纳米羟基磷灰石对重金属离子的吸附性能

电镀废水中存在大量的重金属离子会对环境造成极大污染。以钢铁冶炼矿渣作为原材料,采用共沉淀法制备了纳米羟基磷灰石。低结晶度的纳米羟基磷灰石呈现球形状,其粒径主要分布在约60 nm。纳米羟基磷灰石对铁离子、铜离子、锌离子和镍离子等金属离子具有良好的吸附性能,并且金属离子浓度随着电镀废水pH值的增大而减少。当电镀废水的pH值为9.0~11.0时,纳米羟基磷灰石处理过的电镀废水能够达到电镀污染物排放标准(GB21900-2008)。     

纳米改性羟基磷灰石的制备及对水中Cu2＋的吸附性能研究

以乙醇胺为改性剂,硝酸钙和磷酸氢二铵为原料采用沉淀法制备纳米羟基磷灰石.考察了改性剂乙醇胺用量、搅拌时间、羟基磷灰石用量、pH等因素对Cu2＋吸附的影响.实验结果表明,乙醇胺的加入有利于羟基磷灰石对Cu2＋的吸附,最佳吸附条件为乙醇胺2.5％,羟基磷灰石6g/L,pH为3,搅拌时间40 min,Cu2＋去除率为98.3％,处理后的含Cu2＋废水符合国家废水排放标准.     

电沉积制备羟基磷灰石-碳化硅复合涂层

采用电沉积技术在碳/碳复合材料表面制备出羟基磷灰石-碳化硅复合涂层,通过扫描电镜、x.射线衍射仪、能谱仪、傅里叶红外光谱仪研究了电解液浓度与电流密度对复合涂层形貌与组成的影响,采用粘接拉伸法测试羟基磷灰石-碳化硅涂层、羟基磷灰石涂层与基体的结合强度.结果表明:随着电解液浓度的降低,涂层的组成由磷酸氢钙转变为羟基磷灰石,晶体从大尺寸的片状逐渐转变为纳米级球状.随着电流密度的升高,涂层的钙、磷摩尔比逐渐升高,晶体向疏松的针状转变.选取适当的工艺参数,羟基磷灰石-碳化硅与基体结合强度高于羟基磷灰石涂层.     

纳米羟基磷灰石制备方法的研究进展

介绍了目前纳米羟基磷灰石的制备方法,重点阐述了化学沉淀法制备纳米羟基磷灰石的研究情况,并对纳米羟基磷灰石整个行业的发展做出了展望。     

羟基磷灰石/聚氨酯复合纳米纤维制备及其对重金属Cd~(2+)的吸附应用研究

随着工业的发展,水体重金属污染逐渐成为环境污染的重要组成部分,寻求环境友好型材料来治理水体重金属污染已成为当今环境科学研究的热点之一。以羟基磷灰石和聚氨酯为原料,利用静电纺丝技术制备羟基磷灰石/聚氨酯复合纳米纤维膜(HA/PU),并用其对水体中的镉污染物进行吸附研究。研究中采用了SEM、FT-IR、XRD和TGA等手段对复合纳米纤维膜的形貌、性能、结构等进行表征,并模拟进行了对含有重金属镉离子Cd~(2+)废水的吸附实验,系统考察了纳米纤维材料对Cd~(2+)吸附的影响。结果表明,在外加电压(18±2) k V、接触距离15. 0 cm、纺丝速度1. 5 m L/h的条件下,能够制得微观与宏观形貌较好的纳米纤维(膜),其中,HA/PU质量比为32/68的纤维膜对Cd~(2+)的吸附效果最佳,可短时间内达到18. 75 mg/g。     

纳米HAP粉末的制备技术及其研究进展

羟基磷灰石具有重要的医学价值,简要介绍了羟基磷灰石的结构和性质,并综述了目前国内外制备纳米羟基磷灰石的技术及其进展情况,通过对这些制备技术的概括比较,提出了纳米羟基磷灰石在制备、应用等方面的未来发展方向.     

