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1.
Chemistry ; 26(6): 1238-1242, 2020 Jan 27.
Artigo em Inglês | MEDLINE | ID: mdl-31743504

RESUMO

We report the first targeted nuclear medicine application of the lanthanum radionuclides 132/135 La. These isotopes represent a matched pair for diagnosis via the positron emissions of 132 La and therapy mediated by the Auger electron emissions of 135 La. We identify two effective chelators, known as DO3Apic and macropa, for these radionuclides. The 18-membered macrocycle, macropa, bound 132/135 La with better molar activity than DO3Apic under similar conditions. These chelators were conjugated to the prostate-specific membrane antigen (PSMA)-targeting agent DUPA to assess the use of radiolanthanum for in vivo imaging. The 132/135 La-labeled targeted constructs showed high uptake in tumor xenografts expressing PSMA. This study validates the use of these radioactive lanthanum isotopes for imaging applications and motivates future work to assess the therapeutic effects of the Auger electron emissions of 135 La.


Assuntos
Lantânio/química , Antígeno Prostático Específico/antagonistas & inibidores , Compostos Radiofarmacêuticos/química , Animais , Linhagem Celular Tumoral , Meios de Contraste/química , Compostos Heterocíclicos com 1 Anel/química , Humanos , Masculino , Camundongos , Tomografia Computadorizada com Tomografia por Emissão de Pósitrons , Antígeno Prostático Específico/metabolismo , Neoplasias da Próstata/diagnóstico por imagem , Compostos Radiofarmacêuticos/metabolismo , Transplante Heterólogo
2.
Environ Sci Pollut Res Int ; 26(36): 36124-36140, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31748998

RESUMO

A rapid growth in the development of power generation and transportation sectors would result in an increase in the carbon dioxide (CO2) concentration in the atmosphere. As it will continue to play a vital role in meeting current and future needs, significant efforts have been made to address this problem. Over the past few years, extensive studies on the development of heterogeneous catalysts for CO2 methanation have been investigated and reported in the literatures. In this paper, a comprehensive overview of methanation research studies over lanthanide oxide catalysts has been reviewed. The utilisation of lanthanide oxides as CO2 methanation catalysts performed an outstanding result of CO2 conversion and improvised the conversion of acidity from CO2 gas to CH4 gas. The innovations of catalysts towards the reaction were discussed in details including the influence of preparation methods, the structure-activity relationships as well as the mechanism with the purpose of outlining the pathways for future development of the methanation process.


Assuntos
Dióxido de Carbono/análise , Lantânio/química , Metano/análise , Gás Natural/análise , Óxidos/química , Catálise
3.
Anal Bioanal Chem ; 411(28): 7511-7518, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31641824

RESUMO

A label-free, rapid response colorimetric aptasensor for sensitive detection of chloramphenicol (CAP) was proposed, which was based on the strategy of ssDNA-modified gold nanoparticle (AuNP) aggregation assisted by lanthanum (La3+) ions. The AuNPs generated a color change that could be monitored in the red, green, and blue and analyzed by the smartphone imaging app. La3+, as a trigger agent, strongly combined with the phosphate groups of the surface of ssDNA-AuNPs probe, which helps create AuNP aggregation and the color change of AuNPs from red to blue. On the contrary, when mixing with CAP, the aptamer (Apt) bound to CAP to form a rigid structure of the Apt-CAP complex, and La3+ attached to the phosphate groups of the complex, which prevented the aptamer from binding to the surface of the AuNPs. As a result, the color of the AuNPs changed to violet-red. Finally, UV-vis absorption spectroscopy and the smartphone imaging app were employed to determine CAP with a lower detection limit of 7.65 nM and 5.88 nM, respectively. The proposed strategy featuring high selectivity and strong anti-interference ability for detection of CAP in practical samples was achieved. It is worth mentioning that the simple and portable colorimetric aptasensor will be used for facilitating on-site detection of food samples.


