A5069575097- Graphene research and applications
- Fullerene Chemistry and Applications
- Graphene and Nanomaterials Applications
- Nanoparticles: synthesis and applications
- Iron oxide chemistry and applications
- Membrane Separation Technologies
- Environmental remediation with nanomaterials
- Radioactive element chemistry and processing
- Advanced Photocatalysis Techniques
- Gas Sensing Nanomaterials and Sensors
- Per- and polyfluoroalkyl substances research
- Carbon Nanotubes in Composites
- Polymer Nanocomposite Synthesis and Irradiation
- Nanoparticle-Based Drug Delivery
- Membrane Separation and Gas Transport
- Gold and Silver Nanoparticles Synthesis and Applications
- Nanomaterials for catalytic reactions
- Extraction and Separation Processes
- Adsorption and biosorption for pollutant removal
- Electrochemical Analysis and Applications
- Advanced Nanomaterials in Catalysis
- Geochemistry and Elemental Analysis
- Groundwater flow and contamination studies
- Atmospheric and Environmental Gas Dynamics
- Analytical Chemistry and Sensors
Yale University
2019-2025
Systems Engineering Research Center
2020-2024
University of Missouri
2023
University of New Haven
2020-2021
Washington University in St. Louis
2011-2020
Rice University
2003-2012
ETH Zurich
2011
Nankai University
2010
U.S. Army Engineer Research and Development Center
2010
United States Army
2010
We show that the cytotoxicity of water-soluble fullerene species is a sensitive function surface derivatization; in two different human cell lines, lethal dose changed over 7 orders magnitude with relatively minor alterations structure. In particular, an aggregated form C60, least derivatized four materials, was substantially more toxic than highly soluble derivatives such as C3, Na+2-3[C60O7-9(OH)12-15](2-3)-, and C60(OH)24. Oxidative damage to membranes observed all cases where exposure...
This study investigates the aqueous stability of multi-walled carbon nanotubes (MWNTs) in presence natural organic matter (NOM). MWNTs were readily dispersed as an suspension both model NOM (Suwannee River (SR-NOM)) solutions and surface water (actual Suwannee with unaltered background), which remained stable for over 1 month. Microscopic analyses suggested that consisted primarily individually MWNTs. Concentrations suspended phase, quantified using thermal optical transmittance analysis...
Upon contact with water, under a variety of conditions, C60 spontaneously forms stable aggregate nanoscale dimensions (d = 25−500 nm), termed here "nano-C60". The color, hydrophobicity, and reactivity individual are substantially altered in this form. Herein, we provide conclusive lines evidence demonstrating that solution these aggregates crystalline order remain as underivatized throughout the formation/stabilization process can later be chemically reversed. Particle size affected by...
State-of-the-art desalination membranes exhibit high water-salt selectivity, but their ability to discriminate between ions is limited. Elucidating the fundamental mechanisms underlying ion transport and selectivity in subnanometer pores therefore imperative for development of ion-selective membranes. Here, we compare overall energy barrier salt barriers individual transport, showing that cations anions traverse membrane pore an independent manner. Supported by density functional theory...
Prior to the implementation of any new technology, possible environmental and health repercussions first must be researched. Fullerenes are produced soon on an industrial scale, with applications quickly following. To investigate impact fullerenes, a C60-water suspension (nano-C60) was synthesized then evaluated for cell-association toxicity, using bacteria Escherichia coli Bacillus subtilis as indicator species. In defined low-salts medium, nano-C60 associated both Gram-negative E....
Experimental and mathematical modeling studies were performed to investigate the transport retention of nanoscale fullerene aggregates (nC60) in water-saturated porous media. Aqueous suspensions nC60 (95 nm diameter, 1 3 mg/L) introduced into columns packed with either glass beads or Ottawa sand at a Darcy velocity 2.8 m/d. In presence 1.0 mM CaCl2, effluent breakthrough curves (BTCs) gradually increased maximum value then declined sharply upon reintroduction nC60-free solution. Retention...
