Catalytic activity of Au/Fe-PILC and Au/Fe-oxide catalysts for catalytic combustion of formaldehyde

Iron polymeric hydroxygroups pillared clays （Fe-PILC） were prepared by Na^＋-montmorillonite with iron pillaring agent. 2.01Au/Fe-PILC catalyst was obtained by deposited-precipitation （DP） method. 2.52Au/Fe-oxide catalyst was prepared by co-precipitation method. The catalytic activity of these catalysts was measured by catalytic combustion of formaldehyde. The catalyst of 2.01Au/Fe-PILC exhibits the high catalytic activity. The catalytic combustion reaction of formaldehyde proceeds at considerable rates at 20 ℃ and complete burn-off of formaldehyde is achieved at 120 ℃. The structure of catalysts, the valence state of gold and the size of gold particles were investigated by means of X-ray powder diffractometry, X-ray photoelectron spectroscopy and transmission electron microscopy. The results show that gold atoms with partially positive charge exist in the catalyst and play an important role in the catalytic activity. In addition, nano-sized, well-dispersed gold particles and good adsorption properties of support are necessary to obtain high activity Au catalysts for catalytic combustion of formaldehyde.     

Effects of gold plating on the resistance to high temperature discoloration of the cavity for ceramic packages

The effects of thickness and types of gold plating on the resistance to high temperature discoloration of gold plating on cavity surface of ceramic package were investigated. It was found that the thicker gold plating, the less discoloration degree for ceramic packages. Non-cyanide gold plating performed better resistance to high-temperature aging than cyanide gold plating. The relationship between the gold plating thickness and the amount of diffused Ni to the gold plating of ceramic packages with Au/Ni and Au/Ni-Co platings after heating at 420℃for 15 min was also studied. When the gold plating thickness reach 2.0 μm and 1.6 μm for Au/Ni and Au/Ni-Co plating systems, respectively, no discoloration was observed on the gold plating surface of cavity, and the corresponding diffused Ni amounts (mass fraction) are 1.0% and 0.4%, while the diffused Co to the gold plating is 0.04%.     

Cloud point extraction and flame atomic absorption spectrometry analysis of palladium, platinum, and gold ions from industrial polluted soil

Cloud point extraction (CPE) with Tergitol TMN-6 was applied for the extraction of trace amounts of palladium (Pd(Ⅱ)),platinum (Pt(Ⅳ)),and gold (Au(Ⅲ)) in the soil of industrial sewage.Ammonium pyrolysine dithiocarbamate (APDC) was adopted as the chelating agent prior to CPE and then was detected by atomic absorption spectrometry (AAS).Different parameters such as the concentration of surfactants,chelating agent and salt,sample pH,equilibration temperature and time,centrifugation time and rates,and the effect of foreign ions were studied.Under optimum conditions,the low limits of detections are 1.4,2.8 and 1.2 ng.ml-1 and the enrichment factors are 21,12,and 24 for Pd(Ⅱ),Pt(Ⅳ),and Au(Ⅲ),respectively.The relative standard deviations vary from 0.6％ to 1.0％ (n=11).All correlation coefficients of the calibration curves are ＞0.9960.The proposed method was successfully applied for the determination of Pd(Ⅱ),Pt(Ⅳ),and Au(Ⅲ) in the real soil of industrial sewage samples.     

Removal of Co(Ⅱ) from aqueous solutions by NKC-9 strong acid resin

A strong acidic ion exchange resin(NKC-9)was used as a new adsorbent material for the removal of Co(Ⅱ)from aqueous solutions.The adsorption isotherm follows the Langmuir model.The maximum adsorption capacity of the resin for Co(Ⅱ)is evaluated to be 361.0 mg/g by the Langmuir model.It is found that 0.5 mol/L HCl solution provides effectiveness of the desorption of Co(Ⅱ)from the resin.The adsorption rate constants determined at 288,298 and 308 K are 7.12×10-5,8.51×10-5and 9.85×10-5s-1, respectively.The apparent activation energy(Ea)is 12.0 kJ/mol and the adsorption parameters of thermodynamic are-H Θ=16.1 kJ/mol,-SΘ=163.4 J/(mol·K),-G Θ 298 K=-32.6 kJ/mol,respectively.The adsorption of Co(Ⅱ)on the resin is found to be endothermic in nature.Column experiments show that it is possible to remove Co(Ⅱ)ions from aqueous medium dynamically by NKC-9 resin.     

