Marcela Fernandes - Academia.edu (original) (raw)

Papers by Marcela Fernandes

Anais do XXXVII Congresso Brasileiro de Sistemas Particulados, 2015

Colloids and Surfaces A: Physicochemical and Engineering Aspects, 2021

Abstract As a consequence of the inadequate disposal of pharmaceutical products and a residual po... more Abstract As a consequence of the inadequate disposal of pharmaceutical products and a residual portion that is not absorbed by the organism and is disposed into domestic sewage, antibiotics have been found in water resources. This results in serious problems for the environment and for human health, thus, efficient methods to remove these compounds from aqueous effluents are necessary. In this study, carbon with silver and copper oxide nanoparticles supported in activated carbon (CA-NPsAg/CuO), silver and copper oxide nanoparticles supported in graphene (OGR-NPsAg/CuO), and graphene oxide impregnated with silver and copper oxide nanoparticles supported in activated carbon (CA-OGR-NPsAg/CuO) to remove the cephalexin antibiotic in aqueous solution was investigated. These adsorbents were characterized through scanning electron microscopy and zeta potential. Adsorption equilibrium data were obtained for those three adsorbents at pH 6.7 (natural) and temperature 25 ∘C and the isotherm models of Langmuir, Freundlich, Sips, Sigmoidal Langmuir, and Dubin-Astakov were investigated to describe the data. Langmuir model was the one that better described the experimental equilibrium data for the adsorbent CA-OGR-NPsAg/CuO, while for the adsorbent CA-NPsAg/CuO, it was the Sips model, and Freundlich model for the adsorbent OGR-NPsAg/CuO. At low cephalexin concentration levels, the better performance regarding removal capacity was the adsorbent CA-NPsAg/CuO.The maximum adsorption capacity of each adsorbent was 756.8 mg g−1, 557.7 mg g−1, and 95.82 mg g−1 for CA-OGR-NPsAg/CuO, CA-NPsAg/CuO, and OGR-NPsAg/CuO, respectively. The knowledge about those studied adsorbents can improve the treatment of water contaminated with cephalexin antibiotic.

Environmental Science and Pollution Research, 2019

The present study proposes the synthesis and characterization of graphene oxide (GO) and its appl... more The present study proposes the synthesis and characterization of graphene oxide (GO) and its application in the adsorption of the antibiotic cephalexin (CFX) in aqueous solution. The characterization of graphene oxide was obtained by scanning electron microscopy (SEM), transmission electron microscopy (TEM), and zeta potential. The influence of pH on the batch adsorption process was investigated by analysing adsorption equilibrium isotherms and adsorption kinetics. The images obtained by SEM and TEM presented the typical morphology attributed to GO sheets. The kinetic adsorption tests showed that equilibrium was reached in 420 min, and an adsorption capacity of 164 mg g −1 was obtained. The models that best fit the experimental data were pseudo-second as well as the Langmuir isotherm. Therefore, GO was effective for removing the CFX antibiotic from aqueous solution by using a batch adsorption process.

Materials Research, 2018

Inorganic nanoparticles incorporation in polymer membranes for filtration processes has attracted... more Inorganic nanoparticles incorporation in polymer membranes for filtration processes has attracted the attention of researchers in order to improve in some ways their performance. In this work, AgNPs were synthesized "in situ" in cellulose acetate (CA) membrane by chemical reduction of a silver salt. The membranes were prepared by the nonsolvent induced phase inversion method. Asymmetric membranes without (CA-M) and with adsorbed AgNPs (CA-Ag-M) were obtained. Ultrafiltration properties were confirmed for both membranes (16 nm of average pore diameter) and average crystallite size of 21 nm for the adsorbed AgNPs was computed. Contact angle measured with Milli-Q water and dry CA-Ag-M is near zero while for the CA-M is around 80º. The CA-M showed water permeability of 214 Lh-1 m-2 , while the CA-Ag-M permeability was 1651 Lh-1 m-2 .

Materials Research, 2017

In this article was developed a green synthesis of CuO nanoparticles on vegetal activated carbon ... more In this article was developed a green synthesis of CuO nanoparticles on vegetal activated carbon (VAC), using pomegranate leaf extract as reducing and stabilizing agent in the removal of multiple pollutants. The impregnated carbons with CuO nanoparticles were characterized morphologically and structurally. The SEM and XRD analysis, after carbons modification, showed that the surface structure remained porous with CuO nanoparticles sizes between 40 and 78 nm. As concern to the contaminants atrazine, caffeine and diclofenac, it is observed that the maximum adsorption capacities practically did not suffer interference by the presence of 1.5% Cu nanoparticles, keeping their values very close to those obtained with pure carbon. The nitrate removal was favored by the impregnation of CuO nanoparticles, from 0.93 mg g-1 to 4.09 mg g-1. The results are promising and demonstrate that it is possible to obtain VAC impregnated whit nanoparticles of CuO by a non-polluting and low cost method.

