Calcium ferrites for phosphate adsorption and recovery from wastewater.

In this study, calcium ferrites with different Ca : Fe atomic ratios (1 : 1, 1 : 2, 1 : 3 and 2 : 1) were prepared from Ca and Fe nitrates treated at 300, 700 and 900 °C and evaluated for phosphate adsorption and recovery from wastewater. TG, XRD, Mössbauer spectroscopy, SEM, VSM magnetic measurements, and BET analyses showed the formation of two different calcium ferrite phases, i.e., CaFe2O4 and Ca2Fe2O5 at 700 and 900 °C. The adsorption results indicated that the formation of calcium ferrite structure is critical for phosphate adsorption/recovery. Evaluation of the pH, initial phosphate concentration, contact time, coexisting ions and desorption conditions showed remarkable adsorption capacities of 62-75 mg g-1 for CaFe1:2-700 and 28-43 mg g-1 for CaFe1:2-900. The phosphate adsorption on the Ca ferrite surfaces is so strong that the recovery/desorption showed limited efficiencies, e.g., 15-39%.

Determination of settled dust sources by analytical techniques and chemical mass balance receptor model.

The identification of sources that produce particulate atmospheric matter (PM) can be of paramount importance for the reduction of air pollution and the development of environmental policies. In order to identify the environmental impact resulting from industrial metallurgical activities in the Metropolitan Region of Vitória, ES, Brazil, it was investigated the contribution to PM that result from industrial activities and from local natural sources. For this purpose, analytical techniques were used to identify the apportionment of sources that contribute to the formation of insoluble settled dust collected at two points near the city of Vitória. Samples of soil, iron ore, limestone, coal, iron ore pellets, sinter, coke, slag, environmental samples of settled dust, and samples representative of the actual flows of materials used in an integrated steel mill were analyzed. Physicochemical characterizations, based on X-ray diffraction and 57Fe Mössbauer spectroscopy of ferruginous compounds found in sources and receptor samples, revealed the presence of highly crystallized hematite and low crystallized hematite. The latter is primarily found in soil samples, while well-crystallized hematite is found in natural samples from iron ores or after thermo-chemical processes applied during the industrial transformation of raw materials, as it happens during the production of pellets. Ferrous crystallographic forms α-FeOOH and Fe5HO8·4H2O, observed in environmental and soil samples, were also found in samples from industrial sources. Source apportionment of carbon based on the IMPROVE_A protocol for thermal/optical carbon analysis showed the participation of the elementary carbon fractions, separating contributions originated from coke and coal sources in the environmental samples. These results allowed a significant reduction of collinearity between source profiles in the application of the chemical mass balance receptor model "EPA-CMB8.2" receptor model. Consequently, it was possible to distinguish sources that process mainly ferrous and carbonaceous materials, identifying the contribution of different sources to the settled dust collected.

Solid-state properties of pink clay from Jequitinhonha Valley in Brazil for pre-formulation study

Abstract Clay minerals are still widely used in pharmaceutical products for human health and cosmetic purposes. Pre-formulation studies were conducted to identify solid-state properties of pink clay, a sample from Diamantina, Brazil. Among the solid properties to be analyzed, we have selected type identification, iron phases, crystallinity, powder flow characteristics, thermal behavior, and non-isothermal phase transition kinetics. The pink clay is composed of (1:1) clay type and kaolinite as the main component. The Mössbauer spectrum of pink clay shows Fe3+(α-Fe2O3) Clay minerals are still widely used in pharmaceutical products for human health and cosmetic purposes. Pre-formulation studies were conducted to identify solid-state properties of pink clay, a sample from Diamantina, Brazil. Among the solid properties to be analyzed, we have selected type identification, iron phases, crystallinity, powder flow characteristics, thermal behavior, and non-isothermal phase transition kinetics. The pink clay is composed of (1:1) clay type and kaolinite as the main component. The Mössbauer spectrum of pink clay shows Fe3+(α-Fe2O3) hematite, Fe2+, and Fe3+ with large Δ/2ξq of about 2.80 and 2.69 mm.s-1 respectively, related to iron silicates, most likely pyroxene, and a superparamagnetic Fe3+. Pink clay exhibits poor flow properties. The thermal behavior indicates a phase-transition between 400 - 600 ºC associated with the dehydroxylation of the pink clay system requiring ~300 kJ mol-1, being constant until the process reaches a conversion of ~50% when the energy is enhanced to ~530 kJ mol-1, concluding the whole dehydroxylation process (α=80%). Solid-state properties and characteristics found for the pink clay must be considered for the proper design of formulations. This type of clay shows unique pharmaceutical properties that can be favorably exploited by the cosmetic industry

