Person: Santos López, Aurora
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First Name
Aurora
Last Name
Santos López
Affiliation
Universidad Complutense de Madrid
Faculty / Institute
Ciencias Químicas
Department
Ingeniería Química y de Materiales
Area
Ingeniería Química
Identifiers
50 results
Search Results
Now showing 1 - 10 of 50
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 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 Remediation of the Alluvial Aquifer of the Sardas Landfill (Sabiñánigo, Huesca) by Surfactant Application(Sustainability, 2022) Guadaño, Joaquín; Gómez, Jorge; Fernández, Jesús; Lorenzo Fernández, David; Dominguez Torre, Carmen M.; Cotillas Soriano, Salvador; García Cervilla, Raúl; Santos López, AuroraSardas Landfill at Sabiñánigo Huesca is polluted with Dense Non-Aqueous Liquid Phases (DNAPLs) composed of a complex mixture of chlorinated organic compounds (COCs). This DNAPL was produced as liquid waste from lindane production being dumped decades ago in the unlined landfills close to the lindane factory. This DNAPL migrated by gravity through the subsurface and accumulated in the contact between the alluvial and marls layers (about 15 m b.g.l.). Seven injections of an aqueous emulsion of a biodegradable non-ionic surfactant (E-Mulse 3®) were carried out at the most polluted areas of the Sardas alluvial. Injections were carried out between April and November 2021 using different surfactant concentrations (6.7, 20, 25 and 50 g/L), injection volumes (0.2 to 7 m3) and injection flow rates (0.08–0.85 m3/h). Injected fluids were extracted in the same well or surrounding wells, and the time elapsed between surfactant injection and extraction varied between 24 and 72 h. A total of 22 m3 were injected into the alluvial, and more than double this injected volume was extracted. Injection and extraction points were in the contact between the marls and the alluvial layer. Extracted fluid accumulated in tanks, and phases separated. DNAPL recovered here was mobilized rather than solubilized and managed as toxic waste. The aqueous supernatant was treated in a wastewater treatment plant with physicochemical treatment (including adsorption in activated carbon) before being discharged into the environment. The transport of the injected fluids was monitored by conductivity profiles using bromide (260–538 mg·L−1) as a conservative tracer. High radial dispersion of the injected fluid was found. Surfactant losses by adsorption in the alluvial and absorption in DNAPL were noticed, and both surfactant and contamination did not escape from the capture zone. Monitoring since 2018 of the COCS in groundwater and the DNAPL presence in the contact between alluvial and marls layers showed a significant reduction of COCs in the treated zone with the surfactant injections.- Project number: 332
Item Autoaprendizaje a través de problemas abiertos(2021) Santos López, Aurora; Dominguez Torre, Carmen María; García-Cervilla, Raúl; Checa-Fernández, Cristina AliciaEl principal objetivo del presente proyecto de innovación es desarrollar la autonomía y razonamiento crítico del estudiante a través de problemas que él mismo propondrá (a partir de una búsqueda bibliográfica) y resolverá. Además, se pedirá a los alumnos que planteen soluciones abiertas a los problemas, fomentando su pensamiento crítico y haciendo que se proyecten en situaciones reales. Item Regeneration of Granulated Spent Activated Carbon with 1,2,4-Trichlorobenzene Using Thermally Activated Persulfate(Industrial & Engineering Chemistry Research, 2022) Sánchez Yepes, Andrés; Santos López, Aurora; Rosas, Juana M.; Rodríguez Mirasol, José; Cordero, Tomás; Lorenzo Fernández, DavidChlorinated organic compounds (COCs) are persistent organic pollutants often found in groundwater near industrial sites or in industrial wastewaters. Adsorption into activated carbon is a common strategy to remediate these waters, but spent activated carbon results in a toxic residue to manage. To avoid the transport of the chlorinated compounds out of the site, the in-situ regeneration of the spent activated carbon can be considered for reuse to implement a circular economy. In this work, the regeneration of a commercial granular activated carbon (GAC) has been carried out using thermally activated sodium persulfate (TAP). GAC was previously saturated in 1,2,4-trichlorobenzene (124-TCB) as the model compound. The initial adsorption value