微波合成PtRu/CNTs催化剂及其电催化性能

为了获得有良好电催化活性的碳负载铂钌合金的催化剂，提出一种快速均匀的微波辐射加热的多元醇方法.用氯铂酸和氯化钌的乙二醇溶液为前驱体，碳纳米管（CNTs）为载体，采用该方法合成了PtRu/CNTs电催化剂.利用透射电镜(TEM)、X-射线衍射(XRD)和能量散射X 射线能谱（EDX）对催化剂进行了表征,并用循环伏安实验评价了催化剂对甲醇电化学氧化的电催化活性．结果表明，PtRu合金纳米粒子具有均匀的粒径，在2.0~4.0 nm之间，平均粒径为3.4 nm，并高度分散在CNTs表面．PtRu/CNTs电催化剂对甲醇的电化学氧化具有良好的电催化活性.     

Synthesis of modified D401 chelating resin and its adsorption properties for Pb^2＋

A novel chelating resin with sulfonic group was synthesized by chemical modification of D401 resin with sulphonation reaction and characterized by FT-IR spectrometry. The adsorption properties of the novel chelating resin for Pb²⁺ were studied by batch adsorption, and the adsorption process was analyzed from thermodynamics and kinetics aspects. The adsorption mechanism of Pb²⁺ on the modified D401 chelating resin was discussed by FT-IR spectrometry. Experimental results show that in the Pb²⁺ concentration range of 200–400 mg/L, the adsorption capacities of the modified D401 chelating resin for Pb²⁺ increase by 77%–129%, and Langmuir isothermal adsorption model is more suitable for the equilibrium adsorption data. Adsorption is an endothermic process that runs spontaneously. Kinetic analysis shows that the adsorption rate is mainly governed by liquid film diffusion. The best pH value under adsorption condition is 4–5. The saturated resin can be regenerated by 3 mol/L nitric acid, and the adsorption capacity remains stable after five consecutive adsorption-desorption cycles. The maximal static saturated adsorption capacity of the resin is 206 mg/g at 333 K in the Pb²⁺ concentration range of 200–400 mg/L. The modified D401 chelating resin is an efficient adsorbent for the removal of Pb²⁺ from its single-metal ion solution. Foundation item: Project(708049) supported by the Important Item Cultivation Foundation of Scientific Innovation Project of Colleges and Universities of China     

Effects of different conditions on Pb2+ adsorption from soil by irrigation of sewage in South China

Pb²⁺ adsorption onto a soil by irrigation of sewage in the Pearl River Delta of South China was examined as a function of the reaction time, solution pH, initial lead concentration, organic matter (humic acid) and competitive ions (Cu²⁺). The adsorption of Pb²⁺ onto the soil was investigated on batch equilibrium adsorption experiments. Results show that the Pb²⁺ adsorption on the soil is relatively rapid in the first 30 min and reaches equilibrium at 2 h, and the kinetics of the adsorption process on the soil is well characterized by the pseudo-second order reaction rate. Langmuir, Freundlich and Temkin isothermal models are fit for the adsorption of Pb²⁺ onto the soil, and the maximum amount of Pb²⁺ adsorption (Q _m) is 7.47 mg/g. The amount of Pb²⁺ adsorption increases with increasing the pH at the range of 1.2–4.5 and reaches a plateau at the range of 4.5–12. The presence of humic acid in soil decreases the adsorption of Pb²⁺ onto the soil at solution pH of 8 since the negatively charged humic acid with Pb²⁺ is difficult to be adsorbed on the negatively charged soil surface. The adsorption of Pb²⁺ onto the soil also decreases in the presence of Cu²⁺ due to the competition adsorption between Pb²⁺ and Cu²⁺.     

用于Pb2+、Hg2+离子选择性固相萃取的微流控芯片

为实现微流控芯片对重金属Pb~(2+)、Hg~(2+)离子的选择性固相萃取,首先采用3-氯丙基三甲氧基硅烷和5-甲基苯并三氮唑对纳米二氧化硅进行硅烷偶联改性,随后以改性纳米二氧化硅为基础,设计并制备了可更换吸附剂的一体化填充式固相萃取芯片.测试结果表明:改性后不仅吸附剂的团聚现象得到明显改善,且当pH=5时,对Pb~(2+)的吸附率可达99.1%,对Hg~(2+)的吸附率可达98.9%,而对Cr~(3+)的吸附率为20.4%,对Mn~(2+)的吸附率仅为13.2%.即使样品中混有干扰离子(K~+、Na~+或Mn~(2+))时,对Pb~(2+)、Hg~(2+)离子的吸附率仍均可达97%以上.当进样流速≤1.5 mL/min时,微流控芯片对Pb~(2+)或Hg~(2+)的吸附率可达98%以上;以0.5 mol/L的盐酸和2%的硫代尿素为洗脱液,控制流速在0.20.3 mL/min范围内时,芯片对Pb~(2+)或Hg~(2+)的洗脱率均达到92%以上.用于Pb~(2+)、Hg~(2+)离子的选择性固相萃取芯片的成功制备,有助于微流控技术在重金属污染监测领域的应用和推广.     