Extraction and separation of Fe(Ⅲ) from heavy metal wastewater using P204 solvent impregnated resin

The extraction and separation of Fe(Ⅲ) from heavy metal wastewater generated in zinc smelting process were studied using solvent impregnated resin containing CLP204. The influence of pH and temperature on absorbing heavy metal cations by static adsorption was investigated.The batch tests on adsorption equilibrium, kinetics and elution efficiency were carried out to evaluate the performance of CL-P204. Column operations for extraction and separation of Fe(Ⅲ) by CL-P204 were performed for further optimization of process parameters and feasibility evaluation. The reaction mechanism of Fe(Ⅲ) and CL-P204 was analyzed through saturation capability, slope analysis and infrared spectroscopy (IR). The results show that the separation of Fe(Ⅲ) from heavy metal wastewater using CLP204 can be achieved through process of adsorption and desorption at a flow rate of 1.53 ml·min~(-1)·cm~(-2), pH 0.8 and temperature of 25℃. The experimental data of Fe(Ⅲ)adsorption by CL-P204 have a satisfactory fit with Langmuir adsorption equation and Freundlich adsorption isotherms.The probable molecular formula of extracted complex is Fe[R_2(R_2H)],and the adsorption reaction equation is concluded as following:Fe~(3+)+4RH K_(ex)Fe[R_2(R_2H)]+3H~+(K_(ex), extraction equilibrium constant). This study will supply the fundamentals for treatment of heavy metal wastewater.     

Superparamagnetic CoFe_2O_4@Au with High Specific Absorption Rate and Intrinsic Loss Power for Magnetic Fluid Hyperthermia Applications

CoFe_2O_4 nanoparticles(NPs) and surface modified with gold(Au) have been synthesized by a thermal decomposition method. The obtained NPs and formation of CoFe_2O_4@Au core–shell(CS) were confirmed by characterizing their structural and optical properties using X-ray powder diffraction(XRD) patterns, Fourier transform infrared spectroscopy,Raman spectroscopy, UV–Visible and photoluminescence studies. Morphological and compositional studies were carried out using high-resolution transmission electron microscopy and energy-dispersive X-ray spectroscopy, while the magnetic properties were determined using alternating gradient magnetometer and Mossbauer to define the magneto-structural effects of shell formation on the core NPs. Induction heating properties of CoFe_2O_4 and CoFe_2O_4@Au CS magnetic nanoparticles(MNPs) have been investigated and correlated with magneto-structural properties. Specific absorption rate and intrinsic loss power were calculated for these MNPs within the human tolerable range of frequency and amplitude,suggesting their potential in magnetic fluid hyperthermia therapy for possible cancer treatment.     

Electroless Ni-Co-P Coating of Cenospheres Using Ag（NH3）2^＋ Activator

Electroless Ni-Co-P-coating of fly-ash cenosphere particles is demonstrated in the present investigation. The Electroless Ni-Co-P-coating process is modified by replacing the conventional sensitization and activation steps with only using activation step with Ag(NH3)2^ activator. The cenospheres are characterized by scanning electron microscope (SEM), energy dispersive spectroscopy (EDX), X-ray diffraction analysis (XRD) and X-ray photoelectron spectroscopy (XPS) during and after the coating process. Relatively uniform coating is obtained under the given coating conditions. The possible mechanism of electroless Ni-Co-P-coating of cenospheres utilizing Ag(NH3)2^ activator is suggested. The low density Ni-Co-P coated cenospheres may be utilized for manufacturing conducting polymers for EMI-shielding application and microwave absorbing materials.     

Kinetic and thermodynamic studies of adsorption of gallium(Ⅲ) on nano-TiO_2

Nano-TiO2 was employed for the adsorption of gallium from aqueous solution in batch equilibrium experiments to investigate its adsorption properties. It was found that the adsorption efficiency of Ga(Ⅲ) was more than 96% at pH 3.0. The adsorption capacities and rates of Ga(Ⅲ) onto nano-TiO2 were evaluated as a function of solution concentration and temperature. The results were analyzed using the Langmuir adsorption isotherms. Adsorption isothermal data could be well interpreted by the Langmuir model. The mean energy of adsorption, 15.81 kJ·mol-1, was calculated from the D-R adsorption isotherm. The kinetic experimental data properly correlate with the pseudo-second-order kinetic model. The thermodynamic parameters for the process of adsorption have been estimated. The △ H Οand △ GΟvalues of gallium(Ⅲ) adsorption on nano-TiO2 showed an endothermic and spontaneous nature of adsorption.     

