Chemical Engineering Journal (CEJ)- Elsevier, 2024
Peroxymonosulfate (HSO5–) and persulfate (S2O82–), both sources of sulfate radicals (SO4*–), were... more Peroxymonosulfate (HSO5–) and persulfate (S2O82–), both sources of sulfate radicals (SO4*–), were evaluated for the first time in modified solar photo-Fenton using Fe-chelating agents (nitriloacetic acid (NTA), ethylene diaminetetraacetic acid (EDTA), ethylenediamine-N,Ń-disuccinic acid (EDDS) and citrate (Cit)) in comparison with hydrogen peroxide (H2O2) to degrade benzophenone-3 (BP-3), fipronil (FIP) and propylparaben (PPB) (100 µg L–1 each) in municipal tertiary effluent. Increasing HSO5– concentrations from 1.5 to 5.9 mmol L–1 reached ≥ 96 % removal for all iron complexes, while treatment efficiencies for all tested S2O82– concentrations (1.5–5.9 mmol L–1) were limited to 20 % to 55 %. This difference can be attributed to a pH decrease in the HSO5– system. The influence of pH and matrix composition upon treatment performance were also assessed in the FeNTA/S2O82– system, which was more efficient at pH < 7.0 due to higher availability of soluble iron, and partial removal of bicarbonate and humic acids caused by acidification. Matrix composition significantly influenced the process as higher degradation rates were achieved after isolated or combined removals of chloride, bicarbonate and sulfate. The comparison between naproxen (a high electron density compound) degradation and that of BP-3, FIP, and PPB by SO4*– - based advanced oxidation processes (SR-AOPs) was used to evaluate the influence of target compound structures upon treatment performance. S2O82− and HSO5– were ineffective for treatment at pH 7.0. Thus, H2O2 was the best peroxide source for target compounds degradation at neutral pH as this is the natural pH of municipal tertiary effluent and results indicated that the assessment and choice for SR-AOPs should consider the chemical structure of target compounds.
INTERNATIONAL JOURNAL OF ADVANCES IN MEDICAL BIOTECHNOLOGY, 2021
Hydroxyapatite [Ca 10 (PO 4) 6 (OH) 2 ] (HAp) represents an outstanding source for the developmen... more Hydroxyapatite [Ca 10 (PO 4) 6 (OH) 2 ] (HAp) represents an outstanding source for the development of materials with biomedical interest. This material is a part of the mineral phase of bones and teeth of animals and humans. Due to its osteointegrity, biocompatibility, and bioactivity, this material is considered one of the most promising materials for biomedical applications. Hydroxyapatite nanoparticles are synthesized mainly by traditional wet chemical precipitation, that uses non-environmentally friendly templates. In the last years, many attempts were directed to turn the hydroxyapatite nanoparticles synthesis greener, by application of the green synthesis approach. Recently, special attention has been given to the application of plant extracts as substitutes for synthetic templates. Therefore, this work aims to provide a general state of the art on the green synthesis of hydroxyapatite nanoparticles for biomedical application. Additionally, the main gaps regarding the green synthesis are carefully stated.
This work evaluated the simultaneous effect of the nanosilica-NPS:polycaprolactone-PCL ratio and ... more This work evaluated the simultaneous effect of the nanosilica-NPS:polycaprolactone-PCL ratio and the heat treatment on the wettability of the NPS/PCL coatings for application in aqueous systems. Silica nanoparticles were synthesized via the sol-gel route using silica precursors. The polycaprolactone (PCL) were coated by Silica nanoparticles in a solution using different concentrations of silica nanoparticles. The NPS/PCL coatings were characterized by field emission gun scanning electron microscopy (FEG/SEM), energy-dispersive X-ray spectroscopy (EDX), transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) and water contact angle (WCA). The results showed that water contact angle (WCA) decreased with the increment of the nanosilica achieving the maximum value of 67.60° ± 0.82 for the coating with the highest nano-silica particles (NPS-300). In addition, WCA values increase significantly after the heat treatment for the samples submitted to the highest NPS:PCL ratios (NPS-150T and NPS-300T), achieving a maximum value of 101.70° ± 0.94. These results are associated with the microstructural, thermal, and functional groups modifications showed by characterizations techniques In summary, this work provides new insights on wettability of hydrophobic materials nanoparticles that can be dispersed in aqueous systems.
Highly fluorescent nitrogen-doped carbon dots (CDs) were synthesized from cambuci juice (Campoman... more Highly fluorescent nitrogen-doped carbon dots (CDs) were synthesized from cambuci juice (Campomanesia phaea (O. Berg) Landrum) and successfully used for zinc (Zn2+) sensing based on fluorescence quenching. The CDs were synthesized at different pH, using NaOH and NH4OH as pH adjusters. The CDs synthesized were characterized by Transmission Electron Microscopy (TEM), X-Ray Diffraction (XRD), Raman spectroscopy, Fourier Transform Infrared Spectroscopy (FTIR), Zeta potential, UV–Vis, and fluorescence spectroscopy. The CDs synthesized from juice with pH 7 and adjusted by NH4OH presented a high sensitivity to Zn2+ and a higher quantum yield (21.26%). The minimum limit of detection (LOD) was 5.4 µм. The linear range (LR) is between 25 and 125 µм. The sensor exhibits great potential for applications as a zinc detector for biological and environmental systems.
