This work reports the treatment of crystallized-fruit effluents, characterized by a very low biod... more This work reports the treatment of crystallized-fruit effluents, characterized by a very low biodegradability (BOD5/COD <0.19), through the application of a UV-A LED photo-Fenton process. Firstly, a Box-Behnken design of Response Surface Methodology was applied to achieve the optimal conditions for the UV-A LED photo-Fenton process, trying to maximize the efficiency by saving chemicals and time. Under the optimal conditions ([H2O2] = 5459 mg/L; [Fe(3+)] = 286 mg/L; time >180 min), a COD removal of 45, 64 and 74% was achieved after 360 min, using an irradiance of 23, 70 and 85 W/m(2) respectively. Then a combination of UV-A LED photo-Fenton with coagulation-flocculation-decantation attained a higher COD removal (80%), as well as almost total removal of turbidity (99%) and total suspended solids (95%). Subsequent biodegradability of treated effluents increased, allowing the application of a biological treatment step after the photochemical/CFD with 85 W/m(2).
Journal of Nanoscience and Nanotechnology, Oct 1, 2011
The application of nanocoatings in the textile finishing is increasingly being explored because t... more The application of nanocoatings in the textile finishing is increasingly being explored because they open a whole new vista of value-addition possibilities in the textile sector. In the present work, low temperature pulsed DC magnetron sputtering method was used to create functional TiO2 nanocoatings on poly(lactic acid) textile fibres surfaces. In this study, the principal objectives in the application of TiO2 nanocoatings to textile materials are to impart UV protection functions and self-cleaning properties to the textile substrates. The TiO2 films were characterized by X-ray diffraction, scanning electron microscopy, atomic force microscopy, transmission electron microscopy, UV-visible spectroscopy and contact angle analysis. The Photocatalytic activity of the films was tested by measuring the photodegradation rates of rhodamine-B dye aqueous solution under UV light irradiation. The ultraviolet protection function was tested according to the Australian/New Zealand standards. It was observed that the TiO2 nanocoatings on poly(lactic acid) fibres showed an excellent ultraviolet protection (> 40) function and the photocatalytic efficiency was maintained even after a strong washing treatment.
ABSTRACT Continuous Production of Magnetic and Metal-Organic Nanoparticles with NETmix Reactor M.... more ABSTRACT Continuous Production of Magnetic and Metal-Organic Nanoparticles with NETmix Reactor M. Enis Leblebicia, Carlos M. Fontea, Marcelo F. Costaa, Filipe Ataídeb, M. Paz Garciac, Viviana Silvaa, Thomas Devicd, Patricia Horcajadad, Pedro Tavarese, João Pedro Araújoc, Rui Oliveirab, Joaquim L. Fariaa, Madalena M. Diasa, Jos Carlos B. Lopes*a aLaboratory of Separation and Reaction Engineering, Faculty of Engineering, University of Porto, Porto, Portugal bREQUIMTE/CQFB, Departamento de Química, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, Caparica, Portugal cIFIMUP/Departamento de Física, Universidade do Porto, Porto, Portugal dInstitut Lavoisier (CNRS 8180) Institut universitaire de France, Universit de Versailles, Versailles, France eCQVR, Departamento de Química, Universidade de Trás-os-Montes e Alto Douro, Vila Real, Portugal *e-mail: lopes@fe.up.pt More than half a century passed over the legendary lecture of Professor Richard Feynman, “There’s Plenty of Room at the Bottom” which is usually referred as the muse of nanotechnology. Today, nano-scale products find there way into a variety of promising services from more humane cancer treatments to increasing computer power/capacity, while their production scales are getting from laboratory towards industrial [1]. Chemical coprecipitation in batch stirred vessels has been a suitable, low-energy method to achieve nanometer scale crystals. However the focus now is not only to produce nanoparticles, but to control the particle size with a narrow particle size distribution (PSD). [2, 3]. Since coprecipitation in general results in wide PSD, high energy methods such as thermal decomposition, hydrothermal, and