Dion Dionysiou - Academia.edu (original) (raw)

Papers by Dion Dionysiou

Environmental Chemistry Letters, 2022

Research on plastic pollution has recently evidenced the ubiquitous presence of tiny plastic part... more Research on plastic pollution has recently evidenced the ubiquitous presence of tiny plastic particles called microplastics. Microplastics alter organisms because microplastics tend to bioaccumulate, they contain hazardous additives, and they carry other contaminants and pathogens adsorbed on their surface. Here, we review the biodegradation of the five most common microplastics: polyethylene, polypropylene, polyvinyl chloride, polyethylene terephthalate, and polystyrene. Despite the fact that most plastics are hardly biodegradable, biodegradation is still a popular remediation techniques because it is highly economical and environmentally friendly. Biodegradation can be done applying single or combined bio-cultures such as bacteria, mold, yeast, and algae. We present analytical and microbiological methods used for monitoring microplastic biodegradation. Actually, no microbial method removes completely microplastics from the environment within a reasonable time interval. As a consequence, the last developments combine biodegradation with other methods such as membrane filtration.

Cost metrics can include levelized costs of water treatment as well as individual cost components... more Cost metrics can include levelized costs of water treatment as well as individual cost components, such capital or operations and maintenance (O&M) costs. Energy Performance Energy performance metrics can include the total energy requirements of the water treatment process, the type of energy required (e.g., thermal vs. electricity), embedded energy in chemicals and materials, and the degree to which alternative energy resources are utilized. Water Treatment Performance Water treatment performance metrics can include the percent removal of various contaminants of concern and the percent recovery of water from the treatment train. Human Health and Environment Externalities Externality metrics can include air emissions, greenhouse gas emissions, waste streams, societal and health impacts, land-use impacts. Process Adaptability Process adaptability metrics can include the ability to incorporate variable input water qualities, the ability to incorporate variable input water quantity flows, the ability to produce variable output water quality, and the ability to operate flexibly in response to variable energy inputs.

I n t r o d u c t I o n Clean water is critical to ensure good health, strong communities, vibran... more I n t r o d u c t I o n Clean water is critical to ensure good health, strong communities, vibrant ecosystems, and a functional economy for manufacturing, farming, tourism, recreation, energy production, and other sectors' needs. Research to improve desalination technologies can make nontraditional sources of water (i.e., brackish water; seawater; produced and extracted water; and power sector, industrial, municipal, and agricultural wastewaters) a cost-effective alternative. These nontraditional sources can then be applied to a variety of beneficial end uses, such as drinking water, industrial process water, and irrigation, expanding the circular water economy by reusing water supplies and valorizing constituents we currently consider to be waste. As an added benefit, these water supplies could contain valuable constituents that could be reclaimed to further a circular economy. I n t r o d u c t I o n 1.2. Pipe-Parity and Baseline Definitions A core part of NAWI's vision of a circular water economy is reducing the cost of treating nontraditional source waters to the same range as the portfolio of accessing new traditional water sources, essentially achieving pipe-parity. The costs considered are not just economic but include consideration of energy consumption, system reliability, water recovery, and other qualitative factors that affect the selection of a new water source. To effectively assess R&D opportunities, pipeparity metrics are utilized; they encompass a variety of information that is useful to decision makers regarding investments related to different source water types. Pipe-parity is defined as technological and non-technological solutions and capabilities that make marginal water sources viable for end-use applications. Like the concept of grid parity (where an alternative energy source generates power at a levelized cost of electricity [LCOE] that is less than or equal to the price of power from the electricity grid), a nontraditional water source achieves pipe-parity when a decision maker chooses it as their best option for extending its water supply. Specific pipe-parity metrics of relevance can include: Cost Cost metrics can include levelized costs of water treatment as well as individual cost components, such as capital or operational and maintenance (O&M) costs. Energy Performance Energy performance metrics can include the total energy requirements of the water treatment process, the type of energy required (e.g., thermal vs. electricity), embedded energy in chemicals and materials, and the degree to which alternative energy resources are utilized. Water Treatment Performance Water treatment performance metrics can include the percent removal of various constituents of concern and the percent recovery of water from the treatment train. Human Health and Environment Externalities Externality metrics can include air emissions, greenhouse gas emissions, waste streams, societal and health impacts, and land-use impacts. Process Adaptability Process adaptability metrics can include the ability to incorporate variable input water qualities, incorporate variable input water quantity flows, produce variable output water quality, and operate flexibly in response to variable energy inputs. I n t r o d u c t I o n Seawater and Ocean Water Water from the ocean or from bodies strongly influenced by ocean water, including bays and estuaries, with a typical total dissolved solids (TDS) between 30,000 and 35,000 milligrams per liter (mg/L). Brackish Groundwater Water pumped from brackish aquifers, with particular focus on inland areas where brine disposal is limiting. Brackish water generally is defined as water with 1-10 grams per liter (g/L) of total dissolved solids (TDS). Industrial Wastewater Water from various industrial processes that can be treated for reused Municipal Wastewater Wastewater treated for reuse through municipal resource recovery treatment plants utilizing advanced treatment processes or decentralized treatment systems Agricultural Wastewater Wastewater from tile drainage, tailwater, and other water produced on irrigated croplands, as well as wastewater generated during livestock management, that can be treated for reuse or disposal Mining Wastewater Wastewater from mining operations that can be reused or prepared for disposal Produced Water Water used for or produced by oil and gas exploration activities (including fracking) that can be reused or prepared for disposal Power and Cooling Wastewater Water used for cooling or as a byproduct of treatment (e.g., flue gas desulfurization) that can be reused or prepared for disposal These nontraditional water sources range widely in TDS (100 milligrams per liter [mg/L]-800,000 mg/L total) as well as the type and concentrations of contaminants (e.g., nutrients, hydrocarbons, organic compounds, metals). These different water supplies require varying degrees of treatment to reach reusable quality.