Nano hydroxyapatite (nHA) was synthesized from different methods. Spherical-like shaped nanoparti... more Nano hydroxyapatite (nHA) was synthesized from different methods. Spherical-like shaped nanoparticles of nHA were synthesized by chemical precipitation using Euclea Natalensis root extract as a template for the first time. In addition, traditional synthesis was performed, obtaining rod-like nanoparticles. The formation of nHA was confirmed using Fourier Transform Infrared (FTIR), X-Ray Diffraction (XRD), and Transmission Electron Microscopy (TEM). HA from green route presented a spherical-like shape with smooth surface. However, nanogrooves covered over the surface of nHA obtained without green template. Additionally, the cytotoxic effect of the nHA nanoparticles on L929 viability was assessed using MTS assay. The particles exhibited less cellular toxicity at shorter incubation periods. Spherical-like and rod-like nHA particles interact differently with fibroblast after 24 h of evaluation.
Chemistry is a basic science and it is present in most aspects of daily life. For being an instru... more Chemistry is a basic science and it is present in most aspects of daily life. For being an instrument of human formation, assume a special role that expands cultural horizons and autonomy in the exercise of citizenship. Therefore, it is important that this subject is taught from an everyday life perspective so that it fulfills its transforming role. One of the problems that most developing countries face in science, technology, engineering, and mathematics (STEM) education is the lack of conventional materials and reagents for practical classes and demonstrations. Therefore, the present work aimed to build a breathalyzer simulator to be applied in a teaching class of chemistry. Several steps were followed since the construction of the breathalyzer, tests of its functionality using local alcoholic drinks as a source of ethanol and finally strategies were proposed for its application in the classroom. The results showed that the simulated breathalyzer was constructed using locally available materials, such as chalk, pen tubes and birthday balloons. Furthermore, during the device functional test was possible to observe color changes resulting from the interaction between the ethanol in the drinks and the acidic dichromate solution. Based on the results obtained, strategies were proposed for its usage in the classroom.
Journal of Environmental Chemical Engineering, 2020
The application of an ultra-high-molecular-weight polyethylene-based (UHMWPE) nanocomposite with ... more The application of an ultra-high-molecular-weight polyethylene-based (UHMWPE) nanocomposite with nanohydroxyapatite (HA) and organophilic bentonite (OB) for adsorption of tetracycline (TC) was evaluated. The nanocomposite was prepared by combining the high energy grinding and the muffle heat treatment. Their formulation was investigated through complete experimental design (23), varying amount of OB, temperature and sintering time. The morphology and structure of the UHMWPE/HA/OB (ultra-high-molecular-weight polyethylene-based, nanohydroxyapatite and organophilic bentonite) were characterized using Fourier transform infrared (FTIR) spectroscopy, Brunauer-Emmett-Teller (BET), Scanning Electron Microscopy (SEM) and Electron Microscopy Transmission (TEM). The adsorption of TC in the composite was investigated through batch and fixed-bed experiments. For the batch experiments, the UHMWPE/HA/OB nanocomposite adsorbed 8.72 mg∙g−1 TC at 328.15 K, at neutral pH and at 24 h of reaction. The experimental adsorption data for kinetics were best described by the pseudo second order model (R2 = 0.989) and the isotherms followed the Freundlich model (R2 = 0.996). The thermodynamic investigation indicated that the adsorption was an endothermic reaction and that there is an affinity between the adsorbent and the adsorbate. According to the results of the fixed-bed column experiment, the breakthrough curve was plotted and the characteristic column parameters were evaluated, and the experimental data were better described by the Yan model (R2 = 0.980). Based on the results of the work the UHMWPE/HA/OB nanocomposite is very promising for the removal of contaminants in aqueous medium.
Sodium montmorillonite organically modified by octadecylammonium (Np-Clay) and zinc oxide nanopar... more Sodium montmorillonite organically modified by octadecylammonium (Np-Clay) and zinc oxide nanoparticles (Np-ZnO) were incorporated into chitosan (C) matrix in different proportions to evaluate its mechanical properties and antimicrobial activities. The composites were obtained by polymer intercalation method in solution using acetic acid (1% v/v) as solvent. The functional groups, thermic behavior and surface morphology of the chitosan film and of the composites prepared with different percentages of Np-Clay and Np-ZnO were characterized through Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) and scanning electron microscopy (SEM). The results showed that a combined effect of clay and zinc oxide increases significantly the mechanical properties of pure chitosan. FTIR results confirmed good compatibility among functional groups of chitosan, montmorillonite/metallic oxides. The Np-ZnO distribution became more uniform in chitosan films when the Np-clay was incorporated, thus, the Np-Clay compatibilizes the Np-ZnO with the chitosan and the mechanical properties improved and without affecting the antimicrobial activity of the films. The thermal degradation temperature of the chitosan did not change significantly with the addition of Np-Clay, but changes significantly with Np-ZnO addition. In antimicrobial test was found that the chitosan and Np-ZnO showed a synergistic effect against to Escherichia coli and Staphylococcus aureus. The addition of Np-ZnO and C-Clay in chitosan resulted in enhancement of mechanical and antimicrobial properties, turning this material prospective for food packaging applications.
