Jesús J. López-Peñalver

University of Granada, Granata, Andalusia, Spain

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Publications (21)78.72 Total impact

  • M. Sánchez-Polo, I. Velo-Gala, Jesús J. López-Peñalver, J. Rivera-Utrilla
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    ABSTRACT: The objective of this study was to synthesize a molecularly imprinted polymer (MIP) for tetracycline (TC), prepared in the form of well-defined polymer microspheres, and its corresponding non-imprinted polymer (NIP). TC adsorption on these polymers was investigated, determining: (i) the interactions responsible for the adsorption, (ii) the chemical and textural characteristics of the polymers, and (iii) the role of the solvent in the process. The two polymers were characterized texturally by different techniques: (i) the surface area was larger for the MIP than for the NIP, whereas the micropore volume was considerably lower for the MIP; (ii) XPS analysis showed very high and similar surface oxygen percentages in both materials. The adsorbent properties of the materials were assessed by determining the TC adsorption isotherms: the Freundlich model indicates the high homogeneity of the MIP and Shimizu model shows the total number of binding sites was 8.7 mu mol g(-1) for the MIP vs. 0.17 mu mol g(-1) for the NIP. Analysis of the influence of pH and ionic strength revealed that adsorbent-adsorbate electrostatic interactions play a key role in TC adsorption on the MIP. The adsorption capacity of the MIP was also found to decrease with temperature, showing it to be an exothermic process.
    Microporous and Mesoporous Materials 02/2015; 203. DOI:10.1016/j.micromeso.2014.10.022 · 3.21 Impact Factor
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    ABSTRACT: This study centers on Advanced Oxidation Processes (AOPs) based on the use of iron salts and ultraviolet (UV) radiation for the removal of diatrizoate (DTZ) contrast medium, selected as a model compound resistant to all conventional natural and waste water treatment methods. We studied the effectiveness of Fenton's reagent, Iron (III) and Iron (VI) salts, and oxidation processes based on the use of UV radiation, UV/H2O2 and UV/K2S2O8, for the degradation of DTZ in aqueous medium. With Fenton's reagent, the percentage DTZ removal was independent of the initial Fe2+ concentration and was most influenced by the initial hydrogen peroxide concentration. In contrast, the Fenton-like system was affected by both initial Fe3+ and H2O2 concentration. The effects of ferrate salt-bases methods were highly dependent on the solution pH, and a higher rate constant (1.74 x 10(2) M-1 s(-1)) was obtained when dihydrogen ferrate species predominated in the medium. The UV/H2O2 system was strongly dependent on the pH and initial H2O2 concentration, showing a favorable synergic effect at H2O2 concentrations <10.0 mM. The UV/K2S2O8 system proved to be more effective than the UV/H2O2 system, with higher rate constants, which were 24.0% higher for pH = 6.5 and [DTZ](0) = 25 mg L-1. Study of the influence of the matrix on these AOPs revealed a markedly higher percentage DTZ removal and reaction rate in surface water with the UV radiation-based systems than with the iron salt-based systems. According to the total organic carbon values obtained, a high degree of mineralization was only attained with the UV/K2S2O8 system.
    Chemical Engineering Journal 04/2014; 241:504-512. DOI:10.1016/j.cej.2013.10.036 · 4.32 Impact Factor
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    ABSTRACT: Tumor expression of estrogen receptor (ER) is an important marker of prognosis, and is predictive of response to endocrine therapy in breast cancer. Several studies have observed that epigenetic events, such methylation of cytosines and deacetylation of histones, are involved in the complex mechanisms that regulate promoter transcription. However, the exact interplay of these factors in transcription activity is not well understood. In this study, we explored the relationship between ER expression status in tumor tissue samples and the methylation of the 5[prime]CpG promoter region of the estrogen receptor gene (ESR1) isolated from free circulating DNA (fcDNA) in plasma samples from breast cancer patients. Patients (n = 110) with non-metastatic breast cancer had analyses performed of ER expression (luminal phenotype in tumor tissue, by immunohistochemistry method), and the ESR1-DNA methylation status (fcDNA in plasma, by quantitative methylation specific PCR technique). Our results showed a significant association between presence of methylated ESR1 in patients with breast cancer and ER negative status in the tumor tissue (p = 0.0179). There was a trend towards a higher probability of ESR1-methylation in those phenotypes with poor prognosis i.e. 80% of triple negative patients, 60% of HER2 patients, compared to 28% and 5.9% of patients with better prognosis such as luminal A and luminal B, respectively. Silencing, by methylation, of the promoter region of the ESR1 affects the expression of the estrogen receptor protein in tumors of breast cancer patients; high methylation of ESR1-DNA is associated with estrogen receptor negative status which, in turn, may be implicated in the patient's resistance to hormonal treatment in breast cancer. As such, epigenetic markers in plasma may be of interest as new targets for anticancer therapy, especially with respect to endocrine treatment.
