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.

Nanotechnology in the Environment—The Good, the Bad, and the Ugly

Abstract: Nanotechnology is the ability to work at the molecular level, atom by atom, to create larger structures with fundamentally new molecular organization, novel properties, and functions. Engineered nanomaterials, typically a tenth the size of a human cell, are currently being used for a broad range of novel applications, including drug delivery, tissue engineering, tumor treatment, imaging, catalysis, detectors/sensors, and energy storage and transmission devices. Although some nanomaterials have been synthesized since the 1980s, their widespread production is relatively recent and their market size is expected to reach $1 trillion within 10 to 15 years. Such rapid growth suggests the potential for large environmental footprints, some of which will be good, some bad, and some ugly. On the good side, some nanomaterials hold great promise for reducing waste production, cleaning up industrial contamination, providing potable water, and improving the efficacy of energy production and use. The high potential to improve environmental technologies some of which date back to the Victorian era is intrinsically related to the small size of engineered nanomaterials, which results in significantly different properties than the associated bulk materials. Small size translates into a large surface to volume ratio, which implies greater opportunity to interact with environmental pollutants. In a sense, nanomaterials are “all surface.” This can be a highly desirable property for water, wastewater, and hazardous waste treatment. Some nanomaterials can be superior adsorbents or catalysts that remove pollutants more efficiently and at a substantially lower cost than current materialintensive approaches such as ion exchange resins and activated carbon adsorption. Nanotechnology also offers the potential for multifunctional materials, such as nano-architectured membranes for water treatment that incorporate chemically reactive nanomaterials to accomplish both separation and degradation of pollutants and enhance antifouling properties. The good news is that many of our colleagues are making significant progress toward the development of environmental nanotechnologies. These include nanosized iron for reductive treatment of chlorinated solvent DNAPLs, nanomagnetite for the removal of arsenic by sorption and magnetic separation, high-performance nanoscale Pd/ Au catalysts for treating particularly challenging contaminants in water that must be removed to a very low level, and novel advanced oxidation and disinfection approaches, to name a few. We hope to publish more papers in these emerging areas of research in the near future. On the bad side, the environment will be increasingly prone to

Phenanthrene removal by Penicillium frequentans grown on a solid-state culture: effect of oxygen concentration.

Abstract: Phenanthrene removal by Penicillium frequentans was compared under aerobic and microaerophilic conditions in a solid culture amended with low quantities of an agricultural residue. An inoculum of P. frequentans grown on sugarcane bagasse pith was mixed with soil spiked with 200 mg l−1 of phenanthrene, to obtain a final bagasse/soil ratio of 1:16. The C/N ratio was adjusted to 60 and the moisture content to 40%. The oxygen concentrations were adjusted to 20%, 10%, 5%, 2% and close to 0%, in the soil-gas phase for each treatment. There were statistically significant (p<0.05) differences in the metabolic activity at different oxygen concentrations, measured as CO2 production. Phenanthrene removal rates increased with oxygen concentration, reaching 52% removal after 17 days of incubation for the treatment with 20% O2. Nevertheless, oxygen-limited (microaerophilic) conditions did not preclude phenanthrene degradation.

Detection and cell sorting of Pseudonocardia species by fluorescence in situ hybridization and flow cytometry using 16S rRNA-targeted oligonucleotide probes.

Abstract: Pseudonocardia spp. are receiving increasing attention due to their ability to biodegrade recalcitrant cyclic ether pollutants (e.g., 1,4-dioxane and tetrahydrofuran), as well as for their distinctive ecological niches (e.g., symbiosis with ants/plants and production of antibiotics). Isolating and characterizing Pseudonocardia spp. is thus important to discern their metabolic and physiological idiosyncrasies and advance their potential applications. However, slow growth, low cell yield, and dissimilar colony morphology hinder efficient isolation of Pseudonocardia using conventional plating methods. Here, we develop the first fluorescent probe (Pse631) targeting the 16S rRNA of Pseudonocardia members. In combination with flow cytometry and cell sorting, in situ hybridization with this probe enables sensitive and specific detection of Pseudonocardia cells in mixed cultures and enriched environmental samples without significant false positives, using Escherichia coli, Bacillus subtilis, and Mycobacterium spp. as negative controls. Pseudonocardia dioxanivorans CB1190 cells labeled with Pse631 as a positive control were detected when their relative abundance in the total bacterial community was as low as 0.1%. Effective separation of Pseudonocardia cells from the mixed consortium was confirmed by quantitative PCR analysis of sorted cells. This study provides a culture-independent high-throughput molecular approach enabling effective separation of Pseudonocardia populations from complex microbial communities. This approach will not only facilitate subsequent molecular analyses including species identification and quantification, but also advance understanding of their catabolic capacities and functional molecular diversity.

Whole-Genome Sequence of the 1,4-Dioxane-Degrading Bacterium Mycobacterium dioxanotrophicus PH-06

Abstract: We report here the complete genome sequence of Mycobacterium dioxanotrophicus PH-06, which is capable of using 1,4-dioxane as a sole source of carbon and energy. The reported sequence will enable the elucidation of this novel metabolic pathway and the development of molecular biomarkers to assess bioremediation potential at contaminated sites.

Graphitic Carbon Nitride (g-C3N4)-Based Photocatalysts for Artificial Photosynthesis and Environmental Remediation: Are We a Step Closer To Achieving Sustainability?

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...

Advanced Oxidation Processes for Organic Contaminant Destruction Based on the Fenton Reaction and Related Chemistry

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.