Henry's Law Coefficient Research Articles

Solubility of acetone in low‐temperature (210–240 K) sulfuric acid solutions

The solubility of acetone in low‐temperature sulfuric acid solutions was studied in a low‐pressure Knudsen cell reactor. The time dependence of the uptake coefficient was analyzed to give effective Henry's law coefficients for acetone in 48–68 wt % sulfuric acid solutions between 210 and 240 K. The measured solubilities suggest that very little acetone will be partitioned into sulfate aerosol particles in the upper troposphere. Addition of ammonium sulfate to the sulfuric acid reduced the solubility slightly. No evidence was observed for reaction of dissolved acetone with itself or with nitric acid under the conditions of these experiments.

Temporal and Longitudinal Characteristics of Volatile Organic Compound Emissions from Aeration Units of Publicly Owned Treatment Works

ABSTRACT The temporal and longitudinal characteristics of volatile organic compound (VOC) emissions from the aeration units of a publicly owned treatment works (POTWs) have been investigated by systematic monitoring and mathematical modeling. Field tests have been conducted at a 120-mgd wastewater treatment plant to investigate the hourly, weekly, and seasonal changes of VOC emissions. Variations of VOC emissions along the length of the aeration units have been tested and modeled. Most VOCs have decreasing concentration profiles. Henry's law coefficients and biodegradation constants for the detected compounds have been validated with the improved models and the field test data. More than one-half of the emissions were found to have been generated from the first one-third of the aeration unit length.

A method of validation and parameter evaluation for dual-mode sorption model

A method of visual validation of a widely used dual-mode model for sorption of gases in glassy polymers is presented. Instead of directly fitting the model equation to the sorption data to determine its three parameters, the method evaluates one of the parameters, Henry's law coefficient independently and then plot the data in a linear way. Good linearity was obtained from such plots for the sorption data of CO 2 in polycarbonate and polysulfone, which indicated the validity of the assumed model. Moreover, parameter values determined accordingly were seen to be reasonable and self-consistent. Applications of the method were also illustrated for detecting deviations from the dual-mode sorption. Finally, a normalized linear plot is discussed by which sorption isotherms obeying the dual-mode model could be transformed to parallel lines and be specified by a dimensionless parameter.

Determination of Henry's law coefficients by combination of the equilibrium partitioning in closed systems and solid-phase microextraction techniques

This paper describes the determination of Henry's law coefficients by means of the EPICS (equilibrium partitioning in closed systems) technique in combination with SPME (solid-phase microextraction). The use of solid-phase microextraction-sampling allowed us to extend the possibilities of the equilibrium partitioning in closed systems technique with respect to the range of Henry's law coefficients which can be measured. Whereas the equilibrium partitioning in closed systems technique is limited to determine air–water equilibrium partitioning of volatile compounds with Henry's law coefficients of at least 0.06 (dimensionless), the current method allowed to measure coefficients between 0.0023 and 13.5. In this way Henry's law coefficients of 20 compounds, being in a range covering five orders of magnitude, were measured with relative standard deviations between 1.0 and 19.8% (mean standard deviation: 5.7%; median of standard deviations: 4.8%, n=99). Several types of compounds were examined i.e. aliphatic hydrocarbons, monocyclic and polycyclic aromatic hydrocarbons, chlorinated and fluorinated compounds, ethers and esters, biphenyl and N-containing compounds, including compounds for which availability of experimental Henry's law coefficients is limited. Measurement of the equilibrium partitioning in the 2 to 25°C range allowed to establish relations of Henry's law coefficient as a function of temperature.

