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1.
AAPS PharmSciTech ; 20(6): 248, 2019 Jul 08.
Artigo em Inglês | MEDLINE | ID: mdl-31286298

RESUMO

Anti-caries activity of fluoride ions is due to the protection against demineralization and the enhancement of remineralization of tooth enamel. Dentifrices available on the market contain sodium fluoride, sodium monofluorophosphate, stannous fluoride, and amine fluoride as source of these ions. A new compound working both as fluoride ion source and as abrasive was projected. Hybrids based on F- ions intercalated between the lamellae of hydrotalcite-like compounds (HTlc-F), namely MgAl-HTlc-F and ZnAl-HTlc-F, were prepared and characterized. Then, three different percentages (2, 3, and 4%) of both HTlc-F compounds were assayed. After the rheological characterization, the dentifrices containing 3 and 4% of MgAl-HTlc-F and ZnAl-HTlc-F, respectively, resulted to be the most suitable ones. Two novel in vitro methods, "rotary toothbrush method" and "manual brushing method," were developed and used in order to study the F- ions release from the prepared dentifrices. The obtained results showed that the dentifrice containing ZnAl-HTlc-F (4%) was the most effective in releasing fluoride ions. The "rotary toothbrush method" resulted to be the most suitable as the simulation of the brushing movements is standardizable and reproducible.


Assuntos
Hidróxido de Alumínio/química , Dentifrícios/química , Fluoretos/química , Hidróxido de Magnésio/química , Fosfatos/química , Remineralização Dentária , Esmalte Dentário , Técnicas In Vitro
2.
J Oleo Sci ; 68(7): 679-687, 2019 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-31178468

RESUMO

Hydrotalcite or Mg-Al LDHs were synthesized by co-precipitation method. The Mg-Al mixed oxide was then derived by calcination of hydrotalcite at 450°C. The metal modified catalysts (Mo/Mg-Al and V/Mg-Al) were prepared by incipient wetness impregnation method. The obtained catalysts were characterized by several useful techniques and tested the reactivity for dehydrogenation and oxidative dehydrogenation of ethanol (gas-phase) to produce acetaldehyde. The catalytic reactions were performed at temperature range from 200 to 400°C for both non-oxidative and oxidative atmospheres. The results showed that the vanadium-modified hydrotalcite (V/Mg-Al) exhibited the highest ethanol conversion (34.3%) and acetaldehyde yield (15.5%) at 400℃ in the non-oxidative atmosphere. For the oxidative dehydrogenation of ethanol, the V/Mg-Al catalyst showed the highest activity at 400°C giving the ethanol conversion and acetaldehyde yield of 73.7% and 29.5%, respectively. This result probably related to the highest base density of V/Mg-Al catalyst (6.13 µmol CO2/m2) measured by CO2-TPD. The catalytic activity of Mg-Al catalyst and metal modified catalyst slightly decreased upon time-on-stream test for 10 h on oxidative dehydrogenation of ethanol due to carbon deposition.


Assuntos
Compostos de Alumínio/química , Hidróxido de Alumínio/química , Etanol/química , Compostos de Magnésio/química , Hidróxido de Magnésio/química , Molibdênio/química , Vanádio/química , Compostos de Alumínio/síntese química , Hidróxido de Alumínio/síntese química , Carbono , Catálise , Precipitação Química , Temperatura Alta , Hidrogenação , Compostos de Magnésio/síntese química , Hidróxido de Magnésio/síntese química , Oxirredução
3.
Inorg Chem ; 58(13): 8369-8378, 2019 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-31247863

RESUMO

This article reports the effect of Gd(III) doping on the structure, microstructure, and optical properties of boehmite nanoparticles. The bright-blue fluorescence along with a long lifetime makes our material an efficient candidate for optical applications. Our material particularly targets and eliminates hexavalent chromium ions (Cr(VI)) from aqueous media, which turns it into a multifunctional fluorescent nanosensor (MFNS). The development of an efficient hexavalent chromium ion (Cr(VI)) sensor to detect and quantify Cr(VI) ions is still a serious issue worldwide. Thus, this work will be very beneficial for various environmental applications. No such work has been reported so far which includes cost-effective and biocompatible boehmite nanoparticles in this field. Detailed synthesis and characterization procedures for the MFNS have been incorporated here. The biocompatibility of the MFNS has also been studied rigorously by performing cell survivability assay (MTT) and cellular morphology assessments. Our extensive research confirmed that the "turn-off" sensing mechanism of this sensor material is based on a collisional quenching model which initiates the photoinduced electron transfer (PET) process. High selectivity and sensitivity (∼1.05 × 10-5 M) of the MFNS toward hexavalent chromium ions even in real life wastewater samples have been confirmed, which makes this fluorescent probe a potential candidate for new age imaging and sensing technologies.


