Sol-gel Preparation and Preliminary in vitro Evaluation of Fluorapatite/Hydroxyapatite Solid Solution Films

Fluorapatite/hydroxyapatite solid solution has better biological properties than other apatites, especially used as films or coatings. In this work, sol-gel preparation and in vitro behavior of fluorapatite/hydroxyapatite solid solution films on titanium alloy were investigated. Ca(NO3)2·4H2O and PO(OH)K(OEt)3-x. were selected as precursors, and hexafluorophosphoric acid (HPF6) was used as a fluorine containing reagent. The Ca and P precursors were mixed with HPF6 to keep the Ca/P molar ratio 1.67. The mixtures refluxed for 12 h were used as dipping sols for the preparation of the films. The phase of the films obtained at 600℃ was apatite. The F contents in the films increased with the concentrations of HPF6 in the dipping sols. The solid solution films were shown to have better stability than hydroxyapatite films, and a reasonably good bioactivity in the in vitro evaluation.

Utilization of DTAB as a collector for the reverse flotation separation of quartz from fluorapatite

Reverse flotation desilication is an indispensable step for obtaining high-grade fluorapatite. In this work, dodecyltrimethylammoni- um bromide (DTAB) is recommended as an efficient collector for the reverse flotation separation of quartz from fluorapatite. Its collectivity for quartz and selectivity for fluorapatite were also compared with figures corresponding to the conventional collector dodecylamine hydrochlor- ide (DAC) via microflotation experiments. The adsorption behaviors of DTAB and DAC on minerals were systematically investigated with surface chemical analyses, such as contact angle determination, zeta potential detection, and adsorption density measurement. The results re- vealed that compared to DAC, DTAB displayed a similar and strong collectivity for quartz, and it showed a better selectivity (or worse col- lectivity) for fluorapatite, resulting in a high-efficiency separation of the two minerals. The surface chemical analysis results showed that the adsorption ability of DTAB on the quartz surface was as strong as that of DAC, whereas the adsorption amount of DTAB on the fluorapatite surface was much lower than that of DAC, which is associated with the flotation performance. During the floatation separation of the actual ore, 8wt% fluorapatite with a higher grade can be obtained using DTAB in contrast to DAC. Therefore, DTAB is a promising collector for the high-efficiency purification and sustainable utilization of valuable fluorapatite recourses.

Densification and Microstructure of Fluorapatite Sintered with Alkaline and Alkaline-Earth Additives

A study was performed to investigate the effect of some selected sintering additives on the densification and microstructure of fluorapatite (FAp, Ca10(PO4)6F2). The sintering aids, used for improving the material densification at lower than 1080℃ temperature, were classified according to their cations as alkaline such as Li2CO3, NaF, Na2CO3, Na3PO4, KCl, K2CO3, and alkaline-earth such as CaF2, CaCl2 and MgCl2. Amounts of 0.1;1 and 3 wt% were vigorously homogenized with FAp powders then the solid mixture was pressurelessly sintered under argon flow with 10℃ .?min-1 heating and cooling speed. The density of each sintered material was determined by calculation of the pellet dimension and weight, the crystalline phases were identified using X-ray diffraction (XRD) and the phase morphology was examined by scanning electron microscopy (SEM). The dependence of densification and microstructure on sintering temperature range 900℃ - 1000℃ and amount of sintering aids was studied. It was found that all sintering additives were able to ameliorate the sintrability of the material at temperatures 900℃ and 1000℃. Maximums of about 96% were reached with adequate amounts and sintering temperatures. An exception was found with KCl which had no effect on the density. The microstructures of sintered specimens strictly follow the densification ratios and the sintering mechanism depended on the melting point of the additive.

