改性牡蛎壳对废水中磷吸附性能的研究

采用高温煅烧对天然牡蛎壳进行改性处理,并初步研究了天然牡蛎壳和经过不同煅烧温度处理后的牡蛎壳样品对废水中磷的吸附作用。采用TGA-DTA、XRD、SEM分别对天然牡蛎壳的热分解历程和不同温度烧结后所得的改性牡蛎壳的相组成和微观结构进行研究。结果表明:在相同的条件下,天然牡蛎壳粉对废水中磷的吸附效果较差;牡蛎壳经过650~800℃煅烧处理后,其对废水中磷的吸附性能明显提高。当煅烧温度为750℃时,牡蛎壳煅烧物对废水中磷的去除率可以达到99%。因此牡蛎壳经过750℃煅烧处理后,是一种固磷性能较好的新型钙基除磷剂。     

牡蛎贝壳/纳米Cu2O复合材料的制备及性能研究

纳米Cu2O是一种新型半导体光催化剂,在使用时存在容易团聚、难以回收利用等问题。通过原位水解法,采用废弃的牡蛎贝壳粉为载体固定生成的纳米Cu2O,成功制备出牡蛎贝壳/纳米Cu2O复合材料。通过X射线粉末衍射(XRD)、扫描电子显微镜(SEM)及能谱(EDS)和紫外-可见光漫反射等测试手段对材料进行了表征,发现Cu2O颗粒能够紧密地负载在900℃煅烧的牡蛎贝壳粉表面,且颗粒呈球状,平均粒径为37.3nm,禁带宽度为2.01eV,对可见光具有良好的吸收,拓宽了对太阳能的利用范围。研究还表明该复合材料具有良好的杀菌性能。     

牡蛎壳为原料制备医用CaCO3/HA复合生物材料

以牡蛎壳为原材料,通过水热法制备了碳酸钙(CaCO3)/羟基磷灰石(HA)复合材料,拟达到降低HA生产成本并改善其降解性能的目的。通过物相分析和SEM、TEM观察发现制得的CaCO3/HA复合材料呈现片层状,其微观形貌呈现纳米颗粒状。实验通过控制钙、磷元素的投料比例制备了HA含量为20%、40%、60%的三种CaCO3/HA复合材料(20%HA、40%HA、60%HA),通过ICP测试计算得出HA的实际含量为17.52%、34.30%、43.24%。随着HA含量的增加, CaCO3/HA复合材料的比表面积和热稳定性显著提升。体外降解实验结果表明,三种不同HA含量的复合材料在PBS模拟体液中14d的降解率分别为15.2%,12.0%和10.8%,降解率随HA比例的增高而降低。这些结果表明:水热法合成CaCO3/HA复合材料可通过钙、磷元素的投料比例来调控HA的转化率,进而调控CaCO3/HA复合材料的降解速率,实现其在骨科领域的潜在应用。     

纳米CaCO3/TiO2复合粒子的制备

首先制备出分散性能良好的Ti(OH)4胶体溶液,然后将胶体溶液加入到以十二烷基苯磺酸钠为分散剂的纳米CaCO3水性悬浮液中;通过改变体系的温度、pH值等参数破坏Ti(OH)4胶体粒子的稳定性,导致Ti(OH)4胶体粒子沉积在纳米CaCO3表面从而形成具有核-壳结构的纳米CaCO3/TiO2复合粒子,沉积过程中纳米CaCO3可起成核剂作用.所制备的纳米CaCO3/TiO2复合粒子以球形或近球形为主,粒度均一,且壳层TiO2粒子的尺寸为5～8nm.     

利用牡蛎壳和废玻璃粉制备废水除磷吸附材料的研究

以牡蛎壳和废玻璃粉为主要原料制备了空心管状型体废水除磷材料,探讨了在500～650℃不同预烧温度、不同样品配方及与废水接触不同时间下样品的废水除磷效果,从而选择最佳制备条件.采用XRD及SEM表征样品的微观结构及组成,采用磷钼蓝分光光度法测定废水中磷的含量.结果表明,含废玻璃粉20%、牡蛎壳80%的样品在600℃煅烧时除磷效果最好,12天后除磷率达到99%;XRD分析显示此时样品主要由3种晶相组成,CaCO3、SiO2和CaO,说明在此温度下牡蛎壳中的部分CaCO3已经分解为CaO.     

牡蛎壳粉为载体的TiO2催化超声降解偶氮品红溶液的研究

采用实验室合成的以牡蛎壳粉为载体的TiO2作为催化剂,以偶氮品红超声降解反应为模型,研究了各种因素对偶氮品红超声降解反应的影响.结果表明在金红石型纳米TiO2作用下超声降解偶氮品红的效果明显优于锐钛型纳米TiO2和单纯使用超声波的情况.超声波频率25 kz,输出功率50 w,催化剂用量600mg/L,pH为2.0,偶氮品红水溶液初始浓度20mg/L的条件下,2h左右降解率即可达到80%以上,COD的去除率也可达到了90%.因此,金红石型纳米TiO2催化超声降解有机污染物的方法具有很好的应用前景.     