Journal of Nanomaterials, 2017

Fe2O3 nanoparticles (as maghemite and hematite mixtures) were prepared using adapted sol-gel meth... more Fe2O3 nanoparticles (as maghemite and hematite mixtures) were prepared using adapted sol-gel method from a polyvinylpyrrolidone (PVP) aqueous solution in various Fe3+ : PVP monomer ratios. Analysis of X-ray diffraction was obtained to evaluate the crystalline state, average crystallite size, and composition of iron oxide phases. The morphology and average nanoparticles size were evaluated by electronic transmission microscopy. Magnetic properties of iron oxide were analyzed at low and room temperatures. Optical characteristics were evaluated by UV-Vis photoacoustic spectroscopy and the Mössbauer spectrum was obtained in order to evaluate subtle changes in the nuclear environment of the iron atoms.

Environmental Technology, 2017

In this work, we synthesized iron-oxide nanoparticles (NPsFeO) via a green synthesis method, usin... more In this work, we synthesized iron-oxide nanoparticles (NPsFeO) via a green synthesis method, using Moringa oleifera leaf extract, and evaluated its fluoride ion adsorption potential, comparing its efficiency with a commercially available adsorbent (activated carbon of bone [BGAC]). The adsorbent materials were characterized using X-ray diffraction, transmission, and scanning electronic microscopy, X-ray dispersive energy spectrometry, and N2 adsorption/desorption. The results showed that the maximum adsorption occurred in pH 7 for NPsFeO and pH 5 for the BGAC. Adsorption kinetic tests showed that the equilibrium was reached in 40 min for the NPsFeO, and 90 min for BGAC, with adsorption potential of 1.40 and 1.20 mg g, respectively. The model that best described the kinetic data was pseudo-first-order for NPsFeO and pseudo-second-order for BGAC. The Langmuir isotherm had a better fit for both adsorbents. The thermodynamic parameters indicated spontaneous and endothermic adsorption at 30°C, 40°C, and 50°C for BGAC, and at 30°C for NPsFeO. The regeneration process showed that it is possible to reuse NPsFeO three times in the fluoride ion adsorption process. As a result of its adsorption capabilities and the shortest contact time to achieve equilibrium, the NPsFeO is a highly promising material for fluoride ion removal.

Materials Letters, 2017

This work describes the synthesis of ferrite nanoparticles and the zinc and cobalt doping effect ... more This work describes the synthesis of ferrite nanoparticles and the zinc and cobalt doping effect on tuning their magnetic properties. The zinc doping led to formation of a secondary crystalline phase (ZnO), which meant that the Zn and Co individual ions show different physical-chemical affinities for the two types of lattice sites. Zerofield cooling and field cooling curves were elaborated to study the magnetization unblocking process of these nanoparticles. The metal doping effect led to large differences in the magnetization curves. The zinc-doped samples were shown to exhibit classical magnetization unblocking, being superparamagnetic below the room temperature. The cobalt doping increased the blocking temperature to above room temperature. The amount of cobalt did not change the coercive field of the doped samples. The coercive field of zinc-doped samples followed the same trend, but with a much lower value (0.6 kOe) when compared with cobalt-doped samples (18 kOe), showing a great change in magnetic anisotropy. The current synthesis approach offered a facile way to synthesize ferrite nanoparticles with metal doping-tunable magnetic properties by an environmentally friendly and facile sol-gel approach using water as solvent. This finding motivated us to think these ferrite nanoparticles can be attractive for biomedical and/or technological applications, although further studies other than these are still required.

Environmental Technology, 2016

Continuous flow experiments (450 mL min(-1)) were performed in household filter in order to inves... more Continuous flow experiments (450 mL min(-1)) were performed in household filter in order to investigate the removal and/or inactivation of T4 bacteriophage, using granular activated carbon (GAC) modified with silver and/or copper oxide nanoparticles at different concentrations. GAC and modified GAC were characterized by X-ray diffractometry, specific surface area, pore size and volume, pore average diameter, scanning electron microscopy, transmission electron microscopy, zeta potential and atomic absorption spectroscopy. The antiviral activity of the produced porous media was evaluated by passing suspensions of T4 bacteriophage (∼10(5) UFP/mL) through filters. The filtered water was analyzed for the presence of the bacteriophage and the release of silver and copper oxide. The porous media containing silver and copper oxide nanoparticles showed high inactivation capacity, even reaching reductions higher than 3 log. GAC6 (GAC/Ag0.5%Cu1.0%) was effective in the bacteriophage inactivation, reaching 5.53 log reduction. The levels of silver and copper released in filtered water were below the recommended limits (100 ppb for silver and 1000 ppb for copper) in drinking water. From this study, it is possible to conclude that activated carbon modified with silver and copper oxide nanoparticles can be used as a filter for virus removal in the treatment of drinking water.

Asian Pacific Journal of Cancer Prevention, 2014

It is becoming progressively more understandable that different phytochemicals isolated from edib... more It is becoming progressively more understandable that different phytochemicals isolated from edible plants interfere with specific stages of carcinogenesis. Cancer cells have evolved hallmark mechanisms to escape from death. Concordant with this approach, there is a disruption of spatiotemproal behaviour of signaling cascades in cancer cells, which can escape from apoptosis because of downregulation of tumor suppressor genes and overexpression of oncogenes. Genomic instability, intra-tumor heterogeneity, cellular plasticity and metastasizing potential of cancer cells all are related to molecular alterations. Data obtained through in vitro studies has convincingly revealed that curcumin, EGCG, resveratrol and quercetin are promising anticancer agents. Their efficacy has been tested in tumor xenografted mice and considerable experimental findings have stimulated researchers to further improve the bioavailability of these nutraceuticals. We partition this review into different sections with emphasis on how bioavailability of curcumin, EGCG, resveratrol and quercetin has improved using different nanotechnology approaches.

