沉淀法制备碳酸羟基磷灰石的影响因素

通过沉淀法制各了高碳酸根(CO32-)含量的纳米碳酸羟基磷灰石(nanosized carbonated hydroxyapatite,CHA).研究了合成温度、初始原料碳酸氢钠(NaHCO3)和磷酸氢二铵[(NH4)2HPO4]的摩尔比[n(CO32-)/n(PO43-)]和pH值对CO32-替代的影响.用X射线衍射和透射电镜表征CHA粉体的物相组成和形貌.用碳硫元素分析仪和红外光谱研究了CO32-替代的含量和类型.结果表明:随着合成温度的升高或原料中CO32-浓度的减小,CHA晶粒尺寸和长径比增加;合成CHA中的晶相组成和CO32-含量主要由n(CO32-)/n(PO43-)决定;而CO32-的替代类型则主要取决于n(CO32-)/n(PO43-)和pH值.在高pH值或高n(CO32-)/n(PO43-)的合成条件下,能够获得以B型替代为主的CHA.     

碳酸化对白云石热分解产物联合除磷除氟的影响

本文主要研究一种新型吸附剂的制备,及其对磷、氟废水的联合处理。以白云石为原材料,经煅烧和碳酸化处理后,通过XRD、XRF、SEM、FTIR等对其产物组成、形貌等进行表征,同时探究了反应时间、初始磷和氟浓度、固液比、pH值等环境参数对联合除磷除氟的影响。结果表明:随着固液比增大,剩余氟离子浓度逐渐降低后趋于稳定;动力学结果表明氟离子的去除更加符合准二级动力学方程(R²>0.967);溶液初始pH值对实验结果影响不显著;Langmuir等温吸附模型可以更好地描述氟离子去除过程。煅烧-碳酸化白云石(CCD)联合除磷除氟的机理为:CCD与溶液中的磷发生反应,生成羟基磷灰石,然后OH^-被F^-取代,转化生成氟磷灰石;同时CCD溶出的Ca²⁺、Mg²⁺也与F^-反应生成相应的沉淀。     

新型除氟载铁(Fe~(3+))聚丙烯酰胺凝胶的性能研究

以Fe3+溶液在30℃,pH=1.75条件下对聚丙烯酰胺凝胶改性2 h,得到载铁凝胶。运用载铁凝胶进行除氟实验,考察pH值、反应温度、反应时间、初始F-浓度以及干扰离子等因素对载铁凝胶的除氟效果的影响。结果表明,载铁聚丙烯酰胺凝胶适于氟离子浓度为5 mg/L的含氟溶液在30℃,pH=8条件下反应2 h,除氟率可达69.32%。Na2SO4、Na2CO3、CaCl2和KCl等干扰离子对除氟效果的影响较大,而且干扰离子含量越多影响越大,除氟率越低,故用凝胶进行除氟时应先除去干扰离子。     

氟羟基磷灰石烧结体的热物性和抗折强度研究

以湿化学法制备了不同氟替代量的氟羟基磷灰石(FHA,Ca10(PO4)6(OH)2-2xF2x,0相似文献   

水化氯铝酸钙去除水中氟及其动力学研究

采用聚合氯化铝和电石渣合成水化氯铝酸钙,用于处理低浓度的含氟水。探讨了吸附时间、溶液初始pH值、吸附剂加入量、初始氟离子浓度及竞争阴离子等因素对氟离子吸附效果的影响。研究表明,100 mL初始氟离子浓度为27.25 mg/L的溶液中加入水化氯铝酸钙1.5 g/L、pH=3,在常温条件下水浴振荡(160 r/min)吸附90 min,其处理后浓度可满足国家《无机化学工业污染物排放标准》(GB 31573—2015)6 mg/L的直接排放标准。水化氯铝酸钙对氟的吸附过程符合准二级动力学模型,并且颗粒内扩散模型表明,水化氯铝酸钙吸附氟离子是一个以化学吸附为主的复杂过程。     