    BMC Cancer 02/2014; 14(1):59. DOI:10.1186/1471-2407-14-59 · 3.32 Impact Factor
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    ABSTRACT: Four commercial activated carbons with different chemical and textural characteristics were modified by gamma irradiation under five different conditions: irradiated in absence of water, in presence of ultrapure water, in ultrapure water at pH = 1.0 and 1000 mg L−1 Cl−, in ultrapure water at pH = 7.5 and 1000 mg L−1 Br−, and in ultrapure water at pH = 12.5 and 1000 mg L−1 NO3−. Changes in surface chemistry were studied by X-ray photoelectron spectroscopy; pH of point of zero charge, total acidic groups and total basic groups, which were determined by assessment with HCl and NaOH; and textural changes were determined by obtaining the corresponding adsorption isotherms of N2 and CO2. Outcomes show that the activated carbon surface chemistry can be modified by gamma irradiation and that the changes depend on the irradiation conditions. Modifications in the sp2 hybridization of the surface carbons suggest that the irradiated carbons undergo graphitization. Measurements of structural parameters indicate that the irradiation treatment does not modify the textural properties of the carbons. Finally, studies of pristine and irradiated activated carbons using diffuse reflectance spectroscopy with the Kubelka–Munk function revealed a reduction in band gap energy in the irradiated carbons associated with an increase in sp2 hybridization of the carbon atoms.
    Carbon 02/2014; 67:236–249. DOI:10.1016/j.carbon.2013.09.087 · 6.16 Impact Factor
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    ABSTRACT: The objective of this study was to analyze the influence of the presence of activated carbon on the degradation of the triiodinated contrast medium diatrizoate (DTZ) by the simultaneous use of gamma radiation and activated carbon. Four commercial activated carbons (Ceca, Witco, Sorbo, and Merck) with different textural and chemical characteristics were used for this purpose. The percentage DTZ removal obtained was considerably higher with the gamma radiation/activated carbon (GM/AC) system than with radiolysis in the absence of activated carbon, and it depended on the specific activated carbon employed. First, we optimized the amount of activated carbon required to maximize the amount of DTZ removed by the GM/AC system (0.06 g). The degradation constants were higher with the GM/AC system than with radiolysis alone, evidencing a synergic effect that favors pollutant removal. This synergic effect is independent of the textural but not the chemical characteristics of the activated carbon, observing a higher synergic activity for carbons with a higher surface content of oxygen, specifically quinone groups. We also highlight that the synergic effect of the activated carbon requires adsorbent–adsorbate electrostatic interaction and is absent when this interaction is hindered.
    Carbon 02/2014; 67:288–299. DOI:10.1016/j.carbon.2013.09.091 · 6.16 Impact Factor
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    ABSTRACT: The objective of this study was to analyze the behavior of activated carbons with different chemical and textural natures in the adsorption of three tetracyclines (TCs) (tetracycline, oxytetracycline, and chlortetracycline). We also assessed the influence of the solution pH and ionic strength on the adsorption of these compounds and studied their removal by the combined use of microorganisms and activated carbon (bioadsorption). Sludge-derived materials were also used to remove TC from water. The capacity of these materials to adsorb TC was very high and was much greater than that of commercial activated carbon. This elevated adsorption capacity (512.1-672.0 mg/g) is explained by the high tendency of TC to form complex ions with some of the metal ions present in these materials. The medium pH and presence of electrolytes considerably affected TCs adsorption on commercial activated carbon. These results indicate that electrostatic adsorbent-adsorbate interactions play an important role in TC adsorption processes when conducted at pH values that produce TC deprotonation. The presence of bacteria during the TCs adsorption process decreases their adsorption/bioadsorption on the commercial activated carbon, weakening interactions between the adsorbate and the microfilm formed on the carbon surface. The adsorptive capacity was considerably lower in dynamic versus static regime, attributable to problems of TC diffusion into carbon pores and the shorter contact time between adsorbate and adsorbent.
