Journal of Chemical Thermodynamics最新文献_第7页

Acoustic, viscometric and spectroscopic study of molecular interactions in butyl acrylate + 1-butanol, + 2-butanol, + 2-methyl-1-propanol, + 2-methyl-2-propanol systems at different temperatures: Experimental and theoretical approach 不同温度下丙烯酸丁酯+ 1-丁醇、+ 2-丁醇、+ 2-甲基-1-丙醇、+ 2-甲基-2-丙醇体系分子相互作用的声学、粘度和光谱研究：实验和理论方法

IF 2.2 3区工程技术 Q3 CHEMISTRY, PHYSICAL

Journal of Chemical Thermodynamics

Pub Date : 2025-06-12 DOI: 10.1016/j.jct.2025.107528

Anil Kumar Nain

The speeds of sound, u and viscosities, η of butyl acrylate +1-butanol/2-butanol/2-methyl-1-propanol/2-methyl-2-propanol binary mixtures across the entire composition range were measured at ambient temperatures and pressure, p = 100 kPa. Using the measured data, viz., excess isentropic compressibilities, excess intermolecular free lengths, excess speeds of sound, excess molar isentropic compressibilities, excess specific acoustic impedances and deviations in viscosity were evaluated. The partial molar isentropic compressibilities and excess partial molar isentropic compressibilities of the components over whole composition range; and at infinite dilution are calculated. The variation of these parameters has been interpreted in relations to intermolecular interactions in these mixtures. The results indicate that the extent of butyl acrylate-alkanol interactions follow the order: 1-butanol >2-butanol >2-methyl-1-propanol >2-methyl-2-propanol. The speeds of sound were theoretically calculated by means of various theories/relations and the viscosities of these mixtures were correlated by means of several empirical and semi-empirical equations and the outcomes are compared with experimental data. The relative applicability of these theories/relations has been discussed. Further to confirm the nature and extent of prevailing intermolecular interactions, the FT-IR spectra of pure butyl acrylate, isomeric butanols and their near equimolar mixtures were recorded and analyzed to validate the prevailing interactions.

在常温、常压（p = 100 kPa）条件下，测定了丙烯酸丁酯+1-丁醇/2-丁醇/2-甲基-1-丙醇/2-甲基-2-丙醇二元混合物在整个组成范围内的声速、u和粘度、η。利用测量数据，即超额等熵可压缩性、超额分子间自由长度、超额声速、超额摩尔等熵可压缩性、超额比声阻抗和粘度偏差进行了评估。组分在整个组成范围内的偏摩尔等熵可压缩性和超偏摩尔等熵可压缩性；在无限稀释下计算。这些参数的变化被解释为与这些混合物中的分子间相互作用有关。结果表明，丙烯酸丁酯与醇的相互作用程度依次为：1-丁醇>；2-丁醇>；2-甲基-1-丙醇>；2-甲基-2-丙醇。利用各种理论/关系对声速进行了理论计算，并用几个经验和半经验方程对这些混合物的粘度进行了关联，并与实验数据进行了比较。讨论了这些理论/关系的相对适用性。为了进一步确认主要的分子间相互作用的性质和程度，我们记录和分析了纯丙烯酸丁酯、异构体丁醇及其近等摩尔混合物的FT-IR光谱，以验证主要的相互作用。

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引用次数: 0

Measurement of critical properties for the binary mixture of R744 (carbon dioxide) + R1233zd(E) (trans-1-chloro-3,3,3-trifluoro-1-propene) R744（二氧化碳）+ R1233zd(E)（反式-1-氯-3,3,3-三氟-1-丙烯）二元混合物临界性能的测定

IF 2.2 3区工程技术 Q3 CHEMISTRY, PHYSICAL

Journal of Chemical Thermodynamics

Pub Date : 2025-06-10 DOI: 10.1016/j.jct.2025.107534

Xiaoyu Yao , Bo Tang , Jinxing Wu , Xueqiang Dong , Qingqing Yang , Huifang Kang , Jun Shen