Elaboration and characterization of alumina - fluorapatite composites

Alumina and fluorapatite powder were mixed in a wet medium in order to elaborate biphasic ceramics composites. The effect of fluorapatite addition (26.5 wt%) in the densification and the mechanical properties of the alumina matrix were measured. The phase developments have been systematically analysed by scanning electronic microscopy, X-ray diffraction, Infrared spectroscopy and 31P and 27Al magic angle scanning nuclear magnetic resonance. The Brazilian test was used to measure the mechanical resistance of alumina - 26.5 wt% fluorapatite composites. The densification and strength rupture of composites increase versus sintering temperature and holding time. At 1600°C, the composites densities reached 85% and the rupture strength was about 22 MPa. Also, the composites sintering at 1500°C for 5 hours provides samples with similar density and having higher mechanical resistance, above 26 MPa. For longer holding times, the mechanical properties were hindered by the exaggerated grain growth and the formation of intragranular porosity. From 1400°C, the characterization of the alumina - 26.5 wt% fluorapatite composites indicates the formation of calcium aluminates.

Synthesis of Co-Cr-Mo Fluorapatite Nano-Composite Coatings by Pulsed Laser Deposition for Dental Applications

Aim: The study was to fabricate FA nanopowder/Co-Cr-Mo dental alloy nanocomposite using pulsed laser deposition (PLD), and to evaluate bioactivity properties on simulated body fluid. Methods: In this work, the FA nanopowder was prepared by mixing calcium hydroxide (Ca(OH)2), phosphorouspent oxide (P2O5) and calcium fluoride (CaF2) in a planetary high energy ball mill using zirconium vial. Fluorapatite (FA) nanopowder was processed in the form of pellet for pulsed laser deposition process. The Co-Cr-Mo alloy was coated with FA nanopowder which was approximately 35 - 65 nm at various laser energy, pressure and time. The X-ray diffraction (XRD) was used to analyze phase, crystallinity and size distribution of Co-Cr-Mo/FA nanocomposite. The surface analysis was by scanning electron microscopy (SEM), Atomic Force microscopy (AFM) and Energy dispersive spectroscopy (EDS). Results: From the results obtained, It was shown that FA nanopowder deposited on Co-Cr-Mo alloy was stable during 14 days of incubation on simulated body fluid. It was also observed that the FA nanopowder coated on the surface of the alloy was still intact after the deposition process, which indicated the bioactivity and biocompatibility of the material. Conclusions: The fabrication of FA nanocomposite based dental alloys (Co-Cr-Mo) using PLD was done successfully. This was confirmed by various characterization techniques, which included XRD, AFM, SEM and EDS.

Facile Synthesis of Nitriles and Amides from Aldehyde over Heterogeneous Reusable Copper Fluorapatite (CuFAP) Catalyst under Neat Reaction Condition

A new robust heterogeneous, versatile, an environmentally benign, eco-friendly, recyclable CuFAP catalyst has been developed for the direct synthesis of nitriles and amides from aldehydes at 100°C for 6 h and 4 h, respectively, under neat reaction condition using hydroxylamine hydrochloride in the presence and the absence of tosyl chloride, respectively. Also the recyclability of catalyst as well as influence of solvents, additives on catalysts performance was investigated. The protocol can be considered as an alternative to conventional method for the synthesis of nitriles and amides in good to excellent yields. A highlight of our protocol is the easy separation of catalyst from reaction mixture, hence the catalyst is reused several times without significant loss of its catalytic activity.

Sodium-Modified Fluorapatite: A Mild and Efficient Reusable Catalyst for the Synthesis of <i>α,α</i>’-Bis(Substituted Benzylidene) Cycloalkanones under Conventional Heating and Microwave Irradiation

A versatile and environmentally friendly method for α,α’-bis(substituted ben-zylidene) cycloalkanones has been developed using a heterogeneous catalysis technology. We have synthesized a series of the α,α’-bis(substituted benzylidene) cycloalkanones, a biologically important class of compounds, via the cross aldol condensation between arylaldehydes and cycloketones using sodium-modified fluorapatite (Na/FAP) as a highly efficient solid catalyst under conventional heating in aqueous media and solventless conditions under microwave. Catalyst reuse, ease of separation of the pure product, and high yields are some of the unique features of this process. Shorter reaction times (4 - 7 min) and higher yields (80% - 94%) were achieved under microwave irradiation conditions.

