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Emission of semivolatile organic compounds (SVOCs) from source materials usually occurs very slowly in indoor environments due to their low volatility. When the SVOC emission process is controlled by external mass transfer, the gasphase concentration in equilibrium with the material (y(0)) is used as a key parameter to simplify the source models that are based on solid-phase diffusion. A material-air-material (M-A-M) configured microchamber method was developed to rapidly measure y(0) for a polyisocyanurate rigid foam material containing organophosphate flame retardants (OPRFs). The emission test was conducted in 44 mL microchambers for target OPFRs, including tris(2-chloroethyl) phosphate (CASRN: 115–96-8), tris(1-chloro-2-propyl) phosphate (CASRN: 13674–84-5), and tris(1,3-dichloro-2-propyl) phosphate (CASRN: 13674–87-8). In addition to the microchamber emission test, two other types of tests were conducted to determine y(0) for the same foam material: OPFR diffusive tube sampling tests from the OPFR source foam using stainless-steel thermal desorption tubes and sorption tests of OPFR on an OPFR-free foam in a 53 L small chamber. Comparison of parameters obtained from the three methods suggests that the discrepancy could be caused by a combination of theoretical, experimental, and computational differences. Based on the y(0) measurements, a linear relationship between the ratio of y(0) to saturated vapor pressure concentration and material-phase mass fractions has been found for phthalates and OPFRs.

Binder modification is an effective method to restrain the volume effect of Si anodes in high energy density lithium-ion batteries. In this work, a novel binder grafting strategy is proposed to prepare urea formaldehyde resin (UFR) grafted polyvinyl alcohol (PVA) binder to overall enhance the electrochemical performance of Si anodes. The advanced binder solves the problems of poor dispersibility, mechanical stability, and chemical stability of PVA binder. Benefit from the lithium conductivity and flexibility of the UFR modified PVA binder, the Si anode delivers over 2000 mAh/g after 200 cycles at a current density of 2.1 A/g, and retains 1837 mAh/g at 42 A/g. Furthermore, the PVA-UFR binder also exhibits obvious advantages in full cells, and the cycle stability of Si//LiFePO4 is significantly improved.

How to improve interface stabilization of silicon/silicon oxide anodes during the lithiation and delithiation process is a big challenge to promote their commercial utilization. In this work, a novel electrolyte additive of mesylethyl-methyl-pyrrolidinium (MEMP-DFOB) is reported, which helps to generate a beneficial film on the surface of silicon oxide-graphite (SiO/Gr) anode. Differential capacity vs. voltage (dQ/dV) results show that the film is formed at ~1.4 V. As a result, SiO/Gr anode based pouch full cells not only demonstrate enhanced discharge performance and cycling stability at −20 °C, but effectively inhibit gas releasing at high temperature of 45 and 60 °C, and successfully run over 900 cycles with a capacity retention of ~75 % at 45 °C. This strategy highlights a new way to develop SiO/Gr anode based lithium-ion batteries with outstanding performances at low and high temperature.

The material-phase diffusion coefficient (D(m)) and material/air partition coefficient (K(ma)) are the key parameters controlling the emissions of semivolatile organic compounds (SVOCs) from source materials. In indoor environments, air temperature is subject to change and can significantly affect the emission rates of SVOCs from building materials and consumer products. In this study, the emissions of organophosphate ester flame retardants (OPEFRs) from customized polyisocyanurate foam materials were measured in 44-mL microchambers at 23, 35, and 55 °C. The values of D(m) and K(ma) at different temperatures were determined. The results showed that the increase of temperature can significantly enhance the emissions of OPEFRs from the foam materials, and the emissions of OPEFRs were found to transfer from SVOC-type to volatile organic compound (VOC)-type with the increase of temperature. A correlation for OPEFRs between the steady-state emission rate and temperature and correlations between D(m), K(ma,) and temperature were obtained. The research results shed light on the effect of temperature on the mechanisms governing emissions of SVOCs.