Due to excellent environmental and thermophysical properties, CO₂ has been used in many areas, such as commercial refrigeration, car air-conditioning, and heat pump drying systems in the past years. However, the low critical temperature and high critical pressure of carbon dioxide limit these applications. A potential approach to address these limitations is to create a mixture of carbon dioxide with other working fluids, such as hydrofluoroolefins or hydrochlorofluoroolefins, which exhibit lower critical temperatures and higher critical pressures. The R744 + R1233zd(E) mixture is a potential alternative working fluid. In this work, the critical properties of R744 + R1233zd(E) binary mixtures including molar composition, critical density, critical temperature, and critical pressure were experimentally measured by a variable volume system with metal bellows. The critical point is determined by judging the intensity of the critical opalescence and the reappearance of the gas-liquid phase interface. Without accounting for the fact that the purity of pure components falls short of 100 %, the combined expanded uncertainty of molar composition, critical temperature, critical density, and critical pressure is (with confidence of 0.95, k value of 2) 0.012, 50 mK, 0.6 %, and 21 kPa. The critical data obtained from the experiment are correlated with the simplified Tang et al.'s model by the Redlich-Kister approach. Both of the two fitting methods can reproduce the critical locus of the R744 + R1233zd(E) binary mixture with high precision. According to the classification of Schneider and van Konynenburg and Scott, the R744 + R1233zd(E) mixture belongs to the first class of type I mixtures, which means the critical locus is a continuous curve, and the critical pressure has a maximum value

由于优异的环境和热物理性能，CO2在过去的几年里已被应用于许多领域，如商用制冷、汽车空调和热泵干燥系统。然而，二氧化碳的低临界温度和高临界压力限制了这些应用。解决这些限制的一个潜在方法是制造二氧化碳与其他工作流体的混合物，如氢氟烯烃或氢氯氟烯烃，它们具有较低的临界温度和较高的临界压力。R744 + R1233zd(E)混合物是一种潜在的替代工作液。本文利用金属波纹管的变容系统，对R744 + R1233zd(E)二元混合物的摩尔组成、临界密度、临界温度和临界压力等临界性能进行了实验测量。通过判断临界乳光的强度和气液相界面的再现来确定临界点。在不考虑纯组分纯度低于100%的情况下，摩尔组成、临界温度、临界密度和临界压力的扩展不确定度（置信度为0.95，k值为2）分别为0.012、50 mK、0.6%和21 kPa。从实验中获得的关键数据通过Redlich-Kister方法与简化的Tang等人的模型相关联。两种拟合方法均能较高精度地再现R744 + R1233zd(E)二元混合物的临界轨迹。根据Schneider和van Konynenburg和Scott的分类，R744 + R1233zd(E)混合物属于第一类I型混合物，即临界轨迹为连续曲线，临界压力有一个最大值

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引用次数: 0

Quaternary system of terephthalic acid +4-carboxybenzaldehyde + p-toluic acid + N-methylpyrrolidone: Mutual solubility determination and correlation together with quantum chemistry research 对苯二甲酸+4-羧基苯甲醛+对甲苯+ n -甲基吡咯烷酮的季元体系：相互溶解度测定及相关性与量子化学研究

IF 2.2 3区工程技术 Q3 CHEMISTRY, PHYSICAL

Journal of Chemical Thermodynamics

Pub Date : 2025-06-06 DOI: 10.1016/j.jct.2025.107533

Min Zheng , Ali Farajtabar , Abolghasem Jouyban , William E. Acree Jr , Hongkun Zhao

