Henry's Law Research Articles

Transport parameter effects on controlling formation and shape of lotus-type pores in solid

Abstract This study explores sufficient conditions based on transport parameters to effectively manipulate the growth and shape of lotus pores during solidification. Specifically, spatial variations in mass transfer coefficients and solute transport parameters are considered. Solute transport is the key factor responsible for the evolution of lotus pores. The work investigates the influence of these conditions on the shape development of lotus pores, which find applications in diverse fields such as energy absorption, sound absorption, shock and vibration damping, heat sinks, filters and tissue and bone implants. The unsteady gas pressure within the pores, responsible for bubble entrapment, is influenced by gas, capillary and liquid pressures, as well as Sieverts’ or Henry's laws, and solute transfer at gas–liquid interfaces. Solute transport into the pore is determined by liquid convection as well as convection-affected segregation at the advancing liquid–solid interface. The study utilizes the MATLAB code to solve the resulting first-order time-derivative ordinary differential equations. It shows that the lotus pores are susceptible to entrapment as the mass transfer coefficient at a contact angle of 90° increases, while the solute transport parameters at the initial time and a contact angle of 90° decrease. The lotus pore length increases and decreases, respectively, with increases in the mass transfer coefficients as well as the solute transport parameter at the initial time and a contact angle of 90°. Predicted lotus pore shapes align closely with algebraic results, validated by experimental data from a prior study.

Sorption of gases by disordered materials: A model based on the glass transition effect

Disordered materials in the glassy state show different gas sorption properties compared to same materials in the liquid or rubbery state. The sorption enthalpy becomes more exothermic, and the absorbed amount is greater compared to the liquid or rubbery state. The sorption data are often treated in the literature using the dual-mode theory—a three-parameter sorption model. This work presents another approach where a gas sorption isotherm model for glassy materials is derived from thermodynamic consideration of glass transition properties. The model is particularly applicable for describing sorption data that obey Henry's law in the limit of the liquid or rubbery state. The model parameters correspond to physically meaningful characteristics of the system's glass transition. We demonstrate that experimental gas sorption data, when plotted as ln(P/C) vs C, exhibit linear behavior in both the rubbery and glassy states, enabling accurate determination of the glass transition point from isothermal data. Additionally, gas sorption in glassy disordered materials can be effectively described using a two-parameter function based on the Lambert W function.

Construction and evaluation of an open-source database for inhalation-based physiologically based kinetic modeling of selected categories for industrial chemicals

A physiologically based kinetic (PBK) model is used for predicting chemical concentrations of toxicological concern in target tissues. Such models are important for understanding toxicokinetics. However, it is challenging to obtain chemical-specific empirical parameter values used for PBK modeling. Thus, developing methods predicting these values is necessary. Herein, we researched PBK models of inhalation exposure to industrial chemicals and developed a database of parameters of approximately 200 chemicals in humans and rodents. Next, the chemicals in the database were classified into three categories (I, IIA, and IIB) based on the intermolecular interactions for humans and rats. Quantitative relationships between blood/air and tissue/blood partition coefficients and physicochemical parameters were derived for the chemicals in each category. Regression analyses of blood/air and fat/blood partition coefficients against Henry's law constant and log D at pH 7.4 for chemicals in category IIA for humans, in which van der Waals and dipole-dipole interactions were involved, yielded 0.88 and 0.54 coefficients of determination, respectively. Moreover, these methods worked for other categories and species. The metabolic parameters maximal velocity (Vmax) and Michaelis-Menten constant (Km) of the chemicals that are primarily metabolized by cytochrome P450 were calculated for humans and rats. Multiple regression analyses of logs Vmax and Km against the occurrence frequency of molecular fragments showed good correlations, respectively. The aforementioned models predicted values close to the reported values for test chemicals within the applicability domains. Our approach could also be applied to other chemicals within the domains that are not included in the database.

Prediction of Temperature-Dependent Henry's Law Constants by Matrix Completion.

