RESUMO
In this study, a facile method for the synthesis of leach proof and earth-abundant non-noble Ni nanoparticles on N-doped carbon nanotubes is reported. The catalyst was synthesized by an impregnation-carbonization method, wherein a Ni-chitosan complex upon carbonization in a 5% H2/N2 atmosphere at 800 °C yielded Ni-containing N-doped CNTs. Chitosan served as a single source of carbon and nitrogen, and the nanotube growth was facilitated by the in situ formed Ni nanoparticles. The nanocatalyst was thoroughly characterized by several techniques; elemental mapping by SEM and TEM analysis confirmed the uniform distribution of Ni nanoparticles on the surface of N-doped CNTs with an average size in the range of 10-15 nm. The catalyst efficiently reduced a variety of nitroarenes (>99%) into their corresponding amines at a moderate pressure (5 bar) and a comparatively lower temperature (80 °C). Furthermore, the easy recovery of the catalyst using an external magnetic field along with high activity and easy recyclability makes the protocol eco-friendly.
Assuntos
Aminas/síntese química , Quitosana/química , Complexos de Coordenação/química , Nanopartículas Metálicas/química , Nanotubos de Carbono/química , Nitrobenzenos/química , Aminas/química , Complexos de Coordenação/síntese química , Hidrogênio/química , Hidrogenação , Estrutura Molecular , Níquel/química , Tamanho da Partícula , Propriedades de SuperfícieRESUMO
The present study demonstrates the BiVO4 nanoparticles synthesized by co-precipitation (CPM), hydrothermal (HTM) and solution combustion method (SCM) and their visible light photocatalytic activity under irradiation of green light emitting diodes. The synthesized catalysts were characterized by Powder X-ray Diffraction, UV-vis Diffuse reflectance spectroscopy, BET Surface area analysis, Fourier Transform Infrared spectroscopy and Scanning electron microscopy. Result demonstrated that the photocatalytic activity of BiVO4 catalyst synthesized by solution combustion method has 4.7, 1.9 and 6.7 times higher photocatalytic activity under irradiation of green light emitting diodes as compared to ultraviolet, blue and red light emitting diodes respectively. It has also been found that the photocatalytic activity of the synthesized BiVO4 by SCM is 6.5 times more as compared to commercial TiO2 under green light emitting diodes irradiation. Furthermore, the room temperature fluorescence and quenching analysis was carried out for the determination of hydroxyl radical generation and understanding photocatalytic activity of the catalyst under green light emitting diodes irradiation. Additionally, the effect of operational parameters under irradiation of green light emitting diodes was studied to optimize catalyst amount, pH, initial dye concentration and amount of H2O2. Recyclability study concern about solution combustion synthesized BiVO4 catalyst has also been done up to 5 cycles in presence of green light emitting diodes irradiation.
RESUMO
Herein we report a low cost and eco-friendly approach for the recovery of metals from cathode and anode materials of mobile phone spent lithium-ion batteries (LIBs). Li-based metal oxide and graphite were efficiently separated from their respective foils and used for lixiviation. Acetic acid (CH3COOH) and water were used as lixiviants for the recovery of metals from cathode and anode materials respectively. It was found that with 3â¯M Acetic acid and 7.5â¯vol% H2O2 as reducing agent 99.9% Li, 98.7% Co, and 99.5% Mn were leached out from cathode material in 40â¯min at 70⯰C and a pulp density of 20â¯g/L. Besides the cathode leaching, Li was also extracted from anodic material graphite using water as a solvent and further recovered as solid Li2CO3 (99.7% Li). The kinetic evaluation of the cathode lixiviate process was studied using three different shrinking-core kinetic Models and established that the reaction follows the product layer diffusion controlled mechanism. From the cathode leach liquor, 99% Co was recovered as metal sulfide by controlled sulfide precipitation with 99.2% purity, and subsequently, MnCO3 and Li2CO3 were obtained with the purity of 98.7% and 99.4%, respectively. The purity of the salts revealed that these products recovered from spent LIBs might be utilized in the electrochemical energy-storage applications. In addition, this recycling process would promote the sustainable development of the battery industry.
