Hybrid cobalt ferrite/carbon catalysts: synthesis, characterization and applications in water treatment

Mestrado de dupla diplomação com a UTFPR - Universidade Tecnológica Federal do ParanáThis work deals with the development of carbon-coated magnetic cobalt ferrite nanoparticles as catalysts for the treatment of water containing Contaminants of Emerging Concern (CEC) by Catalytic Wet Peroxide Oxidation (CWPO), using paracetamol (PCM) as model pollutant. For this purpose, a magnetic core (CoFe2O4) is developed by the sol-gel method, the core is subsequently coated with a resin prepared from formaldehyde, resorcinol and tetraethyl orthosilicate (TEOS), and later carbonized by pyrolysis at 600 °C under a N2 atmosphere. Afterwards, the silica generated from TEOS is removed by etching with NaOH to create a void inside the particle, creating a yolk-shell shape denoted as CoFe2O4@void@C. XRD, TEM and FTIR analysis revealed that the uncoated core is composed by a CoFe2O4 cubic spinel structure with space group Fd-3m and a crystallite size of 53 nm, calculated using the W-H method, that matches very well with the average size observed by TEM equals to 53.51 4.2 nm. The average size of the nanoparticles for the hybrid coated ferrite increases to 58.7 8.1 nm. After the preparation of the catalysts, reaction runs were performed to assess its suitability for the degradation of PCM by CWPO. The concentration of paracetamol, hydrogen peroxide and Total Organic Carbon (TOC) were recorded against the reaction time. The performance of the CoFe2O4@void@C catalyst was compared to that of the uncoated ferrite, the CoFe2O4 and CoFe2O4@void@C materials allowing TOC values of 46 and 58% respectively at 24h. The hybrid coated ferrite succeeds in avoid iron leaching and to be a stable catalyst. The amount of leached iron at the end of the treatment was equal to 1.59 mg·L-1, which is within the limit concentration of 2 mg·L-1 of iron allowed in waters, as established EU regulations. A kinetic model was proposed describing the decomposition of hydrogen peroxide and the removals of the pollutant PCM and TOC with the CoFe2O4@void@C as catalyst, applying an empirical kinetic model composed of a second-order and an autocatalytic expression to describe the decomposition of H2O2 and PCM, respectively. The kinetic model for TOC can be well-described as a sum of the initial pollutant plus the oxidation intermediates from the PCM and the organic components that are refractory to the process.Este trabalho trata do desenvolvimento de nanopartículas magnéticas de ferrita de cobalto revestidas com carbono como catalisadores para o tratamento de água contendo contaminantes de preocupação emergente por oxidação catalítica por peróxido úmido (CWPO), usando paracetamol (PCM) como poluente modelo. Para o efeito foi inicialmente sintetizado um núcleo magnético pelo método sol-gel, revestido de seguida com uma resina preparada a partir de formaldeído, resorcinol e tetraethyl orthosilicate (TEOS), posteriormente carbonizada por pirólise a 600 °C sob atmosfera de N2. Subsequentemente, a sílica gerada a partir de TEOS é removida com NaOH para criar um vazio entre o núcleo e o revestimento, criando uma estrutura de nanopartícula denominada de casca de gema, denotada como CoFe2O4@void@C. As análises de XRD, TEM e FTIR revelaram que o núcleo é composto por uma estrutura espinélica cúbica de CoFe2O4 com grupo espacial Fd-3m e tamanho de cristalito de 53 nm, calculado usando o método WH que corrobora com o tamanho médio observado por TEM igual a 53.51 4.2 nm. O tamanho médio das nanopartículas de ferrite recoberta aumentam para 58.7 8.1 nm. Os catalisadores preparados foram testados na degradação de PCM por CWPO. As concentrações de paracetamol, peróxido de hidrogénio e Carbono Orgânico Total (TOC) foram registradas em função do tempo de reação, sendo o desempenho do catalisador CoFe2O4@void@C comparado com o da ferrite não revestida. Os catalisadores CoFe2O4 e CoFe2O4@void@C alcançaram valores de TOC de 46 e 58% respectivamente, após 24h de reação. No ensaio realizado com a ferrite revestida observou-se uma lixiviação de ferro 1.59 mg·L-1, provando ser um catalisador estável, estando a quantidade de ferro no final do ensaio dentro da concentração limite de 2 mg·L-1 de ferro permitido em águas, como estabelecido pela legislação da União Europeia. Foi definido um modelo cinético que descreve a decomposição de peróxido de hidrogénio e as remoções do poluente PCM e de TOC, considerando o CoFe2O4@void@C como catalisador. Foi aplicado um modelo cinético empírico composto por uma expressão de segunda ordem e uma expressão autocatalítica para descrever a decomposição de H2O2 e PCM, respectivamente. O modelo cinético para a evolução de TOC pode ser bem descrito como a soma do poluente inicial mais os intermediários de oxidação do PCM e os componentes orgânicos refratários ao processo.This work is a result of Project “RTChip4Theranostics – Real-time Liver-on-a-chip platform with integrated micro(bio)sensors for preclinical validation of graphene-based magnetic nanocarriers towards cancer theranostics”, with the reference NORTE-01-0145-FEDER-029394, supported by Norte Portugal Regional Operational Programme (NORTE 2020), under the Portugal 2020 Partnership Agreement, through the European Regional Development Fund (ERDF); and CIMO (UIDB/00690/2020) through FEDER under Program PT202