At 298.15 Kelvin, the method of isothermal dissolution was utilized in this current work at 101.0 kPa to obtain the experimental solubility data for the quaternary terephthalic acid (TA), p-toluic acid (p-TLA) + 4-carboxybenzaldehyde (4-CBA) + N-methylpyrrolidone (NMP) system. Generation of the quaternary phase diagram was made through the Jãneck approach, which was based on the mutual solubility that was determined. Three zones of neat solid crystallization, one invariant point, along with three co-saturated curves, were included in the quaternary phase diagram. The three solids that were validated by Schreinemaker approach of wet residue were pure p-TLA, pure 4-CBA, and pure TAˑ2NMP, an adduct of TA with NMP with a mole ratio of 1:2. The area where TAˑ2NMP crystallizes is larger compared to that for p-TLA and 4-CBA. In addition, the model of NRTL was used to mathematically correlate and calculate the quaternary solid-liquid phase diagram. The experimental quaternary phase diagram was found to be in good agreement with the computed one obtained from the NRTL model as evidenced by a root-mean-square deviation of 0.14632 and a relative average deviation of 5.01 %. Separating TA from its mixtures by solvent adduct crystallization might be fundamentally supported by the quaternary phase diagram and thermodynamic models. Considering the investigation on the independent gradient model based on Hirshfeld partitions, as well as the 2D fingerprint plot and difference map of electron density, density difference and difference map of ELF analysis, the van der Waals forces are viewed as favorable weak interactions during the process of forming the adduct of TAˑ2NMP.

本文采用等温溶解法，在298.15开尔文温度下，在101.0 kPa下获得了季对苯二甲酸（TA）、对甲苯(p-TLA) + 4-羧基苯甲醛(4-CBA) + n -甲基吡咯烷酮（NMP）体系的实验溶解度数据。通过j颈法生成四元相图，该方法基于确定的相互溶解度。在四元相图中包括三个纯固体结晶区、一个不变点和三条共饱和曲线。湿残渣Schreinemaker法验证的三种固体为纯p-TLA、纯4-CBA和纯TA与NMP的加合物（摩尔比为1:2）。与p-TLA和4-CBA相比，TA α - 2NMP的结晶面积更大。此外，利用NRTL模型进行了第四元固液相图的数学关联和计算。实验得到的四元相图与NRTL模型计算得到的四元相图吻合较好，均方根偏差为0.14632，相对平均偏差为5.01%。用溶剂加合结晶法分离TA和TA的混合物可能从根本上得到了四元相图和热力学模型的支持。基于Hirshfeld划分的独立梯度模型的研究，以及电子密度的二维指纹图和差图、密度差图和ELF分析的差图，认为在TA α 2 - nmp加合物形成过程中，范德华力是有利的弱相互作用。

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引用次数: 0

Volumetric, transport and acoustic properties of [4-methyl-2-pentanol + 2-methoxyethanol, or 2-(2-methoxyethoxy)ethanol, or 2-{2-(2-methoxyethoxy)ethoxy}ethanol] at varying temperatures [4-甲基-2-戊醇+ 2-甲氧基乙醇，或2-（2-甲氧基乙氧基）乙醇，或2-{2-（2-甲氧基乙氧基）乙氧基}乙醇]在不同温度下的体积、传输和声学特性

IF 2.2 3区工程技术 Q3 CHEMISTRY, PHYSICAL

Journal of Chemical Thermodynamics

Pub Date : 2025-06-06 DOI: 10.1016/j.jct.2025.107531

Rachana Singh, Gyan Prakash Dubey

Density (

ρ

), viscosity (

η

) and speed of sound (u) of pure components and binary mixtures of 4-methyl-2-pentanol with alkoxyethanols viz., 2-methoxyethanol, 2-(2-methoxyethoxy)ethanol and 2-{2-(2-methoxyethoxy)ethoxy}ethanol have been measured at T = (298.15, 303.15, 308.15) K over the entire range of composition at pressure p = 0.10 MPa. Thermodynamic properties such as excess molar volume (

V_{m}^{E}

), excess molar isentropic compressibility (

K_{s, m}^{E}

), deviation in speed of sound (

u^{D}

), deviation in viscosity (Δη) and excess Gibbs free energy of activation for viscous flow (

Δ G^{* E}

) have been calculated using experimental data. The interaction between like and unlike molecules can be described using the excess or deviation properties. The Redlich-Kister polynomial equation has been used to correlate the values of the excess and deviation properties. Further, density values were used to calculate partial molar volumes (