陕南地区绿茶中氟离子含量的测定

为了解陕南地区绿茶中氟含量,采用氟离子选择电极法对陕南地区所产的5种代表性绿茶中的氟含量进行了测定。考察了浸提温度、茶水比、浸提时间、冲泡次数对茶叶中氟浸出率及茶汤中氟浓度的影响情况。结果表明茶叶中氟的浸出率随浸提温度的升高而升高,随茶水比增加而降低,茶汤中氟浓度随茶水比增加而增加;随冲泡次数增加,茶叶中氟的浸出率变化不大,茶汤中氟浓度降低。所调查的陕南地区5种绿茶中的氟含量在46.9~49.6mg.kg-1之间,低于绿茶平均氟含量,可作为一种安全的氟来源。     

氟和碳酸根复合掺杂制备磷灰石

通过共沉淀法制备碳酸根和氟复合掺杂纳米羟基磷灰石(CFHA)。利用X射线衍射、透射电子显微镜和红外光谱测试等方法研究了反应体系中Na~+掺杂、碱液的添加时机、原料的钙源/磷源配比和掺杂离子浓度对CFHA结构和形貌的影响。结果表明:反应体系中Na~+存在有利于晶体生长和减小晶格畸变;氟替代对形貌影响不大,而随着碳酸根浓度增加,晶体尺寸和长径比减少。Na~+以及高F~-和CO_3~(2-)浓度均利于碳酸根的B型替代。后添加碱液方式得到磷灰石碳酸根替代量较少,晶体呈片状形貌;而反应前添加碱液促进了晶体的团聚现象。控制原料中的钙源/磷源配比可获得利于碳酸根掺杂的纯磷灰石。     

污水处理厂测氟方法的选择探讨

通过氟离子选择电极与氟试剂法对比,得出氟离子选择电极法不适合测定经铝、铁混凝剂处理后的废水中氟离子浓度的结论。氟离子选择电极法测得的结果比氟试剂法测得的值高,且随着废水氟离子浓度增加,误差增大。     

超声化学法合成SrTiO3纳米颗粒形貌的演变

以TiCl4和SrCl2·6H2O为原料,采用超声化学法在较低温度下合成了结晶度良好的星形、方形和球形SrTiO3纳米粉体.实验研究了初始反应物离子浓度、超声时间、pH值对合成产物形貌的影响.用X射线衍射仪、扫描电镜和和能谱仪测定粉体的组分和形貌.结果表明:改变超声时间、pH值和初始反应物离子浓度可以控制SrTiO3纳米颗粒形貌的演变.控制反应时间为40～80min,pH值为12和13时,初始反应物离子浓度低时得到四角对称的星形SrTiO3纳米颗粒,离子浓度增加得到方形和球形颗粒;pH值为14时得到方形和球形的SrTiO3纳米颗粒.     

改性骨炭去除饮用水中氟离子的研究

文章旨在研究改性骨炭对饮用水中氟离子的去除效果。用AlCl3对常见的骨炭进行改性,并考察了pH、氟溶液初始浓度、温度及吸附剂用量对氟离子吸附去除的影响。结果表明:经AlCl3溶液改性的骨炭,用量为0.2 g/L时,其在24 h内对10 mg/L氟离子的去除率达97%以上。该吸附剂比未改性效果好,具有一定的应用前景。     

Sol–Gel Preparation and Properties of Fluoride-Substituted Hydroxyapatite Powders

