Permeability Coefficient Values Research Articles

Effect of current density, concentration of ternary electrolyte and type of cations on the monovalent ion selectivity of surface-sulfonated graft anion-exchange membranes: modelling and experiment

The dependence of monovalent-ion selectivity of surface-sulfonated anion exchange membranes (s-AEMs) on the electrodialysis (ED) desalination current density, the concentration of equimolar ternary electrolyte (XCl + X2SO4) in the total concentration range 0.04–0.2 M, and the type of cations (X = H, Cs, Na) has been studied. The membrane current-voltage characteristics and values of the diffusion permeability coefficients in electrolyte solutions and their mixtures were measured. It was shown that Cl/SO4-selectivity coefficients (PCl|SO4) increase along with current density, reaching maximum values at the limiting current density (Ilim). The PCl|SO4 maximum value of 5.5 was achieved for the s-AEM-18 membrane in the ED-desalination of equimolar ternary electrolytes NaCl/Na2SO4, and CsCl/Cs2SO4 (total salt concentration 0.04 M) at 1.4 and 2.4 mA cm−2 current densities, respectively. At the overlimiting currents, the splitting of water and the decrease of Cl/SO4-selectivity were observed. The obtained experimental results are interpreted using simplified mass transfer and numerical simulations in the framework of Nernst-Planck-Poisson equations implemented in the COMSOL® Multiphysics software. The model represents the modified membrane as an asymmetric bipolar membrane with two diffusion boundary layers (DBL) in electrolyte solutions on both sides of the membrane interface. The model includes the water splitting at the bipolar boundary and the chemical equilibrium between sulfate and hydrogen sulfate ions. The numerical simulations qualitatively predict the behaviour of s-AEMs membranes when the abovementioned conditions change.

Percutaneous penetration and dermal exposure risk assessment of chlorinated paraffins

The widespread occurrence of chlorinated paraffins (CPs) in environmental matrices has resulted in a high frequency exposure to CPs via dermal contact. To quantitatively estimate percutaneous penetration of CPs, Episkin® human skin equivalents (HSE) was applied as an in vitro model to evaluate the mechanism of percutaneous penetration of CPs. The co-exposure of CPs mixtures to HSE showed that about 11.7% and 10.2% of short-chain CPs (SCCPs) and medium-chain CPs (MCCPs) could penetrate the HSE and enter the receptor fluid, while no long-chain CPs (LCCPs) (C>17) were able to penetrate the HSE during the 36-h assay period. The experimentally obtained permeability coefficient (Kp) values for CPs were significantly (p < 0.01) negatively correlated with their log octanol–water partition coefficient (log Kow). Furthermore, 24 participants were recruited to assess direct human dermal exposure to CPs in China with the total CPs collected onto hand wipes and forehead wipes being 96,600 and 30,400 ng/person, respectively. The proportion of total SCCPs and MCCPs intake via dermal penetration (skin area investigated in this study) accounting for 2.0% of the total intake of CPs. Considering the total skin surface of human body is around 20 times of the area studied, the total intake of CPs through dermal penetration could be a significant exposure pathway.

Organophosphorus Polyurethane Ionomers as Water Vapor Permeable and Pervaporation Membranes.

Organophosphorus polyurethane ionomers (AEPA-PU) based on aminoethers of ortho-phosphoric acid (AEPA) were obtained and studied as pervaporation membrane materials for separating isopropanol/water mixtures. The regularities of the change in the water vapor permeability of AEPA-PU were also investigated. It has been established that an increase of solute content in the composition of the urethane-forming system and the content of ionogenic groups in AEPA leads to a noticeable increase in the vapor permeability of the resulting film materials. An increase in water vapor permeability values is accompanied by a significant increase in the pervaporation characteristics of AEPU-PU. It was shown that the conditions promoting clustering of phosphate anions cause an increase in the values of the vapor permeability coefficient of AEPA-PU obtained using polyoxypropylene glycol. However, the hydrophobicity of the polypropylene glycol surrounding the clusters makes it difficult for water to move through the polymer matrix. Due to the hydrophilicity of polyoxyethylene glycol, the highest values of water vapor permeability and pervaporation characteristics are achieved for AEPA-PU synthesized using PEG.