Methods for predicting Henry's law constants Hij describing the solubility of solutes i in solvents j as a function of temperature are essential in chemical engineering. While isothermal properties of binary mixtures can conveniently be predicted with matrix completion methods (MCMs) from machine learning, we advance their application to the temperature-dependent prediction of Hij in the present work by combining them with physical equations describing the temperature dependence. For training the methods, experimental Hij data for 122 solutes and 399 solvents ranging from 173.15 to 573.15 K were taken from the Dortmund Data Bank. Two MCMs are proposed: a data-driven MCM that relies solely on experimental data and a hybrid MCM that incorporates predictions from the established Predictive Soave-Redlich-Kwong (PSRK) equation of state (EoS), effectively combining physical knowledge and machine learning. The performance of these MCMs is assessed via leave-one-out analysis and compared to that of the PSRK-EoS, demonstrating superior prediction accuracy.

Retention of α-pinene oxidation products and nitro-aromatic compounds during riming

Abstract. Riming is an important growth process of graupel and hailstones in the mixed-phase zones of clouds, during which supercooled liquid droplets freeze on the surface of ice particles by contact. Compounds dissolved in the supercooled cloud droplets can remain in the ice or be released to the gas phase during freezing, which might play an important role in the vertical redistribution of these compounds in the atmosphere by convective cloud processes. This is important for estimating the availability of these compounds in the upper troposphere, where organic matter can promote new particle formation and growth. The amount of organic material remaining in the ice phase can be described by the retention coefficient. Experiments were performed in the Mainz vertical wind tunnel under dry and wet growth conditions (temperature from −12 to −3 °C and a liquid water content (LWC) of 0.9±0.2 g m−3 and 2.2±0.2 g m−3) as well as with different pH values (4 and 5.6) to obtain the retention coefficients of α-pinene oxidation products and nitro-aromatic compounds. For cis-pinic acid, cis-pinonic acid, and (−)-pinanediol, mean retention coefficients of 0.96±0.07, 0.92±0.11, and 0.98±0.08 were obtained. 4-Nitrophenol, 4-nitrocatechol, 2-nitrobenzoic acid, and 2-nitrophenol showed mean retention coefficients of 1.01±0.07, 1.01±0.14, 0.99±0.04, and 0.21±0.12. Only the retention coefficient of 2-nitrophenol showed a dependence on temperature, growth regime, and pH. This is in accordance with previous studies, which showed a dependence between the dimensionless effective Henry's law constant H* and the retention coefficient for inorganic and small organic molecules. Our results reveal that this correlation can also be applied to more complex organic molecules and that retention under these conditions is not a significant factor for molecules with H* below 103, while retention close to 1 can be expected for compounds with H* above 108.

A pair of entrapping or coalescing bubbles affected by convection during downward solidification

In this study, the development of solute concentration and velocity fields of a pair of entrapping or coalescing bubbles during downward solidification is provided. The gas-induced pores in the metal not only deteriorates the properties of the processed workpiece by causing stress concentration and defects within the material, but pore formation in sea ice also plays an important role in global warming. Using COMSOL Multiphysics version 5.2, the unsteady, two-dimensional transport equations of mass, momentum, energy, and concentration are solved. The results show that bubble coalescence is facilitated by decreasing solid thermal conductivity and interpore spacing. Unlike the symmetric distribution of concentration observed with a low Henry's law constant and liquid solute diffusivity, an asymmetric distribution occurs, with high and low concentration gradients near the leading and rear edges of each bubble, respectively, due to the liquid velocity from the upstream direction. An outward flow in the opposite direction occurs near the triple-phase line, resulting in an inflection region in the iso-concentration field. The thickness of the concentration boundary layer surrounding the pores also decreases with decreasing Henry's law constant and liquid solute diffusivity, as well as with increasing ambient pressure, gravitational acceleration, solid thermal conductivity, and surface tension. The predicted contact angle during solidification aligns well with Abel's equation. Solute segregation associated with the formation of multiple pores can be controlled.

Kr Adsorption in Porous Carbons: Temperature-Dependent Experimental and Computational Studies†.