The objective of this study was to investigate photochemical production singlet oxygen (1O2) and superoxide radical anion (O2•-) by C60 in water. It demonstrated that photoexcited the aqueous phase efficiently mediated transfer absorbed energy produced when associated with surfactant (Triton X100 Brij 78) or polymer (polyvinylpyrrolidone), which is consistent previously observed behavior organic solvents. However, present as colloidal aggregate suspension, prepared through solvent exchange...
The important role of natural organic matter (NOM)-Fe colloids in influencing contaminant transport, and this can be influenced by the formation, aggregation, particle deposition dynamics NOM-Fe colloids. In work, at different C/Fe ratios were prepared mixing concentrations humic acid (HA) with 10 mg/L Fe(II) under anoxic conditions. characterized an array techniques their aggregation behaviors examined both oxic are composed HA-Fe(II) conditions, while they made up HA-Fe(III) conditions...
In this work, we describe multifunctional, crumpled graphene oxide (CGO) porous nanocomposites that are assembled as advanced, reactive water treatment membranes. Crumpled 3D based materials fundamentally differ from 2D flat analogues in they highly aggregation and compression-resistant (i.e., π–π stacking resistant) allow for the incorporation (wrapping) of other, multifunctional particles inside 3D, composite structure. Here, assemblies nanoscale, monomeric CGO with encapsulated (as a...
Aqueous aggregation processes can significantly impact function, effective toxicity, environmental transport, and ultimate fate of advanced nanoscale materials, including graphene oxide (GO). In this work, we have synthesized flat (GO) five physically crumpled GOs (CGO, with different degrees thermal reduction, thus oxygen functionality) using an aerosol method, characterized the evolution surface chemistry morphology a suite spectroscopic (UV–vis, FTIR, XPS) microscopic (AFM, SEM, TEM)...
A useful feedback loop: insights from theoretical calculations are used for rational design of nanosensors and elucidating surface interactions.
Natural organic matter-iron (NOM-Fe) colloids are ubiquitous at anoxic–oxic interfaces of subsurface environments. Fe(II) or NOM can chemically reduce Cr(VI) to Cr(III), and the formation Cr(III)-NOM-Fe control fate transport Cr. We explored Cr(III)-humic acid (HA)-Fe upon reaction with HA-Fe(II) over a range environmentally relevant conditions. was completely reduced by complexes under anoxic conditions, Cr(III)-HA-Fe depended on HA concentration (or molar C/Fe ratio) redox No formed...
We describe how the reduction of graphene oxide (GO) via environmentally relevant pathways affects its transport behavior in porous media. A pair sulfide-reduced GOs (RGOs), prepared by reducing 10 mg/L GO with 0.1 mM Na2S for 3 and 5 days, respectively, exhibited lower mobility than did parent saturated quartz sand. Interestingly, decreased cannot simply be attributed to increased hydrophobicity aggregation upon because retention mechanisms RGOs were highly cation-dependent. In presence Na+...
Surface-functionalized magnetic nanoparticles are promising adsorbents due to their large surface areas and ease of separation after contaminant removal. In this work, the affinity Cr(VI) adsorption 8 nm surface-functionalized superparamagnetic magnetite was determined for coatings with amine (trimethyloctadecylammonium bromide, CTAB) carboxyl (stearic acid, SA) functional groups. adsorbed more strongly CTAB-coated than SA-coated materials electrostatic interactions between positively...
Photocatalysis provides a route to convert methane into an energy-dense, liquid fuel, such as methanol, using only natural gas, sunlight, water (or oxygen), and the catalyst. In this report, we compare photocatalytic activity selectivity for bismuth vanadate (BiVO4) microcrystals with different morphologies partially oxidize methanol. Bipyramidal BiVO4 comprising {102} {012} surface facets were found be both more active selective methanol conversion compared platelet that expose {001} their...
Graphene oxide (GO) materials have demonstrated considerable potential in next-generation water treatment membrane-based technologies, which include antimicrobial applications. GO properties can be further enhanced by preloading or chemically generating surface-associated nanoscale silver particles (nAg). However, for these systems, functionality decreases over time as a function of Ag mass loss via dissolution (as Ag+). In this work, we demonstrate facile photocatalytic situ synthesis nAg...