39 research outputs found
Hydrothermal Synthesis of rGO-TiO2 Composites as High-Performance UV Photocatalysts for Ethylparaben Degradation
This work was supported by the Spanish Ministry of Economy, Industry and competitiveness
and by FEDER (Project CTQ2016-80978-C2−1-R). M.R.-M. thanks to the Asociación Universitaria Iberoamericana de
Postgrado (AUIP) and the University of Jaen for the grant awarded and the financial support.A series of reduced graphene oxide-TiO2 composites (rGO-TiO2) were prepared by hydrothermal
treatment using graphite and titanium isopropoxide as raw materials. The structural, surface,
electronic, and optical properties of the prepared composites were extensively characterized by
N2 adsorption, FTIR, XRD, XPS, Raman spectroscopy, and DRS. GO was found to be effectively
reduced and TiO2 to be in pure anatase phase in all composites obtained. Finally, experiments were
performed to evaluate the effectiveness of these new materials as photocatalysts in the degradation
of ethylparaben (EtP) by UV radiation. According to the band-gap energies obtained (ranging
between 3.09 eV for 4% rGO-TiO2 to 2.55 eV for 30% rGO-TiO2), the rGO-TiO2 composites behave
as semiconductor materials. The photocatalytic activity is highest with a rGO content of 7 wt %
(7% rGO-TiO2), being higher than observed for pure TiO2 (Eg = 3.20 eV) and achieving 98.6% EtP
degradation after only 40 min of treatment. However, the degradation yield decreases with higher
percentages of rGO. Comparison with rGO-P25 composites showed that a better photocatalytic
performance in EtP degradation is obtained with synthesized TiO2 (rGO-TiO2), probably due to the
presence of the rutile phase (14.1 wt %) in commercial P25.Spanish Ministry of Economy, Industry and Competitiveness
CTQ2016-80978-C2 1-REuropean Union (EU)
CTQ2016-80978-C2 1-RAsociacion Universitaria Iberoamericana de Postgrado (AUIP)University of Jae
Solar Degradation of Sulfamethazine Using rGO/Bi Composite Photocatalysts
This work was supported by the Spanish Ministry of Economy, Industry and Competitiveness
and by FEDER (CTQ2016-80978-C2−1-R), and the authors thank to Dr. Isabel Guerra Tschuschke for the technical
advice during the VP-SEM study at the CIC-UGR.Heterogeneous photocatalysts for water decontamination were obtained by the optimized
synthesis of bismuth-functionalized reduced graphene oxide (rGO/Bi) using the Hummer method
and microwave treatment. Sulfamethazine (SMZ) was used as model pollutant to evaluate the
photocatalytic efficacy. Photocatalysts were characterized by VP-SEM, HRTEM, XDR, XPS, RAMAN,
and FTIR analyses, which confirmed the effective reduction of GO to rGO and the presence of bismuth
as a crystalline phase of Bi2O3 polydispersed on the surface. Their performance was influenced by the
rGO/Bi ratio, microwave temperature, and treatment time. The as-obtained 5%rGO/Bi composite had
the highest photocatalytic activity for SMZ degradation under visible light irradiation (λ > 400 nm),
achieving 100% degradation after only 2 h of treatment. The degradation yield decreased with
higher percentages of rGO. Accordingly, the rGO/Bi catalysts efficiently removed SMZ, showing
a high photocatalytic activity, and remained unchanged after three treatment cycles; furthermore,
cytotoxicity tests demonstrated the nontoxicity of the aqueous medium after SMZ degradation.