Water Research, 2016

Visible light (VIS) photocatalysis has large potential as a sustainable water treatment process, ... more Visible light (VIS) photocatalysis has large potential as a sustainable water treatment process, however the reaction pathways and degradation processes of organic pollutants are not yet clearly defined. The presence of cyanobacteria cause water quality problems since several genera can produce potent cyanotoxins, harmful to human health. In addition, cyanobacteria produce taste and odor compounds, which pose serious aesthetic problems in drinking water. Although photocatalytic degradation of cyanotoxins and taste and odor compounds have been reported under UV-A light in the presence of TiO 2 , limited studies have been reported on their degradation pathways by VIS photocatalysis of these problematic compounds. The main objectives of this work were to study the VIS photocatalytic degradation process, define the reactive oxygen species (ROS) involved and elucidate the reaction mechanisms. We report carbon doped TiO 2 (C-TiO 2) under VIS leads to the slow degradation of cyanotoxins, microcystin-LR (MC-LR) and cylindrospermopsin (CYN), while taste and odor compounds, geosmin and 2-methylisoborneol, were not appreciably degraded. Further studies were carried-out employing several specific radical scavengers (potassium bromide, isopropyl alcohol, sodium azide, superoxide dismutase and catalase) and probes (coumarin) to assess the role of different ROS (hydroxyl radical • OH, singlet oxygen 1 O 2 , superoxide radical anion O 2 •−) in the degradation processes. Reaction pathways of MC-LR and CYN were defined through identification and monitoring of intermediates using liquid chromatography tandem mass spectrometry (LC-MS/MS) for VIS in comparison with UV-A photocatalytic treatment. The effects of scavengers and probes on the degradation process under VIS, as well as the differences in product distributions under VIS and UV-A, suggested that the main species in VIS photocatalysis is O 2 •− , with • OH and 1 O 2 playing minor roles in the degradation.

Journal of Hazardous Materials, 2015

h i g h l i g h t s • UV-254 nm/H 2 O 2 AOP was utilized for the degradation and mineralization o... more h i g h l i g h t s • UV-254 nm/H 2 O 2 AOP was utilized for the degradation and mineralization of PBSA and BSA. • Promotion of k obs with [H 2 O 2 ] 0 ≤ 4 mM and inhibition at higher [H 2 O 2 ] 0 were observed. • The S and N were released and monitored as SO 4 2− and NH 4 + , respectively. • Br − inhibited both the degradation and mineralization much more significantly than Cl − .

RSC Adv., 2015

Granular activated carbon (GAC) particles can be shaped into an integrated 3D-anode using PVDF bi... more Granular activated carbon (GAC) particles can be shaped into an integrated 3D-anode using PVDF binder and electro oxidation of reactive dyes in a three-dimensional flow-through carbon anode reactor (TDFCR) delivers a clean effluent free from carbon dust.

Water Research, 2012

The destruction of the commonly found cyanobacterial toxin, microcystin-LR (MC-LR), in surface wa... more The destruction of the commonly found cyanobacterial toxin, microcystin-LR (MC-LR), in surface waters by UV-C/H(2)O(2) advanced oxidation process (AOP) was studied. Experiments were carried out in a bench scale photochemical apparatus with low pressure mercury vapor germicidal lamps emitting at 253.7 nm. The degradation of MC-LR was a function of UV fluence. A 93.9% removal with an initial MC-LR concentration of 1 μM was achieved with a UV fluence of 80 mJ/cm(2) and an initial H(2)O(2) concentration of 882 μM. When increasing the concentration of MC-LR only, the UV fluence-based pseudo-first order reaction rate constant generally decreased, which was probably due to the competition between by-products and MC-LR for hydroxyl radicals. An increase in H(2)O(2) concentration led to higher removal efficiency; however, the effect of HO scavenging by H(2)O(2) became significant for high H(2)O(2) concentrations. The impact of water quality parameters, such as pH, alkalinity and the presence of natural organic matter (NOM), was also studied. Field water samples from Lake Erie, Michigan and St. Johns River, Florida were employed to evaluate the potential application of this process for the degradation of MC-LR. Results showed that the presence of both alkalinity (as 89.6-117.8 mg CaCO(3)/L) and NOM (as ∼2 to ∼9.5 mg/L TOC) contributed to a significant decrease in the destruction rate of MC-LR. However, a final concentration of MC-LR bellow the guideline value of 1 μg/L was still achievable under current experimental conditions when an initial MC-LR concentration of 2.5 μg/L was spiked into those real water samples.