    Journal of Environmental Management 10/2013; 131C:16-24. DOI:10.1016/j.jenvman.2013.09.024 · 3.19 Impact Factor
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    ABSTRACT: The main objective of this study was to identify the origin of the photocatalytic behavior of activated carbons in the presence of ultraviolet (UV) light. For this purpose, we selected four commercial activated carbons and sixteen gamma radiation-modified carbons derived from these. Sodium diatrizoate was considered as model compound for the degradation study. The results demonstrate that the direct diatrizoate photodegradation rate is influenced by the solution pH. The presence of activated carbon during diatrizoate degradation markedly accelerates its rate of removal, regardless of the activated carbon used. Witco commercial carbon exerts the highest synergic effect in diatrizoate removal by the UV/activated carbon system, with a synergic contribution >53% after the first minute of treatment. The synergic activity of all of the activated carbon samples is enhanced by gamma radiation treatment. The textural properties of the activated carbons show no clear relationship with their synergic contribution. However, the synergic activity of the activated carbon is more greatly enhanced in the samples with higher percentages of surface oxygen, and among these, the samples with higher percentages of ester/anhydride groups and of carbon atoms with sp(2) hybridization. Band gap (E-g) determination of activated carbons revealed that they behave as semiconductor materials and, therefore, as photoactive materials in the presence of UV radiation, given that all E-g values are <4 eV. We also observed that the gamma radiation treatment reduces the band gap values of the activated carbons and that, in a single series of commercial carbons, lower E-g values correspond to higher sodium diatrizoate removal rate values. We highlight that the gamma radiation-modified materials show a higher percentage of carbon atoms with sp(2) hybridization, explaining their superior behavior in the process. Finally, we observed that: (i) the activity of the reutilized activated carbons is similar to that of the original carbons, (ii) the presence of dissolved oxygen enhances the rate of diatrizoate removal by UV/activated carbon, and (iii) the UV radiation treatment produces slight chemical modifications in the activated carbons. Based on these results, an action mechanism for the photocatalytic removal of diatrizoate in the presence of activated carbon is proposed, in which the activated carbon acts as a photocatalyst, promoting electrons of the valence band to the conduction band and increasing the generation of HO center dot radicals in the medium. (c) 2013 Elsevier B.V. All rights reserved.
    Applied Catalysis B Environmental 10/2013; 142-143:694-704. DOI:10.1016/j.apcatb.2013.06.003 · 6.01 Impact Factor
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    ABSTRACT: In planning treatment for each new patient, radiation oncologists pay attention to the aspects that they control. Thus their attention is usually focused on volume and dose. The dilemma for the physician is how to protract the treatment in a way that maximizes control of the tumour and minimizes normal tissue injury. The initial radiation-induced damage to DNA may be a biological indicator of the quantity of energy transferred to the DNA. However, until now the biophysical models proposed cannot explain either the early or the late adverse effects of radiation, and a more general theory appears to be required. The bystander component of tumour cell death after radiotherapy measured in many experimental works highlights the importance of confirming these observations in a clinical situation.
    Cancer letters 09/2013; 356(1). DOI:10.1016/j.canlet.2013.09.006 · 5.02 Impact Factor
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    ABSTRACT: We have investigated the capacity of activated carbon cloth to support the growth and differentiation of human mesenchymal umbilical-cord stromal stem cells. Our results demonstrate that this scaffold provides suitable conditions for the development of cell-derived matrix proteins and facilitates the growth of undifferentiated stem cells with the ability to induce osteogenic and chondrogenic differentiation. Immunoflourescence staining revealed extensive expression of collagen in all the samples, and collagen type II and osteopontin within the samples cultivated in specific differentiation-inducing media. Cell growth and the formation of natural collagen, calcium–magnesium carbonate and hydroxyapatite crystals, together with the self-assemblage of collagen to produce suprafibrillar arrangements of fibrils all occur simultaneously and can be studied together ex vivo under physiological conditions. Furthermore, the spontaneous differentiation of stem cells cultured on activated carbon cloth with no osteogenic supplements opens up new possibilities for bone-tumour engineering and treatment of traumatic and degenerative bone diseases.
