Synthesis Of Microspheres Research Articles

Synthesis of CaMoO4 microspheres with enhanced sonocatalytic performance for the removal of Acid Orange 7 in the aqueous environment

Herein, a series of CaMoO4 microspheres were prepared at different pH values by the hydrothermal method. The sonocatalytic performances of the prepared CaMoO4 microspheres were estimated by the removal of Acid Orange 7 (AO7) as a model of organic pollutants. The results showed that the synthesis pH had a great influence on the morphology and the sonocatalytic performance of CaMoO4. The CaMoO4 microspheres prepared at pH = 7 (CaMoO4-7) exhibited superior sonocatalytic performance. The removal ratio of AO7 using CaMoO4-7 as a sonocatalyst was 97.02 ± 0.65%. The sonocatalytic removal of AO7 in the presence of CaMoO4-7 was mainly attributed to the generation of hydroxyl radical (•OH), superoxide anion radical (•O2−) and holes (h+). The optimized operational conditions, such as CaMoO4-7 dose, initial concentration of AO7, initial pH of AO7, ultrasonic power and ultrasonic time were 1.0 g/L, 5 mg/L, pH = 5, 200 W and 120 min, respectively. In addition, CaMoO4-7 had excellent reusability and stability in the sonocatalytic removal process. These results indicated that CaMoO4-7 had the potential as the sonocatalyst to apply in the environmental remediation.

Quick approach for optimization of monodisperse microsphere synthesis with a knowledge sharing strategy powered by machine learning

In this communication, we proposed Bayesian optimization acceleration strategy by allowing machine-learned knowledge to flow across different reaction scales. Dispersion polymerization was conducted to validate this knowledge sharing approach. By learning a product uniformity landscape and performing virtual optimization using high-throughput small-scale reaction data, the most promising recipe subspace was extracted from the full-factorial parameter space for batch-size synthesis optimization. The subsequent Bayesian optimizer was hereby able to traverse the subspace and locate a recipe giving large uniform particles (>10 µm). This highly flexible and efficient strategy can be extended to a diverse library of reactions beyond microsphere synthesis.

Polyethyleneimine-grafted polyphosphazene microspheres for rapid and efficient capture of anionic dyes from wastewater

Developing novel adsorbent to capture organic contaminants from wastewater rapidly and efficiently is highly desirable for waste treatment and environmental restoration. Herein, we reported a new amino-rich spherical adsorbent (PZS-PEI) for highly-efficient uptake of anionic dyes from aqueous solution. The PZS-PEI adsorbent was fabricated through a two-step process including synthesis of PZS-Cl microspheres via room temperature polymerization of hexachlorocyclotriphosphazene with bis(4-hydroxyphenyl) sulfone and subsequent surface grafting reaction of PZS-Cl microspheres using branched polyethyleneimine (PEI). The microstructure of as-obtained PZS-PEI microspheres was fully characterized by scanning electron microscopy, Fourier transform infrared, X-ray photoelectron spectroscopy, zeta potential, and N2 adsorption test. The adsorption performance of the PZS-PEI microspheres towards organic dyes was evaluated through carrying out a series of studies including various influence factor analysis, adsorption isotherm, kinetics, and thermodynamics. Results show that the PZS-PEI adsorbent owned good adsorption selectivity towards anionic dyes, and the maximum adsorption capacities for methyl orange (MO), acid chrome blue K, eosin-Y reached 190.29, 152.90, and 92.34 mg/g at 25 °C, respectively. In addition, the uptake behavior of organic dye by the PZS-PEI adsorbent conformed to Freundlich isotherm and pseudo-second order kinetic model, and the adsorption process followed a three-stage intraparticle diffusion mode with an endothermic and spontaneous characteristic. Electrostatic interaction and hydrogen bonding were responsible for the highly-efficient adsorption of the PZS-PEI adsorbent towards typical anionic dye MO.

