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The synthesis by coprecipitation of Layered Double Hydroxides (LDHs) is governed by the stages of nucleation and crystal growth associated with the efficiency of the mixing and dispersion process of the reagents. Mixing efficiency is related to process variables, such as agitation speed, type of impeller and baffles presence, among others. In this context, this work proposes an analysis of these variables in a batch reactor, using a 23 factorial design employing the factors: acceleration speed (200 and 1000 rpm), mixing time (2 and 18 h) and presence or absence of baffles. The results were evaluated quantitatively (amount of LDH produced, time and amount of base for the formation of LDHs to begin) and qualitatively (mixing aspects, sedimentation ad grinding). The significant factors affecting the amount of LDH produced (51.94-80.81 g) were agitation speed and aging time. These factors were also correlated with the structural characteristics of the materials produced, such as crystallinity, crystallite size (70.99-174.79 nm), surface area (69.81-97.62 m2/g), pore volume (0.28-0.59 cm3/g), and pore diameter (11.40-34.66 nm). LDHs produced at higher agitation rates (1000 rpm) and longer aging times (18 h) yielded higher quantities of materials (80.81 g) with improved structural characteristics. The study highlights the importance of systematically exploring the synergistic effect between process variables, emphasizing the research potential in this area.
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Conobea scoparioides (Plantaginaceae) is an herbaceous plant known as "pataqueira" that grows wild in seasonally wet areas of the Amazon region. It is used for aromatic baths and anti-protozoan remedies by the Brazilian Amazon native people. The main volatile compounds identified in the essential oil of "Pataqueira" were the phenolic monoterpenes thymol and thymol methyl ether and their precursors, the monoterpene hydrocarbons α-phellandrene and p-cymene. A hydrotalcite synthesized from blast-furnace slag exhibited a 3:2 (Mg/Al) molar ratio, and this layered double hydroxide (LDH) was evaluated as a catalyst in converting the main monoterpenes of the "Pataqueira" oil. This action significantly increased the thymol content, from 41% to 95%, associated with the percentual reduction in other main components, such as thymol methyl ether, α-phellandrene, and p-cymene. The LDH reaction showed a strong tendency towards producing hydroxylated derivatives, and its behavior was similar to the hypothetical plant biosynthetic pathway, which leads to the production of the monoterpenes of "Pataqueira" oil. Thymol and its derivatives are potent antiseptics applied in pharmaceutical and hygienic products as antibacterial, antifungal, and antioxidant properties, among others. The present work reports a natural source with a high thymol content in aromatic plants from the Amazon, with evident economic value.
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The chemical recycling of poly(ethylene terephthalate) (PET) residues was performed via glycolysis with ethylene glycol (EG) over Mg-Fe and Mg-Al oxide catalysts derived from layered double hydroxides. Catalysts prepared using the high supersaturation method (h.s.c.) presented a higher surface area and larger particles, but this represented less PET conversion than those prepared by the low supersaturation method (l.s.c.). This difference was attributed to the smaller mass transfer limitations inside the (l.s.c.) catalysts. An artificial neural network model well fitted the PET conversion and bis(2-hydroxyethyl) terephthalate (BHET) yield. The influence of Fe in place of Al resulted in a higher PET conversion of the Mg-Fe-h.s.c. catalyst (~95.8%) than of Mg-Al-h.s.c. (~63%). Mg-Fe catalysts could be reused four to five times with final conversions of up to 97% with reaction conditions of EG: PET = 5:1 and catalyst: PET = 0.5%. These results confirm the Mg-Fe oxides as a biocompatible novel catalyst for the chemical recycling of PET residues to obtain non-toxic BHET for further polymerization, and use in food and beverage packaging.