Assuntos
Técnicas Biossensoriais/métodos , Cloranfenicol/análise , Colorimetria/instrumentação , Ouro/química , Lantânio/química , Nanopartículas Metálicas/química , Smartphone , Animais , Galinhas , Inocuidade dos Alimentos , Leite/química , Produtos Avícolas/análise
4.
Sci Total Environ ; 686: 1185-1193, 2019 Oct 10.
Artigo em Inglês | MEDLINE | ID: mdl-31412514

RESUMO

A novel Fe-Mn-La-impregnated biochar composite (FMLBC) was synthesized using an impregnation method for efficient As (III) adsorption. The pseudo-second-order model (R2 values are 0.996, 0.996, and 0.994 for different FMLBC rate used) better fitted the kinetic adsorption of arsenic (As) on the FMLBC than the pseudo-first order model (R2 values are 0.978, 0.971, and 0.991 respectively). The SEM-EDS, FTIR and XPS results confirmed the addition of Fe, Mn and La into the BC structure. Compared with pristine biochar (3.73 mg g-1) and Fe-Mn-impregnated biochar (9.48 mg g-1), the As (III) adsorption capacity of Fe-Mn-La impregnated biochar (14.9 mg g-1) was significantly improved. The presence of NO3- and SO42- did not influence As adsorption, whereas PO43- influenced As removal. The mechanism of As adsorption on the FMLBC involved oxidization, electrostatic attraction, ligand exchange, and formation of an inner-sphere R-O-As complex. Among them, the electrostatic attraction and inner-sphere complexation contributed the most. The simple preparation process and high adsorption performance suggest that the FMLBC could be served as a promising adsorbent for As (III) removal from aqueous solution.


Assuntos
Arsênico/análise , Carvão Vegetal/química , Eliminação de Resíduos Líquidos/métodos , Poluentes Químicos da Água/análise , Adsorção , Ferro/química , Lantânio/química , Manganês/química
5.
Curr Med Chem ; 26(22): 4280-4295, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31438825

RESUMO

The role metals play in living organisms is well established and subject to extensive research. Some of them participate in electron-exchange reactions. Such reactions cause generation of free radicals that can adversely impact biological systems, as a result of oxidative stress. The impact of 'non-biological' metals on oxidative stress is also a worthy pursuit due to the crucial role they play in modern civilization. Lanthanides (Ln) are widely used in modern technology. As a result, human exposure to them is increasing. They have a number of established medical applications and are being extensively researched for their potential antiviral, anticancer and anti-inflammatory properties. The present review focuses on lanthanum (La) and its impact on oxidative stress. Another metal, widely used in modern high-tech is gallium (Ga). In some respects, it shows certain similarities to La, therefore it is a subject of the present review as well. Both metals exhibit ionic mimicry which allows them to specifically target malignant cells, initiating apoptosis that makes their simple salts and coordination complexes promising candidates for future anticancer agents.


Assuntos
Antineoplásicos/farmacologia , Complexos de Coordenação/farmacologia , Gálio/farmacologia , Lantânio/farmacologia , Neoplasias/tratamento farmacológico , Neoplasias/metabolismo , Estresse Oxidativo/efeitos dos fármacos , Antineoplásicos/química , Apoptose/efeitos dos fármacos , Proliferação de Células/efeitos dos fármacos , Complexos de Coordenação/química , Gálio/química , Humanos , Lantânio/química , Neoplasias/patologia
6.
ACS Appl Mater Interfaces ; 11(35): 31755-31762, 2019 Sep 04.
Artigo em Inglês | MEDLINE | ID: mdl-31393692

RESUMO

Nanoscale metal-organic frameworks (NMOFs) have been proved to be effective quenching platforms for fluorescent detection of DNA via fluorophore-quencher pairs. Zeolitic imidazolate framework-8 (ZIF-8) is one type of the most promising NMOFs because of its excellent biocompatibility and easy preparation. However, ZIF-8 is rarely used as platforms for fluorescence sensing of DNA because of its bad fluorescence quenching property. In this study, lanthanide ions were doped into ZIF-8 to regulate its fluorescence quenching behavior. The La3+ doped ZIF-8 (ZIF-8-La) showed the best quenching efficiency on dye-labeled DNA. The signal-to-background ratio was around 3 times higher than ZIF-8. Furthermore, a core-shell La3+-doped ZIF-8 (CS-ZIF-8-La) was designed to modify more La3+ on the surface of ZIF-8. Compared with ZIF-8-La, the CS-ZIF-8-La exhibited the same fluorescence sensing behavior toward positive-dye-labeled DNA, but showed completely contrary quenching property on the negative-dye-labeled DNA. On the basis of this phenomenon, CS-ZIF-8-La was successfully used as quenching platform for designing a ratiometric sensor for DNA and microRNA.