Performance of granular road base and sub-base layers containing recycled concrete aggregate in different ratios

ABSTRACT In this study, the usability and performance properties of recycled concrete aggregates (RCA) as granular road base (GRB) and granular road subbase (GRSB) material were investigated. A natural aggregate and the RCAs obtained from concretes with three different compressive strength and mixtures created by adding the RCAs to NA at the ratios of 25, 50 and 75% were used. Physical properties, modified Proctor, resilient modulus, permanent deformation, California bearing ratio (CBR), and permeability tests were carried out on all mixtures. Resilient modulus values (Mr) were obtained using three different resilient modulus models. The highest Mr value among pure RCAs was observed for RCA2 (average of 200 MPa). For the mixture samples, the highest Mr values were obtained in the mixtures containing RCA1 (average of 250 MPa). The minimum of permanent deformation value (ϵ p ) for the mixtures was obtained when the ratio of the RCA1 in the mixtures was 50% (ϵ p = 0.238%). The obtained CBR values were not related to the Mr values, and the highest CBR values were found for the pure RCAs (average of 126%). High permeability coefficient values (average of 9.973×10−6 m/s) were obtained for the RCAs. As a result, it was more appropriate to blend the RCAs with the natural material rather than to use them in pure form. In general, it was appropriate to use 50% of RCAs in the mixtures. It was observed that if concrete compressive strength is as high as in RCA1 (18.5 MPa), RCA can be used even in the mixture at a ratio of 75%.

Comparative study on the intestinal absorption of three gastrodin analogues via the glucose transport pathway

Gastrodin is the main active constituent of Tianma, a famous traditional Chinese herbal medicine. Our previous research has found that gastrodin is absorbed rapidly in the intestine by the sodium-dependent glucose transporter 1 (SGLT1). In the current report, gastrodin is the best glycoside compound absorbed via the glucose transport pathway. This study aimed to investigate the effect of the slight difference in chemical structure on the drug intestinal absorption via the glucose transport pathway. Traditional biopharmaceutical and computer-aided molecular docking methods were used to evaluate the intestinal absorption characteristics of three gastrodin analogues, namely, salicin, arbutin and 4-methoxyphenyl-β-D-glucoside (4-MG). The oil–water partition coefficient (logP) experiments showed that the logP values of the gastrodin analogues followed the order: 4-MG > salicin > arbutin. In vitro Caco-2 cell transport experiments demonstrated that the apparent permeability coefficient (Papp) value of arbutin was higher than those of salicin and 4-MG. In situ single-pass intestinal perfusion experiments showed that the absorption of arbutin and 4-MG was better than that of salicin and that the absorption of the three compounds in the colon was lower than that in the small intestine. Quantitative real-time polymerase chain reaction results confirmed that the SGLT1 mRNA expression in the small intestine of rats was obviously higher than that in the colon of rats. In vivo pharmacokinetic experiments demonstrated that the oral bioavailability of salicin was lower than those of arbutin and 4-MG. In vitro and in vivo experiments showed that glucose or phlorizin (SGLT1 inhibitor) could decrease the intestinal absorption of the three compounds. Contrary to the above biopharmaceutical experiments, the computer-aided molecular docking test showed that the affinity of salicin to the vSGLT receptor was stronger than those of arbutin and 4-MG. In conclusion, the SGLT1 can facilitate the intestinal absorption of salicin, arbutin and 4-MG, and the slight difference in chemical structure can affect absorption.

Transport Characteristics of Plasma Membranes of PK-15 Passaged Cells

The values of permeability coefficients to water molecules and cryoprotectants are demanded to select the optimal duration of exposure of cells in cryoprotective media at the stage of their preparation for cryopreservation, as well as to find optimal cooling and warming rates during the freeze-thawing of cell suspensions. The necessary numerical values of such cell parameters as the osmotically inactive volume α and the surface-area-to-volume ratio γ were obtained for the analytical evaluation of the permeability coefficients of the PK-15 cells’ plasma membranes using physico-mathematical modelling. The permeability coefficients kp of the plasma membranes of PK-15 cells to 1,2-PD, EG, DMSO and glycerol cryoprotectants molecules, as well as the filtration coefficients Lp to water molecules at temperatures of 25, 15 and 5°C were determined by approximating the experimental data of the change in relative volume of cells on exposure time in the studied solutions by theoretical curves calculated on the basis of physical and mathematical model of passive transport of water and permeable substances under the condition of their maximum coincidence. The value of the activation energy of the transmembrane transfer of molecules of these substances is calculated

Release of dipeptidyl peptidase IV inhibitory peptides from salmon (Salmosalar) skin collagen based on digestion–intestinal absorption invitro

