TECNALIA Publications Repository :: Browsing by Keyword "Environmental Chemistry"

Browsing by Keyword "Environmental Chemistry"

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Acute toxicity of nanosized TiO2 to Daphnia magna under UVA irradiation
(2012-11) Amiano, Irene; Olabarrieta, Josune; Vitorica, Joana; Zorita, Saioa; DF_Bioeficacia; ADAPTACIÓN AL CAMBIO CLIMÁTICO
The production and use of nanoparticles (NPs), especially those of titanium dioxide (TiO2) have increased steadily within the last decade. Common knowledge of photoactive nanosized TiO2 (nTiO2) effects on freshwater organisms is largely limited to acute toxicity tests without taking into consideration solar ultraviolet-A (UVA) irradiation. The authors' approach in the present study, based on a combination of a standardized ecotoxicology method (Organization for Economic Cooperation and Development [OECD] test 202) and the expected solar UVA contribution, will allow a more realistic understanding of the toxicity of TiO2 to Daphnia magna. The results show that the contribution of UVA to TiO2 toxicity cannot be ignored. The half-maximal effective concentration values (median effective concentration [EC50], immobilization as the endpoint) using Organization for Standardization (ISO) test water as well as river water decreased from 29.7 to 33.6mg/L under dark conditions to 1.2 to 3.4mg/L TiO2 after exposure to 0.56mW/cm2 UVA radiation. The authors also discuss possible mechanisms of NPs toxicity and the accuracy of results in terms of problems observed, such as solubilization and sedimentation of NPs, in ecotoxicological testing of nTiO2.
Alloying elements liquid addition to optimize secondary metallurgy
(2018-01-01) Jimbert, P.; Iturrondobeitia, M.; Fernandez-Martinez, R.; Barbero, J. I.; Serna, M.; Eguizabal, D.; Oncala, J. L.; Artola, A.; Iparraguirre, J. A.; Arteaga, A.; PROMETAL; SG; CIRMETAL
During the last years, numerous secondary metallurgical technologies have been developed. The present study presents a new technology based on adding all the alloying elements in liquid state. In this new process, a molten bath of the appropriate composition is made with alloying elements and deoxidants (in an induction furnace). This molten alloy is introduced into the liquid steel at the beginning of secondary metallurgy. With this new process, in addition to improving the mixing between alloy elements and steel, its final objective is to improve the process of secondary metallurgy in order to: reduce the time of secondary metallurgy, reduce the temperature of the steel liquid, use cheaper alloying elements, improve steel cleaning by reducing the addition of inclusions by ferroalloys, thus improving steel quality, increasing the efficiency of ferroalloys and increasing productivity. All this would result in lower energy consumption due to the reduction of electric furnace times and temperatures.To achieve this goal, the first experiments with 100kg castings at laboratory scale have been performed, and the results are presented here below. Castings with solid and liquid addition of the alloying elements have been made and, the performance of the elements, the use of ferroalloys of different qualities and the final solidification microstructure have been analyzed for the 95Cr6 alloy, obtaining similar results in both processes. A more complex alloy (40NiCrMo4) has also been investigated to analyze the performance of other elements like Ni and Mo. The results obtained with both alloys indicate that the viability and the necessary requirements for a future adaptation to the industrial environment of this new technology are feasible. Tests on an industrial scale are necessary for a real estimation of the savings and environmental improvements that would lead to the industrialization of this new technology.