Dimensionat d'un gasificador de biomassa de petita potència i estudi d'implantació en una microxarxa mitjançant matpower

El següent treball està fet en col·laboració amb el projecte del CITCEA-UPC, en el que es pretén trobar la metodologia de dimensionat d’un gasificador de biomassa per la producció de gas combustible. Així doncs, aquest treball recull l’estudi de tots els factors que influencien en la instal·lació de gasificadors de biomassa de petita potència en una microxarxa; des de l’estudi del funcionament del sistema de gasificació i la justificació del dimensionat de totes les parts del gasificador, fins a l’estudi dels canvis en els fluxos de potència a la xarxa de distribució i a la microxarxa degut a la connexió dels gasificadors i així conèixer la quantitat i distribució òptima d’aquests a la microxarxa. La gasificació de biomassa i l’obtenció d’electricitat a partir del gas produït és un procés molt complex, és per això que al treball s’inclouen apartats en els que es descriuen els requeriments per a poder obtenir electricitat un cop creat el gas; com ara els diferents mètodes de neteja als que es pot sotmetre el gas, i el tipus de motor idoni per a l’operació amb gas pobre i les respectives modificacions en aquest necessàries per a l’operació. Actualment al CITCEA-UPC es disposa d’un prototip de gasificador de biomassa amb el que s’han anat fent proves experimentals al llarg de l’elaboració d’aquest projecte per tal d’aplicar i validar els coneixements adquirits i obtenir gas combustible

Про водогосподарський комплекс Криму

В статье дается определение понятия "водохозяйственный комплекс региона". Приводятся количественные и качественные характеристики состояния развития этой отрасли в АРК. Делаются выводы и предложения относительно повышения эффективности функционирования отрасли, улучшению качества предоставляемых услуг.У статті дається визначення поняття "водогосподарський комплекс регіону". Приводяться кількісні і якісні характеристики стану розвитку цієї галузі в АРК. Робляться висновки й пропозиції щодо підвищення ефективності функціонування галузі, поліпшенню якості надаваних послуг.There is given the definition of concept "a water complex of the region" in this article. Quantitative are resulted and qualitative behaviors of a condition of development of this area in АRК. The conclusions and proposals concerning increase of efficiency of operation of area, improvement of the quality of rendered services are done

NMR as evaluation strategy for cellular uptake of nanoparticles

Advanced nanostructured materials, such as gold nanoparticles, magnetic nanoparticles, and multifunctional materials, are nowadays used in many state-of-the-art biomedical application. However, although the engineering in this field is very advanced, there remain some fundamental problems involving the interaction mechanisms between nanostructures and cells or tissues. Here we show the potential of 1H NMR in the investigation of the uptake of two different kinds of nanostructures, that is, maghemite and gold nanoparticles, and of a chemotherapy drug (Temozolomide) in glioblastoma tumor cells. The proposed experimental protocol provides a new way to investigate the general problem of cellular uptake for a variety of biocompatible nanostructures and drugs. © 2014 American Chemical Society

Diagnóstico de los factores psicosociales y sus efectos en el trabajo para los conductores de la empresa líneas Timanco S.A.S.

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Coisas inventadas: montagem e edição em um cineclube escolar

The present article is based on the experience of child education teachers in montage of short films carried out in schools in the outskirts of Campinas-SP. These experiences express a path that emerged in the cartographic research developed in the project Lugar-escola e cinema (Place-school and cinema), and led us to rehearse the perspective of montage as ignorant schoolmaster of a pedagogy of cinema. The article begins by indicating the need to distinguish the concepts of editing and montage, due to the singularities of the school context and the way cinema is produced there. Then, it reports and reflects on processes of individual and collective film creation, where montage and editing act distinctly in negotiations between teachers-filmmakers and in learning from and with cinema. Since these processes are as multiple as they are intuitive, the article reports in what way intuition combined with technical knowledge led to a certain type of montage, where the spread of senses and confidence in the viewer play a decisive role in our experience of making-seeing-talking about films in a school cine club.Este artigo demonstra parte da experiência de professoras e professores da educação infantil com montagem e edição de pequenos filmes realizados em escolas da periferia de Campinas – SP. Essas experiências expressam um traçado que emergiu na pesquisa cartográfica, desenvolvida no Projeto Lugar-escola e cinema, e levaram a ensaiar a perspectiva da montagem como mestre ignorante de uma pedagogia do cinema. Inicialmente, distingue-se os conceitos de montagem e edição, devido às singularidades do contexto escolar e do modo como o cinema é ali produzido. Em seguida, relata-se e reflete-se acerca de alguns processos de criação individual e coletiva de filmes em que montagem e edição operam distintamente nas negociações entre docentes-cineastas e no aprendizado com e do cinema. Sendo esses processos tão múltiplos quanto intuitivos, o artigo relata como a intuição aliada ao conhecimento técnico levou a certo tipo de montagem, na qual a proliferação de sentidos e a confiança no espectador atuam de maneira decisiva em nossa experiência de fazer-ver-conversar em um cineclube escolar