Assuntos
Hidróxido de Alumínio/química , Óxido de Alumínio/química , Cromo/análise , Corantes Fluorescentes/química , Nanopartículas/química , Águas Residuárias/análise , Adsorção , Hidróxido de Alumínio/síntese química , Óxido de Alumínio/síntese química , Linhagem Celular Tumoral , Fluorescência , Corantes Fluorescentes/síntese química , Gadolínio/química , Humanos , Limite de Detecção , Microscopia de Fluorescência/métodos , Porosidade , Espectrometria de Fluorescência/métodos
4.
Chemosphere ; 230: 76-83, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31102874

RESUMO

The coagulation mechanism for removing particles by Al13 has been extensively investigated for water treatments. It was widely accepted that Al13 played important roles in coagulation mainly by charge neutralization and electrostatic patch. However, the discovery of Al13 aggregates (Al13agg) in flocs indicated that the real coagulation process should be different from the previous understanding, including when Al13agg were generated and how it interacted with negative particles. The aggregation process of Al13 during coagulation and its micro-interfacial effect on particle coagulation remains to be explored. In this study, to investigate the aggregation of Al13 and its effect on coagulation performance, two parallel coagulation jar tests were conducted on silica suspensions by preformed Al13agg and Al13, respectively. The results showed that optimized coagulation for particle removal by Al13 occurred from pH 7 to pH 9, which was dominated by the in-situ aggregation of Al13. The results confirmed that Al13agg were both present in flocs generated in two tests, however, the morphology and distribution of surface Al of flocs were different for two tests. The in-situ formed Al13agg covered all over the silica particles in flocs, resulting in compact structure with rough surfaces, while the preformed Al13agg mainly distributed on joint sites between particles, generating denser flocs with smooth surfaces. This difference verified that the in-situ aggregation of Al13 was the key factor to optimized particle coagulation. The overall optimized particle coagulation by Al13 should undergo the following pathway: charge neutralization - in-situ aggregation of Al13 - inter-particle bridging.


Assuntos
Alumínio/química , Dióxido de Silício/química , Purificação da Água/métodos , Hidróxido de Alumínio/química , Floculação , Concentração de Íons de Hidrogênio , Polímeros/química
5.
J Environ Sci (China) ; 81: 168-180, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-30975319

RESUMO

The applications of natural polymeric flocculants due to their green feature has been recently received much more attention. In this work, the combined usages of a cationic starch-based coagulant and polyaluminum chloride (PACl) were extensively evaluated for various addition sequences in the coagulation of both raw (surface water from the Jiuxiang River) and synthetic turbid water (two kaolin suspensions with different initial turbidities). Two typical cationic starch-based coagulants with different structures (St-G and St-E) were tried. In comparison to St-G, St-E and PACl used individually as well as St-G and St-E dosed after PACl, the combination of the starch-based coagulants fed before PACl showed higher turbidity removal efficiency, which featured not only less optimal doses of both inorganic and organic coagulants but also lower residual turbidity. On the basis of a detailed analysis of the particle size and its distribution in solution supernatants before and after coagulation by two starch-based coagulants and PACl, polymeric coagulants preferentially coagulate the small-sized colloids due to their distinct long-chain structures, but PACl preferentially coagulates the medium-sized ones. Thus, the medium-sized particles that were previously formed by the starch-based coagulants would be collectively and effectively removed by the subsequent addition of PACl. The addition sequence of the inorganic and organic coagulants in their combined usage is an important factor for improvement of the turbidity removal efficiency in practice.