Measurements of the Henry's Law Coefficients of 2-Methyl-3-buten-2-ol, Methacrolein, and Methylvinyl Ketone

Using an equilibrium headspace technique, Henry's law coefficients were measured for methacrolein (H = 6.5 ± 0.7 M atm-1) and methylvinyl ketone (41 ± 7.0 M atm-1) in water at 25 °C. In addition, 2-methyl-3-buten-2-ol was studied at 30 °C in water and in an aqueous ionic solution representative of plant tissue. Similar values were found in deionized water (65 ± 3.5 M atm-1) and in a 0.05 mol kg-1 Ca2+, K+, NO3-, SO42- solution (62 ± 0.8 M atm-1). These Henry's Law coefficients are too small to allow for significant partitioning of methacrolein, methylvinyl ketone or methylbutenol into cloud water under equilibrium conditions.

Modeling Oxidizing Scrubbers for Odor Control

In an oxidizing scrubber for odor control, the odorant is absorbed in a scrubber and must be oxidized to allow steady-state operation. The rate of absorption depends on the Henry's law coefficient, the gas- and liquid-phase mass transfer coefficients, and the rate of the oxidation reaction. The effect of a liquid-phase reaction on the liquid-phase mass transfer is often expressed in terms of an enhancement factor. Pseudo-first-order reaction rates were estimated for chlorination reactions for selected odorants. For simple amines and ammonia, the pseudo-first-order reaction rate is very fast, resulting in high enhancement factors for typical values of the mass transfer coefficients and odorant liquid-phase diffusion coefficients. For phenol and toluene, the reaction rate is relatively slow, and the enhancement factor is very close to unity.

Measurements of Henry's law constant for hydrogen in water utilizing a palladium differential resistance sensor

AbstractA differential‐resistance hydrogen sensor utilizing palladium, has been used for determining Henry's Law coefficient for hydrogen in water. This method does not necessitate equilibration of the gas and liquid phases. In the temperature range 187°C < T < 306°C, Henry's Law coefficient so determined is about 16 to 22% lower than the value determined from equilibration experiments.

Characterization of Volatile Organic Emissions and Wastes from a Swine Production Facility

AbstractAnalytical methods for monitoring the volatile organic compound (VOC) emissions, for defining atmospheric transport coefficients, and for monitoring solution phase chemistry have been developed to define processes regulating emission of malodorous and other VOCs from a high odor swine production facility. Of the 40 organic compounds identified in liquid and outdoor air samples from the swine production facility, 27 VOCs were confirmed to contribute to decreased air quality in the vicinity of the facility. Specifically, C2 through C9 organic acids demonstrated the greatest potential for decreased air quality, since these compounds exhibited the highest transport coefficients and highest airborne concentrations. Flux measurements suggested that the total rate of nonmethane VOC emissions from the deep basin swine waste storage system was 500‐ to 5700‐fold greater than established nonmethane VOC fluxes from nonanthropogenic sources. The volatilization rate of malodorous and other VOCs from the stored swine waste was positively correlated with wind velocity between 0.2 and 9.4 m s−1, and a maximum concentration of VOCs present in the air was observed to occur at a wind velocity of 3.6 m s−1. Experimental Henry's law coefficients adequately predicted the transport efficiency observed for some of the VOC emissions measured from air samples taken at 0, 25, and 100 m from the swine waste storage basin; however, results indicated that laboratory‐based extraction procedures, currently used to estimate malodor potential for swine slurry samples, provide an inaccurate representation of malodorous and other airborne VOCs actually present in the air near swine production facilities.