SummaryInhibition of dipeptidyl peptidase IV (DPP‐IV) was considered to be a crucial target for type 2 diabetes, and food‐derived peptides were superior source of DPP‐IV inhibitory peptides. The purpose of this investigation was to identify inhibitory peptides from salmon skin collagen using simulated digestion combined with Caco‐2 cell monolayer membrane model. The analysis in silico showed that TKLPAVF and YLNF were potential inhibitory peptides. Determination of the inhibition activity showed that the IC50 values of TKLPVAF and YLNF were 242.10 ± 3.40 and 146.90 ± 4.40 µm, respectively. Molecular docking results showed that seven hydrogen bonds were formed between YLNF and key residues of DPP‐IV. YLNF may be considered a novel DPP‐IV inhibitory peptide. In addition, YLNF could be transported by Caco‐2 cell monolayer membrane in intact, and the apparent permeability coefficient value was (3.54 ± 0.34) × 10‐6 cm s−1 at 5 mm.

Development and evaluation of two-parameter linear free energy models for the prediction of human skin permeability coefficient of neutral organic chemicals

The experimental values of skin permeability coefficients, required for dermal exposure assessment, are not readily available for many chemicals. The existing estimation approaches are either less accurate or require many parameters that are not readily available. Furthermore, current estimation methods are not easy to apply to complex environmental mixtures. We present two models to estimate the skin permeability coefficients of neutral organic chemicals. The first model, referred to here as the 2-parameter partitioning model (PPM), exploits a linear free energy relationship (LFER) of skin permeability coefficient with a linear combination of partition coefficients for octanol–water and air–water systems. The second model is based on the retention time information of nonpolar analytes on comprehensive two-dimensional gas chromatography (GC × GC). The PPM successfully explained variability in the skin permeability data (n = 175) with R2 = 0.82 and root mean square error (RMSE) = 0.47 log unit. In comparison, the US-EPA’s model DERMWIN™ exhibited an RMSE of 0.78 log unit. The Zhang model—a 5-parameter LFER equation based on experimental Abraham solute descriptors (ASDs)—performed slightly better with an RMSE value of 0.44 log unit. However, the Zhang model is limited by the scarcity of experimental ASDs. The GC × GC model successfully explained the variance in skin permeability data of nonpolar chemicals (n = 79) with R2 = 0.90 and RMSE = 0.23 log unit. The PPM can easily be implemented in US-EPA’s Estimation Program Interface Suite (EPI Suite™). The GC × GC model can be applied to the complex mixtures of nonpolar chemicals.

Jet-installation noise reduction with flow-permeable materials

This paper investigates the application of flow-permeable materials as a solution for reducing jet-installation noise. Experiments are carried out with a flat plate placed in the near field of a single-stream subsonic jet. The flat plate is modular and the solid surface near the trailing edge can be replaced with different flow-permeable inserts, such as a metal foam and a perforated plate structure. The time-averaged jet flow field is characterized through planar PIV measurements at three different velocities (Ma=0.3,Ma=0.5 and Ma=0.8, where Ma is the acoustic Mach number), whereas the acoustic far-field is measured with a microphone arc-array. Acoustic measurements confirm that installation effects cause significant noise increase, up to 17 dB for the lowest jet velocity, particularly at low and mid frequencies (i.e. St<0.7, with the Strouhal number based on the jet diameter and velocity), and mostly in the upstream direction of the jet. By replacing the solid trailing edge with the metal foam, noise abatement of up to 9 dB is achieved at the spectral peak for Ma=0.3 and a polar angle θ=40∘, with an overall reduction in the entire frequency range where jet-installation noise is dominant. The perforated plate provides lower noise reduction than the metal foam (7 dB at the spectral peak for Ma=0.3 and θ=40∘), and it is less effective at low frequencies. This is related to the values of permeability and form coefficient of the materials, which are the major parameters controlling the pressure balance across the trailing edge and, consequently, the noise generated by the plate. However, despite having a high permeability, the plate with the metal-foam trailing edge still has a distinct noise production at mid frequencies (St≈0.43 for Ma=0.3). Based on the analyses of different treated surface lengths, it is conjectured that the solid-permeable junction in the plate acts as a new scattering region, and thus its position also affects the far-field noise, which is in line with analytical predictions in the literature. Nonetheless, both types of inserts provide significant noise reduction and are potential solutions for the problem of jet-installation noise.