Application of ecological risk assessment based on a novel TRIAD-tiered approach to contaminated soil surrounding a closed non-sealed landfill
(2015-05-01) Gutiérrez, Laura; Garbisu, Carlos; Ciprián, Estela; Becerril, José M.; Soto, Manu; Etxebarria, Javier; Madariaga, Juan M.; Antigüedad, Iñaki; Epelde, Lur; Tecnalia Research & Innovation; Mercado
The Ecological Risk Assessment (ERA) is a reliable tool for communicating risk to decision makers in a comprehensive and scientific evidence-based way. In this work, a site-specific ERA methodology based on the TRIAD approach was applied to contaminated soil surrounding a closed non-sealed landfill, as a case study to implement and validate such ERA methodology in the Basque Country (northern Spain). Initially, the procedure consisted of the application of a Parameter Selection Module aimed at selecting the most suitable parameters for the specific characteristics of the landfill contaminated soil, taking into consideration the envisioned land use, intended ecosystem services and nature of contaminants. Afterwards, the selected parameters were determined in soil samples collected from two sampling points located downstream of the abovementioned landfill. The results from these tests were normalized to make them comparable and integrable in a risk index. Then, risk assessment criteria were developed and applied to the two landfill contaminated soil samples. Although the lack of a proper control soil was evidenced, a natural land use was approved by the ERA (at Tier 2) for the two landfill contaminated soils. However, the existence of a potential future risk resulting from a hypothetical soil acidification must be considered.
Assessment of nanoparticles release into the environment during drilling of carbon nanotubes/epoxy and carbon nanofibres/epoxy nanocomposites
(2017-10-15) Starost, Kristof; Frijns, Evelien; Van Laer, Jo; Faisal, Nadimul; Egizabal, Ainhoa; Elizetxea, Cristina; Blazquez, Maria; Nelissen, Inge; Njuguna, James; Elizextea, Cristina; Biomateriales; POLIMEROS
The risk assessment, exposure and understanding of the release of embedded carbon nanotubes (CNTs) and carbon nanofibers (CNFs) from commercial high performance composites during machining processes are yet to be fully evaluated and quantified. In this study, CNTs and CNFs were dispersed in epoxy matrix through calendaring process to form nanocomposites. The automated drilling was carried out in a specially designed drilling chamber that allowed elimination of background noise from the measurements. Emission measurements were taken using condensed particle counter (CPC), scanning mobility particle sizer (SMPS) and DMS50 Fast Particulate Size Spectrometer. In comparison to the neat epoxy, the study results revealed that the nano-filled samples produced an increase of 102% and 227% for the EP/CNF and EP/CNT sample respectively in average particle number concentration emission. The particle mass concentration indicated that the EP/CNT and EP/CNF samples released demands a vital new perspective on CNTs and CNFs embedded within nanocomposite materials to be considered and evaluated for occupational exposure assessment. Importantly, the increased concentration observed at 10 nm aerosol particle sizes measurements strongly suggest that there are independent CNTs being released at this range.
Barriers to transitioning to a circular bio-based economy: Findings from an industrial perspective
(2024-07) Dace, Elina; Cascavilla, Alessandro; Bianchi, Marco; Chioatto, Elisa; Zecca, Emy; Ladu, Luana; Yilan, Gülşah; ECONOMÍA CIRCULAR
The transition from a linear fossil-based to a circular bio-based economy represents an opportunity and a suitable pathway for achieving several sustainable development goals. However, the transition is a complex process since it requires transformative policies, purposeful innovation, access to finance, risk-taking capacity as well as new and sustainable business models and markets. Accordingly, the first step in this transition process is the identification of barriers that are hampering the transition to a sustainable circular bio-based economy. With this motivation in mind, this study reviews grey literature to identify barriers focusing on four critical sectors facing major challenges within the current linear economy and requiring a sustainable transition most urgently: construction, chemicals, plastics, and textile sectors. Employing an adapted STEEP methodology (Social, Technological, Economical, Environmental, Political), a total of 193 different barriers have been identified and clustered under six categories: cultural, technical, economic, environmental, governance, and structural. Regardless of the sector, cultural and structural barriers are identified as the most prominent; the lack of incentives for consumer behaviour change and lack of stakeholder collaboration were the most cited barriers among the literature records. From a value chain perspective, most of the barriers are related to the material processing and product manufacturing stage. Finally, potential solutions, extracted from the grey literature, are proposed to fill the gaps and overcome the identified barriers. Many of the identified barriers are common across the four investigated sectors, indicating the solutions or measures can be applicable in a wider perspective to promote the transition in the right direction.