The effect of hydrogen bonding on vapor diffusion in water-soluble polymers

Water-vapor transport in poly(acrylic acid) (PAA), poly(N-vinyl-2-pyrrolidone) (PVPo), and their 2 : 1 interpolymer complex was measured between 30 and 50°C. It was found that the formation of interpolymer hydrogen bonding not only caused the Tg of the complex to be higher than those of the individual components, but also affected vapor-sorption behaviors. In the high vapor pressure region (Pr > 0.5), sorption isotherms in pure PAA and PVPo follow the Flory–Huggins solution theory and the sorbed water molecules may form clusters around the COOH groups in PAA and C=O groups in PVPo. However, sorption in the complex is almost linear for the entire range of water activities. The binary polymer—polymer interaction parameter between PAA and PVPo in the complex, ξPAA–PVPo, is less than zero, which is indicative of favorable interaction between PAA and PVPo. At lower water activities, sorption behaviors for water in the three polymers can be approximated by Henry's law and vapor-diffusion coefficients can be ranked as PVPo > complex > PAA. The water vapor diffusion coefficients in each system decrease with increasing Pr, in the region of Pr > 0.5 because the proportion of immobilized water molecules increases with vapor concentration. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 66: 279–291, 1997

Horizontal Bubble Train Apparatus for Heterogeneous Chemistry Studies: Uptake of Gas-Phase Formaldehyde

A new horizontal bubble train apparatus has been built to conduct time-resolved gas−liquid interaction studies of interest in atmospheric chemistry. In the apparatus, liquid is pumped horizontally through a 0.4 cm i.d. quartz tube at a controlled speed of 15−35 cm/s. A low-pressure (about 50 Torr) gas flow, carrying the trace gas of interest diluted in helium carrier gas, is injected through a moveable injector into the liquid flow forming well-defined bubbles that fill the diameter of the tube. In a controlled way, 10−25 bubbles are formed per second. The outlet gas flow is then sampled by a differentially pumped mass spectrometer. The position of the bubble injector, which is computer controlled by a stepping motor, determines the bubble travel distance and therefore the gas-liquid interaction time (typically 0.1−10 s). Modeling of the gas uptake and the validation of the apparatus performance are described. The apparatus can measure Henry's law coefficients (H) for non-reactive species in the range 10-...

Concentration polarization, separation factor, and Peclet number in membrane processes

Concentration polarization affects almost all the membrane separation processes and can be the cause of a substantial reduction in the separation factor and flux. A generalized equation relating the modified Peclet number to the concentration polarization occurring in the boundary layer is proposed and shown applicable to the majority of membrane separation processes like gas separations, reverse osmosis, ultrafiltration, pervaporation, and dissolved gas permeation in liquid. The membrane permeability, separation factor (or solute rejection), membrane thickness, boundary layer mass transfer coefficient, and Henry's law coefficient are the factors that determine the extent of polarization. An analysis is presented to offer a clean division of the hydrodynamic effect from the pure membrane property for membrane separation processes of liquid phases. Also the effect of membrane thickness on polarization is discussed. An attempt has been made to reconcile the different approaches taken for different membrane processes in the literature. Experimental data from widely different sources illustrate and confirm the present theory for pervaporative separation of dilute solutions of volatile organic compounds, dissolved gas permeation, and ultrafiltration of proteins and carbowax. Specific suggestions are made to obtain independent experimental measurements of the Peclet number and polarization index in terms of measurable quantities like the actual and intrinsic separation factors.

A Multi-Parameter Sensitivity Analysis of a Model Describing the Fate of Volatile Organic Compounds in Trickling Filters

ABSTRACT A frequency array technique was employed to assess the impact of process operating and design conditions, biofilm, and compound-specific properties on the fate of volatile organic compounds (VOCs) in trickling filter processes. The objective of the study was to identify the ranges of parameters over which model predictions of biodégradation, volatilization, and overall removal are particularly sensitive. The model was found to be most sensitive to liquid loading rates less than 20 m3/m2-d and gas loading rates less than 200 m3/m2-d. The model predictions indicate that an effective method for controlling VOC emissions is through control of trickling filter ventilation rates. Effluent recycle had only marginal impact on model predictions. Model predictions were most sensitive to biofilm thickness less than 1 x 10-4 m, liquid-gas mass transfer coefficients less than 0.10 m/d, Henry's law coefficients less than 0.10, and biodégradation rate coefficients less than 20 m3/kg-d. When employing the model for predictive purposes, greater care should be taken in defining parameters for compounds that lie within these ranges.