Preparation of Functionalized Graphene Nano-platelets and Use for Adsorption of Pb<Superscript>2+</Superscript> from Solution

Functionalized graphene nano-platelets (FGN) were obtained via treating graphene nanoplatelets (GN) with HNO₃, and served as adsorbent for the removal of Pb²⁺ from solutions. We investigated the FGN adsorption capacity for Pb²⁺ at different initial concentrations, varying pH, contact time and temperature. The characterization results of scanning electron microscopy (SEM), thermal analysis (TG/DTG), Fourier transform infrared spectroscopy (FT-IR) and Brunauer-Emmett-Teller (BET) method indicated that FGN layers were thin and possess large specific area with oxygen-containing functional groups grafted onto their surface. Meanwhile, the determined equilibrium adsorption capacity of FGN for Pb²⁺ was 57.765 mg/g and adsorption isotherms well confirmed to Langmuir isotherms models. The results reveals that the FGN has better effect of water treatment.     

Effect of Pb substitution on the microstructure and ferroelectric properties of Ba<Subscript>0.7</Subscript>Sr<Subscript>0.3</Subscript>TiO<Subscript>3</Subscript> ceramic

Ferroelectric Ba0.7Sr0.3TiO3（BST） and partially Pb^2＋ substituted for Ba^2＋ ceramics （Ba0.7-xPbx）Sr0.3TiO3 （x=0.1-0.4, BPST） were prepared by using conventional solid-reaction method. XRD analysis shows that the samples microstructure changes from cubic phase to tetragonal one with the Pb^2＋ content increasing. ESEM analysis shows that the Pb^2＋ substituted samples have a denser and more uniform surface morphology than that of pure BST. Measured electrical properties suggest that the Pb^2＋ substitution for Ba^2＋ in the BST system enhances the ferroelectric performance obviously when x=0.2. In addition, the substitution increases the samples Curie temperature （To） r （Ba0.5Pb0.2）Sr0.3TiO3 ceramic has good ferroelectric properties measured at a maximal electric field of 30 kV/cm under the condition of room temperature. The corresponding saturated polarization （Ps）, remnant polarization （Pr） and coercive field （Ec） is respectively 15.687 μC/cm^2, 8.100 μ C/cm^2 and 6.611 kV/cm. The measured Tc of （Ba0.5Pb0.2）Sr0.3TiO3 is 117 ℃.     

PtRu/C和PtNi/C催化剂合成及其对甲醇氧化的电催化性能

采用微波多元醇法合成PtRu/C和PtNi/C催化剂,利用透射电镜（TEM）和X-射线衍射仪（XRD）对催化剂的微观结构和形貌进行了表征.结果表明,在催化剂中PtRu和PtNi合金纳米粒子的平均粒径分别为2.7和3.0 nm,粒径均匀,并高度均匀地分散在碳载体上.电化学测试结果表明,与Pt/C催化剂相比,PtRu/C和PtNi/C催化剂对甲醇的电化学氧化具有更低的起始电位和更稳定的极化电流,说明PtRu/C和PtNi/C催化剂对甲醇氧化具有更稳定的电催化性能和更好的抗CO中毒性能.这是由于合金催化剂中的Ru和Ni可以在较低的电位下与其表面吸附水形成含氧物种,使Pt表面吸附的CO等中间物氧化为CO2,避免了催化剂的CO中毒.     

