Preparation of barium sulfate particles using filtration dispersion precipitation method in O/W system

In this paper, a new method to synthesize BaSO₄ nano-particles in O/W system with filtration dispersion technology was developed. The nano-particles of barium sulfate were prepared using a type of filtration dispersion device with a plate porous disc as a dispersion medium. Working systems of barium chloride aqueous solution/30% TBP (in kerosene) with sulfuric acid were applied. The influence of the reactant concentration and the operation conditions were investigated. The morphology of the particles was observed by SEM, and the particle-size distributions were measured. The nano-particles prepared in O/W system were compared with those prepared by dispersing aqueous barium chloride solution into aqueous sodium sulfate solution with the same filtration dispersion device. The results showed that mono-dispersed BaSO₄ particles can be prepared using the filtration dispersion method in O/W systems. The surfaces of all the particles were smooth. The mean diameter of the particles was in the 100-400 nm range and decreased with the increase of flux of the two phases. The ratio of the two phases greatly affects the morphology of particles because of the excess concentration of [SO₄²⁻]. The particle size was also much smaller when the mixed two feeds were aqueous solutions.     

Mixed‐matrix membranes based on polyurethane containing nanohydroxyapatite and its potential applications

In this study, new asymmetric polyurethane (PU) mixed‐matrix membranes with different nanohydroxyapatite loadings were prepared via a dry–wet phase inversion method by the dispersion of hydroxyapatite (HA) nanoparticles in the PU matrix. The HA nanopowder was obtained by a wet chemical precipitation method; it showed an average crystallite size of 58.3 nm, a specific surface area of 261 m²/g, and a pore size of about 1.6 nm. The effects of the HA loading (10–50 wt %) on the PU membrane characteristics were studied. The scanning electron microscopy images revealed that the HA nanoparticles were well dispersed enough in the PU matrix. The average pore size in the top layer and porosity of the membranes slowly decreased, whereas the hydrophilicity and water permeability increased with increasing content of HA. The evaluation of the nanofiltration performance was performed by investigation of the NaCl rejection. The composite membranes had a higher salt‐removal capacity than the unfilled PU membrane. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41813.     

由铵盐制备高纯氟化钡的工艺研究

以氟化铵和氯化钡为原料,采用沉淀法制备了氟化钡。反应温度为25 ℃,反应时间为60 min,氯化钡初始质量分数为10%,氟化铵与氯化钡物质的量比为2.2,m(洗水)∶m(滤饼)=10∶1,可制备出纯度达99%以上的氟化钡。XRD谱图表明,样品氟化钡的所有衍射峰均与标准立方相氟化钡吻合,属立方晶系。该工艺流程简单,经济效益好。     

Preparation of barium hafnate fine powders by oxalate method

Barium hafnate (BaHfO₃) precursor was prepared by mixed barium nitrate and hafnium (IV) chloride with ammonium oxalate aqueous solution. Barium hafnate powders were obtained by decomposition of the precipitate precursor at 800 °C for 2 h. As a dispersant, polyethylene glycol (PEG6000) was used in the precipitation reaction and the influence of dispersant dosage on particle size was studied. X-ray diffraction analysis (XRD) showed the powders was pure cubic BaHfO₃ without impurities. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) demonstrated that the size distribution was uniform, and the average grain size was about 50 nm.     

膜分散微结构反应器制备纳米氧化锌的实验及模型

以硫酸锌和氢氧化钠为原料,在膜分散微结构反应器中通过快速均匀混合制备得到颗粒平均尺寸为10～20 nm的氧化锌,并利用混合尺度模型模拟了微反应器内纳米颗粒的成核、生长和团聚过程。模拟计算结果表明,在最初的0.6 ms内颗粒成核占主导地位,在1.6 ms以后以生长为主,同时由于颗粒数密度较大,颗粒运动碰撞造成团聚效应,使得颗粒尺寸具有一定的分布。混合尺度和反应物浓度对颗粒直径和分布有很大影响。模拟结果表明当混合尺度从50 μm减少到5 μm,纳米氧化锌颗粒从19 nm降低到12 nm。微反应器制备实验结果表明,随着膜孔径的减小,混合强度增加,纳米氧化锌颗粒平均直径从20 nm 降低至11 nm,当初始反应物浓度从0.05 mol·L^-1提高到0.20 mol·L^-1,氧化锌纳米颗粒尺寸由10 nm增大至16 nm。颗粒平均直径及分布的模拟值与实验值相符较好。     

