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Pedro J. J. Alvarez

Bio: Pedro J. J. Alvarez is an academic researcher from Rice University. The author has contributed to research in topics: Bioremediation & Medicine. The author has an hindex of 89, co-authored 378 publications receiving 34837 citations. Previous affiliations of Pedro J. J. Alvarez include University of Minnesota & University of Michigan.


Papers
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TL;DR: This review critiques existing nanomaterial research in freshwater, marine, and soil environments and illustrates the paucity of existing research and demonstrates the need for additional research.
Abstract: The recent advances in nanotechnology and the corresponding increase in the use of nanomaterials in products in every sector of society have resulted in uncertainties regarding environmental impacts. The objectives of this review are to introduce the key aspects pertaining to nanomaterials in the environment and to discuss what is known concerning their fate, behavior, disposition, and toxicity, with a particular focus on those that make up manufactured nanomaterials. This review critiques existing nanomaterial research in freshwater, marine, and soil environments. It illustrates the paucity of existing research and demonstrates the need for additional research. Environmental scientists are encouraged to base this research on existing studies on colloidal behavior and toxicology. The need for standard reference and testing materials as well as methodology for suspension preparation and testing is also discussed.

2,566 citations

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TL;DR: The antimicrobial mechanisms of several nanoparticles are reviewed, their merits, limitations and applicability for water disinfection and biofouling control are discussed, and research needs to utilize novel nanomaterials for water treatment applications are highlighted.

2,108 citations

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TL;DR: This work suggests that AgNP morphological properties known to affect antimicrobial activity are indirect effectors that primarily influence Ag(+) release, and antibacterial activity could be controlled by modulating Ag(+ release, possibly through manipulation of oxygen availability, particle size, shape, and/or type of coating.
Abstract: For nearly a decade, researchers have debated the mechanisms by which AgNPs exert toxicity to bacteria and other organisms. The most elusive question has been whether the AgNPs exert direct “particle-specific” effects beyond the known antimicrobial activity of released silver ions (Ag+). Here, we infer that Ag+ is the definitive molecular toxicant. We rule out direct particle-specific biological effects by showing the lack of toxicity of AgNPs when synthesized and tested under strictly anaerobic conditions that preclude Ag(0) oxidation and Ag+ release. Furthermore, we demonstrate that the toxicity of various AgNPs (PEG- or PVP- coated, of three different sizes each) accurately follows the dose–response pattern of E. coli exposed to Ag+ (added as AgNO3). Surprisingly, E. coli survival was stimulated by relatively low (sublethal) concentration of all tested AgNPs and AgNO3 (at 3–8 μg/L Ag+, or 12–31% of the minimum lethal concentration (MLC)), suggesting a hormetic response that would be counterproductive t...

1,785 citations

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TL;DR: Recent development in nanotechnology for water and wastewater treatment is reviewed, covering candidate nanomaterials, properties and mechanisms that enable the applications, advantages and limitations as compared to existing processes, and barriers and research needs for commercialization.

1,744 citations

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TL;DR: The potential eco-toxicity of nanosized titanium dioxide, silicon dioxide, and zinc oxide water suspensions was investigated using Gram-positive Bacillus subtilis and Gram-negative Escherichia coli as test organisms, with antibacterial activity increasing with particle concentration.

1,406 citations


Cited by
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TL;DR: It is anticipated that this review can stimulate a new research doorway to facilitate the next generation of g-C3N4-based photocatalysts with ameliorated performances by harnessing the outstanding structural, electronic, and optical properties for the development of a sustainable future without environmental detriment.
Abstract: As a fascinating conjugated polymer, graphitic carbon nitride (g-C3N4) has become a new research hotspot and drawn broad interdisciplinary attention as a metal-free and visible-light-responsive photocatalyst in the arena of solar energy conversion and environmental remediation. This is due to its appealing electronic band structure, high physicochemical stability, and “earth-abundant” nature. This critical review summarizes a panorama of the latest progress related to the design and construction of pristine g-C3N4 and g-C3N4-based nanocomposites, including (1) nanoarchitecture design of bare g-C3N4, such as hard and soft templating approaches, supramolecular preorganization assembly, exfoliation, and template-free synthesis routes, (2) functionalization of g-C3N4 at an atomic level (elemental doping) and molecular level (copolymerization), and (3) modification of g-C3N4 with well-matched energy levels of another semiconductor or a metal as a cocatalyst to form heterojunction nanostructures. The constructi...

5,054 citations

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TL;DR: The mechanisms of generation and potential impacts of microplastics in the ocean environment are discussed, and the increasing levels of plastic pollution of the oceans are understood, it is important to better understand the impact of microPlastic in the Ocean food web.

4,706 citations

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TL;DR: In this paper, the complex mechanisms of Fenton and Fenton-like reactions and the important factors influencing these reactions, from both a fundamental and practical perspective, in applications to water and soil treatment, are discussed.
Abstract: Fenton chemistry encompasses reactions of hydrogen peroxide in the presence of iron to generate highly reactive species such as the hydroxyl radical and possibly others. In this review, the complex mechanisms of Fenton and Fenton-like reactions and the important factors influencing these reactions, from both a fundamental and practical perspective, in applications to water and soil treatment, are discussed. The review covers modified versions including the photoassisted Fenton reaction, use of chelated iron, electro-Fenton reactions, and Fenton reactions using heterogeneous catalysts. Sections are devoted to nonclassical pathways, by-products, kinetics and process modeling, experimental design methodology, soil and aquifer treatment, use of Fenton in combination with other advanced oxidation processes or biodegradation, economic comparison with other advanced oxidation processes, and case studies.

3,218 citations

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TL;DR: Due to complexity of soil-water system in nature, the effectiveness of biochars on remediation of various organic/inorganic contaminants is still uncertain.

3,163 citations

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TL;DR: The technical feasibility of various low-cost adsorbents for heavy metal removal from contaminated water has been reviewed and it is evident from the literature survey of about 100 papers that low- cost adsorbent have demonstrated outstanding removal capabilities for certain metal ions as compared to activated carbon.

3,072 citations