Person: Lorenzo Fernández, David
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First Name
David
Last Name
Lorenzo Fernández
Affiliation
Universidad Complutense de Madrid
Faculty / Institute
Ciencias Químicas
Department
Ingeniería Química y de Materiales
Area
Ingeniería Química
Identifiers
18 results
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Now showing 1 - 10 of 18
Item Comparison of real wastewater oxidation with Fenton/Fenton-like and persulfate activated by NaOH and Fe(II)(Journal of Environmental Management, 2020) Rodríguez Vega, Sergio; Lorenzo Fernández, David; Santos López, Aurora; Romero Salvador, ArturoTreatment of polluted wastewaters from industrial activities has become a source of major concern for the environment. In this work, real wastewater from a physico-chemical (WWFQ) treatment was tested through different oxidation technologies: Fenton and Fenton-like reagent and persulfate activated by NaOH and Fe(II). Oxidation reactions with Fenton's reagent were carried out in a 0.25 L batch reactor at 25 °C by adding either Fe(II) or Fe(III) and H2O2 to an aqueous solution of wastewater, whose pH was previously adjusted to 2 or 3. Iron concentration ranging from 25 to 100 mg/L and peroxide concentration from 2500 to 10000 mg/L were used. The total organic carbon slightly decreased when WWFQ was treated. Moreover, better results were obtained when Fe(II) was used than Fe(III). Both iron concentration and oxidant dosage had a positive influence on the chemical oxygen demand (COD) removal, until an asymptotic value of 30% was obtained. Oxidation of pollutants contained in WWFQ was studied with persulfate (18.4–294 mM) activated with NaOH and Fe(II) (36.8–588 mM). Again, a positive influence of both persulfate and NaOH was observed, although a similar asymptotic COD value was observed. This parallelism between both technologies confirms recalcitrant compounds were obtained.Item Abatement of chlorinated compounds in groundwater contaminated by HCH wastes using ISCO with alkali activated persulfate(Science of The Total Environment, 2018) Santos López, Aurora; Jesús Fernández; Rodríguez Vega, Sergio; Domínguez Torre, Carmen María; Miguel Ángel Lominchar; Lorenzo Fernández, David; Romero Salvador, ArturoIn this work, in situ chemical oxidation (ISCO) with alkali activated persulfate has been tested for the elimination of HCH isomers and other chlorinated compounds in groundwater from Sabiñanigo (Sardas landfill), which was contaminated by solid and liquid wastes illegally dumped in the area by a company producing lindane. Due to the site lithology and the type of pollutants found in groundwater (HCHs and chlorobenzenes) alkali (NaOH) activated persulfate (PS) was selected as oxidant. The influence of variables such as PS concentration (42–200 mM) and NaOH:PS molar ratio (2:1 to 4:1) on chlorinated compound abatement has been studied and a kinetic model to predict the composition of all chlorinated organic compounds (COCs) in the aqueous phase with time was obtained. It was found that a fast initial hydrodechlorination reaction took place in which HCH isomers reacted to trichlorobenzenes (mainly 1,2,4 TCB) at pH ≥ 12. Mono-, di-, tri and tetrachlorobenzenes remaining were oxidized without producing aromatic intermediates. At the condition tested a first order kinetic model for COCs and PS concentration was obtained. Zero order alkali concentration was obtained while pH was being kept at 12 for the whole reaction time.Item Using Two Group-Contribution Methods to Calculate Properties of Liquid Compounds Involved in the Cyclohexanone Production Operations(liquids, 2022) Fernández, Luis; Ortega, Juan; Dominguez, Leandro; Lorenzo Fernández, David; Santos López, Aurora; Romero Salvador, ArturoA numerical application has been carried out to determine the thermophysical properties of more than fifty pure liquid compounds involved in the production process of cyclohexanone, whose real values are unknown, in many cases. Two group-contribution methods, the Joback and the Marrero–Gani methods, both used in the fields of physicochemistry and engineering, are employed. Both methods were implemented