烟气SO2与氧化锌在水溶液中的反应研究

以氧化锌为吸收剂的烟气脱硫工艺能实现硫、锌资源的回收利用,特别适合于铅锌冶炼行业的烟气净化。试验研究了氧化锌与SO2在水溶液中的反应过程。通过固、液相中亚硫酸盐含量,锌离子浓度以及溶液pH值等对反应过程进行了表征,考察了SO2浓度、温度对反应的影响。试验结果表明,SO2在水溶液中首先是与氧化锌反应生成固体亚硫酸锌,然后固体亚硫酸锌溶解进入液相。当SO2水溶液w(SO2)1%以上时,25～35℃的反应温度对于提高SO2吸收率有利,进一步的表观反应活化能分析表明,氧化锌和SO2水溶液的反应活性与Ca(OH)2和SO2水溶液的反应活性相似。     

Effect of nickel impurities on zinc electrodeposition

The kinetics of nickel-zinc co-deposition and the effect of nickel on zinc morphology have been studied by means of chemical analysis, X-ray diffraction and SEM observations of cathodic deposits obtained in various experimental conditions, including acid and alkaline baths. It has been shown that nickel ions, even if present in the electrolyte at very low concentrations (1 ppm), do not deposit under mass transport controlled conditions but are dragged by zinc ions whose concentration influences the nickel current. With regard to zinc morphology, it has been observed that nickel reduces the grain size of the zinc crystals formed during the electrodeposition.     

Photo-reduction of hexavalent chromium in aqueous solution in the presence of zinc oxide as semiconductor catalyst

Common sources of chromium in wastewater are electroplating and leather industries. Hexavalent chromium is more toxic and carcinogenic compared to its trivalent counterpart. Conversion of Cr(VI) to Cr(III) in an aqueous medium by photocatalytic reduction using UV radiation and ZnO semiconductor catalyst has been investigated using potassium dichromate as the model compound. Effects of the process parameters such as ZnO loading (0–3 g/L) and intensity of UV radiation (0–125 W medium pressure Hg vapour lamp) on photocatalytic reduction were investigated. Initial concentration of substrate solution was varied from 40 to 120 mg/L. A comparison of the performance of the ZnO photocatalyst achieved in this study with that reported in the literature for photocatalytic and conventional processes is presented. The initial rate of the photochemical method was found to be independent of the concentration of potassium dichromate. Methanol was added as a hole scavenger for enhancement of the photo-reduction. Initial rate of photo-reduction was found to be independent of the concentration of methanol above a particular value. A probable mechanism and the corresponding kinetic model have been proposed for the photo-reduction and tested by experimental results. An alternative rate equation based on the LHHW model compares well with the mechanistic rate equation.     

铁锈对环氧乙烷水溶液失控反应的影响

采用绝热量热仪对环氧乙烷(EO)水溶液?铁锈/Fe2O3体系进行了绝热量热实验,得到了铁锈、Fe2O3固体与EO水溶液接触时的起始放热温度、最高放热温度和压力、绝热温升、失控反应过程温度、压力等参数. 结果表明,在实验条件下EO水溶液与现场铁锈接触时失控反应特征不明显,未出现温度、压力剧升现象;发生失控反应的起始放热温度、最高反应温度、最高压力等随EO浓度降低而减小,达到最大反应速率的时间在30 min内,30wt% EO水溶液?Fe2O3体系的起始放热温度接近100℃,纯EO?Fe2O3体系的起始放热温度为150℃. Fe2O3固体比现场铁锈对EO及其水溶液失控反应的催化诱导作用更明显,且随EO浓度升高,失控后果更严重.     

Effect of temperature and pH values on aggregation behavior of polymeric surfactants in aqueous solution

A novel kind of polymeric surfactant based on carboxymethyl cellulose and poly(ethylene oxide) dodecyl ether acrylate (CMC‐AR₁₂EO₉) was synthesized through ultrasonic irradiation. Aggregation behavior in aqueous solution at different temperatures and pH values was investigated by dynamic laser scattering and fluorescence probe. The results show that, with the increase of temperature, polymeric surfactants are favorable to form multimolecular micelles with narrower polydispersity of size distribution. At a higher temperature, the multimolecular micelles tend to aggregate bigger sized particles that are unstable and would be disaggregated at higher shear rate. At the elevated pH values, the size of micelles reduces drastically because of strong damage of alkali to aggregates, whereas nonpolar and insoluble domains formed by the hydrophobic blocks of polymeric surfactants are insensitive to pH changes. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 945–949, 2005     

