Browsing by Keyword "SDG 6 - Clean Water and Sanitation"
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Item Bacterial-cellulose-derived carbonaceous electrode materials for water desalination via capacitive method: The crucial role of defect sites: The crucial role of defect sites(2020-10-15) Belaustegui, Yolanda; Pantò, Fabiola; Urbina, Leire; Corcuera, Maria Angeles; Eceiza, Arantxa; Palella, Alessandra; Triolo, Claudia; Santangelo, Saveria; VALORIZACIÓN DE RESIDUOSElectrosorptive desalination is a very simple and appealing approach to satisfy the increasing demand for drinking water. The large-scale application of this technology calls for the development of easy-to-produce, cheap and highly performing electrode materials and for the identification and tailoring of their most influential properties, as well. Here, biosynthesised bacterial cellulose is used as a carbon precursor for the production of three-dimensional nanostructures endowed with hierarchically porous architecture and different density and type of intrinsic and hetero-atom induced lattice defects. The produced materials exhibit unprecedented desalination capacities for carbon-based electrodes. At an initial concentration of 585 mg L−1 (10 mmol L−1), they are able to remove from 55 to 79 mg g−1 of salt; as the initial concentration rises to 11.7 g L−1 (200 mmol L−1), their salt adsorption capacity reaches values ranging between 1.03 and 1.35 g g−1. The results of the thorough material characterisation by complementary techniques evidence that the relative amount of oxygenated surface functional species enhancing the electrode wettability play a crucial role at lower NaCl concentrations, whereas the availability of active non-sp2 defect sites for adsorption is mainly influential at higher salt concentrations.Item Cements based on kaolinite waste(2018-08-10) García Giménez, Rosario; Vigil de la Villa Mencía, Raquel; Frías, Moises; Martínez Ramírez, Sagrario; Vegas Ramiro, Iñigo; Fernández Carrasco, Lucía; GENERALThe cement industry involves high-energy consumption that generates high CO2 emissions into the atmosphere. Environmental concerns can be addressed by replacing parts of Portland cement clinkers with pozzolanic materials in mortars and concrete. Slag, fly ash and silica fume are materials considered for the planned replacement. Research studies on clay minerals, such as kaolinite, are being followed with special attention by the scientific community and the cement industry. It is well known that these minerals require an activation process to transform kaolinite (K) into metakaolinite (MK). MK is an amorphous material from the transformation of K with high pozzolanic activity, which is its capacity to react with the portlandite released during the hydration of Portland cement, generating compounds such as C–S–H gels and some aluminum-phase hydrates. One of the MK production methods is heat treatment controlled by kaolinite at temperatures in the range of 600–900°C. Different residues have been used (coal mining, paper sludge and waste from a drinking water treatment plant) activated at 600°C for 2h to elaborate blended cements. Due to their good behaviour as future eco-efficient additions, this research is a study by x-ray fluorescence (XRF), x-ray diffraction (XRD) and scanning electron microscopy (SEM) of their influence on the performances of blended cement mixtures (binary and ternary one), with substitutions of pozzolan ratio at 28 days of hydration. The porosity of pozzolanic cements decreases because of the formation of hydrated phases during pozzolanic reaction.Item Effect of water matrix on photocatalytic degradation and general kinetic modeling(2016-01-01) RIOJA, NEREA; ZORITA, SAIOA; PEÑAS, FRANCISCO JAVIER; ADAPTACIÓN AL CAMBIO CLIMÁTICOPhotocatalysis employing TiO2 nanoparticles was studied to assess the effect of aqueous matrix nature in the degradation of clofibric acid (CFA) under UV-A radiation. Aeroxide TiO2-P25 at 0.50 g/L was the most effective catalyst among those tested, with a CFA degradation of 98.5% after 15 min. The CFA photodegradation in environmental waters (tap, mineral, river and recycled wastewater) and in the presence of inorganic (NaCl, FeCl3, FeCl2, AlCl3, CaCl2, Al-2(SO4)(3), Fe-2(SO4)(3), Na2SO4, NaHCO3, and Na2CO3) and organic compounds (humic acids, and a surfactant) commonly found in real waters was compared to that obtained in pure water. In general, the removal efficiency decreased with inorganic salts, especially with sulfates and carbonates (>70% deactivation), and also in environmental waters (>90%). A general kinetic model has been developed to describe the CFA photo degradation depending on the type and concentration of substances present in water. The first-order kinetic constants were estimated by defining a characteristic parameter for each ion species tested in the aqueous matrix. High correlation (R-2 >0.99 in most cases) was observed between experimental CFA concentrations and those predicted by the model.Item Effects of in situ Remediation With Nanoscale Zero Valence Iron on the Physicochemical Conditions and Bacterial Communities of Groundwater Contaminated With Arsenic(2021-03-17) Castaño, Ana; Prosenkov, Alexander; Baragaño, Diego; Otaegui, Nerea; Sastre, Herminio; Rodríguez-Valdés, Eduardo; Gallego, José Luis R.; Peláez, Ana Isabel; Tecnalia Research & InnovationNanoscale Zero-Valent Iron (nZVI) is a cost-effective nanomaterial that is widely used to remove a broad range of metal(loid)s and organic contaminants from soil and groundwater. In some cases, this material alters the taxonomic and functional composition of the bacterial communities present in these matrices; however, there is no conclusive data that can be generalized to all scenarios. Here we studied the effect of nZVI application in situ on groundwater from the site of an abandoned fertilizer factory in Asturias, Spain, mainly polluted with arsenic (As). The geochemical characteristics of the water correspond to a microaerophilic and oligotrophic environment. Physico-chemical and microbiological (cultured and total bacterial diversity) parameters were monitored before and after nZVI application over six months. nZVI treatment led to a marked increase in Fe(II) concentration and a notable fall in the oxidation-reduction potential during the first month of treatment. A substantial decrease in the concentration of As during the first days of treatment was observed, although strong fluctuations were subsequently detected in most of the wells throughout the six-month experiment. The possible toxic effects of nZVI on groundwater bacteria could not be clearly determined from direct observation of those bacteria after staining with viability dyes. The number of cultured bacteria increased during the first two weeks of the treatment, although this was followed by a continuous decrease for the following two weeks, reaching levels moderately below the initial number at the end of sampling, and by changes in their taxonomic composition. Most bacteria were tolerant to high As(V) concentrations and showed the presence of diverse As resistance genes. A more complete study of the structure and diversity of the bacterial community in the groundwater using automated ribosomal intergenic spacer analysis (ARISA) and sequencing of the 16S rRNA amplicons by Illumina confirmed significant alterations in its composition, with a reduction in richness and diversity (the latter evidenced by Illumina data) after treatment with nZVI. The anaerobic conditions stimulated by treatment favored the development of sulfate-reducing bacteria, thereby opening up the possibility to achieve more efficient removal of As.Item Electro-spun graphene-enriched carbon fibres with high nitrogen-contents for electrochemical water desalination(2018-02-15) Belaustegui, Yolanda; Zorita, Saioa; Fernández-Carretero, Francisco; García-Luis, Alberto; Pantò, Fabiola; Stelitano, Sara; Frontera, Patrizia; Antonucci, Pierluigi; Santangelo, Saveria; Tecnalia Research & Innovation; VALORIZACIÓN DE RESIDUOS; ADAPTACIÓN AL CAMBIO CLIMÁTICO; TECNOLOGÍAS DE HIDRÓGENOElectro-spun carbon fibres doped with very high nitrogen concentrations (19–21 wt%) are obtained operating carbonisation at low temperature (500 °C). The as-synthesised fibres are evaluated as electrode materials for the electrochemical desalination of water. The effect of the enrichment of the nitrogen doped carbon fibres with thermally reduced graphene oxide is also investigated. The fibrous electrodes are able to remove amazing amounts of NaCl (17.0–27.6 mg/g) from a salty solution with an initial concentration of 585 mg/L. The nitrogen doping, which dramatically improves the wettability, plays a crucial role in determining the outstanding electro-sorption capacities of the fibres. It allows fully profiting of the more favourable pore size distribution in the graphene-enriched fibres, endowed with higher conductivity and capacitance, for the obtainment of unprecedented electro-sorption capacities via an extremely simple synthesis