Simón Navarro

University of Murcia, Murcia, Murcia, Spain

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Publications (67)166.75 Total impact

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    ABSTRACT: Photocatalytic oxidation of pirimicarb in water was studied.•The study was performed using ZnO–TiO2 systems under artificial irradiation.•ZnO and TiO2 enhanced photodegradation in comparison with Zn2TiO4 and ZnTiO3.•Pirimicarb was totally degraded using ZnO and TiO2.•5 intermediates were identified and a mechanism of degradation has been proposed.
    Journal of Photochemistry and Photobiology A Chemistry 02/2015; 298. · 2.29 Impact Factor
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    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.
    Environmental Science and Pollution Research 10/2014; · 2.76 Impact Factor
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    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.
    Journal of Environmental Science and Health Part B Pesticides Food Contaminants and Agricultural Wastes 08/2014; 49(8):601-608. · 1.10 Impact Factor
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    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.
    Science of The Total Environment 06/2014; 493C:124-132. · 3.16 Impact Factor
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    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.
    Journal of Environmental Management 06/2014; 143C:106-112. · 3.19 Impact Factor
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    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.
    Environmental Science and Pollution Research 05/2014; · 2.76 Impact Factor
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    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.
    Journal of the Taiwan Institute of Chemical Engineers 05/2014; 45(3):981–988. · 2.64 Impact Factor
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    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.
    Journal of Environmental Sciences 04/2014; 26(4):757-764. · 1.92 Impact Factor
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    Journal of Environmental Management. 01/2014; 143:106–112.
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    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.
    Journal of Environmental Management 10/2013; 130C:361-368. · 3.06 Impact Factor
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    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.
    Chemosphere 01/2013; · 3.14 Impact Factor
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    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.
    Journal of hazardous materials 12/2012; 244-245C:370-379. · 4.33 Impact Factor
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    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.
    Desalination 12/2012; 307:1–8. · 3.96 Impact Factor
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    ABSTRACT: A sensitive method for the simultaneous determination of 30 sulfonylurea herbicides in tap and leaching waters has been developed. Liquid chromatography tandem-mass spectrometry (LC-MS(2)) in electrospray ionization positive mode was used for the separation, identification and quantification of these compounds. The procedure involves a preconcentration step based on solid-phase extraction with a silica-based bonded C(18) cartridge (Sep-Pak Plus) and a N-vinyl-pyrrolidone polymer cartridge (Oasis HLB). The best results were obtained with Oasis HLB using methanol as elution solvent. Average recoveries of 30 analytes from water samples were in the range of 79-115% with a relative standard deviation of <6.1%. The limits of quantification (LOQs) obtained in tap and leaching water samples were in the range of 0.1-5.9 and 0.4-5.8ngL(-1), respectively. The proposed method was used to determine sulfonylurea herbicide levels in leaching water samples taken from three lysimeters located in an experimental greenhouse.
    Talanta 11/2012; 101:273-82. · 3.50 Impact Factor
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    ABSTRACT: Heterogeneous photocatalysis with different semiconductor materials such as zinc oxide (ZnO), titanium dioxide (TiO2), tungsten (VI) oxide (WO3), tin (IV) oxide (SnO2) and zinc sulphide (ZnS) in aqueous suspensions has been investigated for the removal of eight miscellaneous pesticides (ethoprophos, isoxaben, metalaxyl, metribuzin, pencycuron, pendimethalin, propanil and tolclofos-methyl). The experiments were carried out at pilot plant scale using compound parabolic collectors under natural sunlight, comparison of catalysts showed that ZnO is the most efficient for catalyzing the removal of these compounds. The photocatalysis of these compounds using ZnO followed first-order kinetics. The residual levels at the end (240 min) of the ZnO experiment were lower than 0.8 μg L−1.
    Chemical Engineering Journal 09/2012; s 204–206:54–64. · 4.06 Impact Factor
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    ABSTRACT: A sensitive multiresidue method for the simultaneous determination of sixteen phenylurea herbicides and their main metabolites in amended soils has been developed. Liquid chromatography tandem-mass spectrometry (LC-MS²) in electrospray ionization positive mode was used for the separation, identification and quantification of these compounds. The procedure involves initial single phase extraction of soil sample with acetonitrile by sonication, followed by liquid-liquid partitioning formed by addition of NaCl. The average recovery by the LC-MS² method obtained for these compounds varied from 76.2 to 107.9% with a relative standard deviation ranging from 2.1 to 5.8%. The method presents good linearity (R²>0.99) over the range assayed 10-1000 μg L⁻¹ (except N-phenylurea 50-1000 μg L⁻¹). The detection limits for the compounds studied varied from 0.1 to 9.0 ng g⁻¹.