Electrocatalytic oxidation of methanol on carbon-nanotubes/graphite electrode modified with platinum and molybdenum oxide nanoparticles

Electrochemical codeposition and electrocatalytic properties of platinum and molybdenum oxide nanoparticles(Pt-MoOx) on carbon-nanotubes/graphite electrode for methanol oxidation were investigated.The micrograph and elemental composition of the resulting Pt-MoOx/CNTs/graphite electrode were characterized by scanning electron microscopy(SEM)and energy dispersive X-ray spectroscopy(EDS).The results show that the Pt-MoOx particles with the average size of about 50 nm are highly dispersed on the CNTs surface.The Pt-MoOx/CNTs/graphite electrode delivers excellent electrocatalytic properties for methanol oxidation.The highest mass activity(Am)reaches 264.8 A/g at the loading mass of 159.3μg/cm2.This may be attributed to the small particle size and high dispersion of Pt-MoOx catalysts deposited on the CNTs surface.The kinetic analysis from electrochemical impedance spectroscopy(EIS)reveals that the existed MoOx phase can improve the chemisorptive and catalytic properties for methanol oxidation.     

Solvothermal synthesis of nano-CeO_2 aggregates and its application as a high-efficient arsenic adsorbent

Aggregates of cerium dioxide nanoparticles(nano-CeO_2) were successfully prepared via a facile solvothermal process in this study. The crystallographic information and morphological information of nano-CeO_2 were systematically studied by X-ray diffraction(XRD),transmission electron microscopy(TEM), laser particle size analyzer(LA) and specific surface area and pore size analyzer during the solvothermal process. Among all the obtained samples, the 18-h solvothermal-prepared nano-CeO_2 aggregates show the best crystallinity and the largest specific surface area of 110.92 m~2·g~(-1). Owing to the high activity derived from the high specific surface area of the aggregates, the application as arsenic(As) adsorption was also studied. The adsorption efficiency of arsenic by nano-CeO_2 aggregates was established as the function of adsorbent dose, then pH value and at last adsorption time.The results indicate that the nano-CeO_2 aggregates show a high efficiency in removing arsenic from low As concentration solution, from which the nano-CeO_2 adsorbent could be easily separated. In addition, the adsorption kinetics is best fitted to pseudo-second-order model(R~2 = 0.99999).     

Kenaf cellulose-based poly(amidoxime) ligand for adsorption of rare earth ions

A well-known adsorbent, poly(amidoxime)ligand, was prepared from polyacrylonitrile(PAN) grafted kenaf cellulose, and subsequent characterization was performed by Fourier transform infrared spectroscopy(FTIR),field emission scanning electron microscope(FESEM) and inductively coupled plasma mass spectrometry(ICP-MS).The adsorption capacities of the prepared ligand for rare earth metals are found to be excellent, with adsorptions of La~(3+), Ce~(3+), Pr~(3+), Gd~(3+) and Nd~(3+) experimentally determined to be 262, 255, 244, 241 and 233 mg·g~(-1), respectively, at pH 6. The experimental values of the adsorption of rare earth metals are well matched with the pseudosecond-order rate equation. The reusability of the adsorbent is examined for seven cycles of sorption/desorption,demonstrating that the proposed adsorbent could be reused for over seven cycles without any significant loss in the original removal capability of the ligand.     

Separation of indium (Ⅲ), gallium (Ⅲ), and zinc (Ⅱ) with Levextrel resin containing di(2-ethylhexyl) phosphoric acid (CL-P204): Part I. Selection of separation conditions

A kind of Levextrel resin separation process was developed for separation of indium (Ⅲ), gallium (Ⅲ), and zinc (Ⅱ) from aqueous sulfate solution with Levextrel resin containing di(2-ethylhexyl) phosphoric acid (CL-P204). The aim of the research is to collect preliminary results for a pilot-scale production. Properties of adsorbing indium (Ⅲ), gallium (Ⅲ), and zinc (Ⅱ) from sulfate solution with the Levextrel resin were first studied by batch operation and column operation. The optimum pH, adsorption capacities and concentrations of stripping agents for indium (Ⅲ), gallium (Ⅲ) were tested. The separation order of indium (Ⅲ), gallium (Ⅲ), and zinc (Ⅱ) from sulfate solution with CL-P204 Levextrel resin was found that indium (Ⅲ) could be first separated by adsorbing at the acidity of 1.0 mol/L whereas gallium (Ⅲ) and zinc (Ⅱ) could not, and they were adsorbed together by adsorbing at pH = 2.8, then separated from each other by stripping with 0.1 and 0.5 mol/L hydrochloric acid, respectively. T     

Separation of indium(Ⅲ),gallium (Ⅲ),and zinc(Ⅱ)with Levextrel resin containing di(2-ethylhexyl)phosphoric acid(CL-P204):Part Ⅰ. Selection of separation conditions

