Photoluminescent BaMoO4 nanopowders prepared by complex polymerization method (CPM)

The BaMoO₄ nanopowders were prepared by the Complex Polymerization Method (CPM). The structure properties of the BaMoO₄ powders were characterized by FTIR transmittance spectra, X-ray diffraction (XRD), Raman spectra, photoluminescence spectra (PL) and high-resolution scanning electron microscopy (HR-SEM). The XRD, FTIR and Raman data showed that BaMoO₄ at 300 °C was disordered. At 400 °C and higher temperature, BaMoO₄ crystalline scheelite-type phases could be identified, without the presence of additional phases, according to the XRD, FTIR and Raman data. The calculated average crystallite sizes, calculated by XRD, around 40 nm, showed the tendency to increase with the temperature. The crystallite sizes, obtained by HR-SEM, were around of 40-50 nm. The sample that presented the highest intensity of the red emission band was the one heat treated at 400 °C for 2 h, and the sample that displayed the highest intensity of the green emission band was the one heat treated at 700 °C for 2 h. The CPM was shown to be a low cost route for the production of BaMoO₄ nanopowders, with the advantages of lower temperature, smaller time and reduced cost. The optical properties observed for BaMoO₄ nanopowders suggested that this material is a highly promising candidate for photoluminescent applications.     

含有BaMoO4纳米粒子的反胶束溶液与罗丹明B的相互作用

在三种带有不同电荷的表面活性剂构建的反胶束体系中(AOT/异辛烷、Oπ-10/环已烷、CTAB/正已醇)合成了BaMoO₄的纳米粒子, 采用透射电镜(TEM)观察其粒子呈球形, 粒径在17～46 nm范围内, 分布均匀; 使用染料罗丹明B作为探针, 采用紫外-可见光谱(UV-vis)和荧光光谱研究反胶束水池中罗丹明B与BaMoO₄纳米粒子的相互作用; 由于反胶束水池的空间和极性的限定, 染料的光谱特征与其在纯水中发生很大变化, 不同的反胶束体系中, 由于染料分子所处的微观环境不同, 导致其光谱特征也有较大区别.     

Preparation of FeS/iron oxide composite and flax stem‐based porous carbon and its Cr(VI) removal ability

Using flax stem and ferrous sulfate, a composite porous carbon material was prepared by means of high‐temperature roasting and a one‐step process in a muffle furnace. The samples were characterized using X‐Ray diffraction (XRD) and Scanning electron microscopy (SEM), and the effects of ferrous sulfate concentration, carbonization temperature, and pH values of Cr(VI) aqueous solution on the removal performance of Cr(VI) were studied. XRD and SEM analysis showed that the prepared samples were amorphous porous carbon loaded with FeS/Fe₂O₃/Fe₃O₄. High FeSO₄ impregnation concentration, high carbonization temperature, and a low pH value of Cr(VI) aqueous solution were beneficial for Cr(VI) removal. When pH = 2, the amount of Cr(VI) removal was 99.93 mg/g by the sample obtained from 1 g flax powder impregnated in 4.5 mmol FeSO₄/40 mL H₂O solution and calcined for 2 hr at 800°C.     

Morphology control and photocatalytic characterization of WO3 nanofiber bundles

WO₃ nanofiber bundles with high photocatalytic activity have been synthesized through the soluble salt-assisted hydrothermal method.     

A new sorbent for europium nitrate extraction: phosphonic acid grafted on polystyrene resin

A new chelating polymeric sorbent has been developed using polystyrene resin grafted with phosphonic acid. After characterization by FTIR and elementary analysis, the new resin has been investigated in liquid–solid extraction of europium(III). The results indicated that phosphonic resin could adsorb Eu(III) ion effectively from aqueous solution. The adsorption was strongly dependent on pH of the medium with enhanced adsorption as the pH value of 6.5. The influence of other analytical parameters including contact time, amount of resin, metal ion concentration, and ionic strength were investigated. The maximum uptake capacity of Eu(III) ions was 122.6 mg/g grafted resin at ambient temperature, at an initial pH value of 6.50. The overall adsorption process was best described by pseudo first-order kinetic. When Freundlich and Langmuir isotherms were tested, the latter had a better fit with the experimental data. Furthermore, Eu(III) could be eluted by using 1.0 mol/L H₂SO₄ solution and the grafted resin could be regenerated and reused.     

