热处理对纳米羟基磷灰石的相结构和粒度的影响

采用化学沉淀法合成纳米羟基磷灰石粉体,研究了热处理对纳米颗粒的相结构和粒度的影响,用FT-IR、XRD、TEM等对纳米羟基磷灰石粉体进行了表征.结果表明,沉淀法合成的纳米HA粉体含有少量CO32-离子,900℃煅烧后CO32-离子完全脱除.随热处理温度的提高,颗粒的形状由长条或针状变为球形,700℃热处理后可以得到晶化良好、平均直径50～55nm的球形纳米HA颗粒.     

具有自相似结构纳米银粉的制备及表征

采用液相化学还原法,以改性聚乙烯吡咯烷酮为分散稳定剂,用抗坏血酸还原硝酸银得到银溶胶,将银溶胶经离心分离、洗涤和真空干燥处理,得到规则球形纳米银粉.用动态光散射法激光粒度仪考察反应温度和溶液的pH值对纳米银粉粒度的影响.用扫描电镜(SEM)观察纳米银粉的形貌.用X 射线衍射(XRD)表征纳米银粉的晶体结构.研究结果表明,反应温度为40 ℃、w(PVP):w(AgNO3)=0.8、AgNO3浓度为0.24 mol/L、抗坏血酸溶液pH值=10,可得到具有至少3级循环套嵌自相似结构的规则球形纳米银粉;纳米银粉聚集体纯净无杂质,粒径在500～1 000 nm之间;粉体一次颗粒粒径为9～20 nm.     

超声波低温快速合成球形4A分子筛

在表面活性荆存在、低温条件下用超声波快速合成了性能优良的球形4A分子筛,并用xRD、IR、SEM和粒度分布等手段对合成的产物进行了表征.结果表明,所合成的分子筛的白度为95%,钙离子交换容量为318mgCaCO3/g干沸石,产物的平均粒径为1.64μm,粒度小于4μm的含量可达100%.此外,所合成的分子筛呈球形,更适合用作洗涤助剂.     

乙二醇溶剂中纳米铜镍复合粉的制备及表征

以聚乙烯吡咯烷酮(PVP)作为高分子保护剂,乙二醇为溶剂,在60℃恒温水浴中,用水合肼还原二价铜、镍盐,合成了铜镍纳米复合粉末.研究了铜镍前驱体浓度比对产物组成的影响,PVP加入量对合成铜镍复合颗粒尺寸的影响.对制得的样品用XRD,TEM进行了表征.结果表明:产物中的铜镍比随着反应物中铜镍比的增加而增加,铜镍复合纳米颗粒的粒度随着PVP浓度的增大而减小.因此,可以通过改变溶液中的Cu2 和Ni2 的比例以及PVP用量得到不同组成和粒度的铜镍复合纳米粉.     

微乳液法合成多孔纳米碳酸钙实验研究

主要介绍了采用氯化钙 -碳酸钠微乳液法合成纳米碳酸钙的工艺条件、方法和影响因素。实验方案中 ,采用能使Ca2 + 和CO3 2 -的传质延缓、容易从水中分离的吐温 80 -(Tween - 80 )为主导的表面活性剂。经过一系列实验对比分析 ,提出了生产纳米级碳酸钙的最佳试验工艺条件。另外 ,对所合成纳米CaCO3 进行粉晶衍射仪 (XRD)和透射电镜检测。结果表明 ,氯化钙 -碳酸钠微乳液法制备纳米碳酸钙纯度较高 ,平均粒径为 2 5nm ,具有良好的多孔结构     

用电石废渣制备纳米碳酸钙的研究

利用电石废渣制备得到了不同形貌的纳米级碳酸钙晶体。实验过程包括:电石废渣经过提纯后制成CaCl2溶液,然后在一定条件下和(NH4)2CO3溶液反应。在添加剂存在的情况下,制备出了纳米级碳酸钙晶体。并对反应条件如物料的浓度、反应温度、添加剂种类及作用机理进行探讨,确定了用电石废渣生产纳米碳酸钙的最佳方法,即控制温度为25℃,物料浓度为1.5mol/L,使用自制水溶性高分子添加剂,得到立方形碳酸钙,使用硼砂等可得到链状碳酸钙,添加醇类有机物可得到针状碳酸钙。     