模拟体液法制备纳米级羟基磷灰石

以制备羟基磷灰石粉体的其中一种反应体系为研究对象,用模拟体液法制备纳米羟基磷灰石粉体。在此实验过程中,研究了反应温度、反应浓度和反应时间对羟基磷灰石粉体合成的影响。结果发现,制备纳米级羟基磷灰石的最佳工艺条件为:反应温度为60℃,浓度为15SBF,反应时间为10h。在此工艺条件下,制备的羟基磷灰石粉体的微观形貌为球形颗粒,平均颗粒直径为30nm。     

碳羟基磷灰石除废水中六价铬的吸附性能研究

利用废弃蛋壳为原料,水热法合成碳羟基磷灰石(CHAP)吸附剂,用它去除含铬废水中六价铬,研究了pH、六价铬初始质量浓度、吸附时间等对吸附效果的影响.结果表明:常温下,溶液pH为3、碳羟基磷灰石用量为5 g/L时,对100 mL 50 mg/L的六价铬吸附速度较快,30 min基本上达到吸附平衡,去除率为98.3%,最大吸附量高达29.85 mg/g.用Langmuir和Freundlich方程拟合碳羟基磷灰石对六价铬的吸附等温式,相关系数分别为0.998 4和0.922 6,说明这两个方程都较好地描述吸附过程.通过氢氧化钠或硫酸浸泡和微波加热处理对吸附后的碳羟基磷灰石进行再生试验,再生率高达94.3%和94.8%.     

沉淀法制备羟基磷灰石反应条件控制研究

为了方便快速地获得高纯度羟基磷灰石,本研究以(NH4)2HPO4和Ca(NO3)2.4H2O为原料,利用沉淀法制备纳米级羟基磷灰石粉末。描述了制备过程。对温度、PH值、分散剂添加比例、钙磷比、烧结温度等反应控制条件进行了研究,对钙磷比及烧结温度做了详细的讨论。结果表明:此法可以得到分散性、均匀性好,纯度高、颗粒小、晶形完整的纳米级羟基磷灰石。     

沉淀法制备羟基磷灰石反应条件控制研究

为了方便快速地获得高纯度羟基磷灰石,本研究以(NH4)2HPO4和Ca(NO3)2·4H2O为原料,利用沉淀法制备纳米级羟基磷灰石粉末,并描述了制备过程。对温度、pH值、分散剂添加比例、钙磷比、烧结温度等反应控制条件进行了研究,并对钙磷比及烧结温度做了详细的讨论。结果表明,此法可以得到分散性、均匀性好,纯度高,颗粒小,晶形完整的纳米级羟基磷灰石。     

用超高速混合机及熔融共混法制备PP/纳米CaCO3复合材料

针对目前熔融共混法制备聚合物／纳米无机粒子复合材料研究中存在的纳米粒子分散的难题，采用特殊设计的新型超高速混合机（6000r/min)可以对纳米无机粒子进行有效的分散处理，即使在纳米CaCO3加入量大（体积分数12％，质量分数35％）的情况下，仍能较好地分散，复合材料的微观结构和性能都有较大改善。     

Improving hydrogen storage/release properties of magnesium with nano-sized metal catalysts as measured by tapered element oscillating microbalance

An effective catalyst doping method was developed for directly depositing nano-particles of various metal catalysts (palladium, platinum and ruthenium) on the outer surface of magnesium powders through a wet chemistry process. The catalyst-doped magnesium was characterized by powder X-ray diffraction (XRD), scanning electron microscope (SEM) and energy dispersive X-ray spectroscopy (EDS). Catalysts of nano-meter size were uniformly deposited on the outer surface of the magnesium particles. The hydrogen storage and hydrogen release properties of magnesium and catalysts-doped magnesium were measured in situ by the tapered element oscillating microbalance (TEOM), and also by the volumetric method. Both the hydrogen absorption and hydrogen release kinetics of magnesium were significantly improved by doping the nano-particle catalysts. Among the three metals-doped and examined, palladium showed the best catalytic effect. Upon doping 0.5 mol% nano-particle palladium, the hydrogen absorption and hydrogen release rates of magnesium increased 1 and 14 times, respectively, as revealed by the dynamic measurement of storage/release by TEOM, which indicated a strong catalytic effect.     