Assuntos
Fontes de Energia Elétrica , Reciclagem , Eletrodos , Resíduo Eletrônico , Peróxido de Hidrogênio , LítioRESUMO
The problem of textile dye pollution has been addressed by various methods, mainly physical, chemical, biological, and acoustical. These methods mainly separate and/or remove the dye present in water. Recently, advanced oxidation processes (AOP) have been focused for removal of dye from waste water due to their advantages such as ecofriendly, economic and capable to degrade many dyes or organic pollutant present in water. Photocatalysis is one of the advance oxidation processes, mainly carried out under irradiation of light and suitable photocatalytic materials. The photocatalytic activity of the photocatalytic materials mainly depends on the band gap, surface area, and generation of electron-hole pair for degradation dyes present in water. It has been observed that the surface area plays a major role in photocatalytic degradation of dyes, by providing higher surface area, which leads to the higher adsorption of dye molecule on the surface of photocatalyst and enhances the photocatalytic activity. This present review discusses the synergic effect of adsorption of dyes on the photocatalytic efficiency of various nanostructured high surface area photocatalysts. In addition, it also provides the properties of the water polluting dyes, their mechanism and various photocatalytic materials; and their morphology used for the dye degradation under irradiation of light along with the future prospects of highly adsorptive photocatalytic material and their application in photocatalytic removal of dye from waste water.
Assuntos
Compostos Azo/análise , Corantes/análise , Eliminação de Resíduos Líquidos/métodos , Águas Residuárias/química , Poluentes Químicos da Água/análise , Adsorção , Compostos Azo/química , Catálise , Corantes/química , Nanoestruturas , Oxirredução , Processos Fotoquímicos , Poluentes Químicos da Água/químicaRESUMO
A facile way of recovering 3d transition metals of industrial importance from spent lithium-ion batteries (LIBs) without using any surfactants has been developed. Mn- and Co-rich spent LIBs were chosen as sustainable sources for recovering the oxides of the respective elements. The physical dismantling of Li-ion batteries, chemical leaching with 2 M acetic acid, precipitation with ammonium carbonate, hydrothermal conditioning and calcination at 650 °C led to the facile formation of spherical spinel MnCo2O4 with very high morphological selectivity. The obtained spherical MnCo2O4 was identified by various advanced characterization techniques. Detailed electrochemical characterization revealed that the recovered spheres of spinel MnCo2O4 were effective in catalyzing the oxygen evolution reaction (OER) in 1 M KOH and required an overpotential of 358 and 400 mV to generate a current density of 5 and 10 mA cm-2, respectively, with a relatively low catalyst loading (0.001025 g cm-2). Comparative electrocatalytic studies carried out with recovered LiCoO2, recovered LiXMnOX+1 and commercially available catalysts such as RuO2 (c-RuO2), Co3O4 (c-Co3O4) and MnO2 (c-MnO2) revealed that the recovered spheres of spinel MnCo2O4 were more effective OER catalysts than the recovered LiCoO2, recovered LiXMnOX+1, c-Co3O4 and c-MnO2 and exhibited comparable activity to that of c-RuO2 with very little difference in overpotential (â¼50 mV) at current densities of 5 and 10 mA cm-2. With such a low catalyst loading, the observed electrocatalytic performance in water oxidation of a material recovered from waste is highly significant and will surely attain greater industrial importance when the recycling of spent LIBs from electronic wastes is considered.
RESUMO
The separation of fine spent sorbents from treated water after remediation is a major difficulty associated with phosphate wastewater treatment technology. In this study, a novel aluminium-pillared acid activated bentonite powder (Al-ABn) and alginate immobilized aluminium-pillared acid activated bentonite beads (Al-ABn-AB) were synthesized and used for the removal of aqueous phosphate. The phosphate removal behaviour of adsorbents were evaluated by batch experiments as a function of various parameters such as pH, initial concentration, contact time, temperature, adsorbent dose and presence of coexisting ions. The sorption isotherm studies by Langmuir model showed 12.87 and 11.11 mgP/g maximum phosphate uptake capacity for Al-ABn and Al-ABn-AB, respectively. The kinetic studies confirm that the adsorption of phosphate by Al-ABn and Al-ABn-AB follows a pseudo-second-order model. The feasibility of Al-ABn-AB was also assessed in continuous mode in fixed bed column and the loading capacity obtained was 4.55mg/g. The adsorption capacity of Al-ABn-AB beads remained at relatively high even after four regeneration cycles. Furthermore, the applicability of the synthesized adsorbents towards real municipal wastewater confirmed that novel synthesized Al-ABn and Al-ABn-AB are the promising adsorbents for the removal of phosphate from contaminated water.
