Research Group and Activities


Developing nanotechnology to monitor contaminants

Contaminants of emerging concern, including cyanobacterial toxins, pharmaceuticals, pesticides, and personal care products, have been found in surface water bodies worldwide. These contaminants can be toxic and may cause health problems in humans and animals. Real-time monitoring of cyanobacterial toxins can be challenging. In order to monitor and prevent toxicity of these contaminants, Dr. Dion’s group is developing nanobiosensors with high sensitivity and selectivity to specific cyanobacterial toxins such as microcystin-LR, -LA, -YR, and -RR. In 2013, his group and collaborators developed a carbon nanotube-based electrochemical biosensor that can detect microcystin-LR (MC-LR) below the Environmental Protection Agency’s health advisory concentration limit of 0.3 μg/L. Currently, different biosensors using other advanced carbon materials, such as graphene, are in development to determine other cyanobacterial toxins in lower limits of detection. The group has also developed nanotechnology using titanium dioxide (TiO2) that is activated by light. The technology can help to decompose cyanotoxins, pesticides, and pharmaceuticals.


Identifying potential beneficial application of flue gas desulfurization gypsum

Flue gas desulfurization gypsum (FGDG) is a synthetic by-product produced in flue gas desulfurization systems of coal power plants. Due its chemical and physical properties, FGDG is used in beneficial applications. However, over the last decade, the utilization of FGDG has been decreased relative to the production, subsequently causing an environmental issue of FGDG disposal. This research evaluates the constituent release from FGDG under different environmental conditions.

Further, the aqueous phase and solid phase lead (Pb) stabilization by FGDG also be evaluated. The formation of different Pb precipitates at different pH values reduced the Pb levels in leachates.  The interactions between FGDG and main soil constituents related to Pb sorption characteristics is tested using laboratory synthesized ferrihydrite and commercially available humic acid. This research is performed in U.S. EPA Center Hill facility in collaboration with Dr.  Souhail Al-Abed.


Multiscale and Multitemporal Models to Simulate Absorption and Transport of Multiple Chemical Compounds in Skin Tissues

PhD. student Fang Yu is currently working with Dr. Gerald Kasting and Dr. Dionysios D. Dionysiou on multiscale and multitemporal models to simulate absorption and transport of multiple chemical compounds in different skin tissues. This work is not only critical to the evolving needs of transdermal and topical drug development, consumer product (e.g., cosmetics) development and risk assessment of chemical exposures, but also of broad scientific interest to advance our understanding of multiscale and multitemporal chemical transport in biological systems.  

Fang Yu’s work involves: (1) developing mechanistic models for different skin layers, sub layers and tissues using ordinary differential equations (ODE), partial differential equations (PDE) and empirical partitioning relationships through mass balance; (2) optimizing and validating parameters of the developed mechanistic models using experiment measurements through computational machine learning algorithms (e.g., simulated annealing and differential evolution) for nonlinear systems; and (3) identifying uncertainties and sensitivities of the developed models to input variables and parameters using global sensitivity and uncertainty analyses. The developed models, their validation and parameterizations, uncertainty and sensitivity analyses are implemented using gPROMs, R, Matlab, Python etc.


Developing an instrument for measuring aerosols

Dr. Dionysiou and colleagues are also developing a portable, powerful, and low-cost instrument for measuring element concentrations in aerosols.  The device uses microplasma spectroscopy to measure aerosols with nearly real-time results.  In this study, they introduced an aerosol preconcentration method that measures aerosols at absolute mass detection limits of a few nanograms. With this method, they collect aerosol on a tip of a microelectrode, ablate and atomize it using a pulsed spark plasma or glow discharge, and then detect the emission spectra. The instrument could be used for measuring carbon nanomaterials and toxic metal-containing particles in the workplace. The group is also using spectroscopic techniques to probe spatial and temporal evolution of the plasma used in this instrument to gain insights into plasma dynamics. We also conduct field studies on characterization of workers’ exposure to respirable particulate matters.

This research work is conducted in National Institute for Occupational Safety and Health (NIOSH).