Development a multicellular model to investigate the intestinal-vascular transport barrier of drug

Multicellular transport models for drug have received more attention and research due to a closer physiological structure. A Caco-2/EA.hy926 cell co-culture model was constructed to simulate intestinal-vascular barrier. The morphology of microvilli-like and desmosomes structure indicated the tight connection of Caco-2 cells. The apparent permeability coefficient value of phenol red (≤1 × 10−6 cm/s), trans-epithellal electric resistance value (≥300 Ω cm2) and the alkaline phosphatase activity ratio of AP to BL side presented a confluent and integral cell monolayer with well-established differentiation. The microscopic images and vascular endothelial cadherin expression demonstrated the adhesion junction between EA.hy926 cells. The constructed multicellular model differentiated drug transport behavior. The transport potential of EA.hy926 and Caco-2 cells was similar for daidzein and different for daidzin. Combined with multiple evaluation indexes, it could track the multicellular transport process of nanoparticles. The new multicellular model exhibited more in vivo-like characteristics and architecture from intestine to blood, and a potential improvement of in vitro absorption and transport models for drug.

On the issue of scientific substantiation of the method for forecasting the hazardous properties of coal seams

The study of filtration permeability of the barrier pillar between the isolated fire section and the worked longwall ventilation drift was completed using the mathematical model developed by the authors for coupled processes of rock deformation and gas filtration. The problem is solved involving a finite element method implemented in the author's programme. When solving, the parameters of width of the barrier pillar and thickness of the mined coal seam were varied. The article presents the results of calculating the values of geomechanical parameters, permeability coefficients and gas pressure in the filtration area. It is shown that with an increase in thickness of the coal seam, intensity of the crack formation process increases in the barrier pillar. With small pillar width, the coal seam along its entire length is in a disturbed state, as well as the rocks of its roof and soil. The filtration areas around the worked longwall ventilation drift and the isolated conveyor drift are connected both along the coal seam and along the host rocks. This means that at a certain value of the pressure drop, filtration of fire gases into the mine workings of the worked excavation section is possible. With a greater width of the pillar, between disturbed rocks around the mine workings of the worked section and isolated fire one, there is a barrier made of undisturbed rocks. That impermeable barrier prevents gas filtration from one mine workings to another. Its width decreases with an increase in the thickness of the coal seam. Based on the results of calculating gas pressure, it is shown that methane from the coal seam moves into atmosphere of the mine workings, where gas pressure has lower values. At the same time, for the accepted conditions, with a pillar width of 20 m and a seam thickness of 0.4 m, gas is filtered from the mine workings of isolated fire section into the adjacent excavation section along the disturbed rocks of the seam roof. In the rest of the cases, the areas of low pressure around the mine workings are separated by zones of higher pressure, exceeding pressure of fire gases in the isolated section. Filtration of fire gases into atmosphere of the worked excavation section is impossible under such conditions.

Analysis of the influence of heat source well parameters on pumping temperature of groundwater source heat pump

In this paper, MATLAB software is used to simulate the influence of parameters of different heat source wells on pumping temperature in groundwater source heat pump system. The absolute value of horizontal permeability coefficient of aquifer will not affect its pumping temperature, but when the permeability coefficient ratio increases from 1 to 10, the pumping temperature decreases by 1.1°C; When the specific heat capacity increases from 2000 kJ / m3 · °C to 3000 kJ / m3 · °C, the pumping temperature decreases by 0.8 °C; When the degree of thermal dispersion increases from 1m to 3m, the pumping temperature decreases by 0.4°C.

The influence of working seam thickness on permeability of barrier pillars near isolated fire sections

The study of filtration permeability of the barrier pillar between the isolated fire section and the worked longwall ventilation drift was completed using the mathematical model developed by the authors for coupled processes of rock deformation and gas filtration. The problem is solved involving a finite element method implemented in the author's programme. When solving, the parameters of width of the barrier pillar and thickness of the mined coal seam were varied. The article presents the results of calculating the values of geomechanical parameters, permeability coefficients and gas pressure in the filtration area. It is shown that with an increase in thickness of the coal seam, intensity of the crack formation process increases in the barrier pillar. With small pillar width, the coal seam along its entire length is in a disturbed state, as well as the rocks of its roof and soil. The filtration areas around the worked longwall ventilation drift and the isolated conveyor drift are connected both along the coal seam and along the host rocks. This means that at a certain value of the pressure drop, filtration of fire gases into the mine workings of the worked excavation section is possible. With a greater width of the pillar, between disturbed rocks around the mine workings of the worked section and isolated fire one, there is a barrier made of undisturbed rocks. That impermeable barrier prevents gas filtration from one mine workings to another. Its width decreases with an increase in the thickness of the coal seam. Based on the results of calculating gas pressure, it is shown that methane from the coal seam moves into atmosphere of the mine workings, where gas pressure has lower values. At the same time, for the accepted conditions, with a pillar width of 20 m and a seam thickness of 0.4 m, gas is filtered from the mine workings of isolated fire section into the adjacent excavation section along the disturbed rocks of the seam roof. In the rest of the cases, the areas of low pressure around the mine workings are separated by zones of higher pressure, exceeding pressure of fire gases in the isolated section. Filtration of fire gases into atmosphere of the worked excavation section is impossible under such conditions.