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N-acetyl-L-cysteine (NAC), a derivative of the L-cysteine amino acid, presents antioxidant and mucolytic properties of pharmaceutical interest. This work reports the preparation of organic-inorganic nanophases aiming for the development of drug delivery systems based on NAC intercalation into layered double hydroxides (LDH) of zinc-aluminum (Zn2Al-NAC) and magnesium-aluminum (Mg2Al-NAC) compositions. A detailed characterization of the synthesized hybrid materials was performed, including X-ray diffraction (XRD) and pair distribution function (PDF) analysis, infrared and Raman spectroscopies, solid-state 13carbon and 27aluminum nuclear magnetic resonance (NMR), simultaneous thermogravimetric and differential scanning calorimetry coupled to mass spectrometry (TG/DSC-MS), scanning electron microscopy (SEM), and elemental chemical analysis to assess both chemical composition and structure of the samples. The experimental conditions allowed to isolate Zn2Al-NAC nanomaterial with good crystallinity and a loading capacity of 27.3 (m/m)%. On the other hand, NAC intercalation was not successful into Mg2Al-LDH, being oxidized instead. In vitro drug delivery kinetic studies were performed using cylindrical tablets of Zn2Al-NAC in a simulated physiological solution (extracellular matrix) to investigate the release profile. After 96 h, the tablet was analyzed by micro-Raman spectroscopy. NAC was replaced by anions such as hydrogen phosphate by a slow diffusion-controlled ion exchange process. Zn2Al-NAC fulfil basic requirements to be employed as a drug delivery system with a defined microscopic structure, appreciable loading capacity, and allowing a controlled release of NAC.
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The development of biomaterials has a substantial role in pharmaceutical and medical strategies for the enhancement of life quality. This review work focused on versatile biomaterials based on nanocomposites comprising organic polymers and a class of layered inorganic nanoparticles, aiming for drug delivery (oral, transdermal, and ocular delivery) and tissue engineering (skin and bone therapies). Layered double hydroxides (LDHs) are 2D nanomaterials that can intercalate anionic bioactive species between the layers. The layers can hold metal cations that confer intrinsic biological activity to LDHs as well as biocompatibility. The intercalation of bioactive species between the layers allows the formation of drug delivery systems with elevated loading capacity and modified release profiles promoted by ion exchange and/or solubilization. The capacity of tissue integration, antigenicity, and stimulation of collagen formation, among other beneficial characteristics of LDH, have been observed by in vivo assays. The association between the properties of biocompatible polymers and LDH-drug nanohybrids produces multifunctional nanocomposites compatible with living matter. Such nanocomposites are stimuli-responsive, show appropriate mechanical properties, and can be prepared by creative methods that allow a fine-tuning of drug release. They are processed in the end form of films, beads, gels, monoliths etc., to reach orientated therapeutic applications. Several studies attest to the higher performance of polymer/LDH-drug nanocomposite compared to the LDH-drug hybrid or the free drug.
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Oil emulsified in water is one of the most difficult mixtures to treat due to the good stability of emulsions, so there is a growing demand for more efficient methods for separating immiscible oil/water mixtures. In this context, the focus of this study was to obtain an adsorbent for the selective treatment of a simulated oily wastewater. To this aim, a modified hydrotalcite sample with hydrophobic and magnetic characteristics was prepared and characterized. Initially, the effect of sodium dodecyl sulfate (SDS) amount on the adsorbent characteristics was evaluated (266-800 mgSDS g-1LDH). The hydrophobic hydrotalcite (LDH-SDS) containing 533 mgSDS g-1LDH (LDH-SDS2) presented a higher interlayer space where the surfactant molecules were arranged perpendicular to the lamellae, allowing better access to the hydrotalcite pores and facilitating the selective adsorption of oil compounds. Moreover, the synergistic association of hydrophobic properties with super-wetting and effective adhesion oil to Fe3O4 favoured the selective adsorption of the simulated oily wastewater onto the hydrophobic and magnetic hydrotalcite (LDH-MSDS), facilitating the post-treatment separation. The kinetic analysis demonstrated that the adsorption equilibrium was attained in 120â min and the pseudo-second order model was the most suitable for predicting the removal of total organic carbon (TOC) from the simulated oily wastewater. The Langmuir model described very well the equilibrium experimental data, with a maximum adsorption capacity for TOC removal using LDH-MSDS of 659.9â mg g-1. Therefore, the modified hydrotalcite prepared in this study showed intrinsic characteristics that make it a promising adsorbent for the selective treatment of oily wastewaters.
