In this work, we report the facile hydrothermal synthesis of manganese cobaltite nanoparticles (MnCo
2
O
4.5
NPs) which can efficiently activate peroxymonosulfate (PMS) for the generation of sulfate ...free radicals (SO
4
&z.rad;
−
) and degradation of organic dyes. The synthesized MnCo
2
O
4.5
NPs have a polyhedral morphology with cubic spinel structure, homogeneously distributed Mn, Co, and O elements, and an average size less than 50 nm. As demonstrated, MnCo
2
O
4.5
NPs showed the highest catalytic activity among all tested catalysts (MnO
2
, CoO) and outperformed other spinel-based catalysts for Methylene Blue (MB) degradation. The MB degradation efficiency reached 100% after 25 min of reaction under initial conditions of 500 mg L
−1
Oxone, 20 mg L
−1
MnCo
2
O
4.5
, 20 mg L
−1
MB, unadjusted pH, and
T
= 25 °C. MnCo
2
O
4.5
NPs showed a great catalytic activity in a wide pH range (3.5-11), catalyst dose (10-60 mg L
−1
), Oxone concentration (300-1500 mg L
−1
), MB concentration (5-40 mg L
−1
), and temperature (25-55 °C). HCO
3
−
, CO
3
2−
and particularly Cl
−
coexisting anions were found to inhibit the catalytic activity of MnCo
2
O
4.5
NPs. Radical quenching experiments revealed that sulfate radicals are primarily responsible for MB degradation. A reaction sequence for the catalytic activation of PMS was proposed. The as-prepared MnCo
2
O
4.5
NPs could be reused for at least three consecutive cycles with small deterioration in their performance due to low metal leaching. This study suggests a facile route for synthesizing MnCo
2
O
4.5
NPs with high catalytic activity for PMS activation and efficient degradation of organic dyes.
Catalytic degradation of organic dyes
via
manganese cobaltite nanoparticles-activated peroxymonosulfate.
By a simple wet-chemical procedure using a permanganate in the acidic medium, diatomite coated with amorphous manganese oxide nanoparticles was synthesized. The structural, microstructural and ...morphological characterizations of the as-synthesized catalysts confirmed the nanostructure of MnO2 and its stabilization on the support - diatomite. The highly efficient and rapid degradation of methylene blue and methyl orange over synthesized MnO2 coated Diatomite has been carried out. The results revealed considerably faster degradation of the dyes against the previously reported data. The proposed mechanism of the dye-degradation is considered to be a combinatorial effect of chemical, physicochemical and physical processes. Therefore, the fabricated catalysts have potential application in waste water treatment, and pollution degradation for environmental remediation.
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•Catalytic degradation of methylene blue and methyl orange with MnO2-coated Diatomite.•A simple wet-chemical method is adopted to synthesize MnO2-diatomite nanocomposite.•Large surface area into porous matrix of biosilica provides high active sites.•Reduction of MnIV to MnII produces hydroxyl radicals to chemically degrade the dyes.•Layered structure of birnessite MnO2 provides adsorption of dye molecules.
An electro-Fenton system, which consists of a Pt gauze anode and a commercial carbon felt cathode, is commonly employed to generate in situ hydrogen peroxide, hydroxyl radical and regenerate ferrous ...catalyst for glyphosate degradation (a widely used herbicide in Vietnam) in aqueous solution. The absorbance measurements used to determine the glyphosate concentration during the electrolysis proved that glyphosate was degraded by pseudo-first-order kinetic. The influence of pH, current density, catalyst concentration and initial content of the glyphosate on mineralisation efficiency were studied by monitoring the total organic carbon (TOC) and hydrogen peroxide concentration during electrolysis. The results show that the maximal removal percentage of glyphosate was 91.91% with applied current density of 10 mA cm
−2
, pH 3, 0.1 mM Fe
2+
, 0.05 M Na
2
SO
4
, and 0.1 mM glyphosate in 40 min. The degrading rate constant of glyphosate degradation was calculated to be k
app
= 0.063 min
−1
. In this 91.91% removal, 81.65% of glyphosate was mineralised and the remainder consists of intermediates produced during the electro-Fenton process.
We propose a latent linear mixed model to analyze multivariate longitudinal data of multiple ordinal variables, which are manifestations of fewer continuous latent variables. We focus on the latent ...level where the effects of observed covariates on the latent variables are of interest. We incorporate serial correlation into the variance component rather than assuming independent residuals. We show that misleading inference may be drawn when misspecifying the variance component. Furthermore, we provide a graphical tool depicting latent empirical semi‐variograms to detect serial correlation for latent stationary linear mixed models. We apply our proposed model to examine the treatment effect on patients having the amyotrophic lateral sclerosis disease. The result shows that the treatment can slow down progression of latent cervical and lumbar functions.