    06/2013; 1(27):3359-3368. DOI:10.1039/C3TB20305K
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    ABSTRACT: Background This study analyzes the efficacy of a gamma radiation advanced oxidation/reduction process (AORP) to treat waters contaminated with the antibiotics tetracycline (TC), chlortetracycline (CTC), and oxytetracycline (OTC). ResultsStudy results indicate that: (1) radiolysis of the three TCs fits a pseudo-first-order kinetic model in which the radiation-chemical yield decreases with higher absorbed dose; (2) the value of the dose constant depended on the dose rate, which ranged from 3.83 to 1.66 Gy min–1, and depended to a small extent on the medium pH between pH values of 2.0 and 10.0, since aqueous electrons and hydroxyl radicals both act in TC degradation; (3) the effectiveness of the process was slightly increased at low concentrations of H2O2; (4) the presence of Cl−, , , and humic acid influenced TCs degradation, which was higher at low concentrations of Cl−, and HA and markedly decreased at low concentrations of of and ; (5) the dose constant is lower in natural waters; (6) TOC values for ultrapure water, surface water, groundwater and wastewater showed that it is not possible to obtain complete TC mineralization at the absorbed doses; (7) the toxicity of byproducts formed during the radiolytic process was lower. Conclusions Gamma radiation, an oxidation/reduction procedure, is an effective treatment for removing TC, CTC and OTC from aqueous solutions. TC degradation takes place by both oxidation and reduction pathways, with a predominance of the latter, as demonstrated by the markedly reduced dose constant in the presence of aqueous electron scavengers.
    Journal of Chemical Technology & Biotechnology 06/2013; 88(6). DOI:10.1002/jctb.3946 · 2.49 Impact Factor
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    ABSTRACT: The elimination of diphenolic acid (DPA) from contaminated water is an urgent challenge. The aim of this study was to investigate DPA degradation by gamma radiation, studying the influence of the dose rate, initial DPA concentration, solution pH, the presence of O2, and the presence of different additives (e.g., Br�, Cl�, CO2�; NO3 ; NO�2 ; and SO24 ). A further objective was to study the effect of the water matrix (ultrapure water, surface water, and wastewater) and the variation in total organic carbon and toxicity as a function of absorbed dose. Results obtained showed that: gamma radiation was effective to remove DPA from aqueous solution; the dose constant was slightly dependent on the dose rate; and the solution pH had a major influence on DPA degradation, which was highest at pH 7. DPA degradation was reduced in the presence of Br�, Cl�, CO2�; NO3; NO2; and SO24 and was lower with higher concentrations of these species, largely due to their competition with DPA for the reactive radicals generated, especially HO�. Lower yield of DPA decomposition were obtained with wastewater and surface water than with ultrapure water due to the presence of organic matter and HCO�3 ; Cl�; SO24 ; and NO�3 ions, which react with the reactive radical species (HO�, H� and e�aq). The TOC and toxicity of the medium decreased during DPA degradation in all water types studied.
    Chemical Engineering Journal 01/2013; 219(1):371-379. DOI:10.1016/j.cej.2012.12.069 · 4.32 Impact Factor
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    ABSTRACT: h i g h l i g h t s " The first-order kinetic fits tetracycline (TC) adsorption on sludge adsorbents. " The rate constants vary in a linear manner with their macro-and mesopore volumes. " The TC adsorption rate on all adsorbents is controlled by intraparticle diffusion. " Pore volume diffusion represents more than 80% of the total intraparticle diffusion. " Diffusion of TC in the pore volume increases with larger meso and macropore volume. a b s t r a c t This study investigated the global adsorption rate of tetracycline on adsorbents obtained from treatment sludge. Experimental data on tetracycline concentration decay curves were interpreted with kinetic mod-els (first-order, second-order, Langmuir, and intraparticle diffusion) and diffusional models (pore volume diffusion model and surface diffusion model). The first-order kinetic model provided the best interpreta-tion of tetracycline adsorption kinetics on all adsorbents, and its rate constant varied in a linear manner the macro-and mesopore volume of the adsorbents. It was also found that the tetracycline adsorption rate is controlled by intraparticle diffusion and that diffusion in the pore volume represents >80% of total intraparticle diffusion. This indicates that surface diffusion does not play a major role in tetracycline dif-fusion on the different adsorbents. Furthermore, the effective tetracycline diffusion coefficient in the pore volume gradually increased with greater meso-and macropore volume and larger surface area of the adsorbent, indicating that the tetracycline adsorption rate is directly related to the accessibility of this molecule to the microporous structure of the materials. Ó 2012 Elsevier B.V. All rights reserved.