Asunto(s)
Aguas Residuales , Contaminantes Químicos del Agua , Cinética , Hidróxido de Aluminio/análisis , Aceites , Adsorción , Fenómenos Magnéticos , Contaminantes Químicos del Agua/químicaRESUMEN
Coumaric acid (CouH), an antioxidant molecule assimilated by food consumption, was intercalated into layered double hydroxide (LDH) nanocarrier, having zinc and aluminium ions in the layers (LDH-Cou), to evaluate its pharmacological activity through in vitro and in vivo assays in mice. Therefore, the following tests were performed: coumarate delivery in saline solution, fibroblasts' cell viability using neutral red, peritonitis induced by carrageenan, formalin test, acetic-acid-induced writhing, and tail-flick assay, for the non-intercalated CouH and the intercalated LDH-Cou system. Furthermore, different pharmacological pathways were also investigated to evaluate their possible anti-inflammatory and antinociceptive mechanisms of action, in comparison to traditionally used agents (morphine, naloxone, caffeine, and indomethacin). The LDH-Cou drug delivery system showed more pronounced anti-inflammatory effect than CouH but not more than that evoked by the classic non-steroidal anti-inflammatory drug (NSAID) indomethacin. For the analgesic effect, according to the tail-flick test, the treatment with LDH-Cou expressively increased the analgesia duration (p < 0.001) by approximately 1.7−1.8 times compared to CouH or indomethacin. Thus, the results pointed out that the LDH-Cou system induced in vivo analgesic and anti-inflammatory activities and possibly uses similar mechanisms to that observed for classic NSAIDs, such as indomethacin.
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Mg-Fe layered double hydroxide intercalated with chloride (Mg-Fe-Cl LDH) was synthetized, characterized, and evaluated as adsorbent to remove nitrate from aqueous solution. The pH, initial nitrate concentration, adsorbent dosage, and particle size were investigated. Kinetic data was best represented by pseudo-second order model indicating that the rate limiting step was chemisorption. Intraparticle diffusion model indicates that adsorption kinetic is limited by external and intraparticle diffusion. Sips model was selected, based on R2, ARE, and AIC, to adequately represent the adsorption isotherms, which permits to affirm that the adsorption occurs in heterogeneous surface, obtaining the maximum adsorption capacity of 18.17 mg.g-1 at 30 oC. Thermodynamics parameters indicate that the adsorption was spontaneous, exothermic, and with structural modification. These findings come up with Mg-Fe-Cl LDH as a suitable adsorbent for nitrate and could contribute to its removal from the water and wastewater.
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Cloruros/química , Hidróxidos/química , Hierro/química , Magnesio/química , Nitratos/química , Contaminantes Químicos del Agua , Adsorción , Concentración de Iones de Hidrógeno , Cinética , Nitratos/análisisRESUMEN
Layered double hydroxides (LDHs) have emerged as promising nanomaterials for human health and although it has achieved some progress on this matter, their application within bioengineering is not fully addressed. This prompted to subject fibroblasts to two compositions of LDHs (Mg2 Al-Cl and Zn2 Al-Cl), considering an acute response. First, LDH particles are addressed by scanning electron microscopy, and no significant effect of the cell culture medium on the shape of LDHs particles is reported although it seems to adsorb some soluble proteins as proposed by energy-dispersive X-ray analysis. These LDHs release magnesium, zinc, and aluminum, but there is no cytotoxic or biocompatibility effects. The data show interference to fibroblast adhesion by driving the reorganization of actin-based cytoskeleton, preliminarily to cell cycle progression. Additionally, these molecular findings are validated by performing a functional wound-healing assay, which is accompanied by a dynamic extracellular matrix remodeling in response to the LDHs. Altogether, the results show that LDHs nanomaterials modulate cell adhesion, proliferation, and migration, delineating new advances on the biomaterial field applied in the context of soft tissue bioengineering, which must be explored in health disorders, such as wound healing in burn injuries.