{\bar{V}}_{m, i}

). Various semi-empirical relations have been considered to correlate the measured viscosities, including Grunberg-Nissan, Tamura-Kurata, Hind et al., Katti-Chaudhri, McAllister (three body interaction) model, Heric-Brewer and McAllister (four body interaction) model. In addition, Prigogine-Flory-Patterson (PFP) theory is used to obtain the

V_{m}^{E}

values. The results obtained are discussed in term of intermolecular interactions taking place between the molecules of liquid components under investigation.

在T = (298.15, 303.15, 308.15) K下，在压力p = 0.10 MPa下，测量了4-甲基-2-戊醇与烷氧乙醇的纯组分和二元混合物，即2-甲氧基乙醇、2-（2-甲氧基乙氧基）乙醇和2-{2-（2-甲氧基乙氧基）乙氧基}乙醇的密度（ρ）、粘度（η）和声速(u)。热力学性质，如超额摩尔体积（VmE），超额摩尔等熵压缩性（Ks,mE），在声速偏差（uD），在粘度偏差（Δη）和超额吉布斯自由能活化粘性流动（ΔG * E）已计算使用实验数据。相似分子和不同分子之间的相互作用可以用过量或偏差特性来描述。用Redlich-Kister多项式方程来关联超差和偏差特性的值。此外，密度值用于计算偏摩尔体积（V¯m,i）。已经考虑了各种半经验关系来关联测量的粘度，包括Grunberg-Nissan， Tamura-Kurata， Hind等人，Katti-Chaudhri, McAllister（三体相互作用）模型，herc - brewer和McAllister（四体相互作用）模型。此外，采用PFP （Prigogine-Flory-Patterson）理论计算了VmE值。从分子间相互作用的角度对所得结果进行了讨论。

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引用次数: 0

Thermogravimetric kinetic study of catalytic and non-catalytic pyrolysis of PET bottles and micro carbon rod formation PET瓶催化与非催化热解及微碳棒形成的热重动力学研究

IF 2.2 3区工程技术 Q3 CHEMISTRY, PHYSICAL

Journal of Chemical Thermodynamics

Pub Date : 2025-06-01 DOI: 10.1016/j.jct.2025.107530

Parul Dwivedi, Ashwani Kumar Rathore

This study examined the thermogravimetric pyrolysis behaviour of Polyethylene Terephthalate (PET) bottles using catalysts like ferrocene (F), red mud (RM), a Ni/Cu/Mo multicomponent catalyst on kieselguhr, and ferrocene-red mud mixtures, with or without hydrogen peroxide. Heating rates of 10, 20, and 30 °C/min were used. The Kissinger–Akahira–Sunose (KAS) and Flynn–Wall–Ozawa (FWO) models determined activation energies (Ea), which were lower with catalysts compared to pure PET (189 kJ/mol). The lowest Ea (53 kJ/mol) was achieved with hydrogen peroxide, resulting in complete pyrolysis and no char. SEM analysis of the resulting char showed micro carbon rod (MCR) formations. The best catalyst can be chosen based on the needs of the final product. For example, if MCR creation is the goal, ferrocene and red mud may be the best choice; if full pyrolysis is the goal, H₂O₂ may provide the greatest result. The thermodynamic analysis, including ΔH, ΔG, and ΔS, indicated that the enthalpy values for catalyst-containing PETs are lower than those for pure PET. This suggests that the synergistic effect of catalytic pyrolysis likely reduces the energy required to form the activated complex during the thermal decomposition of PET.