Green synthesis has emerged as a sustainable approach for the fabrication of nanomaterials in the last few decades. Leaf extracts have been considered low-cost and highly efficient reactants for the ...synthesis of nanoparticles. In this study, an aqueous extract of Cleistocalyx operculatus leaves was employed as a reductant to synthesize Ag/TiO2 nanocomposites. The morphology, structure, and interface interaction of the Ag/TiO2 nanocomposites were investigated by (i) X-ray diffraction (XRD) to determine the crystallinity, (ii) scanning electron microscopy (SEM) to determine the morphologies, (iii) energy dispersive X-ray spectroscopy (EDX) to determine the elemental composition and distribution, and (iv) diffuse reflectance spectroscopy (DRS) to understand the optical properties. The results showed that Ag nanoparticles (AgNPs) with particle sizes of 20–40 nm homogeneously covered the surface of the TiO2 nanoparticles. The green-synthesized Ag/TiO2 nanocomposite also exhibited an excellent photodegradation ability for Rhodamine B with a removal percentage up to 91.4% after 180 min of photocatalytic reaction.
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•Green synthesis of Ag/TiO2 nanocomposites using Cleistocalyx operculatus leaf extract.•Comprehensive characterizations of Ag/TiO2 nanocomposites prepared by green synthesis.•Ag nanoparticles (AgNPs) uniformly covered the surface of TiO2 nanoparticles.•The AgNPs were coated with polysaccharides of the leaf extract to prevent oxidation.•Biosynthesized Ag/TiO2 nanocomposites possess excellent photodegradation property.
In this study, Mn2O3/MIL-100(Fe) composite was successfully synthesized by the hydrothermal method and applied for photocatalytic removal of rhodamine B (RhB) in water. The physical and chemical ...properties of the synthesized materials were characterized by XRD, FTIR, SEM, UV-visible, and BET analyses. Experimental results showed a great enhancement in the photocatalytic ability of the Mn2O3/MIL-100(Fe) composite as compared to individual Mn2O3 or MIL-100(Fe) under visible light and persulfate activation. The affecting factors such as pH, photocatalyst dose, RhB concentration, and Na2S2O8 concentration were investigated to find out the best conditions for efficient photocatalysis. By conducting a radical quenching test, all radicals of HO·, SO4·−, 1O2, and O2·− were found to be important in photocatalytic decomposition. The mechanism was proposed for the enhancement of photocatalytic RhB removal via band potential calculation, charge separation, surface redox reaction, and key reactive oxidation species. With its durability, reusability, and high efficiency, the Mn2O3/MIL-100(Fe) composite emerges as a potential photocatalyst working under visible light for application in wastewater treatment.
SUePDF is a graphical user interface program written in MATLAB to achieve quantitative pair distribution functions (PDFs) from electron diffraction data. The program facilitates structural studies of ...amorphous materials and small nanoparticles using electron diffraction data from transmission electron microscopes. It is based on the physics of electron scattering as well as the total scattering methodology. A method of background modeling is introduced to treat the intensity tail of the direct beam, inelastic scattering and incoherent multiple scattering. Kinematical electron scattering intensity is scaled using the electron scattering factors. The PDFs obtained after Fourier transforms are normalized with respect to number density, nanoparticle form factor and the non‐negativity of probability density. SUePDF is distributed as free software for academic users.
SUePDF is software to convert electron diffraction data to quantitative pair distribution functions.
Al/AlOx/Al Josephson junctions are the building blocks of a wide range of superconducting quantum devices that are key elements for quantum computers, extremely sensitive magnetometers and radiation ...detectors. The properties of the junctions and the superconducting quantum devices are determined by the atomic structure of the tunnel barrier. The nanoscale dimension and disordered nature of the barrier oxide have been challenges for the direct experimental investigation of the atomic structure of the tunnel barrier. Here we show that the miniaturized dimension of the barrier and the interfacial interaction between crystalline Al and amorphous AlOx give rise to oxygen deficiency at the metal/oxide interfaces. In the interior of the barrier, the oxide resembles the atomic structure of bulk aluminium oxide. Atomic defects such as oxygen vacancies at the interfaces can be the origin of the two-level systems and contribute to decoherence and noise in superconducting quantum circuits.
Microfluidic systems are an emerging technology to fabricate uniform spherical microparticles. This study employed a flow-focusing microfluidic device (MFFD) to produce uniform sodium alginate ...microdroplets by controlling the continuous (soybean oil) and dispersed (sodium alginate solution) flow rates. The resultant hydrogel particles were spherical in shape with diameters ranging from 70 to 100μm, and a size distribution under 10%, depending on the experimental conditions. Observations of dried calcium alginate microparticles using scanning electron microscopy showed a surface characterized by the uniform distribution of regular nodules. The resultant biomaterials were further examined and evaluated in terms of the removal of toxic metals (Cu2+ and Ni2+ ions); they demonstrated excellent removal performance. The highest adsorption capacities of the prepared calcium alginate microparticles toward Cu2+ and Ni2+ ions were 0.36 and 0.81 mg/mg alginate microparticles, respectively. Thus, calcium alginate microparticles prepared by MFFD demonstrated the potential for toxic metal treatment at different concentrations with short duration and stability. This approach may also be controlled to prepare microparticles that are narrow in size distribution and exhibit uniform morphology.
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•Synthesis of hydrogel calcium alginate microparticles using a microfluidic device.•The toxic metal adsorption behavior of the microparticles was investigated.•Flow rates (ml/h) of 0.1 (alginate) & 6 (soybean oil) yielded uniform particles.•The adsorption capacities (mg/mg) for Cu & Ni ions were 0.36 & 0.81, respectively.
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