A mechanistic model that considers particle dynamics and their effects on surface emissions and sorptions was developed to predict the fate and transport of phthalates in indoor environments. A controlled case study was conducted in a test house to evaluate the model. The model-predicted evolving concentrations of benzyl butyl phthalate in indoor air and settled dust and on interior surfaces are in good agreement with measurements. Sensitivity analysis was performed to quantify the effects of parameter uncertainties on model predictions. The model was then applied to a typical residential environment to investigate the fate of di-2-ethylhexyl phthalate (DEHP) and the factors that affect its transport. The predicted steady-state DEHP concentrations were 0.14 μg/m3 in indoor air and ranged from 80 to 46 000 μg/g in settled dust on various surfaces, which are generally consistent with the measurements of previous studies in homes in different countries. An increase in the mass concentration of indoor particles may significantly enhance DEHP emission and its concentrations in air and on surfaces, whereas increasing ventilation has only a limited effect in reducing DEHP in indoor air. The influence of cleaning activities on reducing DEHP concentration in indoor air and on interior surfaces was quantified, and the results showed that DEHP exposure can be reduced by frequent and effective cleaning activities and the removal of existing sources, though it may take a relatively long period of time for the levels to drop significantly. Finally, the model was adjusted to identify the relative contributions of gaseous sorption and particulate-bound deposition to the overall uptake of semi-volatile organic compounds (SVOCs) by indoor surfaces as functions of time and the octanol-air partition coefficient (Koa ) of the chemical. Overall, the model clarifies the mechanisms that govern the emission of phthalates and the subsequent interactions among air, suspended particles, settled dust, and interior surfaces. This model can be easily extended to incorporate additional indoor source materials/products, sorption surfaces, particle sources, and room spaces. It can also be modified to predict the fate and transport of other SVOCs, such as phthalate-alternative plasticizers, flame retardants, and biocides, and serves to improve our understanding of human exposure to SVOCs in indoor environments.

If Lakoff and Johnson (1980) convinced us of the ubiquity of metaphors in everyday thought and language, with Mixed Metaphors: Their Use and Abuse, Karen Sullivan shows us that mixing conceptual me...

This study investigated phthalate emissions from vinyl flooring in a large-scale chamber. Vinyl flooring materials were examined for their phthalates content; one with high contents of diisononyl phthalate (DINP) and di(2-ethylhexyl) phthalate (DEHP) was selected for emissions testing in a small chamber at two different temperatures. Using the same type of vinyl flooring, large-scale chamber experiments were then conducted in three testing phases. In the first phase, the gas-phase concentrations of DINP and DEHP in the large chamber at 36 °C were about three times lower than those in the small chamber under the same temperature, which is consistent with its lower area/volume ratio. In the second phase, when a large air mixing fan inside the chamber was replaced with a small fan, the gas-phase concentrations of DINP and DEHP in the large chamber were reduced slightly, due to the decease of mass transfer coefficient and emission rate. During the last phase, when the temperature of the chamber was reduced to 25 °C, phthalate concentrations dropped instantly and steeply due to the significantly reduced emissions. However, they did not decrease as quickly thereafter because of desorption of phthalates from the internal surfaces of the large chamber. A fundamental mechanistic model was developed to interpret the experimental results in the large chamber based on the emission characteristics obtained in the small chamber measurements. Reasonable agreement was obtained between the model calculation and experimental data. Further model simulations show that temperature and air mixing above the source material have important effects on the fate of phthalates, while the impact of air change rate (ACH) is not significant.

Infants spend most of their time sleeping, where they are in intimate contact with their crib mattresses. In this study, we analyzed the cover and foam layers of 20 new and used crib mattresses for selected chemical additives. Seventeen of the 20 crib mattress covers contained at least one identifiable plasticizer, with concentrations ranging from 1 to >35% by weight. Sixty percent of the covers contained a total plasticizer content of >9% by weight. Nine of the 20 covers contained either bis(2-ethylhexyl) phthalate (DEHP) or diisononyl phthalate (DINP). In contrast, phthalate alternatives, including diisononyl 1,2-cyclohexanedicarboxylic acid (DINCH) and bis(2-ethylhexyl) isophthalate (iso-DEHP), were the most frequently identified plasticizers in crib mattresses manufactured after the U.S. Consumer Product Safety Improvement Act (CPSIA) went into effect. Flame retardants, including pentabromodiphenyl ether (pentaBDE) congeners and triphenyl phosphate (TPP), and unreacted isocyanates (NCO) were also iden...

