electrolyte solutions.     

Osmotic coefficients of polyelectrolyte solutions, measurements and correlation

Osmotic coefficient data for aqueous sodium polyanetholesulfonic acid, sodium polyacrylate and polydiallyl dimethylammonium chloride solutions were determined at 298 K by employing the isopiestic method. The measured osmotic coefficients increase with increasing concentration in the experimental concentration range (0.1-1.5 m). A molecular thermodynamic model developed previously for polyelectrolyte solutions has been used to fit the experimental data. The concentration dependence of the osmotic coefficients can be described satisfactorily.     

利用变阱宽方阱链流体状态方程计算1：1电解质溶液热力学性质

将变阱宽方阱链流体状态方程拓展到1：1强电解质水溶液热力学性质的计算中,通过关联溶液的平均离子活度系数和溶剂的渗透系数得到了22种离子的链节直径和方阱能量参数,40余种电解质溶液的平均离子活度系数和溶剂渗透系数的总平均相对偏差分别为6.03%和5.83%。计算结果表明,建立的电解质型状态方程可以满意预测电解质溶液的密度和宽广温度下溶液的蒸气压,总体平均相对偏差分别为0.22%和4.69%。进一步说明模型参数的可靠性。     

水热反应釜中高温高压离子水溶液热力学性质

对水热反应釜中高温高压NaOH和KOH水溶液的热力学性质进行了研究,采用Pitzer表观摩尔体积模型获得了容器中溶液填充度与压力的关系;在考虑溶液中离子缔合现象的基础上对Pitzer活度因子模型进行了改进,建立了能够描述溶液中真实离子组成的NaOH和KOH水溶液热力学模型,并给出了模型参数随温度和压力的变化关系式.计算结果表明,与纯水体系相比,相同反应温度、初始填充度下,NaOH和KOH 水溶液产生的压力显著降低,这意味着实际操作中可以进一步升高反应温度和增加填充度;100℃时,5 mol·kg^-1的NaOH溶液的缔合度就已达到30％,并随反应温度和溶液初始浓度的增加缔合度还将显著升高,表明实际水热反应的氢氧根自由离子浓度远远小于溶液的初始浓度,这为进一步深入研究水热反应机理奠定了理论基础.     

二苯基亚砜在有机溶剂中的溶解度测定和拟合

在温度288.30～334.32 K、常压条件下,采用合成法测定二苯基亚砜在乙醇、乙酸乙酯、甲苯、丙酮、氯仿以及一系列浓度的乙醇-水混合溶剂中的溶解度。实验结果表明,在相同温度下,5种纯溶剂中二苯基亚砜的溶解度大小顺序如下,氯仿 > 丙酮 > 甲苯 > 乙酸乙酯 > 乙醇;乙醇-水混合溶剂中溶解度随着乙醇浓度下降而迅速降低;该溶解过程为吸热熵增过程,且随着溶解Gibbs斯自由能增大,溶解度减小。数据采用改进的Apelblat方程和van’t Hoff方程进行拟合,在乙醇-水混合溶剂中的溶解度数据还采用Jouban-Acree方程拟合。拟合结果与实验数据基本吻合。测定的固液平衡数据可为二苯基亚砜的合成与提纯等过程的溶剂选择提供依据。