The Canadian Journal of Chemical Engineering, 2016

Water treatment plants are designed to remove turbidity and apparent colour, and produce safe wat... more Water treatment plants are designed to remove turbidity and apparent colour, and produce safe water from a microbiological and chemical point of view. Disinfection is the step responsible for the microbiological security, for which chlorine is the most widely-used agent, since it can react with organic matter present in raw water to form total trihalomethanes (TTHM), which are harmful to humans. In this context, it is proposed to evaluate the effectiveness of the combined process of coagulation, flocculation, and sedimentation (C/F/S) followed by an activated carbon column. The water for the tests was from the Pirap o River (Brazil) with low colour and turbidity. In C/F/S tests, natural coagulant solutions from Moringa oleifera (MO) degreased with ethanol (MO(et)) and hexane (MO(hex)) were compared to coagulant aluminum polychloride (PAC) with further filtration in an activated carbon column. For all these tests, removal efficiency of apparent colour, turbidity, dissolved organic carbon (DOC), and compounds with UV 254nm absorption (UV 254nm) were evaluated. The disinfection process was performed and residual chlorine and TTHM formation were evaluated. It was observed that the process of C/F/S using MO(et) followed by filtration through activated carbon was able to reduce the values of physicochemical parameters (96 % removal for turbidity and apparent colour, 93 % for UV 254nm , and 99 % for DOC) with reduced formation of TTHM (25.31 mg/L). Moreover, oil extraction with ethanol presents advantages over hexane due to being a solvent with good operational security, low toxicity, and being a bio-renewable source, all characteristics not present in hexane.

Aguas Subterrâneas, Feb 19, 2015

Environmental Technology, 2015

This study aimed to evaluate the efficiency of the coagulation/flocculation/dissolved air flotati... more This study aimed to evaluate the efficiency of the coagulation/flocculation/dissolved air flotation (C/F/DAF) process using the coagulant Moringa oleifera (MO) seed powder, and to analyze the profile of fatty acids present in the generated sludge after treatment. For the tests, deionized water artificially contaminated with cell cultures of Anabaena flos-aquae was used, with a cell density on the order of 10(4) cells.mL(-1). C/F/DAF tests were conducted using "Flotest" equipment. For fatty acid profile analyses, a gas chromatograph equipped with a flame ionization detector was used. It was seen that the optimal dosage (100 mg.L(-1)) of MO used in the C/F/DAF process was efficient at removing nearly all A. flos-aquae cells (96.4%). The sludge obtained after treatment contained oleic acid (61.7%) and palmitic acid (10.8%). Thus, a water treatment process using C/F/DAF linked to integral MO powder seed was found to be efficient in removing cells of cyanobacteria, and produced a sludge rich in oleic acid that is a precursor favorable for obtaining quality biodiesel, thus becoming an alternative application for the recycling of such biomass.

Anais do XXXVII Congresso Brasileiro de Sistemas Particulados, 2015

Matéria (Rio de Janeiro), 2014

Iron oxide nanoparticles (ION) have been studied for essential applications, like detection of bi... more Iron oxide nanoparticles (ION) have been studied for essential applications, like detection of biological constituents (virus, bacterials, cell, nucleic acids, protein, enzyme, etc.), magnetic bioseparation and clinic therapy and diagnosis (such as MRI magnetic fluid and hyperthermia). In this work, γ-Fe 2 O 3 has been synthetized by a adapted sol-gel method and entraped in poly ε-caprolactone (PCL) nanocapsules. The superparamagnetic nanocapsules have been formulated by double emulsion evaporation method. Some variables affecting the polydispersity index, zeta potential surface and size of nanocapsules were studied aiming optimize the formulation process of maghemite-loaded PCL nanocapsules. The following parameters were selected: sonication time, PCL concentration in organic phase, PVA concentration in external aqueous phase and maghemite/PCL weight ratio. Under these experimental conditions, the resulting nanocapsules displayed a mean size of about 346 nm and a maghemite content of about 7.5 µg/mg of nanocapsules and superparamagnetic behaviour at room temperature.

Química Nova, 2014

New techniques for treating wastewater, particularly the removal or degradation of organic pollut... more New techniques for treating wastewater, particularly the removal or degradation of organic pollutants and heavy metals, among other pollutants, have been extensively studied. The use of nanostructured iron oxides as adsorbent and photocatalyst for the removal of these contaminants has proved a promising approach, not only because of their high treatment efficiency, but also for their cost-effectiveness, having the flexibility for in situ and ex situ applications. In this review, we briefly introduced the most used kinds of iron oxide nanoparticles, some synthesis techniques for iron oxide nanostructure formation, their potential benefits in environmental clean-up, and their recent advances and applications in wastewater treatment. These advances range from the direct applications of synthesized nanoparticles as adsorbents for removing toxic contaminants or as catalysts to oxidize and break down noxious contaminants (including bacteria and viruses) in wastewater, to integrating nanoparticles into conventional treatment technologies, such as composite photocatalytic filters (membranes, sand and ceramic) that combine separation technology with photocatalytic activity. Finally, the impact of nanoparticles on the environment and human health is briefly discussed.

