Enhanced Photoactivity of Layered Nanocomposite Materials Containing Rare Earths,Titanium Dioxide and Clay

The nanocomposite materials containing rare earths, titanium dioxide and clay (RE/TiO2/Clay) were characterized and tested for the photocatalytic decomposition of formaldehyde. The results show that nanocomposite materials prepared by doping appropriate rare earth elements have better photocatalytic properties than that prepared by doping excessive rare earth elements. The photocatalytic mechanism of composite materials was studied by integrating the theory of pho-tocatalysis with experiment results. Because the site of photocatalytic reaction was limited in the interspace of clay, photocatalytic reaction occurred by two steps: firstly, organic molecules dispersed into the interlayers of clay; secondly, organic molecules and photocatalyst of RE/TiO2 occurred photocatalytic reaction, resulting in forming carbon dioxide.

Determination of Triclocarban, Triclosan and Methyl-Triclosan in Environmental Water by Silicon Dioxide/Polystyrene Composite Microspheres Solid-Phase Extraction Combined with HPLC-ESI-MS

This paper developed a sensitive and efficient analytical method for triclocarban (TCC), triclosan (TCS) and Methyl-triclosan (MTCS) determination in environmental water, which involves enrichment by using silicon dioxide/polystyrene composite microspheres solid-phase extraction and detection with HPLC-ESI-MS. The influence of several operational parameters, including the eluant and its volume, the flow rate and acidity of water sample were investigated and optimized. Under the optimum conditions, the limits of detection were 1.0 ng/L, 2.5 and 4.5 ng/L for TCC, TCS, and MTCS, respectively. The linearity of the method was observed in the range of 5-2000 ng/L, with correlation coefficients (r2) >.99. The spiked recoveries of TCC, TCS and MTCS in water sampleswereachieved in the range of 89.5% -96.8% with RSD below 5.7%. The proposed method has been successfully applied to analyze real water samples and satisfactory results were achieved.

Preparation and Characterization of CA-MA Eutectic/Silicon Dioxide Nanoscale Composite Phase Change Material from Water Glass via Sol-Gel Method

This work mainly involved the preparation of a nano-scale form-stable phase change material（PCM） consisting of capric and myristic acid（CA-MA） binary eutectic acting as thermal absorbing material and nano silicon dioxide（nano-SiO_2） serving as the supporting material. Industrial water glass for preparation of the nano silicon dioxide matrix and CA-MA eutectic mixture were compounded by single-step sol-gel method with the silane coupling agent. The morphology, chemical characterization and form stability property of the composite PCM were investigated by transmission electron microscopy（TEM）, scanning electron microscopy（SEM）, Fourier-transform infrared（FT-IR） spectroscopy and polarizing microscopy（POM）. It was indicated that the average diameter of the composite PCM particle ranged from 30-100 nm. The CA-MA eutectic was immobilized in the network pores constructed by the Si-O bonds so that the composite PCM was allowed no liquid leakage above the melting temperature of the CA-MA eutectic. Differential scanning calorimetry（DSC） and thermogravimetric analysis（TGA） measurement were conducted to investigate the thermal properties and stability of the composite PCM. From the measurement results, the mass fraction of the CA-MA eutectic in the composite PCM was about 40%. The phase change temperature and latent heat of the composite were determined to be 21.15 ℃ and 55.67 J/g, respectively. Meanwhile, thermal conductivity of the composite was measured to be 0.208 W·m^（-1）·K^（-1） by using the transient hot-wire method. The composite PCM was able to maintain the surrounding temperature close to its phase change temperature and behaved well in thermalregulated performance which was verified by the heat storage-release experiment. This kind of form-stable PCM was supposed to complete thermal insulation even temperature regulation by the dual effect of relatively low thermal conductivity and phase change thermal storage-release properties. So it can be formulated that the nanoscale CA-MA/SiO_2 composite PCM with the form-stable property, good thermal storage capacity and relatively low thermal conductivity can be applied for energy conservation as a kind of thermal functional material.