microwave synthesis were proposed and have been shown effective for size control of nanoparticles [2]. However, the productivity and scalability of these methods are lower than coprecipitation. Coprecipitation is done by vigorously mixing two or more reactant solutions, resulting in a product, which has low solubility in the medium. This supersaturated medium results in immediate nucleation [4] and particle growth. To produce uniform particles, it is crucial to keep a homogeneous concentration of the precursor molecules/clusters throughout the medium from the moment the reactant solutions contact until the end of the particle growth stage. Maintaining the homogeneity is the reason for the vigorous mixing in stirred vessels where batch coprecipitation takes place and it is the key factor on product quality, namely the PSD and on the energy input of the process. This work revisits coprecipitation method focusing on continuous production of magnetic nanoparticles (MNP) and metal – organic frameworks (MOFs) with high productivity without compromising PSD. The aim is to produce MNP and MOFs nanoparticles on a continuous reactor, namely the NETmix Reactor. The NETmix Reactor is a new technology consisting of a network of mixing chambers interconnected by transport channels [5]. Networks are generated by the repetition of unit cells where each unit cell consists of one chamber and two inlet and two outlet channels oriented at a 45º angle from the main flow direction. Above a critical channel Reynolds number, the system evolves to a self-sustained oscillatory laminar flow regime inside the mixing chambers inducing local strong laminar mixing. This network system of identical units, results in a flexible static mixer, which can be scaled-up easily without changing the design of mixing units. Magnetite synthesis with NETmix reactor was performed by mixing an aqueous solution of Fe2+ and Fe3+ salts with a base solution continuously to result in a pH value of 9.5 under inert atmosphere and 45°C. Trisodium citrate was used to stabilize particles. At this temperature and pressure, the solubility of magnetite is of order of 10-8 mol/kg the solubility of water [6]. This degree of supersaturation favors nucleation rather than particle growth therefore resulting in small crystals. Maturation time of 10 minutes was proven sufficient to ensure total conversion of iron salts to magnetite crystals. The washed crystals were characterized using dynamic light scattering, X-Ray diffraction, high-resolution transmission electron microscopy, Raman spectroscopy and supercooled quantum interference device. The pure magnetite crystals were found to be 4.8±0.25 nm, monocrystalline and superparamagnetic. The space-time yield of the process was 4.3 tons/m3/day. Two different iron-based metal-organic frameworks were also synthesized using the NETmix reactor namely iron fumarate MIL-88A [7] and iron trimesate MIL-100 [8]. An equilibrium model for iron (III) and the polycarboxylic acids was developed, in order to avoid formation of amourphous phases thus eliminating kinetic limitations. In this way, the nucleation of the MOFs is fast, which is further favored by the immediate homogenization provided by NETmix reactor which resulted in smaller and more uniform particles.…
ABSTRACT A PRESENTE INVENÇÃO REFERE-SE A NOVOS CATALISADORES HÍBRIDOS DE VANÁDIO DE FÓRMULA GERAL... more ABSTRACT A PRESENTE INVENÇÃO REFERE-SE A NOVOS CATALISADORES HÍBRIDOS DE VANÁDIO DE FÓRMULA GERAL I EM QUE:N=1 A 4;R1 E R2 SÃO INDEPENDENTES PODENDO SER DIFERENTES OU IGUAIS E PODEM SER -H, -X (HALOGÉNEO), C1 A C4 ALQUIL LINEAR OU RAMIFICADO, -NO2, -OH, -OME, -OET E; A É UM MATERIAL SUPORTE COM GRUPOS FUNCIONAIS OH NA SUA SUPERFÍCIE.A PRESENTE INVENÇÃO INCORPORA TAMBÉM A APLICAÇÃO DESTES COMPLEXOS EM PROCESSOS DE OXIDAÇÃO SELECTIVA DE CICLOALCANOS PARA PRODUZIR ÁLCOOIS E CETONAS CÍCLICAS. QUANDO APLICADOS NO PROCESSO DE OXIDAÇÃO, OS NOVOS CATALISADORES DE VANÁDIO PERMITEM UMA CONVERSÃO E SELECTIVIDADE ELEVADAS PARA OS PRODUTOS DE REACÇÃO CORRESPONDENTES, ATRAVÉS DO DIOXIGÉNIO (O2), OXIDANTE BARATO, DISPONÍVEL NO AR, SOB CONDIÇÕES DE REACÇÃO MODERADAS, QUER NA PRESENÇA OU NA AUSÊNCIA DE ÁCIDOS HETEROCÍCLICOS.