Benign recovery of platinum group metals from spent automotive catalysts using choline-based deep eutectic solvents
(2022) Lanaridi, Olga; Platzer, Sonja; Nischkauer, Winfried; Betanzos, Jokin Hidalgo; Iturbe, Ainhoa Unzurrunzaga; Del Rio Gaztelurrutia, Carmen; Sanchez-Cupido, Laura; Siriwardana, Amal; Schnürch, Michael; Limbeck, Andreas; Konegger, Thomas; Bica-Schröder, Katharina; VALORIZACIÓN DE RESIDUOS; Tecnalia Research & Innovation
The recovery of platinum group metals (PGMs) from secondary raw materials has become a topic of critical importance mainly due to the gradual depletion of their natural resources and their continuously increasing demand. However, the insufficient recovery of PGMs coupled with the negative environmental impact of the state-of-the-art recycling procedures mandate the investigation and development of alternative recovery processes that will assist in minimizing or even eliminating these drawbacks. Herein, we present a process for the extraction of platinum group metals from spent car catalysts relying on benign deep eutectic solvents (DESs). It is demonstrated that with addition of small amounts of an oxidizing agent, deep eutectic solvents can act as excellent leaching media for the quantitative extraction of platinum group metals. Despite its inertness towards acidic and oxidizing agents, Rh can be leached in a considerable amount which can be further increased by physical pre-treatment of the spent car catalyst material.
Biosensing strategies based on enzymatic reactions and nanoparticles
(2018-04-21) Díez-Buitrago, Beatriz; Briz, Nerea; Liz-Marzán, Luis M.; Pavlov, Valeri; Tecnalia Research & Innovation; SG
Enzymes are pivotal elements in bioanalysis due to their specificity and extremely high catalytic activity. The sensitivity of bioanalytical assays depends mainly on the capacity of an observer to detect the product(s) of a biocatalytic reaction. Both natural and artificial compounds have been traditionally used to evaluate enzymatic activities. The drawbacks of chromogenic and fluorogenic organic enzymatic substrates are their high cost and low stability, resulting in high background signals. We review here state of the art assays in the detection of enzymatic activities using recent advances in nanoscience. Novel methods based on the use of nanoparticles lead to increased sensitivity and decreased costs for bioanalysis based on enzymes as recognition elements and signal amplifiers in Enzyme-Linked Immunosorbent Assays (ELISA). Novel approaches toward the detection of enzymatic activities are based on biocatalytic synthesis, modulation, etching, and aggregation of nanoparticles under physiological conditions.
Chlorosulfonation of polystyrene substrates for bioanalytical assays: Distribution of activated groups at the surface
(2012) Del Prado, Anselmo; Briz, Nerea; Navarro, Rodrigo; Pérez, Mónica; Gallardo, Alberto; Reinecke, Helmut; SG
In this work the activation of transparent PS substrates by chlorosulfonation is described and their distribution in the subsurface region is analyzed. For this purpose XPS, FTIR-ATR and colorimetry have been used. It is shown that the electrophilic aromatic substitution of polystyrene in pure chlorosulfonic acid is extremely quick with complete surface coverage by chlorosulfonic groups achieved after only a 10 minute reaction time at -10 °C. It is further demonstrated that the reaction is very surface selective and that even after reaction times as long as 3 hours, the modification is limited to a layer with a thickness of less than one micron. The activated PS substrates can be further functionalized in a second step with carboxylic groups. Due to the excellent optical transparency that the samples maintain upon modification, the modified systems were successfully probed for use in ELISA assays.