Assuntos
Aptâmeros de Nucleotídeos/química , DNA/análise , Lantânio/química , Estruturas Metalorgânicas/química , MicroRNAs/análise , Zeolitas/química , Fluorescência , Células HeLa , Humanos
7.
Molecules ; 24(13)2019 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-31266151

RESUMO

The swelling ability of LaNi5 for application to hydrogen-storage-alloy (HSA) actuator is discussed through the measurement of the swelling ratio in hydrogen. The HSA actuator is driven by hydrogen pressure change causing the swelling of HSA. LaNi5 is one of the candidate materials for HSA actuators as well as palladium. Some prototypes of HSA actuators using LaNi5 have been fabricated; however, the kinetic swelling ability of LaNi5 itself has been not investigated. In this paper, the authors investigated the static and kinetic swelling ability of LaNi5 powder under hydrogen atmosphere. The results showed that the swelling ratio increased by 0.12 at the phase transition pressure. Response time decreased with an increase in the charged pressure during absorption, while it remained constant during discharge. Reaction kinetics revealed that these swelling behaviors were explained by hydrogen absorption and lattice expansion. The swelling ability of LaNi5 was also compared with that of palladium. The results show that LaNi5 swells 1.8 times more than palladium under 0.5 MPa. LaNi5 is suitable for an actuator driven repeatedly under more than the phase transition pressure. Palladium can be used for one-way-operation actuator even under 0.1 MPa since its response time during the evacuation was much longer than during the pressurization.


Assuntos
Ligas/química , Hidrogênio/química , Lantânio/química , Níquel/química
8.
Ecotoxicol Environ Saf ; 182: 109396, 2019 Oct 30.
Artigo em Inglês | MEDLINE | ID: mdl-31276888

RESUMO

We report herein the sonochemical synthesis of a lanthanum dioxide carbonate (La2O2CO3) and zinc ferrite (ZnFe2O4)-loaded reduced graphene oxide (LZF-rGO) nanoheterostructure for ultrasound (US)-assisted degradation of methyl orange (MO) from water. The MO was chosen as a model organic dye due to its toxicological and biodegradable-resistant properties. The LZF-rGO catalyst was characterized by scanning electron microscopy, energy-dispersive X-ray spectroscopy, transmission electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy. The results of characterizations confirmed successful synthesis of sonocatalyst. Among different removal systems, US/LZF-rGO displayed outstanding sonodegradation performance for degradation of MO. The maximum removal efficiency of 75.9% was achieved using 0.2 g/L sonocatalyst, 20 mg/L MO, and 0.71 W/cm2 US power intensity for 65 min. MO can be partially adsorbed on LZF-rGO but mostly sonodegraded by reactive radical species. The reaction conditions were optimized by investigating the effect of key operating parameters, including the sonocatalyst dosage, initial MO concentration, US power intensity, presence of inorganic salts, and use of an enhancer, on the decolorization of MO. The degradation intermediates produced from MO during the sonocatalytic process were identified by UPLC®/MS-MS, and possible mechanism and pathway for the degradation of MO in the US/LZF-rGO system were also proposed. Reusability experiments with this sonocatalyst revealed a less than 10% drop in the degradation efficiency after four adsorption-desorption cycles.


Assuntos
Corantes/química , Grafite/química , Lantânio/química , Nanoestruturas/química , Poluentes Químicos da Água/química , Carbonatos , Catálise , Compostos Férricos , Magnetismo , Microscopia Eletrônica de Varredura , Microscopia Eletrônica de Transmissão , Modelos Químicos , Óxidos/química , Espectroscopia Fotoeletrônica , Água , Difração de Raios X , Zinco , Compostos de Zinco , Óxido de Zinco/química
9.
J Colloid Interface Sci ; 554: 520-530, 2019 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-31330425

RESUMO

A one-pot simple procedure for the synthesis of uniform, ellipsoidal Eu3+-doped sodium lanthanum tungstate and molybdate (NaLa(XO4)2, X  = W, Mo) nanophosphors, functionalized with carboxylate groups, is described. The method is based on a homogeneous precipitation process at 120 °C from appropriate Na+, Ln3+ and tungstate or molybdate precursors dissolved in ethylene glycol/water mixtures containing polyacrylic acid. A comparative study of the luminescent properties of both luminescent materials as a function of the Eu3+ doping level has been performed to find the optimum nanophosphor, whose efficiency as X-ray computed tomography contrast agent is also evaluated and compared with that of a commercial probe. Finally, the cell viability and colloidal stability in physiological pH medium of the optimum samples have also been studied to assess their suitability for biomedical applications.