Adsorption of Pb^2＋ on macroporous weak acid adsorbent resin from aqueous solutions： Batch and column studies

The adsorption properties of a novel macroporous weak acid resin (D152) for Pb²⁺ were investigated with chemical methods. The optimal adsorption condition of D152 resin for Pb²⁺ is at pH 6.00 in HAc-NaAc medium. The statically saturated adsorption capacity is 527 mg/g at 298 K. Pb²⁺ adsorbed on D152 resin can be eluted with 0.05 mol/L HCl quantitatively. The adsorption rate constants determined under various temperatures are k _{288 K}=2.22×10⁻⁵ s^t-1, k _{298 K}=2.51×10⁻⁵ s⁻¹, and k _{308 K}= 2.95×10⁻⁵ s⁻¹, respectively. The apparent activation energy, E _a is 10.5 kJ/mol, and the adsorption parameters of thermodynamics are ΔH ^Θ=13.3 kJ/mol, ΔS ^Θ=119 J/(mol·K), and ΔG ^Θ 298 K =−22.2 kJ/mol, respectively. The adsorption behavior of D152 resin for Pb²⁺ follows Langmuir model. Foundation item: Project(2008F70059) supported by the Scientific and Technological Research Planning of Zhejiang Province, China     

The Catalysis of NAD^＋ on Methanol Anode Oxidation Electrode for Direct Methanol Fuel Cell

A tentative idea of developing a liquid-catalytic system on methanol anode oxidation was proposed by analyzing the characteristics of methanol anode oxidation in direct methanol fuel cell. The kinetics of methanol oxidation at a glassy carbon electrode in the presence of nicotinamide adenine dinucleotide ( NAD^ ) was investigated. It is found that the current density of methanol oxidation increases greatly and the electrochemical reaction impedance reduces obviously in the presence of NAD^ compared with those in the adsenee of NAD^ . The catalytic activity of NAD^ is sensitive to temperature. When the temperature preponderates over 45℃, NAD^ is out of fuuction of catalysis for methanol oxidation, which is probably due to the denaturation of NAD^ at a relatively high temperature.     

Characterization and application of tourmaline and beryl from Brazilian pegmatite in adsorption process with divalent metals

In this study, the original tourmaline and beryl mineral samples have been collected from a Brazilian pegmatite. The objective of this study was to examine the adsorption behavior of Brazilian ciclosilicate samples, towards divalent metals (Pb²⁺, Mn²⁺, and Zn²⁺) in ethanol solution has been studies by a batch technique. The ciclosilicate samples were characterized by elemental analysis, Fourier transform infrared spectroscopy, helium picnometry, mercury porosity, and nitrogen adsorption–desorption. The Langmuir expression for adsorption isotherm was applied in order to determine the adsorption capacity to form a monolayer and the constant related to the adsorption intensity. In aqueous solution there was a significant adsorption increase with the temperature and pronounced synergistic effects were observed. The maximum number of moles adsorbed was determined to be 12.48 and 11.49 mmol/g for systems Pb²⁺/beryl and Pb²⁺/tourmaline, respectively. The energetic effects caused by metal cations adsorption were determined through calorimetric titrations. Thermodynamics indicated the existence of favorable conditions for such Pb²⁺-, Mn²⁺-, and Zn²⁺–OH interactions.     

甲醇电化学氧化催化剂的失活机理研究

采用电化学老化试验研究了PtRu催化剂的活性衰减过程.结果表明,老化试验后,电催化剂的粒径有所增加,这在一定程度上减小了催化剂的表面积,降低了催化活性.更为严重的是,催化层中活性组分的流失改变了催化剂的组成,使催化剂对甲醇氧化反应的催化活性大幅降低.这是导致PtRu催化剂失活的重要原因.     

Ce掺杂对Mn/ACN催化剂低温NH3-SCR脱硝活性的影响

采用浸渍法将活性组分Mn、Ce负载到酸处理后的椰壳活性炭(ACN)上,制备出采用浸渍法将活性组分Mn、Ce负载到酸处理后的椰壳活性炭(ACN)上,制备出Mn/CAN和Mn-Ce/ACN脱硝催化剂,在固定床上对所制备的催化剂进行了脱硝性能评价,着重探讨了两种活性组分的负载顺序、负载量对催化剂活性的影响,并对催化剂进行了BET、SEM、XRD、XPS表征。结果表明,通过比较Mn/CAN和Mn-Ce/ACN催化剂的脱硝活性,发现Ce的添加能明显提高催化剂的脱硝活性,在温度高于90oC时能达到90%以上的NO去除率,在120-250oC之间,NO转化率维持在100%。活性组分的负载顺序及负载量是影响催化剂活性的重要因素。同时负载活性组分,Ce、Mn负载量均为5%时,催化剂表现出最好的脱硝性能。Mn负载在活性炭上,降低了活性炭的比表面积和孔容,而Mn、Ce负载量均为5%的Mn-Ce/ACN的比表面积和微孔孔容降到695.0m2/g和0.130cm3/g,随着Mn、Ce负载量的增加,比表面积和孔容进一步降低;当Ce、Mn负载量均增加到10%时,其比表面积和微孔孔容只有539.8m2/g和0.106 cm3/g。Mn3+和Mn4+共存于两种催化剂上,而Ce4+ 和Ce3+共存并使Mn-Ce/CAN上Mn4+比例略微增加,导致催化剂表现出最好的脱硝性能.     