Journal of Membrane Science, 1999

... Therefore, several types of membranes have been investigated in previous studies. ... Ceramic... more ... Therefore, several types of membranes have been investigated in previous studies. ... Ceramic MBRs have also been tested in the treatment of municipal wastewater. A semi-industrial aerobicpilot-scale MBR, using ceramic tubular membranes was employed to treat municipal ...

Industrial & Engineering Chemistry Research, 2013

Innovative sol−gel synthesis based on the self-assembling template method has been applied to syn... more Innovative sol−gel synthesis based on the self-assembling template method has been applied to synthesize mesoporous anion-doped TiO 2 with N−F, S and C atoms using suitable surfactants and reagents, to improve simultaneously the structural, morphological, and electronic properties of TiO 2 nanomaterials and achieve anion doping of titania with high visible light photoinduced reactivity. The incorporation of anion species in the titania structure resulted in the effective extension of TiO 2 optical absorption in the visible range through the formation of intragap energy states. The anion-doped titania materials immobilized in the form of nanostructured thin films on glass substrates exhibited high photocatalytic efficiency for the degradation of the microcystin-LR (MC-LR) cyanotoxin, a hazardous water pollutant of emerging concern, under visible light irradiation. The development of these visible light-activated nanocatalysts has the potential of providing environmentally benign routes for water treatment.

Environmental Science & Technology, 2013

Kinetics of the oxidation of tryptophan (Trp) and kynurenine (Kyn), precursors of nitrogenous dis... more Kinetics of the oxidation of tryptophan (Trp) and kynurenine (Kyn), precursors of nitrogenous disinfection byproducts (N-DBP), by ferrate(VI) (Fe VI O 4 2− , Fe(VI)) were investigated over the acidic to basic pH range. The secondorder rate constants decreased with increase in pH, which could be described by the speciation of Fe(VI) and Trp (or Kyn). The trend of pH dependence of rates for Trp (i.e., aromatic α-amino acid) differs from that for glycine (i.e., aliphatic α-amino acid). A nonlinear relationship between transformation of Trp and the added amount of Fe(VI) was found. This suggests that the formed intermediate oxidized products (OPs), identified by LC-PDA and LC-MS techniques, could possibly compete with Trp to react with Fe(VI). N-Formylkynurenine (NFK) at pH 7.0 and 4-hydroxyquinoline (4-OH Q) and kynurenic acid (Kyn-A) at pH 9.0 were the major OPs. Tryptophan radical formation during the reaction was confirmed by the rapid-freeze quench EPR experiments. The oxygen atom transfer from Fe(VI) to NFK was demonstrated by reacting Fe 18 O 4 2− ion with Trp. A proposed mechanism explains the identified OPs at both neutral and alkaline pH. Kinetics and OPs by Fe(VI) were compared with other oxidants (chlorine, ClO 2

Applied Catalysis B: Environmental, 2012

This article appeared in a journal published by Elsevier. The attached copy is furnished to the a... more This article appeared in a journal published by Elsevier. The attached copy is furnished to the author for internal non-commercial research and education use, including for instruction at the authors institution and sharing with colleagues. Other uses, including reproduction and distribution, or selling or licensing copies, or posting to personal, institutional or third party websites are prohibited. In most cases authors are permitted to post their version of the article (e.g. in Word or Tex form) to their personal website or institutional repository. Authors requiring further information regarding Elsevier's archiving and manuscript policies are encouraged to visit:

Anti-Cancer Agents in Medicinal Chemistry, 2011

Microcystins are cyclic heptapeptide toxins produced by a number of genera of cyanobacteria. They... more Microcystins are cyclic heptapeptide toxins produced by a number of genera of cyanobacteria. They are ubiquitous in bodies of water worldwide and pose significant hazard to human, plant, and animal health. Microcystins are primarily hepatotoxins known to inhibit serine-threonine phosphatases leading to the disruption of cascade of events important in the regulation and control of cellular processes. Covalent binding of microcystins with phosphatases is thought to be responsible for the cytotoxic and genotoxic effects of microcystins. In addition, microcystins can trigger oxidative stress in cells resulting in necrosis or apoptosis. Their cyclic structure and novel amino acids enhance their stability and persistence in the environment. Humans are primarily exposed to microcystins via drinking water consumption and accidental ingestion of recreational water. Recreational exposure by skin contact or inhalation to microcystins is now recognized to cause a wide range of acute illnesses which can be life-threatening. Microcystins are primarily degraded by microorganisms in the environment, while sunlight can cause the isomerization of the double bonds and hydroxylation in the presence of pigments. Attempts to utilize these organisms in sand and membrane filters to treat water contaminated with microcystins showed complete removal and detoxification. Conventional water treatment processes may not fully eliminate microcystins when there are high levels of organic compounds especially during harmful bloom events. Combination of conventional and advanced oxidation technologies can potentially remove 100% of microcystins in water even in turbid conditions. This review covers selected treatment technologies to degrade microcystins in water.