Hydroxyapatite (HA) and fluor-hydroxyapatite (FHA) powders were synthesized by a sol–gel method for usage as bone filler and drug carrier. Calcium nitrate and triethyl phosphite were used as precursors under an ethanol–water-based solution. Different amounts of ammonium fluoride (NH₄F) were incorporated for the preparation of FHA powders. With heat treatment above 400°C, a characteristic apatite phase was observed for all the sol–gel powders. However, the crystallization temperature decreased with increasing fluoride addition. The tricalcium phosphate (TCP) phase formed in the pure HA powder above 800°C was attenuated in the FHA powders, confirming an enhanced phase stability of the FHA powders. Increasing the F⁻ addition improved crystallinity and increased the crystallite size, as was determined from X-ray diffraction (XRD) analyses. The lattice parameters of the heat-treated powders varied corresponding to the fluoride addition, i.e., a gradual decrease in the a -axis, while little change in the c -axis was observed with increasing fluoride addition, indicating a nearly complete substitution of fluoride within the apatite lattice. However, little difference was observed with heat-treatment temperatures (400°–1000°C). The powders substituted with fluoride exhibited reduced dissolution rates in an in vitro solution as compared with the pure HA powder, suggesting the possibility of tailoring bioactivity with fluoride substitution.     

Conversion of HA on NT-C/C Composites from Ultrasonic Induction Heating Deposited Monetite to FHA Coating by an Alkaline Followed by NaF Solution Hydrothermal Treatment Methods

An ultrasonic induction heating (UIH) deposited monetite coating on (NH₄)₂S₂O₈ treated (NT) C/C composites was subjected to a hydrothermal treatment to form a hydroxyapatite (HA) coating. This HA coating was then placed in a NaF solution and hydrothermally treated a second time to produce a fluorinated hydroxyapatite (FHA) coating. The structure, morphology and chemical composition of the HA and FHA coatings were characterized by XRD, FTIR, XPS SEM and EDS, and the adhesiveness of the two coatings to the NT-C/C substrates was evaluated by a scratch test. The results showed that after the NaF treatment, the FHA coating was a mixture of FHA and HA with some calcium oxides, and the FHA showed a higher degree of crystallization than the HA coating though the morphologies were similar. In addition, the EDS-determined Ca/P atomic ratio for the FHA coating was about 1.78 which was larger than 1.69 ratio of the HA coating. The bonding strength of the HA coating on C/C could reach a critical load of 60.3 N, while that of the as-prepared F-containing HA coating only had a critical load of 42.4 N. The reason of the lower adhesion for the FHA coating than that for the HA coating is suggested to be correlated with the constituent and structure of the two coatings.     

含氟羟基磷灰石生物陶瓷的制备及其研究

采用固相反应热烧结法制备不同氟含量的含氟羟基磷灰石(FHA)生物陶瓷.探讨氟对生物陶瓷微结构和致密化行为的影响.利用X射线衍射仪(XRD)分析生物陶瓷相结构;利用扫描电镜(SEM)分析陶瓷的断面形貌及气孔率.结果表明:采用固相反应热烧结法成功制备了含氟羟基磷灰石生物陶瓷;随着氟含量的增加,5种不同成分陶瓷的致密度呈现先下降后上升的趋势,氟的引入使得生物陶瓷的真密度增加,结构稳定性提高.     

电沉积含氟羟基磷灰石/纳米二氧化钛复合涂层的表征与性能研究

根据含氟羟基磷灰石(FHA)陶电沉积瓷技术,将纳米二氧化钛微粒加入电解液中,在钛基体表面进行电化学复合共沉积,获得了含氟羟基磷灰石复合纳米TiO2涂层(FHA/n-TiO2).对FHA/n-TiO2纳米复合涂层进行了真空烧结处理,并通过X射线衍射(XRD)、扫描电镜(SEM)、红外光谱(IR)、X射线光电子能谱(XPS...     