This study investigated the influences of surface sorption and air flow rate on the emission of phthalates from building materials. Controlled tests were conducted in specially designed stainless steel and wood chambers, and the steady-state concentration in the stainless steel chamber was about 2–3 times higher than that in the wood chamber for di(2-ethylhexyl) phthalate (DEHP) and diisononyl phthalate (DINP). The emission rate of phthalates increased in the wood chamber due to the diffusion mass flow through the chamber wall (i.e., surface absorption). The adsorption isotherm of phthalates on the stainless steel surface and the absorption parameters (i.e., diffusion and partition coefficients) of phthalates on the wood surface were determined experimentally, and the values were comparable to those in the literature. The equilibration time scale for phthalates absorbed to the sink reservoir in actual indoor environments was estimated and can be substantial (approximately 80 years), indicating that surface absorption may continuously drive phthalates from their indoor sources to various sinks and thus significantly increase the emission rate of phthalates. The gas-phase concentration of DEHP was measured in two stainless steel chambers operated at flow rates of 300 mL/min and 3000 mL/min, respectively, which were both adjusted to 1000 mL/min after steady state was reached. The gas-phase concentration of DEHP in the chamber was very sensitive to the chamber air flow rate, and higher air flow rates resulted in lower concentration levels. However, the increased emission rate compensated for the dilution in the gas phase and made the DEHP concentration not drop substantially with an increase in the air flow rate. Independently measured or calculated parameters were used to validate a semi-volatile organic compounds (SVOCs) emission model that included absorptive surfaces and for a range of air flow rates, with excellent agreement between the model predictions and the observed chamber concentrations of phthalates.

Emissions of phthalates and phthalate alternatives from vinyl flooring and crib mattress covers were measured in a specially designed chamber. The gas-phase concentrations versus time were measured at four different temperatures, that is, 25, 36, 45, and 55 °C. The key parameter that controls the emissions (y0, gas-phase concentration in equilibrium with the material phase) was determined, and the emissions were found to increase significantly with increasing temperature. Both the material-phase concentration (C0) and the chemical vapor pressure (Vp) were found to have great influence on the value of y0. The measured ratios of C0 to y0 were exponentially proportional to the reciprocal of temperature, in agreement with the van't Hoff equation. A emission model was validated at different temperatures, with excellent agreement between model calculations and chamber observations. In residential homes, an increase in the temperature from 25 to 35 °C can elevate the gas-phase concentration of phthalates by more than a factor of 10, but the total airborne concentration may not increase that much for less volatile compounds. In infant sleep microenvironments, an increase in the temperature of mattress can cause a significant increase in emission of phthalates from the mattress cover and make the concentration in the infant's breathing zone about four times higher than that in the bulk room air, resulting in potentially high exposure.

Understanding the sorption mechanisms for organophosphate flame retardants (OPFRs) on impervious surfaces is important to improve our knowledge of the fate and transport of OPFRs in indoor environments. The sorption processes of semivolatile organic compounds (SVOCs) on indoor surfaces are heterogeneous (multilayer sorption) or homogeneous (monolayer sorption). In this study, we adopted simplified Langmuir isotherm and Freundlich isotherm in a dynamic sink model to characterize the sorption dynamics of OPFRs on impervious surfaces such as stainless steel and made comparisons between the two models through a series of empty chamber studies. The tests involve two types of stainless steel chambers (53-L small chambers and 44-mL micro chambers) using tris(2-chloroethyl)phosphate (TCEP) and tris(1-chloro-2-propyl)phosphate (TCPP) as target compounds. Our test results show that the dynamic sink model using Freundlich isotherm can better represent the sorption process in the empty small chamber. Micro chamber test results from this study show that the sink model using both simplified Langmuir isotherm and Freundlich isotherm can well fit the measured gas-phase concentrations of OPFRs. We further applied both models and the parameters obtained to predict the gas phase concentrations of OPFRs in a small chamber with an emission source. Comparisons between model predictions and measurements demonstrate the reliability and applicability of the sorption parameters.

Retail stores contain a wide range of products that can emit a variety of indoor pollutants. Among these chemicals, phthalate esters and polybrominated diphenyl ethers (PBDEs) are two important categories, because they are extensively used as additives in consumer products and associated with serious health concerns. This study measured six phthalate and 14 PBDE compounds inside of 12 retail stores in Texas and Pennsylvania, U.S. Phthalates and PBDEs were widely found in the retail environment, indicating that they are ubiquitous indoor air pollutants. DEP, DnBP, and DEHP were the most abundant phthalates, with DnBP showing the highest concentration (0.23 ± 0.36 μg m −3 ). PBDEs were dominated by BDE-28, -99, and -209, having concentrations as high as 0.85 ± 1.99 ng m −3 (BDE-99). The levels of phthalates and PBDEs measured in this study are comparable to concentrations found in previous investigations of residential buildings, with phthalates showing lower concentrations and PBDEs exhibiting higher concentrations in retail stores. The potential co-occurrence of phthalates was not as strong as that of PBDEs, suggesting that phthalates might have more diverse sources. Whole building emission rates were calculated and showed similar patterns of variations as indoor air concentrations, suggestion the diversity of indoor sources of phthalates and PBDEs in retail environments.