European Journal of Pharmaceutical Sciences, 2013

Magnetic nanoparticles have been proposed as interesting tools for biomedical purposes. One of th... more Magnetic nanoparticles have been proposed as interesting tools for biomedical purposes. One of their promising utilization is the MRI in which magnetic substances like maghemite are used in a nanometric size and encapsulated within locally biodegradable nanoparticles. In this work, maghemite has been obtained by a modified sol-gel method and encapsulated in polymer-based nanospheres. The nanospheres have been prepared by single emulsion evaporation method. The different parameters influencing the size, polydispersity index and zeta potential surface of nanospheres were investigated. The size of nanospheres was found to increase as the concentration of PLGA increases, but lower sizes were obtained for 3 min of sonication time and surfactant concentration of 1%. Zeta potential response of magnetic nanospheres towards pH variation was similar to that of maghemite-free nanospheres confirming the encapsulation of maghemite within PLGA nanospheres. The maghemite entrapment efficiency and maghemite content for nanospheres are 12% and 0.59% w/w respectively.

Materials Research, 2015

Poly(glycolide-co-lactide) (PLGA) nanospheres containing magnetic materials have been extensively... more Poly(glycolide-co-lactide) (PLGA) nanospheres containing magnetic materials have been extensively studied because of its biomedical applications. Therefore, it is very important to know thermal properties of these materials in addition to other physical properties. Thermal degradation activation energy (E α) of PLGA nanospheres with maghemite entrapment (PLGA-Mag), PLGA nanospheres (hollow spheres) (PLGA-H) obtained by an emulsion method and unprocessed PLGA (PLGA-R) were calculated by isoconversional Vyazovkin method based on data of TG analysis in order to evaluate modifications in thermal behavior caused by nanospheres obtainment process or by maghemite entrapment. Both hydrodynamic diameter in the range of 200-250 nm and polydispersity index lower than 0.3 are considered satisfactory. Thermal degradation of PLGA-R begins at higher temperatures than those of PLGA-H and PLGA-Mag, but processed samples presented increase in thermal stability, which was greater before processing by emulsion and in the presence of the magnetic materials. PLGA-Mag presents superparamagnetic behavior at room temperature.

Journal of Applied Physics, 2013

Fe 2 O 3 nanoparticles with sizes ranging from 15 to 53 nm were synthesized by a modified sol-gel... more Fe 2 O 3 nanoparticles with sizes ranging from 15 to 53 nm were synthesized by a modified sol-gel method. Maghemite particles as well as particles with admixture of maghemite and hematite were obtained and characterized by XRD, FTIR, UV-Vis photoacoustic and M€ ossbauer spectroscopy, TEM, and magnetic measurements. The size and hematite/maghemite ratio of the nanoparticles were controlled by changing the Fe:PVA (poly (vinyl alcohol)) monomeric unit ratio used in the medium reaction (1:6, 1:12, 1:18, and 1:24). The average size of the nanoparticles decreases, and the maghemite content increases with increasing PVA amount until 1:18 ratio. The maghemite and hematite nanoparticles showed cubic and hexagonal morphology, respectively. Direct band gap energy were 1.77 and 1.91 eV for A6 and A18 samples. Zero-field-cooling-field-cooling curves show that samples present superparamagnetic behavior. Maghemite-hematite phase transition and hematite N eel transition were observed near 700 K and 1015 K, respectively. Magnetization of the particles increases consistently with the increase in the amount of PVA used in the synthesis. M€ ossbauer spectra were adjusted with a hematite sextet and maghemite distribution for A6, A12, and A24 and with maghemite distribution for A18, in agreement with XRD results. V

The Canadian Journal of Chemical Engineering, 2016

The present research evaluates the groundwater nitrate concentration of the Maringa region (Paran... more The present research evaluates the groundwater nitrate concentration of the Maringa region (Parana State, Brazil) aiming at nitrate removal by coagulation/flocculation using a natural coagulant obtained from the seeds of the Moringa oleifera Lam. plant (MO) combined with an activated carbon filter. Groundwater samples were collected in Maringa City metropolitan area and characterized by physicochemical analyses. The results showed groundwater NO3− concentrations ranging from 0–60 mg NO3− L−1. Thus, the nitrate variation in the water used in the coagulation/flocculation assays lay between 10–60 mg · L−1 of NO3−. In these assays both aqueous and saline MO raw extracts were added (concentrations between 0.25–11 g · L−1). Coagulation/flocculation treatment with aqueous MO extract presents nitrate removal of 73.3 %, and saline MO extract presents 85.4 %. The source that presented the highest nitrate concentration along with the ideal MO concentration in the coagulation/flocculation process was used for the coagulation/flocculation process followed by activated carbon filtration. The treatment with MO combined with the filter met Brazilian, American, and international potability standards for nitrate and turbidity. The present study reveals the presence of nitrate in the groundwater of the area and also enables new procedures for treating this kind of water in small rural properties and needy communities.