Assuntos
Alumínio/química , Bentonita/química , Eliminação de Resíduos Líquidos/métodos , Poluentes Químicos da Água/química , Adsorção , Alginatos , Ácido Glucurônico , Ácidos HexurônicosRESUMO
A series of self-supported chiral polymeric MnIII N,N'-ethylenebis(salicylimine) (salen) complexes were synthesized through metalation of the corresponding salen ligands obtained by condensation of several bis/tris-aldehydes with (1R,2R)-1,2-diaminocyclohexane. Upon employment in the asymmetric epoxidation reaction of nonfunctionalized olefins, all complexes showed enhanced activity and enantioselectivity relative to the classical Jacobsen's monomeric salen complex. However, 1,3,5-triazole-based polymeric MnIII salen complexâ 7 was noticeably preferred over others owing to its ability to render higher enantioselectivity at the expense of lower catalyst loading. Furthermore, complexâ 7 was recycled and reused in eight recycling experiments with marginal loss in catalytic activity.
RESUMO
The present manuscript focus on the synthesis of surface hydroxyl group enriched titanium dioxide nanotube (TNT) by hydrothermal method for preferential adsorption of methylene blue (MB) dye. The mixture of methylene blue (MB) and rhodamine B (RhB) dye was used to study the preferential adsorption nature of TNT. The synthesized TNT were characterized by various techniques such as powder X-ray diffraction (PXRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), N2 adsorption, and ammonia-temperature programmed desorption (NH3-TPD) analysis. Result demonstrated that enhancement in the surface area of TNT and higher number of hydroxyl group on the surface of TNT. In the binary mixture, the adsorption of MB dye was 12.9 times higher as compared to RhB dye, which clearly indicated the preferential adsorption of MB dye on TNT surface. The preferential interaction of MB on TNT is due to the electrostatic interaction between the cationic MB and negatively charged TNT surface. The preferential adsorption of MB dye was studied by applying Langmuir, Freundlich and Sips isotherm; pseudo-first and second-order kinetic model. Furthermore, the regeneration of dye adsorbed TNT was carried out by eco-friendly photocatalytic process under the irradiation of ultraviolet light.
RESUMO
This work reports intercalation of a sparingly soluble antibiotic (ciprofloxacin) into layered nanostructure silicate, montmorillonite (MMT) and its reaction with bone derived polypeptide, gelatin that yields three-dimensional composite hydrogel. Drug intercalation results in changes in MMT layered space and drug loaded MMT and gelatin creates 3D morphology with biodegradable composite hydrogels. These changes can be correlated with electrostatic interactions between the drug, MMT and the gelatin polypeptides as confirmed by X-ray diffraction patterns, thermal, spectroscopic analyses, computational modeling and 3D morphology revealed by SEM and TEM analysis. No significant changes in structural and functional properties of drug was found after intercalation in MMT layers and composite hydrogels. In vitro drug release profiles showed controlled release up to 150h. The drug loaded composite hydrogels were tested on lung cancer cells (A549) by MTT assay. The results of in vitro cell migration and proliferation assay were promising as composite hydrogels induced wound healing progression. In vitro biodegradation was studied using proteolytic enzymes (lysozyme and protease K) at physiological conditions. This new approach of drug intercalation into the layered nanostructure silicate by ion-exchange may have significant applications in cost-effective wound dressing biomaterial with antimicrobial property.