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Hidróxidos , Ensayo de Materiales , Nanoestructuras , Ingeniería de Tejidos , Cicatrización de Heridas/efectos de los fármacos , Aluminio/química , Aluminio/farmacología , Animales , Matriz Extracelular/metabolismo , Hidróxidos/química , Hidróxidos/farmacología , Magnesio/química , Magnesio/farmacología , Ratones , Células 3T3 NIH , Nanoestructuras/química , Nanoestructuras/uso terapéutico , RatasRESUMEN
Although layered double hydroxides (LDH) have been listed as promising nanomaterials in human healthcare, very little has been achieved on osteoblast inflammatory signaling. Thus, osteoblasts were challenged with two LDHs (Mg2Al-Cl and Zn2Al-Cl, at 0.002 mg/mL) up to 24 h, establishing an acute inflammatory mechanism, as well as identifying whether Sonic hedgehog (Shh) signaling has an influence. Functional experiments were performed by previously treating (2 h) semiconfluent osteoblast cultures with cyclopamine molecule (cyc), a widely used Shh inhibitor. Considering inflammasome complex, the asc1 gene was significantly up-expressed in response to Zn2Al-Cl - LDHs, as well as the nrlp3 gene. By treating the osteoblast with cyc, the asc1 gene presented an even higher profile. Our results found a down-modulation of major pro-inflammatory cytokines-related genes, when tnfα and il1ß were significantly down-modulated in response to LDHs. Conversely, anti-inflammatory cytokines were up-modulated considering the same experimental procedures. Except the il6, the other il13, il10, and tgfß genes were up modulated. Additionally, Shh signaling seems to modulate this repertory as both the il13 and il10 genes were significantly up-modulated when the Shh signaling was inhibited. Altogether, our results reveal for the first time the exigency of Shh-dependent anti-inflammatory signals in LDH-induced osteoblast responses.
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Proteínas Hedgehog/metabolismo , Hidróxidos/farmacología , Mediadores de Inflamación/metabolismo , Inflamación/inmunología , Osteoblastos/inmunología , Alcaloides de Veratrum/farmacología , Diferenciación Celular , Células Cultivadas , Proteínas Hedgehog/antagonistas & inhibidores , Proteínas Hedgehog/genética , Humanos , Hidróxidos/química , Inflamación/tratamiento farmacológico , Inflamación/metabolismo , Osteoblastos/efectos de los fármacos , Osteoblastos/metabolismo , Alcaloides de Veratrum/químicaRESUMEN
Calcined hydrotalcite can be applied to remove anionic contaminants from aqueous systems such as antimony species due to its great anion exchange capacity and high surface area. Hence, this study evaluated antimonite and antimonate sorption-desorption processes onto calcined hydrotalcite in the presence of nitrate, sulfate and phosphate. Sorption and desorption experiments of antimonite and antimonate were carried out in batch equilibrium and the post-sorption solids were analyzed by X-ray fluorescence (EDXRF). Sorption data were better fitted by dual-mode Langmuir-Freundlich model (R2>0.99) and desorption data by Langmuir model. High maximum sorption capacities were found for the calcined hydrotalcite, ranging from 617 to 790meqkg-1. The competing anions strongly affected the antimony sorption. EDXRF analysis and mathematical modelling showed that sulfate and phosphate presented higher effect on antimonite and antimonate sorption, respectively. High values for sorption efficiency (SE=99%) and sorption capacity were attributed to the sorbent small particles and the large surface area. Positive hysteresis indexes and low mobilization factors (MF>3%) suggest very low desorption capacity to antimony species from LDH. These calcined hydrotalcite characteristics are desirable for sorption of antimony species from aqueous solutions.