Assuntos
Hidróxido de Alumínio/química , Poluentes Químicos da Água/química , Cor , Floculação , Modelos Químicos , Eliminação de Resíduos Líquidos/métodos
6.
Anal Bioanal Chem ; 411(14): 3115-3124, 2019 May.
Artigo em Inglês | MEDLINE | ID: mdl-30989266

RESUMO

A novel, sensitive, rapid, and simple fluorescent probe has been developed based on green-synthesized carbon dots (CDs). In this work, CDs have been synthesized from valerian root by hydrothermal method. Transmission electron microscopy (TEM) and dynamic light scattering (DLS) results confirm the formation of CDs with sizes of less than 10 nm. Fluorescence quenching of CDs was due to the aggregation of the negative charges of CDs with the positive charge of imipramine (IMI) and was then used as the signal for determination of IMI. In addition, the cytotoxicity of CDs was determined using the MTT assay. The probe responses under optimum conditions were linear in the range of 1.0-200.0 ng mL-1 with a limit of detection of 0.6 ng mL-1. Afterwards, mesoporous boehmite (MB) was modified with synthesized CDs (CDs/MB). TEM images confirmed MB modification with CDs. In this case, the variations in the fluorescence signal for different concentrations of IMI increased leading to the higher sensitivity for IMI detection. The limit of detection and linear range for determination of IMI with CDs/MB were obtained as 0.2 and 0.5-200.0 ng mL-1, respectively. To evaluate the fluorescent probe, IMI was measured in real samples. Graphical abstract.


Assuntos
Hidróxido de Alumínio/química , Óxido de Alumínio/química , Antidepressivos Tricíclicos/análise , Carbono/química , Corantes Fluorescentes/química , Química Verde , Imipramina/análise , Raízes de Plantas/química , Valeriana/química , Adsorção , Antidepressivos Tricíclicos/sangue , Células HeLa , Humanos , Concentração de Íons de Hidrogênio , Imipramina/sangue , Microscopia Eletrônica de Transmissão , Análise Espectral/métodos , Eletricidade Estática , Difração de Raios X
7.
Chemosphere ; 225: 157-165, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-30875498

RESUMO

A high catalytic system using Cu layered double hydrotalcite (Cu(II)-Mg(II)-Fe(III)LDHs) and hydrogen peroxide (H2O2) was developed for the degradation of ethylbenzene. It was identified that the degradation efficiency of ethylbenzene (0.08 mmol L-1) and TOC removal were 96.1% and 39.7% respectively in the presence of 0.1 g L-1 Cu(II)-Mg(II)-Fe(III)LDHs with (Cu2+ + Mg2+)/Fe3+ molar ratio of 5.0 and 0.16 mmol L-1 H2O2 in 6.0 h. Based on ESR and XPS data, hydroxyl radicals (•OH) were the predominant free radical specials generated from the catalytic decomposition of H2O2 for the degradation of ethylbenzene. The redox of Cu(II)/Cu(III) on the layered Cu(II)-Mg(II)-Fe(III)LDHs surface active sites accounted for the formation of •OH radicals and the cycle of Cu(II) in the Cu(II)-Mg(II)-Fe(III)LDHs/H2O2 system were proposed.


Assuntos
Hidróxido de Alumínio/química , Derivados de Benzeno/química , Cobre/química , Peróxido de Hidrogênio/química , Hidróxido de Magnésio/química , Compostos Organometálicos/química , Catálise , Radical Hidroxila/química , Oxirredução
8.
Molecules ; 24(5)2019 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-30832297

RESUMO

In this study, novel organic⁻inorganic composites were prepared by the complexation of dicarboxylic azo dye (AD) with aluminum⁻magnesium hydroxycarbonate (AlMg⁻LH). This procedure provides an effective method for the stabilization of dicarboxylic organic chromophores on an AlMg-LH host. The structures of the hybrid composites were examined by X-ray diffraction (XRD), secondary ion mass spectrometry (TOF-SIMS), 27-Al solid-state nuclear magnetic resonance (NMR) spectroscopy, thermogravimetric analysis (TGA) and scanning transmission electron microscopy (STEM). The TOF-SIMS method was applied to investigate the metal⁻dye interactions and to monitor the thermal stability of the organic⁻inorganic complexes. Secondary ion mass spectrometry confirmed the presence of a characteristic peak for C18H10O5N2Mg22+, indicating that both carboxylic groups interacted with AlMg-LH by forming complexes with two Mg2+ ions. Modification with hybrid pigments affected the crystal structure of the AlMg-LH mineral, as shown by the appearance of new peaks on the X-ray diffraction patterns. Adsorption of the dicarboxylic chromophore not only led to significantly enhanced solvent resistance but also improved the thermal and photostability of the hybrid pigments. We propose a possible arrangement of the azo dye in the inorganic matrix, as well as the presumed mechanism of stabilization.