Assuntos
Antibacterianos/administração & dosagem , Bandagens , Bentonita/administração & dosagem , Materiais Biocompatíveis , Ciprofloxacina/administração & dosagem , Sistemas de Liberação de Medicamentos , Gelatina/administração & dosagem , Hidrogéis , Ferimentos e Lesões/terapia , Linhagem Celular Tumoral , Humanos , Microscopia Eletrônica de Varredura , Microscopia Eletrônica de Transmissão , Difração de Pó , Espectroscopia de Infravermelho com Transformada de FourierRESUMO
Cu(ii) Schiff base complexes Cu(ii)- and Cu(ii)- based on 2-acetyl pyridine with both (1R,2R)-1,2-diaminocyclohexane and (1S,2S)-1,2-diaminocyclohexane were synthesized in a single step. Subsequent reduction of ligands and with NaBH4 followed by complexation with Cu(OTf)2 resulted in generation of two more additional chiral centers in complexes Cu(ii)- and Cu(ii)-. The ligands and their corresponding complexes were well characterized by several spectral techniques like (1)H-NMR, (13)C-NMR, LC-MS, CD, UV-Vis spectroscopy and microanalysis. The respective Cu(ii) complexes derived from ligands and were investigated using both the solution and solid state EPR spectra. The particular orientation of the reduced complex with Cu(OTf)2 was confirmed by the X-ray crystal structure of the corresponding complex. All the catalytic protocols were applied in the asymmetric aza-Henry reaction to evaluate the catalytic properties of the Cu(ii) complexes in the present study.
RESUMO
Chiral sulfinamide based organocatalyst 11 was synthesized from readily available starting materials and used for the asymmetric ring-opening (ARO) reaction of meso epoxides with anilines. A high yield (up to 95%) of chiral ß-amino alcohols with excellent enantioselectivity (ee up to 99%) was achieved in 24-30 h at rt under optimized reaction conditions. A probable mechanism for the catalytic ARO reaction is envisaged by (1)H and (13)C NMR experiments.
RESUMO
A chiral oxazoline-based organocatalyst has been found to efficiently catalyze asymmetric Strecker reactions of various aromatic and aliphatic N-benzhydrylimines with trimethylsilyl cyanide (TMSCN) as a cyanide source at -20 °C to give α-aminonitriles in high yield (96 %) with excellent chiral induction (up to 98 %â ee). DFT calculations have been performed to rationalize the enantioselective formation of the product with the organocatalyst in these reactions. The organocatalyst has been characterized by single-crystal X-ray diffraction analysis, as well as by other analytical methods. This protocol has been extended to the synthesis of the pharmaceutically important drug molecule levamisole in high yield and with high enantioselectivity.
Assuntos
Compostos Benzidrílicos/química , Cianetos/química , Iminas/química , Levamisol/síntese química , Nitrilas/química , Oxazóis/química , Compostos de Trimetilsilil/química , Catálise , Levamisol/química , Estrutura Molecular , Teoria Quântica , Estereoisomerismo , Difração de Raios XRESUMO
Intercalation of 6-mercaptopurine (6-MP), an antineoplastic drug in interlayer gallery of Na(+)-clay (MMT) was further entrapped in poly (L-lactide) matrix to form microcomposite spheres (MPs) in order to reduce the cell toxicity and enhance in vitro release and pharmacokinetic proficiency. The drug-clay hybrid was fabricated via intercalation by ion-exchange method to form MPs from hybrid. In vitro drug release showed controlled pattern, fitted to kinetic models suggested controlled exchange and partial diffusion through swollen matrix of clay inter layered gallery. The in vitro efficacy of formulated composites drug was tested in Human neuroblastoma cell line (IMR32) by various cell cytotoxic and oxidative stress marker indices. In vivo pharmacokinetics suggested that the intensity of formulated drug level in plasma was within remedial borders as compared to free drug. These clay based composites therefore have great potential of becoming a new dosage form of 6-MP.