4-氟苯甲醛的合成工艺研究

以4-氯苯甲醛（PCAD）和无水氟化钾为原料,采用卤素交换氟化反应,反应蒸馏技术一步合成4-氟苯甲醛（PFAD）。考察了溶剂、催化剂、投料比对反应的影响,得出最佳工艺条件为以1,3-二甲基丙撑脲为溶剂,四苯基二氟化氢膦盐（Ph4PHF2）为催化剂,n（KF）：n（PCAD）：n（Ph4PHF2）=3：1：0.1。在此条件下,反应与蒸馏同时进行,4-氟苯甲醛的收率可达90.6%。     

Surfactant-free electrochemical synthesis of fluoridated hydroxyapatite nanorods for biomedical applications

Fluoridated hydroxyapatite (FHA) [Ca₁₀(PO₄)₆F_x(OH)_2−x, x = 0–2] is believed to be a promising calcium phosphate (CaP) to replace pure hydroxyapatite (HA) for next-generation implants, owing to its better biocompatibility, higher antibacterial activity, and lower solubility. Notably, the shape and size of the CaP crystals play key roles in their performance and can influence their applications. One-dimensional (1D) FHA nanorods are important CaP materials which have been widely used in regenerative medicine applications such as restorative dentistry. Unfortunately, the traditional synthesis methods for FHA nanorods either employ surfactants or take a relatively long time. In this study, we aimed to propose a facile synthesis route to fabricate FHA nanorods without any surfactants using an electrochemical deposition method for the first time. This study focused on preparing FHA nanorods without the assistance of any surfactant, unlike the traditional synthesis methods, to avoid chemical impurities. FHA nanorods with lengths of 124–2606 nm, diameters of 28–211 nm, and aspect ratios of 4.4–21.8 were synthesized using the electrochemical method, followed by a heat treatment. For the as-synthesized FHA nanorods, the Ca/P ratio was 1.60 and the atomic concentration of F was 2.06 at.%. An ultrastructure examination revealed that each FHA nanorod possessed long-range order, good crystallinity, and a defect-free lattice with a certain crystallographic plane orientation along the whole rod. In short, we propose a novel, surfactant-free, cost-saving, and more efficient route to synthesize FHA nanorods which can be widely applied in multiple biomedical applications, including drug delivery, bone repair, and restorative dentistry.     

模板剂对共沉淀法合成纳米羟基磷灰石粉体形貌的影响

采用共沉淀法,以Ca(NO3)2.4H2O和(NH4)2HPO4为反应体系,分别添加硫酸软骨素、琼脂糖和天门冬氨酸作为模板剂,引入生物矿化作用,合成了不同形貌的纳米羟基磷灰石粉体。采用X射线衍射法和透射电子显微镜分析了合成产物的晶相结构和粉体形貌。结果表明3种模板剂作用下合成的样品都是纯相的纳米羟基磷灰石。在添加硫酸软骨素(≥0.2%,质量分数,下同)或琼脂糖(1.0%)的条件下,当反应体系钙磷比(钙与磷的摩尔比)为1.67,反应pH值为11.0,纳米羟基磷灰石的形貌分别是梭形短片状和纤维丝状。当天门冬氨酸浓度为2.0%时,若反应体系钙磷比为1.62,反应pH值为10.0,其形貌为类球状;若反应体系钙磷比为1.72,反应pH值为8.5,其形貌则为片状。     

Growth of TiO2-based nanotubes on Ti–6Al–4V alloy

The possibility of tailoring titania nanotube films on Ti–6Al–4V alloy is investigated using electrolytes based on NH₄H₂PO₄ with the addition of different concentrations of NH₄F. Several morphologies from high aspect ratio nanotubes to barrier layers are achieved by the control of the electrolyte composition, regarding its pH and fluoride concentrations. The morphology and composition of the anodic layers were evaluated by scanning and transmission electron microscopy, Rutherford backscattering spectroscopy (RBS) and Wavelength dispersive X-ray fluorescence spectroscopy.The formation efficiency and the fluoride ions content in the nanotubes depend on the F concentration in the electrolyte. The higher concentration of fluoride ions in the electrolyte promotes an increase of the F incorporated in the nanotubes, about 12 at.% but, reduces the nanotube formation efficiency. However, no significant presence of phosphorus was detected into the films by means of the above-mentioned analytical techniques.