Colloids and Surfaces A: Physicochemical and Engineering Aspects, 2019
The development of nanomaterials has attracted increasing attention recently. The study of new te... more The development of nanomaterials has attracted increasing attention recently. The study of new technologies to obtain these materials becomes extremely important since the majority of the nanomaterials synthesized require reagents and solvents. These reagents and solvents are sometimes toxic and may generate harmful residues to the environment and the health of living beings. Therefore, green synthesis is a potential alternative to obtain nanoparticles, sustainably, using ecological sources. This study developed a method of synthesizing the green of zirconia (ZrO2) nanoparticles using Euclea natalensis (Natal gwarri or Natal ebony tree with African origin) plant extract. Moreover, the adsorptive properties against tetracycline were evaluated. A factorial design was applied in the synthesis process, and an optimization of the reaction parameters (plant extract concentration, precursor concentration, and calcination temperature) was also described for the first time in literature. The nanoparticles were characterized using the XRD, FTIR and TEM techniques, and then subjected to batch adsorption tests. The samples presented the zirconia monoclinic and tetragonal phases, according to the XRD analysis, yielding materials with minimum crystallite sizes equal to 5.25 nm. The FTIR spectra confirmed the results obtained by the XRD, presenting band characteristic of the zirconia monoclinic and tetragonal phases. The particles had a rounded morphology with a very low average diameter ranging from 5.90 to 8.54 nm. Moreover, the nanoparticles were applied to the adsorption of tetracycline. The samples were synthesized with vegetal extract and precursor concentration equal to 50 g L−1 and 0.03 mol L−1, respectively, and calcination temperature of 550 °C, presented in the best performance (loading of 30.45 mg g−1). The adsorption capacity of the zirconia synthesized in this study was significantly higher than other common materials applied to tetracycline removal. The green synthesis procedure, as well as the application of the zirconia nanoparticles to the adsorption of an emerging pollutant, were promising.
Journal of Inorganic and Organometallic Polymers and Materials, 2019
The goal of this paper was to synthesize and characterize core–shell iron-carbon nanoparticles. F... more The goal of this paper was to synthesize and characterize core–shell iron-carbon nanoparticles. For this purpose, nanoparticles were synthetized via a hydrothermal co-precipitation route, applying a 22 factorial experimental design with a central point, and varying both the concentration of the iron precursor (iron nitrate) and the reaction temperature. The nanoparticles were characterized via the following analysis: vibrating sample magnometry (VSM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), energy dispersive X-ray spectroscopy (EDX), high resolution field emission gun scanning electron microscopy (SEM/FEG) and transmission electron microscopy (TEM) analysis. The results showed that the hydrothermal co-precipitation synthesis route enabled the production of Fe3O4–Fe2O3@C core–shell nanoparticles with dimensions between 4 and 8 nm. An increase in iron nitrate concentration and temperature during synthesis entailed a decrease in the remnant field and the magnetization of the nanoparticles.
The low interaction between ultra high molecular weight polyethylene (UHMWPE) and hydroxyapatite ... more The low interaction between ultra high molecular weight polyethylene (UHMWPE) and hydroxyapatite (HA) has been one of the problems that results in a composite material with low mechanical and tribological performance due to the formation of agglomerates and microstructural defects. These properties affect the quality of the material when used for total joint implants and other applications in hard tissue engineering. This study investigated the effect of the addition of organophilic bentonite (BO) into the interface HA and UHMWPE. The composite was prepared by wet milling in a planetary mill and then by compression molding. The composites samples were characterized by XRD, FTIR, SEM and DSC. The tensile and tribological mechanical properties were also evaluated. Furthermore, in vitro degradation using simulated blood fluid (SBF) and hemocompatibility was performed. The results suggest that the addition of 10 wt% of organophilic bentonite improved the interface between the UHMWPE and HA by exfoliation/intercalation, presenting the best results of modulus of elasticity, tensile strength, coefficient of friction and rate of wear. The composite UHMWPE/HA/BO-10 wt% presented low water absorption and induced the growth of apatite crystals on its surface. Additionally, its hemocompatibility index is within normal limits and induced a low adhesion and agglomeration of platelets in contact with human blood, evidencing that the UHMWPE/HA/BO-10 wt% composite is promising for application in bone tissue engineering.
A nanocomposite composed of ultrahigh-molecular-weight polyethylene (UHMWPE) with organophilic be... more A nanocomposite composed of ultrahigh-molecular-weight polyethylene (UHMWPE) with organophilic bentonite (OB) and nanohydroxyapatite (HA) was prepared by combining high-energy mill grinding with muffle heat treatment. This material was then characterized using Fourier transform infrared (FTIR) spectroscopy and scanning electron microscopy (SEM). Moreover, the adsorption capacity of UHMWPE/HA/OB was evaluated using methylene blue (MB) dye as a model adsorbate. After 20 h, the nanocomposite removed 48.8 mg∙g-1 of MB. The results showed that this nanocomposite has a good adsorption capacity and can be effective in the removal of contaminants in aqueous media.
RESUMO – O azul de metileno (AM) é um corante orgânico-catiônico com diversas aplicações. Porém, ... more RESUMO – O azul de metileno (AM) é um corante orgânico-catiônico com diversas aplicações. Porém, o seu descarte sem o devido tratamento pode causar a poluição dos recursos hídricos. Diversas tecnologias têm sido estudadas para a remoção destes contaminantes das águas residuárias, destacando-se a adsorção, por ser um dos métodos mais eficazes e economicamente viáveis. Diante disso, estudou-se a remoção do corante AM em soluções aquosas aplicando um novo compósito de polietileno de ultra alto peso molecular (UHMWPE) com hidroxiapatita (HA) e bentonita organofílica (BO). Esse novo adsorvente foi obtido e caracterizado por Microscopia Eletrônica de Varredura (MEV). Para os ensaios de adsorção, mediu-se a concentração do corante no meio líquido por espectroscopia na região UV/visível. Os resultados experimentais mostraram que o compósito de UHMWPE/HA/BO possui propriedades favoráveis para utilização como adsorvente na remoção de AM, atingindo o percentual de remoção de 38% nas condições testadas.