本研究使用二茂铁(F)、赤泥（RM）、镍/铜/钼多组分催化剂（kieselguhr）和二茂铁-赤泥混合物等催化剂，在有或没有过氧化氢的情况下，研究了聚对苯二甲酸乙二醇酯（PET）瓶的热重热解行为。加热速率分别为10、20和30°C/min。采用Kissinger-Akahira-Sunose （KAS）和Flynn-Wall-Ozawa （FWO）模型测定的活化能（Ea）低于纯PET （189 kJ/mol）。过氧化氢的Ea最低（53 kJ/mol），热解完全，无焦。扫描电镜分析结果表明，炭中存在微碳棒（MCR）。可根据最终产物的需要选择最佳催化剂。例如，如果目标是创造MCR，二茂铁和赤泥可能是最佳选择；如果目标是充分热解，H2O2可能提供最大的结果。热力学分析（ΔH， ΔG和ΔS）表明，含催化剂PET的焓值低于纯PET。这表明催化热解的协同作用可能降低了PET热分解过程中形成活化配合物所需的能量。

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引用次数: 0

Thermodynamics of hydroxylbastnaesite 羟基氟碳醚的热力学

IF 2.2 3区工程技术 Q3 CHEMISTRY, PHYSICAL

Journal of Chemical Thermodynamics

Pub Date : 2025-06-01 DOI: 10.1016/j.jct.2025.107529

G.A. Agbanga , M. Scharrer , C.G. White , B.F. Woodfield , A. Navrotsky

The mineral bastnaesite, REECO₃[F, OH] (REE = rare earth elements), is a major source of rare earth elements and can be found in commercial deposits such as Mountain Pass, California, and Bayan Obo, China. In addition, its natural and synthetic forms have been explored for applications in optical devices, phosphors, batteries, ceramics, and magnets, accounting for 41 % of the world's consumption of rare earth elements. Therefore, investigating and analyzing thermodynamic properties of REE minerals are crucial for understanding origin, improving extraction processes, and optimizing industrial applications. This study presents a detailed reevaluation of structural and thermodynamic properties of well-characterized synthetic hydroxyl bastnaesite compounds: LaCO₃OH, PrCO₃OH, NdCO₃OH, SmCO₃OH, and EuCO₃OH. Their standard enthalpies of formation (ΔH⁰_f) were determined by high temperature oxide melt solution calorimetry and standard entropy (S⁰) was obtained from low temperature heat capacity (c_p) measurement from 1.8 to 300 K, extrapolated to 600 K combined the Einstein and Debye models. These allowed calculation of the Gibbs energy of formation (ΔG⁰_f). Extrapolation of thermodynamic properties to the heavy REEs by relation to the ionic radius of the REE³⁺ cation and to higher temperatures using the experimental c_p fit provides stability constraints for hydroxylcarbonates allowing for modelling REE-H₂O-CO₂ systems.

矿物氟碳铈矿REECO3[F， OH] （REE = rare earth elements）是稀土元素的主要来源，可在加州帕斯山（Mountain Pass）和中国白云鄂博（Bayan Obo）等商业矿床中发现。此外，在光学器件、荧光粉、电池、陶瓷和磁体等方面，其天然和合成形式的应用已被探索，占世界稀土元素消费量的41%。因此，研究和分析稀土矿物的热力学性质对于了解稀土矿物的来源、改进提取工艺和优化工业应用至关重要。本研究对表征良好的合成羟基氟碳醚化合物LaCO3OH、PrCO3OH、NdCO3OH、SmCO3OH和EuCO3OH的结构和热力学性质进行了详细的重新评价。它们的标准生成焓（ΔH0f）由高温氧化物熔体溶液量热法测定，标准熵（S0）由1.8至300 K的低温热容（cp）测量得到，并结合爱因斯坦和德拜模型外推至600 K。这样就可以计算吉布斯生成能（ΔG0f）。通过与REE3+阳离子的离子半径和使用实验cp拟合的较高温度的关系来推断重稀土的热力学性质，为羟基碳酸盐提供了稳定性约束，允许对REE-H2O-CO2体系进行建模。

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引用次数: 0

Determination and correlation of liquid-liquid equilibrium data for separation of cyclohexane + isopropyl alcohol systems with different extractants 不同萃取剂分离环己烷+异丙醇体系液液平衡数据的测定及相关性研究

