Dyes decolorization using silver nanoparticles supported on nanometric diamond as highly efficient photocatalyst under natural Sunlight irradiation

[EN] Herein we report that silver nanoparticles supported on commercial diamond nanoparticles functionalized with hydroxyl groups (D3) is a cost-effective heterogeneous catalyst for the decolorization of different synthetic dyes (Methylene Blue, Orange II, Acid Red 1 or Rhodamine B) using H2O2 as oxidant under natural Sunlight irradiation. Importantly, the photocatalytic activity of Ag/D3 is higher than that of analogous catalysts based on Ag NPs supported on graphite or activated carbon and similar to that of costly Au/D3 catalyst or the benchmark Ag/TiO2 material. Ag/D3 stability was established by performing consecutive reuses, without observing either decrease of the catalytic activity or metal leaching, while particle size increase occurs in a low extent. Productivity tests allow determining a minimum TON for dyes and H2O2 of about 500 and 6000, respectively. © 2016 Elsevier B.V. All rights reserved. All rights reserved.Financial support by the Spanish Ministry of Economy and Competitiveness (Severo Ochoa, CTQ2012-32315 and CTQ2014-53292-R) is gratefully acknowledged. Generalidad Valenciana is also thanked for funding (Prometeo 2012/013). European Commission has been gratefully acknowledged for granting Erasmus Mundus Action-2 (SVAAGATA) fellowship to the first author for carrying out this work in Department of Chemistry, Universitat Politecnica de Valencia, Valencia, Spain.Manickam-Periyaraman, P.; Espinosa, SM.; Espinosa-López, JC.; Navalón Oltra, S.; Subramanian, S.; Alvaro Rodríguez, MM.; García Gómez, H. (2016). Dyes decolorization using silver nanoparticles supported on nanometric diamond as highly efficient photocatalyst under natural Sunlight irradiation. Journal of Environmental Chemical Engineering. 4(4):4485-4493. https://doi.org/10.1016/j.jece.2016.10.011S448544934

Solar photo-Fenton at mild conditions to treat a mixture of six emerging pollutants

The applicability of photo-Fenton to degrade a mixture of emerging pollutants (EPs) namely amoxycillin, acetaminophen, acetemiprid, caffeine, clofibric acid and carbamazepine has been studied at different scenarios. At high concentrations, acidic photo-Fenton was able to achieve a fast removal of the EPs. Although, complete mineralization was not reached, the toxicity of the solution was decreased according to the respiration of activated sludge and luminescence of Vibrio fischeri assays, although according to this last assay a transitory enhancement of the toxicity was found, attributable to the formation of toxic byproducts such as phenols, chlorophenols and chlorinated pyrydines. Experiments carried out with 5 mg/l of each EP showed that at neutral media the process was two orders of magnitude less efficient than at acidic pH, although it was still able to remove the EPs. The aqueous matrix has a remarkable effect on the process as the presence of humic acids increased the reaction rate and inorganic salts played an inhibitory role. Finally, experiments performed with 10 lg/l of each EP showed that under those experimental conditions nearly complete removal of the EPs was reached with neutral photo-Fenton after 120 min of irradiation; in this case, humic substances played a disfavorable role.We want to thank the financial support of Spanish Ministerio de Ciencia e Innovacion (CTQ 2009-13459-0O5-03) and (CTQ 2009-3459-C05-01).Bernabeu García, A.; Palacios Guillem, S.; Vicente Candela, R.; Vercher Pérez, RF.; Malato Rodríguez, S.; Arques Sanz, A.; Amat Payá, AM. (2012). Solar photo-Fenton at mild conditions to treat a mixture of six emerging pollutants. Chemical Engineering Journal. 198:65-72. https://doi.org/10.1016/j.cej.2012.05.056S657219

Molecular dynamics simulation of humic substances

© 2014, Orsi. Humic substances (HS) are complex mixtures of natural organic material which are found almost everywhere in the environment, and particularly in soils, sediments, and natural water. HS play key roles in many processes of paramount importance, such as plant growth, carbon storage, and the fate of contaminants in the environment. While most of the research on HS has been traditionally carried out by conventional experimental approaches, over the past 20 years complementary investigations have emerged from the application of computer modeling and simulation techniques. This paper reviews the literature regarding computational studies of HS, with a specific focus on molecular dynamics simulations. Significant achievements, outstanding issues, and future prospects are summarized and discussed

Cloning retinoid and peroxisome proliferator-activated nuclear receptors of the Pacific oyster and in silico binding to environmental chemicals

This is the final version of the article. Available from Public Library of Science via the DOI in this record.Disruption of nuclear receptors, a transcription factor superfamily regulating gene expression in animals, is one proposed mechanism through which pollution causes effects in aquatic invertebrates. Environmental pollutants have the ability to interfere with the receptor's functions through direct binding and inducing incorrect signals. Limited knowledge of invertebrate endocrinology and molecular regulatory mechanisms, however, impede the understanding of endocrine disruptive effects in many aquatic invertebrate species. Here, we isolated three nuclear receptors of the Pacific oyster, Crassostrea gigas: two isoforms of the retinoid X receptor, CgRXR-1 and CgRXR-2, a retinoic acid receptor ortholog CgRAR, and a peroxisome proliferator-activated receptor ortholog CgPPAR. Computer modelling of the receptors based on 3D crystal structures of human proteins was used to predict each receptor's ability to bind to different ligands in silico. CgRXR showed high potential to bind and be activated by 9-cis retinoic acid and the organotin tributyltin (TBT). Computer modelling of CgRAR revealed six residues in the ligand binding domain, which prevent the successful interaction with natural and synthetic retinoid ligands. This supports an existing theory of loss of retinoid binding in molluscan RARs. Modelling of CgPPAR was less reliable due to high discrepancies in sequence to its human ortholog. Yet, there are suggestions of binding to TBT, but not to rosiglitazone. The effect of potential receptor ligands on early oyster development was assessed after 24h of chemical exposure. TBT oxide (0.2μg/l), all-trans retinoic acid (ATRA) (0.06 mg/L) and perfluorooctanoic acid (20 mg/L) showed high effects on development (>74% abnormal developed D-shelled larvae), while rosiglitazone (40 mg/L) showed no effect. The results are discussed in relation to a putative direct (TBT) disruption effect on nuclear receptors. The inability of direct binding of ATRA to CgRAR suggests either a disruptive effect through a pathway excluding nuclear receptors or an indirect interaction. Our findings provide valuable information on potential mechanisms of molluscan nuclear receptors and the effects of environmental pollution on aquatic invertebrates.The study was funded by the Centre for Environment, Fisheries and Aquaculture Science (Cefas; https://www.cefas.co.uk) and by the University of Exeter (http://www.exeter.ac.uk)