Low-temperature anomalies in muon spin relaxation of solid and hollow nanoparticles: a pathway to detect unusual local spin dynamics

By means of muon spin relaxation measurements we unraveled the temperature spin dynamics in monodisperse maghemite spherical nanoparticles with different surface to volume ratio, in two samples with a full core (diameter D∼4 and D∼5nm) and one with a hollow core (external diameter D∼7.4nm). The behavior of the muon longitudinal relaxation rates as a function of temperature allowed us to identify two distinct spin dynamics. The first is well witnessed by the presence of a characteristic peak for all the samples around the so-called muon blocking temperature T$_{B}^{μ+}$. A Bloembergen-Purcell-Pound (BPP)-like model reproduces the experimental data around the peak and at higher temperatures (20<T<100K) by assuming the Néel reversal time of the magnetization as the dominating correlation time. An additional dynamic emerges in the samples with higher surface to volume ratio, namely, full 4 nm and hollow samples. This is witnessed by a shoulder of the main peak for T<20K at low longitudinal field (μ$_{0}$H≈15mT), followed by an abrupt increase of the relaxation rate at T<10K, which is more evident for the hollow sample. These unusual anomalies of the longitudinal relaxation rate for T<T$_{B}^{μ+}$ are suggested to be due to the surface spins’ dynamical behavior. Furthermore, for weak applied longitudinal magnetic field (μ$_{0}$H≈15mT) and T<T$_{B}^{μ+}$ we observed damped coherent oscillations of the muon asymmetry, which are a signature of a quasistatic local field at the muon site as probed by muons implanted in the inner magnetic core of the nanoparticles. The muon spin relaxation technique turns out to be very successful to study the magnetic behavior of maghemite nanoparticles and to detect their unusual local spin dynamics in low magnetic field conditions

Rhenium-catalyzed insertion of terminal alkenes into a C(sp(2))–H bond and successive transfer hydrogenation

Treatment of aromatic aldimines with terminal alkenes in the presence of a rhenium catalyst, [HRe(CO)(4)](n), gives 2-alkenylbenzylamines in good to excellent yields. This reaction proceeds via the insertion of the alkene into a C-H bond at the ortho-position of the imino group of the aromatic aldimine followed by sequential beta-hydride elimination from the formed alkyl rhenium intermediate and then by hydrogenation of the imino group of the aldimine

Magneto-Luminescence Correlation in the Textbook Dysprosium(III) Nitrate Single-Ion Magnet

Multifunctional Single-Molecule Magnets (SMMs) or Single-Ion Magnets (SIMs) are intriguing molecule-based materials presenting an association of the slow magnetic relaxation with other physical properties. In this article, we present an example of a very simple molecule based on Dy3+ ion exhibiting a field induced SIM property and a characteristic Dy3+ based emission. The [Dy(NO3)(3)(H2O)(4)]center dot 2H(2)O (1) complex is characterized by the means of single crystal X-Ray diffraction and their magnetic and photo-luminescent properties are investigated. We demonstrate here that it is possible to correlate the magnetic and luminescent properties and to obtain the Orbach barrier from the low temperature emission spectra, which is often difficult to properly extract from the magnetic measurements, especially in the case of field induced SIMs

Controlled Anchoring of Iron-Oxide Nanoparticles on Polymeric Nanofibers: Easy Access to Core@Shell Organic-Inorganic Nanocomposites for Magneto-Scaffolds

Composites combining superparamagnetic iron oxide nanoparticles (SPIONs) and polymers are largely present in modern (bio)materials. However, while SPIONs embedded in polymer matrices are classically reported, the mechanical and degradation properties of the polymer scaffold are impacted by the SPIONs. Therefore, the controlled anchoring of SPIONs onto polymer surfaces is still a major challenge. Herein, we propose an efficient strategy for the direct and uniform anchoring of SPIONs on the surface of functionalized-polylactide (PLA) nanofibers via a simple free ligand exchange procedure to design PLA@SPIONs core@shell nanocomposites. The resulting PLA@SPIONs hybrid biomaterials are characterized by electron microscopy (SEM and TEM) and EDXS analysis, to probe the morphology and detect elements present at the organic/inorganic interface, respectively. A monolayer of SPIONs with a complete and homogeneous coverage is observed on the surface of PLA nanofibers. Magnetization experiments show that magnetic properties of the nanoparticles are well-preserved after their grafting on the PLA fibers and that the size of the nanoparticles does not change. The absence of cytotoxicity, combined with a high sensitivity of detection in MRI both in vitro and in vivo make these hybrid nanocomposites attractive for the development of magnetic biomaterials for biomedical applications