Heating Capacity and Biocompatibility of Hybrid Nanoparticles for Magnetic Hyperthermia Treatment.

Cancer is one of the deadliest diseases worldwide and has been responsible for millions of deaths. However, developing a satisfactory smart multifunctional material combining different strategies to kill cancer cells poses a challenge. This work aims at filling this gap by developing a composite material for cancer treatment through hyperthermia and drug release. With this purpose, magnetic nanoparticles were coated with a polymer matrix consisting of poly (L-co-D,L lactic acid-co-trimethylene carbonate) and a poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) triblock copolymer. High-resolution transmission electron microscopy and selected area electron diffraction confirmed magnetite to be the only iron oxide in the sample. Cytotoxicity and heat release assays on the hybrid nanoparticles were performed here for the first time. The heat induction results indicate that these new magnetic hybrid nanoparticles are capable of increasing the temperature by more than 5 °C, the minimal temperature rise required for being effectively used in hyperthermia treatments. The biocompatibility assays conducted under different concentrations, in the presence and in the absence of an external alternating current magnetic field, did not reveal any cytotoxicity. Therefore, the overall results indicate that the investigated hybrid nanoparticles have a great potential to be used as carrier systems for cancer treatment by hyperthermia.

Tunable magnetothermal properties of cobalt-doped magnetite-carboxymethylcellulose ferrofluids: smart nanoplatforms for potential magnetic hyperthermia applications in cancer therapy.

Magnetite nanoparticles are one of the most promising ferrofluids for hyperthermia applications due to the combination of unique physicochemical and magnetic properties. In this study, we designed and produced superparamagnetic ferrofluids composed of magnetite (Fe3O4, MION) and cobalt-doped magnetite (Co x -MION, x = 3, 5, and 10% mol of cobalt) nanoconjugates through an eco-friendly aqueous method using carboxymethylcellulose (CMC) as the biocompatible macromolecular ligand. The effect of the gradual increase of cobalt content in Fe3O4 nanocolloids was investigated in-depth using XRD, XRF, XPS, FTIR, DLS, zeta potential, EMR, and VSM analyses. Additionally, the cytotoxicity of these nanoconjugates and their ability to cause cancer cell death through heat induction were evaluated by MTT assays in vitro. The results demonstrated that the progressive substitution of Co in the magnetite host material significantly affected the magnetic anisotropy properties of the ferrofluids. Therefore, Co-doped ferrite (Co x Fe(3-x)O4) nanoconjugates enhanced the cell-killing activities in magnetic hyperthermia experiments under alternating magnetic field performed with human brain cancer cells (U87). On the other hand, the Co-doping process retained the pristine inverse spinel crystalline structure of MIONs, and it has not significantly altered the average nanoparticle size (ca.∼7.1 ± 1.6 nm). Thus, the incorporation of cobalt into magnetite-polymer nanostructures may constitute a smart strategy for tuning their magnetothermal capability towards cancer therapy by heat generation.

Use of iron mining tailings from dams for carbon nanotubes synthesis in fluidized bed for 17α-ethinylestradiol removal.