Water Analysis by Solid Phase Microextraction Based on Physical Chemical Properties of the Coating

A novel and simple method using solid phase microextraction (SPME) with poly(dimethylsiloxane) fiber coating and linear temperature-programmed retention index (LTPRI) has been developed to quantify petroleum hydrocarbons in water. Partition coefficients (K(fw)) for the analytes in water and SPME were established for a series of aromatics, cycloalkanes and alkanes. There is a linear relationship between log K(fw) for each hydrocarbon series and LTPRI. The slope of the curves for all the series are the same and related to the partial free energy of solution for the hydrocarbon-fiber coating solution. The y-intercept of the plots is distinct for each group of hydrocarbons and related to Henry's law coefficients for each series. Therefore, the K(fw) for a series of hydrocarbons can be estimated using literature Henry's law coefficients. This method was used to quantify BTEX-contaminated water.

Thermodynamic interactions in rubbery polymer/gas systems

The Flory–Huggins interaction parameters χ for 23 gases (He, Ne, Ar, Kr, Xe, H2, N2, O2, N2O, CO2, CH4, C2H4, C2H6, C3H6, C3H8, 1,3-C4H6, four C4H8's, n-C4H10, iso-C4H10, and n-C5H12) in five rubbery polymers (1,2-polybutadiene (PB), poly(ethylene-co-vinyl acetate)) (EVAc), polyethylene (PE), polypropylene (PP), and poly(dimethyl siloxane) (PDMS) were determined from either literature data on Henry's law coefficient and partial molar volume or those on sorptive dilation for each polymer/gas system. Values of χ for the gases increased in the order of PDMS < PP ≡ PB < EVAc ≡ PE. Among the gases except He and H2 whose χ values are not reliable, Ne and Xe have respectively the highest and the lowest values of χ for the polyolefins. The χ values of the hydrocarbons were compared together with previously reported χ values of n-alkanes C3-C10. The dependencies of χ upon concentration and temperature were discussed on the basis of the literature data. © 1997 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 35: 1049–1053, 1997

Oxygen uptake and VOC emissions at enclosed sewer drop structures

Municipal wastewater is currently receiving regulatory scrutiny as an emissions source for volatile organic compounds (VOCs). In response, the fate of VOCs at drop structures has been studied. The study described herein involved two major components. First, 64 pilot experiments were conducted to study the effects of drop height, liquid flow rate, and tail water depth on oxygen transfer. Second, 15 additional experiments were completed to determine the effects of the same parameters on the stripping of a cocktail comprising 10 volatile tracers. Headspace ventilation rates, chemical properties, and the differences between clean water and raw wastewater on VOC stripping were studied. Results suggest that oxygen is a useful surrogate for VOC measurements as both oxygen and VOC mass transfer were observed to be highly dependent on drop height and less on liquid flow rate. Stripping efficiencies for VOCs were observed to vary between 0.5 and 32% depending upon specific compounds and experimental conditions. VOC stripping was also observed to be greater from clean water as compared to wastewater. Gas‐liquid mass transfer of VOCs was seen to be a strong function of Henry's law coefficient, suggesting the Occurrence of gas‐phase mass transfer resistance.

Uptake of NO3 on Water Solutions: Rate Coefficients for Reactions of NO3 with Cloud Water Constituents

The reactive uptake coefficients, γ, of NO3 onto aqueous solutions containing ions X- = HSO3-, SO32-, HCOO-, CH3COO-, and OH- were measured at 273 ± 1 K using a wetted-wall flow tube reactor. The values of H2D&#x1d4c1; k (H = Henry's law coefficient, D&#x1d4c1; = diffusion coefficient in the liquid phase, and k = second-order rate coefficient for the liquid phase reactions of NO3 with X-) for the reactive uptake of NO3 were determined by measuring γ as a function of liquid phase reactant concentration. The linear correlation between the measured rate coefficients and those for corresponding SO4- reactions, and the dependence of the measured rate coefficients on the redox potential of the X/X- pair suggest that the NO3 + X- reactions proceed by electron transfer. The atmospheric implications of these findings are briefly discussed.