Assuntos
Silicatos de Alumínio/química , Antineoplásicos/administração & dosagem , Antineoplásicos/farmacocinética , Portadores de Fármacos/química , Mercaptopurina/administração & dosagem , Mercaptopurina/farmacocinética , Poliésteres/química , Animais , Antineoplásicos/sangue , Bentonita/química , Linhagem Celular Tumoral , Sobrevivência Celular/efeitos dos fármacos , Química Farmacêutica , Argila , Formas de Dosagem , Feminino , Humanos , Peroxidação de Lipídeos/efeitos dos fármacos , Mercaptopurina/sangue , Microscopia Eletrônica de Varredura , Microesferas , Estresse Oxidativo/efeitos dos fármacos , Ratos , Ratos Wistar , Espectroscopia de Infravermelho com Transformada de Fourier , Difração de Raios XRESUMO
Chiral polymeric Co(III) salen complexes with chiral ((R)/(S)-BINOL, diethyl tartrate) and achiral (piperazine and trigol) linkers with varying stereogenic centers were synthesized for the first time and used as catalysts for aminolytic kinetic resolution (AKR) of a variety of terminal epoxides and glycidyl ethers to get enantio-pure epoxides (ee, 99%) and N-protected ß-amino alcohols (ee, 99%) with quantitative yield in 16 h at RT under optimized reaction conditions. This protocol was also used for the synthesis of two enantiomerically pure drug molecules (R)-Naftopidil (α1-blocker) and (S)-Propranolol (ß-blocker) as a key step via AKR of single racemic naphthylglycidyl ether with Boc-protected isoproylamine with 100% epoxide utilization at 1 g level. The catalyst 1 was successfully recycled for a number of times.
Assuntos
Cobalto/química , Compostos de Epóxi/química , Etilenodiaminas/química , Naftalenos/síntese química , Compostos Organometálicos/química , Piperazinas/síntese química , Propranolol/síntese química , Cinética , Estrutura Molecular , Naftalenos/química , Compostos Organometálicos/síntese química , Piperazinas/química , Propranolol/química , EstereoisomerismoRESUMO
A phenylalanine derived chiral amide is developed that serves as an effective organocatalyst for the reaction of allyltrichlorosilane with aryl, hetero-aryl and α,ß-unsaturated aldehydes to afford the desired homoallylic alcohols in good yield (up to 90%) and high enantioselectivity (up to 99%). The experimental results and DFT calculations suggest that para substituted aromatic aldehydes as substrate show higher ee in the product than their ortho/meta counterparts. The (1)H and (13)C NMR spectra study corroborated the calculated results. The chiral organocatalyst can be easily synthesized from optically pure phenylalanine in two simple steps with 90% overall yield.
Assuntos
Aldeídos/química , Amidas/química , Aminoácidos/química , Simulação por Computador , Compostos de Tosil/química , Catálise , Estrutura Molecular , Compostos Orgânicos/química , EstereoisomerismoRESUMO
The organized mesoporous matrices with large surface area and large pore volumes are potential drug carriers and hence find good applications in the field of controlled and sustained drug delivery. Two novel mesoporous synthetic hectorite (MSH) materials, namely, MSH3 and MSH4 with diverse composition and pore performance have been synthesized by a template free route and studied for the controlled drug delivery applications. MSH3 with 0.14LiF:5.93Mg(OH)2:8 SiO2 synthetic composition exhibited higher quinine adsorption than that by MSH4 (2.8LiF:4.6Mg(OH)2:8SiO2). In vitro studies at 37±0.5°C temperature under sequential buffer conditions showed controlled drug release with respect to the variation in pH values while following Eudragit VR L100 coated gelatin capsules; however, dialysis bag technique do not show such pH controlled delivery. Kinetic data suggest the release of QUI from the nanocomposite follows dissolution diffusion model.
Assuntos
Sistemas de Liberação de Medicamentos , Silicatos/química , Adsorção , Antimaláricos/química , Concentração de Íons de Hidrogênio , Microscopia Eletrônica de Varredura , Nanocompostos/química , Nanocompostos/ultraestrutura , Porosidade , Quinina/química , Espectroscopia de Infravermelho com Transformada de Fourier , Termogravimetria , Difração de Raios XRESUMO
We are reporting the synthesis, characterization, and calf thymus DNA binding studies of novel chiral macrocyclic Mn(III) salen complexes S-1, R-1, S-2, and R-2. These chiral complexes showed ability to bind with DNA, where complex S-1 exhibits the highest DNA binding constant 1.20 × 10(6) M(-1). All the compounds were screened for superoxide and hydroxyl radical scavenging activities; among them, complex S-1 exhibited significant activity with IC(50) 1.36 and 2.37 µM, respectively. Further, comet assay was used to evaluate the DNA damage protection in white blood cells against the reactive oxygen species wherein complex S-1 was found effective in protecting the hydroxyl radicals mediated plasmid and white blood cells DNA damage.