反应沉淀法制备超细硫酸钡的研究

以精制硫化钡溶液和硫酸钠溶液为原料，在调速泵内采用液－液相反沉淀法合成超细颗粒硫酸钡液体，其条件为：硫化钡溶液质量浓度为15％，硫酸钠溶液质量浓度为26％，加入DTPA螯合剂，化合泵转速为2500r/min，得到平均粒径小于100nm的超细硫酸钡产品。     

Synthesis and photochromic property of nanoparticles with spiropyran moieties via one-step miniemulsion polymerization

Summary  Photochromic nanoparticles with spiropyran moieties were prepared by a facile one-step miniemulsion polymerization. The nanoparticle dispersion was obtained by mixing the monomers, spiropyran-containing molecules and hydrophobe, dispersing them into an aqueous solution with surfactant, subjecting the dispersion to ultrasonification and polymerizing the monomers by using a water soluble initiator. The shape and size of the nanoparticles was determined with the atomic force microscope (AFM) and dynamic light scattering (DLS), and the determined average diameter of the nanoparticles ranges from 30 nm to 60 nm. The absorption and fluorescence spectra for the nanoparticles dispersions reveal that the spiropyran molecules were successfully incorporated in the polymer nanoparticles. Moreover, the nanoparticle dispersions were found to exhibit enhanced photo-reversibility, photo-stability and relatively fast photo-responsive property compare to the same species in aqueous solution.     

硫酸钡表面的改性处理

采用湿法反应改性的方法，在硫酸钡的沉淀反应阶段在其表面嵌入硬脂酸长碳链分子，使硫酸钡表面由亲水性变成亲油性，从而使硫酸钡在聚乙烯醇溶液中的分散性得到改善，将其作为PP的填料可以使PP力学性能得到提高。     

柱状碳酸钡粒子的制备研究

以氢氧化钡和尿素为原料,采用均相沉淀法制备了碳酸钡粉体,通过添加合适的晶形控制剂,合成了柱状碳酸钡粒子.研究了合成条件及控制剂用量对碳酸钡粒子的影响及柱状碳酸钡的形成机理.并通过SEM和XRD进行了表征,制备了结晶完整、分散性良好的碳酸钡粒子.     

BaTiO3超细粉体的溶胶-沉淀法制备及其表征

采用溶胶-沉淀工艺制备BaTiO3纳米粉体,探讨了沉淀剂NaOH溶液浓度对制备BaTiO3粉体相组成的影响,提出了溶胶-沉淀法合成纯相BaTiO3的反应机理,并对沉淀水洗后的湿凝胶进行表面改性.探讨了添加表面活性剂及有机溶剂脱水过程对粉体团聚程度的有效控制.     

Colloidal processing of low-concentrated zirconia nanosuspension using osmotic consolidation

Colloidal processing was applied to a water-based suspension with 5 vol% zirconia nanoparticles of 10–15 nm in size. The nanosuspension was concentrated by evaporation or by a newly developed method of osmotic dehydration. The viscosity and stability of concentrated nanosuspensions were investigated. Osmotic consolidation of both nanosuspensions, concentrated by evaporation and osmotically dehydrated, was performed in a solution of polyethylene oxide separated from the nanosuspensions using a permeable membrane. Osmotic pressure generated a water flow from the nanosuspension to the polymer solution, concentrating the nanosuspension and eventually consolidating the nanoparticle network. The pore size distribution in dried nanoparticle compacts and pore size evolution during sintering were evaluated and discussed. The nanozirconia compacts were densified by pressure-less sintering to a relative density of up to 99.7% while maintaining the nanocrystalline structure.     

