Simón Navarro

University of Murcia, Murcia, Murcia, Spain

Are you Simón Navarro?

Claim your profile

Publications (78)192.38 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: Triazole fungicides (TZFs) are sterol biosynthesis inhibitors (SBIs). The mechanism of action of the azole (triazole and imidazole) fungicides lies in their ability to interfere with the biosynthesis of fungal biosteroids and inhibit ergosterol biosynthesis. They are classified as demethylation inhibitors (DMIs), the most important SBIs. Based on the current information, an overview on the behavior and fate of TZF residues during malting and brewing stages (mashing, boiling, and fermentation) is reviewed. In the first phase, TZF residues may remain into the malt. Later, TZF residues can be transferred from the malt to sweet wort and beer inducing in some cases of stuck/sluggish fermentation for both lager and ale beer. As a consequence, some organoleptic properties of the beer may be altered. Therefore, studies to examine the behavior of TZFs during beer brewing are necessary to assess the beer quality and perform a dietary risk assessment.
    No preview · Chapter · Dec 2015
  • [Show abstract] [Hide abstract]
    ABSTRACT: Leaching, the movement of water and chemicals into deeper soil layers and groundwater is a subject of worldwide interest because a high percentage of drinking water is extracted from groundwater. The objective of this study was to evaluate the potential leaching and persistence of sixteen pesticides (one fungicide, three nematicides/insecticides, and twelve herbicides) for three Mediterranean agricultural soils with similar texture (clay loam) but different organic matter content (1.2-3.1%). Adsorption was studied in batch experiments and leaching was tested using disturbed soil columns (40 cm length × 4 cm i.d.). Degradation studies were carried out during 120 days under laboratory conditions. Mobility experiments showed that pesticides can be grouped according to their potential leaching. Thus, pesticides showing medium leachability were included in group 1 (referred as G1) while those with high leachability were termed as G2. The differences observed in the leachability can be attributed to the different organic carbon (OC) content in the soils (0.7-1.8%). Values of log KOC were higher in the order: soil C > soil B > soil A, which agrees with the OC content in each soil. The calculated half-lives ranged from 4.2 days for carbofuran in soil A to 330 days for prometon in soil C. As a general rule, when higher OC content in the soil the greater persistence of the pesticide was observed as a consequence of the increased adsorption. The first order kinetics model satisfactorily explains the disappearance of the studied pesticides in the soil.
    No preview · Article · Dec 2015 · SPANISH JOURNAL OF AGRICULTURAL RESEARCH
  • N. Vela · J. Fenoll · I. Garrido · G. Navarro · M. Gambín · S. Navarro
    [Show abstract] [Hide abstract]
    ABSTRACT: Heterogeneous photocatalysis offers an alternative for the treatment of wastewater containing refractory pollutants. The photocatalytic degradation of metamitron and metribuzin, asymmetrical triazine compounds used worldwide as herbicides, was investigated in aqueous suspension of different commercial TiO2 nanopowders with different composition of anatase/rutile phases, using artificial UV-A light. In addition, we have studied the role of the most important operating parameters (catalyst loading, effect of electron acceptor, pH, light intensity, initial concentration of pollutants, and interfering substances) on the photooxidation of both herbicides. TiO2 P25 (70% anatase/30% rutile) was found to be highly active for herbicide decomposition. The progress of photocatalytic degradation of both herbicides has been observed by monitoring the change in substrate concentration using HPLC/MS2. Results showed that the addition of TiO2 in tandem with an electron acceptor like Na2S2O8 strongly enhances the degradation rate of metamitron and metribuzin in comparison with photolytic test. The degradation of these herbicides followed a pseudo-first order kinetics. The time required for 50% degradation was lower than 8 min for both. Thus, complete disappearance was achieved after 30 min of illumination in the TiO2/Na2S2O8 system. Both herbicides were rapidly deaminated.
