Person: Lorenzo Fernández, David
Loading...
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
5 results
Search Results
Now showing 1 - 5 of 5
Item 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 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.Item Kinetics of lindane dechlorination by zero valent iron microparticles: Effect of different salts and stability study.(Industrial and Engineering Chemistry Research, 2016) Domínguez Torre, Carmen María; Santos López, Aurora; Parchão, Joana; Rodríguez Vega, Sergio; Lorenzo Fernández, David; Romero Salvador, ArturoThis report is focused on the dechlorination of lindane, a recalcitrant and refractory pollutant, by zerovalent iron microparticles (ZVIM) in batch and continuous mode. Experimental variables such as initial lindane concentration, ZVIM dosage, and temperature were studied. Batch experiments indicate that the lindane dechlorination is enhanced with the increase of ZVIM dosage and reaction temperature, and is maintained with increasing initial pollutant concentration. Kinetic analyses elucidated that lindane degradation followed a first order reaction for both pollutant and ZVIM concentration. The kinetic model can also accurately predict the results in continuous mode (more realistic conditions), where the high stability of ZVIM has been thoroughly demonstrated. Further studies indicated that coexistence of common ions can (i) not affect (SO42–, Na+, Ca2+, Mg+) or (ii) promote (HCO3–, Cl–) the lindane dechlorination process. The results implied that the use of ZVIM is a potential approach for in situ remediation of soil and groundwater lindane contamination.Item Kinetics of Lindane Dechlorination by Zerovalent Iron Microparticles: Effect of Different Salts and Stability Study(Industrial & Engineering Chemistry Research, 2016) Domínguez Torre, Carmen María; Parchão, Joana; Rodríguez Vega, Sergio; Lorenzo Fernández, David; Romero Salvador, Arturo; Santos López, AuroraThis report is focused on the dechlorination of lindane, a recalcitrant and refractory pollutant, by zerovalent iron microparticles (ZVIM) in batch and continuous mode. Experimental variables such as initial lindane concentration, ZVIM dosage, and temperature were studied. Batch experiments indicate that the lindane dechlorination is enhanced with the increase of ZVIM dosage and reaction temperature, and is maintained with increasing initial pollutant concentration. Kinetic analyses elucidated that lindane degradation followed a first order reaction for both pollutant and ZVIM concentration. The kinetic model can also accurately predict the results in continuous mode (more realistic conditions), where the high stability of ZVIM has been thoroughly demonstrated. Further studies indicated that coexistence of common ions can (i) not affect (SO4 2−, Na+ , Ca2+, Mg+ ) or (ii) promote (HCO3 −, Cl−) the lindane dechlorination process. The results implied that the use of ZVIM is a potential approach for in situ remediation of soil and groundwater lindane contaminationItem 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; Fernández, Jesús ; Rodríguez Vega, Sergio; Domínguez Torre, Carmen María; Lominchar, Miguel Ángel; 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.