Semi-volatile organic compounds (SVOCs) are indoor air pollutants that may have significant adverse effects on human health. Although emissions of volatile chemicals from building materials and consumer products are usually characterized in small chambers, few chamber studies have been conducted for SVOCs due to the challenges associated with analysis and the lack of validation procedures. There is an urgent need for a reliable and accurate chamber test method to verify these measurements. A reference method employing a specially-designed chamber has been developed and is undergoing extensive evaluation. A pilot inter-laboratory study (ILS) has been conducted with six laboratories performing chamber tests under identical conditions for di-2-ethylhexyl phthalate (DEHP). Results from this study showed inter-laboratory variations of 24% for DEHP emission rates, with closer agreement observed among intra-laboratory measurements for most of the participating laboratories. A mechanistic emission model fits well to the measured concentration profiles, demonstrating the feasibility of the proposed reference method to independently assess laboratory performance and validate SVOC emission tests.

A case study in a test house was conducted to investigate the fate and transport of benzyl butyl phthalate (BBzP) and di-2-ethylhexyl phthalate (DEHP) in residential indoor environments and the influence of temperature. Total airborne concentrations of phthalates were sensitive to indoor temperatures, and their steady-state concentration levels increased by a factor of 3 with an increase in temperature from 21 to 30 °C. Strong sorption of phthalates was observed on interior surfaces, including dust, dish plates, windows, mirrors, fabric cloth, and wood. Equilibrium partitioning coefficients for phthalates adsorbed to these surfaces were determined, and their values decreased with increasing temperature. For impervious surfaces, dimensionless partitioning coefficients were calculated and found to be comparable to reported values of the octanol-air partition coefficients of phthalates, Koa, suggesting that an organic film may develop on these surfaces. In addition, sorption kinetics was studied experimentally, and the equilibration time scale for impervious surfaces was found to be faster than that of fabric cloth. Finally, using an indoor fate model to interpret the measurement results, there was good agreement between model predictions and the observed indoor air concentrations of BBzP in the test house.

Phthalate emission from vinyl floorings was measured in specially designed stainless steel chambers. Phthalate concentrations increased and reached steady state after 2 to 5 days for all experiments. By having a high ratio of emission surface to sorption surface, avoiding mass loss of phthalates onto sampling pathways, and improving air mixing inside the chamber, the time to reach steady state was significantly reduced, compared to previous studies (1 to 5 months). An innovative approach was developed to determine y0, the gas-phase concentration of phthalates in equilibrium with the material phase, which is the key parameter controlling phthalate emissions. Target phthalate material-phase concentration (C0) and vapor pressure (Vp) were explicitly measured and found to have great influences on the y0 value. For low phthalate concentrations in materials, a simple partitioning mechanism may linearly relate y0 and C0, but cannot be evoked for high-weight phthalate percentages. In addition, the sorption kinetics and adsorption isotherm of phthalates on stainless steel chamber surfaces were determined experimentally. Independently measured or calculated parameters were used to validate a semivolatile organic compounds (SVOCs) emission model, with excellent agreement between model predictions and the observed chamber concentrations in gas and stainless steel phases. With the knowledge of y0 and emission mechanisms, human exposure to phthalates from tested floorings was assessed; the levels were comparable to previous studies. This work developed a rapid, novel method to measure phthalate emissions; emission measurement results can be connected to exposure assessment and help health professionals estimate screening-level exposures associated with SVOCs and conduct risk-based prioritization for SVOC chemicals of concern.

Retail stores contain a wide range of products that can emit a variety of indoor pollutants. Among these chemicals, phthalate esters and polybrominated diphenyl ethers (PBDEs) are two important categories of semi-volatile organic compounds (SVOCs). Filters in heating, ventilation, and air-conditioning (HVAC) system collect particles from large volumes of air and thus potentially provide spatially and temporally integrated SVOC concentrations. This study measured six phthalate and 14 PBDE compounds in HVAC filter dust in 14 retail stores in Texas and Pennsylvania, United States. Phthalates and PBDEs were widely found in the HVAC filter dust in retail environment, indicating that they are ubiquitous indoor pollutants. The potential co-occurrence of phthalates and PBDEs was not strong, suggesting that their indoor sources are diverse. The levels of phthalates and PBDEs measured in HVAC filter dust are comparable to concentrations found in previous investigations of settled dust in residential buildings. Significant correlations between indoor air and filter dust concentrations were found for diethyl phthalate, di-n-butyl phthalate, and benzyl butyl phthalate. Reasonable agreement between measurements and an equilibrium model to describe SVOC partitioning between dust and gas-phase is achieved.