process, with no need of activation treatments.Item Field-scale demonstration of in situ immobilization of heavy metals by injecting iron oxide nanoparticle adsorption barriers in groundwater(2021-02) Mohammadian, Sadjad; Krok, Beate; Fritzsche, Andreas; Bianco, Carlo; Tosco, Tiziana; Cagigal, Ekain; Mata, Bruno; Gonzalez, Veronica; Diez-Ortiz, Maria; Ramos, Vanesa; Montalvo, Daniela; Smolders, Erik; Sethi, Rajandrea; Meckenstock, Rainer U.; TRAZABILIDAD CIRCULARRemediation of heavy metal-contaminated aquifers is a challenging process because they cannot be degraded by microorganisms. Together with the usually limited effectiveness of technologies applied today for treatment of heavy metal contaminated groundwater, this creates a need for new remediation technologies. We therefore developed a new treatment, in which permeable adsorption barriers are established in situ in aquifers by the injection of colloidal iron oxides. These adsorption barriers aim at the immobilization of heavy metals in aquifers groundwater, which was assessed in a large-scale field study in a brownfield site. Colloidal iron oxide (goethite) nanoparticles were used to install an in situ adsorption barrier in a very heterogeneous, contaminated aquifer of a brownfield in Asturias, Spain. The groundwater contained high concentrations of heavy metals with up to 25 mg/L zinc, 1.3 mg/L lead, 40 mg/L copper, 0.1 mg/L nickel and other minor heavy metal pollutants below 1 mg/L. High amounts of zinc (>900 mg/kg), lead (>2000 mg/kg), nickel (>190 mg/kg) were also present in the sediment. Ca. 1500 kg of goethite nanoparticles of 461 ± 266 nm diameter were injected at low pressure (< 0.6 bar) into the aquifer through nine screened injection wells. For each injection well, a radius of influence of at least 2.5 m was achieved within 8 h, creating an in situ barrier of 22 × 3 × 9 m. Despite the extremely high heavy metal contamination and the strong heterogeneity of the aquifer, successful immobilization of contaminants was observed in the tested area. The contaminant concentrations were strongly reduced immediately after the injection and the abatement of the heavy metals continued for a total post-injection monitoring period of 189 days. The iron oxide particles were found to adsorb heavy metals even at pH-values between 4 and 6, where low adsorption would have been expected. The study demonstrated the applicability of iron oxide nanoparticles for installing adsorption barriers for containment of heavy metals in contaminated groundwater under real conditions.Item High-Performance Carbon Electrodes Modified with Polyaniline for Stable and Selective Anion Separation(2022-06-01) Zornitta, Rafael L.; Ruotolo, Luis A.M.; de Smet, Louis C.P.M.; Tecnalia Research & InnovationCapacitive deionization (CDI) is a technology used for water desalination and ion recovery based on the use of capacitive electrodes. Typically, the porous carbon electrodes used for CDI display limited ion storage capacity and selectivity due to the mechanism of ion storage in the electric double layer, but impressive improvements have been achieved using alternative, redox-based electrode materials, including conducting polymers like polyaniline (PAni). PAni is capable of capturing anions based on redox chemistry, but it degrades at anodic potentials typically used in CDI. In this work, we employed a multi-channel membrane CDI cell to map the stability window of a porous carbon electrode modified with PAni by controlling the anodic potential. We demonstrated for the first time that applying a potential as low as + 0.35 V (vs. Ag/AgCl) yields a stable and high chloride removal capacity (65 mgCl/gAnode) with charge and coulombic efficiencies close to 100% for CDI. Furthermore, this is first work to explore the selectivity of the PAni-modified CDI electrodes towards chloride in binary solutions, evidencing that chloride is preferred regardless the valence of the competing anions. We believe that this work provides an important contribution for a larger figure, one in which CDI can be used for both high-performance water desalination, and efficient anion-selective removal and recovery.Item Removal of TiO 2 nanoparticles from water by low pressure pilot plant filtration(2018-03-15) Olabarrieta, Josune; Monzón, Oihane; Belaustegui, Yolanda; Alvarez, Jon-Iñaki; Zorita, Saioa; VALORIZACIÓN DE RESIDUOS; ADAPTACIÓN AL CAMBIO CLIMÁTICORising use of nanoparticles in manufacturing as well as in commercial products bring issues related to environmental release and