ABSTRACT Volatile organic compounds (VOC) are harmful environmental pollutants originated from st... more ABSTRACT Volatile organic compounds (VOC) are harmful environmental pollutants originated from stationary and mobile sources, such as painting, printing, petroleum refineries, fuel storage and motor vehicles. As some VOCs are dangerous to human health and to the environment, their emissions are regulated. Catalytic oxidation to CO2 and water is an environmentally friendly technology for VOC abatement. It requires low temperatures (around 250-500 °C) and causes less NOx formation, compared to conventional thermal oxidation, which requires high operation temperatures (650-1100 °C). Metal oxides can be used as heterogeneous catalysts for VOC oxidation. Commonly used catalysts include manganese, copper, nickeland iron oxides. It has been reported that although metal oxide based catalysts are less active than supported precious metals in oxidizing VOC streams, they are generally more resistant to poisoning phenomena. However, mixed oxides can show good activities in catalytic oxidation of VOCs, thus being good candidates for this application. In this work, single oxides of lanthanum and nickel were used. Mixed oxide samples of La-Ni-O synthesized by an evaporation method, with La-Ni ratios of 1:1 and 1:2 were also evaluated. Catalyst samples were characterised by N2 adsorption at -196 °C, temperature programmed reduction, scanning electron microscopy and X-ray diffraction. The materials were tested in the oxidation of ethyl acetate, a compound widely used as a solvent in printing operations, glues, nail polish removers, etc. It was found that the mixed oxide was much more active that the single oxide catalysts, allowing 100 % conversion of the VOC into CO2 at ~250 °C, with no formation of CO. Full conversion was not achieved by any of the single oxides, and CO was detected. The La:Ni 1:2 sample was more active than the 1:1 analogue. The 1:2 mixed oxide had a much larger surface area and also easier reducibility than the 1:1 sample. Both mixed oxides had larger surface area and higher reducibility than the single components, which can explain their improved performance.
A commercial iron oxide support is compared with Fe 2 O 3 samples prepared by decomposition of ir... more A commercial iron oxide support is compared with Fe 2 O 3 samples prepared by decomposition of iron nitrate, at 300 C and 500 C and heating times varying from 30 min to 96 h in N 2. Different methods were used for gold deposition, namely double impregnation ...
This work reports the treatment of crystallized-fruit effluents, characterized by a very low biod... more This work reports the treatment of crystallized-fruit effluents, characterized by a very low biodegradability (BOD5/COD <0.19), through the application of a UV-A LED photo-Fenton process. Firstly, a Box-Behnken design of Response Surface Methodology was applied to achieve the optimal conditions for the UV-A LED photo-Fenton process, trying to maximize the efficiency by saving chemicals and time. Under the optimal conditions ([H2O2] = 5459 mg/L; [Fe(3+)] = 286 mg/L; time >180 min), a COD removal of 45, 64 and 74% was achieved after 360 min, using an irradiance of 23, 70 and 85 W/m(2) respectively. Then a combination of UV-A LED photo-Fenton with coagulation-flocculation-decantation attained a higher COD removal (80%), as well as almost total removal of turbidity (99%) and total suspended solids (95%). Subsequent biodegradability of treated effluents increased, allowing the application of a biological treatment step after the photochemical/CFD with 85 W/m(2).
Journal of Nanoscience and Nanotechnology, Oct 1, 2011
The application of nanocoatings in the textile finishing is increasingly being explored because t... more The application of nanocoatings in the textile finishing is increasingly being explored because they open a whole new vista of value-addition possibilities in the textile sector. In the present work, low temperature pulsed DC magnetron sputtering method was used to create functional TiO2 nanocoatings on poly(lactic acid) textile fibres surfaces. In this study, the principal objectives in the application of TiO2 nanocoatings to textile materials are to impart UV protection functions and self-cleaning properties to the textile substrates. The TiO2 films were characterized by X-ray diffraction, scanning electron microscopy, atomic force microscopy, transmission electron microscopy, UV-visible spectroscopy and contact angle analysis. The Photocatalytic activity of the films was tested by measuring the photodegradation rates of rhodamine-B dye aqueous solution under UV light irradiation. The ultraviolet protection function was tested according to the Australian/New Zealand standards. It was observed that the TiO2 nanocoatings on poly(lactic acid) fibres showed an excellent ultraviolet protection (> 40) function and the photocatalytic efficiency was maintained even after a strong washing treatment.