    No preview · Article · Sep 2015 · Catalysis Today
  • [Show abstract] [Hide abstract]
    ABSTRACT: The photodegradation of flubendiamide (benzenedicarboxamide insecticide), a relatively new insecticide was investigated in aqueous suspensions of binary (ZnO and TiO2 ) and ternary (Zn2 TiO4 and ZnTiO3 ) oxides under artificial light (300-460 nm) irradiation. Photocatalytic experiments showed that the addition of semiconductors, especially ZnO and TiO2 , in tandem with an electron acceptor (Na2 S2 O8 ) enhances the degradation rate of this compound in comparison with those carried out with catalyst alone and photolytic tests. The photocatalytical degradation of flubendiamide using ZnO/Na2 S2 O8 and TiO2 /Na2 S2 O8 followed first-order kinetics. In addition, desiodo-flubendiamide was identified during the degradation of flubendiamide. Finally, application of these reaction systems in different waters (tap, leaching and watercourse) showed the validity of the treatments, which allowed the removal of flubendiamide residues in these drinking and environmental water samples. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.
    No preview · Article · Jun 2015 · Photochemistry and Photobiology
  • [Show abstract] [Hide abstract]
    ABSTRACT: The photocatalytic degradation of three neonicotinoid insecticides (NIs), thiamethoxam (TH), imidacloprid (IM) and acetamiprid (AC), in pure water has been studied using zinc oxide (ZnO) and titanium dioxide (TiO2) as photocatalysts under natural sunlight and artificial light irradiation. Photocatalytic experiments showed that the addition of these chalcogenide oxides in tandem with the electron acceptor (Na2S2O8) strongly enhances the degradation rate of these compounds in comparison with those carried out with ZnO and TiO2 alone and photolytic tests. Comparison of catalysts showed that ZnO is the most efficient for the removal of such insecticides in optimal conditions and at constant volumetric rate of photon absorption. Thus, the complete disappearance of all the studied compounds was achieved after 10 and 30 min of artificial light irradiation, in the ZnO/Na2S2O8 and TiO2/Na2S2O8 systems, respectively. The highest degradation rate was noticed for IM, while the lowest rate constant was obtained for AC under artificial light irradiation. In addition, solar irradiation was more efficient compared to artificial light for the removal of these insecticides from water. The main photocatalytic intermediates detected during the degradation of NIs were identified.
    No preview · Article · May 2015 · Environmental Science and Pollution Research
  • [Show abstract] [Hide abstract]
    ABSTRACT: The photocatalytic degradation of a new insecticide, chlorantraniliprole (CL) was studied in aqueous suspensions of binary (ZnO and TiO2) and ternary (Zn2TiO4) oxides of Zn and Ti under artificial light irradiation (300-460 nm). Photocatalytic experiments showed that the addition of semiconductors, paired with Na2S2O8 as electron acceptor, greatly improved the elimination of CL in aqueous slurries compared with ZnO and TiO2 alone, and photolytic tests. The reaction rates significantly increased, especially for ZnO/Na2S2O8 and TiO2/Na2S2O8 systems with half-lives of 53 and 71 min, respectively. Zn2TiO4/Na2S2O8 appears to be less effective than ZnO/Na2S2O8 and TiO2/Na2S2O8, although it can be used as photocatalyst for CL oxidation (t1/2 = 462 min). Seven phototransformation products were identified by liquid chromatography tandem mass spectrometry (LC-MS2) and liquid chromatography time of flight mass spectrometry (LC-TOF/MS) techniques while its mineralization was followed using dissolved organic carbon (DOC) analysis. The probable photooxidation pathways are proposed and discussed, being hydroxylation and N-demethylation the major routes of phototransformation observed.
    No preview · Article · Mar 2015 · The Chemical Engineering Journal
  • [Show abstract] [Hide abstract]
    ABSTRACT: The photocatalytic degradation of pirimicarb in pure water has been studied using zinc oxide (ZnO), titanium dioxide (TiO2) and zinc titanates (Zn2TiO4 and ZnTiO3) under artificial light (300-460 nm) irradiation. Comparison of catalysts showed that TiO2 is the most efficient for the removal of pirimicarb and their transformation products. To obtain a better understanding of the mechanistic details of these ZnO-TiO2-assisted photodegradation of pirimicarb, the transformation products of the processes were identified by liquid chromatography tandem mass spectrometry (LC-MS2) and liquid chromatography time of flight mass spectrometry (LC-TOF/MS) techniques. The probable photodegradation pathways are proposed and discussed. The main steps involved: N-dealkylation of the 2-dimethylamino group to form the carbamate and decarbamoylation of the carbamate moiety with further N-dealkylation of the 2-dimethylamino group to have the hydroxypyrimidines.