Anais do XXXVII Congresso Brasileiro de Sistemas Particulados, 2015

Colloids and Surfaces A: Physicochemical and Engineering Aspects, 2021

Abstract As a consequence of the inadequate disposal of pharmaceutical products and a residual po... more Abstract As a consequence of the inadequate disposal of pharmaceutical products and a residual portion that is not absorbed by the organism and is disposed into domestic sewage, antibiotics have been found in water resources. This results in serious problems for the environment and for human health, thus, efficient methods to remove these compounds from aqueous effluents are necessary. In this study, carbon with silver and copper oxide nanoparticles supported in activated carbon (CA-NPsAg/CuO), silver and copper oxide nanoparticles supported in graphene (OGR-NPsAg/CuO), and graphene oxide impregnated with silver and copper oxide nanoparticles supported in activated carbon (CA-OGR-NPsAg/CuO) to remove the cephalexin antibiotic in aqueous solution was investigated. These adsorbents were characterized through scanning electron microscopy and zeta potential. Adsorption equilibrium data were obtained for those three adsorbents at pH 6.7 (natural) and temperature 25 ∘C and the isotherm models of Langmuir, Freundlich, Sips, Sigmoidal Langmuir, and Dubin-Astakov were investigated to describe the data. Langmuir model was the one that better described the experimental equilibrium data for the adsorbent CA-OGR-NPsAg/CuO, while for the adsorbent CA-NPsAg/CuO, it was the Sips model, and Freundlich model for the adsorbent OGR-NPsAg/CuO. At low cephalexin concentration levels, the better performance regarding removal capacity was the adsorbent CA-NPsAg/CuO.The maximum adsorption capacity of each adsorbent was 756.8 mg g−1, 557.7 mg g−1, and 95.82 mg g−1 for CA-OGR-NPsAg/CuO, CA-NPsAg/CuO, and OGR-NPsAg/CuO, respectively. The knowledge about those studied adsorbents can improve the treatment of water contaminated with cephalexin antibiotic.

Environmental Science and Pollution Research, 2019

The present study proposes the synthesis and characterization of graphene oxide (GO) and its appl... more The present study proposes the synthesis and characterization of graphene oxide (GO) and its application in the adsorption of the antibiotic cephalexin (CFX) in aqueous solution. The characterization of graphene oxide was obtained by scanning electron microscopy (SEM), transmission electron microscopy (TEM), and zeta potential. The influence of pH on the batch adsorption process was investigated by analysing adsorption equilibrium isotherms and adsorption kinetics. The images obtained by SEM and TEM presented the typical morphology attributed to GO sheets. The kinetic adsorption tests showed that equilibrium was reached in 420 min, and an adsorption capacity of 164 mg g −1 was obtained. The models that best fit the experimental data were pseudo-second as well as the Langmuir isotherm. Therefore, GO was effective for removing the CFX antibiotic from aqueous solution by using a batch adsorption process.

Materials Research, 2018

Inorganic nanoparticles incorporation in polymer membranes for filtration processes has attracted... more Inorganic nanoparticles incorporation in polymer membranes for filtration processes has attracted the attention of researchers in order to improve in some ways their performance. In this work, AgNPs were synthesized "in situ" in cellulose acetate (CA) membrane by chemical reduction of a silver salt. The membranes were prepared by the nonsolvent induced phase inversion method. Asymmetric membranes without (CA-M) and with adsorbed AgNPs (CA-Ag-M) were obtained. Ultrafiltration properties were confirmed for both membranes (16 nm of average pore diameter) and average crystallite size of 21 nm for the adsorbed AgNPs was computed. Contact angle measured with Milli-Q water and dry CA-Ag-M is near zero while for the CA-M is around 80º. The CA-M showed water permeability of 214 Lh-1 m-2 , while the CA-Ag-M permeability was 1651 Lh-1 m-2 .

Materials Research, 2017

In this article was developed a green synthesis of CuO nanoparticles on vegetal activated carbon ... more In this article was developed a green synthesis of CuO nanoparticles on vegetal activated carbon (VAC), using pomegranate leaf extract as reducing and stabilizing agent in the removal of multiple pollutants. The impregnated carbons with CuO nanoparticles were characterized morphologically and structurally. The SEM and XRD analysis, after carbons modification, showed that the surface structure remained porous with CuO nanoparticles sizes between 40 and 78 nm. As concern to the contaminants atrazine, caffeine and diclofenac, it is observed that the maximum adsorption capacities practically did not suffer interference by the presence of 1.5% Cu nanoparticles, keeping their values very close to those obtained with pure carbon. The nitrate removal was favored by the impregnation of CuO nanoparticles, from 0.93 mg g-1 to 4.09 mg g-1. The results are promising and demonstrate that it is possible to obtain VAC impregnated whit nanoparticles of CuO by a non-polluting and low cost method.