Competitive removal of pharmaceuticals from environmental waters by adsorption and photocatalytic degradation
(2014-08-01) Rioja, N.; Benguria, P.; Peñas, F. J.; Zorita, S.; MATERIALES PARA CONDICIONES EXTREMAS; ADAPTACIÓN AL CAMBIO CLIMÁTICO
This work explores the competitive removal of pharmaceuticals from synthetic and environmental waters by combined adsorption-photolysis treatment. Five drugs usually present in waterways have been used as target compounds, some are pseudo-persistent pollutants (carbamazepine, clofibric acid, and sulfamethoxazole) and others are largely consumed (diclofenac and ibuprofen). The effect of the light source on adsorption of drugs onto activated carbons followed by photolysis with TiO2 was assessed, being UV-C light the most effective for drug removal in both deionized water and river water. Different composites prepared from titania nanoparticles and powdered activated carbons were tested in several combined adsorption-photocatalysis assays. The composites prepared by calcination at 400 °C exhibited much better performance than those synthesized at 500 °C, being the C400 composite the most effective one. Furthermore, some synthetic waters containing dissolved species and environmental waters were used to investigate the effect of the aqueous matrix on each drug removal. In general, photocatalyst deactivation was found in synthetic and environmental waters. This was particularly evident in the experiments performed with bicarbonate ions as well as with wastewater effluent. In contrast, tests conducted in seawater showed adsorption and photocatalytic degradation yields comparable to those obtained in deionized water. Considering the peculiarities of substrate competition in each aqueous matrix, the combined adsorption-photolysis treatment generally increased the overall elimination of drugs in water.
Construction and demolition waste in cement matrices as sinkholes of atmospheric pollution: Effect of the 2022 airborne dust in the Iberian Peninsula
(2024-02-15) Rubio Fernández, Virginia; Villa Mencía, Raquel Vigil de la; Rojas, Moisés Frías; García Giménez, Rosario; Moreno-Juez, Jaime; Soto García, Isabel Sonsoles de; TRAZABILIDAD CIRCULAR
The coincidence of a study on different ecocements to environmental exposition in Madrid (Spain) with the airborne dust from the Sahara desert in the same location, during the year 2022, facilitated the knowledge of the ecocement permeability to different sources of contamination. In general, mortars with a siliceous composition are more compact and less permeable to environmental particles compared to those with a calcareous composition. Binary mortars with glass have an intermediate response to pollutants and the most favorable for the incidence of contamination are ternary sulfoaluminate cements. The analysis of the ions penetration in the different cements studied has been followed by XRF, XRD-Rietveld and SEM/EDX analyses.
Correlating Electrochemical Behavior and Speciation in Neodymium Ionic Liquid Electrolyte Mixtures in the Presence of Water
(2020-09-21) Sanchez-Cupido, Laura; Pringle, Jennifer M.; Siriwardana, Amal I.; Hilder, Matthias; Forsyth, Maria; Pozo-Gonzalo, Cristina; VALORIZACIÓN DE RESIDUOS; Tecnalia Research & Innovation
Electrodeposition of rare earth metals at moderate temperature as a means to recover these critical materials from spent magnets or electric motors would be a major breakthrough to close the loop using a sustainable approach. This work highlights that neodymium electrodeposition in a phosphonium-based ionic liquid requires the presence of water in order to achieve a continuous layer of metal deposition. Herein, we describe that the nature of the Nd3+ solvation sphere being composed of both bis(trifluoromethylsulfonyl)imide (TFSI) and water determines neodymium deposition and that this process is not entirely dependent on the physicochemical properties of the electrolyte. The importance of the concentration of neodymium salt for the electrodeposition process has also been investigated, showing that 0.1 mol/kg Nd(TFSI)3/[P66614][TFSI] with 0.4 wt % water is the most promising electrolyte investigated, giving a favorable Nd3+ reduction process and better quality deposits.
Corrosion caused by the atmosphere on 1050 aluminum in the Basque country
(1993-01) Elola, A. S.; Otero, T. F.; Porro, A.; Tecnalia Research & Innovation
After exposing aluminum samples to five atmospheres (rural industrial and marine-industrial) in the Basque Country, the number and depth of the pits formed for different exposure times were measured. During the four years of exposure, sulphur dioxide and chloride ion levels, together with relative humidity and temperature, were determined. From these results, a linear increase of the pit density with time and a bilogarithmic one of the pit depth with time, were determined. An important effect of the synergistic action of SO2 and chloride in the formation and growth of pits was found. A statistical treatment is proposed to predict the pit density to be formed when the 1050 aluminum is exposed to the atmosphere.