RESUMEN
The effect of LDH samples comprised of chloride anions intercalated between positive layers of magnesium/aluminum (Mg-Al LDH) or zinc/aluminum (Zn-Al LDH) chemical composition on pre-osteoblast performance is investigated. Non-cytotoxic concentrations of both LDHs modulated pre-osteoblast adhesion by triggering cytoskeleton rearrangement dependent on recruiting of Cofilin, which is modulated by the inhibition of the Protein Phosphatase 2A (PP2A), culminating in osteoblast differentiation with a significant increase of osteogenic marker genes. The alkaline phosphatase (ALP) and bone sialoprotein (BSP) are significantly up-modulated by both LDHs; however, Mg-Al LDH nanomaterial promoted even more significance than both experimental controls, while the phosphorylations of mitogen-activated protein kinase (MAPKs)- extracellular signal-regulated kinases (ERK) and c-Jun N-terminal kinase (JNK) significantly increased. MAPK signaling is necessary to activate Runt-related transcription factor 2 (RUNX2) gene. Concomitantly, it is also investigated whether challenged osteoblasts are able to modulate osteoclastogenesis by investigating both osteoprotegerin (OPG) and Receptor activator of nuclear factor kappa-ligand (RANKL) in this model; a dynamic reprogramming of both these genes is found, suggesting LDHs in modulating osteoclastogenesis. These results suggest that LDHs interfere in bone remodeling, and they can be considered as nanomaterials in graft-based bone healing or drug-delivery materials for bone disorders.
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Sustitutos de Huesos/química , Diferenciación Celular , Hidróxidos/química , Proteínas Quinasas Activadas por Mitógenos/metabolismo , Osteogénesis , Aluminio/química , Animales , Sustitutos de Huesos/farmacología , Adhesión Celular/efectos de los fármacos , Diferenciación Celular/efectos de los fármacos , Línea Celular , Matriz Extracelular/metabolismo , Magnesio/química , Metaloproteinasas de la Matriz/genética , Metaloproteinasas de la Matriz/metabolismo , Ratones , Osteoblastos/citología , Osteoblastos/efectos de los fármacos , Osteoblastos/metabolismo , Osteogénesis/efectos de los fármacos , Osteopontina/genética , Osteopontina/metabolismo , Ligando RANK/metabolismo , Regulación hacia Arriba/efectos de los fármacos , Zinc/químicaRESUMEN
Selenate and selenite are considered emerging contaminants and pose a risk to living organisms. Since selenium anion species are at low concentration in aquatic environments, materials for its retention are required to enable monitoring. Herein, hydrotalcite was calcined and characterised to investigate sorption and desorption of selenite and selenate in competition with nitrate, sulfate and phosphate. Sorption experiments were carried out in batch system and desorption by sequential dilution. Selenite and selenate concentration remaining after N desorption steps was determined by mass balance. The isotherms were adjusted to the dual-mode Langmuir-Freundlich model (R2 > 0.99). Maximum sorption capacity ranged from 494 to 563 meq kg-1 for selenite and from 609 to 659 meq kg-1 for selenate. Sulfate and phosphate ions showed greater competitive effect on the sorption of selenate and selenite, respectively. Low mobilization factors and high sorption efficiency (MF<3%; SE ≈ 100%) indicated that calcined hydrotalcite has the wanted characteristics for retention of relevant selenium anion species in aqueous media.
