Silica sol/Nano-Au/PVP修饰金电极电致化学发光测定槐定碱

基于槐定碱对联吡啶钌（Ru（bpy）3^2＋）在电致化学发光中的增敏机理,通过传感器修饰技术,将Silica sol/Nano-Au/PVP修饰到金电极表面,建立了简单、快捷测定槐定碱的新方法。实验表明,最佳实验条件下,在1.6×10^-7-1.6×10^-4mol/L范围内,槐定碱的浓度与其对应的电化学发光强度值呈良好的线性关系,I=4.000×10^7c＋262.2,r^2=0.994 5,检出限（S/N=3）为3.5×10^-9mol/L。连续平行测定浓度为1.6×10^-5mol/L的槐定碱溶液6次,其相对标准偏差（RSD）为2.9%。该方法具有较高的选择性和灵敏度,样品处理简单快速,用于槐定碱的测定,结果满意。

Effect of SiO_2 concentration in silica sol on interface reaction during titanium alloy investment casting

Using silica sol as a binder for titanium investment casting is very attractive due to its good stability and reasonable cost as compared with yttrium sol and zirconium sol. However, the mechanism of interface reaction in the related system remains unclear. In this investigation, the interface reaction between Y_2O_3-SiO_2(YSi) shell mold and titanium alloys was studied. A group of shell molds were prepared by using Y_2O_3 sand and silica sol with different contents of SiO_2. Ti-6Al-4V alloy was cast under vacuum by gravity casting through cold crucible induction melting(CCIM) method. Scanning electron microscopy(SEM) and energy dispersive x-ray spectroscopy(EDS) were employed to characterize the micromorphology and composition of the reaction area, respectively X-ray photoelectron spectroscopy(XPS) was used to confirm the valence state of relevant elements. White ligh interferometer(WLI) was used to obtain the surface topography of Y-Si shells. The results show that the thickness of reaction layers is below 3 μm when the SiO_2 content of silica sol is below 20 wt.%. Whereas, when the SiO_2 content increases to 25 wt.%, the thickness of the reaction layer increases sharply to about 15 μm. There is a good balance between chemical inertness and mechanical performance when the SiO_2 content is between 15 and 20 wt.%. Moreover, it was found that the distribution of SiO_2 and the roughness at the surface of the shell are the key factors that determine the level of reaction.

固定Ionic liquid/Silica sol/Nafion膜中的联吡啶钌电化学发光行为的研究及应用

制备了Ionic liquid/Silica sol/Nafion-联吡啶钌复合物膜修饰金电极。采用循环伏安(CV)和电致化学发光(ECL)法,考察了联吡啶钌和左氧氟沙星在此修饰电极上的电化学及其发光行为。结果表明,此修饰电极表现出很好的电化学活性和电化学发光响应。基于左氧氟沙星对固定化联吡啶钌在0.1 mol/L磷酸盐缓冲液中的弱电化学发光信号有较强的增敏作用,建立了电化学发光检测盐酸左氧氟沙星的新方法。在最佳实验条件下,左氧氟沙星浓度在1.0×10-7～1.0×10-4mol/L范围内与相对发光强度呈线性关系(r2=0.998 4),检出限(S/N=3)为1.59×10-9mol/L。连续平行测定2.2×10-5mol/L的左氧氟沙星溶液10次,发光强度的相对标准偏差(RSD)为3.6%。对样品进行回收率试验,回收率在95.6%～103.5%之间,RSD(n=5)为3.0%。该方法具有较高的选择性和灵敏度,样品处理简单快速,用于盐酸左氧氟沙星的测定,结果满意。

Preparation and Characterization of Hybrid Aqueous Dispersions Composed of Silica Sol and Poly(styrene-co-acrylate)

A stable silica sol with 3-5 nm in diameter, which can form homogeneous film without crack, was prepared and characterized. Then, the inorganic-organic hybrid aqueous dispersion composed of such a silica sol and an emulsion of styrene （St） and acrylate （Ac） copolymer was prepared and the hybrid effect between the silica sol and poly（St-co-Ac） was observed by Fourier transform infra-red （FT-IR） spectroscope. The toughness of the film prepared by this kind of hybrid aqueous dispersion was excellent, as it was enhanced appreciably by commixing with a small amount of poly（St-co-Ac） emulsion. Some amino-polysiloxane modified hybrid aqueous dispersions were also prepared and the properties of the modified dispersions and their films were investigated. The experimental results showed that the film prepared with such an amino-polysiloxane modified hybrid dispersion exhibited excellent hydrophobicity and low surface energy after heat treatment for 1.5 h, during which the formation of the graft copolymer was observed. The surface energy of this film decreases as a result of the enrichment of siloxane segments on the film surface.