Assuntos
Hidróxido de Alumínio/química , Compostos Azo/química , Carbonatos/química , Compostos Inorgânicos/química , Hidróxido de Magnésio/química , Compostos Orgânicos/química , Hidróxido de Alumínio/síntese química , Compostos Azo/síntese química , Carbonatos/síntese química , Compostos Inorgânicos/síntese química , Hidróxido de Magnésio/síntese química , Espectroscopia de Ressonância Magnética , Microscopia Eletrônica de Varredura , Compostos Orgânicos/síntese química , Termogravimetria , Difração de Raios X
9.
Nanoscale ; 11(13): 6422-6430, 2019 Mar 28.
Artigo em Inglês | MEDLINE | ID: mdl-30888347

RESUMO

In this work, nano-hybrid electrospun non-woven mats made of wool keratin combined with diclofenac loaded hydrotalcites (HTD) were prepared and characterized as potential drug delivery systems and scaffolds for fibroblast cell growth. Nano-hybrid electrospun non-woven mats showed a good adaptability to wet skin, effortlessly conforming to the three-dimensional topography of the tissue. Nanosized HTD exercised an overall reinforcing action on the electrospun non-woven mats since the nanohybrid samples displayed a reduced swelling ratio and a slower degradation profile compared to keratin-based nanofiber non-woven mats containing free diclofenac, without negative effects on drug release. The cell viability test indicated a decreased toxicity of the drug when loaded into nanofibers and confirmed the biocompatibility of keratin/HTD electrospun non-woven mats; moreover, a controlled diclofenac release within the first 24 hours does not compromise the fibroblast cell growth in a significant manner.


Assuntos
Hidróxido de Alumínio/química , Bandagens , Queratinas/química , Hidróxido de Magnésio/química , Nanofibras/química , Animais , Anti-Inflamatórios não Esteroides/química , Anti-Inflamatórios não Esteroides/metabolismo , Sobrevivência Celular/efeitos dos fármacos , Diclofenaco/química , Diclofenaco/metabolismo , Liberação Controlada de Fármacos , Camundongos , Microscopia de Fluorescência , Células NIH 3T3 , Nanofibras/toxicidade , Resistência ao Cisalhamento , Viscosidade , Lã/metabolismo
10.
Artigo em Inglês | MEDLINE | ID: mdl-30893920

RESUMO

Flocculation can remove large amounts of nitrogen and phosphorus from wastewater, and the resulting nitrogen- and phosphorus-rich floc can be used to produce organic fertilizer. For biogas slurries containing high levels of nitrogen and phosphorus, ordinary flocculants can no longer meet the flocculation requirements. In this study, to fully utilize the advantages of the two flocculants and achieve efficient removal rates of nitrogen and phosphorus from a biogas slurry, chitosan (CTS) and polyaluminum chloride (PAC) were used as a composite flocculation agent to flocculate pig biogas slurries. The response surface method was used to study the effect of PAC added (PACadded) to the composite flocculant (CF), composite flocculant added (CFadded) to the biogas slurry and the pH on flocculation performance, and optimize these three parameters. In the tests, when the PACadded was 6.79 g·100 mL-1CF, the CFadded was 20.05 mL·L-1 biogas slurry and the pH was 7.50, the flocculation performance was the best, with an absorbance of 0.132 at a wavelength of 420 nm. The total phosphorus (TP) concentration was reduced from 214.10 mg·L-1 to 1.38 mg·L-1 for a removal rate of 99.4%. The total ammonia nitrogen (TAN) concentration was reduced from 1568.25 mg·L-1 to 150.27 mg·L-1 for a removal rate of 90.4%. The results showed that the CF could form larger flocs, and had greater adsorption capacity and more stable flocculation performance than ordinary flocculants. Furthermore, the CF could exhibit better chelation, electrical neutralization and bridge adsorption.