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Monitoreo del Ambiente/métodos , Hidróxidos/química , Ácido Selénico/química , Ácido Selenioso/química , Absorción Fisicoquímica , Hidróxido de Aluminio/química , Magnesio/química , Hidróxido de Magnesio/química , Modelos Teóricos , Nitratos/química , Fosfatos/química , Ácido Selénico/análisis , Ácido Selénico/aislamiento & purificación , Ácido Selenioso/análisis , Ácido Selenioso/aislamiento & purificación , Compuestos de Selenio/química , Compuestos de Selenio/aislamiento & purificación , Sulfatos/química , Contaminantes del Agua/química , Contaminantes del Agua/aislamiento & purificaciónRESUMEN
Las hidrotalcitas pueden ser usadas en áreas como catálisis, medicina, química ambiental, entre otras. Dependiendo de los metales presentes, los sólidos derivados de la calcinación de hidrotalcitas también son usados debido a su carácter básico, efecto de memoria y alta área superficial especifica. En este estudio se describen algunas características de hidrotalcitas a base de Cu-Zn-Al. Los análisis se realizaron usando AAS, DRX, FTIR, TGA y DSC. En el espectro FTIR se observó que, en los sólidos con mayor cantidad de cobre, la banda del estiramiento O••H (M••OH, H••OH) se desplazó a valores más bajos de número de onda, debido a que la densidad electrónica de los grupos OH se orienta hacia el centro metálico de cobre. En todos los sólidos se observó la formación de la fase hidrotalcita, y de la fase Cu(OH)) en los sólidos con mayor contenido de cobre, lo que puede ser atribuido al efecto Jahn-Teller. Los resultados mostraron que los sólidos con mayor contenidode cobre colapsan en temperaturas menores. En todas las muestras se observaron eventos como:descomposición de la estructura HTLc, formación de óxidos metálicos y descomposición decarbonatos que quedaron ocluidos en los poros de los sólidos debido al colapso de la estructuralaminar.
Hydrotalcite-like compounds have been used in catalysis, medicine, environmental chemistry, and other applications. Depending on the metals present, the solids obtained by calcination can be used due to their basicity, memory effect, and high specific surface area. This study describes some characteristics of hydrotalcites based on Cu-Zn-Al. The solids were characterized by AAS, XRD, FTIR, DSC and TGA. In the FTIR spectra it was observed that in the solids with higher copper contents the band signed to O••H stretching (M••OH, H••OH) was moved to lower wave number values, because electron density of hydroxide groups orients toward the metallic copper center. In all materials hydrotalcite phase formation was observed and the Cu(OH)) phase in solids with higher copper content was detected, fact attributed to the Jahn-Teller effect. Results indicate that the collapse of the structure occurs at lower temperatures in the case of solids with higher copper content. In all the tested materials the decomposition of the HTLc structure and the formation ofmetal oxides was observed, as well as decomposition of carbonate ions occluded in the solid dueto the collapse of the lamellar structure.
Os compostos do tipo hidrotalcita podem ser usados nas áreas de catalise, medicina, química ambiental, entre outras. Dependendo dos metais presentes, os sólidos obtidos pela calcinação de hidrotalcitas também podem ser usados devido a propriedades tais como: caráter básico, efeito de memória e elevada área superficial especifica. Neste estudo descrevem-se algumas características das hidrotalcitas baseadas em Cu-Zn-Al. Na caracterização dos sólidos usaram-se astécnicas AAS, DRX, FTIR, TGA e DSC. Observou-se nos sólidos com maior conteúdo de cobre que o estiramento O••H (M••OH, H••OH) se desloca a valores menores de numero de onda, devido a que a densidade eletrônica dos grupos hidróxido se orienta em direção ao centro metálico de cobre. Em todos os materiais observou-se a fase hidrotalcita e nos sólidos com maior conteúdo de cobre foi detectada a fase Cu(OH)), fato atribuído ao efeito Jahn-Teller. Os resultados indicam que o colapso da estrutura acontece em temperaturas menores no caso dos sólidos com maior conteúdo de cobre. Em todos os materiais observaram-se decomposição da estrutura HTLc, formação de óxidosúmetálicos, e a decomposição dos íons carbonato que ficaram ocluídos nos sólidos devido ao colapsoda estrutura lamelar.