Science of The Total Environment, 2009

Literature reviews examining the relationship between exposure to carbon nanofibers (CNFs) and he... more Literature reviews examining the relationship between exposure to carbon nanofibers (CNFs) and health consequences are qualitative in nature and do not employ an evidence-based assessment. This research deals with a systematic review, critical appraisal, and meta-analysis designed to examine the potential health effects associated with exposure to CNFs. The utilization of research findings into practice is also explored. Published articles were obtained from a search of electronic databases and bibliographies of identified articles. A critical appraisal was conducted using an 'Experimental Appraisal Instrument' developed in this study. The meta-analysis was established using statistical techniques with/without the incorporation of overall study quality. The likelihood of utilizing research findings into practice (i.e., from research to practice) was computed using a four-step algorithm based on the criteria of: strength of association, consistency among studies, temporality, biological gradient, type of experimental unit, type of CNF (single- and multi-wall nanotubes), CNF grade (commercial or altered), exposure dose, exposure duration, and support by analogy from the published literature. Twenty-one experimental studies satisfied the inclusion criteria and were performed on human cells, experimental animal models and animal cells as experimental units. The methodological qualities of published studies ranged from 'very poor' to 'excellent', with 'overall study description' scoring 'good' and 'study execution' equal to 'moderate'. The random-effects model was applied in the meta-analysis calculations as heterogeneity was significant at the 10% for all outcomes reported. The mean standardized meta-estimates for the experimental groups were significantly lower than those for the control groups for cell viability and cell death, respectively. Incorporating the effect of overall study quality score widened the gap between the experimental and control groups. Assessment of research findings on the basis of the four-step algorithm revealed that the likelihood of the results to occur in practice is 'somewhat possible' at this time. That is, if exposure conditions to CNF in the reported studies are similar to those in nano-manufacturing plants, it is somewhat possible that CNFs alter the function of human cells resulting in loss of cell viability and cell death. Our findings suggest that it is 'somewhat possible' for the CNF to penetrate the human cells in the targeted organs and to cause cellular damage. Although the weight of evidence is not sufficient, it is advisable that actions be taken to ensure the protection of workers exposed to CNFs, that is, (a) engineering controls should be established to contain exposure to CNF, and (b) simultaneously rigorous personnel protective equipment should be planned to further minimize the risk of CNF exposure.

Journal of Hazardous Materials

Environmental Science: Nano

Considerable attention has been paid to water treatment using nanomaterials. In this study, ethyl... more Considerable attention has been paid to water treatment using nanomaterials. In this study, ethylene glycol (EG) is used to control the formation of α-FeOOH/reduced graphene oxide (RGO) hydrogels in a...

Water Environment Research

It is postulated in this research that the paradox of “advances in technology and managemen... more It is postulated in this research that the paradox of “advances in technology and management not keeping pace with the ever-increasing urban problems” is due to the poor understanding of person-focused governance of societal, environmental and economic entities. Therefore, the objective of this paper is to present an adaptive institutional model of person-driven effectiveness and ineffectiveness. The model proposes that human, ecologic and economic outcomes are heavily influenced by a complex system of systems, spanning from individually unique “non-physical influencers” to a broader set of social and environmental influencers that have a common impact on the larger society-environment-economy (SEE) system. At the heart of the model is an analytic formulation that explains the phenomena of non-physical blocker, enhancer and indifferent that are responsible for the adaptation and maladaptation of social agents, and accordingly for the sustainability and unsust...

Nanoscale, 2016

Owing to their atomically thin structure, large surface area and mechanical strength, 2D nanoporo... more Owing to their atomically thin structure, large surface area and mechanical strength, 2D nanoporous materials are considered to be suitable alternatives for existing desalination and water purification membrane materials.

Catal. Sci. Technol., 2015

Copper oxide supported on nanoporous activated carbon (CuO-NPAC) is reported for the aqueous phas... more Copper oxide supported on nanoporous activated carbon (CuO-NPAC) is reported for the aqueous phase catalytic degradation of cyanotoxin microcystin-LR (MC-LR).

RSC Adv., 2015

Novel green synthesized zero valent iron (ZVI) nanoparticles of distinct mass fractions of 0.5, 1... more Novel green synthesized zero valent iron (ZVI) nanoparticles of distinct mass fractions of 0.5, 1.5 and 2.5 wt% are blended with cellulose acetate (CA) to prepare CA/ZVI mixed matrix membranes (MMMs).

Environmental Chemistry Letters, 2022

Research on plastic pollution has recently evidenced the ubiquitous presence of tiny plastic part... more Research on plastic pollution has recently evidenced the ubiquitous presence of tiny plastic particles called microplastics. Microplastics alter organisms because microplastics tend to bioaccumulate, they contain hazardous additives, and they carry other contaminants and pathogens adsorbed on their surface. Here, we review the biodegradation of the five most common microplastics: polyethylene, polypropylene, polyvinyl chloride, polyethylene terephthalate, and polystyrene. Despite the fact that most plastics are hardly biodegradable, biodegradation is still a popular remediation techniques because it is highly economical and environmentally friendly. Biodegradation can be done applying single or combined bio-cultures such as bacteria, mold, yeast, and algae. We present analytical and microbiological methods used for monitoring microplastic biodegradation. Actually, no microbial method removes completely microplastics from the environment within a reasonable time interval. As a consequence, the last developments combine biodegradation with other methods such as membrane filtration.