Journal of Nanomaterials, 2017

Fe2O3 nanoparticles (as maghemite and hematite mixtures) were prepared using adapted sol-gel meth... more Fe2O3 nanoparticles (as maghemite and hematite mixtures) were prepared using adapted sol-gel method from a polyvinylpyrrolidone (PVP) aqueous solution in various Fe3+ : PVP monomer ratios. Analysis of X-ray diffraction was obtained to evaluate the crystalline state, average crystallite size, and composition of iron oxide phases. The morphology and average nanoparticles size were evaluated by electronic transmission microscopy. Magnetic properties of iron oxide were analyzed at low and room temperatures. Optical characteristics were evaluated by UV-Vis photoacoustic spectroscopy and the Mössbauer spectrum was obtained in order to evaluate subtle changes in the nuclear environment of the iron atoms.

Environmental Technology, 2017

In this work, we synthesized iron-oxide nanoparticles (NPsFeO) via a green synthesis method, usin... more In this work, we synthesized iron-oxide nanoparticles (NPsFeO) via a green synthesis method, using Moringa oleifera leaf extract, and evaluated its fluoride ion adsorption potential, comparing its efficiency with a commercially available adsorbent (activated carbon of bone [BGAC]). The adsorbent materials were characterized using X-ray diffraction, transmission, and scanning electronic microscopy, X-ray dispersive energy spectrometry, and N2 adsorption/desorption. The results showed that the maximum adsorption occurred in pH 7 for NPsFeO and pH 5 for the BGAC. Adsorption kinetic tests showed that the equilibrium was reached in 40 min for the NPsFeO, and 90 min for BGAC, with adsorption potential of 1.40 and 1.20 mg g, respectively. The model that best described the kinetic data was pseudo-first-order for NPsFeO and pseudo-second-order for BGAC. The Langmuir isotherm had a better fit for both adsorbents. The thermodynamic parameters indicated spontaneous and endothermic adsorption at 30°C, 40°C, and 50°C for BGAC, and at 30°C for NPsFeO. The regeneration process showed that it is possible to reuse NPsFeO three times in the fluoride ion adsorption process. As a result of its adsorption capabilities and the shortest contact time to achieve equilibrium, the NPsFeO is a highly promising material for fluoride ion removal.

Materials Letters, 2017

This work describes the synthesis of ferrite nanoparticles and the zinc and cobalt doping effect ... more This work describes the synthesis of ferrite nanoparticles and the zinc and cobalt doping effect on tuning their magnetic properties. The zinc doping led to formation of a secondary crystalline phase (ZnO), which meant that the Zn and Co individual ions show different physical-chemical affinities for the two types of lattice sites. Zerofield cooling and field cooling curves were elaborated to study the magnetization unblocking process of these nanoparticles. The metal doping effect led to large differences in the magnetization curves. The zinc-doped samples were shown to exhibit classical magnetization unblocking, being superparamagnetic below the room temperature. The cobalt doping increased the blocking temperature to above room temperature. The amount of cobalt did not change the coercive field of the doped samples. The coercive field of zinc-doped samples followed the same trend, but with a much lower value (0.6 kOe) when compared with cobalt-doped samples (18 kOe), showing a great change in magnetic anisotropy. The current synthesis approach offered a facile way to synthesize ferrite nanoparticles with metal doping-tunable magnetic properties by an environmentally friendly and facile sol-gel approach using water as solvent. This finding motivated us to think these ferrite nanoparticles can be attractive for biomedical and/or technological applications, although further studies other than these are still required.

Environmental Technology, 2016

Continuous flow experiments (450 mL min(-1)) were performed in household filter in order to inves... more Continuous flow experiments (450 mL min(-1)) were performed in household filter in order to investigate the removal and/or inactivation of T4 bacteriophage, using granular activated carbon (GAC) modified with silver and/or copper oxide nanoparticles at different concentrations. GAC and modified GAC were characterized by X-ray diffractometry, specific surface area, pore size and volume, pore average diameter, scanning electron microscopy, transmission electron microscopy, zeta potential and atomic absorption spectroscopy. The antiviral activity of the produced porous media was evaluated by passing suspensions of T4 bacteriophage (∼10(5) UFP/mL) through filters. The filtered water was analyzed for the presence of the bacteriophage and the release of silver and copper oxide. The porous media containing silver and copper oxide nanoparticles showed high inactivation capacity, even reaching reductions higher than 3 log. GAC6 (GAC/Ag0.5%Cu1.0%) was effective in the bacteriophage inactivation, reaching 5.53 log reduction. The levels of silver and copper released in filtered water were below the recommended limits (100 ppb for silver and 1000 ppb for copper) in drinking water. From this study, it is possible to conclude that activated carbon modified with silver and copper oxide nanoparticles can be used as a filter for virus removal in the treatment of drinking water.

Asian Pacific Journal of Cancer Prevention, 2014

It is becoming progressively more understandable that different phytochemicals isolated from edib... more It is becoming progressively more understandable that different phytochemicals isolated from edible plants interfere with specific stages of carcinogenesis. Cancer cells have evolved hallmark mechanisms to escape from death. Concordant with this approach, there is a disruption of spatiotemproal behaviour of signaling cascades in cancer cells, which can escape from apoptosis because of downregulation of tumor suppressor genes and overexpression of oncogenes. Genomic instability, intra-tumor heterogeneity, cellular plasticity and metastasizing potential of cancer cells all are related to molecular alterations. Data obtained through in vitro studies has convincingly revealed that curcumin, EGCG, resveratrol and quercetin are promising anticancer agents. Their efficacy has been tested in tumor xenografted mice and considerable experimental findings have stimulated researchers to further improve the bioavailability of these nutraceuticals. We partition this review into different sections with emphasis on how bioavailability of curcumin, EGCG, resveratrol and quercetin has improved using different nanotechnology approaches.