With the increasing demand of biomaterials, numerous studies have been developed seeking to impro... more With the increasing demand of biomaterials, numerous studies have been developed seeking to improve its properties through new obtaining and manufacturing processes. This work aimed to aggregate antimicrobial property to a biocomposite constituted of a matrix of ultra-high molecular weight polyethylene (UHMWPEE) and hydroxyapatite, by the incorporation of zinc oxide nanoparticles. The samples were prepared based on a standard composition containing 95.0 wt% of UHMWPEE and 5.0 wt% of hydroxyapatite (blank). Three compositions were evaluated ranging the amount of zinc oxide nanoparticles incorporated in the standard sample. It was observed that the increase of zinc oxide concentration aggregate a good antibacterial property in the samples tested without cause significant changes in the mechanical properties of the composites.
Core-shell Fe 3 O 4 @C nanoparticles consist of a magnetic core and carbon coating, and exhibit h... more Core-shell Fe 3 O 4 @C nanoparticles consist of a magnetic core and carbon coating, and exhibit high adsorptive capacity, easy magnetic separation and reusability. Due to these properties, core–shell Fe 3 O 4 @C nanoparticles have great potential application in adsorption, separation and wastewater treatment. Magnetic separation based on the super paramagnetic Fe 3 O 4 has received considerable attention and is widely used for the removal of dye, oil pharmaceuticals and metals from water due to its high efficiency and economic viability. Therefore, the main characteristics of the core-shell Fe 3 O 4 @C nanoparticles, the different types of synthesis, as well as the main applications for the removal of water pollutants were reviewed. In this brief review, an overview of the basic properties of the Fe 3 O 4 @C core-shell nanoparticles are given, and the most important and more frequently used methods for the synthesis of Fe 3 O 4 @C core-shell nanoparticles have been summarized along with the description of its adsorbent application potential. Highlights • Magnetic core-shell Fe 3 O 4 @C nanoparticles combine excellent adsorptive capacity and easy magnetic separation. • Core-shell nanoparticles show high regeneration capability. • The use of magnetic core-shell Fe 3 O 4 @C nanoparticles provides over 90% removal of pollutants in aqueous media. • Magnetic core-shell Fe 3 O 4 @C nanoparticles regeneration has been manifesting great potential in water treatment.
Nowadays, the main application of coal mine in the world is to produce energy through thermoelect... more Nowadays, the main application of coal mine in the world is to produce energy through thermoelectric power plants. Energy generation is always associated with the production of enormous amounts of ashes, both bottom and fly ashes. The main objective of this work is to study the effect of time, temperate and concentration on Synthetic zeolites produced from utilizing minerals of coal bottom ash. However, for the factor significance analysis, factorial planning of two levels and three factors was used, where eight experiments were obtained, and the results of FTIR transmittance showed favorable variation in time and temperature, and the variation of the NaOH concentration was not significant. It was concluded that the concentration of NaOH only influences the zeolites formation when combined with the crystallization time.
In coal-burning processes combustion products has been the biggest problem for environmental pre... more In coal-burning processes combustion products has been the biggest problem for environmental prevention. This work aims at the use of bottom ashes, from the burning of mineral coal in thermal power plants, in the synthesis of zeolites. The motivation of this study was based on studies which show the presence of aluminosilicates in coal ash. Zeolites are aluminosilicates that exhibit crystalline structural arrangement and have high adsorption properties. The zeolite synthesis process has as its sole step the use of bottom ashes as alternative sources silica and aluminum. The zeolite materials obtained had a specific area of 771 m 2 /g, being attractive results due to the fact that the bottom ash has in its composition about 7.0% Fe, element that disadvantages the nucleation and formation of crystals process.
Transmission infrared spectroscopy (FTIR) was used to study the effect of the temperature and con... more Transmission infrared spectroscopy (FTIR) was used to study the effect of the temperature and concentration of octadecylamine (surfactant) in the conformation state of amine chains incorporated in a bentonite matrix by organophilization process. The temperature is the most important factor in conformational changes-gauche/trans. Whereas the simultaneous increase of the temperature and concentration of surfactant favors the disordered conformation-gauche. This result is very important in the development of organo-bentonite based polymeric nanocomposites because the intercalation of the polymer in the galleries of the organo-bentonite is dependent on the conformation of the alkyl chains.
Chemical Engineering Journal (CEJ)- Elsevier, 2024
Peroxymonosulfate (HSO5–) and persulfate (S2O82–), both sources of sulfate radicals (SO4*–), were... more Peroxymonosulfate (HSO5–) and persulfate (S2O82–), both sources of sulfate radicals (SO4*–), were evaluated for the first time in modified solar photo-Fenton using Fe-chelating agents (nitriloacetic acid (NTA), ethylene diaminetetraacetic acid (EDTA), ethylenediamine-N,Ń-disuccinic acid (EDDS) and citrate (Cit)) in comparison with hydrogen peroxide (H2O2) to degrade benzophenone-3 (BP-3), fipronil (FIP) and propylparaben (PPB) (100 µg L–1 each) in municipal tertiary effluent. Increasing HSO5– concentrations from 1.5 to 5.9 mmol L–1 reached ≥ 96 % removal for all iron complexes, while treatment efficiencies for all tested S2O82– concentrations (1.5–5.9 mmol L–1) were limited to 20 % to 55 %. This difference can be attributed to a pH decrease in the HSO5– system. The influence of pH and matrix composition upon treatment performance were also assessed in the FeNTA/S2O82– system, which was more efficient at pH < 7.0 due to higher availability of soluble iron, and partial removal of bicarbonate and humic acids caused by acidification. Matrix composition significantly influenced the process as higher degradation rates were achieved after isolated or combined removals of chloride, bicarbonate and sulfate. The comparison between naproxen (a high electron density compound) degradation and that of BP-3, FIP, and PPB by SO4*– - based advanced oxidation processes (SR-AOPs) was used to evaluate the influence of target compound structures upon treatment performance. S2O82− and HSO5– were ineffective for treatment at pH 7.0. Thus, H2O2 was the best peroxide source for target compounds degradation at neutral pH as this is the natural pH of municipal tertiary effluent and results indicated that the assessment and choice for SR-AOPs should consider the chemical structure of target compounds.