These findings support the potential value of these novel composites as photocatalysts to selectively
remove pollutants in water treatment plants.Spanish Ministry of Economy, Industry and Competitiveness
CTQ2016-80978-C2-1-REuropean Union (EU)
CTQ2016-80978-C2-1-
Comparative Study of the Oxidative Degradation of Different 4-Aminobenzene Sulfonamides in Aqueous Solution by Sulfite Activation in the Presence of Fe(0), Fe(II), Fe(III) or Fe(VI)
This study is focused on advanced oxidation technologies (AOTs) using the combined
effect of Fe(0–VI)/sulfite systems, that produce mainly SO4 radicals, to remove di erent
4-aminobenzene sulfonamides (SAs), namely sulfamethazine, sulfadiazine, sulfamethizole, from
aqueous solutions. Results obtained showed that neither sulfite nor iron alone is able to degrade
SAs; however, the combined effect depends on the oxidation state of iron species whose effectiveness
to activate sulfite to promote the degradation of SAs increased following this order: Fe(III) < Fe(II)
< Fe(0) < Fe(VI). Using Fe(VI)/sulfite, the complete removal of SAs was obtained in 5 min largely
surpassing the effectiveness of the other three systems. The sulfonamides’ removal percentage was
markedly influenced by sulfite concentration and dissolved oxygen, which improved the generation
of oxidant radicals. Response surface methodology was applied, and a quadratic polynomial model
was obtained, which allowed us to determine the percentage of SAs degradation as a function of
both the iron species and sulfite concentrations. The study of the influence of the water matrix on
these AOTs revealed an inhibition of SAs’ removal percentage when using ground water. This is
probably due to the presence of different anions, such as HCO3
-, Cl-, and SO4
2- in relatively high
concentrations. According to the byproducts identified, the proposed degradation pathways include
hydroxylation, SO2 extrusion, and different bond-cleavage processes. Cytotoxicity of degradation
byproducts, using MTS assay with HEK 293 and J774 cell lines for the first time, did not show an
inhibition in cell proliferation, sustaining the safety of the process.This research was funded by both Ministry of Science and Innovation of Spain, grant number
CTQ2016-80978-C2-1-R, and CONACyT (Mexico), grant number 407494
Characteristics and Behavior of Di erent Catalysts Used for Water Decontamination in Photooxidation and Ozonation Processes
The objective of this study was to summarize the results obtained in a wide research
project carried out for more than 15 years on the catalytic activity of di erent catalysts (activated
carbon, metal–carbon xerogels/aerogels, iron-doped silica xerogels, ruthenium metal complexes,
reduced graphene oxide-metal oxide composites, and zeolites) in the photooxidation (by using UV
or solar radiation) and ozonation of water pollutants, including herbicides, naphthalenesulfonic
acids, sodium para-chlorobenzoate, nitroimidazoles, tetracyclines, parabens, sulfamethazine,
sodium diatrizoate, cytarabine, and surfactants. All catalysts were synthesized and then texturally,
chemically, and electronically characterized using numerous experimental techniques, including
N2 and CO2 adsorption, mercury porosimetry, thermogravimetric analysis, X-ray di raction,
Fourier-transform infrared spectroscopy, Raman spectroscopy, X-ray photoelectron spectroscopy,
di use reflectance UV–vis spectroscopy, photoluminescence analysis, and transmission electron
microscopy. The behavior of these materials as photocatalysts and ozonation catalysts was related
to their characteristics, and the catalytic mechanisms in these advanced oxidation processes were
explored. Investigations were conducted into the e ects on pollutant degradation, total organic
carbon reduction, and water toxicity of operational variables and the presence of di erent chemical
species in ultrapure, surface, ground, and wastewaters. Finally, a review is provided of the most
recent and relevant published studies on photocatalysis and catalyzed ozonation in water treatments
using similar catalysts to those examined in our project.Spanish Ministry of Economy, Industry and Competitiveness
CTQ2016-80978-C2-1-REuropean Union (EU)
CTQ2016-80978-C2-1-RJunta de Andalucía
P18-RT-419
Life Cycle Assessment of Cement Production with Marble Waste Sludges
The construction industry has a considerable environmental impact in societies, which
must be controlled to achieve adequate sustainability levels. In particular, cement production contributes 5–8% of CO2 emissions worldwide, mainly from the utilization of clinker. This study applied Life Cycle Assessment (LCA) methodology to investigate the environmental impact of cement
production and explore environmental improvements obtained by adding marble waste sludges in
the manufacture of Portland cement. It was considered that 6–35% of the limestone required for its
production could be supplied by marble waste sludge (mainly calcite), meeting the EN 197-1:2011
norm. Energy consumption and greenhouse gas (GHG) emission data were obtained from the Ecovent database using commercial LCA software. All life cycle impact assessment indicators were
lower for the proposed “eco-cement” than for conventional cement, attributable to changes in the
utilization of limestone and clinker. The most favorable results were achieved when marble waste
sludge completely replaced limestone and was added to clinker at 35%. In comparison to conventional Portland cement production, this process reduced GHG emissions by 34%, the use of turbine
waters by 60%, and the emission of particles into the atmosphere by 50%. Application of LCA methodology allowed evaluation of the environmental impact and improvements obtained with the production of a type of functional eco-cement. This approach is indispensable for evaluating the environmental benefits of using marble waste sludges in the production of cement.Junta de Andalucía and Fondo Europeo de Desarrollo Regional (FEDER) Ref. P18-RT-419