Assuntos
Meios de Contraste/química , Európio/química , Lantânio/química , Substâncias Luminescentes/química , Molibdênio/química , Compostos de Tungstênio/química , Animais , Meios de Contraste/síntese química , Substâncias Luminescentes/síntese química , Tomografia Computadorizada por Raios X , Compostos de Tungstênio/síntese química , Células Vero
10.
Int J Mol Sci ; 20(14)2019 Jul 12.
Artigo em Inglês | MEDLINE | ID: mdl-31336869

RESUMO

In this work, LaPO4:Ce, Tb phosphors were prepared by firing a LaPO4:Ce, Tb precipitate using an ionic-liquid-driven supported liquid membrane system. The entire system consisted of three parts: a mixed rare earth ion supply phase, a phosphate supply phase, and an ionic-liquid-driven supporting liquid membrane phase. This method showed the advantages of a high flux, high efficiency, and more controllable reaction process. The release rate of PO43- from the liquid film under different types of ionic liquid, the ratio of the rare earth ions in the precursor mixture, and the structure, morphology, and photoluminescence properties of LaPO4:Ce, Tb were investigated by inductively coupled plasma-atomic emission spectroscopy, X-ray diffraction, Raman spectra, scanning electron microscopy, and photoluminescence emission spectra methods. The results showed that a pure phase of lanthanum orthophosphate with a monoclinic structure can be formed. Due to differences in the anions in the rare earth supply phase, the prepared phosphors showed micro-spherical (when using rare earth sulfate as the raw material) and nanoscale stone-shape (when using rare earth nitrate as the raw material) morphologies. Moreover, the phosphors prepared by this method had good luminescent properties, reaching a maximum emission intensity under 277 nm excitation with a predominant green emission at 543 nm which corresponded to the 5D4-7F5 transition of Tb3+.


Assuntos
Cério/química , Líquidos Iônicos , Lantânio/química , Metais Terras Raras/química , Fosfatos/química , Fósforo/química , Luminescência , Substâncias Luminescentes/química , Estrutura Molecular , Difração de Raios X
11.
Environ Monit Assess ; 191(8): 488, 2019 Jul 10.
Artigo em Inglês | MEDLINE | ID: mdl-31292792

RESUMO

This paper presents the adsorption capacity of a biosorbent derived from the inner part of durian (Durio zibethinus) rinds, which are a low-cost and abundant agro-waste material. The durian rind sorbent has been successfully utilized to remove lanthanum (La) and yttrium (Y) ions from their binary aqueous solution. The effects of several adsorption parameters including contact time, pH, concentrations of La and Y, and temperature on the removal of La and Y ions were investigated. The adsorption isotherm and kinetics of the metal ions were also evaluated in detail. Both La and Y ions were efficiently adsorbed by the biosorbent with optimum adsorption capacity as high as 71 mg La and 35 mg Y per gram biosorbent, respectively. The simultaneous adsorption of La and Y ions follows Langmuir isotherm model, due to the favorable chelation and strong chemical interactions between the functional groups on the surface of the biosorbent and the metal ions. The addition of oxygen content after adsorption offers an interpretation that the rare-earth metal ions are chelated and incorporated most probably in the form of metal oxides. With such high adsorption capacity of La and Y ions, the durian rind sorbent could potentially be used to treat contaminated wastewater containing La and Y metal ions, as well as for separating and extracting rare-earth metal ions from crude minerals.


Assuntos
Lantânio/química , Poluentes Químicos da Água/química , Ítrio/química , Adsorção , Bombacaceae , Concentração de Íons de Hidrogênio , Íons/química , Cinética , Lantânio/análise , Metais , Temperatura Ambiente , Água/química , Poluentes Químicos da Água/análise , Ítrio/análise
12.
Environ Sci Pollut Res Int ; 26(21): 22010-22020, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-31144178