The Canadian Journal of Chemical Engineering, 2016

Water treatment plants are designed to remove turbidity and apparent colour, and produce safe wat... more Water treatment plants are designed to remove turbidity and apparent colour, and produce safe water from a microbiological and chemical point of view. Disinfection is the step responsible for the microbiological security, for which chlorine is the most widely-used agent, since it can react with organic matter present in raw water to form total trihalomethanes (TTHM), which are harmful to humans. In this context, it is proposed to evaluate the effectiveness of the combined process of coagulation, flocculation, and sedimentation (C/F/S) followed by an activated carbon column. The water for the tests was from the Pirap o River (Brazil) with low colour and turbidity. In C/F/S tests, natural coagulant solutions from Moringa oleifera (MO) degreased with ethanol (MO(et)) and hexane (MO(hex)) were compared to coagulant aluminum polychloride (PAC) with further filtration in an activated carbon column. For all these tests, removal efficiency of apparent colour, turbidity, dissolved organic carbon (DOC), and compounds with UV 254nm absorption (UV 254nm) were evaluated. The disinfection process was performed and residual chlorine and TTHM formation were evaluated. It was observed that the process of C/F/S using MO(et) followed by filtration through activated carbon was able to reduce the values of physicochemical parameters (96 % removal for turbidity and apparent colour, 93 % for UV 254nm , and 99 % for DOC) with reduced formation of TTHM (25.31 mg/L). Moreover, oil extraction with ethanol presents advantages over hexane due to being a solvent with good operational security, low toxicity, and being a bio-renewable source, all characteristics not present in hexane.

Aguas Subterrâneas, Feb 19, 2015

Environmental Technology, 2015

This study aimed to evaluate the efficiency of the coagulation/flocculation/dissolved air flotati... more This study aimed to evaluate the efficiency of the coagulation/flocculation/dissolved air flotation (C/F/DAF) process using the coagulant Moringa oleifera (MO) seed powder, and to analyze the profile of fatty acids present in the generated sludge after treatment. For the tests, deionized water artificially contaminated with cell cultures of Anabaena flos-aquae was used, with a cell density on the order of 10(4) cells.mL(-1). C/F/DAF tests were conducted using "Flotest" equipment. For fatty acid profile analyses, a gas chromatograph equipped with a flame ionization detector was used. It was seen that the optimal dosage (100 mg.L(-1)) of MO used in the C/F/DAF process was efficient at removing nearly all A. flos-aquae cells (96.4%). The sludge obtained after treatment contained oleic acid (61.7%) and palmitic acid (10.8%). Thus, a water treatment process using C/F/DAF linked to integral MO powder seed was found to be efficient in removing cells of cyanobacteria, and produced a sludge rich in oleic acid that is a precursor favorable for obtaining quality biodiesel, thus becoming an alternative application for the recycling of such biomass.

Anais do XXXVII Congresso Brasileiro de Sistemas Particulados, 2015

Matéria (Rio de Janeiro), 2014

Iron oxide nanoparticles (ION) have been studied for essential applications, like detection of bi... more Iron oxide nanoparticles (ION) have been studied for essential applications, like detection of biological constituents (virus, bacterials, cell, nucleic acids, protein, enzyme, etc.), magnetic bioseparation and clinic therapy and diagnosis (such as MRI magnetic fluid and hyperthermia). In this work, γ-Fe 2 O 3 has been synthetized by a adapted sol-gel method and entraped in poly ε-caprolactone (PCL) nanocapsules. The superparamagnetic nanocapsules have been formulated by double emulsion evaporation method. Some variables affecting the polydispersity index, zeta potential surface and size of nanocapsules were studied aiming optimize the formulation process of maghemite-loaded PCL nanocapsules. The following parameters were selected: sonication time, PCL concentration in organic phase, PVA concentration in external aqueous phase and maghemite/PCL weight ratio. Under these experimental conditions, the resulting nanocapsules displayed a mean size of about 346 nm and a maghemite content of about 7.5 µg/mg of nanocapsules and superparamagnetic behaviour at room temperature.

Química Nova, 2014

New techniques for treating wastewater, particularly the removal or degradation of organic pollut... more New techniques for treating wastewater, particularly the removal or degradation of organic pollutants and heavy metals, among other pollutants, have been extensively studied. The use of nanostructured iron oxides as adsorbent and photocatalyst for the removal of these contaminants has proved a promising approach, not only because of their high treatment efficiency, but also for their cost-effectiveness, having the flexibility for in situ and ex situ applications. In this review, we briefly introduced the most used kinds of iron oxide nanoparticles, some synthesis techniques for iron oxide nanostructure formation, their potential benefits in environmental clean-up, and their recent advances and applications in wastewater treatment. These advances range from the direct applications of synthesized nanoparticles as adsorbents for removing toxic contaminants or as catalysts to oxidize and break down noxious contaminants (including bacteria and viruses) in wastewater, to integrating nanoparticles into conventional treatment technologies, such as composite photocatalytic filters (membranes, sand and ceramic) that combine separation technology with photocatalytic activity. Finally, the impact of nanoparticles on the environment and human health is briefly discussed.