to evaluate critical properties, phase transition properties, and others, which are required for their use in industrial process simulation/design. The quality of the estimates is evaluated by comparing them with those from the literature, where available. In general, both models provide acceptable predictions, although each of them shows improvement for some of the properties considered, recommending their use, when required.Item Selective removal of chlorinated organic compounds from soil flushing emulsions: Adsorbent regeneration with thermal-activated persulfate and surfactant recovery(Journal of Water Process Engineering, 0202) Sánchez Yepes, Andrés; Santos López, Aurora; Romero Salvador, Arturo; Lorenzo Fernández, DavidHydrophobic organic compounds (HOCs) released into the environment can form nonaqueous phase liquids, contaminating soil and groundwater. Surfactant-enhanced aquifer remediation, followed by extracting a highly contaminated emulsion comprising surfactants and contaminants, is a promising technology for remediating polluted sites. However, the sustainable treatment of the emulsion is crucial. This study presents a two-step method for treating emulsions containing HOCs and surfactants. Firstly, pollutants are selectively adsorbed onto granular activated carbon (GAC) in a column. Secondly, spent GAC is regenerated by oxidizing adsorbed pollutants using persulfate activated at 60 ◦C. The emulsion was obtained from surfactant-enhanced aquifer remediation at a polluted site with lindane production waste, consisting of E-Mulse® 3 surfactant (12 g L− 1 ) and 28 chlorinated organic compounds (COCs) at a concentration of 9.1 gCOCs L− 1 . Selective adsorption of COCs was observed since the adsorption kinetic constant was much higher than the E3, being 31.60 and 1.76 gGAC− W⋅mg− 1 j ⋅ h− 1 respectively. The adsorption-regeneration cycle was repeated three times. It was found that the GAC adsorbed 90 mgCOCs⋅gGAC − 1 were constant after four cycles (70 % of the COCs adsorption capacity in the first step). The surfactant adsorption decreased by approximately 80 % from 108 to 26 mgE3 gGAC − 1 after the third cycle, enabling surfactant recovery from the emulsion. In addition, the remaining amount of persulfate increased from 24 to 39 %, reducing oxidant consumption. Finally, the water effluent obtained after regeneration showed reduced toxicity due to the generation of nontoxic by-products, such as short-chain acids and sulphates. The results obtained proved the GAC-based adsorption/regeneration process was effective and stable over multiple cycles.Item Chlorinated organic compounds in liquid wastes (DNAPL) from lindane production dumped in landfills in Sabiñanigo (Spain)(Environmental Pollution, 2018) Santos López, Aurora; Jesús Fernández; Joaquín Guadaño; Lorenzo Fernández, David; Romero Salvador, Arturoα β and γ-hexachlorocyclohexane (HCH) are persistent and bioaccumulative pollutants and they were included in the Stockholm Convention on Persistent Organic Pollutants (POPs). Old lindane factories generated high amounts of wastes with HCH and other Chlorinated Organic Compounds (COCS). These were often dumped in the surroundings of the production sites, polluting soil and groundwaters with the associated risk of surface pollution. This is the case of the Sardas and Bailin landfills, located in Sabiñánigo (Huesca, Spain). Among the waste from lindane production, a liquid residue was detected in the landfill subsurfaces, forming a dense non-aqueous phase liquid (DNAPL) composed of HCH isomers, benzene and chlorobenzenes, with a high impact on groundwater pollution. In this study, six DNAPL samples obtained from the Bailin and Sardas landfills were analyzed by GC/MSD and GC/FID/ECD. Compounds were identified using mass spectra and the retention index from pure standards and literature information. Pure positional isomers of dichlorobenzene (DCB), trichlorobenzene (TCB), tetrachlorobenzene (TetraCB), HCH and pentachlorocyclohexene (PentaCX) were distinguished and quantified. In addition, heptachlorocyclohexane (HeptaCH) isomers, precursors of hexacholorocylohexene (HexaCX), were also identified and