This work reports the use of an iron ore tailings from waste dam as a catalyst and support for carbon nanotubes synthesis and their application in the adsorption of the 17α-ethinylestradiol hormone. The synthesis was carried out by Chemical Vapor Deposition (CVD) in a Fluidized Bed system using: ethylene at temperatures of 500, 600 and 700 °C, and acetonitrile at 500, 600, 700, 800 and 900 °C. The transmission electron microscopy (TEM) results showed that the two higher temperatures in each case favored the formation of nanostructures like carbon nanotubes (CNTs), with good yields. The ethylene source generated classic tubular structures of multiple walls. On the other hand, acetonitrile provided the formation of tubes with less organization, known as bamboo like. This morphology was caused by the insertion of nitrogen into the graphite structure (doping), which originates from the carbon source. The adsorptive capacity of the materials for 17α-Ethinylestradiol removal ranging from 9.2 mg g-1 to 22.3 mg g-1. The kinetic and adsorption isotherm studies were also performed for the systems. As for kinetics, all of them presented pseudo-second order behavior. In relation to the type of isotherm, the systems showed Freundlich behavior, that is, the adsorption occurs in multiple layers. Finally, it was concluded that the use of an iron ore tail as a catalyst in the production of CNTs by CVD is feasible. The materials synthesized still had good adsorptive capacity for an emerging contaminant, thus this study allowed the investigation of two environmental problems.

Tailings from Fundão Tragedy: Physical-Chemical Properties of the Material That Remains by Candonga Dam.

In this work, samples of Fe mining tailings from the collapsed Fundão Dam, Brazil, which were retained by the Candonga hydroelectric power plant, were characterized by various techniques. Quartz, hematite, kaolinite, and goethite were identified as the main phases present. The composition, homogeneity, and relatively low (~1%) organic matter content indicate potential for usage of these tailings in civil constructions. The next step of this work is to investigate such applications. If their feasibility is confirmed, the goal is to use this material for construction in the areas affected by the Fundão Dam rupture. This use will lead to positive socio-environmental impacts in these regions, where tailings still need to be removed and damaged infrastructure needs to be repaired. Integr Environ Assess Manag 2020;16:636-642. © 2019 SETAC.

Neste trabalho, amostras do rejeito de mineração de ferro, proveniente do rompimento da barragem de Fundão e retidas pela usina hidroelétrica de Candonga, foram caracterizadas por diversas técnicas. Quartzo, hematita, caulinita e ghoetita foram identificadas como as principais fases presentes no rejeito. A composição, homogeneidade e teor de matéria orgânica relativamente baixo, cerca de 1%, indicam uso potencial deste material em construção civil. O próximo passo deste trabalho é investigar tais aplicações. Se a viabilidade for confirmada, o objetivo é utilizar esse material para obras nas áreas afetadas pelo rompimento da barragem de Fundão. Isso contribuirá para reduzir os impactos socioambientais nessas regiões, as quais ainda necessitam da remoção do rejeito e de reparos na infraestrutura danificada. Integr Environ Assess Manag 2020;16:636-642.

Synthesis and characterization of iron oxide nanoparticles/carboxymethyl cellulose core-shell nanohybrids for killing cancer cells in vitro.

Novel core-shell superparamagnetic nanofluids composed of magnetic iron oxide (Fe3O4, MION) and cobalt-doped (CoxFe3-xO4, Co-MION) nanoparticles functionalized with carboxymethyl cellulose (CMC) ligands were designed and produced via green colloidal aqueous process. The effect of the degree of substitution (DS = 0.7 and 1.2) and molecular mass (Mw) of CMC and cobalt doping concentration on the physicochemical and magnetic properties of these nanoconjugates were comprehensively investigated using Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction, transmission electron microscopy (TEM) with selected area electron diffraction, X-ray fluorescence, dynamic light scattering (DLS), zeta potential (ZP) analysis, vibrating sample magnetometry (VSM) and electron paramagnetic resonance spectroscopy (EPR). The results demonstrated the effect of concentration of carboxylate groups and Mw of CMC on the hydrodynamic dimension, zeta potential, and generated heat by magnetic hyperthermia of MION nanoconjugates. Co-doping of MION showed significant alteration of the electrostatic balance of charges of the nanoconjugates interpreted as effect of surface interactions. Moreover, the VSM and EPR results proved the superparamagnetic properties of these nanocolloids, which were affected by the presence of CMC and Co-doping of iron oxide nanoparticles. These magnetic nanohybrids behaved as nanoheaters for killing brain cancer cells in vitro with prospective future applications in oncology and nanomedicine.

Ferruginous compounds in the airborne particulate matter of the metropolitan area of Belo Horizonte, Minas Gerais, Brazil.