was 350 mg124 TCB·gGAC −1 . First, the nonproductive consumption of sodium persulfate was studied at different temperatures using nonsaturated GAC. Then, the regeneration of the saturated GAC (5 g) was studied by an aqueous solution (166 mM) of TAP (1 L) at a temperature range from 20 to 80 °C. The possible recovery of the adsorption capacity was studied after 3 h of treatment in three successive adsorption−regeneration cycles at the selected temperature (60 °C). The physicochemical changes of the GAC were also investigated before and after the regeneration treatments. The results evidence the significant deposition of sulfate on the GAC after each treatment of regeneration, which avoids the recovery of the initial adsorption capacity. Therefore, each regeneration cycle was necessarily followed by a washing step at 60 °C to remove this sulfate. After that, the regeneration treatment achieved a stable and high recovery of the initial adsorption capacity of about 48.2%.Item LED visible light assisted photochemical oxidation of HCHs in aqueous phases polluted with DNAPL(Process Safety and Environmental Protection, 2022) Conte, Leandro O.; Cotillas Soriano, Salvador; Sánchez Yepes, Andrés; Lorenzo Fernández, David; Santos López, AuroraThis work focuses on removing hexachlorocyclohexanes (HCHs) found in groundwater polluted with dense non-aqueous phase liquids (DNAPLs) by photo-oxidation with hydrogen peroxide or persulfate using LED visible light and ferrioxalate as the catalyst. Single oxidation tests were also performed to evaluate the contribution of LED-vis light on HCHs removal. Results show that it is possible to attain the degradation of HCHs up to 85% in 420 min with persulfate, whereas percentages lower than 40% are obtained when using hydrogen peroxide. Using both oxidants in the presence of ferrioxalate and LED visible light promotes the generation of hydroxyl and sulfate radicals under circumneutral pH values, which are the main responsible species for HCHs removal. Specifically, an oxidant conversion higher than 50% was achieved during the photochemical treatment with both oxidants, whereas conversions below 20% were obtained in the absence of LED visible light irradiation. On the other hand, DNAPL produced as liquid residuum of lindane production contains other chlorinated organic compounds (COCs), which are susceptible to being oxidized by hydroxyl and sulfate radicals, generating competitive oxidation reactions. The final conversion of chlorbenzenes reaches values close to 100% and HCHs are only effectively removed when persulfate is used as the oxidant. This better performance indicates that the photo-oxidation of DNAPL polluted groundwater with LED-vis light should be carried out with persulfate to ensure the removal of more dangerous COCs. This confirms the excellent ability of sulfate radicals for C-Cl bond breakdown.Item Sustainable reuse of toxic spent granular activated carbon by heterogeneous fenton reaction intensified by temperature changes(Chemosphere, 2023) Sánchez Yepes, Andrés; Santos López, Aurora; Rosas, Juana M.; Rodríguez-Mirasol, José; Cordero, Tomás; Lorenzo Fernández, DavidA common strategy for removing highly toxic organic compounds, such as chlorinated organic compounds, is their adsorption on granular activated carbon. Spent granular activated carbon results in a toxic residue to manage; therefore, the regeneration and reuse of granular activated carbon on the site would be advisable. This work studies the regeneration of a granular activated carbon saturated in 1,2,4-trichlorobenzene, chosen as the model chlorinated organic compounds, by heterogeneous Fenton, where iron was previously immobilised on the granular activated carbon surface. This methodology avoids the addition of iron to the aqueous phase at concentrations above the allowable limits and the need for acidification. Three successive cycles of adsorption-regeneration were carried out batchwise (5 gGAC·L−1) with a granular activated carbon saturated with 300 mg124-TCB·gGAC−1. The recovery of the adsorption capacity after regeneration was studied with H2O2 (166 mM, 1.5 the stoichiometric dosage), at different concentrations adsorbed with iron adsorbed concentrations (0–12 mgFe·gGAC−1) and temperatures (20–80 °C). Stable recovery of the adsorption capacity values of 65% were obtained at 180 min with 12 mgFe·gGAC−1 and 60 °C. The porosity and surface chemistry of the adsorbent remained