Electrosynthesis and physicochemical properties ofα-PbO_2-CeO_2-TiO_2 composite electrodes

In order to investigate the effect of solid particles dopants on physicochemical properties of α-PbO2 electrodes, a-PbO2 composite electrodes doped with nano-TiO2 and nano-CeO2 particles were respectively prepared on A1/conductive coating electrodes in 4 mol/L NaOH solution with addition of PbO until saturation by anodic codeposition. The electrodeposition mechanism, morphology, composition and structure of the composite electrodes were characterized by cyclic voltarnmogram （CV）, SEM, EDAX and XRD. Results show that the doping solid particles can not change reaction mechanism of α-PbO2 electrode in alkaline or acid plating bath, but can improve deposition rate and reduce oxygen evolution potential. The doping solid particles can inhibit the growth of a-PbO2 unit cell and improve specific surface area. The diffraction peak intensity of a-PbO2-CeO2-TiO2 composite electrode is lower than that of pure a-PbO2 electrode. The electrocatalytic activity of a-PbO2-2.12%CEO2-3.71%TIO2 composite electrode is the best. The Guglielmi model for CeO2 and TiO2 codeposition with a-PbO2 is also pronosed.

Photocatalytic Degradation of Phenol over MWCNTs-TiO2 Composite Catalysts with Different Diameters

Titania-based composite catalysts were prepared through a sol-gel route employing multi-walled carbon nanotubes with different diameters. The materials were characterized using thermogravimetric analysis, nitrogen adsorption-desorption isotherm, powder X-ray diffraction, scanning electron microscopy, and diffuse reflectance UV-Vis absorption spectra. The application of the catalysts to photocatalytic degradation of phenol was tested under UV-Vis irradiation. A synergetic effect on phenol removal was observed in case of composite catalysts, which was evaluated in terms of apparent rate constant, total organic carbon removal and photonic efficiency.

Effect of composition and sintering temperature on mechanical properties of ZrO_2 particulate-reinforced titanium-matrix composite

The titanium-based composites were synthesized by powder metallurgy method. The effects of composition and sintering temperature on the microstructure and properties of the titanium-based composites were investigated by X-ray diffraction, optical microscopy, scanning electron microscopy and mechanical properties tests. The results demonstrate that adding ZrO2 particles can improve the mechanical properties of powder metallurgy （P/M） titanium-based composites. The Ti composite with 4% （mole fraction） ZrO2 sintered at 1100 °C for 4 h shows an appropriate mechanical property with a relative density of 93.9%, a compressive strength of 1380 MPa （570 MPa higher than pure Ti） and good plasticity （an ultimate strain above 24%）.

Synthesis and Photocatalytic Activity of TiO_2/V_2O_5 Composite Catalyst Doped with Rare Earth Ions

TiO2/V2O5 catalyst doped with rare earth ions was prepared by sol-gel method. Titanium tetrapropoxide and vanadium pentoxide were used as precursor of the composite catalyst and rare earth ions were used as dopant. The crystal phases, crystalline sizes, microstructure, absorption spectra of doped composite catalyst were studied by XRD, EDS, FT-IR and UV-Vis. Photoactivity of the prepared catalyst under ultraviolet irradiation were evaluated by degradation of methyl orange （MO） in aqueous solution. It is shown that the prepared catalyst is composed of anatase and futile. The rare earth ions are highly dispersed in composite catalyst. All the doped catalysts appear higher photocatalytic activity than TiO2/V2O5 catalyst and catalyst doped with Ce^4＋ present the best activity to MO.