Cost metrics can include levelized costs of water treatment as well as individual cost components... more Cost metrics can include levelized costs of water treatment as well as individual cost components, such capital or operations and maintenance (O&M) costs. Energy Performance Energy performance metrics can include the total energy requirements of the water treatment process, the type of energy required (e.g., thermal vs. electricity), embedded energy in chemicals and materials, and the degree to which alternative energy resources are utilized. Water Treatment Performance Water treatment performance metrics can include the percent removal of various contaminants of concern and the percent recovery of water from the treatment train. Human Health and Environment Externalities Externality metrics can include air emissions, greenhouse gas emissions, waste streams, societal and health impacts, land-use impacts. Process Adaptability Process adaptability metrics can include the ability to incorporate variable input water qualities, the ability to incorporate variable input water quantity flows, the ability to produce variable output water quality, and the ability to operate flexibly in response to variable energy inputs.

I n t r o d u c t I o n Clean water is critical to ensure good health, strong communities, vibran... more I n t r o d u c t I o n Clean water is critical to ensure good health, strong communities, vibrant ecosystems, and a functional economy for manufacturing, farming, tourism, recreation, energy production, and other sectors' needs. Research to improve desalination technologies can make nontraditional sources of water (i.e., brackish water; seawater; produced and extracted water; and power sector, industrial, municipal, and agricultural wastewaters) a cost-effective alternative. These nontraditional sources can then be applied to a variety of beneficial end uses, such as drinking water, industrial process water, and irrigation, expanding the circular water economy by reusing water supplies and valorizing constituents we currently consider to be waste. As an added benefit, these water supplies could contain valuable constituents that could be reclaimed to further a circular economy. I n t r o d u c t I o n 1.2. Pipe-Parity and Baseline Definitions A core part of NAWI's vision of a circular water economy is reducing the cost of treating nontraditional source waters to the same range as the portfolio of accessing new traditional water sources, essentially achieving pipe-parity. The costs considered are not just economic but include consideration of energy consumption, system reliability, water recovery, and other qualitative factors that affect the selection of a new water source. To effectively assess R&D opportunities, pipeparity metrics are utilized; they encompass a variety of information that is useful to decision makers regarding investments related to different source water types. Pipe-parity is defined as technological and non-technological solutions and capabilities that make marginal water sources viable for end-use applications. Like the concept of grid parity (where an alternative energy source generates power at a levelized cost of electricity [LCOE] that is less than or equal to the price of power from the electricity grid), a nontraditional water source achieves pipe-parity when a decision maker chooses it as their best option for extending its water supply. Specific pipe-parity metrics of relevance can include: Cost Cost metrics can include levelized costs of water treatment as well as individual cost components, such as capital or operational and maintenance (O&M) costs. Energy Performance Energy performance metrics can include the total energy requirements of the water treatment process, the type of energy required (e.g., thermal vs. electricity), embedded energy in chemicals and materials, and the degree to which alternative energy resources are utilized. Water Treatment Performance Water treatment performance metrics can include the percent removal of various constituents of concern and the percent recovery of water from the treatment train. Human Health and Environment Externalities Externality metrics can include air emissions, greenhouse gas emissions, waste streams, societal and health impacts, and land-use impacts. Process Adaptability Process adaptability metrics can include the ability to incorporate variable input water qualities, incorporate variable input water quantity flows, produce variable output water quality, and operate flexibly in response to variable energy inputs. I n t r o d u c t I o n Seawater and Ocean Water Water from the ocean or from bodies strongly influenced by ocean water, including bays and estuaries, with a typical total dissolved solids (TDS) between 30,000 and 35,000 milligrams per liter (mg/L). Brackish Groundwater Water pumped from brackish aquifers, with particular focus on inland areas where brine disposal is limiting. Brackish water generally is defined as water with 1-10 grams per liter (g/L) of total dissolved solids (TDS). Industrial Wastewater Water from various industrial processes that can be treated for reused Municipal Wastewater Wastewater treated for reuse through municipal resource recovery treatment plants utilizing advanced treatment processes or decentralized treatment systems Agricultural Wastewater Wastewater from tile drainage, tailwater, and other water produced on irrigated croplands, as well as wastewater generated during livestock management, that can be treated for reuse or disposal Mining Wastewater Wastewater from mining operations that can be reused or prepared for disposal Produced Water Water used for or produced by oil and gas exploration activities (including fracking) that can be reused or prepared for disposal Power and Cooling Wastewater Water used for cooling or as a byproduct of treatment (e.g., flue gas desulfurization) that can be reused or prepared for disposal These nontraditional water sources range widely in TDS (100 milligrams per liter [mg/L]-800,000 mg/L total) as well as the type and concentrations of contaminants (e.g., nutrients, hydrocarbons, organic compounds, metals). These different water supplies require varying degrees of treatment to reach reusable quality.