膜分散微反应器沉淀法制备高孔容SiO2材料

引言高孔容二氧化硅具有良好的光学性能,是高档涂料消光剂的首选[1-2],其消光效率随着孔体积的增大而提高。这是因为较高孔隙率的颗粒较轻,单位质量颗粒数较多,而颗粒对光的折射是产生消光所需的微粗糙度的主要原因[3]。     

四氯化硅液相鼓泡法制备纳米白炭黑工艺研究

以多晶硅副产物四氯化硅为原料,氨水为中和剂,十二烷基苯磺酸钠为改性剂,在水-醇-氨体系中利用液相鼓泡法制备纳米白炭黑,并采用IR、XRD、SEM、TEM对纳米白炭黑晶体结构、形貌、分散性及粒径进行表征。研究了醇水比、氨水用量、分散剂种类及用量、双氧水加入量等因素对纳米白炭黑分散性及粒径的影响。纳米白炭黑最佳制备工艺条件：体系总体积为70 mL,V（水）∶V（醇）∶V（氨）=38∶15∶12,六偏磷酸钠加入量为1.5%（质量分数）,双氧水用量为5 mL。IR、XRD表征结果表明产品为无定形二氧化硅;SEM、TEM表征结果表明纳米白炭黑粒径约100 nm且分散较好。     

一种钛酸钡制备方法实验研究

以硫酸法钛白生产过程中的中间产品工业钛液（TiOSO4）为钛源,通过常温水解获得正钛酸,经草酸溶解获得草酸氧钛酸,再与氯化钡共沉淀得到草酸氧钛酸钡,高温煅烧后制备得到电子级钛酸钡产品。实验确定最佳制备条件：钛液水解pH为2.5～3.5,草酸氧钛酸生成温度和草酸氧钛酸钡共沉淀温度均选择50～70 ℃,共沉淀pH为2.5,煅烧温度为800 ℃,煅烧时间为2 h。分析结果表明,以工业钛液为钛源生产钛酸钡的成本明显低于偏钛酸。     

Preparation of chitosan nanoparticles and their application to Antheraea pernyi silk

In this study, a chitosan nanoparticle dispersion solution as a novel multifunctional agent was developed to modify Antheraea pernyi silk. An ionization gelation methodology with chitosan and sodium tripolyphosphate (STPP) was used to prepare the chitosan nanoparticle solution, and then, Fourier transform infrared spectra, laser particle size analysis, and transmission electron microscopy (TEM) were used to characterize the structure and size distribution of the chitosan nanoparticles. The peaks at 3390.7, 1633.7, 1538.2, and 1258.1 cm⁻¹ revealed the reaction between the chitosan and STPP molecules in the chitosan nanoparticles. The average size of the nanoparticles in the aqueous dispersion solution was approximately 20 nm. TEM images clearly showed the round spherical morphology and the distribution of the particles in the solid state. The obtained chitosan nanoparticle dispersion solution was then applied to treat silk filaments and fabric. The results indicate that the surface of the chitosan‐nanoparticle‐treated A. pernyi silk fiber was rougher than that of the chitosan‐treated and untreated ones, and a higher specific surface was achieved. In addition, the antibacterial activity, breaking strength, and wrinkle‐resistance properties of the chitosan‐nanoparticle‐treated A. pernyi silk fabric were also enhanced. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