very similar after different adsorption-regeneration cycles without iron leaching into the aqueous phase. The oxidant consumption was close to the stoichiometric value for the mineralization of 1,2,4−trichlorobenzene, with a low unproductive consumption of H2O2 with granular activated carbon. In addition, no aromatic or chlorinated by-products were detected in the aqueous solution obtained in the regeneration process. The negligible toxicity of the aqueous phase with the Microtox bioassay confirmed the absence of toxic oxidation by-products. Keywords: Heterogeneous fenton; Adsorption; Regeneration; Activated carbon; Chlorinated organic compounds- Project number: PIMCD328/23-24
Item Elaboración de una metodología basada en el aprendizaje autónomo de herramientas informáticas para fomentar las competencias digitales de los estudiantes de Ingeniería Química(2024) Lorenzo Fernández, David; Checa Fernández, Cristina Alicia; Cotillas Soriano, Salvador; Domínguez Torre, Carmen María; Herraíz Carboné, Miguel; García Cervilla, Raúl; Martínez Rodríguez, Mercedes; Rodríguez Vega, Sergio; Sánchez Yepes, Andrés; Santos López, Aurora Item Remediation of real soils polluted with pesticides by activated persulfate and surfactant addition(Journal of Water Process Engineering, 2023) Checa Fernández, Cristina Alicia; Santos López, Aurora; Romero Salvador, Arturo; Domínguez Torre, Carmen MaríaThe existence of soils contaminated with organochlorine pesticides represents a serious environmental problem. In this work, a real soil contaminated with hexachlorocyclohexanes (ΣHCH = 373 mg kg−1), persistent organic pollutants included in the Stockholm Convention, was remediated. Surfactants were used to enhance the pollutants solubilization and activated persulfate (PS) oxidation to degrade the pollutants. Solubilization experiments were performed to evaluate the effect of surfactant (sodium dodecyl sulfate (SDS), Emulse-3® (E3) and Tween-80® (T80)), pH, reagents addition order and concentration (Csurfactant = 0–10 g L−1, CNaOH = 0–13.5 g L−1). Surfactants selection was performed attending to their ability to solubilize chlorinated organic compounds (COCs). The use of surfactants improved COCs solubilization, especially at pH > 12; conditions at which HCHs hydrolyze to trichlorobenzenes (TCBs), with higher solubility. The higher the surfactant concentration, the higher the COCs concentration in the emulsion. COCs solubilization of 83 % and 89 % were achieved in three surfactant consecutive cycles at highly alkaline conditions using SDS and E3, respectively (T80 was unstable). The resulting emulsions were treated by PS activated by alkali and intensified by temperature. COCs conversion of 30 % and 96 % were achieved when treating E3 and SDS-emulsions (72 h), respectively, highlighting the suitability of SDS for the integrated process.Item Application of Chelating Agents to Enhance Fenton Process in Soil Remediation: A Review(Catalysts, 2021) Checa-Fernández, Cristina Alicia; Santos López, Aurora; Romero, Arturo; Dominguez Torre, Carmen M.Persistent organic contaminants affecting soil and groundwater pose a significant threat to ecosystems and human health. Fenton oxidation is an efficient treatment for removing these pollutants in the aqueous phase at acidic pH. However, the in-situ application of this technology for soil remediation (where pHs around neutrality are required) presents important limitations, such as catalyst (iron) availability and oxidant (H2O2) stability. The addition of chelating agents (CAs), forming complexes with Fe and enabling Fenton reactions under these conditions, so-called chelate-modified Fenton process (MF), tries to overcome the challenges identified in conventional Fenton. Despite the growing interest in this technology, there is not yet a critical review compiling the information needed for its real application. The advantages and drawbacks of MF must be clarified, and the recent achievements should be shared with the scientific community. This review provides a general overview of the application of CAs to enhance the Fenton process for the remediation of soils polluted with the most common organic contaminants, especially for a deep understanding of the activation mechanisms and influential factors. The existing shortcomings and research needs have been highlighted. Finally, future research perspectives on the use of CAs in MF and recommendations have been provided.