The temperature dependence of the adsorption energy of krypton adsorption on activated carbon materials was studied by experiment and simulation. Adsorption isotherms were measured at temperatures from 250 to 330 K and analyzed with Henry's law. The adsorption energy determined from these measurements was found to weaken by more than 10% in this range. Slit pore widths for simulations in this work were modeled by the removal of integral numbers of planes in graphite. Vibrational dynamics of the krypton adsorbate and the carbon atom adsorbent were calculated with the stochastic temperature-dependent effective potential (sTDEP) method, using energetics from density functional theory (DFT) with the many-body dispersion energy method (MBD). Thermal displacements of carbon atoms had a negligible effect on the adsorption energy. The width of the slit pore had the greatest effect on the surface dynamics and the energies of the adsorbate atoms at different temperatures. Assuming a distribution of pore widths, the Boltzmann distribution of site occupancies causes a large weakening of the thermally averaged adsorption energy at higher temperatures.

Positive Feedback between Partitioning of Carbonyl Compounds and Particulate Sulfur Formation during Haze Episodes.

Carbonyl compounds are important precursors of aqueous aerosols in the atmosphere, while their gas-particle partitioning behaviors and roles in particulate sulfur formation are poorly understood. In this study, we investigate the partitioning of five carbonyl compounds (formaldehyde, acetaldehyde, acetone, glyoxal, and methylglyoxal) during haze episodes in Beijing, China. On haze days, the values of field-derived effective Henry's law coefficients (KHf) on aerosols for these carbonyl compounds are 106-108 M atm-1, which are significantly higher (102-104 times) than those in pure water. Sulfate is observed to have a pronounced "salting-in" effect on these carbonyl compounds, resulting in at least 1-order-of-magnitude increase in their particle-phase concentrations. Parameterization schemes for their partitioning in the ambient aerosols were provided and applied to the multiphase chemical box model (RACM2-CAPRAM). When incorporated into the field-derived parametrization, the model significantly increased hydroxymethanesulfonate (HMS) production by 50-fold compared to using the parameters obtained in pure water, increasing from 2.6 × 10-2 to 1.23 μg m-3 h-1. The formed HMS can facilitate sulfate formation in turn through further oxidation by OH radicals and enhance aerosol hygroscopicity. These findings indicate a positive feedback loop between the partitioning of carbonyl compounds and particulate sulfur formation during haze episodes, providing new insights for controlling particulate pollution and reducing SO2 levels in urban areas.

A QSPR Model for Henry's Law Constants of Organic Compounds in Water and Ethanol for Distilled Spirits.

Henry's law describes the vapor-liquid equilibrium for dilute gases dissolved in a liquid solvent phase. Descriptions of vapor-liquid equilibrium allow the design of improved separations in the food and beverage industry. The consumer experience of taste and odor are greatly affected by the liquid and vapor phase behavior of organic compounds. This study presents a machine learning (ML) based model that allows quick, accurate predictions of Henry's law constants (kH) for many common organic compounds. Users input only a Simplified Molecular-Input Line-Entry System (SMILES) string or a common English name, and the model returns Henry's law estimates for compounds in water and ethanol. Training was performed on 5,690 compounds. Training data were gathered from an existing database and were supplemented with quantum mechanical (QM) calculations. An extra trees regression model was generated that predicts kH with a mean absolute error of 1.3 in log space and an R2 of 0.98. The model is applied to common flavor and odor compounds in bourbon whiskey as a test case for food and beverage applications.

The pKa of Water and the Fundamental Laws Describing Solution Equilibria: An Appeal for a Consistent Thermodynamic Pedagogy

AbstractA recurring misconception in some textbooks and research papers has led to an abandonment of fundamental physical laws when describing a subset of acid‐base equilibria, especially regarding the role of the solvent. In the specific case of the autoprotolysis of water, experiments and theoretical calculations prove that the Kw of water at 25 °C, 1.00×10−14, is identical to its acid ionization constant, Ka. Nevertheless, several articles have been published erroneously purporting to give theoretical proof that the Ka of water is 10−15.743 (1.81×10−16) and that the Ka of the aqueous proton (hydronium ion) is 55.3 rather than 1.00. Here we argue that using the incorrect numbers has pedagogical implications beyond those of a simple error. Arguments for the incorrect Ka and pKa values require a misapplication of Henry's law and violate long‐standing methods that use Raoult's law and the conservation of matter to describe the behavior of solutions. As a result, chemistry students may be asked to accept one set of physical principles in one course and another set in another course. Here we argue for adherence to fundamental physical laws governing solution equilibria as applied to the autoprotolysis of water and all aqueous acid base equilibria.