Research on New Silica Sol Matrix Used in Fluid Catalytic Cracking Reaction

A new silica sol binder was obtained by mixing the acid-modified aluminium sulfate and water glass. The effect of SiO2 concentration in sodium silicate, pH value and polymerization was investigated. The new silica sol binder, which possessed abundant pore volume and suitable acid amount, was an ideal component for preparing cracking catalyst. As a result, the corresponding catalyst comprising the new binder showed excellent performance. Compared with the reference sample, the liquefied petroleum gas(LPG) and propylene yield obtained over this catalyst increased by 3.49 and 1.20 percentage points, respectively. The perfect pore structure and suitable Lewis acid amount of new silica sol were the possible reason leading to its outstanding performance.

Application of Vacuum Drying to Silica Sol Ceramic Mold

Silica sol ceramic mold was made at room temperature with JN-30 silica sol, silica powder and NH4Cl. It is found that the harden time of silica sol ceramic mold is only 0.5 to 1.5 h under the amount of NH4Cl solution of 7% to 8% with 15% concentration, and less surface cracks occur by using vacuum drying. The proper vacuum drying process parameters： vacuum drying temperature is 80 to 100℃, drying time is 5 h and vacuum is 0.06 to 0.07MPa. The harden mechanics, vacuum drying mechanics and the reason of less surface cracks of silica sol ceramic mold by vacuum drying： were also analyzed in this paper.

Experiment on the silica sol imbibition of low-permeability rock mass:With silica sol particle sizes and rock permeability considered

It’s a universal engineering problem to seal micro-cracks of low-permeability argillaceous rock mass by grouting in the fields of civil engineering and mining.This paper achieved the grouting sealing of lowpermeability artificial rocks with the permeability of 0.1–40 mD by adopting silica sol imbibition grouting.The variation characteristics of particle size,viscosity,and contact angle of silica sol during solidification and the pore size distribution of low-permeability artificial rocks were measured,and spontaneous imbibition tests of the artificial rocks were carried out.Finally,combined with the imbibition theory,percolation theory,and fracture medium grouting principle,the silica sol imbibition mechanism of lowpermeability rocks and soil was discussed.The results show that:(1)Silica sol can be injected into artificial rocks with the minimum permeability of 0.1 mD through spontaneous imbibition;(2)The particle size increase of silica sol leads to decreased wettability,affinity,and injectability in grouting materials;and(3)In the range of 0.1–40 mD,the grout absorption first increases and then decreases with increased permeability.The number of large pores and fractures in the rock mass is related to injectability,and the number of small and medium pores is related to the internal driving force of imbibition.This study provides a theoretical basis for silica sol grouting sealing of low-permeability argillaceous rocks and is,therefore,an important reference for application.

Nano-Au/Silica sol/PVP修饰金电极上电化学发光测定盐酸硫必利

采用溶胶-凝胶法制备了Nano—Au／Silicasol／PVP修饰金电极，并基于盐酸硫必利对联吡啶钌（Ru（bpy）2/3＋）在该修饰电极上弱电化学发光具有较强的增敏作用，建立了电化学发光检测盐酸硫必利的新方法。在最佳实验条件下，盐酸硫必利浓度在1．0×10-7～1．0×0-4mol／L范围内与相对发光强度呈线性关系（r2=0．9978），检出限（S／N-3）为6．7×10-10mol／L。连续平行测定1．0×10-5mol／L盐酸硫必利溶液10次，发光强度的相对标准偏差（RSD）为1．789／6。对样品进行回收率试验，其回收率在97．7％～103．9％之间，RSD为2．62％。该方法具有较高的选择性和灵敏度，样品处理简单快速，用于盐酸硫必利的测定，结果满意。