Decellularized extracellular matrix-based 3D nanofibrous scaffolds functionalized with polydopamine-reduced graphene oxide for neural tissue engineering
(2023-09-15) Silva, Daniela M.da; Barroca, Nathalie; Pinto, Susana C.; Semitela, Ângela; de Sousa, Bárbara M.; Martins, Patrícia A.D.; Nero, Luís; Madarieta, Iratxe; García-Urkia, Nerea; Fernández-San-Argimiro, Francisco Javier; Garcia-Lizarribar, Andrea; Murua, Olatz; Olalde, Beatriz; Bdikin, Igor; Vieira, Sandra I.; Marques, Paula A.A.P.; Biomateriales; SG
One of the exciting prospects of using decellularized extracellular matrices (ECM) lies in their biochemical profile of preserved components, many of which are regeneration-permissive. Herein, a decellularized ECM from adipose tissue (adECM) was explored to design a scaffolding strategy for the challenging repair of the neural tissue. Targeting the recreation of the nano-scaled architecture of native ECM, adECM was first processed into nanofibers by electrospinning to produce bidimensional platforms. These were further shaped into three-dimensional (3D) nanofibrous constructs by gas foaming. The conversion into a 3D microenvironment of nanofibrous walls was assisted by blending the adECM with lactide-caprolactone copolymers, wherein tuning the adECM/copolymer ratio along with the amount of caprolactone in the copolymer led to modulating the mechanical properties towards soft, yet structurally stable, 3D constructs. In view of boosting their performance to guide neural stem cell fate, adECM-based platforms were doped with a bioinspired surface modification relying on polydopamine-functionalized reduced graphene oxide (PDA-rGO). These adECM-based 3D constructs revealed a permissive microenvironment for neural stem cells (NSCs) to adhere, grow, and migrate throughout the microporosity, owing to the synergy between the unique biochemical features of the adECM and the nanofibrous architecture. NSC responded differently depending on the adECM-based architecture–nanofibrous bidimensional, or 3D design. The 3D spatial arrangement of the nanofibers – induced by the gas foaming – exhibited a remarkable effect on NSCs’ phenotype determination and neurite formation, thereby reinforcing the critical importance of engineering scaffolds with multiple length-scale architecture. Furthermore, PDA-rGO promoted the differentiation of NSC towards the neuronal lineage. Specifically in 3D, it significantly increases the levels of Tuj1 and MAP2 a/b isoforms, confirming its effectiveness in boosting neuronal differentiation and neuritogenesis.
Design of a photoelectrochemical lab-on-a-chip immunosensor based on enzymatic production of quantum dots in situ
(2022-04-22) Díez-Buitrago, Beatriz; Fernández-San Argimiro, Francisco Javier; Lorenzo, Jaione; Bijelic, Goran; Briz, Nerea; Pavlov, Valeri; Tecnalia Research & Innovation; Biomateriales; Mercado; SG
In this work we report the development and validation of a photoelectrochemical immunosensor on the basis of alkaline phosphatase (ALP)-linked immunoassay for the detection of human serum albumin as a model analyte. In this biosensor, oriented immobilization of capture antibodies on aminated polystyrene was achieved via physical adsorption. After the interaction with the analyte, ALP immobilised on the surface through the sandwich immunoassay catalyses the hydrolysis of sodium thiophosphate (TP) to hydrogen sulphide (H2S) which in the presence of cadmium ions yields CdS quantum dots (QDs). The electrical current is generated in the course of the photoelectrochemical process (PEC) during irradiation of the CdS QDs with a UV LED (365 nm) on home-made screen-printed carbon electrodes modified with a conductive polymer. Reaction time, steps and volumes were optimized for the miniaturization of the process in order to develop a lab-on-a-chip platform. The microfluidic system was designed with optimised parameters to fabricate the immunosensor combining the immunoassay with PEC detection. The final system presents a sensitivity comparable to that of the commercial kit thanks to the signal amplification enabled by the enzymatic growth of CdS QDs in situ. This photoelectrochemical immunosensing strategy potentially opens up a new avenue for the detection of a wide range of analytes of interest due to the universal and effective enzymatic signal amplification method. Moreover, the developed bioanalytical device allows for a great reduction of time and reagents compared to exiting commercial assays, making it suitable for point-of-care applications.