human exposure. A large amount of TiO2 nanoparticles will eventually reach wastewater treatment plants. Low pressure membrane filtration has been suggested as a feasible treatment of water streams. This study investigated first at laboratory scale the influence of: i) membrane material, ii) pore size and iii) water chemistry on nTiO2 removal. TiO2 retention was governed by the cake layer formation mechanism and significant retention of nanoparticles was observed even for filters having considerably larger pores than nTiO2. PVDF showed a great potential for nTiO2 rejection. Additionally, filtration pilot plant experiments were carried out using PVDF membranes (0.03 and 0.4 μm pore size). The release of nTiO2 in the pilot scale filtration system was always above the instrumental detection limit (> 1.5 μg/L) and in most cases below 100 μg/L regardless of the pore size and applied conditions. The nTiO2 membrane breakthrough predominantly occurred in the first few minutes after backwashes and ceased when the cake layer was formed. Ultrafiltration and microfiltration were comparable with rejection of nTiO2 above 95% at similar permeate flow rates. Nevertheless, ultrafiltration is more promising than microfiltration because it allowed longer operation times between backwash cycles.Item Three-dimensional reduced graphene oxide decorated with iron oxide nanoparticles as efficient active material for high performance capacitive deionization electrodes(2021-05-15) Belaustegui, Yolanda; Rincón, Inés; Fernández-Carretero, Francisco; Azpiroz, Patxi; García-Luís, Alberto; Tanaka, David Alfredo Pacheco; Tecnalia Research & Innovation; VALORIZACIÓN DE RESIDUOS; TECNOLOGÍAS DE HIDRÓGENO; TECNOLOGÍA DE MEMBRANAS E INTENSIFICACIÓN DE PROCESOSA three-dimensional reduced graphene oxide decorated with iron oxide nanoparticles (3D rGO-Fe2O3) material with a suitable porous structure was synthesised using a one-step hydrothermal process in order to fabricate novel electrodes for capacitive deionization (CDI) water desalination. The morphological and structural properties of the as-synthesised compounds were characterised by scanning electron microscopy (SEM), Brunauer-Emmett-Teller (BET), Raman spectroscopy (RS), X-ray diffraction (XRD) and thermal gravimetric analysis (TGA). The CDI electrodes were electrochemically analysed by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). A maximum value of specific capacitance of 345 F g−1 was achieved at 5 mV s−1 scan rate using a NaCl 0.1 mol L−1 solution. The ion removal performance of the CDI electrodes was evaluated with NaCl solutions of different concentrations, showing electrosorption capacities as high as 945 mg g−1 for 11,700 mg L−1 (200 mmol L−1) NaCl solutions, which substantially surpasses results of other carbon-based CDI electrodes.Item TiO2-Doped Electrospun Nanofibrous Membrane for Photocatalytic Water Treatment(2019-04-26) Blanco, Miren; Monteserín, Cristina; Angulo, Adrián; Pérez-Márquez, Ana; Maudes, Jon; Murillo, Nieves; Aranzabe, Estíbaliz; Ruiz-Rubio, Leire; Vilas, Jose Luis; Tecnalia Research & Innovation; PRINTEXThis work has been focused on the one-step fabrication by electrospinning of polyamide 6 (PA6) nanofibre membranes modified with titanium dioxide nanoparticles (TiO2), where these TiO2 nanoparticles aggregates could induce a photocatalytic activity. The main potential application of these membranes could be the purification of contaminated water. Thus, it is important to analyse the contaminant degradation capability since in these membranes this is based on their photocatalytic activity. In this work, the effect of the photocatalysis has been studied both on the degradation of an organic model contaminant and on the removal of Escherichia coli and other coliform bacteria. As a result, it was observed that these membranes present excellent photocatalytic activity when they are irradiated under UV light, allowing a 70% reduction of an organic model pollutant after 240 min. In addition, these membranes successfully removed Escherichia coli and other coliform bacteria in artificially inoculated water after 24 h of contact with them. Moreover, the stand-alone structure of the membranes allowed for the reusing of the immobilized catalyst. The experimental evidence indicated that developed nanofibre membranes are a fast and efficient solution for polluted water decontamination based on photocatalysis. Their use could contribute to guarantee a fresh water level and quality, mitigating the water scarcity problem worldwide.