磷矿反浮选回水体系中难免离子对浮选行为的影响

这是一篇矿业工程领域的论文。氟磷灰石及白云石在反浮选酸性介质中易溶解出Ca^(2+)及Mg^(2+),并在回水循环过程中存在“累积效应”,对浮选指标造成不良影响。本实验以氟磷灰石、白云石及石英三种单矿物为研究对象,研究了不同循环次数的回水对三种单矿物浮选回收率的影响,研究表明,当pH值为5,循环次数达到3次后,白云石与氟磷灰石回收率差值由72.21%降低为64.19%,石英的回收率基本维持10%左右;而循环次数达到5次时,白云石与氟磷灰石回收率差值略微回升为69.74%,石英的回收率略微降至11.22%。本研究通过测定回水循环体系下离子溶出量、矿物表面的Zeta电位以及矿物表面的离子吸附量等分析手段,揭示了不同循环次数的回水中溶解离子对三种单矿物的作用机理。

湖北某中低品位胶磷矿反浮选脱镁试验研究

以湖北某中低品位高镁胶磷矿(P_(2)O_(5)品位19.37%,MgO质量分数9.90%)为研究对象,采用自制的新型反浮选脱镁捕收剂HLF,在25℃条件下进行单一反浮选试验,结果表明:在磨矿细度为-0.074 mm占70%、磷酸用量为18 kg/t、捕收剂HLF用量为1.6 kg/t的最佳条件下,得到了精矿品位为30.64%、回收率为82.05%、选矿效率为33.17%的良好浮选指标。精矿产品多元素分析和扫描电镜能谱分析结果显示,氟磷灰石与白云石实现了较好的分离。浮选优化试验结果表明,用硫酸替换磷酸作为抑制剂可达到同样的浮选效果,且能降低选矿成本。通过对比HLF和油酸钠单一反浮选脱镁指标,发现HLF相比油酸钠有更为优异的反浮选脱镁性能。研究成果可为中低品位胶磷矿的浮选研究提供借鉴。

四川某高镁低品位磷矿浮选试验研究

针对四川某高镁低品位磷矿,采用反浮选试验进行提磷降镁研究。该矿MgO品位高达9.10%,P_(2)O_(5)品位仅为18.30%,主要含磷矿物为氟磷灰石、胶磷矿,脉石矿物主要为白云石和石英,矿物间嵌布粒度细。结果表明,经过条件试验选择硫酸作为磷矿物抑制剂,硫酸粗选用量为22 kg/t,磨矿细度-0.074 mm质量分数占82.00%,捕收剂为自制羧酸类捕收剂L+H混合药剂,通过开路浮选试验确定“1粗2扫3精”浮选流程,经闭路浮选试验可使磷精矿中MgO品位降至1.07%,P_(2)O_(5)品位达到30.17%,P_(2)O_(5)回收率为78.67%,最终实现该高镁质低品位磷矿的资源化利用。

油酸根离子在氟磷灰石和白云石表面吸附动力学与吸附热力学研究

采用TOC测量以及分子模拟方法研究了油酸根离子在氟磷灰石和白云石表面的吸附动力学以及吸附热力学。吸附动力学研究结果表明,以HEDP为抑制剂时,油酸根离子在氟磷灰石和白云石表面的吸附符合准二级动力学模型,油酸根离子在氟磷灰石表面的吸附速率大于在白云石表面的吸附速率。吸附热力学研究结果表明,油酸根离子在氟磷灰石和白云石孔径内和氟磷灰石(001)面以及白云石(104)面的吸附都接近Langmuir模型。相同比表面积条件下,油酸根离子在白云石表面的吸附量高于在氟磷灰石表面的吸附量,表明单位表面积内,白云石表面比氟磷灰石表面具有更多的活性位点。