    The Chemical Engineering Journal 11/2012; 213:88–96. DOI:10.1016/j.cej.2012.09.072
  • European Journal of Cancer 11/2012; 48:138. DOI:10.1016/S0959-8049(12)72242-6 · 4.82 Impact Factor
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    ABSTRACT: The objective of this study was to analyze the effectiveness of gamma irradiation to transform diatrizoate, DTZ, (contrast medium) in aqueous solution determining the role of oxidizing and reducting species on DTZ degradation. The mechanisms involved in DTZ degradation have also been studied. Removal of 91.9% of the diatrizoate was achieved at a dose of 1000 Gy at initial concentration of 25 mg/L. The degradation rate depends on the initial concentration. The dose constant is independent of the dose rate in the studied range of 3.83–1.06 Gy/min and slightly depends on solution pH in the interval pH 2.0–10.0. Results obtained show that low H2O2 concentrations increase the efficacy of the process, and high concentrations markedly decrease the dose constant. The reaction constant of diatrizoate with the hydrogen radical was determined, obtaining a kHkH (DTZ) value of (2.2 ± 0.5) × 109 M−1 s−1. DTZ irradiation by-products have been determined by HPLC-MS and an oxidation/reduction mechanism has been proposed. Three possible degradation pathways based on the major byproducts found at different doses have been proposed. Moreover, the results obtained indicated a further possible compound degradation pathway, which is based on decarboxylation by hydrogen radical or HO· radical with a subsequent attack by hydroxyl radicals against the ketone group.
    Chemical Engineering Journal 07/2012; s 195–196:369–376. DOI:10.1016/j.cej.2012.04.046 · 4.32 Impact Factor
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    ABSTRACT: The objective of this study was to analyze the effectiveness of medium-pressure I imps in the direct and indirect photodegradation of tetracyclines (TCs). We conducted a kinetic study of the process, determining the quantum yield for three tetracyclines (tetracycline, chlorotetracycline and oxytetracycline). We also analyzed the influence of different operational variables, such as: initial concentration; solution pH; presence of natural organic matter (NOM); the chemical composition of water, using ultrapure water (UW), surface water (SW), groundwater (GW), and wastewater (WW); the behavior of total organic carbon (TOC) concentration, and the system toxicity during TCs photodegradation The results obtained shown that medium-pressure mercury lamp radiation is effective for the photooxidation of TCs in aqueous phase, mainly when these are at low concentrations. The rate constants obtained indicate that the photodegradation is pH-dependent and favored at pH 10 regardless of the tetracycline considered. The presence of H2O2 in the medium substantially increased the TC degradation rate and considerably reduced the time required to degrade 100% of the initial TC concentration. The TC photooxidation rate was higher in natural waters than in ultrapure water, attributable to the presence of dissolved organic matter, which can act as a photosensitizer, thereby favoring indirect TC degradation through the formation of radical species such as HO center dot. TOC values at the end of the treatment indicated that the percentage mineralization is a function of the initial TC concentration. The medium toxicity increased at the beginning of TC photooxidation, and treatment times of around 60 min are generally required for the toxicity to be lower than in the original solution.