IF 2.2 3区工程技术 Q3 CHEMISTRY, PHYSICAL

Journal of Chemical Thermodynamics

Pub Date : 2025-05-28 DOI: 10.1016/j.jct.2025.107525

Fangfang Dai, Meiyuan Peng, Chen Wang, Kang Zhang

In this work, ethylene glycol (EG), formamide, and 1, 2-propanediol were identified as potential extractants for separating cyclohexane + isopropanol (IPA) azeotropic system. The σ-profile was analyzed using the Dmol³ module of Materials Studio, and the interaction energy between the components was calculated, indicating that EG is the most promising extractant. The liquid-liquid equilibrium (LLE) data for the cyclohexane + IPA + extractants system were measured at 303.15 K, 313.15 K and 323.15 K. When the temperature increases, the extraction capacities of EG and formamide decrease. Meanwhile, the temperature has less impact on the capacity of 1, 2-propanediol. EG has higher value of the distribution coefficient (D) and separation factor (S), indicating its superior effectiveness for separation. Othmer-Tobias and Hand equations were used to estimate the reliability and consistency of the LLE data. The nonrandom two-liquid (NRTL) and universal quasi-chemical (UNIQUAC) thermodynamic model in Aspen Plus 11 software were used to regress the LLE data, and the binary interaction parameters were calculated. The root mean square deviation (RMSD) values were all less than 0.02, indicating that the NRTL and UNIQUAC models can correlate experimental data well. Finally, the regressed binary interaction parameters were further validated using GUI-MATLAB software, confirming the reliability of the data regression.

本研究确定了乙二醇（EG）、甲酰胺和1,2 -丙二醇作为分离环己烷+异丙醇（IPA）共沸体系的萃取剂。采用Materials Studio的Dmol3模块对萃取剂的σ-谱进行了分析，并计算了各组分之间的相互作用能，结果表明EG是最有前途的萃取剂。在303.15 K、313.15 K和323.15 K下，测定了环己烷+ IPA +萃取剂体系的液液平衡（LLE）数据。随着温度的升高，EG和甲酰胺的提取率降低。同时，温度对1,2 -丙二醇的容量影响较小。EG的分布系数(D)和分离因子(S)值较高，表明其具有较好的分离效果。使用other - tobias和Hand方程来估计LLE数据的可靠性和一致性。利用Aspen Plus 11软件中的非随机双液体（NRTL）和通用准化学（UNIQUAC）热力学模型对LLE数据进行回归，计算二元相互作用参数。均方根偏差（RMSD）值均小于0.02，表明NRTL和UNIQUAC模型能较好地关联实验数据。最后，利用GUI-MATLAB软件对回归的二元交互参数进行进一步验证，验证了数据回归的可靠性。

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引用次数: 0

Volumetric, FT-IR, and optical properties of 2–amino-1-butanol with isomeric butanol at 298.15 K–318.15 K using PFP theory and graph theoretical approach 298.15 K - 318.15 K下2 -氨基-1-丁醇与异构体丁醇的体积、FT-IR和光学性质应用PFP理论和图理论方法

IF 2.2 3区工程技术 Q3 CHEMISTRY, PHYSICAL

Journal of Chemical Thermodynamics

Pub Date : 2025-05-27 DOI: 10.1016/j.jct.2025.107524

Sweety Verma , Kavitha Kumari , Suman Gahlyan , Ji Hoon Kim , Juwon Min , Sanjeev Maken

The density and optical properties of binary mixtures containing 2–amino 1–butanol (2AB) and isomeric butanol were measured over a temperature range (298.15–318.15) K and 0.1 MPa pressure. Using these measurements, excess molar volume (

{V_{m}}^{E}

) and deviation in refractive index (

Δ n_{D}

) were computed. The negative

{V_{m}}^{E}

values, at equimolar composition, follow the order: tert-butanol > sec-butanol > isobutanol > n-butanol, while the

Δ n_{D}

exhibit the opposite trend. The Prigogine–Flory–Patterson theory and the Graph theoretical approach were applied to interpret the