Preparation, Characterization and Photo-Catalytic Behavior of Y_2O_3/TiO_2 Composite Semiconductor Nanopowder

Y 2O 3/TiO 2 samples were prepared by sol-gel process and characterized by means of X-ray diffraction (XRD), laser Raman spectra (LRS), UV-visible diffuse reflectance spectra (DRS), specific surface area (BET), and transmission electron microscopy (TEM). The results show that the relative intensity of 101 peak of anatase and 002 peak of rutile, the mean crystal diameter and mean particle diameter of Y 2O 3/TiO 2 samples decrease while specific surface area increases owing to doping Y 2O 3. Y 2O 3/TiO 2 samples have a larger specific surface area and higher thermal stability. Owing to quantum size effect, the reflectance of Y 2O 3/TiO 2 samples is larger than that of pure TiO 2 in the range of 380～460 nm and the position of Raman peaks varies slightly. Being a model reaction, the photo-catalytic degradation of methylene blue (MB) with positive charge and methyl orange (MO) with negative charge was investigated in TiO 2 and Y 2O 3/TiO 2 nanopowder suspension irradiated by high-pressure mercury lamp. As a result, the addition of Y 2O 3 to TiO 2 is detrimental to photo-activity of TiO 2 for MB photo-degradation and photo-catalytic behavior is enhanced due to 5%, 10% Y 2O 3 deposited on TiO 2 for the photo-degradation of MO. And the relationship between photo-physical properties and photo-activity was discussed.

STRUCTURE AND PROPERTIES OF COMPOSITE POLYURETHANE HOLLOW FIBER MEMBRANES

Composite polyurethane(PU)-SiO_2 hollow fiber membranes were successfully prepared via optimizing thetechnique of dry-jet wet spinning,and their pressure-responsibilities were confirmed by the relationships of pure water flux-transmembrane pressure(PWF-TP)for the first time.The origin for this phenomenon was analyzed on the basis of membranestructure and material characteristics.The effects of SiO_2 content on the structure and properties of membrane wereinvestigated.The experimental results indicated that SiO_2 in membrane created a great many interfacial micro-voids andplayed an important role in pressure-responsibility,PWF and rejection of membrane:with the increase of SiO_2 content,theability of membrane recovery weakened,PWF increased,and rejection decreased slightly.

In-situ route for the graphitized carbon/TiO composite photocatalysts with enhanced removal efficiency to emerging phenolic pollutants

TiO2 is the most photoactive material because of its superstrong photooxidizing ability,and TiO2 photocatalysis has been widely applied in sustainable water treatment and environmental remediation.However,poor sunlight or visible-light harvesting efficiency and fast recombination rate of the photogenerated charge carriers severely limit the practical applications of TiO2.To overcome these problems,the present work demonstrates a facile in-situ co-condensation method combined with hydrothermal treatment to prepare a series of graphitized carbon/TiO2 composite photocatalysts,and anatase TiO2 phase andp-p-conjugated polycyclic aromatic carbon structure are created simultaneously.As-prepared TiO2/C composites exhibit remarkably high visible-light photocatalytic activity in the degradation of aqueous emerging phenolic pollutants,acetaminophen(APAP)and methylparaben(MPB),and apparent rate constant of the TiO2/C composite with carbon doping level of 10.3%for APAP and MPB removal is 7.6 and 2.8 times higher than that of bare TiO2,and 6.2 and 2.6 times higher than that of Degussa P25 TiO2.Based on the results of photoelectrochemical experiments,indirect chemical probe measurements,and ESR spectroscopy,it is verified that doping TiO2 with graphitized carbon is responsible for this enhanced photocatalytic activity,which renders the improved visible-light harvesting ability,the accelerated separation of the photogenerated charge carriers,and enlarged BET surface areas.Through analyzing the intermediates yielded in the photodegradation process,the pathway of visible-light photocatalytic degradation of APAP and MPB over the TiO2/C composite is proposed.