Evaluation of phosphate removal capacity of Fe<Subscript>3</Subscript>O<Subscript>4</Subscript>–ZVINPs from aqueous solution: optimization using response surface analysis

The present research aims to optimize the removal of phosphate (PO₄ ^3?) from aqueous solution by Fe₃O₄ stabilized zero-valent iron nanoparticles (Fe₃O₄–ZVINPs). A three-factor, three-level, Box–Behnken design combined with response surface methodology was applied to design the experiments, to develop a mathematical model, and for evaluating the individual and also the interactive effects of the operating variables like pH, temperature, and PO₄ ^3? concentration on removal efficiency. The analysis of variance has been used to evaluate the adequacy of the developed mathematical model in order to predict the optimal conditions of independent process variables, and to get maximum removal efficiency. Three-dimensional response surface plots were constructed to visualize the simultaneous interactive effects between two process variables. All three factors had a significant impact on removal of PO₄ ^3?. The predicted value of the model (166.0 mg g^?1PO₄ ^3?) was in good agreement with the experimental value (164.92 mg g^?1 PO₄ ^3?) under the optimum conditions of temperature 49.2 °C; pH 3.5; and PO₄ ^3? concentration 79.8 mg L^?1. The removal of PO₄ ^3? in the presence of environmental matrix (other ions) was also investigated at optimum conditions as predicted by the model. The results suggest that the presence of these ions had no significant effect on PO₄ ^3? removal. In addition, the adsorbed PO₄ ^3? can be effectively desorbed at higher pH of the solution. The findings suggest that removal of PO₄ ^3? from aqueous solution using Fe₃O₄–ZVINPs can be an effective method.     

Controlled Hydrothermal Synthesis and Structural Characterization of a Nickel Selenide Series

A series of nickel selenides (NiSe₂ microcrystals, Ni_1?xSe and Ni₃Se₂ microspheres) has been successfully synthesized through a convenient, low‐temperature hydrothermal method. A good nucleation and growth environment has been created by forming a uniform and transparent solution reaction system. The compositions (including the x value of Ni_1?xSe), phase structures, as well as the morphologies of nickel selenides, can be controlled by adjusting the Ni/Se ratio of the raw materials, the pH, the reaction temperatures and times, and so forth. The newly produced Se microspheres in the system have been used as both reactant and in situ template to the Ni_1?xSe microspheres. It is found that Ni_1?xSe microspheres act as the intermediate precursor during the formation of Ni₃Se₂ microspheres. Under certain conditions, hexagonal NiSe microspheres can be converted into rhombohedral NiSe nanowires in solution. The formation mechanisms of a series of nickel selenides has been investigated in detail by means of X‐ray diffraction (XRD) and scanning electron microscopy (SEM) analyses. This work has provided a general, simple, and effective method to control the composition, phase structure, and morphology of metal selenides in aqueous solution, which will be important for inorganic synthesis methodology and further applications of selenides.     

Sorption of U(VI) onto a decarbonated calcareous soil

Sorption of U(VI) from aqueous solution to decarbonated calcareous soil (DCS) was studied under ambient conditions using batch technique. Soil samples were characterized by XRD, FT-IR and SEM in detail and the effects of pH, solid-to-liquid ratio (m/V), temperature, contact time, fulvic acid (FA), CO₂ and carbonates on U(VI) sorption to calcareous soil were also studied in detail using batch technique. The results from experimental techniques showed that sorption of U(VI) on DCS was significantly influenced by pH values of the aqueous phase, indicating a formation of inner-sphere complexes at solid–liquid interface, and increased with increasing temperature, suggesting the sorption process was endothermic and spontaneous. Compared to Freundlich model, sorption of U(VI) to DCS was simulated better with Langmuir model. The sorption equilibrium could be quickly achieved within 5 h, and sorption results fitted pseudo-second-order model well. The presence of FA in sorption system enhanced U(VI) sorption at low pH and reduced U(VI) sorption at high pH values. In absence of FA, the sorption of U(VI) onto DCS was an irreversible process, while the presence of FA reinforced the U(VI) desorption process reversible. The presence of CO₂ decreased U(VI) sorption largely at pH >8, which might due to a weakly adsorbable formation of Ca₂UO₂(CO₃)₃ complex in aqueous phase.     