溶胶-凝胶法制备PF-CaCO3预聚体功能性材料

将性能优良的纳米碳酸钙改性高分子材料-酚醛树脂制备酚醛树脂纳米复合材料,旨在得到一种可以取代部分价格昂贵的填充料及化学助剂,减少树脂的用量,节约能源等优点的一种功能性的填料。首先采用改性剂十二烷基甜菜碱制备纳米碳酸钙粉末,并通过添加入自制的酚醛树脂胶黏剂中,进而通过扫描电子显微镜(SEM)、红外光谱分析(FT-IR)、差示扫描量热/热失重(DSC-TG)分析,表明十二烷基甜菜碱的添加量2.5mL(占溶液质量的5%)较好,且得到的PF-CaCO3预聚体均一,热稳定性好。     

用异醇铝溶液燃烧化学沉积α-Al2O3纳米晶

本文提出了一种制备高性能纳米陶瓷粉体的新方法.将异醇铝溶液溶于易燃溶剂中配制成初始反应溶液,通过组合喷嘴让该溶液雾化并穿过氧-乙炔火焰,通过化学燃烧制备纳米α-Al2O3粉体.通过完全燃烧计算、雾化试验和燃烧试验,确定了溶液喷口、雾化剂(O2)喷口和氧-乙炔喷口的压力和流量的工艺参数.扫描电镜,激光测粒仪,高分辨透射电镜分析表明,用上述方法制备的纳米α-Al2O3以球形和六方棱柱为主,含极少量菱面体,颗粒尺寸为20～30nm,粒度均匀细致且分散性好.     

纳米氧化锌的固相合成

以七水硫酸锌和无水草酸钠为原料,用室温固相化学反应首先合成出前驱物草酸锌,经400℃分解3h,得到产物纳米氧化锌。用X-射线粉末衍射和透射电镜对产物的组成、大小、形貌进行表征。结果表明,产物纳米氧化锌为粒度分布均匀的球形六角晶系结构,平均粒径为28nm。     

纳米碳酸钙湿法表面改性的研究

利用季铵型阳离子表面活性剂对纳米碳酸钙进行了湿法表面改性。对湿法改性前后的纳米碳酸钙进行了红外光谱(FTIR)、X射线衍射(XRD)及透射电镜(TEM)分析。采用Zeta电位、分散体系浊度、沉降体积、表观粘度等分析方法对改性前后纳米碳酸钙在水中的界面行为进行评价。另外,通过激光粒度仪对改性前后纳米碳酸钙分散液的粒度分布进行了测定。实验结果表明,经湿法表面改性后,纳米碳酸钙在水中的润湿性及分散性有很大改善。     

仿生矿化的研究Ⅰ．文石型碳酸钙的合成

在聚乙二醇（ＰＥＯ）存在下，ＣａＣｌ２和Ｎａ２ＣＯ３反应生成了类似红鲍鱼壳的含有ＰＥＯ的碳酸钙──高聚物复合材料。Ｘ－衍射和电镜照片显示，它有两种微观结构：外层为文石型和方解石型结构，内层为针状文石型结构。热重分析表明，该材料中含有３％左右ＰＥＯ。结果说明，聚合物对碳酸钙晶核的形成和晶体的生长有很大影响，并对其形成机理进行了初步探讨。     

高精度扫描隧道显微镜对纳米碳酸钙特性的研究

用高精度IPC-205B型扫描隧道显微镜测得纳米碳酸钙的扫描隧道谱。该隧道谱表明,纳米碳酸钙具有半导体性质,与普通碳酸钙相比,其导电性能有了明显改善。由纳米碳酸钙隧道谱得出纳米碳酸钙的禁带宽度为0．4eV,比半导体硅的禁带宽度1.1eV的低。     