Samples of soil, iron ore, and airborne particulate matter (size <10 µm) were analyzed with the main goal of investigating the differentiating physicochemical properties of their ferruginous compounds. These data were used to identify whether the sources of airborne particulate matter in the metropolitan area of Belo Horizonte, Minas Gerais, Brazil, are either from natural origin, as, for instance, re-suspension of particles from soil, or due to anthropogenic activities, meaning that it would be originated from the many iron ore minings surrounding the metropolitan area. Numerical simulations were used to model the atmospheric dispersion of the airborne particulate matter emitted by iron mining located at the Iron Quadrangle geodomain, Minas Gerais. Results from these numerical simulations supported identifying the sites with the highest concentrations of airborne particulate matter in the metropolitan area. Samples of these suspended materials were collected at the selected sites by using high-volume air samplers. The physicochemical features of the solid materials were assessed by X-ray fluorescence, X-ray diffraction, magnetometry, and 57Fe Mössbauer spectroscopy. The soil materials were found to be rich in quartz, aluminum, organic matter, and low contents of iron, mainly as low crystalline iron oxides. The samples of the iron ores, on the other hand, contain high concentration of iron, dominantly as relatively pure and crystalline hematite (α-Fe2O3). The samples of the airborne particulate matter are rich in iron, mainly as hematite, but contained also quartz, aluminum, and calcium. Mössbauer spectroscopy was used to evaluate the hyperfine structure of 57Fe of the hematite both from the iron ore and the soil samples. The structural characteristics of the hematite of these particulate materials were further explored. The direct influence of the iron ore mining on the composition of the airborne particulate matter was clearly evidenced based on the trace ability of hematite to its source of emission. Even the atmospheric air on regions relatively far away from the mining activities is also significantly influenced.

Use of iron and bio-oil wastes to produce highly dispersed Fe/C composites for the photo-Fenton reaction.

This work describes the synthesis, characterization, and application of an active heterogeneous photo-Fenton system obtained from two different wastes, i.e., laterite (an iron mining waste) and the acid aqueous fraction (AAF) from bio-oil production. AAF with high acidity (ca. 3 molH+ L-1) and organic concentration (25 wt.%) obtained from biomass flash pyrolysis was used for the efficient extraction of Fe3+ from laterite waste. After extraction, the mixture Fe3+/AAF was dried and treated at different temperatures, i.e., 500, 650, and 800 °C, to obtain Fe/C reactive composites. Mössbauer, XRD, TG, elemental analyses, and SEM/EDS showed the presence of highly disperse Fe oxide nanoparticles at 500 and 650 °C and Fe0 particles in the material obtained at 800 °C with carbon contents varying from 74 to 80 %. The three composites were tested as heterogeneous catalysts in the photo-Fenton reaction for the oxidation of the model dye contaminant methylene blue, showing high activities at neutral pH.

Controlled formation of reactive Fe particles dispersed in a carbon matrix active for the oxidation of aqueous contaminants with H2O2.

In this work, reactive iron nanoparticles dispersed in a carbon matrix were produced by the controlled thermal decomposition of Fe(3+) ions in sucrose. During the sucrose decomposition, the Fe(3+) ions are reduced to form iron nanometric cores dispersed in a porous carbonaceous matrix. The materials were prepared with iron contents of 1, 4, and 8 wt.% and heated at 400, 600, and 800 °C. Analyses by X-ray diffraction, Mössbauer spectroscopy, magnetization measurements, Raman spectroscopy, termogravimetric analyses, BET surface area, scanning, and transmission electron microscopy showed that at 400 °C, the materials are composed essentially of Fe3O4 particles, while treatments at higher temperatures, i.e., 600 and 800 °C, produced phases such as Fe(0) and Fe3C. The composites were tested for the oxidation of methylene blue with H2O2 by a Fenton-type reaction and also H2O2 decomposition, showing better performance for the material containing 8 % of iron heated at 400 and 600 °C. These results are discussed in terms of Fe(2+) surface species in the Fe3O4 nanoparticles active for the Fenton reaction.

Temperature and time dependence on ZnS microstructure and phases obtained through hydrothermal decomposition of diethyldithiocarbamate complexes.