Photocatalytic and photoelectrocatalytic degradation of metoprolol tartrate in aqueous media by recyclable Co doping Fe<Subscript>3</Subscript>O<Subscript>4</Subscript>/TiO<Subscript>2</Subscript> magnetic core–shell nanocomposites

Magnetically recoverable cobalt doping Fe₃O₄/TiO₂ magnetic nanocomposites with an acceptable core–shell structure were prepared via a sol-gel process at low calcination temperature. The crystalline size and structure, morphology, and magnetic properties of resulting particles have been characterized by X-ray diffraction (XRD), fourier transform infrared (FT-IR), FT-Raman, high-resolution transmission electron microscopy (HRTEM), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), and vibrating sample magnetometry (VSM). Metoprolol tartrate (MET) as a pharmaceutical pollutant was used to observe the photocatalytic degradation ability of the magnetically recoverable particles. The process of degradation under UV irradiation at controlled temperature was studied and the remaining concentrations of MET as a contaminant were measured by UV-Vis spectrometer at λ = 229 nm. This ability remained 95.76% after three times of repetitive use at the same conditions. Various parameters such as reaction temperature, pH, and speed of stirring of the aqueous solution had an effect on the rate of degradation. The amount of cobalt dopant and nanocomposites are also effective on the rate of degradation. Coupling of electrical current with photocatalytic process has proven to be effective in the degradation of MET aqueous solution clearly.     

Facile synthesis of an optical sensor for CO32− and HCO3− detection

A novel fluorogenic signalling probe (E)-3-(4-methoxyphenyl)-4-[(4-nitrobenzylidene)amino]-1H-1,2,4-triazole-5(4H)-thione (6) for the carbonate and bicarbonate ions has been developed through microwave assisted Schiff base formation reaction. The anion recognition occurs through hydrogen bonding assessed by ¹H NMR titration experiments. The photophysical results of probe 6 corroborates its applicability as an optical sensing platform for carbonate as well as bicarbonate ions in mixed aqueous organic media depending on pH of reaction solution. The fluorescence emission signal enhancement at 424 nm and considerable shift in the signal position as well as molar absorptivity to the probe absorption bands upon CO₃^2? and HCO₃^? addition suggest the affinity of probe 6 towards these ions in comparison to a variety of competitive ions in aqueous/ethanol (7:3, v/v) at neutral pH and ambient temperature. From the fluorescence titration experiment, the limit of detection was calculated to be 1.91 μM.     

Hydrothermal Synthesis of Regular Octahedron Fe3O4 Microcrystals

Regular octahedron Fe₃O₄ microcrystals have been synthesized by a hydrothermal process on a large scale directly Fe substrates for the first time. X-ray diffraction (XRD) and scanning electron microscopy (SEM) have been used to investigate the novel fractal microcrystals. The results show that the regular octahedron Fe₃O₄ microcrystals can be obtained using this simple method. The size of microcrystals is evaluated to be from 2 to 20 μm. Moreover, one key fact has been found that the reaction temperature has a vital effect on the morphologies of the products.     

Preparation of Gold Microcrystal-Doped TiO2, ZrO2 and Al2O3 Films Through Sol-Gel Process

Au-microcrystal-doped TiO₂, ZrO₂ and Al₂O₃ films were made by sol-gel dip-coating method using titanium, zirconium and aluminum alkoxides with HAuCl₄ · 4H₂O. The influence of the oxide matrix composition on the maximum amount of the Au microcrystals that can be incorporated in the oxide film was examined. Some amount of Au microcrystals were exhausted to the surface of Au microcrystal-doped oxide films when an excess amount of HAuCl₄ · 4H₂O was dissolved in the coating solution. The maximum amount of Au that can be incorporated in the oxide film was found to increase with the increase of the pH point at zero charge (PZC) of the matrix oxide. This should be due to the fact that AuCl ₄ ^- ions are charged negative and also Au microcrystals tend to charge negative, so that the oxide gel with high PZC, which has a tendency to charge positive, may fix the ions and/or microcrystals to its interior. A maximum amount of Au microcrystals as high as 12.6 vol% was attained in an Au:Al₂O₃ film.     