Assuntos
Hidróxido de Alumínio/química , Biocombustíveis , Quitosana/química , Floculação , Amônia/análise , Animais , Nitrogênio/análise , Fósforo/análise , Suínos , Águas Residuárias
11.
Molecules ; 24(3)2019 Feb 03.
Artigo em Inglês | MEDLINE | ID: mdl-30717480

RESUMO

In this study, hybrid pigments based on carminic acid (CA) were synthesized and applied in polymer materials. Modification of aluminum-magnesium hydroxycarbonate (LH) with CA transformed the soluble chromophore into an organic-inorganic hybrid colorant. Secondary ion mass spectroscopy (TOF-SIMS), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), and UV-Vis spectroscopy were used to study the structure, composition, and morphology of the insoluble LH/CA colorant. Successful modification of the LH was confirmed by the presence of interactions between the LH matrix and molecules of CA. XPS analysis corroborated the presence of CA complexes with Mg2+ ions in the LH host. The batochromic shift in UV-Vis spectra of the organic-inorganic hybrid colorant was attributed to metal-dye interactions in the organic-inorganic hybrid colorants. Strong metal-dye interactions may also be responsible for the improved solvent resistance and chromostability of the modified LH. In comparison to uncolored ethylene-norbornene copolymer (EN), a modified EN sample containing LH/CA pigment showed lower heat release rate (HRR) and reduced total heat release (THR), providing the material with enhanced flame retardancy.


Assuntos
Hidróxido de Alumínio/química , Carbonatos/química , Carmim/química , Hidróxido de Magnésio/química , Polímeros/química , Estrutura Molecular , Espectroscopia Fotoeletrônica , Pigmentos Biológicos/química , Termogravimetria , Difração de Raios X
12.
Eur J Pharm Biopharm ; 136: 213-220, 2019 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-30703544

RESUMO

No United States Food and Drug Administration-licensed vaccines protective against Ebola virus (EBOV) infections are currently available. EBOV vaccine candidates currently in development, as well as most currently licensed vaccines in general, require transport and storage under a continuous cold chain in order to prevent potential decreases in product efficacy. Cold chain requirements are particularly difficult to maintain in developing countries. To improve thermostability and reduce costly cold chain requirements, a subunit protein vaccine against EBOV was formulated as a glassy solid using lyophilization. Formulations of the key antigen, Ebola glycoprotein (EBOV-GP), adjuvanted with microparticulate aluminum hydroxide were prepared in liquid and lyophilized forms, and the vaccines were incubated at 40 °C for 12 weeks. Aggregation and degradation of EBOV-GP were observed in liquid formulations during the 12-week incubation period, whereas changes were minimal in lyophilized formulations. Antibody responses against EBOV-GP following three intramuscular immunizations in BALB/c mice were used to determine vaccine immunogenicity. EBOV-GP formulations were equally immunogenic in liquid and lyophilized forms. After lyophilization and reconstitution, adjuvanted vaccine formulations produced anti-EBOV-GP IgG antibody responses in mice similar to those generated against corresponding adjuvanted liquid vaccine formulations. More importantly, antibody responses in mice injected with reconstituted lyophilized vaccine formulations that had been incubated at 40 °C for 12 weeks prior to injection indicated that vaccine immunogenicity was fully retained after high-temperature storage, showing promise for future vaccine development efforts.


Assuntos
Hidróxido de Alumínio/administração & dosagem , Hidróxido de Alumínio/química , Vacinas contra Ebola/administração & dosagem , Vacinas contra Ebola/química , Ebolavirus/efeitos dos fármacos , Doença pelo Vírus Ebola/prevenção & controle , Hidróxido de Alumínio/imunologia , Animais , Composição de Medicamentos , Estabilidade de Medicamentos , Vacinas contra Ebola/imunologia , Ebolavirus/imunologia , Feminino , Liofilização , Doença pelo Vírus Ebola/imunologia , Camundongos , Camundongos Endogâmicos BALB C
13.
J Colloid Interface Sci ; 543: 183-191, 2019 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-30802765