Effect of substrate surface treatment on the hydrothermal synthesis of zinc oxide nanostructures

In this investigation, ZnO nanostructures were coated via hydrothermal process on glass substrate surfaces, which were treated by acidic and alkaline solutions. Furthermore, the ZnO structure was doped by different amounts of Al⁺³ ions to investigate the microstructural variation. Characteristics of the samples by XRD and SEM analyses confirmed the formation of different morphologies and various crystal sizes for the nanostructured ZnO on the substrates including nanoflower, nanorod, and nanopanel morphologies. Furthermore, XRD results showed that the Zn²⁺ concentration was a crucial factor in changing the grain size. EDS analysis confirmed the uniform distribution of Al dopant, while the FTIR spectra revealed the presence of Al–O and Zn–O stretching bonds in the coatings. The results confirmed that the sample, which was etched by fused NaOH had a uniform and compacted structure. Moreover, it was evident the proposed treatment and synthesis process was successful in the formation of uniform nanostructured ZnO film on the glass substrate without the requirement for seed layer deposition.     

柠檬酸钠含量和pH对锌合金表面镀镍的影响

采用柠檬酸钠作为镍配位剂,在ZAT10锌合金表面电沉积镍,利用扫描电镜、阴极极化等方法分析了镀层表面形貌和孔隙状况,研究了柠檬酸钠含量和镀液pH对镀镍层形貌的影响.结果表明,在柠檬酸钠含量为70～180g/L、镀液pH为4.7～7.0的条件下,所得镀镍层平整致密,无条纹、孔隙和裂纹产生.     

杂质对MDEA-TETA溶液吸收与解吸CO2性能的影响

本文实验研究了MDEA-TETA溶液中可能存在的杂质对其吸收与解吸CO2性能的影响,这些杂质包括固体颗粒FeS、SiO2、活性炭;无机盐FeSO4、NaCl、CaCl2、MgCl2;有机物甲醇、三甲胺、三乙醇胺、二甲基乙醇胺等.研究结果表明:FeSO4、三甲胺、三乙醇胺可促进MDEA-TETA溶液对CO2的吸收;其它杂...     

Fabrication and characterization of zinc oxide nanoparticle coated magnetic iron oxide: Effect of S-layers adsorption on surface of oxide

Mixed zinc oxide nanoparticle coated magnetic iron oxide has been prepared by a sol–gel and co-precipitation routes. Magnetic iron oxide nanoparticles were synthesized by co-precipitation of ferric and ferrous ions with ammonia, and then zinc oxide was coated onto the surface of magnetic iron oxide by hydrolysis of zinc precursors. As a result, zinc oxide coated magnetic iron oxide nanoparticles with an average size of 68 nm were obtained. The crystalline bacterial cell surface layer)S-layer (used in this study was isolated from Lactobacillus helveticus ATCC 12046. The S-layer was adsorbed onto the surface of zinc oxide nanoparticle coated magnetic iron oxide. The nanoparticles were analyzed by X-ray powder diffractometry (XRD), infrared spectroscopy (FTIR), transmission electron microscopy (TEM), and field emission scanning electron microscopy (FESEM) were used to characterize the structural and the chemical features of the nanocomposites. The infrared spectra indicate that the S-layer-nanoparticle interaction occurs. This novel nanoparticle showed admirable potential in adsorption of S-layers on the surface of oxides for drug delivery.     

纳米氧化锌的分散与表面改性研究

研究了纳米氧化锌在水体系中的分散及其分散后的表面改性处理。分别以聚乙二醇(PEG20000)和钛酸酯偶联剂(NDZ)为分散剂和表面改性剂,通过正交实验研究了分散剂、表面改性剂的用量以及球磨速度和研磨时间对分散稳定性和改性效果的影响。结果表明,最佳工艺条件为:1)分散过程中w(PEG20000)=0.5%,球磨速度为2 000 r/min、球磨时间为1 h;2)表面改性过程中w(NDZ)=1%、球磨时间为1 h、球磨速度为1 000 r/min。采用激光粒度测试仪及SEM对产物粒度及形貌进行了表征,改性后氧化锌颗粒以较小的粒径存在,分散性有明显的提高。     

Effect of incorporation of surface treated zinc oxide on non-isocyanate polyurethane based nano-composite coatings

Non-isocyanate polyurethanes (NIPUs) based on cyclic carbonate-amine chemistry are an emerging area for polymer synthesis and is being extensively studied for various applications. A successful utilization of this technology can eliminate many of the issues associated with conventional polyurethane chemistry. While these polymers have not yet achieved commercial significance, research is being devoted to methods for synthesizing polymers or oligomers containing cyclic carbonate groups as well as studying their applications in thermoplastic and thermosetting systems.     