{V_{m}}^{E}

data at 298.15 K, respectively. Moreover, the molecular species of various components are predicted to exist in both pure and mixed states by the GTA. Furthermore, FT–IR spectroscopy confirmed the formation of hydrogen bonding between the molecules of the components. The

{V_{m}}^{E}

values decrease with increasing temperature, while the

Δ n_{D}

values increase with increasing temperature. Various mixing rules were applied to calculate

n_{D}

theoretically. This study aims to expand the database of thermophysical properties for amine-alcohol mixtures, providing a reference for engineers and scientists developing advanced CO₂ capture technologies.

在298.15 ~ 318.15 K的温度范围和0.1 MPa的压力下，测定了含有2 -氨基- 1 -丁醇（2AB）和异构丁醇二元混合物的密度和光学性质。利用这些测量，计算了多余摩尔体积（VmE）和折射率偏差（ΔnD）。在等摩尔组成下，负的vmev值依次为：叔丁醇>；进行比;异丁醇的在正丁醇，而ΔnD则呈现相反的趋势。应用Prigogine-Flory-Patterson理论和Graph理论方法分别解释298.15 K的VmE数据。此外，GTA还预测了各种组分的分子种类在纯态和混合态下都存在。此外，FT-IR光谱证实了组分分子之间形成了氢键。VmE值随温度升高而减小，ΔnD值随温度升高而增大。在理论计算中采用了不同的混合规则。本研究旨在扩充胺醇混合物的热物理性质数据库，为工程师和科学家开发先进的CO2捕集技术提供参考。

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引用次数: 0

A simplified method for enhanced accuracy in calculating adsorption thermodynamic parameters 一种提高吸附热力学参数计算精度的简化方法

IF 2.2 3区工程技术 Q3 CHEMISTRY, PHYSICAL

Journal of Chemical Thermodynamics

Pub Date : 2025-05-22 DOI: 10.1016/j.jct.2025.107517

Tijana Ivanović , Tijana Tomović , Daniela Popović , Jelena Miladinović , Mouad Arrad , Zoran Miladinović

This study investigates the thermodynamic parameters of phosphate adsorption on activated carbon using the Pitzer ion-interaction model. The adsorption data were analyzed using the Langmuir and Sips models, both providing satisfactory fits. Maximum adsorption (plateau) occurred at an equilibrium phosphate concentration of 60.8 mmol⋅ dm⁻³ (pH = 5.1), with an adsorption capacity of 7.03 mmol⋅g⁻¹. The Pitzer model was used to calculate the activity coefficient of phosphates, considering the influence of all ions in the solution on the adsorption plateau. The maximum degree of dissociation of H₂PO₄^-(aq) ions was determined to be x_d(2) = 0.0026, taking hydrolysis into account. The activity coefficient of KH₂PO₄ in the mixed solution {K₂HPO₄ + KH₂PO₄ + H₃PO₄}(aq) was found to be γ_± = 0.7788, while in a pure KH₂PO₄ solution at the same ionic strength corresponding to the plateau, it is γ_± = 0.7790. Given the minor difference in activity coefficient, the mixed solution could be approximated as a pure KH₂PO₄(aq) for thermodynamic analysis, which greatly simplified the calculations. The Gibbs free energy was ΔG_L = − 8.6200 ± 0.0004 (kJ⋅mol⁻¹) using the Langmuir equilibrium constant shifting to ΔG_a = − 9.240 ± 0.006 (kJ⋅mol⁻¹) when accounting for activity coefficient and the thermodynamic equilibrium constant. With the Sips model, the Gibbs free energy was ΔG_S = − 9.620 ± 0.004 (kJ⋅mol⁻¹) and further refinement using phosphate activity coefficient gave ΔG_a = −10.235 ± 0.007 (kJ⋅mol⁻¹). The absolute differences in adsorption energy were approximately 7 % (Langmuir) and 6 % (Sips), highlighting the importance of considering ionic activities.