Assuntos
Dano ao DNA , DNA/genética , DNA/metabolismo , Etilenodiaminas/química , Etilenodiaminas/farmacologia , Compostos Macrocíclicos/química , Compostos Organometálicos/química , Compostos Organometálicos/farmacologia , Animais , Bovinos , DNA/química , Etilenodiaminas/síntese química , Etilenodiaminas/metabolismo , Sequestradores de Radicais Livres/síntese química , Sequestradores de Radicais Livres/química , Sequestradores de Radicais Livres/metabolismo , Sequestradores de Radicais Livres/farmacologia , Radical Hidroxila/química , Concentração Inibidora 50 , Desnaturação de Ácido Nucleico/efeitos dos fármacos , Compostos Organometálicos/síntese química , Compostos Organometálicos/metabolismo , Estereoisomerismo , Superóxidos/química , Temperatura de Transição/efeitos dos fármacosRESUMO
A first approach for catalytic asymmetric Strecker reaction of aldehydes with a secondary amine in the presence of sodium fluoride using hydroquinine as chiral catalyst was developed. The catalytic system gave α-aminonitriles in excellent yields (up to 95%) and high enantioselectivities (er up to 94:6). The efficacy of the chiral product was successfully fulfilled in the improved synthesis of (S)-clopidogrel (an antiplatelet agent).
Assuntos
Aldeídos/química , Aminas/química , Inibidores da Agregação Plaquetária/síntese química , Quinidina/análogos & derivados , Ticlopidina/análogos & derivados , Catálise , Clopidogrel , Espectroscopia de Ressonância Magnética , Estrutura Molecular , Quinidina/química , Fluoreto de Sódio/química , Estereoisomerismo , Ticlopidina/síntese químicaRESUMO
Using metallic copper as reductant and tetrachloroethylene as carbon precursor, a simple, low temperature solvothermal method for the synthesis of horn shaped carbon nanotubes is reported. The detail study of reaction parameters such as temperature, time, carbon precursor amount, type and catalyst proportion has been carried out to optimize the conditions wherein that the copper metal (10 g) mediated reduction of tetrachloroethylene (25 mL) at 200°C for 5h resulted in the horn shaped carbon nanotubes with high yield and structural selectivity. The adsorption properties of horn shaped carbon nanotubes were investigated for carbon dioxide, methane, carbon monoxide and nitrogen as adsorbate by volumetric measurements up to 850 mm Hg. The prepared horn shaped carbon nanotubes showed good adsorption capacity for CO(2) (45 cm(3)/g) and CO (17 cm(3)/g), at 303 K and 850 mm Hg pressure, with high equilibrium selectivity (73.3 for CO(2) and 110.7 for CO at 318 K) and capacity selectivity (9.1 for CO(2) and 3.1 for CO at 850 mm Hg and 318 K) over nitrogen which provides the tool for the separation of CO(2) from its mixture with nitrogen observed in flue gas of thermal power plants and boilers, as well as with CO such as syngas.
Assuntos
Poluentes Atmosféricos/química , Nanotubos de Carbono/química , Adsorção , Dióxido de Carbono/química , Monóxido de Carbono/química , Cloro/química , Cobre/química , Metano/química , Microscopia Eletrônica de Varredura , Microscopia Eletrônica de Transmissão , Nanotubos de Carbono/ultraestrutura , Nitrogênio/química , Reciclagem/métodos , Tetracloroetileno/químicaRESUMO
Recyclable chiral amide-based organocatalyst 5 efficiently catalyzed asymmetric Strecker reaction of various aromatic and aliphatic N-benzhydrylimines with ethyl cyanoformate as cyanide source at -10 °C to give a high yield (95%) of α-aminonitriles with excellent chiral induction (ee, up to 99%) with the added advantage of recyclability. Based on experimental observations a probable mechanism was proposed for this reaction. This protocol with catalyst 5 was extended for the synthesis of (R)-phenylalanine and pharmaceutically important drug intermediate (R)-3-phenylpropane-1,2-diamine in high yield with high enantioselectivity.