A kind of Levextrel resin separation process was developed for separation of indium (Ⅲ), gallium (Ⅲ), and zinc (Ⅱ) from aqueous sulfate solution with Levextrel resin containing di(2-ethylhexyl) phosphoric acid (CL-P204). The aim of the research is to collect preliminary results for a pilot-scale production. Properties of adsorbing indium (Ⅲ), gallium (Ⅲ),and zinc (Ⅱ) from sulfate solution with the Levextrel resin were first studied by batch operation and column operation. The optimum pH, adsorption capacities and concentrations of stripping agents for indium (Ⅲ), gallim (Ⅲ) were tested. The separation order of indium (Ⅲ), gallim (Ⅲ), and zinc (Ⅱ) from sulfate solution with CL-P204 Levextrel resin was found that indium (Ⅲ) could be first separated by adsorbing at the acidity of 1.0 mol/L whereas gallium (Ⅲ) and zinc (Ⅱ) could not, and they were adsorbed together by adsorbing at pH = 2.8, then separated from each other by stripping with 0.1 and 0.5mol/L hydrochloric acid, respectively. The recoveries of three metal ions were all higher than 99%. The cyclic properties of this resin are well.     

Solid-phase extraction of trace Au(Ⅲ) with SDG and determination by the catalytic spectrophotometric method

The new catalytic kinetic spectrophotometric method for Au(Ⅲ) determination was developed and validated.It was based on the catalytic effect of gold on the oxidation of sudan red Ⅲ by ammonium peroxodisulfate ((NH4)2S2O8) with nitrilo triaeetic acid as an activator in microemulsion and H2SO4 medium.Under optimum conditions,there was the linearity of the calibration curve in the concentration range from 0 to 20 μg/L Au(Ⅲ) at 520 nm.The relative standard deviation was 3.0% with a correlation coefficient of 0.9986.The detection limit achieved was 9.75×10-5 μg/mL.A new method using a column packed with sulfhydryl dextrose gel (SDG) as a solid-phase extraetant has been developed for the preeoncentration and separation of Au(Ⅲ) ions.The method has been applied to the determination of trace gold with satisfactory results.     

Synergetic effect of BiOCl/Bi_(12)O_(17)Cl_2 and MoS_2: in situ DRIFTS investigation on photocatalytic NO oxidation pathway

The BiOCl/Bi_(12) O_(17) Cl_2@MoS_2(BOC-MS)composites were successfully synthesized by a facile method at room temperature. The physicochemical properties of the as-obtained samples were characterized by X-ray diffractometer(XRD), scanning electron microscopy(SEM), transmission electron microscopy(TEM), X-ray photoelectron spectroscopy(XPS), ultraviolet–visible diffuse reflection spectra(UV–Vis DRS), photoluminescence(PL), Brunauer–Emmett–Teller–Barrett–Joyner–Halenda(BET–BJH), and electron spin resonance(ESR) in detail.Moreover, the in situ diffuse reflectance infrared Fourier transform spectroscopy(DRIFTS) was applied to elucidate the adsorption and photocatalytic reaction mechanism. The optimized BOC-MS-1.0 composites exhibited excellent visible light photocatalytic capability(51.1%) and photochemical stability for removal of NO. Based on the DMPOESR spin trapping, the áO_2-radicals and áOH radicals were identified as the main active species generated from BOCMS-1.0 under visible light irradiation. The enhanced photocatalytic performance can be ascribed to the positive synergetic effect of the MoS_2 and the effective carrier separation ability.     

Synthesis of vanadium and chromium carbides(V_8C_7–Cr_3C_2) nanocomposite via an in situ precursor method

In situ synthesis method was used to prepare V8C7–Cr3C2nanocomposite.Ammonium vanadate, ammonium dichromate and nanometer carbon black were used as raw materials.The products were characterized by X-ray diffractometry(XRD), scanning electron microscopy(SEM), transmission electron microscopy(TEM), thermogravimetric and differential scanning calorimetry(TGDSC) and X-ray photoelectron spectroscopy(XPS) techniques.The results show that V8C7–Cr3C2nanocomposite with an average crystallite size of 25.4 nm can be synthesized at 1200 °C for 1 h.The synthesis temperature required by the method is at least 200 °C lower than that required by the conventional approaches for preparing vanadium and chromium carbides.The powders show good dispersion and are mainly composed of spherical or nearly spherical particles with a mean diameter of about 30 nm.The weight loss ratio of the precursor throughout the reaction process reaches 58 wt%.Three exothermic peaks and four endothermic peaks occur during the reaction.The surface of the specimen is mainly composed of V, Cr, C and O elements.     