Facile synthesis of calcium carbonate with an absolutely pure crystal form using 1-butyl-3-methylimidazolium dodecyl sulfate as the modifier

Calcium carbonate (CaCO₃) nanocrystals with controllable polymorph and morphology have been successfully synthesized with the aid of an effective control agent, a halogen-free, low-cost ionic liquid surfactant, 1-butyl-3-methylimidazolium dodecylsulfate ([C₄mim][C₁₂SO₄]) in a supersaturated aqueous solution. For the first time, facile preparation of pure lens-like vaterite, sheet-like calcite, and peanut-like aragonite was all achieved in the [C₄mim][C₁₂SO₄] aqueous solution through changing the concentration, temperature, and initial pH value and adding magnesium ions. Washed by water and ethanol, all the aggregates were free of [C₄mim][C₁₂SO₄] and can be stable at least 1 month in air. The crystal form of the aggregates changed from pure calcite to pure vaterite at room temperature only through increasing [C₄mim][C₁₂SO₄] concentration. Formation of the ordered CaCO₃ structures is mainly ascribed to the aggregation of the primary nanoparticles whose formation mechanism is related to the change of supersaturation. This study can provide a facile and environment-friendly method to fabricate CaCO₃ crystal aggregates with various morphologies and polymorphs and can be used for large-scale industrial production and biomimetic synthesis.     

不同形貌ZnO纳米粒子的超声化学法制备与表征

One-dimensional ZnO nanorods and shuttle-like ZnO nanoparticles have been successfully achieved by ultrasonic irradiation of Zn (CH3COO)2 aqueous solution and Zn-NH3 complexcs solution. The obtained ZnO nanoparticles have been characterized using X-ray diffraction (XRD), transmission electron microscopy (TEM) and selected area electronic diffraction (SAED). And the formative mechanism of the prepared different morphological ZnO nanoparticles is also discussed under ultrasonic irradiation.     

Aspects of Degradation Kinetics of Azithromycin in Aqueous Solution

The chemical stability of azithromycin (AZM) in aqueous solution has been investigated utilizing a stability-indicating LC assay with ultraviolet detection. The degradation kinetics were studied as functions of pH (4–7.2), buffer composition (phosphate, acetate, and citrate), buffer concentration, ionic strength, drug concentration and temperature. The observed rate obtained by measuring the remaining intact AZM was shown to follow pseudo-first-order kinetics. The maximum stability of AZM occured at an approximate pH 6.3 in 0.05 M potassium phosphate. The observed degradation rate increased with ionic strength, buffer concentration and obeyed the Arrhenius equation over the temperature range investigated (70–100 °C). The apparent energy of activation (E _a) for AZM in solution was found to be 96.8 kJ mol^?1 and by application of the Arrhenius equation the stability at 25 °C (k ₂₅) and 40 °C (k ₄₀) had been predicted. Moreover, the degradation rate of AZM was independent on its initial concentration. Trace metal ions are unlikely to be involved in the degradation of AZM in aqueous solution. The major degradation product of AZM in aqueous solution was isolated and identified by LC–MS–MS and ¹H and ¹³C NMR spectra.     

The effect of cerium pre-treatment on the corrosion resistance of steel sheets

The steel samples have been coated with cerium layer by cathodic electrolytic deposition from the Ce(NO₃)₃·6H₂O solution in aqueous ethyleneglycol in the presence of hydrogen peroxide. The influence of the coating parameters (cathodic current density, pH, cerium concentration, hydrogen peroxide concentration, temperature, and treatment duration) on the surface properties; the optimum conditions of the formation of corrosion preventing coating have been elucidated. Hydrogen peroxide concentration and pH are the major factors influencing the deposition process. The corrosion resistance has been further enhanced after treatment with Na₃PO₄·12H₂O solution. The cerium-coated samples have been subsequently coated by cathodic electrostatic deposition from the colloidal solution of the paint. The coated materials have been subjected to mechanical testing (hardness, impact, cross cut, bending, and cupping tests), and their structure has been visualized by electron microscopy. The cerium coating has been found to improve the steel corrosion resistance by 15%.     