A bio-oil wastewater sustainable treatment technology:  Organic acids generation from bio-oil wastewater

Lignocellulosic biomass based pyrolysis wastewater contains significant concentration of organic matter which is of high industrial value. However such wastewater is impossible for biodegradation. In order to take advantage of such wastewater, we are applying advanced oxidation process to it in a bench-scale reactor to make it biodegradable, such as hydrogen peroxide, Fenton, photo Fenton, etc.  Fenton pretreatment for 5 min is proven to be sufficient for 10 ml wastewater degradation due to the generation of highly oxidative hydroxyl radicals. Further study will be focused on the degradation mechanism of raw wastewater, fermentation and separation of organic acid, and improvement of our wastewater-organic acid generation system. Our work could provide rationale for non-biodegradable wastewater reuse and obtain value-added chemicals from waste realizing benefit maximization.


Effects of chemical oxidation on various Cyanobacteria at Differing Life Cycle Stages in Drinking Water Treatment

The focus of this project is to determine if the cyanobacterial life cycle stage influences the release of toxins upon exposure to DWT oxidants (ozone and chlorine) as well as the possible effects of environmental factors on the life cycle. This is being done through preliminary growth curve generation, in triplicate for each strain, and a flow through system using Corning 1000 mL Spinner Flasks. (Nutrient constraints were based upon Lake Erie ranges in the late summer.) Insight into these subjects will be gained by monitoring parameters such as cell density, photosynthetic activity, cell permeability/ integrity, and total/extracellular toxin concentrations while also utilizing the SEM and TEM microscopes to observe topography of cell surfaces and examine cell membranes respectively.

This project is supported through the USEPA Graduate Research Traineeship under Dr. Heath Mash.


Decomposition of Contaminants of Emerging Concern by UV-assisted Advanced Oxidation Process

The occurrence of contaminants of emerging concern in water and wastewater has brought up a serious issue to human health. Our group is using UV-254 nm direct photolysis and indirect photochemical treatment, i.e., UV + chlorine, UV + hydrogen peroxide, and UV + persulfate processes in a bench-scale UV collimated beam to degrade those contaminants. These homogeneous advanced oxidation technologies have been proved to be very effective in the destruction of a wide variety of organic compounds due to the generation of highly oxidative hydroxyl radical, chlorine radical, and/or sulfate radical. Significantly high removal efficiency of iodinated pharmaceuticals was achieved through UV + persulfate, while major algal toxins microcystin-LR and cylindrospermopsin could be removed rapidly by UV + chlorine. These results provide insights for the removal of contaminants in water and/or wastewater using these environmental friendly and cost effective technologies.


Quantification of Carbon Nanotubes through a Microwave Induced Heating Method

With widespread applications, the possibility of carbon nanotubes (CNTs) being released into the environment like other regulated industrial pollutants has increased. However, we generally do not have a specific method capable of determining quantities of CNTs in complex environmental matrices. It has been reported that CNTs display strong microwave absorption with intense heat release. The intense heat release from CNTs samples under microwave irradiation can lead to a temperature increase. As long as microwave power and exposure time remain constant, the temperature increase will be a function of CNTs present inside a sample. Thus, the main objective of our study is to set up a microwave system which can measure the temperature increase in environmental samples after microwave irradiation. The microwave heating responses of different types of CNTs (i.e. single-walled, multi-walled and carboxylated CNTs) in various environmental media, such as, soil, sediment and sludge, are studied. The microwave device could be applied for environmental quantification, and also investigations on bioaccumulation, toxicity and transport of CNTs in environmental and biological samples.

This research is being conducted through the Graduate Research Traineeship which is sponsored by the U.S. Environmental Protection Agency. Experiments are conducted at the U.S. EPA’s Center Hill Facility in collaboration with Dr. Souhail Al-Abed.


Human and Ecological Health Impacts Associated with Water Reuse:  Engineered Systems for Removing Priority Emerging Contaminants

In current project, advanced oxidation processes (AOPs), including UV-C/H2O2 and TiO2 photocatalysis, will be used to treat water samples from secondary effluent. A mixture of selected contaminants of emerging concern (ECs) (pharmaceuticals, antibacterials, perfluorinated compounds (PFCs), flame retardants, pesticides, hormones, disinfection by-products (DBPs), musks, and benzotriazoles) with their maximum concentrations reported in the environment will be spiked into the reverse osmosis (RO) effluents of GWRS (Scheme 1) to investigate the efficiency of these processes. The transformation products (TPs) of these contaminants and the toxicity of the treated effluent water will also be studied. In addition, two different UV sources, the most commonly used monochromatic germicidal low pressure-UV and newly developed mercury-free light-emitting diode (LED)-UV will be evaluated.