    Chemical Engineering Journal 04/2012; DOI:10.1016/j.cej.2012.01.096 · 4.32 Impact Factor
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    ABSTRACT: The objective of this study was to optimize the preparation of treatment plant wastewater sludge adsorbents for application in water treatment. The optimal adsorption capacity was obtained with adsorbents prepared by pyrolysis at 700°C for 3h. We studied the effect of binder type on the adsorbents, finding that their textural properties were not substantially affected by the addition of phenolic resins but their surface area was reduced by the presence of clayey soil. Analysis of the composition of surface groups in these materials revealed: (i) a high concentration of basic surface groups in non-activated pyrolyzed sludge, (ii) an increase in the concentration of basic surface groups after chemical activation, (iii) no modification in the concentration of carboxyl or basic groups with the addition of binding agent before the activation, and (iv) total disappearance of carbonyl groups from sample surfaces with the addition of humic acid or clayey soil as binder. All these adsorbents had a low C content. The capacity of these sludge-derived materials to adsorb methylene blue, 2,4-dichlorophenol, tetracycline, and (Cd(II)) was studied. Their adsorption capacity was considerably increased by the chemical activation but reduced by the pre-activation addition of a binding agent (humic acid, phenolic resin, and clayey soil).
    Journal of hazardous materials 03/2012; 217-218:76-84. DOI:10.1016/j.jhazmat.2012.02.067 · 4.33 Impact Factor
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    ABSTRACT: To examine direct and bystander radiation-induced effects in normal umbilical-cord stromal stem cell (HCSSC) lines and in human cancer cells. The UCSSC lines used in this study were obtained in our laboratory. Two cell lines (UCSSC 35 and UCSSC 37) and two human melanoma skin-cancer cells (A375 and G361) were exposed to ionizing radiation to measure acute radiation-dosage cell-survival curves and radiation-induced bystander cell-death response. Normal cells, although extremely sensitive to ionizing radiation, were resistant to the bystander effect whilst tumor cells were sensitive to irradiated cell-conditioned media, showing a dose-response relationship that became saturated at relatively low doses. We applied a biophysical model to describe bystander cell-death through the binding of a ligand to the cells. This model allowed us to calculate the maximum cell death (χ(max)) produced by the bystander effect together with its association constant (K(By)) in terms of dose equivalence (Gy). The values obtained for K(By) in A375 and G361 cells were 0.23 and 0.29 Gy, respectively. Our findings help to understand how anticancer therapy could have an additional decisive effect in that the response of sub-lethally hit tumor cells to damage might be required for therapy to be successful because the survival of cells communicating with irradiated cells is reduced.
    Radiotherapy and Oncology 12/2011; 102(3):450-8. DOI:10.1016/j.radonc.2011.11.002 · 4.86 Impact Factor
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    ABSTRACT: The aim of this study was to determine the effectiveness of gamma radiation to degrade cytarabine in aqueous solution. The effect of dose rate, initial cytarabine concentration, medium pH, and the presence of H2O2, Cl-, CO32-, NO3-, NO2- and organic matter was studied. Furthermore, the influence of the chemical composition of water on cytarabine degradation was evaluated by using different water matrix (ultrapure water, surface water, groundwater, and wastewater) and the variations in total organic carbon concentration and toxicity were also studied. Results show that cytarabine radiolysis fits pseudo-first order kinetics. The dose constants determined in this study ranged from 0.002 x 10(-2) to 1.32 x 10(-2) Gy(-1), whereas the initial radiation-chemical yield ranged from 0.033 to 0.94 mu mol J(-1). Cytarabine degradation in the presence of Cl-, CO32-, NO3-, NO2- and humic acid showed a decrease in dose constants with the increase in present species concentration, largely due to competition of cytarabine with Cl-, CO32-, NO3-, NO2- and humic acid by the reactive species generated, mainly HO center dot radicals. Cytarabine degradation was slightly improved by the presence of small amounts of H2O2, which acted as promoter of HO center dot radicals. However, the dose constant decreased at high concentrations of H2O2 (concentrations above 1 mM) due to inhibition of HO center dot radicals by recombination reactions. The effectiveness of gamma radiation was markedly reduced in wastewater due to inhibition of the reactive species by the high organic matter and anion content of the water. This study shows that it is not possible to completely mineralize organic matter in ultrapure water, surface water, groundwater, or wastewater at the radiation closes used