Facile synthesis and cation distribution of MgCo2O4 microspheres as anode material for lithium ion batteries

MgCo2O4 microspheres were synthesized through a facile solvothermal method. The as-synthesized microspheres were about 3–8 μm in diameter and were assembled closely by nanoparticles. The cation distribution and cobalt (Co) valence were studied by X-ray photoelectron spectroscopy (XPS). Co3+ and Co2+ ions were all present in the samples. Co3+ ions were located in the octahedral sites and Co2+ occupied both tetrahedral and octahedral sites of the spinel structure, the inversion degree was 0.22–0.17 and slightly decreased with increasing calcination temperature. The electrochemical performance of the samples as anode materials for lithium-ion batteries (LIBs) was studied, the result showed that the sample calcined at 400 °C displayed the largest initial discharge capacity of 1120 mA h·g−1 and the capacity decreased with increasing temperature.

Synthesis of chitosan-lysozyme microspheres, physicochemical characterization, enzymatic and antimicrobial activity

Chitosan microspheres (CMS) by the emulsion-chemical cross-linking method with and without lysozyme immobilization were synthesized and characterized. The technique conditions were adjusted, and spherical particles with approximate diameters of 3.74 ± 1.08 μm and 0. 29 ± 0.029 μm to CMS and chitosan-lysozyme microspheres (C-LMS), respectively, were obtained. The microspheres were characterized by scanning electron microscopy (FESEM), Spectroscopy Fourier Transform Spectroscopy (ATR-FTIR), X-ray diffraction (XRD), and zeta potential. Particle size was identified by laser light scattering (DLS) and the thermal properties by Differential Scanning Calorimetry (DSC) and Thermogravimetry (TGA) were determined. By the lysis of Micrococcus lysodeikticus, the activity of the microspheres was determined, and the results correlated with the amount of lysozyme used in the immobilization process and the enzyme loading efficiency was 67%. Finally, release tests pointed out the amount of enzyme immobilized on the microsphere surface. These results showed that chitosan microspheres could be used as material for lysozyme immobilization by cross-linking technique. The antimicrobial activity was tested by inhibition percent determination, and it evidenced both chitosan microspheres (CMS) and chitosan-lysozyme microspheres (C-LMS) positive antimicrobial activity to Staphylococcus aureus, Enterococcus faecalis and Pseudomonas aeruginosa.

Voltammetric determination of hydrogen peroxide using MoS2 modified glassy carbon electrodes

We report the facile synthesis of MoS2 microspheres and the construction of MoS2/glassy carbon electrodes (GCE) for the precise detection of hydrogen peroxide (H2O2). The electrochemical performance of MoS2 modified GCE was investigated by using cyclic voltammetry (CV). High surface area and good electrical conductivity of MoS2 microspheres facilitated the superior electrocatalytic reduction of H2O2. MoS2/GCE sensor displayed high sensitivity, linearity in detection from 10 to 100 µM with the lower detection and quantification limits of 1.13 µM and 3.82 µM.

One-step preparation of photoclick method for embolic microsphere synthesis and assessment for transcatheter arterial embolization

Vascular embolization is a well-known therapeutic treatment against hepatocellular carcinoma. However, existing embolic agents require complex synthesis, toxic organic solvents and sometimes produce only low yields. In this study, a novel photopolymerization technique, which addresses these issues, was used to prepare embolic microspheres successfully from the sucrose multi-allyl ether monomer in one step. Compared to the preparation of such microspheres always involved in multiple steps or complicated conditions, we obtained the microspheres used photoclick method in a soft template with simple, economic and feasible procedure. This work focuses on the synthesis of new materials by conducting a photopolymerzation in the presence of the sucrose monomer and the photoinitiator. Then, the embolic microspheres obtained were characterized by morphology assay, degradation, and swelling test. Cell experiments showed that the microspheres had good biocompatibility. Rabbit embolizations showed that the microspheres had long-term embolic effects. It is manifested that one-step preparation of photoclick method hold great potential and competitiveness of being used in preparation embolic microspheres in clinic.