    Journal of Chromatography A 08/2012; 1257:81-8. · 4.61 Impact Factor
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    ABSTRACT: In the present study, the photocatalytic degradation of five s-triazine (simazine, prometryn, terbutryn, atrazine and terbuthylazine) and three chloroacetanilide (propachlor, s-metolachlor, alachlor) herbicides in leaching water has been investigated. Zinc oxide (ZnO) and titanium dioxide (TiO2) were used as semiconductors at pilot plant scale under natural sunlight. The addition of an oxidant (Na2S2O8) to the semiconductor suspensions led to an increase in the rate of photooxidation. Comparison of catalysts showed that ZnO was the most efficient for catalyzing the removal of the studied compounds. Thus, more than 70% of the herbicide amount initially present in the leaching water was degraded after 240 min of illumination in the ZnO/Na2S2O8 system. Finally, some hydroxy and dealkylated derivatives of s-triazine herbicides were isolated during the experiment.
    Journal of Photochemistry and Photobiology A Chemistry 06/2012; 238:81–87. · 2.29 Impact Factor
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    ABSTRACT: In this study, the potential groundwater pollution of 12 substituted phenylurea herbicides (chlorbromuron, chlorotoluron, diuron, fenuron, fluometuron, isoproturon, linuron, metobromuron, metoxuron, monolinuron, Monuron, and neburon) was investigated under laboratory conditions. For this purpose, leaching studies were conducted using disturbed soil columns filled with two different agricultural soils, one hypercalcic calcisol (HC) and the other endoleptic phaeozem (EP). In the case of the HC, all of the studied herbicides were found in leachates, while for the EP only, chlorbromuron, chlorotoluron, isoproturon, monolinuron, and, especially, fenuron were recovered. For both soils, the groundwater ubiquity score (GUS) index was calculated for each herbicide on the basis of its persistence (as t(1/2)) and mobility (as K(OC)). The half-lives obtained were markedly higher in the EP (217-518 days) than in the HC (71-178 days). As a consequence, higher values of GUS indexes were observed for EP. The ratio of the GUS between the EP and the HC was about 1.3.
    Journal of Agricultural and Food Chemistry 05/2012; 60(21):5279-86. · 3.11 Impact Factor
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    ABSTRACT: The photocatalytic degradation of fenamiphos in leaching water has been studied using zinc oxide (ZnO), different mixed-phase titanium dioxide (TiO2), tungsten(VI) oxide (WO3), and tin(IV) oxide (SnO2) at pilot plant scale under natural sunlight. Photocatalytic experiments showed that the addition of semiconductors in tandem with the oxidant (Na2S2O8) strongly enhances the degradation rate of fenamiphos in comparisons carried out with photolytic tests. The primary degradation of fenamiphos followed a pseudo-first order kinetics. The time required for 50% degradation was in the range 1–3 min for ZnO and TiO2. The main photocatalytic intermediates (fenamiphos-sulfoxide and fenamiphos sulfone) detected during the degradation of fenamiphos were identified. Comparison of catalysts showed that ZnO is the most efficient for catalyzing the removal of fenamiphos and their metabolites. Thus, complete disappearance of all the compounds studied achieved after 240 min of illumination in the ZnO/Na2S2O8 system.
    Applied Catalysis B Environmental 04/2012; s 115–116:31–37. · 6.01 Impact Factor
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    ABSTRACT: Polycyclic aromatic hydrocarbons (PAHs) are a class of persistent organic pollutants of special concern because they are carcinogenic and mutagenic compounds. In this paper, photodegradation of a mixture of six PAHs in groundwater at pilot plant scale is reported. Semiconductor materials (ZnO and TiO2) as photocatalysts in tandem with Na2S2O8 as oxidant under natural sunlight were used. The PAHs were benzo[a]pyrene, benzo[b]fluoranthene, benzo[ghi]perylene, benzo[k]fluoranthene, fluoranthene, and indene[1,2,3-cd]pyrene. As expected, the influence of both semiconductors on the degradation of PAHs was very significant in all cases. Photocatalytic experiments show that the addition of photocatalyst, especially for ZnO/Na2S2O8 system, strongly improves the elimination of PAHs in comparison with photolytic tests; significantly increasing the reaction rates. The first-order equation (monophasic model) satisfactorily explained the disappearance process although it ignores small residues remaining late in the process. These residues are important from an environmental point of view and the Hoerl function (biphasic model) better predict the results obtained. In our conditions, the time required for 90% degradation was in the range 7–15 min and 18–76 min for ZnO and TiO2 systems, respectively. Thus, the use of the tandem ZnO/Na2S2O8 makes possible the economical decontamination of groundwater containing non-biodegradable pollutants like PAHs.
    Journal of Photochemistry and Photobiology A Chemistry 03/2012; 232:32–40. · 2.29 Impact Factor

Publication Stats

548 Citations
166.75 Total Impact Points

Institutions

  • 1980–2014
    • University of Murcia
      • • Department of Agricultural Chemistry, Geology and Pedology
      • • Facultad de Química
      Murcia, Murcia, Spain
  • 2011–2013
    • Instituto Murciano de Investigación y Desarrollo Agrario y Alimentario
      Murcia, Murcia, Spain