Water Research, 2016

Visible light (VIS) photocatalysis has large potential as a sustainable water treatment process, ... more Visible light (VIS) photocatalysis has large potential as a sustainable water treatment process, however the reaction pathways and degradation processes of organic pollutants are not yet clearly defined. The presence of cyanobacteria cause water quality problems since several genera can produce potent cyanotoxins, harmful to human health. In addition, cyanobacteria produce taste and odor compounds, which pose serious aesthetic problems in drinking water. Although photocatalytic degradation of cyanotoxins and taste and odor compounds have been reported under UV-A light in the presence of TiO 2 , limited studies have been reported on their degradation pathways by VIS photocatalysis of these problematic compounds. The main objectives of this work were to study the VIS photocatalytic degradation process, define the reactive oxygen species (ROS) involved and elucidate the reaction mechanisms. We report carbon doped TiO 2 (C-TiO 2) under VIS leads to the slow degradation of cyanotoxins, microcystin-LR (MC-LR) and cylindrospermopsin (CYN), while taste and odor compounds, geosmin and 2-methylisoborneol, were not appreciably degraded. Further studies were carried-out employing several specific radical scavengers (potassium bromide, isopropyl alcohol, sodium azide, superoxide dismutase and catalase) and probes (coumarin) to assess the role of different ROS (hydroxyl radical • OH, singlet oxygen 1 O 2 , superoxide radical anion O 2 •−) in the degradation processes. Reaction pathways of MC-LR and CYN were defined through identification and monitoring of intermediates using liquid chromatography tandem mass spectrometry (LC-MS/MS) for VIS in comparison with UV-A photocatalytic treatment. The effects of scavengers and probes on the degradation process under VIS, as well as the differences in product distributions under VIS and UV-A, suggested that the main species in VIS photocatalysis is O 2 •− , with • OH and 1 O 2 playing minor roles in the degradation.

Journal of Hazardous Materials, 2015

h i g h l i g h t s • UV-254 nm/H 2 O 2 AOP was utilized for the degradation and mineralization o... more h i g h l i g h t s • UV-254 nm/H 2 O 2 AOP was utilized for the degradation and mineralization of PBSA and BSA. • Promotion of k obs with [H 2 O 2 ] 0 ≤ 4 mM and inhibition at higher [H 2 O 2 ] 0 were observed. • The S and N were released and monitored as SO 4 2− and NH 4 + , respectively. • Br − inhibited both the degradation and mineralization much more significantly than Cl − .

RSC Adv., 2015

Granular activated carbon (GAC) particles can be shaped into an integrated 3D-anode using PVDF bi... more Granular activated carbon (GAC) particles can be shaped into an integrated 3D-anode using PVDF binder and electro oxidation of reactive dyes in a three-dimensional flow-through carbon anode reactor (TDFCR) delivers a clean effluent free from carbon dust.

Water Research, 2012

The destruction of the commonly found cyanobacterial toxin, microcystin-LR (MC-LR), in surface wa... more The destruction of the commonly found cyanobacterial toxin, microcystin-LR (MC-LR), in surface waters by UV-C/H(2)O(2) advanced oxidation process (AOP) was studied. Experiments were carried out in a bench scale photochemical apparatus with low pressure mercury vapor germicidal lamps emitting at 253.7 nm. The degradation of MC-LR was a function of UV fluence. A 93.9% removal with an initial MC-LR concentration of 1 μM was achieved with a UV fluence of 80 mJ/cm(2) and an initial H(2)O(2) concentration of 882 μM. When increasing the concentration of MC-LR only, the UV fluence-based pseudo-first order reaction rate constant generally decreased, which was probably due to the competition between by-products and MC-LR for hydroxyl radicals. An increase in H(2)O(2) concentration led to higher removal efficiency; however, the effect of HO scavenging by H(2)O(2) became significant for high H(2)O(2) concentrations. The impact of water quality parameters, such as pH, alkalinity and the presence of natural organic matter (NOM), was also studied. Field water samples from Lake Erie, Michigan and St. Johns River, Florida were employed to evaluate the potential application of this process for the degradation of MC-LR. Results showed that the presence of both alkalinity (as 89.6-117.8 mg CaCO(3)/L) and NOM (as ∼2 to ∼9.5 mg/L TOC) contributed to a significant decrease in the destruction rate of MC-LR. However, a final concentration of MC-LR bellow the guideline value of 1 μg/L was still achievable under current experimental conditions when an initial MC-LR concentration of 2.5 μg/L was spiked into those real water samples.

Journal of Membrane Science, 1999

... Therefore, several types of membranes have been investigated in previous studies. ... Ceramic... more ... Therefore, several types of membranes have been investigated in previous studies. ... Ceramic MBRs have also been tested in the treatment of municipal wastewater. A semi-industrial aerobicpilot-scale MBR, using ceramic tubular membranes was employed to treat municipal ...

Industrial & Engineering Chemistry Research, 2013

Innovative sol−gel synthesis based on the self-assembling template method has been applied to syn... more Innovative sol−gel synthesis based on the self-assembling template method has been applied to synthesize mesoporous anion-doped TiO 2 with N−F, S and C atoms using suitable surfactants and reagents, to improve simultaneously the structural, morphological, and electronic properties of TiO 2 nanomaterials and achieve anion doping of titania with high visible light photoinduced reactivity. The incorporation of anion species in the titania structure resulted in the effective extension of TiO 2 optical absorption in the visible range through the formation of intragap energy states. The anion-doped titania materials immobilized in the form of nanostructured thin films on glass substrates exhibited high photocatalytic efficiency for the degradation of the microcystin-LR (MC-LR) cyanotoxin, a hazardous water pollutant of emerging concern, under visible light irradiation. The development of these visible light-activated nanocatalysts has the potential of providing environmentally benign routes for water treatment.