ABSTRACT Continuous Production of Magnetic and Metal-Organic Nanoparticles with NETmix Reactor M.... more ABSTRACT Continuous Production of Magnetic and Metal-Organic Nanoparticles with NETmix Reactor M. Enis Leblebicia, Carlos M. Fontea, Marcelo F. Costaa, Filipe Ataídeb, M. Paz Garciac, Viviana Silvaa, Thomas Devicd, Patricia Horcajadad, Pedro Tavarese, João Pedro Araújoc, Rui Oliveirab, Joaquim L. Fariaa, Madalena M. Diasa, Jos Carlos B. Lopes*a aLaboratory of Separation and Reaction Engineering, Faculty of Engineering, University of Porto, Porto, Portugal bREQUIMTE/CQFB, Departamento de Química, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, Caparica, Portugal cIFIMUP/Departamento de Física, Universidade do Porto, Porto, Portugal dInstitut Lavoisier (CNRS 8180) Institut universitaire de France, Universit de Versailles, Versailles, France eCQVR, Departamento de Química, Universidade de Trás-os-Montes e Alto Douro, Vila Real, Portugal *e-mail: lopes@fe.up.pt More than half a century passed over the legendary lecture of Professor Richard Feynman, “There’s Plenty of Room at the Bottom” which is usually referred as the muse of nanotechnology. Today, nano-scale products find there way into a variety of promising services from more humane cancer treatments to increasing computer power/capacity, while their production scales are getting from laboratory towards industrial [1]. Chemical coprecipitation in batch stirred vessels has been a suitable, low-energy method to achieve nanometer scale crystals. However the focus now is not only to produce nanoparticles, but to control the particle size with a narrow particle size distribution (PSD). [2, 3]. Since coprecipitation in general results in wide PSD, high energy methods such as thermal decomposition, hydrothermal, and microwave synthesis were proposed and have been shown effective for size control of nanoparticles [2]. However, the productivity and scalability of these methods are lower than coprecipitation. Coprecipitation is done by vigorously mixing two or more reactant solutions, resulting in a product, which has low solubility in the medium. This supersaturated medium results in immediate nucleation [4] and particle growth. To produce uniform particles, it is crucial to keep a homogeneous concentration of the precursor molecules/clusters throughout the medium from the moment the reactant solutions contact until the end of the particle growth stage. Maintaining the homogeneity is the reason for the vigorous mixing in stirred vessels where batch coprecipitation takes place and it is the key factor on product quality, namely the PSD and on the energy input of the process. This work revisits coprecipitation method focusing on continuous production of magnetic nanoparticles (MNP) and metal – organic frameworks (MOFs) with high productivity without compromising PSD. The aim is to produce MNP and MOFs nanoparticles on a continuous reactor, namely the NETmix Reactor. The NETmix Reactor is a new technology consisting of a network of mixing chambers interconnected by transport channels [5]. Networks are generated by the repetition of unit cells where each unit cell consists of one chamber and two inlet and two outlet channels oriented at a 45º angle from the main flow direction. Above a critical channel Reynolds number, the system evolves to a self-sustained oscillatory laminar flow regime inside the mixing chambers inducing local strong laminar mixing. This network system of identical units, results in a flexible static mixer, which can be scaled-up easily without changing the design of mixing units. Magnetite synthesis with NETmix reactor was performed by mixing an aqueous solution of Fe2+ and Fe3+ salts with a base solution continuously to result in a pH value of 9.5 under inert atmosphere and 45°C. Trisodium citrate was used to stabilize particles. At this temperature and pressure, the solubility of magnetite is of order of 10-8 mol/kg the solubility of water [6]. This degree of supersaturation favors nucleation rather than particle growth therefore resulting in small crystals. Maturation time of 10 minutes was proven sufficient to ensure total conversion of iron salts to magnetite crystals. The washed crystals were characterized using dynamic light scattering, X-Ray diffraction, high-resolution