羟肟酸类药剂对氟磷灰石和白云石浮选的影响

研究了羟肟酸类药剂对氟磷灰石和白云石浮选的影响。结果表明,水杨羟肟酸对氟磷灰石和白云石有一定的选择性但回收率低;辛基异羟肟酸对两者选择性差但回收率高;苯甲羟肟酸对氟磷灰石选择性和回收率都高。通过Zeta电位测试、药剂吸附量测试和XPS图谱分析研究了苯甲羟肟酸体系下氟磷灰石和白云石的浮选机理,结果表明,苯甲羟肟酸是氟磷灰石和白云石的理想捕收剂。

分子模拟在磷矿浮选研究中的应用进展

浮选是钙镁质磷矿提质降杂的主要方法,但白云石和氟磷灰石的表面物理化学性质相似,导致难以对其高效分离。随着量子化学和计算化学的发展,分子模拟为研究钙镁质磷矿中主要矿物的晶体化学性质和界面相互作用提供了新方法,逐渐成为研究钙镁质磷矿浮选的有效工具。在梳理磷矿石浮选表面物理化学性质,特别是在润湿性、电性以及吸附特性研究的基础上,总结了分子模拟方法进展及密度泛函理论和分子动力学模拟在氟磷灰石和白云石等浮选分离中的应用,包括晶体化学性质、水分子和浮选药剂在矿物表面相互作用等,并讨论分子模拟在磷矿浮选研究中的应用前景。

Mg^(2+),Al^(3+)和Fe^(3+)对氟磷灰石表面性质的影响

矿物表面性质是影响其分散聚集和浮选行为的主要因素,通过溶液化学分析计算、浊度、接触角及Zeta-电位测试分析,研究了矿浆中,Mg^(2+),Al^(3+),Fe^(3+)等金属离子对氟磷灰石(FAP)表面性质的影响。结果表明:金属离子在溶液中的存在形式随pH值的变化而改变,FAP是亲水性矿物,添加Fe^(3+)对FAP的润湿性影响受pH的影响较大,在酸性环境中,Fe^(3+)对FAP的亲水起促进作用,在中性及碱性环境下,Fe^(3+)能较好地抑制FAP的亲水。Mg^(2+)和Al^(3+)受pH的影响较小,在中性环境下Mg^(2+),Al^(3+)离子均抑制FAP的润湿性。在pH=3~11范围内,Mg^(2+)主要以+2价的离子存在,压缩FAP表面双电层;Al^(3+)和Fe^(3+)主要是通过水解的作用生成氢氧化物沉淀覆盖在FAP表面,并且Mg^(2+),Al^(3+),Fe^(3+)均会破坏FAP的分散性,促使FAP发生聚沉现象。

溶解离子对白云石和氟磷灰石浮选及表面性质的影响研究

采用纯矿物浮选、Zeta电位和接触角测试等方法研究了溶解离子Ca^(2+)、Mg^(2+)、SO_(4)^(2-)、PO_(4)^(3-)对白云石和氟磷灰石浮选及表面性质的影响。结果表明,溶解离子会明显改变白云石和氟磷灰石的可浮性、表面电性和表面润湿性。Ca^(2+)、Mg^(2+)、SO_(4)^(2-)、PO_(4)^(3-)会降低白云石和氟磷灰石的接触角,导致其疏水性减弱,使其上浮率降低。Ca^(2+)、Mg^(2+)会使白云石和氟磷灰石表面Zeta电位升高,SO_(4)^(2-)、PO_(4)^(3-)会降低矿物Zeta电位。研究可为下一步有针对性地去除磷矿浮选中有害离子提供参考。