Removal of Pb^2＋ and Cd^2＋ by adsorption on clay-solidified grouting curtain for waste landfills

Pb^2＋ and Cd^2＋ in leachate were adsorbed on clay-solidified grouting curtain for waste landfills with equilibrium experiment. The cation exchange capacity was determined with ammonium acetate. And the concentration of heavy metal cations in leachate was determined with atomic absorption spectrophotometer. Their equilibrium isotherms were measured, and the experimental isotherm data were analyzed by using Freundlich and Langmuir models. The results show that the adsorption capacities of the heavy metal cations are closely related to the compositions of clay-solidified grouting curtain, and the maximum adsorption appears at the ratio of cement to clay of 2 ： 4 in the experimental conditions. At their maximum adsorption and pH 5.0, the adsorption capacities of Pb^2＋ and Cd^2＋ are 16.19 mg/g and 1.21 mg/g. The competitive adsorption coefficients indicate that the adsorption of clay-solidified grouting curtain for Pb^2＋ is stronger than that for Cd^2＋. The adsorption process conforms to Freundlich＇s model with related coefficient higher than 0. 996.     

Fluorescence detection for H<Subscript>2</Subscript>PO<Subscript>4</Subscript><Superscript>-</Superscript> based on carbon dots/Fe<Superscript>3+</Superscript> composite

A novel fluorescent probe for H₂PO₄ ^- was designed and fabricated based on the carbon dots/Fe³⁺ composite. The carbon dots were synthesized by an established one-pot hydrothermal method and characterized by transmission electron microscope, X-ray diffractometer, UV-Vis absorption spectrometer and fluorescence spectrophotometer. The carbon dots/Fe³⁺ composite was obtained by aqueous mixing of carbon dots and FeCl₃, and its fluorescence property was characterized by fluorescence spectrophotometer. The fluorescence of carbon dots was quenched by aqueous Fe³⁺ cations, resulting in the low fluorescence intensity of the carbon dots/Fe³⁺ composite. On the other hand, H₂PO₄ ^- reduced the concentration of Fe³⁺ by chemical reaction and enhanced the fluorescence of the carbon dots/Fe³⁺ composite. The Stern-Volmer equation was introduced to describe the relation between the relative fluorescence intensity of the carbon dots/Fe³⁺ composite and the concentration of H₂PO₄ ^-, and a fine linearity (R ²=0.997) was found in the range of H₂PO₄ ^- concentration of 0.4-12 mM.     

Influence of rare earth co-dopant on the photocatalytic property of TiO<Subscript>2</Subscript> nano-particles

A series of nanometer TiO2 photocatalysts co-doped respectively with rare earth Er3+-Ce3+ and La3+-Fe3+ were prepared by sol-gel method,and the photocatalytic activity under ultra-violet light was evaluated by photocatalytic degradation of methyl blue.The crystallographic forms,particles size,and morphology were characterized by XRD and TEM.The results showed that the optimum heat temperature of co-doped TiO2 was 550 ℃,and the co-doped TiO2 kept anatase.The anatase crystal had the average size of 20 nm.The ...     

Synthesis and characteristics of a novel heavy metal ions chelator

Polyacrylamide-urea-sulfanilamide(PUS) was prepared as a novel heavy metal ions chelator and successfully used to simultaneously remove heavy metals from wastewater effluents.The effects of reaction parameters(sodium hydroxide,material ratio,temprature and contact time) were monitored to specify the best synthesis conditions.PUS was chemically characterized by means of infrared spectroscopy(FTIR) and ultraviolet-visible(UV-Vis).The simultaneous chelation performance of PUS towards selected heavy metals ions,Ni2+,Cu2+,Pb2+,Zn2+,Cd2+ was discussed,showing that Ni2+,Cu2+,Pb2+,Zn2+ could be better chelated.It is indicated that the synthesized PUS is a potential remediation material when used for the treatment of wastewater containing metal ions.     