Characterization of the transient species generated by the photoionization of Berberine: A laser flash photolysis study

Using 266 nm laser flash photolysis it has been demonstrated that Berberine (BBR) in aqueous solution is ionized via a mono-photonic process giving a hydrated electron, anion radical that formed by hydrated electron react with steady state of BBR, and neutral radical that formed from rapid deprotonation of the radical cation of BBR. The quantum yield of photoionization is determined to be 0.03 at room temperature with KI solution used as a reference. Furthermore utilizing pH changing method and the SO₄⁻ radical oxidation method, the assignment of radical cation of BBR was further confirmed, the pK_a value of it was calculated, and the related set up rate constant was also determined.     

Chemical degradation of poly(2-aminoethyl methacrylate)

Poly(2-aminoethyl methacrylate) (PAMA) has a pK_a of approximately 7.6 and is chemically stable in acidic or neutral aqueous solution in its protonated form. However, chemical degradation of PAMA is known to occur in alkaline media as its primary amine groups become deprotonated (He L et al. Macromolecules 2007; 40: 4429-38). In the present work, the effect of temperature, pH and polymer concentration on the rate of PAMA degradation in dilute aqueous solution has been examined. ¹H NMR spectroscopy indicates that both elimination of 2-aminoethanol and formation of 2-hydroxyethyl methacrylamide repeat units occur above pH 9; elimination is observed first and occurs to a greater extent. FT-IR studies of aqueous PAMA solutions aged at pH 12 and 50 °C confirm the presence of anionic carboxylate groups, which suggests that such elimination is simply due to ester hydrolysis. A control experiment suggests that methacrylamide formation occurs via internal rearrangement, rather than by amidation of the remaining ester groups by the eliminated 2-aminoethanol.     

Structural characterization and electrical conductivity studies of BaMoO4 nanofibers prepared by sol–gel and electrospinning techniques

Scheelite type BaMoO₄ nanofibers were prepared by using acrylamide assisted sol–gel process and electrospinning technique. The prepared Scheelite BaMoO₄ nanofibers were characterized by using TG/DTA, XRD, FTIR, FT-Raman and SEM–EDX techniques. Thermal behavior, crystalline phase and structure of the prepared BaMoO₄ nanofibers samples were confirmed from the analysis of the obtained results of TG/DTA, XRD, FTIR and FT-Raman respectively. SEM micrographs along with EDX showed the formation of one dimensional (1D) nanofibers 100–350 nm diameters and existence of Ba, Mo and O elements in the BaMoO₄ nanofibers sample. The electrical conductivity of BaMoO₄ nanofibers as a function of temperature 200–400 °C under air was evaluated by analyzing the measured impedance data using the winfit software. The newly prepared Scheelite type BaMoO₄ nanofibers showed electrical conductivity of 0.92 × 10^?3 S/cm at 400 °C.     

Debromination of 2,4,6-tribromophenol coupled with biodegradation

The application effect of aluminium and their alloys and mixtures with nickel was studied for the complete hydrodebromination of 2,4,6-tribromophenol (TBP) to phenol in aqueous NaOH solution at room temperature. It was found that the Raney Al-Ni alloy can rapidly transform TBP to phenol. Removal efficiency of 25 mM TBP solution in aqueous NaOH (15 g L^?1) solution at the end of 1h reaction was 100% using 4 g L^?1 Al-Ni. The hydrodebromination is accompanied by the dissolution of aluminium and formation of soluble Al(OH)₄ ^?1 anions under these reaction conditions. After completion of the hydrodebromination reaction removal of the dissolved metals was achieved by precipitation of appropriate hydroxides by adjustment of the pH value and filtration, the filtrate was treated with Pseudomonas or Rhodococcus bacterial strains to degrade dissolved phenol. The combined application of both (chemical-biological) treatments produced degradations of 100% of aromatic compounds.