Impregnation of carbonaceous nanofibers into glassy polymer-based composite membrane for CO_2 separation

The development of defect-free composite membrane(CM) is often challenging due to poor dispersion and distribution of filler particles in the polymer matrix. Despite the attractive physicochemical properties and gas separation performance of carbon nanotube(CNT) based CM, CNT displayed poor dispersion characteristics in most polymer matrix domain. Instead of incorporating CNT, a viable alternative, carbon nanofiber(CNF) which exhibits similar properties as CNT, but improved dispersion quality in the polymer matrix is found. In this work,CNF particles were incorporated in poly(2,6-dimethyl-1,4-phenylene oxide)(PPOdm) polymer continuous phase for CM development. The optimum gas separation performance of the PPOdm-CNF CM(11.25 at 197.02 barrer of CO_2 permeability) was obtained at 3 wt% of CNF loading. Compared to pristine PPOdmmembrane,CO_2 permeability and CO_2/CH_4 selectivity of PPOdm-3 wt% CNF CM were enhanced by 180% and 55%, respectively.At 3 wt% CNF loading, the filler particles were dispersed and distributed more homogenously, in which no obvious CNF agglomeration was observed. In addition, the incorporation of CNF particles also enhanced the mechanical and thermal properties of the resultant CM.

Photocatalytical Inactivation of Enterococcus faecalis from Water Using Functional Materials Based on Natural Zeolite and Titanium Dioxide

The functional materials based on natural zeolite （clinoptilolite）, TiO2-zeolite and Ag-TiO2-zeolite have been successfully synthesized by solid-state reaction in fast-hydrothermal conditions. The obtained functional materials were investigated by X-ray diffraction （XRD）, FT-1R （Fourier transform infrared） spectroscopy, DRUV-VIS （diffuse reflectance ultraviolet-visible） spectroscopy, BET （Brunauer-Emmett-Teller） and SEM/EDX （scanning electron microscope/energy dispersive X-ray spectrometer） analyses. The XRD results indicated that the clinoptilolite structure has a good thermal stabilization after the fast-hydrothermal treatment. Also, the high specific surface area about 92.55 m^2.g^-1 was noticed for Ag-TiO2-zeolite functional material. The presence of dopants was evidenced from EDX spectra. The enhanced bactericidal activity of Ag-TiO2-zeolite catalyst is proved through damaging of Enterococcusfaecalis colonies under visible irradiation, at different material doses and irradiation times.

Preparation of narrow band gap V_2O_5/TiO_2 composite films by micro-arc oxidation

V2Os/TiO2 composite films were prepared on pure titanium substmtes via micro-arc oxidation （MAO） in electrolytes consisting of NaVO3. Their morphology and dements were characterized by scanning electron microscopy （SEM） and energy-dispersive X-ray （EDX） analysis. Phase composition and valence states of species in the films were characterized by X-ray diffraction （XRD） and X-ray photoelec- tron spectroscopy （XPS）. Ultraviolet-visible diffuse reflectance spectra （UV-Vis DRS） were also employed to evaluate the photophysical property of the films. The VEOs/TiO2 composite films show a sheet-like morphology. Not only V205 phase appears in the films when the NaVO3 concentration of the electrolyte is higher than 6,10 g/L and is loaded at the surface of anatase, but also V4＋ is incorporated into the crystal lattice of anatase. In comparison with pure TiO2 films the V2Os/TiO2 composite films exhibit significantly narrow band gap energy. The film prepared in an electrolyte consisting of NaVO3 with a concentration of 8.54 g/L exhibits the narrowest band gap energy, which is approximately 1.89 eV. The V2Os/TiO2 composite films also have the significantly enhanced visible light photocatalytic activity. The film prepared in an electrolyte consisting of NaVO3 with a concentration of 8.54 g/L exhibits the best photocatalytic activity and about 93% of rhodamine is degraded after 14 h visible light radiation.