INTERNATIONAL JOURNAL OF ADVANCES IN MEDICAL BIOTECHNOLOGY, 2021
Hydroxyapatite [Ca 10 (PO 4) 6 (OH) 2 ] (HAp) represents an outstanding source for the developmen... more Hydroxyapatite [Ca 10 (PO 4) 6 (OH) 2 ] (HAp) represents an outstanding source for the development of materials with biomedical interest. This material is a part of the mineral phase of bones and teeth of animals and humans. Due to its osteointegrity, biocompatibility, and bioactivity, this material is considered one of the most promising materials for biomedical applications. Hydroxyapatite nanoparticles are synthesized mainly by traditional wet chemical precipitation, that uses non-environmentally friendly templates. In the last years, many attempts were directed to turn the hydroxyapatite nanoparticles synthesis greener, by application of the green synthesis approach. Recently, special attention has been given to the application of plant extracts as substitutes for synthetic templates. Therefore, this work aims to provide a general state of the art on the green synthesis of hydroxyapatite nanoparticles for biomedical application. Additionally, the main gaps regarding the green synthesis are carefully stated.
This work evaluated the simultaneous effect of the nanosilica-NPS:polycaprolactone-PCL ratio and ... more This work evaluated the simultaneous effect of the nanosilica-NPS:polycaprolactone-PCL ratio and the heat treatment on the wettability of the NPS/PCL coatings for application in aqueous systems. Silica nanoparticles were synthesized via the sol-gel route using silica precursors. The polycaprolactone (PCL) were coated by Silica nanoparticles in a solution using different concentrations of silica nanoparticles. The NPS/PCL coatings were characterized by field emission gun scanning electron microscopy (FEG/SEM), energy-dispersive X-ray spectroscopy (EDX), transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) and water contact angle (WCA). The results showed that water contact angle (WCA) decreased with the increment of the nanosilica achieving the maximum value of 67.60° ± 0.82 for the coating with the highest nano-silica particles (NPS-300). In addition, WCA values increase significantly after the heat treatment for the samples submitted to the highest NPS:PCL ratios (NPS-150T and NPS-300T), achieving a maximum value of 101.70° ± 0.94. These results are associated with the microstructural, thermal, and functional groups modifications showed by characterizations techniques In summary, this work provides new insights on wettability of hydrophobic materials nanoparticles that can be dispersed in aqueous systems.
Highly fluorescent nitrogen-doped carbon dots (CDs) were synthesized from cambuci juice (Campoman... more Highly fluorescent nitrogen-doped carbon dots (CDs) were synthesized from cambuci juice (Campomanesia phaea (O. Berg) Landrum) and successfully used for zinc (Zn2+) sensing based on fluorescence quenching. The CDs were synthesized at different pH, using NaOH and NH4OH as pH adjusters. The CDs synthesized were characterized by Transmission Electron Microscopy (TEM), X-Ray Diffraction (XRD), Raman spectroscopy, Fourier Transform Infrared Spectroscopy (FTIR), Zeta potential, UV–Vis, and fluorescence spectroscopy. The CDs synthesized from juice with pH 7 and adjusted by NH4OH presented a high sensitivity to Zn2+ and a higher quantum yield (21.26%). The minimum limit of detection (LOD) was 5.4 µм. The linear range (LR) is between 25 and 125 µм. The sensor exhibits great potential for applications as a zinc detector for biological and environmental systems.
Nano hydroxyapatite (nHA) was synthesized from different methods. Spherical-like shaped nanoparti... more Nano hydroxyapatite (nHA) was synthesized from different methods. Spherical-like shaped nanoparticles of nHA were synthesized by chemical precipitation using Euclea Natalensis root extract as a template for the first time. In addition, traditional synthesis was performed, obtaining rod-like nanoparticles. The formation of nHA was confirmed using Fourier Transform Infrared (FTIR), X-Ray Diffraction (XRD), and Transmission Electron Microscopy (TEM). HA from green route presented a spherical-like shape with smooth surface. However, nanogrooves covered over the surface of nHA obtained without green template. Additionally, the cytotoxic effect of the nHA nanoparticles on L929 viability was assessed using MTS assay. The particles exhibited less cellular toxicity at shorter incubation periods. Spherical-like and rod-like nHA particles interact differently with fibroblast after 24 h of evaluation.
Chemistry is a basic science and it is present in most aspects of daily life. For being an instru... more Chemistry is a basic science and it is present in most aspects of daily life. For being an instrument of human formation, assume a special role that expands cultural horizons and autonomy in the exercise of citizenship. Therefore, it is important that this subject is taught from an everyday life perspective so that it fulfills its transforming role. One of the problems that most developing countries face in science, technology, engineering, and mathematics (STEM) education is the lack of conventional materials and reagents for practical classes and demonstrations. Therefore, the present work aimed to build a breathalyzer simulator to be applied in a teaching class of chemistry. Several steps were followed since the construction of the breathalyzer, tests of its functionality using local alcoholic drinks as a source of ethanol and finally strategies were proposed for its application in the classroom. The results showed that the simulated breathalyzer was constructed using locally available materials, such as chalk, pen tubes and birthday balloons. Furthermore, during the device functional test was possible to observe color changes resulting from the interaction between the ethanol in the drinks and the acidic dichromate solution. Based on the results obtained, strategies were proposed for its usage in the classroom.