纳米CaCO_3对CPE/ACR共混增韧PVC力学性能的影响

研究了纳米碳酸钙(CaCO_3)对氯化聚乙烯(CPE)/丙烯酸树脂(ACR)/聚氯乙烯(PVC)共混体系力学性能的影响,并通过动态机械热分析(DMA)和扫描电子显微镜(SEM)对共混体系的力学松弛行为、纳米CaCO_3在CPE/ACR/PVC共混体系中的分散状态及共混体系的断面形貌特征进行了表征。结果表明,纳米CaCO_3能够显著提高CPE/ACR/PVC共混体系的冲击性能,而不降低共混体系的强度。加入纳米CaCO_3后,共混体系的低温损耗(tanδ)峰强度显著增大,并且与冲击强度的变化具有很好的对应性。SEM观察发现,8 phr纳米CaCO_3可在CPE/ACR/PVC基体中形成纳米尺度的均匀分散,加入过多纳米CaCO_3则会出现明显的团聚。     

核壳结构型纳米CaCO3-SiO2.nH2O复合粒子的制备

在搅拌槽式反应器中,以用超重力法合成的纳米 ＣａＣＯ３和 Ｎａ２ＳｉＯ３为原料,用溶胶－凝胶技术制备具有核壳结构的纳米 ＣａＣＯ３－ＳｉＯ２·ｎＨ２Ｏ复合粒子　用 ＸＰＳ、 ＴＥＭ、 ＸＲＤ等方法对粒子的化学组成、形貌、晶型等作了分析和表征     

针状纳米碳酸钙的制备研究

采用鼓泡碳化法，以无机酸A为添加剂，通过对反应温度，反应物浓度，气体流量和气体分布板孔状径大小等各影响因素的控制，得到制备针状纳米碳酸钙的优化工艺条件，最终制得了平均粒径为20nm，长径比约为18,且分散性能良好的纳米碳酸钙，并用TEM和XRD对产物粒子进行了表征。     

耐热性聚酰亚胺复合材料的制备

以均苯四甲酸二酐、4,4'-二氨基二苯基醚、N,N'-二甲基乙酰胺为主要原料合成聚酰亚胺树脂,通过对比固化后树脂的吸水性能、耐热性能,表明:复合材料比纯聚酰亚胺具有良好的耐热性能,更低的吸水性能.并研究了溶剂体系、反应温度、时间、投料比和总固含量等因素对所得聚酰胺酸特性黏度的影响.     

Thermal decomposition of calcium carbonate polymorphs precipitated in the presence of ammonia and alkylamines

Precipitated calcium carbonate was obtained by CO₂ bubbling in CaCl₂ solution. Ammonia and alkylamines were used to enhance CO₂ absorption and control the polymorphic phases. Vaterite and calcite mixtures were obtained, mainly vaterite in ammonia and mono-methylamine and mostly calcite in tri-methylamine environment. The thermal decomposition of precipitated calcium carbonate leads to high purity CaO. During the thermal decomposition the vaterite to calcite transformation was noticed but the final spherical shape of vaterite was maintained. As the use of CaO as catalyst in biodiesel synthesis may recommend a spherical shape and high contact surface, a precipitated calcium carbonate, rich in vaterite phase, may be a good precursor for CaO catalyst preparation.     

钛熔模精铸用氧化物陶瓷型壳制壳工艺的研究

针对钛的特性合理地选择了制壳材料的种类,研究了粉液比等工艺参数对涂料的悬浮性,涂层厚度的影响,合理地选择了面层,邻面层及背层涂料的干燥温度,湿度和时间,并确定了适宜的微波脱蜡工艺,在不同粉液比条件下,研究了室温及不同焙烧温度对型壳抗弈强度的影响,从而确定了最佳粉液比和焙烧工艺参数,采用优化的制壳工艺参数制备的型壳,内表面光洁,无裂纹等缺陷,采用水冷铜坩埚真空感应炉进行熔炼和浇注,得到了外观较好的铲     

Processing of bovine hydroxyapatite (HA) powders and synthesis of calcium phosphate silicate glass ceramics using DC thermal plasma torch

In the present work, hydroxyapatite (Ca₁₀(PO₄)₆(OH)₂) was prepared from bovine bones with calcination method (up to 850 °C).The calcinated hydroxyapatite was powdered (30-40 μm) using a mechanical grinder; the particles were highly irregular in shape with sharp edges, angular, rounded, circular, dentric, porous and fragmented morphologies. The irregular shaped calcinated hydroxyapatite was plasma processed to produce spherical powders for thermal spray coating applications. More over; calcium phosphate silicate glass ceramics was produced by plasma melting of ball milled hydroxyapatite-borosilicate glass (50 wt.%) mixture. The samples were characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffractometer (XRD) and energy dispersive X-ray analysis (EDX). The morphology was determined using scanning electron (SEM) and optical microscopy (OM). The microhardness, density and porosity measurements for the synthesized samples were made.     