Degradation of Emerging Contaminants by Sulfate Radical-based Advanced Oxidation Process

Sulfate radical-based processes have been applied to remove various contaminants because of the high oxidation potential of sulfate radicals (and hydroxyl radicals) generated in such processes. Following our previous research on transition metal-based activation of peroxymonosulfate, sulfite activated by ferrites yielding sulfate radicals under solar light irradiation is being investigated in the current project. In such process, sulfite would decompose along with the target contaminants, which reduces the potential of secondary pollution caused by remaining oxidant such as peroxymonosulfate or persulfate. Ferrites are applied to catalyze sulfite because of their photocatalytic activity while their magnetic property can allow removal of the catalyst by magnetic field after degradation of the target contaminants. The Zn-based ferrites show high activity catalyzing sulfite to degrade a classic refractory herbicide—atrazine, and a major algal toxin—microcystin-LR. The study includes mechanistic fundamental studies to elucidate the generation of sulfate radicals and hydroxyl radicals and the formation of intermediate products. This project concerns a novel and environmental friendly technology for the simultaneous removal of sulfite and recalcitrant contaminants at neutral pH in water and/or wastewater.


Implication of Nanomaterials in consumer products 

My research interests are mainly on implication of Nanomaterials (NMs) in consumer products such as in textiles, food and food storage, cosmetics (sprays), household chemicals (paints, sprays), sports equipment and dental equipment. Markets surveys identified Silver, Zinc Oxide, Titanium Oxide, Carbon, and silica as the species that are most frequently used as NMs in consumer products. There are important NM properties (particle size, particle size distribution, chemical composition, mass loading, interaction with matrix, interaction with water and other solvents) we should take into consideration in order to better understand aspects related to release of NMs from consumer products. Effort also is needed to understand their fate, transport and implications in environmental systems and living organisms.

This research is sponsored by Egyptian Cultural and Educational Bureau and UC. As well as, it administered through UC. Experiments are conducted at the U.S. EPA’s, Center Hill in collaboration with Dr. Souhail Al-Abed.

Optimizing Culturing of Toxin-producing Cyanobacteria.

It is widely known that Harmful Algal Blooms (HABs) are detrimental to drinking water supplies and recreation due to the release of various toxins. Recent increases in frequency and intensity of HABs in Lake Erie and other water bodies have resulted in a growing demand for research into these events. With a better understanding of the organisms that cause these issues, scientists and engineers will be better able to manage blooms. Such research requires an expansion of USEPA’s Cyanobacteria culture program. The focus of this work is to optimize growth and cyanotoxin production by analyzing specific variables namely, Nitrogen and Phosphorus concentrations in growth media as well as light intensity, diurnal cycles, and gas flow rates. This work has a wide range of applications from toxicology to water treatment.

This research is being conducted through the Graduate Research Traineeship which is sponsored by the U.S. Environmental Protection Agency and administered through UC. Experiments are conducted at the U.S. EPA’s Andrew W. Breidenbach Environmental Research Center (AWBERC) in collaboration with Dr. Joel Allen and Nicholas Dugan.


Ferrite Composite as a Photocatalyst for Removing Cyanotoxins

Recent years have seen increasing algal blooms worldwide, which mainly caused by the pollution of surface water and global climate change. However, current water treatment systems are not capable of fully removing cyanotoxins which were released into water resources by the harmful algal blooms. Titanium dioxide, which acts as a photocatalyst in advanced oxidation process, is believed to be a promising material in the field of environmental remediation. But the low photocatalytic activity under visible light has been a bottleneck that limits the practical application of titanium dioxide. In Dr. Dionysiou’s research group, we are trying to couple titanium dioxide with ferrites, which are magnetic semiconductors with short band gap. The composite materials offer photocatalytic activity under visible light, easy separation by magnet, and reusability. The novel photocatalytic materials are effective in the degradation of the emerging contaminants including cyanotoxins.