European Journal of Pharmaceutical Sciences, 2013

Magnetic nanoparticles have been proposed as interesting tools for biomedical purposes. One of th... more Magnetic nanoparticles have been proposed as interesting tools for biomedical purposes. One of their promising utilization is the MRI in which magnetic substances like maghemite are used in a nanometric size and encapsulated within locally biodegradable nanoparticles. In this work, maghemite has been obtained by a modified sol-gel method and encapsulated in polymer-based nanospheres. The nanospheres have been prepared by single emulsion evaporation method. The different parameters influencing the size, polydispersity index and zeta potential surface of nanospheres were investigated. The size of nanospheres was found to increase as the concentration of PLGA increases, but lower sizes were obtained for 3 min of sonication time and surfactant concentration of 1%. Zeta potential response of magnetic nanospheres towards pH variation was similar to that of maghemite-free nanospheres confirming the encapsulation of maghemite within PLGA nanospheres. The maghemite entrapment efficiency and maghemite content for nanospheres are 12% and 0.59% w/w respectively.

Materials Research, 2015

Poly(glycolide-co-lactide) (PLGA) nanospheres containing magnetic materials have been extensively... more Poly(glycolide-co-lactide) (PLGA) nanospheres containing magnetic materials have been extensively studied because of its biomedical applications. Therefore, it is very important to know thermal properties of these materials in addition to other physical properties. Thermal degradation activation energy (E α) of PLGA nanospheres with maghemite entrapment (PLGA-Mag), PLGA nanospheres (hollow spheres) (PLGA-H) obtained by an emulsion method and unprocessed PLGA (PLGA-R) were calculated by isoconversional Vyazovkin method based on data of TG analysis in order to evaluate modifications in thermal behavior caused by nanospheres obtainment process or by maghemite entrapment. Both hydrodynamic diameter in the range of 200-250 nm and polydispersity index lower than 0.3 are considered satisfactory. Thermal degradation of PLGA-R begins at higher temperatures than those of PLGA-H and PLGA-Mag, but processed samples presented increase in thermal stability, which was greater before processing by emulsion and in the presence of the magnetic materials. PLGA-Mag presents superparamagnetic behavior at room temperature.

Journal of Applied Physics, 2013

Fe 2 O 3 nanoparticles with sizes ranging from 15 to 53 nm were synthesized by a modified sol-gel... more Fe 2 O 3 nanoparticles with sizes ranging from 15 to 53 nm were synthesized by a modified sol-gel method. Maghemite particles as well as particles with admixture of maghemite and hematite were obtained and characterized by XRD, FTIR, UV-Vis photoacoustic and M€ ossbauer spectroscopy, TEM, and magnetic measurements. The size and hematite/maghemite ratio of the nanoparticles were controlled by changing the Fe:PVA (poly (vinyl alcohol)) monomeric unit ratio used in the medium reaction (1:6, 1:12, 1:18, and 1:24). The average size of the nanoparticles decreases, and the maghemite content increases with increasing PVA amount until 1:18 ratio. The maghemite and hematite nanoparticles showed cubic and hexagonal morphology, respectively. Direct band gap energy were 1.77 and 1.91 eV for A6 and A18 samples. Zero-field-cooling-field-cooling curves show that samples present superparamagnetic behavior. Maghemite-hematite phase transition and hematite N eel transition were observed near 700 K and 1015 K, respectively. Magnetization of the particles increases consistently with the increase in the amount of PVA used in the synthesis. M€ ossbauer spectra were adjusted with a hematite sextet and maghemite distribution for A6, A12, and A24 and with maghemite distribution for A18, in agreement with XRD results. V

The Canadian Journal of Chemical Engineering, 2016

The present research evaluates the groundwater nitrate concentration of the Maringa region (Paran... more The present research evaluates the groundwater nitrate concentration of the Maringa region (Parana State, Brazil) aiming at nitrate removal by coagulation/flocculation using a natural coagulant obtained from the seeds of the Moringa oleifera Lam. plant (MO) combined with an activated carbon filter. Groundwater samples were collected in Maringa City metropolitan area and characterized by physicochemical analyses. The results showed groundwater NO3− concentrations ranging from 0–60 mg NO3− L−1. Thus, the nitrate variation in the water used in the coagulation/flocculation assays lay between 10–60 mg · L−1 of NO3−. In these assays both aqueous and saline MO raw extracts were added (concentrations between 0.25–11 g · L−1). Coagulation/flocculation treatment with aqueous MO extract presents nitrate removal of 73.3 %, and saline MO extract presents 85.4 %. The source that presented the highest nitrate concentration along with the ideal MO concentration in the coagulation/flocculation process was used for the coagulation/flocculation process followed by activated carbon filtration. The treatment with MO combined with the filter met Brazilian, American, and international potability standards for nitrate and turbidity. The present study reveals the presence of nitrate in the groundwater of the area and also enables new procedures for treating this kind of water in small rural properties and needy communities.