Facile and Controlled Synthesis of Silica Sol Nanospheres Through a Modifi ed Sol-Gel Process

An effective and reproducible preparation of silica sol nanospheres via a modified sol-gel process has been described. Monodisperse and stable silica sol nanospheres with uniformsize were successfully obtained through the optimized synthesis in which the mixture of tetraethyl orthosilicate （TEOS） and ethanol was followed by the addition of water and ammonium hydroxide （NH3） separately, and the size of silica sol spheres was strictly controlled in the range of 25-119 nm with a narrow size distribution by fine adjustment of several reaction parameters. Results showed that in the presence of low concentration of TEOS, spheres size rose first and reached maximum when H2O concentration was up to 66 g/L. However, the diameter of silica sol spheres decreased above 66 g/L of H2O concentration. Furthermore, it was also found that the size and size distribution of silica sol nanospheres were affected by NH3 concentration. As NH3 concentration increased from 15 to 35 g/L, the diameter declined from 83 to 64 nm. Nevertheless, higher NH3 concentration would result in relatively broad size distribution, and gelation occurred when NH3 concentration reached 44 g/L. In addition, the effect of the different feed rates ofNH3 on the size growth of silica sol nanospheres was also discussed.

Preparation of Magnesia Insulation Materials by Walnut Shell Powder Impregnated with Silica Sol

In order to reduce the thermal energy loss of high temperature kilns and furnaces and lower the surface temperature of the kiln body,magnesia insulation materials were prepared using self-made magnesia porous aggregates(using high purity magnesia powder as starting material and potassium oleate as the foaming agent),middle grade magnesia powder,calcium aluminate cement,and SiO_(2) micropowder as starting materials,introducing walnut shell powder impregnated with silica sol(short for Sws)as a pore-forming agent.The effects of the Sws addition(0,10%,15%,and 20%,by mass)and the sintering temperature(1300,1350,1400,and 1480℃)on the properties of magnesia insulation materials were studied.The results show that(1)for the specimens fired at 1480℃,when the Sws addition is 10%,the cold compressive strength is 22 MPa;when the Sws addition is 20%,the thermal conductivity is 0.368 W·m^(-1)·K^(-1)(350℃);(2)nano-silica in the silica sol reacts with MgO in the matrix to form forsterite,which encapsulates the pores volatilized from the walnut shell powder and forms closed pores.

The preparation of high concentration alkaline silica sol with the method of vacuum distillation

High concentration alkaline silica sol has been prepared by the method of vacuum distillation, which shows that the stable and high concentration silica sol can be obtained under conditions as follows： 70℃, vacuum degree of 0.095Mpa and dispersant of SDS. The experimental results show that the sol particles size decreases with mass concentration first and then increase, sol viscosity increases with mass concentration during the concentrating process. The TEM method was used to study the dispersion behavior of sol particles, its result showed that sol particles dispersed more uniformly after concentrating process than before concentrating distinctly. It could be concluded that the disperse degree of alkaline silica sol could be increased by addition of right dispersant. The dispersion mechanism of dispersant in alkaline silica sol was also discussed.

Formation of macroporous gel morphology by phase separation in the silica sol-gel system containing nonionic surfactant

The phase separation and gel formation behavior in an alkoxy-derived silica sol-gel system containing C16EO15 has been investigated. Various gel morphologies similar to other sol-gel systems containing organic additives were obtained by changing the preparation conditions. Micrometer-range interconnected porous gels were obtained by freezing transitional structures of phase separation in the sol-gel process. The dependence of the resulting gel morphology on several important reaction parameters such as the starting composition, reaction temperature and acid catalyst concentration was studied in detail. The experimental results indicate that the gel morphology is mainly determined by the time relation between the onset of phase separation and gel formation.