Environmental Science & Technology, 2013

Kinetics of the oxidation of tryptophan (Trp) and kynurenine (Kyn), precursors of nitrogenous dis... more Kinetics of the oxidation of tryptophan (Trp) and kynurenine (Kyn), precursors of nitrogenous disinfection byproducts (N-DBP), by ferrate(VI) (Fe VI O 4 2− , Fe(VI)) were investigated over the acidic to basic pH range. The secondorder rate constants decreased with increase in pH, which could be described by the speciation of Fe(VI) and Trp (or Kyn). The trend of pH dependence of rates for Trp (i.e., aromatic α-amino acid) differs from that for glycine (i.e., aliphatic α-amino acid). A nonlinear relationship between transformation of Trp and the added amount of Fe(VI) was found. This suggests that the formed intermediate oxidized products (OPs), identified by LC-PDA and LC-MS techniques, could possibly compete with Trp to react with Fe(VI). N-Formylkynurenine (NFK) at pH 7.0 and 4-hydroxyquinoline (4-OH Q) and kynurenic acid (Kyn-A) at pH 9.0 were the major OPs. Tryptophan radical formation during the reaction was confirmed by the rapid-freeze quench EPR experiments. The oxygen atom transfer from Fe(VI) to NFK was demonstrated by reacting Fe 18 O 4 2− ion with Trp. A proposed mechanism explains the identified OPs at both neutral and alkaline pH. Kinetics and OPs by Fe(VI) were compared with other oxidants (chlorine, ClO 2

Applied Catalysis B: Environmental, 2012

This article appeared in a journal published by Elsevier. The attached copy is furnished to the a... more This article appeared in a journal published by Elsevier. The attached copy is furnished to the author for internal non-commercial research and education use, including for instruction at the authors institution and sharing with colleagues. Other uses, including reproduction and distribution, or selling or licensing copies, or posting to personal, institutional or third party websites are prohibited. In most cases authors are permitted to post their version of the article (e.g. in Word or Tex form) to their personal website or institutional repository. Authors requiring further information regarding Elsevier's archiving and manuscript policies are encouraged to visit:

Anti-Cancer Agents in Medicinal Chemistry, 2011

Microcystins are cyclic heptapeptide toxins produced by a number of genera of cyanobacteria. They... more Microcystins are cyclic heptapeptide toxins produced by a number of genera of cyanobacteria. They are ubiquitous in bodies of water worldwide and pose significant hazard to human, plant, and animal health. Microcystins are primarily hepatotoxins known to inhibit serine-threonine phosphatases leading to the disruption of cascade of events important in the regulation and control of cellular processes. Covalent binding of microcystins with phosphatases is thought to be responsible for the cytotoxic and genotoxic effects of microcystins. In addition, microcystins can trigger oxidative stress in cells resulting in necrosis or apoptosis. Their cyclic structure and novel amino acids enhance their stability and persistence in the environment. Humans are primarily exposed to microcystins via drinking water consumption and accidental ingestion of recreational water. Recreational exposure by skin contact or inhalation to microcystins is now recognized to cause a wide range of acute illnesses which can be life-threatening. Microcystins are primarily degraded by microorganisms in the environment, while sunlight can cause the isomerization of the double bonds and hydroxylation in the presence of pigments. Attempts to utilize these organisms in sand and membrane filters to treat water contaminated with microcystins showed complete removal and detoxification. Conventional water treatment processes may not fully eliminate microcystins when there are high levels of organic compounds especially during harmful bloom events. Combination of conventional and advanced oxidation technologies can potentially remove 100% of microcystins in water even in turbid conditions. This review covers selected treatment technologies to degrade microcystins in water.

Science of The Total Environment, 2009

Literature reviews examining the relationship between exposure to carbon nanofibers (CNFs) and he... more Literature reviews examining the relationship between exposure to carbon nanofibers (CNFs) and health consequences are qualitative in nature and do not employ an evidence-based assessment. This research deals with a systematic review, critical appraisal, and meta-analysis designed to examine the potential health effects associated with exposure to CNFs. The utilization of research findings into practice is also explored. Published articles were obtained from a search of electronic databases and bibliographies of identified articles. A critical appraisal was conducted using an 'Experimental Appraisal Instrument' developed in this study. The meta-analysis was established using statistical techniques with/without the incorporation of overall study quality. The likelihood of utilizing research findings into practice (i.e., from research to practice) was computed using a four-step algorithm based on the criteria of: strength of association, consistency among studies, temporality, biological gradient, type of experimental unit, type of CNF (single- and multi-wall nanotubes), CNF grade (commercial or altered), exposure dose, exposure duration, and support by analogy from the published literature. Twenty-one experimental studies satisfied the inclusion criteria and were performed on human cells, experimental animal models and animal cells as experimental units. The methodological qualities of published studies ranged from 'very poor' to 'excellent', with 'overall study description' scoring 'good' and 'study execution' equal to 'moderate'. The random-effects model was applied in the meta-analysis calculations as heterogeneity was significant at the 10% for all outcomes reported. The mean standardized meta-estimates for the experimental groups were significantly lower than those for the control groups for cell viability and cell death, respectively. Incorporating the effect of overall study quality score widened the gap between the experimental and control groups. Assessment of research findings on the basis of the four-step algorithm revealed that the likelihood of the results to occur in practice is 'somewhat possible' at this time. That is, if exposure conditions to CNF in the reported studies are similar to those in nano-manufacturing plants, it is somewhat possible that CNFs alter the function of human cells resulting in loss of cell viability and cell death. Our findings suggest that it is 'somewhat possible' for the CNF to penetrate the human cells in the targeted organs and to cause cellular damage. Although the weight of evidence is not sufficient, it is advisable that actions be taken to ensure the protection of workers exposed to CNFs, that is, (a) engineering controls should be established to contain exposure to CNF, and (b) simultaneously rigorous personnel protective equipment should be planned to further minimize the risk of CNF exposure.