transmission electron microscopy, Raman spectroscopy and supercooled quantum interference device. The pure magnetite crystals were found to be 4.8±0.25 nm, monocrystalline and superparamagnetic. The space-time yield of the process was 4.3 tons/m3/day. Two different iron-based metal-organic frameworks were also synthesized using the NETmix reactor namely iron fumarate MIL-88A [7] and iron trimesate MIL-100 [8]. An equilibrium model for iron (III) and the polycarboxylic acids was developed, in order to avoid formation of amourphous phases thus eliminating kinetic limitations. In this way, the nucleation of the MOFs is fast, which is further favored by the immediate homogenization provided by NETmix reactor which resulted in smaller and more uniform particles.…
ABSTRACT A PRESENTE INVENÇÃO REFERE-SE A NOVOS CATALISADORES HÍBRIDOS DE VANÁDIO DE FÓRMULA GERAL... more ABSTRACT A PRESENTE INVENÇÃO REFERE-SE A NOVOS CATALISADORES HÍBRIDOS DE VANÁDIO DE FÓRMULA GERAL I EM QUE:N=1 A 4;R1 E R2 SÃO INDEPENDENTES PODENDO SER DIFERENTES OU IGUAIS E PODEM SER -H, -X (HALOGÉNEO), C1 A C4 ALQUIL LINEAR OU RAMIFICADO, -NO2, -OH, -OME, -OET E; A É UM MATERIAL SUPORTE COM GRUPOS FUNCIONAIS OH NA SUA SUPERFÍCIE.A PRESENTE INVENÇÃO INCORPORA TAMBÉM A APLICAÇÃO DESTES COMPLEXOS EM PROCESSOS DE OXIDAÇÃO SELECTIVA DE CICLOALCANOS PARA PRODUZIR ÁLCOOIS E CETONAS CÍCLICAS. QUANDO APLICADOS NO PROCESSO DE OXIDAÇÃO, OS NOVOS CATALISADORES DE VANÁDIO PERMITEM UMA CONVERSÃO E SELECTIVIDADE ELEVADAS PARA OS PRODUTOS DE REACÇÃO CORRESPONDENTES, ATRAVÉS DO DIOXIGÉNIO (O2), OXIDANTE BARATO, DISPONÍVEL NO AR, SOB CONDIÇÕES DE REACÇÃO MODERADAS, QUER NA PRESENÇA OU NA AUSÊNCIA DE ÁCIDOS HETEROCÍCLICOS.
ABSTRACT Volatile organic compounds (VOC) are harmful environmental pollutants originated from st... more ABSTRACT Volatile organic compounds (VOC) are harmful environmental pollutants originated from stationary and mobile sources, such as painting, printing, petroleum refineries, fuel storage and motor vehicles. As some VOCs are dangerous to human health and to the environment, their emissions are regulated. Catalytic oxidation to CO2 and water is an environmentally friendly technology for VOC abatement. It requires low temperatures (around 250-500 °C) and causes less NOx formation, compared to conventional thermal oxidation, which requires high operation temperatures (650-1100 °C). Metal oxides can be used as heterogeneous catalysts for VOC oxidation. Commonly used catalysts include manganese, copper, nickeland iron oxides. It has been reported that although metal oxide based catalysts are less active than supported precious metals in oxidizing VOC streams, they are generally more resistant to poisoning phenomena. However, mixed oxides can show good activities in catalytic oxidation of VOCs, thus being good candidates for this application. In this work, single oxides of lanthanum and nickel were used. Mixed oxide samples of La-Ni-O synthesized by an evaporation method, with La-Ni ratios of 1:1 and 1:2 were also evaluated. Catalyst samples were characterised by N2 adsorption at -196 °C, temperature programmed reduction, scanning electron microscopy and X-ray diffraction. The materials were tested in the oxidation of ethyl acetate, a compound widely used as a solvent in printing operations, glues, nail polish removers, etc. It was found that the mixed oxide was much more active that the single oxide catalysts, allowing 100 % conversion of the VOC into CO2 at ~250 °C, with no formation of CO. Full conversion was not achieved by any of the single oxides, and CO was detected. The La:Ni 1:2 sample was more active than the 1:1 analogue. The 1:2 mixed oxide had a much larger surface area and also easier reducibility than the 1:1 sample. Both mixed oxides had larger surface area and higher reducibility than the single components, which can explain their improved performance.
A commercial iron oxide support is compared with Fe 2 O 3 samples prepared by decomposition of ir... more A commercial iron oxide support is compared with Fe 2 O 3 samples prepared by decomposition of iron nitrate, at 300 C and 500 C and heating times varying from 30 min to 96 h in N 2. Different methods were used for gold deposition, namely double impregnation ...
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