Journal of Environmental Chemical Engineering, 2020
The application of an ultra-high-molecular-weight polyethylene-based (UHMWPE) nanocomposite with ... more The application of an ultra-high-molecular-weight polyethylene-based (UHMWPE) nanocomposite with nanohydroxyapatite (HA) and organophilic bentonite (OB) for adsorption of tetracycline (TC) was evaluated. The nanocomposite was prepared by combining the high energy grinding and the muffle heat treatment. Their formulation was investigated through complete experimental design (23), varying amount of OB, temperature and sintering time. The morphology and structure of the UHMWPE/HA/OB (ultra-high-molecular-weight polyethylene-based, nanohydroxyapatite and organophilic bentonite) were characterized using Fourier transform infrared (FTIR) spectroscopy, Brunauer-Emmett-Teller (BET), Scanning Electron Microscopy (SEM) and Electron Microscopy Transmission (TEM). The adsorption of TC in the composite was investigated through batch and fixed-bed experiments. For the batch experiments, the UHMWPE/HA/OB nanocomposite adsorbed 8.72 mg∙g−1 TC at 328.15 K, at neutral pH and at 24 h of reaction. The experimental adsorption data for kinetics were best described by the pseudo second order model (R2 = 0.989) and the isotherms followed the Freundlich model (R2 = 0.996). The thermodynamic investigation indicated that the adsorption was an endothermic reaction and that there is an affinity between the adsorbent and the adsorbate. According to the results of the fixed-bed column experiment, the breakthrough curve was plotted and the characteristic column parameters were evaluated, and the experimental data were better described by the Yan model (R2 = 0.980). Based on the results of the work the UHMWPE/HA/OB nanocomposite is very promising for the removal of contaminants in aqueous medium.
Sodium montmorillonite organically modified by octadecylammonium (Np-Clay) and zinc oxide nanopar... more Sodium montmorillonite organically modified by octadecylammonium (Np-Clay) and zinc oxide nanoparticles (Np-ZnO) were incorporated into chitosan (C) matrix in different proportions to evaluate its mechanical properties and antimicrobial activities. The composites were obtained by polymer intercalation method in solution using acetic acid (1% v/v) as solvent. The functional groups, thermic behavior and surface morphology of the chitosan film and of the composites prepared with different percentages of Np-Clay and Np-ZnO were characterized through Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) and scanning electron microscopy (SEM). The results showed that a combined effect of clay and zinc oxide increases significantly the mechanical properties of pure chitosan. FTIR results confirmed good compatibility among functional groups of chitosan, montmorillonite/metallic oxides. The Np-ZnO distribution became more uniform in chitosan films when the Np-clay was incorporated, thus, the Np-Clay compatibilizes the Np-ZnO with the chitosan and the mechanical properties improved and without affecting the antimicrobial activity of the films. The thermal degradation temperature of the chitosan did not change significantly with the addition of Np-Clay, but changes significantly with Np-ZnO addition. In antimicrobial test was found that the chitosan and Np-ZnO showed a synergistic effect against to Escherichia coli and Staphylococcus aureus. The addition of Np-ZnO and C-Clay in chitosan resulted in enhancement of mechanical and antimicrobial properties, turning this material prospective for food packaging applications.
Colloids and Surfaces A: Physicochemical and Engineering Aspects, 2019
The development of nanomaterials has attracted increasing attention recently. The study of new te... more The development of nanomaterials has attracted increasing attention recently. The study of new technologies to obtain these materials becomes extremely important since the majority of the nanomaterials synthesized require reagents and solvents. These reagents and solvents are sometimes toxic and may generate harmful residues to the environment and the health of living beings. Therefore, green synthesis is a potential alternative to obtain nanoparticles, sustainably, using ecological sources. This study developed a method of synthesizing the green of zirconia (ZrO2) nanoparticles using Euclea natalensis (Natal gwarri or Natal ebony tree with African origin) plant extract. Moreover, the adsorptive properties against tetracycline were evaluated. A factorial design was applied in the synthesis process, and an optimization of the reaction parameters (plant extract concentration, precursor concentration, and calcination temperature) was also described for the first time in literature. The nanoparticles were characterized using the XRD, FTIR and TEM techniques, and then subjected to batch adsorption tests. The samples presented the zirconia monoclinic and tetragonal phases, according to the XRD analysis, yielding materials with minimum crystallite sizes equal to 5.25 nm. The FTIR spectra confirmed the results obtained by the XRD, presenting band characteristic of the zirconia monoclinic and tetragonal phases. The particles had a rounded morphology with a very low average diameter ranging from 5.90 to 8.54 nm. Moreover, the nanoparticles were applied to the adsorption of tetracycline. The samples were synthesized with vegetal extract and precursor concentration equal to 50 g L−1 and 0.03 mol L−1, respectively, and calcination temperature of 550 °C, presented in the best performance (loading of 30.45 mg g−1). The adsorption capacity of the zirconia synthesized in this study was significantly higher than other common materials applied to tetracycline removal. The green synthesis procedure, as well as the application of the zirconia nanoparticles to the adsorption of an emerging pollutant, were promising.
Journal of Inorganic and Organometallic Polymers and Materials, 2019
The goal of this paper was to synthesize and characterize core–shell iron-carbon nanoparticles. F... more The goal of this paper was to synthesize and characterize core–shell iron-carbon nanoparticles. For this purpose, nanoparticles were synthetized via a hydrothermal co-precipitation route, applying a 22 factorial experimental design with a central point, and varying both the concentration of the iron precursor (iron nitrate) and the reaction temperature. The nanoparticles were characterized via the following analysis: vibrating sample magnometry (VSM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), energy dispersive X-ray spectroscopy (EDX), high resolution field emission gun scanning electron microscopy (SEM/FEG) and transmission electron microscopy (TEM) analysis. The results showed that the hydrothermal co-precipitation synthesis route enabled the production of Fe3O4–Fe2O3@C core–shell nanoparticles with dimensions between 4 and 8 nm. An increase in iron nitrate concentration and temperature during synthesis entailed a decrease in the remnant field and the magnetization of the nanoparticles.