溶液初始pH值对2,4-D臭氧直接反应动力学的影响

引言 目前,农药被大量研制及施用,由此带来的农药污染越来越受到人们的重视.含氯苯氧梭酸类除草剂2,4-D(2,4-二氯苯氧乙酸)是一种使用较广、应用较早的除草剂.2,4-D自然降解较慢,由于具有非挥发性和可溶性,易导致地下水或地表水污染,水体中已经可以检测到2,4-D的存在.     

Removal of malachite green from aqueous solution by zinc oxide nanoparticle loaded on activated carbon: Kinetics and isotherm study

In this research, a novel adsorbent, zinc oxide nanoparticle loaded on activated carbon (ZnO-NP-AC) was synthesized by a simple, low cost and efficient procedure. Subsequently, this novel material was characterizated and identified by different techniques such as Brunauer, Emmett and Teller (BET), scanning electron microscopy (SEM), X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FT-IR) analysis. Unique properties such as high surface area (>603 m²/g) and low pore size (<61 Å) and average particle size lower than 100 Å in addition to high reactive atom and presence of various functional groups make it possible for efficient removal of malachite green (MG). In batch experimental set-up, optimum conditions for quantitative removal of MG by ZnO-NP-AC was attained following searching effect of variables such as adsorbent dosage, initial dye concentration and pH. Optimum values were set as pH of 7.0, 0.015 g of ZnO-NP-AC at removal time of 15 min. Kinetic studies at various adsorbent dosage and initial MG concentration show that maximum MG removal was achieved within 15 min of the start of every experiment at most conditions. The adsorption of MG follows the pseudo-second-order rate equation in addition to interparticle diffusion model (with removal more than 95%) at all conditions. Equilibrium data fitted well with the Langmuir model at all amount of adsorbent, while maximum adsorption capacity was 322.58 mg g⁻¹ for 0.005 g of ZnO-NP-AC.     

Thermodynamical and catalytic aspects of zinc separation from aqueous solution

The present research work examines extraction mechanism of zinc by D2EHPA (Di-2-ethyl hexyl phosphoric acid) and comprehensively studies the main effective parameters on the process. Results of thermodynamic experiments showed that zinc extraction by D2EHPA was endothermic and spontaneous, and thermodynamic parameters including entropy and enthalpy were+27.37 J·mol^-1·K^-1 and 25.21 kJ·mol^-1, respectively. Gibbs free energy was varied between -7.21 kJ·mol^-1 and -8.41 kJ·mol^-1 with the variation of temperature from 20℃ to 70℃. Solution ionic strength was increased by addition of potassium and lithium sulfate solution while addition of calcium sulfate decreased ionic strength whereby zinc extraction efficiency was also decreased. TBP showed positive synergism at concentration of 5% (v/v) and negative synergism effect at concentrations of 2% and 10%. Simultaneous addition of both TBP and salt caused extraction efficiency to drop significantly and lower both TBP and ionic strength efficiency. Results showed that a continuous addition of TBP tends to effectively improve the zinc extraction efficiency. Experiments in the presence of catalyst Ni-Raney demonstrated that zinc extraction kinetic increases remarkably and due to easy recycling of the catalyst, we can propose a novel idea in solvent extraction field.     

Investigation of PEG adsorption on the surface of zinc oxide nanoparticles

The influence of polyethylene glycol (PEG) on the adsorption at zinc oxide/polymer solution interface has been determined. PEG macromolecules bond with the solid surface mainly via the -OH group of the surface of ZnO nanoparticles, which may interact with PEG through hydrogen bonding. Adsorption isotherms demonstrate the marked influence of the PEG molecular weight and the concentration of polymer solution on the extent of adsorption. The thickness of the adsorbed polymer layer on ZnO nanoparticles was calculated on the basis of measurements of their suspension viscosities in the absence and presence of adsorbed polymer. Results show that the thickness of the adsorption layer increased with increasing polymer molecular weight and the concentration of polymer solution. The main factors responsible for the changes in zeta potential were determined on the basis of the data obtained. The shift of the slippage plane away from the surface of ZnO nanoparticles plays major role below pH_iep. Above pH_iep, the blockage of the adsorption sites is the predominant factor.     