Development of a biocidal treatment regime to inhibit biological growths on cultural heritage: BIODAM
(2008-12) Young, M. E.; Alakomi, H. L.; Fortune, I.; Gorbushina, A. A.; Krumbein, W. E.; Maxwell, I.; McCullagh, C.; Robertson, P.; Saarela, M.; Valero, J.; Vendrell, M.; Dirección General
Existing chemical treatments to prevent biological damage to monuments often involve considerable amounts of potentially dangerous and even poisonous biocides. The scientific approach described in this paper aims at a drastic reduction in the concentration of biocide applications by a polyphasic approach of biocides combined with cell permeabilisers, polysaccharide and pigment inhibitors and a photodynamic treatment. A variety of potential agents were screened to determine the most effective combination. Promising compounds were tested under laboratory conditions with cultures of rock deteriorating bacteria, algae, cyanobacteria and fungi. A subsequent field trial involved two sandstone types with natural biofilms. These were treated with multiple combinations of chemicals and exposed to three different climatic conditions. Although treatments proved successful in the laboratory, field trials were inconclusive and further testing will be required to determine the most effective treatment regime. While the most effective combination of chemicals and their application methodology is still being optimised, results to date indicate that this is a promising and effective treatment for the control of a wide variety of potentially damaging organisms colonising stone substrates.
Development of highly permeable ultra-thin Pd-based supported membranes
(2016-12-01) Fernandez, Ekain; Sanchez-Garcia, Jose Angel; Melendez, Jon; Spallina, Vincenzo; van Sint Annaland, Martin; Gallucci, Fausto; Pacheco Tanaka, D. A.; Prema, Radha; TECNOLOGÍAS DE HIDRÓGENO; Tecnalia Research & Innovation; TECNOLOGÍA DE MEMBRANAS E INTENSIFICACIÓN DE PROCESOS
This paper reports the preparation and characterization of ultra-thin (∼1 μm thick) Pd-based supported membranes for hydrogen purification. Ultra-thin membranes have been prepared by a combination of PVD magnetron sputtering and electroless plating techniques. The membranes have been characterized for single gas and mix gas permeation at temperatures between 350 and 500 °C and they have shown to exhibit very high hydrogen fluxes combined with a good perm-selectivity (H2/N2 ≈ 500). These results have been compared with the performance of highly permeable membranes reported in the literature. The influence of the morphology of the deposited Pd-based layers on the membrane performance has been investigated and discussed.
Dynamic behaviour of integrated chemical looping process with pressure swing adsorption in small scale on-site H2 and pure CO2 production
(2022-01-15) Argyris, Panagiotis Alexandros; Wright, Andrew; Taheri Qazvini, Omid; Spallina, Vincenzo; Tecnalia Research & Innovation
The design of a fully integrated Chemical looping reforming (CLR), single adiabatic water gas shift reactor (WGSR) and Pressure swing adsorption (PSA) operated under dynamic conditions for small scale H2 generation with inherent pure CO2 production is carried out. The dynamically operated packed bed reactors taking part in the chemical looping process have been modelled, designed and simulated to operate with transient feeds from an integrated PSA unit used for the production of 130 Nm3/h of pure H2 (99.9999% purity). As by-product, 51 Nm3/h of pure CO2 (>98.8% purity) is also produced. A rapid cycle 8-bed configuration increases the H2 recovery by 4% whilst reducing the tail gas buffer tank volume requirement by 44%. The effect of the PSA dynamic tail gas composition used as fuel for the CLR reduction reactor stage was found negligible regarding the continuity of the process and the performance of the plant, as it affected only the reduction outlet gas composition profile but had little effect on the reactor bed temperature profile. With respect to the design of the chemical looping reactor beds, an analysis has been performed on the effect of heat losses showing that at higher heat transfer coefficient (U = 5.0 W∙m−2∙K−1) CH4 conversion decreased significantly (≈90% compared to adiabatic operation), therefore a different strategy was implemented. The overall study demonstrates the process design feasibility for producing blue H2 or renewable H2 from methane/bio-methane in decentralised and modular units.