quantified in the DNAPL samples, although the corresponding isomers could not be discriminated. Information about PentaCX, HexaCx and HeptaCH identification is very limited in the literature. HCH contents in the DNAPL ranged from 22% to 30% in weight, the major isomers being lindane and δ-HCH, followed by α-HCH. The β isomer was the least abundant. HeptaCH contents were present in the same order of magnitude as HCHs in the DNAPL. PentaCXs and HexaCXs could have appeared as dehydrochlorination derivatives of HCHs and HeptaCHs, respectively. Two of the DNAPLs analyzed showed a higher content of TCBs and TetraCBs, associated with lower HCH and HeptaCH contents. Variations of these compounds in the DNAPL could be related to an alkaline dehydrochlorination in the landfill conditions. Six DNAPL samples, as waste disposal from lindane production, obtained from Sabiñánigo landfills (Huesca, Spain) have been fully characterized, quantifying and identifying twenty-eight Chlorinated Organic Compounds, from chlorobenzene to heptachlorocyclohexane.Item Kinetic of Alkali Catalyzed Self-Condensation of Cyclohexanone(Industrial & Engineering Chemistry Research, 2013) Lorenzo Fernández, David; Santos López, Aurora; Simón Camacho, Ernesto; Romero Salvador, ArturoItem Partitioning of chlorinated organic compounds from dense non-aqueous phase liquids and contaminated soils from lindane production wastes to the aqueous phase(Chemosphere, 2019) Lorenzo Fernández, David; García Cervilla, Raúl; Santos López, Aurora; Romero Salvador, ArturoHexachlorocyclohexane (HCH) and mainly the g-HCH isomer, namely lindane, were extensively produced and used as pesticides. Huge amounts of wastes, solids and liquids, were disposed of in the surroundings of the production sites. The liquid residuum was a complex mixture of chlorinated organic compounds, COCs, from chlorobenzene to heptachlorocyclohexane. This Dense Non-Aqueous Phase Liquid, DNAPL, migrated by density through the subsurface to greater depths, being trapped or adsorbed into the soil in this movement posing a significant risk to the groundwater. Knowledge of the partitioning in water of COCs in DNAPL is a key issue to determine its fate in the environment. However, there are no data in literature for the partitioning and/or solubility of many of the COCs in this DNAPL, such as pentachlorocyclohexene, hexachlorocyclohexene and heptachlorocyclohexane despite them constitute about 13e30% of the mole fraction of the DNAPLs. In this work, the partitioning to water of COCs in free and those adsorbed onto soil has been studied. In addition, measured and predicted aqueous concentrations of each COC in the DNAPL mixture have been compared. To do this, the solubility of a compound that is a solid crystal when pure at P ¼ 298 K and P ¼ 1 atm has been evaluated considering the approach of sub-cooled liquid state of solid organochlorines. Samples were obtained at Sabinanigo land ~ fills and soils used had several grain sizes. Transformation in alkaline media of COCs had a positive environmental impactItem Thermally activated persulfate for the chemical oxidation of chlorinated organic compounds in groundwater(Journal of Environmental Management, 2020) Domínguez Torre, Carmen María; Romero Salvador, Arturo; Lorenzo Fernández, David; Santos López, AuroraChlorinated pesticides were extensively produced in the XX century, generating high amounts of toxic wastes often dumped in the surroundings of the production sites, resulting in hot points of soil and groundwater pollution worldwide. This is the case of Bailín landfill, located in Sabiñánigo (Spain), where groundwater is highly polluted with chlorobenzenes (mono, di, tri and tetra) and hexachlorocyclohexanes. This study addresses the abatement of chlorinated organic compounds (COCs) present in the groundwater coming from the Bailín landfill by thermally activated persulfate, PS (TAP). The influence of temperature (30–50 °C) and oxidant concentration (2–40 g L−1) on the efficiency of COCs (initial concentration of COCs = 57.53 mg L−1, determined by the solubility of the pollutants in water) degradation has been investigated. Raising the reaction