RESUMO

A novel cysteine intercalated copper aluminum layered double hydroxide (CuAl-Cys-LDH) was synthesized and applied as heterogeneous catalyst for activating hydrogen peroxide (H2O2) to degrade rhodamine B (RhB) and 4-Nitrophenol (4-NP). The effects of initial pH, CuAl-Cys-LDH dosage, and H2O2 concentration on RhB and 4-NP removal were comprehensively investigated. The results indicated the intercalation of cysteine into the interlayer of LDH greatly enhanced its catalytic activity and stability. With 0.2 g/L CuAl-LDH and 50 mM H2O2, 93.7% of RhB and 80.2% of 4-NP could be removed in the CuAl-Cys-LDH activated H2O2 system. While the CuAl- LDH activated H2O2 system could only degrade 51.2% of RhB and 46.8% of 4-NP under the identical experimental conditions. Significantly, the CuAl-Cys-LDH catalyzed H2O2 system exhibited high degradation efficiency within a wide pH range from 4.0 to 10.0. Based on the electron paramagnetic resonance (EPR) tests and radical quenching experiments, it was inferred that •OH radical was the dominant species responsible for organic contaminants degradation. Mechanism study revealed that the intercalated cysteine in the interlayer of LDH strongly accelerated the rate-determining conversion of Cu(II) to Cu(I) by oxidation itself to cystine, thus enhanced the catalytic efficiency for H2O2 activation to produce •OH radicals. The findings of this work indicated that CuAl-Cys-LDH is a conveniently prepared and highly efficient and stable catalyst for the degradation of organic contaminants in environmental remediation.


Assuntos
Hidróxido de Alumínio/metabolismo , Cobre/metabolismo , Cisteína/metabolismo , Poluentes Ambientais/metabolismo , Peróxido de Hidrogênio/metabolismo , Hidróxidos/metabolismo , Hidróxido de Alumínio/química , Cobre/química , Cisteína/química , Poluentes Ambientais/química , Peróxido de Hidrogênio/química , Hidróxidos/química , Tamanho da Partícula , Propriedades de Superfície
14.
J Environ Sci (China) ; 79: 25-34, 2019 May.
Artigo em Inglês | MEDLINE | ID: mdl-30784448

RESUMO

The removal of algal organic matter (AOM) is a growing concern for the water treatment industry worldwide. The current study investigates coagulation of non-proteinaceous AOM (AOM after protein separation), which has been minimally explored compared with proteinaceous fractions. Jar tests with either aluminum sulphate (alum) or polyaluminium chloride (PACl) were performed at doses of 0.2-3.0 mg Al per 1 mg of dissolved organic carbon in the pH range 3.0-10.5. Additionally, non-proteinaceous matter was characterized in terms of charge, molecular weight and carbohydrate content to assess the treatability of its different fractions. Results showed that only up to 25% of non-proteinaceous AOM can be removed by coagulation under optimized conditions. The optimal coagulation pH (6.6-8.0 for alum and 7.5-9.0 for PACl) and low surface charge of the removed fraction indicated that the prevailing coagulation mechanism was adsorption of non-proteinaceous matter onto aluminum hydroxide precipitates. The lowest residual Al concentrations were achieved in very narrow pH ranges, especially in the case of PACl. High-molecular weight saccharide-like organics were amenable to coagulation compared to low-molecular weight (<3 kDa) substances. Their high content in non-proteinaceous matter (about 67%) was the reason for its low removal. Comparison with our previous studies implies that proteinaceous and non-proteinaceous matter is coagulated under different conditions due to the employment of diverse coagulation mechanisms. The study suggests that further research should focus on the removal of low-molecular weight AOM, reluctant to coagulate, with other treatment processes to minimize its detrimental effect on water safety.


Assuntos
Compostos de Alúmen/química , Hidróxido de Alumínio/química , Chlorella vulgaris , Poluentes Químicos da Água/química , Purificação da Água/métodos , Carbono/química , Floculação
15.
Chemosphere ; 218: 895-906, 2019 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-30609494

RESUMO

The MnOx was immobilized on the CoAl mixed oxides (CoAlO) derived from hydrotalcites with various anions (CO32-, Cl-, NO3- and SO42-) using the hydration and impregnation methods. The CoAlO oxides modified by KMnO4 were calcined in air at 300 °C to obtain stable oxides, which could be used as catalysts for VOCs (acetone and ethyl acetate) oxidation. CoAlO with CO32- and 30 h of hydration time (CoAlO-C-Mn-30) exhibited a promising catalytic activity (T90 = 173 °C for acetone oxidation; T90 = 175 °C for ethyl acetate), highly superior to CoAlO without KMnO4 modification. The improvement in acetone and ethyl acetate catalytic oxidation was ascribed to the Co3+ and surface adsorbed oxygen species. The increase of Co3+ in the CoAlO-C-Mn-30 oxide thanked to the self-decomposition of KMnO4 and reducibility of Co2+ in the CoAlO oxide during the hydration process. This was also confirmed by XRD and XPS characterization, which showed that Mn cations were enriched on the catalyst surface in the valences of +3 and +4. The catalytic activity of the catalyst remained unchanged in four cycles in the presence of 5.5 vol.% water vapor, which indicated a great potential for industrial application.