水基稳定分散的靶向药物用纳米Fe3O4的制备

用于靶向抗癌药物微球的磁性Fe3O4颗粒必须具有合适的粒径,并且保证其不发生团聚。采用化学共沉淀法制备了纳米Fe3O4磁性颗粒,XRD分析证实了产物的主要组成为立方晶系Fe3O4;粒度分析表明,产物平均粒径16.3 nm左右,粒径分布宽度约5.8 nm;采用高分辨透射电镜(HRTEM)观察产物形貌,证明纳米Fe3O4胶体溶液中磁性粒子呈球形分布,且未发生明显的团聚现象;测得Fe3O4胶体溶液ζ电位为+39.9 mV,颗粒吸附溶液中的C l-离子形成了吸附双电层结构,较强的静电排斥力阻止纳米粒子团聚,因此,制得的纳米Fe3O4胶体溶液具有很强的分散稳定性。     

工业氯化钡质量的快速测定

介绍利用硫酸银标准溶液滴定氯化钡溶液的快速测定工业氯化钡含量的新方法。     

Preparation and characterization of nanocomposite heterogeneous cation exchange membranes modified by silver nanoparticles

We prepared polyvinylchloride based nanocomposite heterogeneous cation exchange membranes by solution casting technique using cation exchange resin powder as functional groups agent and tetrahydrofuran as solvent. Silver nanoparticles were also used as fillers in membrane fabrication. The effect of silver nanoparticles concentration in casting solution on membrane physico/chemical and antibacterial characteristics was studied. The SEM images showed compact structure for the modified membranes. X-ray diffraction results also revealed that membrane crystallinity was clearly changed by increase of nanoparticle concentration. Membrane selectivity and transport number were enhanced initially by increase in nanoparticle content up to 4%wt in prepared membrane, and then showed decreasing trend by more increase in additive concentration from 4 to 8%wt. Selectivity and transport number were enhanced another time by further increase in nanoparticle loading ratio from 8 to 16%wt. Opposite trend was found for the membranes’ average grain size by variation in additive content. Ionic flux was also clearly enhanced by using Ag nanoparticles in membrane matrix. Moreover, modified membranes showed good ability in decrease of Escherichia coli growth rate.     

EFFECT OF ISO- AND TERE-PHTHALOYL CONTENT ON THE PORE SIZE AND THE PORE SIZE DISTRIBUTION OF AROMATIC POLYAMIDE RO MEMBRANES

Poly-m-phenylene-iso(x)-co-tere(100-xc)-phthalamide copolymers with different x values were synthesized and viscoelastic properties of the polymer solution were studied in the presence of lithium chloride nonsolvent additive in order to determine the size of the polymer aggregate in the solution. Reverse osmosis membranes were also prepared using the polymers synthesized above. The membrane performance was then tested for the separation of sodium chloride solute and reference organic solutes, in order to obtain the average pore size and the pore size distribution of the membrane. The data for the pore size were further used to calculate the length of the polymer segment in the noncrystalline region. An interesting correlation was found between the above length and the isophythaloyl content, x, of the copolymer.     

微通道反应器内硫酸钡沉积行为

硫酸钡是石油生产过程中经常遇到的难以清除的垢。在微通道反应器内对硫酸钡沉积行为进行较详细的研究。采用火焰原子吸收法和压差法分别测量钡浓度变化和微通道管段间的压力变化,考察微通道管长、流量、浓度及温度等因素对模拟油田水在微通道反应器内硫酸钡沉积行为的影响。实验结果表明,随着管路增长、流量增大、浓度增加,微通道中硫酸钡的沉积速率加快,沉积量增多,且呈非线性增加趋势,而温度升高使得微通道管路中离子扩散加快,硫酸钡沉积速率增大,但由于温度的小幅度升高并没有使硫酸钡溶度积发生明显变化,因此硫酸钡沉积量增加较少。采用扫描电镜观察管道内进出口处硫酸钡的结垢形态,验证了不同因素对管路沉积情况和结晶形态的变化。研究得出受结晶成核的影响,管道内硫酸钡的沉积结垢并非均匀简单的沉积过程,其晶粒形成可分为两个阶段,即成核阶段和晶体生长阶段。