Scalable synthesis of monodisperse and recyclable sulphonated polystyrene microspheres for sustainable elimination of heavy metals in wastewater

ABSTRACT Herein, we demonstrate a scalable method for fabricating monodisperse sulphonated polystyrene (SPS) microspheres with abundant sulphonic acid groups and excellent heavy metal removal ability. A comprehensive characterization through SEM, EDS, FT-IR, TG, XRD and XPS confirmed the formation of the SPS microspheres. Take advantage of the abundant sulphonic acid groups on the surface of microspheres, as well as the superior monodisperse properties, adsorption ability of SPS microspheres both in quantity and speed have been enhanced. The adsorption equilibrium obeyed the Langmuir isotherm model with the theoretical maximum capacities of 49.16, 15.38 and 13.89 mg·g−1 for Pb2+, Zn2+ and Cu2+, respectively (30°C, pH = 3.5). Besides, the adsorption equilibriums of Pb2+ onto SPS microspheres can be achieved within only 1 min and the adsorption kinetics can be fitted by a pseudo-second-order kinetics model. More importantly, because of the micron structure of the SPS microspheres, it could overcome the excessive hydrophilia brought by rich sulphonic acid groups and thereby easily separated, which maintain a good recyclable capacity after five regeneration cycles. With the excellent adsorption ability and reusability, SPS microspheres can efficiently handle the polluted water in a convenience and rapid process, which satisfies the sustainable pollution treatment in heavy metals elimination.

Morphology-controlled self-assembly synthesis and excellent microwave absorption performance of MnO2 microspheres of fibrous flocculation

Pure dielectric absorbers with a tunable wide-band response and strong attenuation capability for electromagnetic wave (EMW) absorption are challenging to synthesize. Herein, a series of hierarchical MnO2 microspheres composed of MnO2 nanofibers are synthesized via a simple one-step hydrothermal method. By varying the hydrothermal synthesis conditions, the surface architectures of the MnO2 microspheres could be adjusted, thereby tuning their EMW absorption performance. In addition, nickel doping causes defects in the MnO2 nanofibers, which further boosts microwave absorption performance. Compared to 2D MnO2 nanorods, the hierarchical microspheres formed by the self-assembly of MnO2 nanofibers offer tunable microwave absorption in the X and Ku bands. The Ni-doped microspheres with the optimized morphology show a maximum reflection loss of −40 dB is observed at 8.31 GHz, and an effective absorption bandwidth of 6.1 GHz at 2 mm thickness.

Additive-free synthesis of BiVO4 microspheres as an electrochemical sensor for determination of antituberculosis drug rifampicin

The electrochemical sensor is a promising application that needs highly active materials for fabricating electrode of long cyclic stability, high surface area, low detection limit, excellent selectivity, and reproducibility. Herein, we successfully synthesized the bismuth vanadate microspheres via a simple additive-free facile coprecipitation method. Various spectral characteristic methods such as X-ray diffraction (XRD), Fourier transforms infrared (FT-IR), Raman, Ultra-violet diffractive reflectance spectroscopy (UV-DRS), and field emission scanning microscope (FE-SEM) analysis to examine the structural, surface morphology, and optical properties of as-prepared material. The electrochemical behavior of as-proposed bismuth vanadate modified screen-printed carbon electrode (BV/SPCE) was evaluated by the sensing of rifampicin (RF) through cyclic voltammetry (CV) and linear sweep voltammetry (LSV) systems. As a result, the oxidation peak current of BV/SPCE demonstrated good linearity with the linear concentration of RF ranges from 0.2 to 310 µM, and a low detection limit of 0.014 μM, respectively. The constructed electrode showed high selectivity against various organic and metal ions interference. The stability of the modified sensor exhibited excellent cyclic stability up to 100 cycles. The fabricated electrode was further detected to RF in human urine and serum samples with observed results are acceptable. The schematic illustration for the preparation of the BiVO 4 microspheres and its electrochemical detection of RF. • BiVO 4 microspheres were synthesized through the additive-free facile coprecipitation route. • BiVO 4 modified electrode displays a wide linear range of 0.2–310 µM with a low detection limit of 0.014 µM for the RF sensor. • The fabricated sensor offers excellent selectivity, reproducibility, repeatability, and cyclic stability towards the sensing of RF. • RF was successfully applied to real samples with satisfactory results.

