Mei Sun

University of North Carolina at Charlotte | UNC Charlotte · Department of Civil and Environmental Engineering

Anti-fog sprays and solutions are used on eyeglasses to minimize the condensation of water vapor, particularly while wearing a mask. Given their water-repellent properties, we sought to characterize per- and polyfluorinated alkyl substance (PFAS) compounds in four anti-fog spray products, five anti-fog cloth products, and two commercial fluorosurfa...

Ion exchange (IX) is a promising technology to remove legacy anionic per- and polyfluoroalkyl substances (PFAS) from water. As increasing numbers of per- and polyfluoroalkyl ether acids (PFEA) and other emerging PFAS were detected in the environment, it is necessary to understand how well IX resins remove these emerging PFAS for drinking water trea...

The UV-sulfite reductive treatment using hydrated electrons (eaq-) is a promising technology for destroying perfluorocarboxylates (PFCAs, CnF2n+1COO-) in any chain length. However, the C-H bonds formed in the transformation products strengthen the residual C-F bonds and thus prevent complete defluorination. Reductive treatments of fluorotelomer car...

Contamination of drinking water by per- and polyfluoroalkyl substances (PFASs) emitted from manufacturing plants, fire-fighting foams, and urban waste streams has received considerable attention due to concerns over toxicity and environmental persistence; however, PFASs in ambient air remain poorly understood, especially in the United States (US)....

We evaluated the efficacy of granular activated carbon (GAC) adsorption for mitigating formation of chlorine disinfection byproducts (DBPs) in water with a wide range of bromide (20–1000 μg L−1) and iodide (<5–100 μg L−1) concentrations. GAC effectiveness was assessed by determining speciated total organic halogen (TOX), 70 DBPs, and calculated cyt...

Here we synthesize current understanding of the magnitudes and methods for assessing human and wildlife exposures to poly‐ and perfluoroalkyl substances (PFAS). Most human exposure assessments have focused on two to five legacy PFAS and wildlife assessments are typically limited to targeted PFAS (up to ~30 substances). However, shifts in chemical p...

Heterogeneous Fenton dominated by ·OH is limited in its application, as pre-acidification is required to maximize the generation amount and redox potential of ·OH. It is thus featured to consume resources and generate pollutants. In this study, both CuS/H2O2 and Cu2S/H2O2 are found to show better performances under close-to-neutral condition (pH 5....

A Pd/MnO2/Ni foam electrode with hierarchical structure was synthesized via electrodeposition for efficient electrocatalytic hydrodechlorination. Compared with the ordinary Pd/Ni foam electrode, the introduction of MnO2 greatly enhanced the catalytic reactivity and reduced the dose of precious metal Pd. Only a quarter of Pd was required for the Pd/...

For several decades, a common processing aid in the production of fluoropolymers was the ammonium salt of perfluorooctanoic acid (PFOA). Because PFOA is persistent, bioaccumulative, and toxic, its production and use are being phased out in the United States. In 2009, the US Environmental Protection Agency stipulated conditions for the manufacture a...

There have been reports of North American landfills that are experiencing temperatures in excess of 80 − 100°C. However, the processes causing elevated temperatures are not well understood. The objectives of this study were to develop a model to describe the generation, consumption and release of heat from landfills, to predict landfill temperature...

Long-chain per- and polyfluoroalkyl substances (PFASs) are being replaced by short-chain PFASs and fluorinated alternatives. For ten legacy PFASs and seven recently discovered perfluoroalkyl ether carboxylic acids (PFECAs), we report (1) occurrence in the Cape Fear River (CFR) watershed, (2) fate in water treatment processes, and (3) adsorbability...

Large volumes of sulfur-containing wastes enter municipal solid waste landfills each year. Under the anaerobic conditions that prevail in landfills, oxidized forms of sulfur, primarily sulfate, are converted to sulfide. Hydrogen sulfide (H2S) is corrosive to landfill gas collection and treatment systems, and its presence in landfill gas often neces...

Recent USEPA data show that 1,4-dioxane is frequently detected in US drinking water derived from both groundwater and surface water. 1,4-Dioxane is a likely human carcinogen, and an excess 10-6 cancer risk is associated with a drinking water concentration of 0.35 μg/L. To support 1,4-dioxane occurrence investigations, source identification and expo...

Landfills that accept municipal solid waste (MSW) in the U.S. may also accept a number of sulfur-containing wastes including residues from coal or MSW combustion, and construction and demolition (C&D) waste. Under anaerobic conditions that dominate landfills, microbially mediated processes can convert sulfate to hydrogen sulfide (H2S). The presence...

Brines generated from oil and natural gas production, including flowback water and produced water from hydraulic fracturing of shale gas, may contain elevated concentrations of bromide (∼1 g/L). Bromide is a broad concern due to the potential for forming brominated disinfection byproducts (DBPs) during drinking water treatment. Conventional treatme...

Carbon electrodes are proposed in reactive sediment caps for in situ treatment of contaminants. The electrodes produce reducing conditions and H(2) at the cathode and oxidizing conditions and O(2) at the anode. Emplaced perpendicular to seepage flow, the electrodes provide the opportunity for sequential reduction and oxidation of contaminants. The...

Sediment caps that degrade contaminants can improve their ability to contain contaminants relative to sand and sorbent-amended caps, but few methods to enhance contaminant degradation in sediment caps are available. The objective of this study was to determine if, carbon electrodes emplaced within a sediment cap at poised potential could create a r...