添加剂对制备MLCC电极用超细铜粉形貌的影响

采用葡萄糖预还原,后阶段以水合肼作为还原剂,在液相中还原CuSO4的方法制备超细铜粉。研究了聚乙烯吡咯烷酮(PVP)、NH4Cl、NaOH对超细铜粉粒度和形貌的影响。结果表明,制得的铜粉形貌呈球形,粒径均匀可控,分散性好。加入适量的PVP有助于超细铜粉粒径均匀和形貌规范;NH4Cl可使铜粉的粒径变小,当Cu与NH4Cl的摩尔比为1∶1时铜粉的形貌会由类球形向正方体转变;微量的NaOH能有效消除超细铜粉表面的棱峰,使铜粉的表面更圆滑,同时也可以使铜粉粒径变小。     

Chemiluminescence determination of chlorinated volatile organic compounds by conversion on nanometer TiO2

A novel method based on conversion of chlorinated volatile organic compounds (CVOCs) to chlorine using a new type of column packed with nanometer TiO2 coupled with chemiluminescence (CL) has been developed for determination of them in workplace air. CVOCs are converted to chlorine by nanometer TiO2 at 220 degrees C. The Cl2 that is produced is selectively enriched on the column and subsequently released from the column at 600 degrees C. The Cl2 that is released is determined using a postcolumn CL detector. The CL intensity was linear with CCl4 in the range of 0.1-380 ppm, and the detection limit was 40 ppb (S/N = 3). Higher sensitivity could be acquired by using a larger volume of enrichment A similar procedure could be used for the determination of other CVOCs. CL intensities of CH2Cl2, CHCl3, and CCl4 at the same concentration increased in the order CH2Cl2 < CHCl3 < CCl4. The method has been successfully applied to the determination of CCl4 in workplace air, where 0.15-150 ppm CCl4 would be detected. The possible mechanism for the long lifetime of the column packed with nanometer TiO2 was tested using Raman spectrometer, X-ray powder diffraction, transmission electron microscopy and X-ray photoelectron spectroscopy. The results showed that the column packed with nanometer TiO2 could be operated in the reversible mode for determination of CVOCs under the present conditions. The method would be potentially applied to the analysis of other chlorinated compounds in environment, such as persistent organic pollutants.     

Dendritic Deposition of NH_4CI Crystals with Free Surface as Simulations of Surface Solidification of Materials

As a simulation of surface solidification of materials,quasi-two dimensional dendritic deposition ofammonium chloride(NH_4Cl)crystals from an aqueous solution film with free surface byvapourization was investigated by the in- situ observation technique.The depositing morphologiesof NH_4Cl crystals are faceted and of growth laws differing from the three-dimensional case.Underlow supersaturation,faceted dendrites formed,whereas the anisotropy in growth kinetics decreaseswith the increase of supersaturation.When vapourizing rate(supersaturation)is not very low,oscillations of growth rate.tip-radius and second arm spacing of the dendrites were observed.It issuggested that this dynamic phenomenon is attributed to the correlation between theconvection-transfer effect induced by the surface tension gradient of solution film.and the drivingforce for deposition.     

纳米粒子的分散状态对聚丙烯结晶行为的影响

用普通熔融共混与低剪切应力场下聚合物/纳米粒子的分散共混方法制备出聚丙烯/无机纳米粒子复合材料,采用示差扫描量热法(DSC)与偏光显微镜(PFM)对试样的结晶行为进行研究发现:在填充粒子含量相同情况下,均匀分散的纳米粒子可以较大提高聚丙烯的结晶温度,结晶速率,使晶体尺寸减小,而普通熔融共混制备的试样中,纳米粒子虽然也一定程度增加了聚合物的结晶温度,却并不改变晶体的尺寸。结果表明,当制备聚合物/纳米粒子复合材料时,纳米粒子在基体中的分散程度极大地影响聚合物基体的结晶行为。     

SiO2/CaCO3纳米复合粒子填充改性聚丙烯

通过简单的工艺条件和步骤制备S iO2包覆C aCO3的核壳结构纳米复合粒子,采用硅烷偶联剂对其和纳米S iO2实心粒子进行表面改性处理,并用处理后的两种粒子分别对聚丙烯进行填充改性,然后比较其对复合材料力学性能的影响。结果表明,利用纳米S iO2/C aCO3复合粒子填充改性聚丙烯,可同时达到增强、增韧的目的,而且对材料力学性能的改性效果与纳米S iO2实心粒子的改性效果相近。     