Predicting Oxygen Uptake and VOC Emissions at Enclosed Drop Structures

Drop structures used during wastewater collection and treatment are sources for volatile organic compound (VOC) emissions. To assist in the reduction of such emissions, pilot-scale experiments were completed using municipal wastewater to study the effects of drop height, liquid flow rate, and tailwater depth on oxygen transfer, and to evaluate the effects of the same parameters on the stripping of 10 VOC tracers. Results were used to develop predictive models for oxygen and VOC transfer. Oxygen uptake at the pilot drop structure suggests that the drop height is the most important parameter influencing oxygen uptake at enclosed drop structures. Tailwater depth had little effect on oxygen transfer at the drop structure. Stripping of VOCs at drop structures was seen to be a strong function of Henry's law coefficient. This sensitivity was related to gas-phase resistance in mass-transfer and/or VOC accumulation in the air bubbles. Incorporating gas-phase resistance and an appropriate a factor for wastewater into the model allowed the prediction of VOC deficit ratios and estimation of VOC stripping at drop structures for both clean water and wastewater.

Henry's Law Constants and Distribution Coefficients of Sulfur Hexafluoride in Water from 25 °C to 230 °C

The solubility of SF6 in water has been measured between 75 °C and 230 °C by direct sampling of SF6-saturated water contained in a stainless steel autoclave. The solubility (reported as a distribution coefficient) ranges from ln B = 13.93 at 75 °C to ln B = 8.34 at 230 °C. The experimental data were combined with low-temperature data from the literature to obtain an empirical equation for the Henry's law coefficient over the temperature interval 25 °C to 230 °C. At temperatures above about 210 °C an unexpectedly rapid decrease in SF6 gas partial pressure occurred, and above this temperature deviation from Henry's law also was observed.

Modelling VOC emissions at wastewater drop structures

AbstractA mechanistic model was developed to predict VOC emissions at drop structures. The mass transfer mechanisms that have been incorporated into the model include the falling film (disintegrating jet), turbulent mixing in the area of jet impact, and bubbles in the tailwater resulting from air entrainment. Air entrainment appears to be the most significant mechanism affecting VOC emissions, following by the falling film. A sensitivity analysis was also performed using parameter values that are considered “typical” for wastewater drop structures and operating conditions. The largest variation in stripping was associated with air entrainment, liquid and air flow, Henry's law coefficient and degree of equilibrium for entrained bubbles.

A field scale evaluation of the airstripping of volatile organic compounds by surface aerators

The stripping of volatile organic compounds (VOCs) by surface aerators was evaluated in experiments performed at field scale. Each experiment consisted of dosing a tank containing tapwater with a selection of VOCs, activation of the aerator, and subsequent monitoring of the disappearance of the compounds. The tank contents were deoxygenated before the experiment thereby allowing concurrent measurement of the uptake of oxygen. Experiments were performed with two aerators with differing power inputs and aeration patterns and over a range of temperatures from 3 to 22°C. Overall mass transfer coefficients were calculated for each compound in each experiment. The impacts of temperature and aerator horsepower on the mass transfer coefficients of the candidate compounds were examined and relationships were calibrated with the experimental data. The fundamental gas and liquid mass transfer coefficients were calibrated and the ratio of gas to liquid phase mass transfer coefficient was estimated to range from 16 to 24. The estimated ratio of kg/kl was found to be relatively insensitive to variations in the Henry's Law coefficient over the range typically observed in the literature. The observed ratio was lower than that previously reported in the literature and would suggest a greater impact of gas phase resistance than previously thought. The lower value of the ratio may be attributed to mass transfer limitations caused by entrained air.