Biosorption mechanism of Methylene Blue from aqueous solution onto White Pine (Pinus durangensis) sawdust: Effect of operating conditions
In this work, the biosorption mechanism of the cationic dye Methylene Blue (MB) on natural White Pine
sawdust (NS) (Pinus durangensis) was investigated. Likewise, the surface charge distribution of NS was
determined, and its point of zero charge was found to be 4.3. Besides, the capacity of the NS for adsorbing
MB was increased 1.7, 2.0 and 4.6 times when the pH was raised from 3 to 4.25, 3 to 7 and 3 to 10,
respectively. This behavior was attributed to the electrostatic attraction between the negatively charged
surface of NS and the cationic species MBþ. The adsorption capacity increased with increased temperature
because the adsorption was an endothermic process. The adsorption capacity was drastically
reduced by increasing the ionic strength of the solution corroborating with the fact that the electrostatic
attractions played a crucial role in the adsorption of MB on NS. It was also shown that the MB was
chemisorbed because the adsorption was not reversible. The predominant adsorption mechanisms were
the electrostatic attraction and chemisorption and not ion exchange.This work was funded by the Consejo Nacional de Ciencia y
Tecnologia, CONACyT, Mexico, through grants: CONAFOR-2010-
C02-148302 and CB-2012-02-182779
Participación del carbón activado en procesos de eliminación de fármacos presentes en las aguas
págs.: 273-324Capítulo incluido en el libro: Desarrollo y aplicaciones de materiales avanzados de carbón. Miguel Ángel Álvarez Merino, Francisco Carrasco Marín, Francisco José Maldonado Hódar (Editores). Sevilla: Univeridad Internacional de Andalucía, 2014. ISBN: 978-84-7993-247-3. Enlace: http://hdl.handle.net/10334
Influence of operational parameters on photocatalytic amitrole degradation using nickel organic xerogel under UV irradiation
The objectives of this study were to analyze the influence of different operational variables and to determine the time course of total organic carbon (TOC) and medium toxicity during amitrole (AMT) photodegradation in the presence of Ni xerogel (X-Ni) as photocatalyst. A further study objective was to analyze the influence of the type of water on the photodegradation process. Results show that the degradation rate is directly proportional to the initial X-Ni concentration up to a maximum of 250 mg/L with a slight decrease thereafter, indicating progressive photon absorption saturation of the catalyst for a given incident radiation flow. At concentrations close to 250 mg/L X-Ni, the AMT photodegradation rate is not affected by further increases in X-Ni concentration. In addition, AMT photolysis is highly pH-dependent and is generally favored at pH values at which AMT is in its ionic form. The increase observed in AMT degradation rate under alkaline conditions can be attributed to the higher generation of radicals. The presence of chloride reduces the AMT degradation rate, because Cl− anions behave as h+ and radical scavengers. The degradation rate is also decreased by addition to the medium of organic matter, which acts as a filter. The behavior of TOC removal kinetics during AMT degradation in the presence of X-Ni is similar to that observed for AMT degradation kinetics. Finally, we highlight that photocatalysis is more effective in ultrapure water than in wastewater or tap water. In all systems, the optimal catalyst concentration is 250 mg/L. The medium toxicity increases with longer treatment time, indicating the formation of by-products that are smaller than AMT and can more readily penetrate the cell.Financial support provided by
the Ministerio de Ciencia e Innovación (Spain) and FEDER
(Projects CTQ-2011-29035-C02-01 and CTQ-2011-29035-
C02-02), and by the University of Jaén (Project UJA
2015/06/01)
Vulnerable marine ecosystems and biological features of Gazul mud volcano (Gulf of Cádiz): A contribution towards a potential "Gulf of Cádiz" EBSA
The Gulf of Cádiz (GoC) represents an area of socioeconomic and scientific importance for oceanographic, geological and biological processes. An interesting feature of the GoC is the presence of a large amount of mud volcanoes (MVs) and diapirs that display different seepage, seabed types, oceanographic settings and biological communities. Detailed exploration of some MVs is still needed for detecting Vulnerable Marine ecosystems (VMEs) that seem to be rare in other areas of the GoC, improving the current knowledge on its biodiversity and ecological attributes. During different expeditions (MEDWAVES-ATLAS, INDEMARES-CHICA 0610 & 0412 and ISUNEPCA 0616) carried out in different years, biological samples and videos were obtained in Gazul MV (Spanish Margin of the GoC). The study of those samples and videos has revealed the presence of several ecologically important VMEs (e.g. 3 species of reef framework-forming corals, coral gardens including solitary scleractinians, gorgonians and antipatharians, as well as deep-sea sponge aggregations and chemosynthesis-related structures) and a large number of species occurring in this MV, including new records for the European margin, threatened species and non-previously described species. The combination of different environmental and anthropogenic factors allowed the present-day persistence of these VMEs in the GoC. Some of Gazul MV biological and ecological attributes fit several criteria of the Convention on Biological Diversity for EBSA description (e.g. 1,3,4,6) that, together with those of other areas of the GoC, may contribute to the future potential nomination of an EBSA in this area of the NE Atlantic
Estudio de la superficie de algunos haluros metálicos con estructura laminar
Tesis Univ. Granada. Facultad de Ciencias . Leída el 15 de marzo de 198