LSMCD法制备纳米(Pb,La)TiO3薄膜

研究了利用液态源雾化化学沉积(LSMCD)法制备纳米(Pb,La)TiO3薄膜的工艺. XRD和SEM分析表明:沉积4次,采用RCA热处理,在Pt/Ti/SiO2/Si基板上成功制备出具有钙钛矿结构的、晶粒粒径约60nm、厚度约180nm的纳米颗粒PLT薄膜.该方法既可以较精确的控制薄膜的化学计量比及掺杂浓度,又可采用控制超声雾化沉积的时间和次数来有效的控制膜厚及晶粒的大小.该工艺的沉积速率约为3nm/min.     

低压条件下纳米流体的沸腾换热特性

在不同低压压力和不同纳米流体浓度下对光滑传热面上的水基纳米流体的池内沸腾特性进行了试验研究.纳米流体由平均直径50 nm的氧化铜粒子加入去离子水中组成,没有加入任何添加剂.研究主要针对7.2 kPa到100kPa的压力区间和0.1%到2%的质量浓度区间内压力和颗粒浓度对光滑表面沸腾换热特性的影响,研究结果表明:压力对纳米流体的沸腾换热特性有强烈影响,沸腾换热系数和临界热流密度(CHF)强化率随着压力的降低而大幅度增加.纳米流体浓度对沸腾换热系数和临界热流密度(CHF)有重要影响,并且在质量浓度约1%附近存在一个最佳颗粒浓度.研究结果显示由与去离子水相比,质量分数为1%,压力为7.2 kPa的纳米流体在光滑表面上的沸腾换热系数和临界热流密度都得到了显著提高.     

Fabrication and Thermal Properties of Polyimide/Ba0.77Sr0.23TiO3 Nanocomposites

Polyimides (PIs) are considered to be one of the most important engineering materials. The nano-particle of barium strontium titanate (BST) with formulation of Ba_0.77Sr_0.23TiO₃ was synthesized by the sol-gel method. In this process, different contents of BST suspensions in polyamic acid (PAA) solution were imidized by heat treatment to form PI/BST nanocomposites. Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), simultaneous thermal analysis (STA), scanning electron microscope (SEM), and transmission electron microscopy (TEM) were used to characterize the structure and properties of the obtained nanocomposites. It was found that the BST nanoparticles sized 32–40 nm were dispersed homogeneously in the polyimide matrix without aggregation. The ζ potential of PI/BST 33 vol.% was decreased in contrast with that of the pure polyimide. The coefficient of thermal expansion (CTE) of PI/BST 33 vol.% was measured between 36°C and 600°C. CTEs comparison showed about 80% decrease in the CTE value of the nanocomposite in respect to the pure polyimide in a wider temperature range.     

In situ, high-pressure differential thermal analysis and ionic conductance of PMMA-based gels with and without TiO2 nano-particle filler

The transition behaviours of PMMA-based gels with and without nano-particle filler have been investigated at elevated pressures up to 0.9 GPa and in the temperature range 220-310 K. Both gels had molar ratios of 53.9:22:5.2:18.9 of ethylene carbonate (EC), propylene carbonate (PC), lithium perchlorate, PMMA, and one gel contained 8 wt.% TiO₂ nano-particles. The results show a sluggish transition between a low-pressure (high temperature) state and a high-pressure (low temperature) state. The nano-particle filler facilitates the kinetics of the transition, yielding a significantly lower transition pressure as well as a better homogeneity in the sample after a transition back to the low-pressure state. These results can be explained by a filler-induced increase of the nucleation rate, which yields smaller crystallites. The transition is observed also by differential scanning calorimetry and Raman spectroscopy at ambient pressure and is likely associated with crystallization of the EC-PC solvent. The logarithmic pressure derivative of the conductance and, consequently, the activation volume changes a factor of 3 as a result of the transition.     