temperature and PS concentration the degradation of COCs significantly accelerates, as a result of higher production of sulfate radicals. The thermal activation of PS implies side reactions, involving the unproductive decomposition of this oxidant. The activation energy calculated for this reaction (128.48 kJ mol−1) reveals that is slightly more favored by temperature than the oxidation of COCs by sulfate radicals (102.4–115.72 kJ mol−1). At the selected operating conditions (PS = 10 g L−1, 40 °C), the almost complete conversion of COCs and a dechlorination and mineralization degree above 80% were obtained at 168 h reaction time. A kinetic model, able to adequately predict the experimental concentration of COCs when operating at different temperatures and initial concentration of PS has been proposed.Item Kinetic model of 2-cyclohexenone formation from cyclohexanol and 2-cyclohexenol dehydrogenation(Chemical Engineering Journal, 2012) Simón Camacho, Ernesto; Pardo Pardo, Fernando; Lorenzo Fernández, David; Santos López, Aurora; Romero Salvador, ArturoIn this study, a kinetic model (including reaction scheme and the kinetic parameters) for formation reactions of dehydrogenation impurities (2-cyclohexenone and phenol) was developed for the cyclohexanol and 2-cyclohexenol dehydrogenation processes. 2-Cyclohexenol used to be an impurity contained in commercial cyclohexanol. Runs were carried out at 250 and 290 °C in a fixed bed reactor using a Cu–Zn catalyst. It was found that 2-cyclohexenol quickly produces 2-cyclohexenone and other dehydration impurities, and 2-cyclohexenone rapidly reverts to cyclohexanone in the presence of hydrogen. Phenol formed from high amounts of cyclohexanone and hydrogen is mainly produced by the direct reaction of cyclohexanone. In the caprolactam manufacturing process, cyclohexanone is mostly produced by cyclohexanol dehydrogenation. Using Cu–Zn catalysts, as in this study, phenol is obtained as the main impurity, at high concentrations and formed from cyclohexanone. However, 2-cyclohexenone was also found as a dehydrogenation impurity. This compound can produce unsaturated lactam in the caprolactam production from cyclohexanone that considerably decreases the quality of nylon. Therefore, 2-cyclohexenone can be produced from cyclohexanone or 2-cyclohexenol. In turn, phenol can originate directly from cyclohexanone dehydrogenation or from 2-cyclohexenone dehydrogenation in a serial reaction process.Item Degradation of Hexachlorocyclohexanes (HCHs) by Stable Zero Valent Iron (ZVI) Microparticles(Water, Air, & Soil Pollution, 2016) Domínguez Torre, Carmen María; Rodríguez Vega, Sergio; Lorenzo Fernández, David; Romero Salvador, Arturo; Santos López, AuroraDuring the production of lindane (γ-HCH) large volumes of wastes containing α-, β-, and δ-HCH isomers were generated. Hexachlorocyclohexanes (HCHs) are carcinogens and teratogen compounds. Although their production and use are currently banned in most countries, many landfills and sites remain polluted by these compounds. This paper studies a promising and novel alternative for the HCH abatement: dechlorination by zero valent iron microparticles. Synthetic wastewater (0.5 mg/L of α-, β-, γ-, and δ-HCH or 6 mg/L of γ-HCH) and five types of commercial iron microparticles (here named mFe-1, mFe-2, mFe-3, mFe-4, and mFe-5) were used in batch (5 g/L) and continuous (W mFe/Q L = 167 g · h/L) operation mode at room temperature. Iron microparticles were characterized (before and after reaction) by N2 adsorption/desorption isotherms and X-ray diffraction. HCH isomers showed different behavior vs. dechlorination (γ > α > δ > β) according to the axial/equatorial position of the chlorines. The most active iron source among those tested was mFe-1, presenting small particle diameter (70 μm), moderate BET area (35 m2/kg), low oxygen content, and traces of manganese. mFe-1 exhibited high activity and stability both in continuous (X γ-HCH = 70%, W mFe/Q L = 167 g · h/L) and discontinuous (X γ-HCH = 100%, 48 h) operation. Contribution of HCH adsorption over iron microparticles was found negligible being benzene and Cl− the final dechlorination products.