The low interaction between ultra high molecular weight polyethylene (UHMWPE) and hydroxyapatite ... more The low interaction between ultra high molecular weight polyethylene (UHMWPE) and hydroxyapatite (HA) has been one of the problems that results in a composite material with low mechanical and tribological performance due to the formation of agglomerates and microstructural defects. These properties affect the quality of the material when used for total joint implants and other applications in hard tissue engineering. This study investigated the effect of the addition of organophilic bentonite (BO) into the interface HA and UHMWPE. The composite was prepared by wet milling in a planetary mill and then by compression molding. The composites samples were characterized by XRD, FTIR, SEM and DSC. The tensile and tribological mechanical properties were also evaluated. Furthermore, in vitro degradation using simulated blood fluid (SBF) and hemocompatibility was performed. The results suggest that the addition of 10 wt% of organophilic bentonite improved the interface between the UHMWPE and HA by exfoliation/intercalation, presenting the best results of modulus of elasticity, tensile strength, coefficient of friction and rate of wear. The composite UHMWPE/HA/BO-10 wt% presented low water absorption and induced the growth of apatite crystals on its surface. Additionally, its hemocompatibility index is within normal limits and induced a low adhesion and agglomeration of platelets in contact with human blood, evidencing that the UHMWPE/HA/BO-10 wt% composite is promising for application in bone tissue engineering.
A nanocomposite composed of ultrahigh-molecular-weight polyethylene (UHMWPE) with organophilic be... more A nanocomposite composed of ultrahigh-molecular-weight polyethylene (UHMWPE) with organophilic bentonite (OB) and nanohydroxyapatite (HA) was prepared by combining high-energy mill grinding with muffle heat treatment. This material was then characterized using Fourier transform infrared (FTIR) spectroscopy and scanning electron microscopy (SEM). Moreover, the adsorption capacity of UHMWPE/HA/OB was evaluated using methylene blue (MB) dye as a model adsorbate. After 20 h, the nanocomposite removed 48.8 mg∙g-1 of MB. The results showed that this nanocomposite has a good adsorption capacity and can be effective in the removal of contaminants in aqueous media.
RESUMO – O azul de metileno (AM) é um corante orgânico-catiônico com diversas aplicações. Porém, ... more RESUMO – O azul de metileno (AM) é um corante orgânico-catiônico com diversas aplicações. Porém, o seu descarte sem o devido tratamento pode causar a poluição dos recursos hídricos. Diversas tecnologias têm sido estudadas para a remoção destes contaminantes das águas residuárias, destacando-se a adsorção, por ser um dos métodos mais eficazes e economicamente viáveis. Diante disso, estudou-se a remoção do corante AM em soluções aquosas aplicando um novo compósito de polietileno de ultra alto peso molecular (UHMWPE) com hidroxiapatita (HA) e bentonita organofílica (BO). Esse novo adsorvente foi obtido e caracterizado por Microscopia Eletrônica de Varredura (MEV). Para os ensaios de adsorção, mediu-se a concentração do corante no meio líquido por espectroscopia na região UV/visível. Os resultados experimentais mostraram que o compósito de UHMWPE/HA/BO possui propriedades favoráveis para utilização como adsorvente na remoção de AM, atingindo o percentual de remoção de 38% nas condições testadas.
With the increasing demand of biomaterials, numerous studies have been developed seeking to impro... more With the increasing demand of biomaterials, numerous studies have been developed seeking to improve its properties through new obtaining and manufacturing processes. This work aimed to aggregate antimicrobial property to a biocomposite constituted of a matrix of ultra-high molecular weight polyethylene (UHMWPEE) and hydroxyapatite, by the incorporation of zinc oxide nanoparticles. The samples were prepared based on a standard composition containing 95.0 wt% of UHMWPEE and 5.0 wt% of hydroxyapatite (blank). Three compositions were evaluated ranging the amount of zinc oxide nanoparticles incorporated in the standard sample. It was observed that the increase of zinc oxide concentration aggregate a good antibacterial property in the samples tested without cause significant changes in the mechanical properties of the composites.
Core-shell Fe 3 O 4 @C nanoparticles consist of a magnetic core and carbon coating, and exhibit h... more Core-shell Fe 3 O 4 @C nanoparticles consist of a magnetic core and carbon coating, and exhibit high adsorptive capacity, easy magnetic separation and reusability. Due to these properties, core–shell Fe 3 O 4 @C nanoparticles have great potential application in adsorption, separation and wastewater treatment. Magnetic separation based on the super paramagnetic Fe 3 O 4 has received considerable attention and is widely used for the removal of dye, oil pharmaceuticals and metals from water due to its high efficiency and economic viability. Therefore, the main characteristics of the core-shell Fe 3 O 4 @C nanoparticles, the different types of synthesis, as well as the main applications for the removal of water pollutants were reviewed. In this brief review, an overview of the basic properties of the Fe 3 O 4 @C core-shell nanoparticles are given, and the most important and more frequently used methods for the synthesis of Fe 3 O 4 @C core-shell nanoparticles have been summarized along with the description of its adsorbent application potential. Highlights • Magnetic core-shell Fe 3 O 4 @C nanoparticles combine excellent adsorptive capacity and easy magnetic separation. • Core-shell nanoparticles show high regeneration capability. • The use of magnetic core-shell Fe 3 O 4 @C nanoparticles provides over 90% removal of pollutants in aqueous media. • Magnetic core-shell Fe 3 O 4 @C nanoparticles regeneration has been manifesting great potential in water treatment.