壳聚糖的光敏改性及其胶束化行为

用1-(3-二甲氨基丙基)-3-乙基碳二亚胺盐酸盐(EDC)和N-羟基琥珀酰亚胺(NHS)在室温下催化壳聚糖(CTS)上的氨基与巯基乙酸的羧基反应生成酰胺键,得到侧基有巯基封端的CTS-HS,以PEG2 000为增溶剂在水溶液中与CTS-HS络合后冷冻干燥得到CTS-HS/PEG复合物。以偶氮二异丁腈(AIBN)为引发剂,甲基丙烯酰氧乙基肉桂酸酯(CEMA)和聚乙二醇甲基丙烯酸酯(MPEG)为共聚单体,加入含巯基的CTS-HS/PEG复合物为链转移剂进行自由基溶液聚合,得到壳聚糖光敏接枝物CTS-g-P(CEMA-co-MPEG)。用FTIR对壳聚糖光敏接枝物结构进行了表征。将壳聚糖光敏接枝物溶于水,在水溶液中直接形成胶束,用紫外-可见光分光光度计、Zeta电位仪、纳米粒度仪和透射电子显微镜研究了胶束的性质和形态。以白油为油相,研究了壳聚糖光敏接枝物的乳化性能。结果表明,壳聚糖光敏接枝物CTS-g-P(CEMA-co-MPEG)具有光敏性,可吸收波长在275 nm左右的紫外线,可在水溶液中自动形成粒径为120 nm左右的球形胶束,所得胶束在较宽的pH范围内均可稳定存在,并有较好的乳化性能。     

纳米填料改性聚氨酯研究进展

综述了纳米填料改性聚氨酯(PUR)近年来的研究进展,总结了普通纳米填料、有机改性纳米填料和纳米填料的分散方法对PUR力学性能的影响及纳米填料的改性机理研究,并对纳米填料改性PUR未来研究的重点方向进行了展望.     

Electrochemical impedance spectroscopy (EIS) study of nano-alumina modified alkyd based waterborne coatings

A nano-composite coating was formed by dispersing nano-Al₂O₃ as pigments in different concentrations, to a specially developed alkyd based waterborne coating. The nano-Al₂O₃ based composite coatings were applied on mild steel substrate by dipping. The dispersion of particles in coating system was investigated by using SEM and AFM techniques. The effect of addition of these nano-pigments on the electrochemical behavior of the coating was investigated in 3.5% NaCl solution, using electrochemical impedance spectroscopy (EIS). It was found that coating modified with higher concentration of nano-Al₂O₃ particles showed comparatively better performance as it was evident from pore resistance (R_p) and coating capacitance (C_c) values after 30 days of exposure. In general, the study showed an improvement in the corrosion resistance of the nano-particle modified coatings as compared to the neat coating, confirming the positive effect of nano-particle addition in coatings.     

碱性条件下甲醇阳极氧化碳载催化剂的性能

用化学还原法制备了碳载镍、银、金三种金属单质催化剂,并研究其对甲醇电催化氧化的活性.用X射线衍射光谱(XRD)、X光电子能谱(XPS)表征催化剂的晶相结构、表面组成及价态形式.XRD测试表明均得到了纯度较高的金属单质,催化剂粒径大小在5～11 nm之间,颗粒分布均匀.用循环伏安法测定了不同催化剂对甲醇的电催化氧化的活性...