Electrocatalytic activity of tungsten trioxide microspheres, tungsten carbide microspheres and multi-walled carbon nanotube-tungsten carbide composites

Tungsten trioxide micropheres were prepared by spray pyrolysis, and tungsten carbide microspheres were produced by spray pyrolysis-low temperature reduction and carbonization technology. Multi-walled carbon nanotube-tungsten carbide composites were prepared by the continuous reduction and carbonization process using multi-walled carbon nanotubes (MWCNTs) and WO₃ precursor by molecular level mixing and calcination. The morphology and structure of the samples were characterized by scanning electron microscope and transmission electron microscope. Furthermore, the crystal phase was identified by X-ray diffraction. The electrocatalytic activity of the sample was analyzed by means of methanol oxidation. Tungsten carbide microspheres were catalytic active for methanol oxidation reaction. Nevertheless tungsten trioxide microspheres and multi-walled carbon nanotube-tungsten carbide composites were not catalytic active for methanol oxidation reaction. These results indicate that tungsten carbide micropheres are promising catalyst for methanol oxidation.     

Mechanism and behaviors of Cr3+-doped TiO2

TiO₂ powder and TiO₂ thin film on the surface of glazed ceramic tile were prepared by sol-gel method. The influences of different doping Cr³⁺ concentration on the photocatalytic activity of TiO₂ were discussed, UV-visible and X-ray diffraction analysis were used to test the performance of TiO₂ powder and film. The results indicate that photocatalytic activity of doping Cr³⁺-TiO₂ thin film is higher than that of powder, and the interaction between Cr³⁺-doped and substrate can greatly enhance the photocatalytic activity. The results of X-ray diffraction and photoabsorption show that the Cr³⁺-doped energy level in TiO₂ is 0.62 eV high from the top of valence band, which belongs to the type of deep energy level doping. On the basis of the semiconductor energy level theory and Cr³⁺ dopant energy level, the semiconductor energy level model of Cr³⁺ in TiO₂ powder and thin film were established, and the doping mechanisms of Cr³⁺-doped in TiO₂ powder and thin film were analyzed. Foundation item: Project (20466001) supported by the National Natural Science Foundation of China     

Modification of Fe<Subscript>3</Subscript>O<Subscript>4</Subscript> magnetic nanoparticles by L-dopa or dopamine as an enzyme support

Fe3O4 magnetic nanoparticles were prepared by co-precipitation of Fe^2＋ and Fe^3＋ in an ammonia solution, and its size was about 36 nm measured by an atomic force microscope. Fe3O4 magnetic nanoparticles were modified by L-dopa or dopamine using sonication method. The analysis of FTIR clearly indicated the formation of Fe-O-C bond. Direct immobilization of trypsin （EC： 3.4.21.4） on Fe3O4 magnetic nanoparticles with L-dopa and dopamine spacer was investigated using glutaraldehyde as a coupling agent. No significant changes in the size and magnetic property of the three kinds of magnetic nanoparticles linked with or without trypsin were observed. The existence of the spacer molecule on magnetic nanoparticles could greatly improve the activity and the storage stability of bound trypsin through increasing the flexibility of enzyme and changing the microenvironment on nanoparticles surface compared to the naked magnetic nanoparticles.     

Structures and properties of La<Subscript>0.8</Subscript>Sr<Subscript>0.2</Subscript>MnO<Subscript>3+σ</Subscript>-z SBA-15 (z=0, 1, 2, 4) perovskite catalysts

Mesoporous La_0.8Sr_0.2MnO_3+σ/z SBA-15 (z = 1, 2, 4) perovskite oxides were synthesized via hard-templating with ordered mesoporous silica SBA-15 as the template. The as-prepared samples were characterized by XRD, SEM, AFM, BET, and XPS and the catalytic activity was tested for CO oxidation. The wide-angle XRD patterns showed that La_0.8Sr_0.2MnO_3+σ perovskite was formed. The SEM and AFM analyses exhibited that La_0.8Sr_0.2MnO_3+σ by hard-templating method had much smaller particle size (18 nm) than that (40 nm) by the sol-gel method. The perovskite-type oxides La_0.8Sr_0.2MnO_3+σ/z SBA-15 (z = 1, 2, 4) also displayed a higher BET surface area from 70 to 143.7 m²/g and a disordered mesostructure from nitrogen sorption analysis, as well as a small-angle XRD pattern. Moreover, the La_0.8Sr_0.2MnO_3+σ/z SBA-15 (z = 1, 2, 4) perovskite exhibited a much higher activity in CO oxidation than the conventional La_0.8Sr_0.2MnO_3+σ perovskite. Further analysis by the means of XPS techniques indicated that the existence of high content of O_ads/O_latt species contributed to the high activity.