Nowadays, the main application of coal mine in the world is to produce energy through thermoelect... more Nowadays, the main application of coal mine in the world is to produce energy through thermoelectric power plants. Energy generation is always associated with the production of enormous amounts of ashes, both bottom and fly ashes. The main objective of this work is to study the effect of time, temperate and concentration on Synthetic zeolites produced from utilizing minerals of coal bottom ash. However, for the factor significance analysis, factorial planning of two levels and three factors was used, where eight experiments were obtained, and the results of FTIR transmittance showed favorable variation in time and temperature, and the variation of the NaOH concentration was not significant. It was concluded that the concentration of NaOH only influences the zeolites formation when combined with the crystallization time.
In coal-burning processes combustion products has been the biggest problem for environmental pre... more In coal-burning processes combustion products has been the biggest problem for environmental prevention. This work aims at the use of bottom ashes, from the burning of mineral coal in thermal power plants, in the synthesis of zeolites. The motivation of this study was based on studies which show the presence of aluminosilicates in coal ash. Zeolites are aluminosilicates that exhibit crystalline structural arrangement and have high adsorption properties. The zeolite synthesis process has as its sole step the use of bottom ashes as alternative sources silica and aluminum. The zeolite materials obtained had a specific area of 771 m 2 /g, being attractive results due to the fact that the bottom ash has in its composition about 7.0% Fe, element that disadvantages the nucleation and formation of crystals process.
Transmission infrared spectroscopy (FTIR) was used to study the effect of the temperature and con... more Transmission infrared spectroscopy (FTIR) was used to study the effect of the temperature and concentration of octadecylamine (surfactant) in the conformation state of amine chains incorporated in a bentonite matrix by organophilization process. The temperature is the most important factor in conformational changes-gauche/trans. Whereas the simultaneous increase of the temperature and concentration of surfactant favors the disordered conformation-gauche. This result is very important in the development of organo-bentonite based polymeric nanocomposites because the intercalation of the polymer in the galleries of the organo-bentonite is dependent on the conformation of the alkyl chains.
6a Edição do Workshop de Orgãos Artificiais, Biomateriais e Engenharia de Tecidos (OBI), 2019
Hydroxyapatite [Ca 10 (PO 4 ) 6 (OH) 2 ] (HAp) is a calcium phosphate mineral of great interest i... more Hydroxyapatite [Ca 10 (PO 4 ) 6 (OH) 2 ] (HAp) is a calcium phosphate mineral of great interest in biomaterials development because it is the main component of the mineral phase of bones and teeth’s of animals and humans. HAp plays a key role in the biomedical field due to its non-toxicity, anti-inflammatory property, osteointegrity, biocompatibility, and other properties. Some of its applications in tissue engineering involve bone repair, bone augmentation, coating of implants, and fillers for bones and teeth. Besides, HAp can function as a drug delivery system due to its porous nature, which gives the nanoparticles a larger surface area. However, the use of organic templates in order to obtain HAp nanoparticles with a specific shape, morphology, size, and textural properties makes it impractical from an ecological and cost-effective standpoint. Throughout the last decade, several attempts to improve synthetic procedures have been under development. Recently, special attention has been given to the application of plant extracts as substitutes for organic templates, though they are not extensively reported in literature. Therefore, this brief review aims to examine the existing routes for synthesis of hydroxyapatite nanoparticles. Then the focus shifts to an overview of greener procedures and an outlook of their benefits in biomedical applications.
In recent years, the development of nanomaterials and their applications has been the object of s... more In recent years, the development of nanomaterials and their applications has been the object of several studies. These new materials, on the nanometer scale, have attracted extensive interest due to their small size. Conventionally, most methods of synthesizing the nanoparticles use solvents and synthetic surfactants that are expensive and harmful to human health and the environment. The green synthesis appears as an alternative method and has great potential for the synthesis of nanoparticles. The nanoparticles can be applied in the adsorption process. However, it is still a challenge to obtain sufficient information on how the nanoparticle production process occurs and how it will interact with the contaminant at the molecular level.
As cinzas de carvão mineral são sub produtos do processo de combustão em centrais térmicas, e são... more As cinzas de carvão mineral são sub produtos do processo de combustão em centrais térmicas, e são dividas em: cinzas volantes ou leves, e cinzas de fundo ou pesada, sendo que as suas propriedades dependem, na maioria das vezes, de fatores de queima. O presente trabalho faz um estudo de aplicação de cinzas pesadas como fontes alternativas de aluminossilicatos na síntese de zeólitas faujasitas. Sabe-se que, as cinzas incluem na sua composição química uma pequena quantidade de elementos nocivos, tais como o As, Mn, V, Pb, etc., estes, são separados durante o processo de cristalização de zeólitas, e, efetivamente, incorporados em zeólitas. As zeólitas foram sintetizadas em um sistema com duas variáveis, tempo de cristalização e temperatura de cristalização.Com base nos resultados de MEV e DRX conclui-se que as cinzas pesadas de carvão mineral são fontes alternativas de alumino e silício para a síntese de adsorventes zeolíticos, sendo que, este trabalho desenvolveu uma das grandes aplicações destas cinzas na obtenção de materiais de maior valor agregado.
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Papers by DL P Macuvele
been given to the application of plant extracts as substitutes for organic templates, though they are not extensively reported in literature. Therefore, this brief review aims to examine the existing routes for synthesis of hydroxyapatite nanoparticles. Then the focus shifts to an overview of greener procedures and an outlook of their benefits in biomedical applications.
de maior valor agregado.