RESUMO

To effectively remove phosphate pollution and convectively reuse phosphate resource, straw biochar was firstly functionalized with lanthanum ferrite (LaFeO3) via four different methods, including one-step co-precipitation (S-C), two-step co-precipitation (B-C), one-step impregnation (S-E), and two-step impregnation (B-E). LaFeO3/biochar was characterized systematically by a series of characterization methods. The influence of preparation methods, operation conditions on adsorption process, and the regenerability were studied. The products prepared by four methods displayed different physical morphology and chemical analysis proved chemical composition were similar. LaFeO3/biochar exhibited high adsorption capacity, the pseudo-second-order and Sips models were fitted for the adsorption equilibrium. The LaFeO3/biochar exhibited outstanding phosphate adsorption performance with pH values ranging from 2.3 to 10.6; La ions release was similarly negligible, when pH value was higher than 5.27. The adsorption mechanism was studied and inferred that La species is the key to adsorption ability. The results obtained provide better understanding of the adsorption phenomena and indicate the available preparation technologies and potential usefulness of LaFeO3/biochar for removing phosphate pollution. Graphical abstract "."


Assuntos
Lantânio/química , Nanopartículas/química , Fosfatos/química , Adsorção , Carvão Vegetal/química , Compostos Férricos , Cinética
13.
Inorg Chem ; 58(13): 8379-8387, 2019 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-31063357

RESUMO

Modulating the local environment around the emitting ions with component screening to increase the quantum yield and thermal stability is an effective and promising strategy for the design of high-performance fluorescence materials. In this work, smaller Lu3+ was introduced into the La3+ site in a Mn4+-activated LaAlO3 phosphor with the expectation of improving the luminescence properties via lattice contraction induced by cation substitution. Finally, a La1- xLu xAlO3:Mn4+ ( x = 0-0.04) perovskite phosphor with a high quantum yield of 86.0% and satisfactory thermal stability was achieved, and the emission peak at 729 nm well matches with the strongest absorption peak of the Phytochrome PFR. The favorable performances could be attributed to the suppressed cell volume and superior lattice rigidity after the substitution of Lu3+. This work not only obtains a highly efficient La1- xLu xAlO3:Mn4+ ( x = 0.02) phosphor, which holds great potential for application in plant-cultivation light-emitting diodes, but also provides an applicable strategy for further investigation of far-red-emitting phosphors.


Assuntos
Compostos de Alumínio/química , Equipamentos e Provisões Elétricas , Corantes Fluorescentes/química , Lantânio/química , Lutécio/química , Manganês/química , Agricultura/instrumentação , Compostos de Alumínio/síntese química , Compostos de Alumínio/efeitos da radiação , Cor , Corantes Fluorescentes/síntese química , Corantes Fluorescentes/efeitos da radiação , Lantânio/efeitos da radiação , Lutécio/efeitos da radiação , Manganês/efeitos da radiação , Raios Ultravioleta
14.
Int J Biol Macromol ; 133: 253-261, 2019 Jul 15.
Artigo em Inglês | MEDLINE | ID: mdl-30986464

RESUMO

Integrated photocatalytic composite adsorbents (IPCA) are used to degrade toxic organic and inorganic compounds in presence of UV/visible light irradiation. The compound preserves all the existing features of individual components and at the same time overcome drawbacks like rapid recombination of photogenerated electrons, low absorptivity and hindrance effect of the photocatalyst. Herein, an integrated Photocatalytic Chitosan-La3+-Graphite composite adsorbent was synthesized and the resultant composites were characterized by FTIR, XRD, TGA, EDX and SEM analysis. The UV-visible diffusion reflectance spectroscopy (UV-vis DRS) was used for the band gap measurement and it was found to be 3.2 eV. An aqueous solution of methylene blue (MB) dye (30 mL of 100 mg/L) was used to study the photocatalytic efficiency of the prepared IPCA. The Chitosan-La3+-Graphite Composite (CS-La-GR) (100 mg of dosage) exhibits enhanced photocatalytic degradation efficiency (93.5% in 40 min) for Methylene blue under UV light irradiation. The highest photodegradation was due to the stronger adsorption of MB dye on the surface of highly porous IPCA. Moreover, the reactive species, ·OH radical and O2·- radical ions play a major role in the photocatalytic degradation of Methylene blue over composite photocatalyst.