Rauvolfia serpentina-Mediated Green Synthesis of CuO Nanoparticles and Its Multidisciplinary Studies

Copper oxide nanoparticles(Cu O Nps) were successfully synthesized by solution combustion method using aqueous leaf extract of Rauvolfia serpentina as a fuel. The structure and morphology of the Cu O nanoparticles(Nps) were characterized by powder X-ray diffraction(PXRD), UV–visible spectroscopy(UV–visible), scanning electron microscopy(SEM), transmission electron microscopy(TEM), etc. The PXRD patterns reveal the formation of monoclinic phase with crystallite structure. SEM images indicate that the particles have sponge-like structure being highly porous and agglomerated with large surface area. The average crystallite sizes were found to be in the range of 10–20 nm by Scherrer's method. The Cu O Nps size was further confirmed by TEM. Further, Cu O Nps exhibit good photocatalytic activity for the photodegradation of trypan blue dye, indicating that it acts as a promising semiconducting material. The antibacterial properties of Cu O nanoparticles were investigated against pathogenic bacterial strains, namely Gram-ve Escherichia coli(NCIM-5051) and Pseudomonas desmolyticum(NCIM-2028) and Gram ?ve bacteria Staphylococcus aureus(NCIM-5022) using the agar well diffusion method.     

Characterization of CeO_2 microspheres fabricated by an ultrasonic spray pyrolysis method

CeO_2 is one of the main catalysts for solid oxide fuel cell(SOFC).It is critical to find a green and costeffective fabrication method for CeO_2 at scale.In this study,the CeO_2 microspheres were prepared by one-step ultrasonic spray pyrolysis of cerium chloride solution at700℃.Scanning electron microscopy(SEM) and transmission electron microscopy(TEM) study demonstrate that the prepared CeO_2 microspheres exhibit a particle size of0.01-1.08 μm with a mean particle size of 0.23 μm,and more than 94% of the particles have a diameter less than0.5 μm.But the presence of residual Cl in the fabricated CeO_2 microspheres blocks the active sites and leads to the significant degradation of SOFC performance.The formation mechanism and distribution of residual Cl in the fabricated CeO_2 microspheres were systemic ally studied.The water washing method was shown to effectively reduce the residual Cl in the CeO_2 microspheres.Overall,this work provides a clean manufacturing process for the preparation of SOFC electrode/electrolyte materials.     

Dehydrogenation characteristics of ZrC-doped LiAlH_4 with different mixing conditions

The catalytic effects of ZrC powder on the dehydrogenation properties of LiAlH_4 prepared by designed mixing processes were systematically investigated.The onset dehydrogenation temperatures for the 10 mol% ZrC-doped sample are 85.3 and 148.4℃for the first two dehydrogenation stages,decreasing by 90.7 and 57.8℃,respectively,compared with those of the as-received LiAIH_4.The isothermal volumetric measurement indicates that adding ZrC powder could significantly enhance the desorption kinetics of LiAlH_4.The reaction constant and Avrami index show that the first dehydrogenation stage is controlled by diffusion mechanism with nucleation rate gradually decreasing and the second stage is a freedom nucleation and subsequent growth process.The microstructures and phase transformation characterized by scanning electron microscopy(SEM),X-ray diffraction(XRD),X-ray photoelectron spectroscopy(XPS) and Fourier transform infrared spectroscopy(FTIR) reveal that the improved desorption behavior of LiAlH_4 is primarily due to the high density of surface defects and embedded catalyst particles on the surface of LiAlH_4 particles during the high-energy mixing process.     

Preparation of micro-nano hollow multiphase ceramic microspheres containing MnFe2O4 absorbent by self-reactive quenching method

Fe–Fe2O3–MnO2–sucrose–epoxy resin and O2 as reaction system and feed gas,separately,were used to prepare micro-nano hollow multiphase ceramic microspheres containing MnFe2O4absorbent by self-reactive quenching method which is integrated with flame jet,selfpropagating high-temperature synthesis(SHS),and rapidly solidification.The morphologies and phase compositions of hollow microspheres were studied by scanning electron microscope(SEM),transmission electron microscope(TEM),X-ray diffraction(XRD),and energy dispersive spectroscopy.The results show that the quenching products are regular spherical substantially with hollow structure,particle size is between few hundreds nanometers and 5 lm.Phase compositions are diphase of Fe3O4,Mn3O4,and MnFe2O4,and the spinel soft magnetic ferrite MnFe2O4 with microwave magnetic properties is in majority.Collisions with each other,burst as well as‘‘refinement’’of agglomerate powders in flame field may be the main reasons for the formation of micro-nano hollow multiphase ceramic microspheres containing MnFeOabsorbent.