Research on Permeability Coefficient of Heterogeneous Geomaterials Based on Digital Images

According to the relationship between permeability and porosity of geotechnical materials, a finite element model representing pore and solid particles is generated randomly according to the porosity of a given finite element calculation model. According to Darcy’s law of flow distribution and steady seepage in the finite element random simulation section, the equivalent permeability coefficients at different porosities are calculated, and the relationship between the equivalent permeability coefficient and the porosity of rock and soil is studied. The results show that the equivalent permeability coefficient is proportional to the porosity with the same pore size. In order to study the seepage characteristics of structural planes of nonmaterial geotechnical materials in different strata contact zones, the formulas for calculating the deformation parameters and permeability coefficients of heterogeneous rock masses with single nonmaterial geotechnical materials are deduced theoretically, and the correctness and applicability of the formulas are verified by experiments. The rock mass sample selected in this paper is granite, which is simulated and analyzed by sandstone in the experiment. The results show that the permeability coefficients of coarse sandstone, fine sandstone, and heterogeneous rock mass are different under the same water pressure and confining pressure. This shows that the lithology on both sides of the nonmaterial geotechnical material surface has a significant influence on the permeability of the nonmaterial geotechnical material rock mass; the permeability coefficient of the nonmaterial geotechnical material rock mass decreases with the increase of confining pressure, the numerical change is limited to a certain confining pressure range, and the permeability coefficient tends to be stable when the confining pressure reaches a certain value. Comparing the theoretical calculation value of permeability coefficient of rock mass with the experimental result, it is found that the two values are in good agreement, which indicates the correctness and applicability of the theoretical calculation formula of permeability coefficient of rock mass of single intangible geotechnical material.

Pore distribution and classification of loess

The micro-pore characteristics in undisturbed loess have a profound influence on the permeability characteristics. Based on the results of permeability test, it is proved that the permeability coefficient of soil samples with the same porosity ratio is different and the internal characteristics are diversified. The internal pores of undisturbed loess were studied by scanning electron microscopy (SEM). The results show that there are obvious differences in the internal microstructure of the original loess with the same porosity ratio. There are root holes in undisturbed loess, the number and size of which directly affect the value of permeability coefficient. With the increase of pore diameter, the pore size distribution changes gradually, and the influence of small pores is gradually weakened, while the influence of large pores is more obvious. Therefore, only the pore ratio parameter used in engineering can not completely describe the pore characteristics of soil, it is necessary to introduce other microscopic parameters to describe.

Metal industry waste desiccation behavior with the addition of bentonite as a landfill liner

The existence of garbage in the environment can cause pollution. Therefore, it is necessary to carry out waste management, one of which is by building a landfill. Landfill liner should have a permeability coefficient <10−6 cm/sec to prevent contamination. Currently, the affordable material used as landfill liner is clay, but it is quite rare. An alternative material we can use is metal industrial waste, which has not been utilized. Metal industrial waste has a permeability coefficient, namely 25.34560 x 10−6 cm/s. In order to reduce the permeability coefficient value, metal industrial waste is added with bentonite material, which has a low permeability value with variations of 0%, 5%, 10%, 15%, 20%, and 25% addition of bentonite. Digital image processing techniques are used to calculate crack intensity factor (CIF) values using the Matlab 2019 software. The results showed that the permeability value that fulfilled was the variation of 20% bentonite addition of 0.8059 x 10−6 cm/s and 25% of 0.5059 x 10−6 cm/s. While the CIF results showed that only the variation of 25% bentonite addition were not eligible because they had a crack area >4%. Thus it can be concluded that the best composite is metal industrial waste with 20% bentonite.