Assuntos
Quitosana/química , Grafite/química , Lantânio/química , Azul de Metileno/química , Fotólise , Adsorção , Catálise , Técnicas de Química Sintética , Concentração de Íons de Hidrogênio , Cinética , Modelos Moleculares , Conformação Molecular
15.
Molecules ; 24(7)2019 Apr 03.
Artigo em Inglês | MEDLINE | ID: mdl-30987150

RESUMO

Since water-soluble porphyrin complexes of lanthanides(III) have proved to be promising for medical applications (e.g., luminescence imaging, photodynamic therapy, and theranostics), the investigation of the formation, photophysical, and photochemical properties of such coordination compounds provides useful pieces of information for their potential usage. Steady-state and time-resolved fluorometry, UV-Vis absorption spectroscopy, and continuous-wave photolysis were utilized for this purpose. 5,10,15,20-Tetrakis(4-sulfonatophenyl)porphyrin formed mono- and bisporphyrin complexes with samarium(III), europium(III), and gadolinium(III) as representatives in the middle of the lanthanide series. The special photoinduced behavior of these compounds was mostly determined by the position of the metal center, which was located out of the ligand plane, thus distorting it. Besides, the photochemical and, especially, photophysical features of the corresponding mono- and bisporphyrin complexes were similar because, in the latter species, two monoporphyrins were connected by a weak metal bridge between the peripheral sulfonato substituents (tail-to-tail dimerization). The formation of these coordination compounds and the transformation reactions between the mono- and bisporphyrins were rather slow in the dark at room temperature. These processes were accelerated by visible irradiation. However, dissociation and, especially, redox degradation were the main photoreactions in these systems, although with low quantum yields. Additionally, depending on the excitation wavelength, new types of photoproducts were also detected.


Assuntos
Ânions/química , Lantânio/química , Processos Fotoquímicos , Fotoquímica , Porfirinas/química , Algoritmos , Európio/química , Gadolínio/química , Modelos Teóricos , Análise Espectral
16.
Environ Sci Pollut Res Int ; 26(12): 12123-12135, 2019 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-30827023

RESUMO

Cobalt oxides have been considered as a kind of highly efficient catalyst for the oxidation of volatile organic compounds (VOCs). In this work, lanthanum-cobalt composite oxides were prepared by using the co-precipitation method, and toluene was used as the model compound. Diversified techniques including XRD, SEM, Raman spectra, XPS, H2-TPR, and N2 adsorption-desorption were applied to investigate the physicochemical properties of as-prepared materials. The composite catalysts showed different morphology including larger specific surface area and higher pore volume which would accelerate the adsorption of toluene and improve the amount of active sites on surface. Moreover, the addition of lanthanum could enhance the low-temperature reducibility, and it could be also beneficial to expose more Co3+ and adsorbed oxygen species on the surface of catalysts which could accelerate the oxidation of toluene and lower onset oxidation temperature. 0.05La-Co (with a molar ratio of lanthanum against cobalt is 0.05) showed the best catalytic performance. The complete conversion of toluene was achieved at 225 °C under the condition of toluene concentration = 1000 ppm and SV = 20,000 ml·g-1·h-1. Stability test over 0.05La-Co was conducted at 225 °C and it could maintain the 100% conversion of toluene for 720 min, indicating the excellent stability of as-prepared catalysts. Undoubtedly, lanthanum-cobalt composite oxide is a kind of promising material for the catalytic oxidation of VOCs.


Assuntos
Temperatura Baixa , Modelos Químicos , Tolueno/química , Adsorção , Catálise , Cobalto/química , Lantânio/química , Oxirredução , Óxidos/química , Oxigênio/química , Propriedades de Superfície , Temperatura Ambiente , Compostos Orgânicos Voláteis/química
17.
Food Chem ; 286: 191-196, 2019 Jul 15.
Artigo em Inglês | MEDLINE | ID: mdl-30827595

RESUMO

In current research, a sensitive screen printed electrochemical sensor on the basis of La3+-doped Co3O4 nanocubes was fabricated to determine sudan I. The electrochemical performance of sudan I at this sensor was investigated in detail, presenting that this sensor had electrocatalytic behavior for oxidizing sudan I due to the significant peak current enhancement and the dropping of oxidation overpotential. Under the optimum conditions, the linear response range for sudan I concentrations by the modified sensor was 0.3-300.0 µM, and detection limit was 0.05 µM. Lastly, the suggested technique was also studied as a selective, easy, and exact electrochemical sensor to determine sudan I in food samples, including chili powder, tomato paste, and ketchup sauce.