Composite Electrodeposited PbO2/Co3O4 on a Ti Substrate as Positive Electrode Materials for a Hybrid Supercapacitor

PbO2/Co3O4 composites were prepared on a Ti substrate by means of a composite electrodeposition method in Pb2+ plating solution containing dissolved nano-Co3O4 particles. X-ray diffraction（XRD）, scanning electron microscopy（SEM）, energy dispersive spectrometry（EDS） and transmission electron microscopy（TEM） were used to characterize the chemical composition and morphology of the PbO2/Co3O4 composites. The electrochemical and capacitance performance of the composites were investigated by cyclic voltammetry（CV）, charge-discharge tests and electrochemical impedance（EIS）. The results indicate that the composites comprise rutile phase Co3O4 and β-PbO2. In addition, the surface of the composite electrode is rough and porous. The PbO2/Co3O4 composites exhibit a high specific capacitance up to 215 F/g, which is ten times higher than that of the pure-PbO2 and two times higher than that of the pure-Co3O4 in 1 mol/L NaOH electrolytes.

Thermal and Structural Analyses of PMMA/TiO₂Nanoparticles Composites

In the present work, composites of poly (methyl methacrylate)/titanium oxide nanoparticles (100/0, 97.5/2.5, 95/5, 92.5/7.5, 90/10 and 0/100 wt/wt%)were prepared to be used as bioequivalent materials according to their importance broad practical and medical applications. Thermal properties as well as X-ray diffraction analyses were employed to characterize the structure properties of such composite. The obtained results showed variations in the glass transition temperature (Tg), the melting temperature (Tm), shape and area of thermal peaks which were attributed to the different degrees of crystallinity and the existence of interactions between PMMA and TiO2 nanoparticle molecules. The XRD patterns showed sharpening of peaks at different concentrations of nano-TiO2 powder with PMMA. This indicated changes in the crystallinity/amorphosity ratio, and also suggested that the miscibility between the amorphous components of homo- polymers PMMA and nano-TiO2 powder is possible.The results showed that nano-TiO2 powder mix with PMMA can improve the thermal stability of the homo-polymer under investigation, lead- ing to interesting technological applications.

Development of High Efficient Composite Anodes

A new type of high efficient Ti composite anodes for electrodeposition of MnO 2 was successfully developed and was widely satisfied with production in many factories in China. The process parameters of electrolysis in using the composite anodes were optimized and discussed.

High-permeance crosslinked PTMSP thin-film composite membranes as supports for CO_2 selective layer formation

In the development of the composite gas separation membranes for post-combustion CO_2 capture, little attention is focused on the optimization of the membrane supports, which satisfy the conditions of this technology. The primary requirements to the membrane supports are concerned with their high CO_2 permeance. In this work, the membrane supports with desired characteristics were developed as high-permeance gas separation thin film composite(TFC) membranes with the thin defect-free layer from the crosslinked highly permeable polymer, poly[1-(trimethylsilyl)-1-propyne](PTMSP). This layer is insoluble in chloroform and can be used as a gutter layer for the further deposition of the CO_2-selective materials from the organic solvents. Crosslinking of PTMSP was performed using polyethyleneimine(PEI) and poly(ethyleneglycol) diglycidyl ether(PEGDGE) as crosslinking agents. Optimal concentrations of PEI in PTMSP and PEGDGE in methanol were selected in order to diminish the undesirable effect on the final membrane gas transport characteristics. The conditions of the kiss-coating technique for the deposition of the thin defect-free PTMSP-based layer, namely, composition of the casting solution and the speed of movement of the porous commercial microfiltration-grade support, were optimized. The procedure of post-treatment with alcohols and alcohol solutions was shown to be crucial for the improvement of gas permeance of the membranes with the crosslinked PTMSP layer having thickness ranging within 1-2.5 μm. The claimed membranes showed the following characteristics: CO_2 permeance is equal to 50—54 m^3(STP)/(m^2 h bar)(18,500—20,000 GPU), ideal CO_2/N_2 selectivity is 3.6-3.7, and their selective layers are insoluble in chloroform. Thus, the developed highpermeance TFC membranes are considered as a promising supports for further modification by enhanced CO_2 selective layer formation.