Graphene oxide-MnO2-goethite microsphere impregnated alginate: A novel hybrid nanosorbent for As (III) and As (V) removal from groundwater

This study presents a simple method for facile synthesis of core-shell microspheres of Graphene oxide-MnO2-Goethite (GO-MnO2-Goe). Synthesised GO was used as the core material for treatment with the pre-decided molar ratio mixture of Fe and Mn to form a MnO2-Goe shell over the GO surface optimising various parameters. Subsequently the GO-MnO2-Goe nanoparticles were impregnated into alginate polymer to form GO-MnO2-Goethite impregnated alginate hydrogel beads (GO-MnO2-Goe-Ca-Alg) using displacement reaction. The product was characterized by XRD, FTIR, BET, SEM-EDS and zeta potential measurement. The GO-MnO2-Goe-Ca-Alg hybrid nanosorbent was used to efficiently remove both arsenic (III) and arsenic (V) from groundwater (80–96 % for 0.1−100 μg mL−1 concentration range) at pH 4–6. Uptake processes for both As (III) and As (V) followed Langmuir isotherm model with maximum sorption capacity evaluated as 27.53 and 34.17 mg g-1 respectively for As (III) and As (V). The reaction kinetics, thermodynamic parameters, interparticle diffusion model were studied. Mechanism of uptake was suggested based on fraction diagram of As (III) and As (V) species along with zeta potential of GO-MnO2-Goe at various pH. The in-situ transformation of As (III) to As (V) before its sorption was investigated and explained with the help of XPS analysis.

Facile synthetic approach to produce optimized molybdenum carbide catalyst for alkaline HER

Mo-based materials were recognized as cost-effective electrocatalysts for the hydrogen evolution reaction (HER) in acidic media but were hardly investigated in alkaline media due to the limited active sites, lower conductivity and high water dissociation energy barrier. Herein, a facile, low cost, scalable technique is provided for the synthesis of Mo2C microspheres by a solvothermal route. Varying the feed ratio of the precursors enabled us to control the valence states of Mo and achieve optimized Mo2C phase formation for HER catalysis. Electrodes with the microspherical Mo2C catalyst were stable and exhibited reduced overpotentials of 138 mV at 10 mA cm−2 in 0.5 M KOH with a Tafel slope of 85 mV dec−1. The formation of an active Mo2C phase with abundance of Mo3+/Mo2+ active sites in the suitable ratio, as well as fast charge-transfer kinetics, are proposed as the origin for the efficient HER activity. Notably, we used cyclooctatetraene, an industrial byproduct that can be recycled into functional materials for green energy. Our work provides facile and novel way to design and fabricate Mo2C-based electrocatalyst for HER and probably other green energy applications.

Facile synthesis of Fe3S4 microspheres as advanced anode materials for alkaline iron-based rechargeable batteries

A new kind of spherical Fe3S4 with a 3D hierarchical structure, which is constructed with many intercrossed nanorods, is successfully synthesized via a facile hydrothermal method. The achieved Fe3S4 microspheres are evaluated as advanced anode materials for alkaline iron-based secondary batteries for the first time. Influences of hydrothermal temperature on the physical and electrochemical performances of Fe3S4 particles are investigated systematically. It is found that the Fe3S4 fabricated at 150 °C exhibits better electrochemical properties than the ones obtained at other temperatures, including higher discharge capacity, attractive high-rate capability and good cycling stability. At 0.2, 0.4, 1.0, 2.0, and 5.0 C, the Fe3S4(150 °C) delivers discharge capacity of ~328.5, ~307.6, ~280.5, ~235.9, and ~169.5 mAh g−1, respectively. Especially, after 400 cycles at 1 C/1 C, the Fe3S4(150 °C) presents capacity retention of 88.61%. The pronounced performance of Fe3S4 is attributable to its inherent electrochemical activity, unique 3D hierarchical structure, and high S content, eventually resulting in the reduced charge transfer resistance, improved reversibility, and a beneficial porous electrode structure during cycling. Therefore, the as-achieved Fe3S4 microspheres are promising anode materials for high-performance alkaline iron-based batteries.