    No preview · Article · Feb 2015 · Journal of Photochemistry and Photobiology A Chemistry
  • [Show abstract] [Hide abstract]
    ABSTRACT: In this study, the leaching of 14 substituted phenylurea herbicides (PUHs) through disturbed soil columns packed with three different soils was investigated in order to determine their potential for groundwater pollution. Simultaneously, a series of experiments were conducted to demonstrate the effect of four different organic wastes (composted sheep manure (CSM), composted pine bark (CPB), spent coffee grounds (SCG) and coir (CR)) on their mobility. All herbicides, except difenoxuron, showed medium/high leachability through the unamended soils. In general, addition of agro-industrial and composted organic wastes at a rate of 10 % (w/w) increased the adsorption of PUHs and decreased their mobility in the soil, reducing their leaching. In all cases, the groundwater ubiquity score (GUS) index was calculated for each herbicide on the basis of its persistence (as t ½) and mobility (as K OC). The results obtained point to the interest in the use of agro-industrial and composted organic wastes in reducing the risk of groundwater pollution by pesticide drainage.
    No preview · Article · Oct 2014 · Environmental Science and Pollution Research
  • [Show abstract] [Hide abstract]
    ABSTRACT: In this study, we examined the effect of four different organic wastes (OW)-composted sheep manure (CSM), spent coffee grounds (SCG), composted pine bark (CPB) and coir (CR)-on the potential groundwater pollution of propanil and isoxaben (herbicides), cadusafos (insecticide) and pencycuron (fungicide) under laboratory conditions. For this purpose, leaching studies were conducted using disturbed soil columns filled with a clay loam soil (Hipercalcic calcisol). The addition of organic matter (OM) drastically reduced the movement of the studied pesticides. The results obtained point to the interest in the use of agro-industrial and composted OW in reducing the groundwater pollution by pesticide drainage.
    No preview · Article · Aug 2014 · Journal of Environmental Science and Health Part B Pesticides Food Contaminants and Agricultural Wastes
  • [Show abstract] [Hide abstract]
    ABSTRACT: In this study, we examined the effect of four different organic wastes - composted sheep manure (CSM), spent coffee grounds (SCG), composted pine bark (CPB) and coir (CR) - on the sorption, persistence and mobility of eight symmetrical and two asymmetrical-triazine herbicides: atrazine, propazine, simazine, terbuthylazine (chlorotriazines), prometon (methoxytriazine), prometryn, simetryn, terbutryn (methylthiotriazines), metamitron and metribuzin (triazinones). The downward movement of herbicides was monitored using disturbed soil columns packed with a clay loam soil (Hipercalcic calcisol) under laboratory conditions. For unamended and amended soils, the groundwater ubiquity score (GUS) was calculated for each herbicide on the basis of its persistence (as t½) and mobility (as KOC). All herbicides showed medium/high leachability through the unamended soils. The addition of agro-industrial and composted organic wastes at a rate of 10% (w:w) strongly decreased the mobility of herbicides. Sorption coefficients normalized to the total soil organic carbon (KOC) increased in the amended soils. These results suggest that used organic wastes could be used to enhance the retention and reduce the mobility of the studied herbicides in soil.
    No preview · Article · Jun 2014 · Science of The Total Environment
  • [Show abstract] [Hide abstract]
    ABSTRACT: Strategies for remediation of polluted soils are needed to accelerate the degradation and natural attenuation of pesticides. This study was conducted to assess the effect of solarization (S) and biosolarization (BS) during the summer season using organic wastes (composted sheep manure and sugar beet vinasse) for the bioremediation of soil containing residues of terbuthylazine and linuron. The results showed that both S and BS enhanced herbicide dissipation rates compared with the non-disinfected control, an effect which was attributed to the increased soil temperature and organic matter. Linuron showed similar behavior under S and BS conditions. However, terbuthylazine was degraded to a greater extent in the biosolarization experiment using sugar beet vinasse than in the both the solarization and biosolarization experiments using composted sheep manure treatments. The main organic intermediates detected during the degradation of terbuthylazine and linuron were identified, enabling the main steps of degradation to be proposed. The results confirm that both S and BS techniques can be considered as a remediation tools for polluted soils containing these herbicides.