Zinc sulphide was obtained through hydrothermal decomposition of [Zn(S2CNEt2)] under different experimental conditions such as temperatures and reaction times. Hydrothermal reactions were carried out in a stainless steel autoclave at 160, 180 and 200 °C for 3, 6 and 24 hours. The obtained products were characterized using X-ray diffraction, scanning and high resolution transmission electron microscopies. Particle size and microstrain were determined by Rietveld refinement of experimental X-ray diffraction patterns. The obtained crystal size values were in the range of 6.1 to 30 nm and as the temperature and reaction times increase the particle size also increases. Band gap values are in the range of 3.34 to 3.60 eV and are highly dependent on the crystal microstrain. The catalyst activities were studied through the degradation of methylene blue dye solutions under ultraviolet radiation.

Potential application of highly reactive Fe(0)/Fe3O4 composites for the reduction of Cr(VI) environmental contaminants.

We describe the use of highly reactive Fe(0)/Fe3O4 composites for the reduction of Cr(VI) species in aqueous medium. The composites were prepared by simple mechanical alloying of metallic iron and magnetite in different proportions, i.e. Fe(0) 25, 50, 75 and 90wt%. While after 3h of reaction pure Fe(0) and pure Fe3O4 showed only a low reduction efficiency of 15% and 25% Cr(VI) conversion, respectively, the composites, in particular Fe(0)(25wt%)/Fe3O4, showed a remarkable activity with ca. 65% Cr(VI) conversion. Kinetic experiments showed a high reaction rate during the first 3h, which subsequently decreased strongly, probably due to a pH increase from 6 to 8. Experiments with composites based on Fe(0)/alpha-Fe2O3, Fe(0)/gamma-Fe2O3 and Fe(0)/FeOOH showed very low activities, suggesting that Fe(oct)2+ in the magnetite structure plays an important role in the reaction. Scanning and high resolution electron microscopies and Mössbauer spectra (transmission and conversion electron Mössbauer spectroscopy) indicated that the mechanical alloying process promotes a strong interaction and interface between the metallic and oxide phases, with the Fe(0) particles completely covered by Fe3O4 particles. The high efficiency of the composite Fe(0)/Fe3O4 for Cr(VI) reduction is discussed in terms of a special mechanism where an electron is transferred from Fe(0) to magnetite to reduce Fe(oct)3+ to Fe(oct)2+, which is active for Cr(VI) reduction.

Uma alternativa mecânica com emprego de forças magnéticas para a desimpactação dentária / A mechanical alternative with employment of magnetic force for the tooth desimpactation

OBJETIVO: o presente trabalho teve como finalidade avaliar clinicamente uma nova alternativa mecânica para a erupção guiada ao plano oclusal de um dente pré-molar impactado empregando magnetos atrativos da liga samário-cobalto. METODOLOGIA: o tratamento cirúrgico-ortodôntico foi realizado em uma paciente jovem de 11 anos portadora de oclusão de Classe I de Angle, com impactação do segundo pré-molar inferior direito. O sistema magnético empregado consistiu de um magneto colado com resina fotopolimerizável sobre a superfície vestibular do dente impactado e um outro pólo magnético rígido incrustado em um aparelho banda alça. Previamente à instalação do sistema magnético no meio bucal, os magnetos foram caracterizados através de análise de fluorescência, difração de raios X e nível de magnetização. A relação força/distância empregada foi quantificada, os magnetos foram medidos e a geometria magnética bucal estabelecida. RESULTADOS: o tempo empregado na desimpactação foi de 40 dias e foram necessárias duas ativações magnéticas por aproximação dos magnetos neste intervalo. A opção magnética neste caso clínico foi bastante eficaz tanto em relação ao tempo de tratamento quanto em relação ao conforto proporcionado ao paciente. Os magnetos empregados geraram um campo de força contínuo e autônomo não sendo necessária a utilização de fios metálicos como guias de orientação na erupção e nem elásticos de tracionamento. CONCLUSÃO: esta possibilidade terapêutica poderá ser útil em desimpactações mais profundas tais como os caninos ectópicos, cuja ocorrência é freqüente.