Effects of Silica Sol on Structure and Properties of Core-Shell Silicon-Acrylic Materials

Silica sol prepared by sol-gel method was introduced into poly (butyl acrylate) (PBA)/poly (butyl acrylate-styrene-methacryloxypropyl trimethoxysilane) (PSBM) core-shell emulsions to prepare a series of paper surface sizing agents. The rheological measurement indicated that PSBM emulsions exhibited shear-thinning behavior, and the phenomena became more pronounced with increasing silica sol concentration. Dynamic mechanical analysis (DMA) demonstrated that the stronger interfacial interaction between silica sol and polymer matrix, but microphase separation took place with excess silica sol. Thereby the tensile strength and thermal stability of emulsion films were increased with desirable silica sol concentration, and when silica sol concentration was greater than 6 wt%, the tensile strength leveled off and the decomposition temperature decreased from 351.19℃ to 331.63℃. The degree of crystallinity increased from 5.12% to 10.98% with 4% silica sol addition, resulting in enhanced rigidity of films. Furthermore, the interaction between polymer and fiber was improved with certain amount of silica sol, resulting in improved sizing degree, ring crush strength, surface strength and folding strength. However, excessive crosslinking will be harmful for the properties of sized paper.

STUDIES ON SYNTHESIS OF SILICA SOL-ORGANIC POLYMER COMPOSITE EMULSION

An emulsion of polystyrene/poly (butylacrylate-methyl methacrylate acrylic acid) core/shell latex particles (PS/P (BA-MMA-AA)) has been prepared by use of three synthetic methods. The effects of synthetic methods on the distribution of carboxyl groups in latex particles were studied. The results show that the seed emulsion polymerization in which the pre-emulsified monomers were added by dropping method to the second stage is the best technique for obtaining the optimum distribution of carboxyl groups on the surface of the latex particles. Furthermore, by using PS/P (BA-MMA-AA), a type of novel composite emulsion of silica sol-PS/P (BA-MMA-AA) was synthesized with the above method. By observation through transmission EM, the morphology of the latex particles obtained shows that a composite structure has been formed between silica sol particles and organic polymer particles.

APPLICATION OF BORON MODIFIED SILICA SOL ON RETENTION AND DRAINAGE

In this paper it was studied that these dosage effects of CPAM, cationic starch?boron modified silica sol(BMS), Al2(SO4)3, pH value and electrolyte on the retention and drainage of different microparticulate systems including CPAM, cationic starch and boron silica sol. The research results indicated that CPAM had no good retention when used with boron silica sol. The best retention efficiency was the microparticulate system of CPAM + cationic starch with boron modified silica sol; Secondly was that of cationic starch with boron modified silica sol; The worst was that of CPAM with boron modified silica sol. The retention efficiency had no relation with the addition order between CPAM and cationic starch. It was also found that the microparticulate retention system of boron modified silica sol could be used in alum-rosin sizing and in acidity, neutral or alkaline papermaking conditions. This system also could be used with close circulate water so that it could reduce the water pollution and waste.

Effect of Variant Counterions on Stability and Particle Size of Silica Sol

The effects of variant counterions with ionic strength of 0.05, 0.10, 0.20 and 0.25 mol·kg^-1 on the stability and particle size of silica sols have been studied using the traditional methods of Ubbelohde viscosity measurement, TEM and titration respectively, finding that the stability and particle size of the silica sols are all concerned with the acidic, positively electric properties and the sizes of the counterions, as well as the attraction between the counterions and surface silicon hydroxyl groups of the silica sols. The small positively charged counterions lead to the decrease in particle sizes, making the silica sol the most stable. But the larger weakly acidic counterions can restrict the particle sizes of the silica sols and easily make the sols coagulate. It was also found that there existed a linear relationship between log r and log η, which has not ever been reported. The effect of temperature on the stability and particle sizes was also discussed.

Electrocrystallizations of copper on glassy carbon in CuCl_2 silica sol and aqueous solutions

Electrocrystallizations of copper from both CuCl_2 silica sol and aqueous solutions were studied by the chronoamperometry technique.It was found that current density contributions of the double-layer charging（iDL） in current-time transients（CTTs） from both of the solutions were large.An adsorption-nucleation based model was proposed to analyze quantitatively the CTTs,by which copper electrocrystallization mechanism was characterized as progressive nucleation with 3D growth（3DP） under diffusion control.The diffusion coefficient of copper ions and the AN_∞products in aqueous solutions were larger than that in silica sols, which indicated that copper nucleation was inhibited in sol solution.The large iDL may be resulted from the adsorption of chloride ions on the electrode surface.