磨矿介质对氟磷灰石表面性质及可浮性的影响

磨矿是浮选前的准备作业,不仅为浮选提供粒度合适、解离充分的入选物料,还会对矿物表面性质产生影响,从而影响矿物的可浮性。本文通过单矿物浮选试验、扫描电镜(SEM)、原子力显微镜(AFM)和比表面积测定(BET)等方法,对陶瓷球磨和陶瓷棒磨两种形状磨矿介质的氟磷灰石颗粒形貌和可浮性进行了研究。结果表明,当使用NaOL捕收剂时,棒磨氟磷灰石的可浮性优于球磨,棒磨比球磨更有利于氟磷灰石的浮选。棒磨氟磷灰石和球磨氟磷灰石颗粒均为不规则的砾石状,颗粒棱角分明,且断口面参差不平,两种磨矿方式所得到的氟磷灰石颗粒形状系数差异不大,两者颗粒球形度(R_(o))和伸长率(EW)的分布区间差异也很微小,但棒磨氟磷灰石颗粒比球磨氟磷灰石颗粒粗糙度更大。棒磨氟磷灰石颗粒的临界表面张力小于球磨氟磷灰石,棒磨氟磷灰石颗粒疏水性更好,这一结果符合Wenzel和Cassie的表面润湿性理论,即疏水表面的润湿性随粗糙度的增大而降低。

占空比对微弧氧化生物涂层的性能影响

为研究不同占空比对微弧氧化生物涂层耐腐蚀性能的影响,以TC4合金为基体,以含有乙酸钙为主盐的溶液为电解液,采用微弧氧化技术制备含氟磷灰石的陶瓷涂层,对陶瓷涂层进行XRD、SEM、以及电化学测试。结果表明:陶瓷薄膜的相组成主要为氟磷灰石相;随着占空比逐渐增大,陶瓷薄膜的耐蚀性能出现先增大后减小的趋势,并在占空比为10%时,自腐蚀电流为1.21×10^(-7)A/cm^(2)。

双酯Gemini季铵盐在氟磷灰石与石英界面吸附行为的研究

对自制双酯Gemini季铵盐进行表面张力测试,量子化学计算,以及单矿物浮选实验,结果表明自制双酯Gemini季铵盐与十二胺盐酸盐(DDAH)相比,具有更低的CMC,更强的阳离子性,更大的分子电负性,并且在低浓度5×10^(-6)mol/L时,双酯Gemini季铵盐对石英单矿物的浮选上浮率可以达到88.89%,磷灰石上浮率仅为4.04%。通过接触角测试、分子动力学模拟,研究双酯Gemini季铵盐在石英、磷矿界面上的吸附过程,结果表明,相比磷灰石,双酯Gemini季铵盐更易于在石英表面吸附,可作为石英和氟磷灰石浮选分离的捕收剂。

载银氟磷灰石抗菌剂的制备和耐高温性能研究

以共沉淀法制备无定形纳米载银氟磷灰石粉体,将其在1000℃下进行3h的热处理后,得到载银氟磷灰石抗菌剂.通过TEM、XRD、AAS、SEM等分析测试手段对该抗菌剂进行了表征,摇瓶法抗菌实验证明该抗菌剂在经1350℃高温后仍具有100％的抗菌效果.

纳米氟磷灰石-聚醚醚酮种植体骨整合效能研究

目的:探索拥有我国自主知识产权新型纳米氟磷灰石-聚醚醚酮材料(nFA/PEEK)的生物相容性和成骨性能。方法:将通过喷砂方法制备的nFA/PEEK和聚醚醚酮(PEEK)柱状种植体各10颗,延期植入6只犬下颌前磨牙区,术后8和12周各随机处死3只,标本行X线检查,非脱钙种植骨组织切片行苦味酸品红染色、四环素荧光标记测定骨结合率(BIC)和骨矿化沉积速率(MAR)。结果:nFA/PEEK种植体周围新骨的产生和成熟均比PEEK更迅速,骨结合率更高,8和12周nFA/PEEK组的BIC分别为71.02%和85.56%,均显著高于PEEK组的10.28%和40.19%(P<0.01);nFA/PEEK组的MAR为1.77和1.49μm/d,高于PEEK组的1.29和1.13μm/d(P<0.05)。结论:nFA/PEEK与其骨床结合佳,有助于新骨生长,动物实验表明具有良好成骨效能。