钙磷酸盐脱氟性能的影响因素研究

发布时间：2018-07-03 08:42

  本文选题：纳米氟磷灰石 + 无定形磷酸钙　； 参考：《南京师范大学》2012年硕士论文

【摘要】：氟是人体必需的微量元素之一,维持人体骨骼正常发育,增进骨骼和牙齿强度。如果摄入量过多会导致一类总称为“氟中毒”的疾病,长期摄入高剂量的氟更可导致骨骼变形、关节僵硬、钙化,行走困难,严重者可导致瘫痪。目前,国内外对纳米羟基磷灰石(nHAP)去除氟污染的理论研究与实际应用均较多,但是关于纳米氟磷灰石(nFAP)与无定形磷酸钙(ACP)治理氟污染鲜有报道,尤其是ACP除氟,以及施加低分子量有机酸对ACP的除氟效果影响还未见报。因此本文主要研究nFAP与ACP的除氟效果,以及施加低分子量有机酸对ACP的除氟影响。 论文分四个部分： (1)沉淀法制备纳米氟磷灰石(nFAP)及无定形磷酸钙(ACP)的研究 通过X射线衍射(XRD)、红外光谱(IR)和透射电镜(TEM)对其形貌、晶型结构等方面的性能进行了表征。结果表明沉淀法制备的nFAP均为颗粒均匀、纯相态的物质。 (2)纳米氟磷灰石的除氟实验 本实验通过考察三种材料(nFAP, nFHAP, nHAP)用量、F-溶液浓度、溶液pH、搅拌时间、温度、再生条件,对比三种材料除氟效果。并且运用Freundlich和Langmuir等温吸附方程及一级动力学和二级动力学方程进行拟合,此外还计算了热力学函数AG°、△S°、ΔH°,并初步探讨了可能的吸附机理。实验结果表明,nFAP与nHAP的除氟机理主要为氢键吸附,nFAP与nHAP的除氟效果相当,nFAP的再生能力强于nHAP,所以nFAP可以用于含氟废水的处理。 (3)ACP的除氟实验 本实验通过考察三种材料(ACP, ACP-nHAP, nHAP)用量、F-溶液浓度、溶液pH、搅拌时间、温度条件,对比三种材料的除氟效果。实验结果表明,在pH5或是温度高于30℃,ACP的除氟效果明显好于nHAP,但是pH5时,其吸附效果不如nHAP。得出结论：当材料的粒径越小,除氟效果越好,但是当粒径达到无定形状态,其除氟效果受条件影响,当温度较高或是pH较低,无定形状态的除氟效果优于纳米级羟基磷灰石。 (4)施加低分子量有机酸对ACP除氟能力的影响 本实验选择了草酸、柠檬酸苹果酸作为低分子量有机酸(LMWOAs)的代表。考察在不同ACP加入量、溶液pH值、氟初始浓度、反应时间、反应温度等条件下,LMWOAs对ACP除氟能力的影响。得到结论三种有机酸均促进ACP的除氟能力,其增强程度为柠檬酸草酸苹果酸。
[Abstract]:Fluorine is one of the essential trace elements to maintain the normal development of human skeleton and enhance the strength of bone and teeth. If too much intake leads to a class of diseases known as fluorosis, long-term intake of high doses of fluoride can lead to bone deformation, joint stiffness, calcification, difficulty in walking, and severe paralysis. At present, there are many theoretical studies and practical applications of nano-hydroxyapatite (nHAP) in fluoride removal at home and abroad. However, there are few reports on the treatment of fluoride pollution by nano-fluoropatite (nFAP) and amorphous calcium phosphate (ACP), especially on the removal of fluoride by ACP. The effect of low molecular weight organic acid on the defluorination of ACP has not been reported. Therefore, the defluorination effect of nFAP and ACP and the effect of low molecular weight organic acid on the defluorination of ACP were studied in this paper. The thesis is divided into four parts: (1) Nano-fluoroapatite (nFAP) and amorphous calcium phosphate (ACP) were prepared by precipitation method. The morphologies of nano-fluorapatite (nFAP) and amorphous calcium phosphate (ACP) were investigated by X-ray diffraction (XRD), infrared spectroscopy (IR) and transmission electron microscopy (TEM). The properties of crystal structure were characterized. The results show that the nFAP prepared by precipitation method is homogeneous in particle size and in pure phase. (2) the experiment of fluorination of nano-fluorapatite was carried out. The concentration of F- solution, pH of solution, stirring time of three kinds of materials (nFAP, nFHAP-, nHAP) were investigated. Temperature, regeneration condition, contrast three kinds of material to remove fluorine effect. Freundlich and Langmuir isothermal adsorption equations and first-order and second-order kinetic equations were used to fit the equation. In addition, the thermodynamic functions AG 掳, S 掳, 螖 H 掳were calculated, and the possible adsorption mechanism was preliminarily discussed. The experimental results show that the mechanism of defluorination between nFAP and nHAP is that the hydrogen bond adsorption of nFAP and nHAP is equivalent to the regeneration ability of nFAP than nHAP.Therefore, nFAP can be used in the treatment of fluorine-containing wastewater. (3) the defluorination experiment of ACP is carried out. The concentration of F- solution in three kinds of materials (ACP, ACP-nHAP, nHAP) was investigated. The pH of the solution, stirring time, temperature conditions, the comparison of the three materials of fluoride removal effect. The experimental results show that the defluorination effect of ACP at pH 5 or above 30 鈩，

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