Decompression sickness of medical personnel of a hyperbaric centre: A report of cases during 25 years of activity.

Medical hyperbaric sessions for Hyperbaric Oxygen Therapy, conducted at 2.4-2.5 ATA for 80 to 120 minutes, expose staff to increased risk of DCS due to the inhalation of compressed air, which increases gas solubility in body fluids as per Henry's Law. This study evaluates the incidence and risk factors of decompression sickness (DCS) among medical personnel in a hyperbaric centre over a 25-year period. Decompression sickness, characterized by gas bubble formation in tissues during planned decompression, was documented in 6 cases among 41,507 sessions. Symptoms varied from mild cutaneous to severe neurological manifestations, dependent on bubble size and location. Risk factors identified include age, physical condition, dehydration, and BMI. Preventative measures included adherence to decompression protocols, hydration, oxygen pre-breathing, and physical fitness maintenance. Despite these precautions, the occurrence of DCS underscores the inherent occupational risk faced by hyperbaric medical staff. The study advocates for stringent safety protocols and continuous monitoring to mitigate this risk.

Simulation of lithium hydroxide decomposition using deep potential molecular dynamics.

Chemical reactions and vapor-liquid equilibria for molten lithium hydroxide (LiOH) were studied using molecular dynamics simulations and a deep potential (DP) model. The neural network for the model was trained on quantum density functional theory data for a range of conditions. The DP model allows simulations over timescales of hundreds of ns, which provide equilibrium compositions for the systems of interest. Single-phase NPT simulations of the liquid show the decomposition of LiOH into lithium oxide (Li2O) and dissolved water (H2O). These DP results were validated by direct abinitio molecular dynamics simulations that confirmed the accuracy of the model with respect to reaction kinetics and equilibrium properties of the melt. The reactive vapor-liquid behavior of this system was subsequently studied using direct coexistence interfacial DP simulations. Partial pressures of H2O in the vapor are found to be in close agreement with available experimental measurements. By fitting temperature-dependent expressions for the reaction equilibrium and Henry's law constants, the equilibrium composition for any given initial composition and temperature can be quantitatively modeled. For high initial concentrations of Li2O or H2O, mixtures of LiOH + Li2O/H2O are found to undergo phase separation. The present study illustrates how DP-based molecular dynamics simulations can be used for quantitative modeling of multiphase reactive behavior with the accuracy of the underlying abinitio quantum chemical methods.

Prediction of organic sulfur solubility in mixed solvent using feature-based transfer learning and a hybrid Henry's law constant calculation method

Prediction of organic sulfur solubility in mixed solvent using feature-based transfer learning and a hybrid Henry's law constant calculation method

Interactions between volatile air pollutants and atmospheric water production – Effects of chemical properties, mechanisms, and transfer processes

Regional water scarcity is among the most urgent challenges of global climate change. Atmospheric water harvesting is a promising method to mitigate these challenges, and the atmospheric water generator (AWG) is already an established technology. Although this method can produce over 10,000L of water per day, the water's quality has not been studied in depth. Air pollutants, especially volatile organic compounds (VOCs), are potential contaminants of water produced from air. We evaluated the chemical and physical parameters of different VOCs that might influence their ability to be transferred from air to AWG water. Our findings strongly suggest that the ability to form hydrogen bonds is a key factor in this transfer. Henry's law constant, polarity, and intrinsic solubility were the main predictors of a VOC's transfer to AWG water. Hence, aliphatic or aromatic compounds (such as benzene or octane) were not found at significant concentrations in AWG water (e.g. above WHO guidelines), whereas ammonia and alcohol compounds were. This should be taken into consideration when analyzing potential contaminants in harvested atmospheric water. The condensation process itself was also found to enhance the transfer of VOCs into water droplets, and higher relative humidity (%RH) also increased VOC transfer. Gas-phase infrared spectrum analysis of VOCs at different %RH revealed possible interactions between water vapor and specific VOCs in the air. However, our main conclusion from this study is that VOC transfer from the air into AWG water occurs predominantly via dissolution in the condensed droplets, and strongly depends on their chemical properties of polarity and hydrogen-bond formation.