    No preview · Article · Jun 2014 · Journal of Environmental Management
  • J Fenoll · N Vela · I Garrido · G Pérez-Lucas · S Navarro
    [Show abstract] [Hide abstract]
    ABSTRACT: The photodegradation of indoxacarb, a broad spectrum foliar insecticide and spinosad, a natural insecticide containing two active ingredients, spinosyn A (major component) and spinosyn D (minor component), was studied in aqueous suspensions of binary (ZnO and TiO2) and ternary (Zn2TiO4 and ZnTiO3) oxides under artificial light (300-460 nm) irradiation. As expected, the influence of the semiconductor materials on the degradation of both was very significant in all cases. Photocatalytic experiments showed that the addition of semiconductors in tandem with Na2S2O8 as electron acceptor strongly improved the removal of indoxacarb and spinosad in water compared with the photolytic tests. The reaction rates significantly increased, especially for the ZnO/Na2S2O8 and TiO2/Na2S2O8 systems. The first-order equation (monophasic model) satisfactorily explained the disappearance process, although it offered no explanation for the small concentrations remaining in the process.
    No preview · Article · May 2014 · Environmental Science and Pollution Research
  • [Show abstract] [Hide abstract]
    ABSTRACT: The photocatalytic degradation of fipronil in drinking water was studied using zinc oxide (ZnO) and titanium dioxide (TiO2) as photocatalyst under irradiation by solar and artificial light. Photocatalytic experiments showed that the addition of semiconductors in tandem with the oxidant (Na2S2O8) strongly enhances the degradation rate of fipronil in comparisons carried out with photolytic experiments under artificial light. However, under solar irradiation, the photocatalytic decomposition of fipronil occurs very slowly. The residual levels of fipronil for ZnO/Na2S2O8 and TiO2/Na2S2O8 after 60 min of illumination at a constant volumetric rate of photon absorption in the photoreactor were 0.8 and 1.5 μg/L, respectively. The main intermediates (fipronil-sulfone, fipronil-sulfide, fipronil-desulfinyl and fipronil-carboxamide) detected during the degradation of fipronil in water were identified.
    No preview · Article · May 2014 · Journal of the Taiwan Institute of Chemical Engineers
  • [Show abstract] [Hide abstract]
    ABSTRACT: In the present work, potential groundwater pollution by methabenzthiazuron (MTBU) and the effect of three different amendments (composted sheep manure, composted pine bark and spent coffee grounds) on its mobility were investigated under laboratory conditions. The efficiency of ZnO and TiO2 suspensions in the photocatalytic degradation of MTBU in leaching water was also investigated. The relative and cumulative breakthrough curves were obtained from disturbed soil columns. The presence and/or addition of organic matter drastically reduced the movement of the herbicide. On other hand, photocatalytic experiments showed that the addition of ZnO and TiO2 strongly enhances the degradation rate of this herbicide compared with the results of photolytic experiments under artificial light. ZnO appeared to be more effective in MTBU oxidation than TiO2. The results obtained point to the interest of using organic wastes and heterogeneous photocatalysis for reducing the pollution of groundwater by pesticide drainage.
    No preview · Article · Apr 2014 · Journal of Environmental Sciences
  • Source

    Full-text · Article · Jan 2014
  • [Show abstract] [Hide abstract]
    ABSTRACT: Sulfonylurea herbicides (SUHs) are a family of environmentally compatible herbicides but their high water solubility, moderate to high mobility through the soil profile, and slow degradation rate make them potential contaminants of groundwater as demonstrated in this paper. The photodegradation of a mixture of 30 SUHs in aqueous suspensions of semiconductor materials (ZnO and TiO2 in tandem with Na2S2O8 as electron acceptor) under artificial light (300-460 nm) irradiation was investigated. As expected, the influence of both semiconductors on the degradation of SUHs was very significant in all cases. Photocatalytic experiments show that the addition of photocatalyst, especially for the ZnO/Na2S2O8 system, greatly improves the removal of SUHs compared with photolytic tests, significantly increasing the reaction rates. The first-order equation (monophasic model) satisfactorily explained the disappearance process although it overlooked small residues remaining late in the process. These residues are important from an environmental point of view and the Hoerl function (biphasic model), was a better predicter of the results obtained. In our conditions, the average time required for 90% degradation was about 3 and 30 min for ZnO/Na2S2O8 and TiO2/Na2S2O8 systems, respectively.