Synthesis and characterization of Fe_3O_4@SiO_2 magnetic composite nanoparticles by a one-pot process

Fe3O4@SiO2 core–shell composite nanoparticles were successfully prepared by a one-pot process. Tetraethyl-orthosilicate was used as a surfactant to synthesize Fe3O4@SiO2 core–shell structures from prepared Fe3O4 nanoparticles. The properties of the Fe3O4 and Fe3O4@SiO2 composite nanoparticles were studied by X-ray diffraction, transmission electron microscopy, energy dispersive spectroscopy, and Fourier transform infrared spectroscopy. The prepared Fe3O4 particles were approximately 12 nm in size, and the thickness of the SiO2 coating was approximately 4 nm. The magnetic properties were studied by vibrating sample magnetometry. The results show that the maximum saturation magnetization of the Fe3O4@SiO2 powder（34.85 A·m^2·kg^–1） was markedly lower than that of the Fe3O4 powder（79.55 A·m^2·kg^–1）, which demonstrates that Fe3O4 was successfully wrapped by SiO2. The Fe3O4@SiO2 composite nanoparticles have broad prospects in biomedical applications; thus, our next study will apply them in magnetic resonance imaging.

Fabrication of nickel oxide functionalized zeolite USY composite as a promising adsorbent for CO_(2) capture

Adsorption process is considered to be the most promising alternative for the CO_(2) capture to the traditional energy-intensive amine absorption process,and the development of feasible and efficient CO_(2) adsorbents is still a challenge.In this work,the NiO@USY(ultrastable Y)composites with different NiO loadings were prepared for the CO_(2) adsorption using Ni(NO_(3))_(2) as the precursor.The composites were characterized by X-ray photoelectron spectroscopy,X-ray diffraction,nitrogen adsorption–desorption test,scanning electron microscopy analysis,and thermogravimetric analysis,and were evaluated for the CO_(2) adsorption capacity,CO_(2)/N2 adsorption selectivity and CO_(2) cycle adsorption capacity.The characterization results show that after the activation at 423 K,the Ni(NO_(3))_(2) species were well dispersed into the surface of zeolite USY,and after the further activation at 823 K,Ni(NO_(3))_(2) could be converted into highly dispersed NiO.The adsorption results show that the presence of the active component NiO plays an important role in improving the CO_(2) adsorption performance,and the NiO@USY composite with a NiO loading of 1.5 mmol·g^(-1) USY support displays a high adsorption capacity and adsorption selectivity for CO_(2),and shows a good cycle stability.In addition,the Clausius–Clapeyron equation was used to evaluate the isosteric heat of adsorption of CO_(2) on the NiO(1.5)@USY composite,and the heat of adsorption was 17.39–38.34 kJ·mol^(-1).

Surface and interface analysis of HAP/TiO2 composite films on Ti6Al4V

The composite films constituted of hydroxyapatite (HAP) submicron particles embedded in the gel composed of the titania nanoparticles were prepared on commercial Ti6Al4V plates with titania buffer layer obtained by a spin-coating technique. The films were annealed in air at 450 ℃, 550 ℃ and 650 ℃, respectively. The phase formation, surface morphology, andinterfacial microstructure of the films were investigated by X-ray diffraction(XRD),Fourier transform infrared spectroscopy (FT-IR), field emission-scanning electron microscopy(FE-SEM) and energy dispersive X-ray (EDS) analysis. The results show that the as-prepared films are all well-crystallized, dense,homogeneous, and there was a close interfacial bond between the film and the substrate. The results of adhesion test indicate that there is a good bonding strength between the film and the substrate. The bone-like apatite formation on the surface of the films after immersion in acellular simulatedbody fluid(SBF) validated their bioactivities.