Preparation and characterization of novel diatomite/ground calcium carbonate composite humidity control material

Three kinds of novel diatomite/ground calcium carbonate composite humidity control materials were prepared with different calcination temperatures using diatomite and ground calcium carbonate (GCC) as raw materials. The microstructure and morphology properties of samples were studied by nitrogen gas adsorption, mercury intrusion porosimetry (MIP) and fractal dimensions on the basis of gas adsorption isotherms with FHH methods. Fourier transform infrared spectroscope (FTIR), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used to characterize the mineral composition and surface properties. Furthermore, X-ray diffraction (XRD), thermo-gravimetry and differential scanning calorimetry (TG-DSC) were used to analyze the formation mechanism of composite material. It was indicated that DG750 showed the better moisture adsorption performance. The 72 h moisture adsorbed amount of DG750 reached 11.66%, 8.81% and 8.00% at 98%RH, 85%RH and 75%RH, respectively, which improved about 0.46, 0.54 and 0.53-fold as those of diatomite. The hydrophilic calcium silicate, calcium oxide and calcium hydroxide were formed in the DG750 during the calcinations process. As compared with the raw materials, the content of mesoporous component increases in the DG750, which is in favor of capillary condensation and improving moisture adsorption ability.     

Synthesizing a composite material of amorphous calcium carbonate and aspartic acid

A composite material of amorphous calcium carbonate and aspartic acid (Asp) was synthesized using a highly concentrated solution of calcium aspartate: a new approach. A transparent and amorphous solid with approximately 1 mm thickness was obtained. UV-vis transmittance spectrum of the composite shows no characteristic absorption in visible region. A Raman spectrum of the composite revealed a peak assigned to the symmetric stretching of carbonate ion. This study demonstrated that amorphous calcium carbonate could be stabilized using not only organic artificial macromolecules but also using Asp, a small biomolecule. This result is expected to engender development of new biomimetic materials.     

无定形碳酸钙的稳定性和结晶转化过程研究进展

无定形碳酸钙在具有多级结构和优异力学性能的碳酸钙矿物的形成过程中起着至关重要的作用。生物体可以非常精确地调控无定形碳酸钙的结晶转化过程,而化学合成的无定形碳酸钙通常很不稳定。因此,从化学的角度研究无定形碳酸钙的稳定机理以及无定形碳酸钙结晶转化过程,对于理解以无定形物相为前驱体的生物矿物形成过程具有非常重要的意义。综述了无定形碳酸钙的本征特性,以及环境因素和添加剂对其稳定性和结晶转化的影响,阐述了无定形碳酸钙在晶体生长过程中的作用,讨论了该领域对材料结构和特性调控方面的启示。     

Overview of the amorphous precursor phase strategy in biomineralization

It was assumed for a long time that organisms produce minerals directly from a saturated solution. A few exceptions were known, including the well documented mineralized teeth of the chiton. In 1997 it was demon-strated that sea urchin larvae form their calcitic spicules by first depositing a highly unstable mineral phase called amorphous calcium carbonate. This strategy has since been shown to be used by animals from other phyla and for both aragonite and calcite. Recent evidence shows that vertebrate bone mineral may also be formed via a precursor phase of amorphous calcium carbonate. This strategy thus appears to be widespread. The challenge now is to understand the mechanisms by which these unstable phases are initially formed, how they are temporarily stabilized and how they are destabilized and transform into a crystalline mature product.     

碳酸钙晶须的制备与应用研究进展

文石相碳酸钙是一种新型环保晶须材料,由于造价低廉,使其具有很强的市场竞争力.综述了国内外在文石相碳酸钙晶须的制备和应用方面的研究进展,特别是国内碳酸钙晶须的开发现状和性能特点,分析了其市场前景.     

某产品深孔壳体加工工艺技术改进

目的某产品壳体为关键重要零件,壳体内承载大部分零部件,壳体加工精度的高低,直接影响产品设计指标,壳体内孔较深,且壳体壁厚差设计精度要求相对较高,加工后部分壳体出现壁厚差超差问题,影响产品加工质量,为此进行工艺技术改进,解决深孔壳体加工壁厚差超差问题。方法通过改进壳体预压型、冲拔工艺,改变拔伸毛坯冷却方式,增加壳体内膛喷砂工序,提高壳体内膛冲拔加工精度;改进壳体机加工艺及装夹定位工艺基准,改进夹具设计结构,使加工装夹定位工艺基准统一,消除多次装夹累计误差。结果通过工艺技术优化改进,解决了壳体加工壁厚差超差问题。结论提高了壳体加工精度,降低了壳体加工废品损失,节约了生产成本。     

基质调控碳酸钙生物矿化过程及其体外模拟的研究进展

生物体内碳酸钙的矿化过程受有机基质的调控。本文综述了基质蛋白和各类模型基质调控下碳酸钙矿化的研究进展。有机基质提供碳酸钙成核和生长的模板,调控碳酸钙晶体的结晶学取向、晶型和形貌,使形成的碳酸钙晶体具有特定的理化性质。同时,碳酸钙也可影响有机基质的微观结构。