Sorption kinetics of parent and substituted PAHs for low-density polyethylene (LDPE): Determining their partition coefficients between LDPE and water (KLDPE) for passive sampling

A passive sampler for synchronously measuring inorganic and organic pollutants in sediment porewater: Configuration and field application

In situ measurement of multiple pollutants coexisting in sediment porewater is an essential step in comprehensively assessing the bioavailability and risk of pollutants, but to date, this needs to be better developed. In this study, a passive sampler, consisting of an "I-shaped" supporting frame and inorganic/organic sampling units, incorporating equilibrium dialysis theory and kinetic/equilibrium sorption principle, was developed for the synchronous measurement of inorganic (e.g., phosphorus and metal(loid)s) and organic pollutants (e.g., parent and substituted PAHs). The equilibrium time and sampling rates were explored in laboratory tests to support in situ application. Profiles of pollutants in porewater within a vertical resolution of centimeters, i.e., 1 cm and 2 cm for inorganic and organic pollutants, respectively, were obtained by field deployment of the sampler for further estimation of diffusive fluxes across the sediment-water interface. The results suggested that the role of sediments for a specific pollutant may change (e.g., from "sink" to "source") during the sampling time. This study demonstrated the feasibility of synchronous measurement of inorganic and organic pollutants in sediment porewater by the passive sampler. In addition, it provided new insight for further investigation into the combined pollution effects of various pollutants in sediments.

Environmental risks of disposable face masks during the pandemic of COVID-19: Challenges and management

Since the COVID-19 outbreak in early 2020, face mask (FM) has been recognized as an effective measure to reduce the infection, increasing its consumption across the world. However, the large amount of at-home FM usage changed traditional medical waste management practices, lack of improper management. Currently, few studies estimate FM consumption at a global scale, not to say a comprehensive investigation on the environmental risks of FM from a life cycle perspective. Therefore, global FM consumption and its associated environmental risks are clarified in the present study. Our result shows that 449.5 billion FMs were consumed from January 2020 to March 2021, with an average of 59.4 FMs per person worldwide. This review also provides a basis to understand the environmental risk of randomly disposed of FM and highlights the urgent requirement for the attention of FMs waste management to prevent pollution in the near future.

Development of novel experimental and modelled low density polyethylene (LDPE)-water partition coefficients for a range of hydrophobic organic compounds

Knowledge about partitioning constants of hydrophobic organic compounds (HOCs) between the polymer and aqueous phases is critical for assessing chemical environmental fate and transport. The conventional experimental method is characterized by large discrepancies in the measured values due to the limited water solubility of HOCs and other associated issues. In the current work, a novel three-phase partitioning system was evaluated to determine accurate low-density polyethylene (LDPE)-water partition coefficients (K_PE-w). By adding sufficient surfactant (Brij 30) to form the micellar pseudo-phase within the polymer/water system, the K_PE-w values were obtained from a combination of two experimentally measured values, that is, the micelle-water partition coefficient (K_mic-w) and the LDPE-micelle partition coefficient (K_PE-mic). The method presented here is capable of shortening the equilibration time to half a month, and avoiding defects of the traditional method with respect to directly measured aqueous phase concentrations. Herein, the K_PE-w values were determined for HOCs with little errors. Meanwhile, based on the 120 experimental K_PE-w data, several in silico models were also developed as valid extrapolation tools to estimate missing or uncertain values. Analysis of the underlying solubility interactions in the nonionic surfactant micelles were investigated, providing additional support for the reliability of the proposed method.

COVID-19 discarded disposable gloves as a source and a vector of pollutants in the environment

The appearance of the virus SARS-CoV-2 at the end of 2019 and its spreading all over the world has caused global panic and increase of personal protection equipment usage to protect people against infection. Increased usage of disposable protective gloves, their discarding to random spots and getting to landfills may result in significant environmental pollution. The knowledge concerning possible influence of gloves and potential of gloves debris on the environment (water, soil, etc.), wildlife and humans is crucial to predict future consequences of disposable gloves usage caused by the pandemic. This review focuses on the possibility of chemical release (heavy metals and organic pollutants) from gloves and gloves materials, their adsorptive properties in terms of contaminants accumulation and effects of gloves degradation under environmental conditions.

Net volatilization of PAHs from the North Pacific to the Arctic Ocean observed by passive sampling

The North Pacific-Arctic Oceans are important compartments for semi-volatile organic compounds' (SVOCs) global marine inventory, but whether they act as a "source" or "sink" remains controversial. To study the air-sea exchange and fate of SVOCs during their poleward long-range transport, low-altitude atmosphere and surface seawater were measured for polycyclic aromatic hydrocarbons (PAHs) by passive sampling from July to September in 2014. Gaseous PAH concentrations (0.67-13 ng m^-3) were dominated by phenanthrene (Phe) and fluorene (Flu), which displayed an inverse correlation with latitude, as well as a significant linear relationship with partial pressure and inverse temperature. Concentrations of PAHs in seawater (1.8-16 ng L^-1) showed regional characteristics, with higher levels near the East Asia and lower values in the Bering Strait. The potential impact from the East Asian monsoon was suggested for gaseous PAHs, which - similar to PAHs in surface seawater - were derived from combustion sources. In addition, the data implied net volatilization of PAHs from seawater into the air along the entire cruise; fluxes displayed a similar pattern to regional and monthly distribution of PAHs in seawater. Our results further emphasized that air-sea exchange is an important process for PAHs in the open marine environments.