Experimental study of hydrogen sulfide (H2S) behavior in brine/n-decane mixtures under HPHT conditions

This research investigates the dynamic behavior of hydrogen sulfide (H2S) under oil reservoir conditions, focusing on their interplay within both aqueous and organic phases. Surprising findings emerge, notably the heightened solubility of H2S at 250°C compared to 150°C, with values of 19.9 mg to 41.5 and 12.8 mg to 16.4 mg in 100ml of solution, respectively, diverging from conventional expectations, due to organosulfur compounds generated at the water/n-decane interface under high pressure and temperature conditions. Through an examination of Henry's Law and the calculation of Henry's constants across several temperatures, insights into these observations are gained. In the organic phase, temperature is observed to catalyze the formation of organosulfur compounds from n-decane and H2S. Notable compounds identified include aromatic hydrocarbons bearing sulfur substituents. highlighting the presence of 2-Propyldibenzothiophene (2 – 392 mg/mL), which represents between 57 and 95% of the total concentration of organosulfur compounds found in the organic fraction, being more abundant at 250°C. These findings underscore the intricate interplay between temperature, pressure, and phase composition, elucidating the nuanced solubility patterns and reaction dynamics of sulfur and organosulfur compounds.

Selectivities of Carbon Dioxide over Ethane in Three Methylimidazolium-Based Ionic Liquids: Experimental Data and Modeling.

This work focused on the solubility of ethane in three promising ionic liquids {1-Hexyl-3-methylimidazolium bis(trifluormethylsulfonyl) imide [HMIM][Tf2N], 1-Butyl-3-methyl-imidazolium dimethyl-phosphate [BMIM][DMP], and 1-Propyl-3-methylimidazolium bis(trifluoromethyl-sulfonyl)-imide [PMIM][Tf2N]}. The solubilities were measured at 303.15 K to 343.15 K and pressures up to 1.4 MPa using a gravimetric microbalance. The overall ranking of ethane solubility in the ionic liquids from highest to lowest is the following: [HMIM][Tf2N] > [PMIM][Tf2N] > [BMIM][DMP]. The Peng-Robinson equation of state was used to model the experimental data using three different mixing rules: van der Waals one, van der Waals two, and Wong-Sandler mixing rules combined with the Non-Random Two-Liquid model. The average absolute deviations for the three mixing rules for the ionic liquids at the three temperatures were 4.39, 2.45, and 2.45%, respectively. Henry's Law constants for ethane in [BMIM] [DMP] were the highest (lowest solubility) amongst other ionic liquids studied in this work. The solubility ranking for the 3 ILs was confirmed by calculating their overall polarity parameter (N) using COSMO-RS. The selectivity of CO2 over C2H6 was estimated at three temperatures, and the overall ranking of the selectivity was in the following order: [PMIM][Tf2N] > [BMIM][DMP] > [HMIM][Tf2N] > Selexol. Selexol is an efficient and widely used physical solvent in gas sweetening. It has lower selectivity than the three ionic liquids studied. [PMIM][Tf2N], a promising solvent, has the highest selectivity among the three ILs studied and would, therefore, be the best choice if, in addition to carbon dioxide capture, ethane co-absorption was to be avoided. The enthalpy and entropy of solvation at infinite dilution were also estimated.