Assuntos
Técnicas Eletroquímicas/métodos , Análise de Alimentos/métodos , Lantânio/química , Nanoestruturas/química , Naftóis/análise , Cobalto/química , Técnicas Eletroquímicas/instrumentação , Análise de Alimentos/instrumentação , Corantes de Alimentos/análise , Limite de Detecção , Naftóis/química , Oxirredução , Óxidos/química
18.
Bioresour Technol ; 278: 248-254, 2019 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-30708327

RESUMO

Biomass catalytic pyrolysis with various metals (Zn, Fe, Ca, Ce and La) modified ZSM-5 catalysts were analyzed, in order to investigate the relationship between the physicochemical properties of catalysts and the benzene, toluene and xylene (BTX) products. Results revealed that the BTX products were positively correlated with the strong acid site contents of the catalysts. Appropriate amount (0.5-4 wt%) of loaded Zn species increased the strong acid site contents of the catalysts as well as BTX yields, and the highest yield of BTX was observed under Zn loading amount of 2 wt%. While excessive metal loading amount (10 wt%) decreased both the acidity and the physical properties of the catalyst, resulting in poor diffusion of reactants and products in the channel and decreased the BTX yield. It is recommended that ZSM-5 catalyst with higher strong acid site content and pore volume should be used for BTX production.


Assuntos
Benzeno/química , Tolueno/química , Xilenos/química , Zeolitas/química , Biomassa , Cálcio/química , Catálise , Fenômenos Químicos , Lantânio/química , Metais Pesados/química , Pirólise
19.
Int J Biol Macromol ; 130: 527-535, 2019 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-30794900

RESUMO

The potential of hydrothermal technology was utilized for the preparation of promising adsorbents in order to overcome the troubles of methemoglobinemia (blue baby syndrome) and eutrophication which is caused by excess nitrate (NO3-) and phosphate (PO43-) ions in water. Hence, in the present investigation, the chitosan (CS) encapsulated lanthanum oxide (La2O3) admixed Aegle marmelos(AM) (La2O3AM@CS) composite beads was prepared by both in situ precipitation (In situ) and hydrothermal (Hydro) methods for NO3- and PO43- adsorption. The hydro supported La2O3AM@CS composite beads hold an enhanced nitrate and phosphate sorption capacity (SC) of 27.84 and 34.91 mg/g than the other adsorbents prepared by in situ method. The characterization studies of the adsorbents such as FTIR, XRD, SEM and BET analysis were explored in detail. In batch scale, the adsorption affecting parameters such as contact time, pH, adsorbent dosage, initial adsorbate strength, competing anions and temperature was optimized. The fitted experimental data of various isotherms and thermodynamic parameters supports the feasible nature of NO3- and PO43- adsorption system. The field trial investigations and reuse of La2O3AM@CS composite beads were also executed.


Assuntos
Aegle/química , Quitosana , Lantânio , Nitratos , Óxidos , Fosfatos , Adsorção , Quitosana/química , Concentração de Íons de Hidrogênio , Íons , Lantânio/química , Nanocompostos/química , Nanocompostos/ultraestrutura , Nitratos/química , Óxidos/química , Fosfatos/química , Análise Espectral , Temperatura Ambiente , Termodinâmica
20.
Int J Biol Macromol ; 130: 491-498, 2019 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-30794904

RESUMO

The iron - lanthanum mixed oxyhydroxide (FLMOH) and chitosan engraved iron - lanthanum mixed oxyhydroxide materials (CSFLMOH) were prepared successfully and utilized for the hexavalent chromium adsorption studies. The physicochemical properties of pristine and Cr(VI) treated adsorbents were characterized using XRD, FTIR, SEM with EDX, TGA and DSC analysis. The efficacy of the CSFLMOH was compared with FLMOH towards the uptake of Cr(VI) ions and was explored using batch technique under various influencing parameters viz., time, dose, pH, initial concentration and co-existing anions. Langmuir, Freundlich and Dubinin - Radushkevich isotherms were used to analyze the adsorption behavior at 303, 313 and 323 K. The rate of the reaction was calculated using reaction based and diffusion-based models. Recycle and reuse studies were demonstrated using 0.05 M NaOH as the desorbing medium.


Assuntos
Quitosana/química , Cromo/química , Ferro/química , Lantânio/química , Adsorção , Concentração de Íons de Hidrogênio , Cinética , Modelos Teóricos , Análise Espectral , Termodinâmica , Poluentes Químicos da Água/química , Purificação da Água/métodos
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