    Chemical Engineering Journal 10/2011; 174(1):1-8. DOI:10.1016/j.cej.2011.07.017 · 4.32 Impact Factor
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    ABSTRACT: The main objectives of this study were: (1) to investigate the decomposition and mineralization of nitroimidazoles (Metronidazole [MNZ], Dimetridazole [DMZ], and Tinidazole [TNZ]) in waste and drinking water using gamma irradiation; (2) to study the decomposition kinetics of these nitroimidazoles; and (3) to evaluate the efficacy of nitroimidazole removal using radical promoters and scavengers. The results obtained showed that nitroimidazole concentrations decreased with increasing absorbed dose. No differences in irradiation kinetic constant were detected for any nitroimidazole studied (0.0014-0.0017 Gy(-1)). The decomposition yield was higher under acidic conditions than in neutral and alkaline media. Results obtained showed that, at appropriate concentrations, H(2)O(2) accelerates MNZ degradation by generating additional HO(); however, when the dosage of H(2)O(2) exceeds the optimal concentration, the efficacy of MNZ degradation is reduced. The presence of t-BuOH (HO() radical scavenger) and thiourea (HO(), H() and e(aq)(-) scavenger) reduced the MNZ irradiation rate, indicating that degradation of this pollutant can take place via two pathways: oxidation by HO() radicals and reduction by e(aq)(-) and H(). MNZ removal rate was slightly lower in subterranean and surface waters than in ultrapure water and was markedly lower in wastewater. Regardless of the water chemical composition, MNZ gamma irradiation can achieve i) a decrease in the concentration of dissolved organic carbon, and ii) a reduction in the toxicity of the system with higher gamma absorbed dose.
    Water Research 06/2009; 43(16):4028-36. DOI:10.1016/j.watres.2009.05.033 · 5.32 Impact Factor
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    ABSTRACT: The main objective of this study was to analyze the effectiveness of technologies based on the use of ozone, gamma irradiation and activated carbon for the removal of nitroimidazoles (metronidazole (MNZ), dimetridazole (DMZ), tinidazole (TNZ), ronidazole (RNZ)) from water, considering them as model compounds of pharmaceuticals. Results indicate that the adsorption of nitroimidazoles on activated carbon is largely determined by activated carbon chemical properties. Application of the Langmuir equation to the adsorption isotherms showed an elevated adsorption capacity (Xm = 1.04-2.04 mmol/g) for all contaminants studied. Nitroimidazoles are not degraded by microorganisms used in the biological stage of a wastewater treatment plant. However, the presence of microorganisms during nitroimidazole adsorption increased their adsorption/bioadsorption on the activated carbon, although it weakened interactions between the adsorbate and carbon surface. Ozone reaction kinetics showed that nitroimidazoles have a low reactivity, with k O 3 values < 350 M -1 s -1 regardless of the nitroimidazole and solution pH considered. However, nitroimidazoles have a high affinity for HO· radicals, with radical rate constant (k HO) Removal of nitroimidazole antibiotics from water by adsorption/bioadsortion on activated carbon and advanced oxidation processes values of around 10 10 M -1 s -1 . The presence of activated carbon during nitroimidazole ozonation produces: i) an increase in the removal rate, ii) a reduction in the toxicity of oxidation by-products, and iii) a reduction in the concentration of dissolved organic matter. When using gamma irradiation to degradate nitroimidazoles, no differences in constant rates were detected for any nitroimidazole studied (0.0014 -0.0017 Gy -1). The presence of t-BuOH (HO· radical scavenger) and thiourea (HO·, H· and e -aq scavenger) reduced the MNZ irradiation rate, indicating that degradation of this pollutant can take place via two pathways: oxidation by HO· radicals and reduction by e -aq and H·. MNZ gamma irradiation can achieve i) a decrease in the concentration of dissolved organic carbon, and ii) a reduction in the toxicity of the system with higher gamma absorbed dose.

Publication Stats

121 Citations
78.72 Total Impact Points

Institutions

  • 2008–2015
    • University of Granada
      • • Department of Inorganic Chemistry
      • • Faculty of Science
      • • Instituto de Biopatología y Medicina Regenerativa (IBIMER)
      Granata, Andalusia, Spain
  • 2014
    • Hospital Universitario Virgen de las Nieves
      Granata, Andalusia, Spain