Utilization of Soybean as Catalyst Material in Enzyme-Mediated Calcite Precipitation (EMCP) for Crack Healing Concrete

This paper discussed the effect of soybean as the catalyst in the Enzyme-Mediated Calcite Precipitation (EMCP) method for crack healing concrete. The existence of cracks in the concrete will reduce the quality of the concrete, so it needs concrete repair efforts, one of which was by injection using the EMCP method. The EMCP technique employs the plant-derived urease enzyme catalyze the reaction between calcium chloride (CaCl2) and urea (CH4N2O) to precipitate as calcium carbonate (CaCO3). The EMCP method was evaluated using a test tube experiment, and the optimum combination of urease, urea, and calcium chloride was selected. It was used as preliminary data for the addition of the soybean as the catalyst. Concrete samples were prepared in the form of 5 cm x 10 cm cylindrical concrete, then crack on samples was made by Universal Testing Machine (UTM) with a controlled area that is in the range ± 0.2-0.3 mm. The injection solution was added to the concrete using the percolation method until the height of the solution was 5 mm above the concrete surface. The injection was carried out several times, and its effect on concrete cracks was evaluated through permeability tests, which can be used as one of the concrete quality parameters. The permeability coefficient value was inversely proportional to the quality, meaning that the smaller the permeability coefficient value, the better the concrete quality, and vice versa. The results showed that after the 4th injection, the total of calcite formed in the sample was 18.3% of the total surface area of the concrete crack, which was able to reduce the concrete permeability value by 95.43%. So that the use of soybean in the EMCP method is considered feasible for repairing concrete cracks.

Numerical Analysis on Pressure Drop and Heat Transfer in Nanofluids at Pore Length Scale in Open Metal Porous Structures with Kelvin Cells

In this paper, a numerical investigation in metal porous structures with Kelvin cell model is carried out on water/Al2O3 nanofluids using the single-phase model. The examined foams are characterized by a porosity of 0.95 and different values of cells per inch (CPI), equal to 10 and 20 CPI. Three different values of Al2O3 nanoparticle volume concentrations equal to 0, 2 and 4% are used. Results are presented and discussed in terms of pressure drop between the inlet and outlet sections. Furthermore, it has been possible to obtain a correlation used to find the value of permeability and drag coefficient for metal porous structures under investigation. It has been possible to notice how these two properties of the foam do not depend on the type of fluid but only on the geometric properties. In addition, the interfacial heat transfer coefficient between the fluid phase and the solid matrix has been estimated. In conclusion, the results in terms of Nusselt number as a function of Reynolds number based on the struct diameter show that it does not change varying the CPI values.

Determination of the permeability coefficient in the Darcy formula for liquid molding of thermal insulation products from quartz fibers

The results of water pouring of flat samples from chopped quartz fibers with a diameter of 12 microns and an elongation of 560…1680 are presented. Experimental values of water permeability coefficient through highly porous flat samples were obtained. The constant in the Kozeni-Karman permeability formula is determined depending on the porosity of the fiber layer.

Percutaneous Penetration and Metabolism of Plasticizers by Skin Cells and Its Implication in Dermal Exposure to Plasticizers by Skin Wipes.

Numerous studies focused on the human exposure to plasticizers via dermal contact; however, the percutaneous penetration of plasticizers was seldom considered in exposure assessment. In the present study, skin wipes of palms, back-of-hands, and forehead were collected from 114 participants (ages: 18-27). There was no significant difference between the levels of phthalates from palms and back-of-hand, while all phthalates collected from the forehead were significantly higher than those from palms and back-of-hand (p < 0.001); di(2-ethylhexyl)phthalate levels were substantially higher than other detected phthalates followed by di(n-butyl)phthalate and di(isobutyl)phthalate (DiBP), and for alternative plasticizers, bis-2-ethylhexyl terephthalate levels were substantially higher than acetyltributyl citrate and bis-2-ethylhexyladipate. Skin permeation and metabolism of phthalates was assessed using human skin equivalent models. The permeability coefficient (kp) values of phthalates were significantly negatively correlated with their log octanol-water partition coefficient (log Kow), while a significantly positive correlation was found between the log Kow and the cumulative amounts of phthalates in the cells. The proportion of phthalate intake via dermal exposure to skin wipes ranges from 1.3% (for dimethyl phthalate) to 8.6% (for DiBP) and suggests that dermal absorption is a significant route for adult phthalate exposure.