Investigation on the sonocatalytic degradation of parathion in the presence of nanometer rutile titanium dioxide (TiO2) catalyst

The nanometer rutile titanium dioxide (TiO2) powder was adopted to act as the sonocatalyst after treatment of high-temperature activation and the ultrasound of low power was used as an irradiation source to induce heat-treated TiO2 powder performing sonocatalytic degradation of parathion. Although there are many factors influencing sonocatalytic degradation of parathion, the experimental results demonstrate that the optimal degradation condition of parathion can be obtained when the experimental conditions such as initial concentration of 50 mg/L parathion, addition amount of 1000 mg/L nanometer rutile TiO2, ultrasonic of 30-50 kHz frequency and 50 W output power, acidity of pH 10.0 and temperature of 20 degrees C are adopted. The degradation ratio of parathion surpassed 90% within 120 min ultrasonic irradiation in these optimal experiment conditions. The total degradation process of parathion has been monitored by UV-vis spectra and ion chromatography. At last, the parathions in aqueous solution are completely degraded and become some simple inorganic ions such as NO3(-), PO4(3-), SO4(2-), etc. In addition, the sonocatalytic activities of reused TiO2 catalysts were also studied and found to decline gradually along with the reused times. In this paper, the research on sonocatalytic degradation kinetics was also been performed and found to follow pseudo first-order reaction. All experiments indicated that the sonocatalytic method in the presence of nanometer rutile TiO2 powder was an advisable choice for the treatments of non- or low-transparent organic wastewaters in future.     

微悬浮法CaCO3表面接枝PMMA及其在PVC中的应用

在水介质中,超声作用下用油酸对纳米碳酸钙进行表面修饰,再以微悬浮原位聚合法用PMM A进行接枝包覆,成功制备了PMM A/C aCO3复合粒子。借助透射电镜(TEM)、红外光谱(FT-IR)、热失重(TG)等分析手段对复合粒子的形态结构进行了表征。实验结果表明,油酸可通过羧酸盐的形式吸附于碳酸钙粒子表面,一定量PMM A通过油酸分子的不饱和双键接枝于碳酸钙粒子表面。将所得PMM A/C aCO3复合粒子与PVC共混制得PVC/PMM A/C aCO3复合材料。复合材料的TEM照片表明,C aCO3粒子非常均匀地分散在PVC基体中,两相界面模糊。随着PMM A/C aCO3纳米复合粒子用量的增加,复合材料的强度和韧性同时提高。当复合粒子用量高于12%时,复合材料的冲击强度可提高3倍,而拉伸强度下降很少。     

Effects of calcium-based sorbents on PCDD/F formation from pentachlorophenol combustion process

Calcium-based sorbents are widely employed to reduce the acidic gases emission from combustion processes, and also have effects on trace organic pollutants formation and emission. Batch experiments were conducted to investigate the effects of calcium-based sorbents on pentachlorophenol (PCP) forming PCDDs/Fs during high temperature combustion processes. The results indicated that highly chlorinated PCDD/F homologues were the predominant dioxin products from PCP thermo decomposition, and only minor increasing of PCDDs happened when Ca/Cl ratio was lower than 1, while a major jump occurred when Ca/Cl ratio increased from 1 to 2. The CaO addition clearly promoted the production of all chlorinated dibenzo-p-dioxins homologue and 4-7DFs homologue. Comparison of total PCDD/F emission and its I-TEQ for three different calcium-based sorbents addition (CaO, CaCO3, basic fly ash) indicated that CaO and fly ash containing CaO had almost the same promotion effects on PCDDs/Fs originated from PCP, while CaCO3 inhibit PCDD/F formation greatly with inhibition efficiency up to 70%. Such effects may be partly proved by the observed clearly different micro-surface structures of their reaction residues. The mechanism of CaO on condensation and dechlorination reactions for PCP forming PCDDs and acid-base interaction were proposed to speculate the promotion effects of CaO, and the reaction precedence was used to speculate the inhibition effects of CaCO3 on PCDDs/Fs originated from PCP. The results of the present paper might be useful for the industrial application of calcium-based sorbents to control PCDD/F emission.