Assuntos
Óxidos/química , Permanganato de Potássio/química , Compostos Orgânicos Voláteis/química , Acetatos , Acetona , Adsorção , Hidróxido de Alumínio/química , Catálise , Cobalto/química , Hidróxido de Magnésio/química , Oxirredução
16.
Environ Pollut ; 247: 180-187, 2019 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-30677662

RESUMO

Hydrotalcite (HT) is a layered double hydroxide (LDH), which is considered as a potential adsorbent to remove anion contaminants. In this study, adsorption of chromate (CrO4) and phosphate (PO4) on HT was conducted at various pH and temperatures. Related adsorption mechanisms were determined via the isotherm, kinetic, and competitive adsorption studies as well as the Cr K-edge X-ray absorption fine-structure (XAFS) spectroscopy. The maximum adsorption capacities for CrO4 and PO4 on HT were 0.16 and 0.23 mmol g-1. Regarding adsorption kinetics, CrO4 and PO4 adsorption on HT could be well described by the second order model, and the rate coefficient of CrO4 and PO4 on HT decreased significantly with the increasing pH from 5 to 9. The adsorption kinetics for CrO4 and PO4 were divided into fast and slow stages with the boundary at 15 min. This biphasic adsorption behavior might be partially attributed to multiple reactive pathways including anion exchange and surface complexation. Fitting results of Cr K-edge EXAFS analysis showed a direct bonding between CrO4 and Al on HT surfaces. Such a surface complexation appeared to be the rate-limiting step for CrO4 adsorption on HT. By contrast, the diffusion through the hydrated interlayer space of HT was the major rate-limiting step for PO4. This study determined the adsorption behaviors of CrO4 and PO4 on HT, including the initial transfer process and the subsequent adsorption mechanisms. Such information could improve the strategy to use HT as the potential adsorbent for the remediation of anionic pollutants.


Assuntos
Hidróxido de Alumínio/química , Cromatos/química , Hidróxido de Magnésio/química , Modelos Químicos , Fosfatos/química , Adsorção , Hidróxidos , Cinética , Espectroscopia por Absorção de Raios X
17.
J Colloid Interface Sci ; 541: 12-17, 2019 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-30682589

RESUMO

The present study reports the removal of Bisphenol A (BPA) and Ibuprofen (IBP) using adsorbents prepared from batik sludge. The calcite sludge-aluminum hydroxide (CAl) adsorbent was prepared by calcination and followed by aluminum hydroxide impregnation. The batik sludge and prepared adsorbents were characterized by FESEM, TGA, XRD, FTIR and BET techniques. The maximum adsorption capacity, adsorption time, different initial solution pH, ionic strength and regeneration study of the adsorbents were also investigated. Furthermore, the sorption behavior of the pollutants were studied by the Langmuir and Freundlich isotherms. The deposition of Al(OH)3 enhanced the BPA and IBP adsorption capacity on the CAl surface. The maximum removal capacity of BPA and Ibuprofen were 83.53 mg g-1 and 34.96 mg g-1 for the CAl adsorbent. In addition, the kinetic data for BPA and IBP were fitted to the pseudo first order, pseudo second order, Elovich, parabolic diffusion and power function equations to understand the sorption behavior. The adsorption behavior of BPA and IBP was mainly chemisorption. This study shows that CAl is a promising adsorbent for the removal of BPA and IBP.