    No preview · Article · Oct 2013 · Journal of Environmental Management
  • [Show abstract] [Hide abstract]
    ABSTRACT: The photocatalyzed degradation of the biocides chlorotoluron, diuron, fluometuron, isoproturon and linuron (substituted phenylurea herbicides) was investigated in aqueous suspensions of ZnO, TiO(2), WO(3), SnO(2) and ZnS at pilot plant scale under natural sunlight. Comparison of the five catalysts showed that ZnO is the most effective for catalyzing the removal of all the compounds studied. The primary degradation of the herbicides followed a pseudo-first order kinetics. In our conditions, the time required for 90% degradation ranged from 23 to 47min for isoproturon and linuron, respectively, when using the tandem ZnO/Na(2)S(2)O(8). Eight transformation products were identified by HPLC-MS(2) during the experiments, although at the end of the photoperiod (240min), their concentrations were below detection limits. Based on derivative identification, the proposed metabolic pathways would involve N-demethylation and N-demethoxylation of the N-methoxy-N-methyl substituted ureas and N-demethylation of the N,N-dimethylurea-substituted compounds.
    No preview · Article · Jan 2013 · Chemosphere
  • [Show abstract] [Hide abstract]
    ABSTRACT: In this work the solar-photocatalytical degradation of carbofuran in leaching water has been studied using zinc oxide (ZnO) and different mixed-phase (rutile/anatase) titanium dioxide (TiO2) at pilot plant scale. Comparison of catalysts showed that ZnO is the most efficient for catalyzing the removal of carbofuran and their main organic intermediates. The residual levels of carbofuran at the end of the experiment (240 min) were 0.1, 22.4, 62.8, 68.4 μg L−1 for ZnO, TiO2 P25 Degussa (70A/30R), TiO2 rutile (25A/75R) and TiO2 anatase (90A/10R), respectively. The primary degradation of carbofuran followed pseudo-first order kinetics. The analysis and evolution of the intermediates suggest that oxidation of the CO bond on the carbamate group and 3C position of the furan ring as the main metabolic pathway.
    No preview · Article · Jan 2013 · Journal of Photochemistry and Photobiology A Chemistry
  • [Show abstract] [Hide abstract]
    ABSTRACT: The photocatalytic degradation of sixteen substituted phenylurea herbicides (PUHs) in pure water has been studied using zinc oxide (ZnO) and titanium dioxide (TiO(2)) as photocatalyst under artificial light irradiation. Photocatalytic experiments showed that the addition of these chalcogenide oxides in tandem with the oxidant (Na(2)S(2)O(8)) strongly enhances the degradation rate of these compounds in comparison with those carried out with ZnO and TiO(2) alone and photolytic tests. Comparison of catalysts showed that ZnO is the most efficient for the removal of such herbicides in optimal conditions and at constant volumetric rate of photon absorption in the photoreactor. Thus, the complete disappearance of all the studied compounds was achieved after 20min of illumination in the ZnO/Na(2)S(2)O(8) system. The main photocatalytic intermediates detected during the degradation of PUHs were identified. The probable photodegradation pathways were proposed and discussed. The main steps involved: N-demethylation of the N,N-dimethylurea-substituted compounds followed of N-demethylation and N-demethoxylation of the N-methoxy-N-methyl-substituted ureas and hydroxylation of aromatic rings and their aliphatic side-chains of both, parent compounds and intermediates.
    No preview · Article · Dec 2012 · Journal of hazardous materials
  • [Show abstract] [Hide abstract]
    ABSTRACT: The shortage of water in Mediterranean hydrographic basins of the Iberian Peninsula has led to the development of desalination plants which use reverse osmosis to supply drinking water. This has caused a variation of the organoleptic characteristics in the water supply which have led to the appearance of medicinal taste and, to a lesser extent, odour. The aim of this study was to determine the substances that have led to this state of affairs. After analytical determinations by SPME-GC/MS, it was found that bromophenols (2-bromophenol, 2,4-and 2,6-dibromophenol) are responsible and their sensory threshold being in some cases lower than 10 ng L− 1. The chlorination (5 mg Cl L− 1) of the desalinated water with bromide levels (0.3 to 0.8 mg L− 1) leads to the development of bromophenols that even after one month have maintained high levels of concentration. This fact does not occur in the case of continental waters with low bromide content (0.1 mg L− 1) when they are treated in the same way.
    No preview · Article · Dec 2012 · Desalination