Preparation of zinc oxide nanocrystals with high stability in the aqueous phase

ZnO nanocrystals (NCs), potential candidates for photoluminescent applications, have attracted increasing attention recently because of their good biocompatibility, low cost, and convenient synthesis. However, their stability and fluorescent quenching, particularly in the aqueous phase, still hampers their use in biological applications. We report herein the synthesis of ZnO NCs modified by amphiphilic methoxy poly(ethylene glycol)‐grafted poly(styrene‐alt‐maleic anhydride) (SMA‐g‐MPEG) copolymer based on the sol–gel method. We demonstrated a simple solution to address those challenges. Compared with unmodified ZnO NCs, SMA‐g‐MPEG modified ZnO NCs exhibited a significantly improvement in the stability and photoluminescent properties in the aqueous phase over current unmodified ones. This simple synthesis provides a novel platform for the preparation of ZnO NCs for biological applications. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Adsorption of cadmium and zinc from aqueous solution on natural and activated bentonite

The adsorption of cadmium and zinc ions on natural bentonite heat-treated at 110°C or at 200°C and on bentonite acid-treated with H₂SO₄ (concentrations: 0·5 mol dm^?3 and 2·5 mol dm^?3), from aqueous solution at 30°C has been studied. The adsorption isotherms corresponding to cadmium and zinc may be classified respectively as H and L types of the Giles classification which suggests the samples have respectively a high and a medium affinity for cadmium and zinc ions. The experimental data points have been fitted to the Langmuir equation in order to calcualte the adsorption capacities (X_m) and the apparent equilibrium constants (K_a) of the samples; X_m and K_a values range respectively for 4·11 mg g^?1 and 1·90 dm³ g^?1 for the sample acid-treated with 2·5 mol dm^?3 H₂SO₄ [(B)-A(2·5)] up to 16·50 mg g^?1 and 30·67 dm³ g^?1 for the natural sample heat-treated at 200°C [B-N-200], for the adsorption process of cadmium, and from 2·39 mg g^?1 and 0·07 dm³ g^?1, also for B-A(2·5), up to 4·54 mg g^?1 and 0·45 dm³ g^?1 [B-N-200], for the adsorption process of zinc. X_m and K_a values for the heat-treated natural samples were higher than those corresponding to the acid-treated ones. The removal efficiency (R) has also been calculated for every sample; R values ranging respectively from 65·9% and 8·2% [B-A(2·5)] up to 100% and 19·9% [B-N-200], for adsorption of cadmium and zinc.     

钾盐镀锌溶液中铁杂质的影响及消除

详细介绍了钾盐镀锌溶液中铁杂质对镀锌的有害影响。分析了铁杂质的来源并提出了几种去除铁杂质的方法。     

Effect of surface-modified zinc oxide nanowires on solution crystallization kinetics of poly(3-hexylthiophene)

Interfacial interactions between donor and acceptor molecules are determinative to the device performance of hybrid photovoltaics. However, the dynamic process of such interactions remains largely obscure. In this work, we report the kinetic behavior of solution crystallization of poly(3-hexylthiophene) (P3HT) in anisole in the presence of ZnO nanowires by means of ultraviolet-visible absorption spectroscopy. ZnO nanowires are surface-modified by covalently attaching aliphatic and aromatic ligands to enhance the miscibility and interfacial interactions between P3HT and ZnO nanowires. Upon cooling the hot solution to room temperature, a significant time-dependent chromism occurs spontaneously. Analysis of the kinetics of isothermal solution crystallization across a range of crystallization temperature displays that the growth rate of the crystals scales with polymer concentration as R ∝ C^1.6 for both the control P3HT and P3HT with ZnO nanowires. The Lauritzen–Hoffman theory of secondary nucleation is utilized to analyze the kinetic behavior of crystallization, and the fold surface free energies of the crystals of P3HT in anisole are calculated to be 6.6–10.3 × 10⁻² J m⁻². It is found that the addition of surface-modified ZnO nanowires decreases the fold surface free energy by 21.5% and 43.8%, respectively, for aliphatic and aromatic ligands.     

温度和pH对溶液中硼富集程度的影响

温度和pH影响溶液中硼（以B₂O₃计）的富集程度,通过实验测定计算得到不同温度时硼饱和溶液中B₂O₃的质量分数随pH的变化,并通过方程拟合出不同pH条件下硼饱和溶液中B₂O₃质量分数随温度的变化。实验结果表明：在10~50 ℃条件下硼饱和溶液中硼的总浓度随pH的增加呈现先减小后增大的趋势,60~80 ℃条件下硼饱和溶液中硼的总浓度随pH的增加呈现先减小后增大再减小的趋势;在pH 为8~11条件下随着pH的增加溶液中硼的总浓度增加,当pH=12时硼饱和浓度先增大后减小。