采用Pitzer离子相互作用模型研究了活性炭吸附磷酸盐的热力学参数。采用Langmuir模型和Sips模型对吸附数据进行了分析，两者的拟合结果都令人满意。磷酸盐平衡浓度为60.8 mmol⋅dm−3 （pH = 5.1）时吸附量最大，吸附量为7.03 mmol⋅g−1。考虑溶液中各离子对吸附平台的影响，采用Pitzer模型计算磷酸盐的活度系数。考虑水解作用，确定H₂PO₄-(aq)离子最大解离度为xd(2) = 0.0026。在混合溶液（K₂HPO₄+ KH₂PO₄+ H₃PO₄）中，KH₂PO₄的活度系数（aq）为γ±= 0.7788，而在离子强度相同的纯KH₂PO₄溶液中，其活度系数为γ±= 0.7790。由于活度系数相差不大，混合溶液可以近似为纯KH₂PO₄（aq）进行热力学分析，大大简化了计算。考虑活度系数和热力学平衡常数，使Langmuir平衡常数变为ΔGa =−9.240±0.006 (kJ·mol−1)，Gibbs自由能为ΔGL =−8.6200±0.0004 （kJ·mol−1）。在Sips模型下，Gibbs自由能为ΔGS =−9.620±0.004 (kJ·mol−1)，利用磷酸活度系数进一步精化得到ΔGa =−10.235±0.007 （kJ·mol−1）。吸附能的绝对差异约为7% （Langmuir）和6% (Sips)，突出了考虑离子活性的重要性。

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引用次数: 0

Impact of viscosity index modifiers with different architectures and functionalities on the thermophysical properties and viscosity of a mineral base oil 不同结构和功能的粘度指数改进剂对矿物基础油热物性和粘度的影响

IF 2.2 3区工程技术 Q3 CHEMISTRY, PHYSICAL

Journal of Chemical Thermodynamics

Pub Date : 2025-05-22 DOI: 10.1016/j.jct.2025.107516

Katrina Avery , Melanie Lindblom , Liza Peoples , Erdogan Kiran , Mark T. Devlin

This study examines the influence of viscosity index modifiers on the high-pressure and temperature thermophysical and rheological properties of a mineral base oil, Ultra S4. The viscosity index modifiers tested included polymethacrylates, ethylene-propylene block copolymers and star-styrene butadiene copolymers. Densities were determined at pressures in the range of 10–35 MPa and at 298, 323, 348, 373, and 398 K using a high-pressure variable-volume view-cell. The density data were then correlated with the Sanchez-Lacombe Equation of State from which the thermodynamic properties of isothermal compressibility, isobaric expansivity and internal pressure were derived. Viscosities were determined at pressures in the range of 10–45 MPa and at 298, 323, 348 and 373 K using a uniquely designed high-pressure rotational viscometer. High pressure density and viscosity results were correlated with free volume and density-scaling equations to provide further insight into molecular packing and interactions. Additionally, intrinsic viscosity measurements were performed to evaluate the semi-dilute regime and the radius of gyration at 30 °C and 50 °C.

本研究考察了粘度指数调节剂对矿物基础油Ultra S4高压和高温热物理和流变性能的影响。测试的粘度指数改性剂包括聚甲基丙烯酸酯、乙烯-丙烯嵌段共聚物和星型苯乙烯-丁二烯共聚物。在10-35 MPa和298、323、348、373和398 K的压力范围内，使用高压变体积观察池测定密度。然后将密度数据与Sanchez-Lacombe状态方程相关联，由此导出等温压缩率、等压膨胀率和内压的热力学性质。在10-45 MPa和298、323、348和373 K的压力范围内，使用独特设计的高压旋转粘度计测量粘度。高压密度和粘度结果与自由体积和密度缩放方程相关联，从而进一步了解分子堆积和相互作用。此外，还进行了特性粘度测量，以评估半稀释状态和30 °C和50 °C时的旋转半径。

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引用次数: 0