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This work presents two easy ways for preparing nanostructured mesoporous composites by interconnecting and combining SBA-15 with mixed oxides derived from a calcined Mg-Al hydrotalcite. Two different Mg-Al hydrotalcite addition procedures were implemented, either after or during the SBA-15 synthesis (in situ method). The first procedure, i.e., the post-synthesis method, produces a composite material with Mg-Al mixed oxides homogeneously dispersed on the SBA-15 nanoporous surface. The resulting composites present textural properties similar to the SBA-15. On the other hand, with the second procedure (in situ method), Mg and Al mixed oxides occur on the porous composite, which displays a cauliflower morphology. This is an important microporosity contribution and micro and mesoporous surfaces coexist in almost the same proportion. Furthermore, the nanostructured mesoporous composites present an extraordinary water vapor sorption capacity. Such composites might be utilized as as acid-base catalysts, adsorbents, sensors or storage nanomaterials.
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Sorption of aspartic and glutamic aminoacids by regeneration of calcined hydrotalcite is reported. Hydrotalcite was synthesized by coprecipitation and calcined at 773 K. Sorption experiments were performed at 298 K and 310 K, and the results reveal that at low aminoacids equilibrium concentrations, intercalation of hydroxyl anions takes place while at high equilibrium concentrations, the sorption process occur by means re-hydration and aminoacids intercalation of hydrotalcite. The results also suggested that Asp and Glu sorption is a temperature dependent process. The amount of sorbed amino acid decreases as the temperature increase. The effect is more pronounced for Glu sorption probably due to its higher hydrophobic character, which makes the sorption more difficult in comparison with sorption of Asp at higher temperature.
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Dos nuevos materiales tipo hidrotalcita, basados en NiCoCr y NiCoFe, se obtuvieron por el método hidrotérmico. Estos materiales se modificaron con especies de vanadio por intercambio iónico. Los sólidos se caracterizaron usando difracción de rayos X (DRX), análisis elemental (absorción atómica), y análisis termogravimétrico (ATG). Los sólidos con y sin intercambio se trataron térmicamente para obtener los respectivos óxidos mixtos, que posteriormente se evaluaron en la reacción de deshidrogenaciónoxidativa de propano (Dhop) a una velocidad espacial de 50 mL/min g y en un rango de temperatura comprendido entre 250 y 500 °C. Los estudios catalíticos mostraron un efecto positivo al incorporar el vanadio para el material NiCoCr, mientras que para el sistema NiCoFe modificado se observó una disminución en su actividad catalítica.
Two novel hydrotalcite-like materials have been synthesized by hydrothermal treatment. Using ionic exchange method, the materials have been modified with vanadium species. Characterization of the materials was carried out by X-Ray diffraction (XRD), chemical analyses (atomic absorption), and Thermogravimetric analyses (TGA). Modified and non-modified materials have been calcined in order to obtain respective mixed oxides, which were tested in oxidative dehydrogenation of propane (ODHP) at a space velocity of 50 mL/min g with a temperature range between 250-500 °C. The catalytic studies showed a positive effect by incorporating vanadium for NiCoCr system, while for the NiCoFe modified system a decrease in catalytic activity was shown.
Dois novos materiais tipo hidrotalcita baseados em NiCoCr e NiCoFe obtiveram-se pelo método hidrotérmico. Esses materiais foram modificados com espécies de vanádio por troca iô nica. Os materiais caracterizaram-se usando difração de raios X (DRX), análise elementar (absorçãoatômica) e análisetermogravimétrica (ATG). Os sólidos com e sem troca foram tratados termicamente para obter os respectivos óxidos mistos, que posteriormente se avaliaram na reação de desidrogenaçãooxidativa de propano (DHOP) a uma velocidade espacial de 50 mL/min g e em uma faixa de temperatura entre 250 a 500 °C. Os estudos catalíticos mostraram um efeito positivo ao incorporar o vanádio para o material NiCoCr, enquanto para o sistema NiCoFe modificado foi observada uma diminuiçãona sua atividade catalítica.