P-ρ-T Data and Modeling for Propan-1-ol + n‑Octane or n‑Nonane or n‑Decane from 313.15 K to 363.15 K and 1 MPa to 20 MPa Kuveneshan Moodley,* Suhail Adam, Paramespri Naidoo, Sheriniya Naidu, and Deresh Ramjugernath Thermodynamics Research Unit, School of Engineering, University of KwaZulu-Natal, Howard College Campus, Durban 4041, South Africa ABSTRACT: High-pressure experimental pressure-density-temperature data for the propan-1-ol (1) + n-octane (2), propan-1-ol (1) + n-nonane (2), and propan-1-ol (1) + n-decane (2) binary systems are presented. Measure- ments were conducted over the entire composition range, in the temperature range of 313.15 to 363.15 K, from approximately 1 to 20 MPa, by using an Anton Paar DMA HP densitometer and a newly commissioned pressurizing network. The binary experimental density data is correlated by the five- parameter modified Toscani-Szwarc equation of state, which demonstrates good correlation of the data. Excess molar volumes for the measured systems were determined as a function of pressure and temperature and were found to be positive for the measurement range considered in this work. Derived property data (thermal expansivity and isothermal compressibility) were also calculated for these systems and were found to be nonlinear in most instances. The effects of temperature and pressure on these properties were also discussed. The nonideality of the mixture properties was attributed to differences in the size and shape of the molecules and the energy interactions due to the polarity of the propan-1-ol molecules. 1. INTRODUCTION Density is undoubtedly one of the most significant fluid prop- erties required for the design and simulation of chemical unit operations and processes because it finds application in flow calculations of pipelines, reactors, and columns. Its uses extend to engineering fields such as petroleum exploration, aeronautics, and so forth. Densities of fluid mixtures at varying temperatures and pressures are generally approximated by critical property extrapolations or equations of state (Spencer and Danner 1 ). However, many of the early cubic equations of state fail to pro- vide a good correlation of liquid densities, especially at higher pres- sures and when approaching the critical region (Palenchar et al. 2 ). For common components, an increase in temperature causes a decrease in the fluid density. With increasing pressure, the density usually increases. Some recent studies involving the measurement of densities at elevated pressures include the work of Yang et al., 3 Ahmad et al., 4 Regueira et al., 5 and Safarov et al. 6 When fluid mixtures are considered, the excess volume of the mixture (volume change due to mixing) is often ignored in calcu- lations and can result in large deviations from the real fluid behavior. 7 The effect of temperature on the excess volume is widely accepted and has been studied in great detail. Some data for alkane- and alcohol-containing systems are available in the literature. 8-17 Additionally, numerous pure-component n-octane, n-nonane, n-decane, and propan-1-ol densities have been reported as functions of temperature and pressure in the literature. 18-63 However, the pressure effect on the excess volume is not well studied for the binary propanol-alkane systems considered here. The purpose of this study is to determine the fluid behavior (in view of volumetric properties) of propanol with adjacent alkanes (n-octane, n-nonane, and n-decane) at elevated pres- sures over the entire composition range in the temperature range of 313.15 to 363.15 K at up to 20 MPa. These temperature and pressure ranges were specifically selected because they encompass the conditions of the majority of industrial sepa- ration processes for which these experimental measurements are useful. The dependence of the mixture densities on the tem- perature and pressure are determined through the isothermal compressibility and thermal expansivity, respectively. Such information provides insight into the intermolecular interactions and structural properties of the systems and their components and is essential for high-pressure separation design and flow calculations because any nonidealities associated with elevated pressures must be accounted for in these applications. Further- more, pressure-density-temperature data are essential for the improvement of computational fluid mechanics theory as well as equation-of-state model development (Torcal et al. 62 ). Systems composed of propanol + alkanes are often encountered in the chemical industry and also form a common transport fuel blend in the biofuel industry. The experimental density data were modeled using the modified Toscani-Szwarc equation of state (Zú ñ iga-Moreno et al. 53 ). Received: June 29, 2018 Accepted: September 27, 2018 Article pubs.acs.org/jced Cite This: J. Chem. Eng. Data XXXX, XXX, XXX-XXX © XXXX American Chemical Society A DOI: 10.1021/acs.jced.8b00554 J. Chem. Eng. Data XXXX, XXX, XXX-XXX Downloaded via UNIV OF CAMBRIDGE on October 12, 2018 at 17:24:12 (UTC). See https://pubs.acs.org/sharingguidelines for options on how to legitimately share published articles.