Insights on influence of polymer molecular weight on gas sorption, transport and plasticization in glassy 6FDA-DAM polyimide membranes

Insights on influence of polymer molecular weight on gas sorption, transport and plasticization in glassy 6FDA-DAM polyimide membranes

Oil sands process-affected water composition effect on Henry's law constants for polycyclic aromatic compounds: Theory and experiment

Oil sands process-affected water (OSPW) is a source of atmospheric emission for polycyclic aromatic compounds (PACs), compounds known to have toxic effects on humans. Estimating emissions and assessing the chemical fate of PACs requires measured or predicted physical-chemical properties such as Henry's law constants (H), that can be used to predict chemical transfer into the atmosphere. OSPW is a complex water-based mixture that is highly variable in composition and nature and contains both organic and inorganic ions. This study uses COSMO-RS solvation theory to estimate and compare Henry's law constants for a set of PACs in both water and theoretically modelled OSPW, to assess the expected deviation that occurs from pure water H values due to the ionic content within OSPW. Experimental measurements of Henry's law constants for PACs in pure water and OSPW using EVA-coated passive dosing and sampler beads were also made in support of our theoretical predictions. For the theory work, OSPW composition data for the Athabasca oil sands in Alberta were used to model a simulated OSPW environment with realistic sodium, chloride, fluoride, sulfate, potassium, bicarbonate, and naphthenic acid concentrations. Theory results indicate that the combined presence of these ions at OSPW concentrations has a negligible effect on H values, causing on average a 3% or 0.014 log unit deviation. By comparison, temperature has a much larger influence on H values, with estimations showing an average 0.20 log unit increase for a 5°C increase in temperature. The experimental results demonstrate that Henry's law constants can be accurately and precisely measured with this technique in pure water but with less precision in OSPW. Nevertheless, the experimental results support the conclusion that Henry's law constants for OSPW can be accurately estimated assuming a pure water phase.

Urban air PCDD/Fs: Dry deposition fluxes and mass transfer coefficients determined using a water surface sampler

Polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) cause significant environmental concerns. Atmospheric PCDD/Fs permeate water bodies and other ecosystems through wet and dry deposition. In an urban site, dry deposition flux samples of gaseous phase PCDD/Fs were collected by a water surface sampler (WSS) operated between June 2022 and June 2023. There is a conspicuous absence of literature on the direct measurement of dry deposition flux levels in the gaseous phase of PCDD/Fs. In the study, PCDD/Fs in the gas phase reaching the WSS dissolved in the water according to Henry's Law. The PCDD/Fs in the water were transferred to an XAD-2 resin column, sorbing the dissolved PCDD/Fs. The average monthly gas phase dry deposition flux was 34.07±9.35pg/m2-day (7.35±2.16pg I-TEQ/m2-day). The highest flux was measured in March (49.53pg/m2-day), and the lowest was in August (18.64pg/m2-day). These values indicated the direct flux from air to water. The atmospheric concentration of the gas-phase ranged from 68.38 to 126.88fg/m3 (13.22-25.01fg I-TEQ/m3). Dry deposition fluxes and concentrations of atmospheric PCDD/Fs were bigger in the colder months than in the warmer months. This was probably due to a significant increase in residential heating during the colder months, decreased photochemical reactions, and lower mixing heights. Regarding congeners in the dry deposition flux and concentration values in I-TEQ units, 2,3,7,8-TCDD compound predominated with the proportions of 31.61±7.76% and 29.09±12.34%, respectively. Concurrently measured dry deposition flux (Fg) and ambient air concentration (Cg) of PCDD/Fs were considered in the determination of mass transfer coefficient (MTC = Fg/Cg) calculation for each PCDD/F congener. The average MTC for targeted 17 PCDD/Fs was 0.45±0.15cm/s, and it fluctuated between 0.89±0.30cm/s for 2,3,7,8-TCDF and 0.2±0.16cm/s for OCDD.

Evaluation of the vacuum effect on headspace solid-phase microextraction of volatile organic compounds from aqueous samples using finite element analysis modeling

Evaluation of the vacuum effect on headspace solid-phase microextraction of volatile organic compounds from aqueous samples using finite element analysis modeling