Journal of Hazardous Materials

Environmental Science: Nano

Considerable attention has been paid to water treatment using nanomaterials. In this study, ethyl... more Considerable attention has been paid to water treatment using nanomaterials. In this study, ethylene glycol (EG) is used to control the formation of α-FeOOH/reduced graphene oxide (RGO) hydrogels in a...

Water Environment Research

It is postulated in this research that the paradox of “advances in technology and managemen... more It is postulated in this research that the paradox of “advances in technology and management not keeping pace with the ever-increasing urban problems” is due to the poor understanding of person-focused governance of societal, environmental and economic entities. Therefore, the objective of this paper is to present an adaptive institutional model of person-driven effectiveness and ineffectiveness. The model proposes that human, ecologic and economic outcomes are heavily influenced by a complex system of systems, spanning from individually unique “non-physical influencers” to a broader set of social and environmental influencers that have a common impact on the larger society-environment-economy (SEE) system. At the heart of the model is an analytic formulation that explains the phenomena of non-physical blocker, enhancer and indifferent that are responsible for the adaptation and maladaptation of social agents, and accordingly for the sustainability and unsust...

Nanoscale, 2016

Owing to their atomically thin structure, large surface area and mechanical strength, 2D nanoporo... more Owing to their atomically thin structure, large surface area and mechanical strength, 2D nanoporous materials are considered to be suitable alternatives for existing desalination and water purification membrane materials.

Catal. Sci. Technol., 2015

Copper oxide supported on nanoporous activated carbon (CuO-NPAC) is reported for the aqueous phas... more Copper oxide supported on nanoporous activated carbon (CuO-NPAC) is reported for the aqueous phase catalytic degradation of cyanotoxin microcystin-LR (MC-LR).

RSC Adv., 2015

Novel green synthesized zero valent iron (ZVI) nanoparticles of distinct mass fractions of 0.5, 1... more Novel green synthesized zero valent iron (ZVI) nanoparticles of distinct mass fractions of 0.5, 1.5 and 2.5 wt% are blended with cellulose acetate (CA) to prepare CA/ZVI mixed matrix membranes (MMMs).

Water is the most crucial material for human survival, after air. Without water, life would not b... more Water is the most crucial material for human survival, after air. Without water, life would not be possible. It is important to know how much water is available to us and how much water is polluted. We need to monitor pollutants vigorously, both at point and non-point sources, using advanced analytical techniques that can monitor ultra trace
amounts of contaminants. Water reclamation is an absolute necessity today because we have contaminated our surface water, and even groundwater in some cases, to a point that it is not clean enough for drinking or cooking. Most importantly, we have to use water judiciously and reclaim water that is contaminated. This book provides information on various global water challenges and solutions.
We face many water challenges in terms of availability, quality, and sustainability (Chapter 1). There is an urgent need to find ways to make water more sustainable. To achieve this objective, we will have to address scientific, technical, economic, and
social issues. Chapters 2 and 3 raise our awareness of water issues, as well as the impact of climate change. Water challenges, including sanitation issues in Central America, South America, and Africa, are covered in Chapters 4, 5, and 6. Water pollution in various rivers in India is encompassed in Chapters 7, 8, and 9. The currently implemented solutions are discussed in some detail. Water scarcity in the Middle East provides an interesting study in that part of the world (Chapter 10). The impact of firefighting foams on water in Japan is discussed at some length in Chapter 11. Overcoming the water treatment challenges in various European countries is covered in Chapters 12, 13, and 14.
Chapter 15 discusses the role of immobilized microorganisms and aggregates in wastewater treatment. Reducing the effect of drought on soil in northeast Brazil is covered in Chapter 16. Promoting biodiversity through the maintenance of healthy wetlands can provide beneficial and sustainable ecosystems; however, it can also have adverse consequences on human health (see Chapter 17 for a study in Australia). Nanotechnology solutions to global water challenges are provided in Chapter 18. As a result of their exceptional adsorptive capacity for water contaminants, grapheme based nanomaterials have emerged as a subject of significant importance in the area of membrane filtration and water treatment. Global fresh water is finite, and its supply
is severely strained by competing forces of an expanding world population on the one hand, and alterations in the water cycle as a result of climate change on the other (Chapter 19).