Design and Synthesis of CaMoO4 Microspheres and Their Optical Properties

CaMoO4 microspheres materials were prepared by hydrothermal synthesis method using CaCl2 or Ca(NO3)2 and ammonium molybdate as reaction raw material at 170°C. XRD analysis shows that the product indexed to tetragonal phase of CaMoO4. FESEM images exhibit that the product is spherical and the diameter of the microsphere is about 5 μm. PL spectrum indicates that the photoluminescence emissions intensity of CaMoO4 depended on the morphologies and sizes of the products.

Continuous synthesis of monodisperse silica microspheres over 1 μm size

This study presents a robust and scalable method for synthesizing continuously the silica microspheres via the Stober method. Owing to the superb mixing accessible with gas-liquid segmented flow in coiled microtube, satisfactory morphology and mono-dispersity of silica spheres was obtained. The continuous method was firstly optimized through investigating the effects of various operation parameters on the morphology, particle size, size distribution and chemical structure of silica spheres. Without the surfactant, the size of silica spheres was limited < 850 nm due to the partial blockage of microchannel when synthesizing larger silica spheres. The addition of surfactant migrated the clogging issue, enabling the reliable synthesis of microspheres with diameters over 1 μm within a four times shorter residence time (30 min). Moreover, the mono-dispersity of silica microspheres could be further improved by increasing the gas/liquid ratio in segmented flow due to the more intensified mixing in liquid segments, as verified in visual flow field investigation.

Synthesis and experimental study of liquid dispersions of magnetic fluorescent polystyrene microspheres

Multiplex microsphere-based immunofluorescence assay is a reliable, accurate, and highly sensitive method for the detection of various biomolecules. However, for the moment, the wide application of the method in clinical practice is prevented by the high cost of reagents for analysis - magnetic spectrally encoded microspheres. Therefore, an urgent task is the development of new methods for the synthesis of microspheres with the required properties. The aim of this study was the creation of new magnetic fluorescent microspheres suitable for use in multiplex immunoassay.Samples of magnetic fluorescent polystyrene microspheres were synthesized by dispersion polymerization and two-stage swelling methods. Experimental studies of geometric parameters, fluorescence, magnetic properties of the synthesized microspheres have been carried out.The results of the studies have shown that microspheres synthesized by dispersion polymerization are promising for the use in immunofluorescence analysis. The obtained results can be used for the development of new diagnostic multiplex test systems based on spectrally encoded microspheres.

Synthesis and Study of the Composition of Hollow Microspheres of NiO and NiO/Ni Composition for Thermoelectrochemical Energy Converters of Low-Potential Temperature Gradients of Thermal Units Into Electricity

The article investigates the influence of the reduction modes of hollow nickel oxide microspheres synthesized by the pyrolysis of ultrasonic aerosols on the ratio of the oxide and metallic forms of nickel in their structure. The synthesis of microspheres from an aerosol of an aqueous solution of nickel nitrate was carried out; their composition and morphology were studied. The reduction of microspheres was carried out in a stream of hydrogen at different temperatures. The ratio of metallic nickel and oxide was determined by two different methods: according to the data of thermogravimetric analysis and by the Rietveld method based on the results of x-ray phase analysis. It is shown that the proportion of metallic nickel increases with an increase in the reduction temperature to approximately 375°C and then changes insignificantly. The fractional composition of microspheres was determined.

