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.

Climate change would increase the water intensity of irrigated corn ethanol.

Abstract: Changes in atmospheric CO2 concentrations, temperature, and precipitation affect plant growth and evapotranspiration. However, the interactive effects of these factors are relatively unexplored, and it is important to consider their combined effects at geographic and temporal scales that are relevant to policymaking. Accordingly, we estimate how climate change would affect water requirements for irrigated corn ethanol production in key regions of the U.S. over a 40 year horizon. We used the geographic-information-system-based environmental policy integrated climate (GEPIC) model, coupled with temperature and precipitation predictions from five different general circulation models and atmospheric CO2 concentrations from the Special Report on Emissions Scenarios A2 emission scenario of the Intergovernmental Panel on Climate Change, to estimate changes in water requirements and yields for corn ethanol. Simulations infer that climate change would increase the evaporative water consumption of the 15 billion ga...

Pcb biodegradation in aged contaminated soil: interactions between exogenous phanerochaete chrysosporium and indigenous microorganisms

Abstract: This work investigated whether the interaction between the white-rot fungus Phanerochaete chrysosporium and indigenous microorganisms could enhance polychlorinated biphenyl (PCB) removal from historically contaminated soil in aerobic microcosms. The PCB mixture was composed mainly of 14% tri-, 20% tetra-, 9% penta-, 17% hexa-, 26% hepta-, 11% octa-, and 3% nona-chlorobiphenyl (CB) congeners, determined by GC/MS. The fungus, which was grown on sugarcane bagasse and added via this solid substrate, successfully colonized the contaminated soil. The added fungi and the indigenous soil community biodegraded most PCB congeners, with removing efficiencies ranging from 13% to 100% for the 45-day incubation period. The interaction between the fungus and the microorganisms present in the added bagasse inhibited both heterotrophic activity (measured by CO2 evolution) and PCB degradation, suggesting a possible antagonism. In contrast, analysis of variance (ANOVA) inferred a synergistic effect between fungus and soil m...

Exploring the Correlation between Halorespirer Biomarker Concentrations and TCE Dechlorination Rates

Abstract: Whether the concentration of selected genetic biomarkers could be correlated to the rate of trichloroethylene (TCE) reductive dechlorination was investigated. Samples from a pilot-scale aquifer that had been bioaugmented with a halorespiring mixed culture to promote bioremediation of a chlorinated solvent source zone were used for this purpose. Dechlorination rates were determined in batch microcosms, and real-time quantitative polymerase chain reaction (qPCR) analyses were used to estimate the concentration of phylogenetic 16S rRNA for total Bacteria and for Dehalococcoides spp., and the catabolic gene tceA and its expressed mRNA. The first-order dechlorination rate coefficient ( k′ ) obtained from the mixed culture used to bioaugment the pilot scale aquifer ranged from 0.033 to 0.662 h−1 . Samples collected from the source zone showed the highest k′ value ( 0.03 h−1 ±0.011 ; n=6 ) as well as the highest concentration of the biomarkers tested: 2.2±0.5× 107 genes∕μL for total Bacteria, 1.97±0.1× 107 genes...

7-ketocholesterol catabolism by Rhodococcus jostii RHA1.

Abstract: Oxysterols from steroid autooxidation have numerous harmful effects, but their biodegradation is poorly understood. Microarrays were used to study mineralization of the most common oxysterol, 7-ketocholesterol (7KC), by Rhodococcus jostii RHA1. Growth on 7KC versus growth on cholesterol resulted in 363 differentially expressed genes, including upregulation of two large gene clusters putatively encoding steroid catabolism. Despite this difference, 7KC degradation required key genes involved in cholesterol degradation, indicating a common catabolic route.

Synthesis and characterization of green agents coated Pd/Fe bimetallic nanoparticles

Abstract: The low stability and mobility of nanoparticles in liquid phase is one of the biggest challenges for the application of zero-valent iron (ZVI) technology. In this research, three green agents, polyethylene glycol (PEG), starch, and guar gum were coated on Pd/Fe bimetallic nanoparticles (NPs) to enhance the stability and reactivity of Pd/Fe NPs. The modified NPs (PEG-Pd/Fe, Starch-Pd/Fe, and Guar gum-Pd/Fe NPs) were characterized in terms of specific surface area, particle size, shape, morphology, and structural feature, etc. The results show that the diameters of modified Pd/Fe NPs are in the range of 60–100 nm. Compared with the pristine unmodified Pd/Fe NPs, the aggregations of modified Pd/Fe NPs were successfully reduced. XRD patterns indicate that modified Pd/Fe NPs remained the body centered cubic crystal structure, and the modification process contributed to improve the antioxidant ability. 2,4-Dichlorophenol (2,4-DCP) dechlorination experiments show that physico-chemical properties of the three modifiers have different effects on the reactivity of modified Pd/Fe NPs. The initial pH value of the reaction system had complex effects on the dechlorination of 2,4-DCP by using modified Pd/Fe NPs. Activation energies of pristine, PEG-Pd/Fe, Starch-Pd/Fe, and Guar gum-Pd/Fe NPs were calculated to be 39.47 kJ/mol, 38.66 kJ/mol, 36.59 kJ/mol, and 33.88 kJ/mol, respectively, implying that the modification process can enhance the dechlorination rate of Pd/Fe NPs, and that catalytic hydrodechlorination process of 2,4-DCP with modified Pd/Fe NPs is a surface-controlled chemical reaction.

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.