Assessment of commercial porous polyethylene frit for extraction of polycyclic aromatic hydrocarbons from water

Exploring commercial and inexpensive sorbents for extraction of organic pollutants is still an active area of research. Ultrahigh molecular weight polyethylene sieve plate (UMPESP) is a commercially available, low-cost, and porous frit, which has been widely used in solid-phase extraction cartridges to fix the filling materials. In this work, UMPESP was investigated for the extraction of polycyclic aromatic hydrocarbons (PAHs) from water samples. The desorption and sorption efficiencies of UMPESP were first evaluated and compared with two previously reported sorbents, low-density polyethylene plastic pellet (LDPEP) and silicone rod (SR). The comparative results showed that quantitative desorption of analytes from UMPESP, which could be easily achieved with 2 × 1.5 mL n-hexane, was more effective than that of LDPEP (>6 × 1.5 mL n-hexane) and comparable to that of SR. Additionally, shorter equilibrium time was rendered by UMPESP (shaking for 120 min) compared with SR (>480 min), due to the porous structure and larger surface area of the former. Different parameters that affect the extraction efficiency, including organic modifier, ionic strength, and pH value, were then studied. The optimized method coupled with gas chromatography-mass spectrometry afforded good linearity in a concentration range of 10-5000 ng L^-1 (except acenaphthene in the range of 25-5000 ng L^-1) with coefficients of determination ranging from 0.9957 to 0.9995 and relative standard deviations below 13.8%. The limits of detection and quantification were 0.04-3.35 ng L^-1 and 0.13-11.16 ng L^-1, respectively. Finally, the method was successfully applied to determine PAHs in real water samples, and the results showed no statistically significant difference with the concentrations derived from liquid-liquid extraction.

Dielectric and AC Breakdown Properties of SiO2/MMT/LDPE Micro–Nano Composites

Low-density polyethylene (LDPE) is an important thermoplastic material which can be made into films, containers, wires, cables, etc. It is highly valued in the fields of packaging, medicine, and health, as well as cables. The method of improving the dielectric property of materials by blending LDPE with inorganic particles as filler has been paid much attention by researchers. In this paper, low-density polyethylene is used as the matrix, and montmorillonite (MMT) particles and silica (SiO2) particles are selected as micro and nano fillers, respectively. In changing the order of adding two kinds of particles, a total of five composite materials were prepared. The crystallization behavior and crystallinity of five kinds of composites were observed, the εr and tanδ changes of each material were investigated with frequency and temperature, and the power frequency (50 Hz) AC breakdown performance of materials were measured. The differential scanning calorimetry (DSC) and X-ray diffraction (XRD) results show that the crystallinity of the composites is higher than that of LDPE. Experimental data of dielectric frequency spectra show that the dielectric constants of micro–nano composites and composites with added MMT particles are lower than LDPE, the dielectric loss of composites can be improved by adding MMT particles. The experimental data of dielectric temperature spectra show that the permittivity of SiO2-MMT/LDPE is still at a low level under the condition of 20~100 °C. In terms of breakdown field strength, the SiO2/LDPE composite material increased by about 17% compared with the matrix LDPE, and the breakdown field strength of the materials SiO2-MMT/LDPE and MMT-SiO2/LDPE increased by about 6.8% and 4.6%, respectively.

Design, Simulation, and Environmental Assessment of an Adsorption-Based Treatment Process for the Removal of Polycyclic Aromatic Hydrocarbons (PAHs) from Seawater and Sediments in North Colombia

The presence of marine pollution in Cartagena Bay (Colombia) is an alarming environmental issue because of the ecotoxicological properties of contaminants such as polycyclic aromatic hydrocarbons (PAHs) that may affect the biodiversity of coastal ecosystems. In this sense, there is a need to propose alternatives to remediate the environmental pollution of such bodies of water. The aim of this work was to design an adsorption-based treatment process for the removal of PAHs from seawater and sediments. Two design cases were considered: (i) a base process without a PAH desorption unit and (ii) an alternative process including a PAH desorption unit. Both designs were simulated using Aspen Plus to obtain mass and energy balances. A parametric sensitivity analysis was carried out to determine optimum operating conditions for solvent recovery and treatment efficiency. The pressure and temperature of evaporators were selected as key parameters, as well as PAH loads in the influent. The environmental performance of base and alternative designs was also evaluated via waste reduction algorithm (WAR) methodology. A maximum recovered solvent flow rate was found when the evaporator operates at 56 °C and 0.81-0.83 atm. In addition, the total generation rate of potential environmental impacts (PEI) reported negative values for cases 1, 3, and 4 (-9.80 × 10^-1, -9.25 × 10⁺¹, -1.19 × 10⁺¹, and 1.04 × 10⁺¹ PEI/h). The major concern derived from this analysis is the high environmental impacts reached by the photochemical oxidation potential (PCOP) category associated with the use of hexane and acetone as solvents during PAH removal from sediments. In general, both designs of seawater and sediment treatment seem to be an environmentally friendly alternative for marine pollution remediation.