Assuntos
Hidróxido de Alumínio/química , Compostos Benzidrílicos/isolamento & purificação , Ibuprofeno/isolamento & purificação , Fenóis/isolamento & purificação , Esgotos/química , Dióxido de Silício/química , Poluentes Químicos da Água/isolamento & purificação , Purificação da Água/métodos , Compostos Benzidrílicos/análise , Concentração de Íons de Hidrogênio , Ibuprofeno/análise , Fenóis/análise , Poluentes Químicos da Água/análise
18.
Biologicals ; 58: 73-75, 2019 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-30660437

RESUMO

A simple method for the determination of low levels of residual formaldehyde in an inactivated Zika vaccine formulated with aluminum hydroxide gel was developed for the assessment of drug product quality. Formaldehyde was reacted with 2,4-dinitrophenylhydrazine (DNPH) and the derivatized product was detected by HPLC with an UV detector at 360 nm. The derivatization reaction could be carried out in a 2-mL HPLC vial and the sample was analyzed directly. The method was fully validated according to the International Conference on Harmonization Q2 guidelines. Aluminum hydroxide gel up to 1.0 mg/mL (aluminum concentration) did not interfere with the determination of formaldehyde in drug product. Formaldehyde concentrations of 0.05 µg/mL (quantitation limit) to 1.00 µg/mL in the Zika vaccine could be precisely determined. Hence, this method proved to be suitable for quality control of the Zika vaccine.


Assuntos
Adjuvantes Imunológicos/química , Hidróxido de Alumínio/química , Formaldeído/análise , Vacinas Virais/química , Zika virus , Humanos
19.
Sci Total Environ ; 652: 1331-1338, 2019 Feb 20.
Artigo em Inglês | MEDLINE | ID: mdl-30586818

RESUMO

Reaction of fluoride with waste oyster shell was studied. To enhance the stability and adsorption capacity, oyster shell was coated with Al(OH)3 and the adsorption behaviors were compared with the uncoated one. When at low fluoride concentration (<30 mg/L), fluoride removal efficiency decreased with increasing pH, and the adsorption could be modeled by Langmuir isotherm. At high fluoride concentration (>100 mg/L), linear adsorption isotherm fitted better, in which the adsorption capacity of fluoride increased linearly with increasing equilibrium fluoride concentration. The coated oyster shell showed higher adsorption capacity and wider workable pH range. From XPS analysis, the presence of CaF2 was confirmed by the peak at 684.7 eV when fluoride concentration increased. It was noted that magnesium content of waste oyster shell reacted with fluoride to form significant fractions of MgF2 whose corresponding peak was detected at 685.6-685.8 eV. For coated oyster shell, fluoride reacted with Ca, Mg, and Al. The reaction mechanism was mainly adsorption at low initial concentration, and precipitation-dominated at higher concentration.


Assuntos
Exoesqueleto/química , Fluoretos/análise , Magnésio/química , Ostreidae/química , Resíduos , Poluentes Químicos da Água/análise , Purificação da Água/métodos , Hidróxido de Alumínio/química , Animais , Cálcio/química , Estudos de Viabilidade , Água Subterrânea/química , Propriedades de Superfície , Taiwan
20.
J Oleo Sci ; 68(1): 95-102, 2019 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-30542011

RESUMO

Oxidative dehydrogenation of ethanol to acetaldehyde over Mg-Al layered double hydroxides (LDH) and their differently calcined derivative catalysts was investigated in this study. The Mg-Al catalysts were synthesized via co-precipitation method and calcined at different temperatures at 450°C, 600°C and 900°C. It revealed that the calcination temperature affected the physicochemical properties and the catalytic activity of these catalysts toward the oxidative dehydrogenation of ethanol. It was found that ethanol conversion increased with increasing reaction temperature from 200 to 400°C, whereas acetaldehyde selectivity decreased. At low reaction temperature (200-300°C), the non-calcined catalyst (Mg-Al-000) showed the highest ethanol conversion, which can be attributed to the hydroxyl groups on surface having acetaldehyde as a major product. The calcination process led to formation of mixed oxide phase in Mg-Al catalysts as proven by the XRD and FT-IR results. The catalyst calcined at 450°C (Mg-Al-450) exhibited the highest basicity as measured by the CO2-TPD with ethanol conversion of 45.8% and acetaldehyde yield of 29.7% at 350°C.


Assuntos
Acetaldeído/síntese química , Hidróxido de Alumínio/química , Etanol/química , Hidróxido de Magnésio/química , Catálise , Modelos Químicos , Oxirredução , Porosidade , Temperatura Ambiente
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