Silica sol/Nano-Au/PVA/L-cysteine修饰金电极电致化学发光测定甲氧氯普胺的研究

在甲氧氯普胺对联吡啶钌具有较好电化学发光增敏效果的基础上,制备出Silica sol/Nano-Au/PVA/L-cysteine修饰金电极,并通过电致化学发光法,考察了联吡啶钌及联吡啶钌-甲氧氯普胺体系在此电极上的电化学及电化学发光行为。该修饰电极对联吡啶钌-甲氧氯普胺体系有良好的电致化学发光响应特性;在最优条件下,在1.0×10-7～1.0×10-4mol/L范围内甲氧氯普胺浓度与其对应的电化学发光强度值线性关系良好,检出限（S/N=3）为1.40×10-9mol/L;通过平行测定1.0×10-5mol/L甲氧氯普胺溶液8次,发光强度值相对偏差（RSD）为1.8%,样品回收率在98.3%～104.4%之间,RSD为2.3%（n=5）。

Combination of Silica Sol and Potassium Silicate via Isothermal Heat Conduction Microcalorimetry

Isothermal heat conduction microcalorimetry was utilized as a novel characterization method to investigate the polymerization processes of silica with both thermodynamic and kinetic parameters when the combination of silica sol and potassium silicate was stirred at temperatures of 25.0, 35.0, and 45.0 ℃. The silica polymerization was characterized by the greater enthalpy change at each higher temperature and by the reaction orders of the silica sol and potassium silicate, which varied rapidly, instantaneously, and constantly from low to high all the time, up and down in an alternate manner. When the reaction order of the silica sol and potassium silicate was 3.0, the maximum rate constant occurred at 25.0℃ （k= 1.22 × 10 ^-4 mol-2·dm6·s-1）. The two temperature regions （25.0-35.0 ℃ region with a faster rate and 35.0-45.0℃ region with a lower rate） reflected a two-stage oligomerization of silica monomers with different oligomers formed in a two-step anionic mechanism. The measurements of particle size and pH value showed that the colloidal particles in the mixed silica sol and potassium silicate first dissolved, then ＂active＂ silica in the potassium silicate redeposited to make a distinct particle size distribution （Z-average size, 33.0-14.9 nm at 25.0 ℃） influenced both by pH value （9.82--11.97 at 25.0 ℃） and the mass fraction （53, 65, 75, and 85 mass/%） of the silica sol in the mixture. The processes of combination of the silica sol and potassium silicate did not result from acid-base neutralization reactions but from a complex polymerization of the ＂active＂ silica components which relate to silica monomers oligomerization with heat evolved （the total enthalpy changes, 1.6234-3.3882 J）.

Isolation, identification and primary application of bacteria from putrid alkaline silica sol

The putrefaction of alkaline silica sol was investigated in this paper. The total colony numbers in three alkaline silica sol samples were 1.47 ×^ 105, 1.25× 10^4, and 9.45 × 10^4 cfu. mL 1, respectively. The salt- and alkalitolerant strains were isolated and selected using nutrient agar medium at 2.5% salinity and pH 9.5. Basic morphological, physiological and biochemical tests were conducted to confirm the preliminary characterizations of the strains. Based on API 50 CH test and 16S rDNA gene sequence analysis, the isolated strains were finally identified as Exiguobacterium aurantiacum, Cyclobacteriaceae bacterium, Microbacterium sp., Acinetobacter sp., Stenotrophomonas maltophilia and Bacillus thuringiensis. The survivability of the strains under different conditions such as salinities, acidities and temperatures was also studied. Some suitable methods for degerming, such as product pipe steam sterilization and regular canister cleaning, were proposed. To explore the possibility of isolates in industrial application, their alkaline protease and amylase production abilities were preliminarily studied. Five strains produced alkaline protease, whereas two strains produced alkaline amylase. Thus, understanding of the putrefaction on alkaline silica sol would be beneficial for improving industrial production.