Influence of Ni / NiO Ratio on the Performance of Thermoelectrochemical Waste Heat Harvester Based on Hollow Microspheres

Technologies harvesting and converting the heat of low-temperature sources into electricity are one of the current trends in modern renewable energy. Thermoelectrochemical cells based on a nickel oxide electrode are gaining increasing popularity among researchers due to the high values of the hypothetical Seebeck coefficient. This work is devoted to the study of the reduction modes effect of hollow nickel oxide microspheres on the ratio of oxide and metal nickel forms in their structure. The paper presents the synthesis of microspheres by the pyrolysis of ultrasonic aerosols of an aqueous solution of nickel nitrate. Composition and morphology are studied by scanning electron microscopy and X-ray non-standard quantitative analysis. It was shown that the proportion of metallic nickel increases with an increase in the reduction temperature to about 375°C and then changes slightly. For microspheres, reduced at 350 °C, the main parameters of the thermoelectrochemical cell were determined. It was shown that the hypothetical Seebeck coefficient in the assembled cell system is 3.1 mV/K, and the resistance to charge transfer across the electrode-electrolyte interface was less than 1 Ohm. It confirms the applicability of these materials as electrodes for electrochemical systems and the possibility of obtaining high values of output power.

Using the ash of common water reeds as a silica source for producing high purity ZSM-5 zeolite microspheres

Abstract Utilizing of ash extracted from Iraqi common water reeds as an inexpensive effective silica source in the preparation of ZSM-5 zeolite was investigated for the first time in the present work. This study was conducted using a hydrothermal treatment at autogenous pressure. The molar content of silica (17.84–26.76), sodium oxide (1.71–2.4), water (76.92–304.6), organic template (0.55–2.73), organic solvent (23.46–140.76), and synthesis conditions (crystallization time (24–72 h) and temperature (130–180 °C)) were investigated to obtain high purity ZSM-5 zeolite microspheres. The zeolite samples were characterized using X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Energy Dispersive Analysis by X-Ray (EDAX), N2 adsorption/desorption isotherms, Thermogravimetric Analyzer (TGA), and Fourier transform infrared spectroscopy (FTIR). XRD pattern of all synthesized samples was compared to XRD pattern of the commercial ZSM-5 zeolite. This work allows using locally available solid waste resulted from a dry natural plant as an inexpensive silica source without using an external source of silica. Also, this is the first report of the direct synthesis of a high purity ZSM-5 zeolite microspheres from common water reeds ash containing highly reactive silica. A gel composition of 2Na2O: 26.76SiO2: Al2O3: 2.73TPAOH: 23.46EtOH: 304.6H2O gave an outstanding final product of ZSM-5 zeolite microspheres at 180 °C and 27 h. This high crystallinity ZSM-5 zeolite porous microspheres possess Si/Al ratio of 17, a crystal size of 61.419 nm, BET surface area of 277.482 m2/g, a total pore volume of 0.1659 cm3/g, micropore volume of 0.1131 cm3/g, pore width of 5.28 nm, and hierarchical factor of 0.14.

Facile synthesis of flower-like P-doped nickel-iron disulfide microspheres as advanced electrocatalysts for the oxygen evolution reaction

Although phosphosulfide and P-doped sulfide materials have been widely reported as highly efficient electrocatalysts for the oxygen evolution reaction (OER), the practical application of these materials is severely hindered by their complicated fabrication method. This paper reports a facile preparation of 3D hierarchical flower-like P-doped Ni–Fe disulfide microspheres by successive hydrothermal and one-step phosphosulfidation, using P2S5 as a source of phosphorus (P) and sulfur (S). Owing to the synergistic effect of the binary metal system, the introduction of P, and unique 3D porous architecture, the flower-like P-doped Ni–Fe disulfide microspheres deliver outstanding OER performance—an overpotential of 264 mV to achieve a current density of 10 mA cm−2, a significantly low Tafel slope of 48 mV dec−1, and excellent long-term durability over 50 h with negligible degradation in alkaline media. The fabrication method applied in this study can provide a new facile approach to the design and synthesis of P-doped metal sulfide materials for various electrochemical applications.