Effect of high-density current electropulsing on corrosion cracking of titanium aluminide intermetallic
(2021-07) Babutskyi, Anatolii; Chrysanthou, Andreas; Chyzhyk, Ganna; de Cortázar, Maider García; Egizabal, Pedro; Smelina, Marija; CIRMETAL; Tecnalia Research & Innovation
The effect of electropulsing on the corrosion cracking of titanium aluminide produced by self-propagating high-temperature synthesis has been investigated. The electropulsing treatment led to improved corrosion resistance in sodium fluoride solution and also eliminated corrosion cracking at the α2/γ interface during corrosion in a solution of nitric and hydrofluoric acids. This behavior was attributed to thermal and athermal effects resulting from electropulsing and leading to the interaction of conduction electrons with the defect structure. The effect of magnetic field accompanying electropusling on depinning of dislocations also has been discussed. Support for this is provided on the basis of X-ray diffraction analysis and microhardness testing.
The effect of nanosilica (SiO2) and nanoalumina (Al2O3) reinforced polyester nanocomposites on aerosol nanoparticle emissions into the environment during automated drilling
(2017-05) Starost, Kristof; Frijns, Evelien; Van Laer, Jo; Faisal, Nadimul; Egizabal, Ainhoa; Elizetxea, Cristina; Nelissen, Inge; Blázquez, María; Njuguna, James; Biomateriales; POLIMEROS
The aim of this study is to investigate the effect nanosilica and nanoalumina has on nanoparticle release from industrial nanocomposites due to drilling for hazard reduction whilst simultaneously obtaining the necessary mechanical performance. This study is therefore specifically designed such that all background noise is eliminated in the measurements range of 0.01 particles/cm3 and ±10% at 106 particles/cm3. The impact nano-sized SiO2 and Al2O3 reinforced polyester has on nanoparticle aerosols generated due to drilling is investigated. Real-time measurement was conducted within a specially designed controlled test chamber using a condensation particle counter (CPC) and a scanning mobility particle sizer spectrometer (SMPS). The results show that the polyester nanocomposite samples displayed statistically significant differences and an increase in nanoparticle number concentration by up to 228% compared to virgin polyester. It is shown that the nanofillers adhered to the polyester matrix showing a higher concentration of larger particles released (between 20 – 100 nm). The increase in nanoparticle reinforcement weight concentration and resulting nanoparticle release vary considerably between the nanosilica and nanoalumina samples due to the nanofillers presence. This study indicates a future opportunity to safer by design strategy that reduces number of particles released concentration and sizes without compromising desired mechanical properties for engineered polymers and composites.
Efficient Ullmann and Suzuki-Miyaura cross-coupling reactions catalyzed by heterogeneous Pd-porous carbon beads catalysts in aqueous media
(2022-12) Khosravi, Faezeh; Centeno-Pedrazo, Ander; Rajabi, Fatemeh; Len, Thomas; Voskressensky, Leonid G.; Luque, Rafael; Garcia-Suarez, Eduardo J.; Tecnalia Research & Innovation
Carbon-carbon coupling reactions are of great interest for a wide range of applications including pharmaceutical compounds and biologically active molecules. Usually, coupling reactions were performed using a homogeneous catalyst and organic solvent. Thus, the use of greener solvents as well as the heterogenization of the classical metal-based catalyst are desirable and still under development. This contribution describes the synthesis of biaryl compounds in water by Ullmann and Suzuki reactions with carbon-supported Pd nanoparticles. As expected, the microwave activation method drastically decrease the reaction time. The utilization of trioctylphosphine (TOP) or triphenylphosphine (TPP) ligands slow down the Pd leaching without cancelling it compared to the unliganded Pd catalyst. Moreover, a treatment with H2O2 appears beneficial with respect to a thermal-oxidative treatment at 1500 °C due to higher hydrophilicity of the resultant carbon support. These results and methodology contribute to a greener future for C–C coupling reactions.

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