Person: García Cervilla, Raúl
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First Name
Raúl
Last Name
García Cervilla
Affiliation
Universidad Complutense de Madrid
Faculty / Institute
Ciencias Químicas
Department
Ingeniería Química y de Materiales
Area
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4 results
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Item Abatement of chlorobenzenes in aqueous phase by persulfate activated by alkali enhanced by surfactant addition(Journal of Environmental Management, 2022) García Cervilla, Raúl; Santos López, Aurora; Romero, Arturo; Lorenzo Fernández, DavidSites polluted by dense non-aqueous phases (DNAPLs) constitute an environmental concern. In situ chemical oxidation (ISCO) application is limited since oxidation often occurs in the aqueous phase and contaminants are usually hydrophobic. In this work, ISCO enhanced by the surfactant addition (S–ISCO) was studied for a complex liquid mixture of chlorinated organic compounds (COCs) using persulfate (PS) activated by alkali (PSA) as oxidant and Emulse-3® as a commercial non-ionic surfactant. The reaction between E3 and PSA was investigated in the absence and presence of solubilized COCs in the following concentration ranges: COCs 1.2–50 mM, PS 84–336 mM, NaOH:PS molar ratio of 2, and surfactant concentration 1–10 g⋅L− 1. In the experiments carried out in the absence of COCs, the unproductive consumption of PS was studied. The higher the surfactant concentration, the lower the ratio PS consumed to the initial surfactant concentration due to more complex micelle structures hindering the oxidation of surfactant molecules. This hindering effect was also noticed in the oxidation of solubilized COCs. The reduction of chlorobenzenes by PSA was negligible at surfactant concentrations above 2.5 g⋅L− 1, independently of the COCs concentration solubilized. Instead, a surfactant concentration of about 1 and PS concentration of 168 mM yielded a significant decrease in the time required to abate a mass of DNAPL, compared with an ISCO process, with a bearable increase in the unproductive consumption of PSItem Partition of a mixture of chlorinated organic compounds in real contaminated soils between soil and aqueous phase using surfactants: Influence of pH and surfactant type(Journal of Environmental Chemical Engineering, 2021) García Cervilla, Raúl; Santos López, Aurora; Romero, Arturo; Lorenzo Fernández, DavidThe equilibrium between surfactant adsorption and contaminants desorption was studied. Two soil samples from a polluted site with residues from lindane production, compounded of a complex mixture of 28 chlorinated organic compounds (COCs) and different concentration of COCs in soil (2.27 and 34.69 mmolCOCs⋅kg− 1 soil), were used. Soil was in contact with aqueous surfactant solutions (1–15 g⋅L− 1) of nonionic (E-Mulse® 3, and Tween® 80) and anionic (sodium dodecylsulfate) surfactants. Due to alkaline pH promoting the dehydrochlorination of COCs, neutral pH and strongly alkaline pH (pH > 12) were studied. It was found that the higher the COCs concentration adsorbed in soil, the higher the adsorption of the surfactants, finding an irreversible adsorption in the case of nonionic surfactants. The desorption of COCs increased with the surfactant concentration in the aqueous phase and was not selective towards any contaminant. Although at neutral pH, higher COC desorption was found with nonionic surfactants, at alkaline pH surfactant the anionic surfactant improved its COCs desorption capacity significantly. Finally, the adsorption of the surfactants was well adjusted to Langmuir, and the apparent partition coefficient predicted the partitioning of COCs between the soil and aqueous phases, which changes with the surfactant concentration in the aqueous solution.Item Simultaneous addition of surfactant and oxidant to remediate a polluted soil with chlorinated organic compounds: Slurry and column experiments(Journal of Environmental Chemical Engineering, 2022) García Cervilla, Raúl; Santos López, Aurora; Romero, Arturo; Lorenzo Fernández, DavidThe inadequate management of wastes associated with chlorinated organic compounds (COCs) has become a huge environmental problem. Surfactant Enhanced In-Situ Chemical Oxidation (S-ISCO) was studied as a successful technique to remediate polluted sites. This work investigated the reaction between an aqueous solution of nonionic surfactant (Emulse-3®) and an oxidant (sodium persulfate activated with NaOH) with a real polluted soil with a complex mixture of COCs from lindane liquid wastes. Two experimental setups were used. In the first one, the reactions were carried out in batch mode under slurry conditions using different surfactant concentrations (0–10 g⋅L− 1), 210 mM of persulfate and 420 mM of NaOH with an aqueous to soil ratio VL/W = 10 L⋅kg− 1. The runs were carried using a column loaded with the soil in the second experimental setup. The solution of surfactant, oxidant and activator was put in contact with soil in four pore volumes with a ratio aqueous to soil ratio VL/W = 0.2 L⋅kg− 1. Under these experimental conditions, the surfactant addition improved the reduction of COCs compared with the application carried out without surfactant, from 40.1% to values of conversion of 64.8 – 90.4%. However, an excess of surfactant hindered the COCs oxidation and increased the unproductive consumption of the oxidant, resulting in an optimal value of surfactant in the aqueous phase (1–2 g⋅L− 1). A remarkable drop in the surfactant concentration in the aqueous phase and COCs solubilized was noticed in column runs due to the surfactant adsorption.Item Surfactant-Enhanced Solubilization of Chlorinated Organic Compounds Contained in DNAPL from Lindane Waste: Effect of Surfactant Type and pH(International Journal of Environmental Research and Public Health, 2020) García Cervilla, Raúl; Romero, Arturo; Santos López, Aurora; Lorenzo Fernández, DavidApplication of surfactants in the remediation of polluted sites with dense nonaqueous phase liquid (DNAPL) still requires knowledge of partitioning between surfactants and pollutants in the organic and aqueous phases and the time necessary to reach this balance. Two real DNAPLs, generated as wastes in the lindane production and taken from the polluted sites from Sabiñanigo (Spain), were used for investigating the solubilization of 28 chlorinated organic compounds (COCs) applying aqueous surfactant solutions of three nonionic surfactants (E-Mulse® 3 (E3), Tween®80 (T80), and a mixture of Tween®80-Span®80 (TS80)) and an anionic surfactant (sodium dodecyl sulfate (SDS)). The initial concentrations of surfactants were tested within the range of 3–17 g·L −1 . The pH was also modified from 7 to >12. The uptake of nonionic surfactants into the organic phase was higher than the anionic surfactants. Solubilization of COCs with the nonionic surfactants showed similar molar solubilization ratios (MSR = 4.33 mmolCOCs·g −1 surf), higher than SDS (MSR = 0.70 mmolCOCs·g −1 SDS). Furthermore, under strong alkaline conditions, the MSR value of the nonionic surfactants was unchanged, and the MSR of SDS value increased (MSR = 1.32 mmolCOCs·g −1 SDS). The nonionic surfactants did not produce preferential solubilization of COCs; meanwhile, SDS preferentially dissolved the more polar compounds in DNAPL. The time required to reach phase equilibrium was between 24 and 48 h, and this contact time should be assured to optimize the effect of the surfactant injected on COC solubilization.