Purifying wastewater with a novel bimetallic particle 

Bimetallic particles, or the fusion of two metals into one, have become popular in the treatment of wastewater and groundwater. Yet current particles, such as zero-valent iron (ZVI), do not perform well in neutral pH conditions and the alternatives are often costly. In this project, visiting professor Dr. Fenglian Fu and colleagues are developing a novel, low-cost bimetallic particle made of a core metal (aluminum) and a second metal (iron). They are using this particle to remove Cr(VI) from wastewater in a wide range of pH conditions. Their tests so far have shown that the Fe/Al bimetal has been effective in treating wastewater in varying pH levels, indicating that this particle could meet the demands for rapid and stable Cr(VI) removal in wastewater treatment.


Removing humic acids from drinking water

Humic acids (HA) can make drinking water discolored, and give it an undesirable taste and odor when they react with the chlorine in water during the drinking water treatment process. This reaction can also produce potential carcinogens such as trihalomethanes and haloacetic acids. Dr. Dionysiou and his colleagues are attempting to remove HAs from drinking water by using adsorption, which is considered the major cause of pollutant deactivation. The removal of the acids is important to both inhibit their toxic properties and restricting their transport in water systems.

His team is using an adsorbent with a high adsorption capacity that can recover easily, making it more practical than other adsorbents to use in the near future.   In particular, they are developing adsorbents with positively charged groups that can efficiently remove HAs. In a detailed study, the group monitored the interaction of HAs with the positively charged adsorbents using adsorption tests and surface characterization techniques.


Treating contaminants in water using oxidation

The hygiene products we use every day, like shampoo, perfume, and sunscreen, have become one of the biggest contaminants in water today. Because these products are used daily, and also can be resistant to traditional water treatment technology, they carry a huge risk to the health of our bodies and our environment.

Dr. Dionysiou and his team are exploring new means for removing these contaminants with Advanced Oxidation Processes, or AOPs. AOPs are fast, environmentally friendly, and they produce fewer by-products. Currently, his team is using the UV-254nm/H2O2 AOP to destroy an organic UV filter, one that is widely used, persistent in the environment, and can be disruptive to the endocrine system. During this process, reactive oxygen species initiate the destructive process of a water pollutant using hydrogen abstraction, electron transfer and other mechanisms. His team is also studying the behavior of the contaminants during the treatment process by exploring transformation products and reaction pathways.


Jar Testing for Strontium Removal

The element strontium is included on the U.S. EPA’s Contaminant Candidate List 3, making it open for future regulatory action. The focus of this project is on the effectiveness of coagulation (aluminum and iron) and lime softening on strontium removal through jar testing. Jar testing is a bench-scale process that mimics the full-scale water treatment processes of coagulation and sedimentation. The effects of different treatment parameters can be determined and optimized for a contaminant’s removal. Such information will be useful in determining the regulatory process and in monitoring water systems that have high strontium levels. Aqueous elemental content (ICP-AES) and solids analysis for mineralogy (XRD) and/or crystal structure (SEM) will be conducted as well.

This research is being conducted through the Graduate Research Traineeship which is sponsored by the U.S. Environmental Protection Agency and administered through UC. Experiments are conducted at the U.S. EPA’s Andrew W. Breidenbach Environmental Research Center (AWBERC) in collaboration with Dr. Darren Lytle.


Testing Drinking Water with Microelectrodes

In another project, the researchers are applying microelectrodes in a novel way to measure the pH, dissolved oxygen, and free chlorine in drinking water samples. Because microelectrodes are small in size, they are useful in corrosion research as they do not damage the materials being investigated. The microelectrodes can also examine water chemistry conditions within microns of the pipe’s surface. These conditions may differ from that of the bulk water, thereby revealing additional information on the processes of metal corrosion. This study aims to further elucidate the mechanisms of corrosion and how to limit corrosion in drinking water through microelectrode investigation.

This research is being conducted through the Graduate Research Traineeship which is sponsored by the U.S. Environmental Protection Agency and administered through UC. Experiments are conducted at the U.S. EPA’s Andrew W. Breidenbach Environmental Research Center (AWBERC) in collaboration with Dr. Darren Lytle, Dr. Jonathan Pressman, and Dr. David Wahman.