【作者】 孙榕；

【导师】 魏正贵；

【作者基本信息】 南京农业大学 ， 土壤学， 2009， 硕士

【摘要】 磷灰石是分布极广的钙磷酸盐矿物,同时也是脊椎动物的骨、牙等硬组织的主要无机组分。由于具有特殊的晶体化学特点,天然磷灰石可以作为一种环境功能矿物材料用于处理含重金属和氟的废水。而人工合成的纳米羟基磷灰石(n-HAp)粉体具有较高的表面活性和良好的吸附性能,作为一种新型的、环境友好和高效的吸附剂,被广泛地应用于生物蛋白质的吸附与分离、色谱柱、基因和药物载体、含重金属污染土壤和废水的吸附分离等领域。明胶化学成分与胶原相似、具有良好的物理化学性质,供应充足、价格便宜。很多学者利用明胶代替胶原来合成仿生骨。明胶作为一种蛋白质,含有大量的羟基,羰基,亚胺基等官能团,明胶与羟基磷灰石(HAp)复合可以有效地增强HAp与聚合物界面的化学键。从而,可以大大改善HAp的表面性质。磷灰石是骨骼的主要无机成分。骨骼中的磷灰石结晶程度差,并且以碳磷灰石形态存在,导致它比磷矿石中的磷灰石更易溶解。因此有人建议可以将骨粉作为一种潜在的合适的磷源用来固定重金属。而且作为一种修复材料它的溶解性很好、利用率高、价格便宜。但将这几种材料应用于吸附分离有机物的研究还罕见报道。本文试图将n-HAp用于吸附分离水中草酸,消除反相液相色谱测定过程中硝酸的干扰；将n-HAp及其复合材料用于吸附水中硝基苯,对其去除硝基苯性能进行研究,分析其对硝基苯的吸附规律。具体研究内容及结果如下：(1)以廉价的配合物前躯体热分解法制备了n-HAp,利用X射线衍射(XRD)和红外光谱(IR)对其结构进行了表征。结果表明,该方法制备的n-HAp为纯相态物质、粒度均匀。(2)将n-HAp用于吸附分离草酸和硝酸。结果表明,硝酸根离子对RP-HPLC测定草酸的干扰可以通过n-HAp固相萃取而消除。草酸在初始pH 2.5,反应时间60min条件下被n-HAp完全吸附。然后用0.1mol/L(NH4)2HPO4溶液将吸附在n-HAp表面的草酸洗脱下来。草酸的回收率94.8%—99.3%。同时,通过分析FT-IR和XRD的试验结果,n-HAp吸附草酸的机理也得到证实,草酸根与钙离子生成沉淀,从而达到吸附草酸的目的。(3)采用共沉淀法合成HAp-GEL复合物。利用X射线衍射(XRD)、透射电镜(TEM)和红外光谱(IR)对其结构进行了表征。(4)将n-HAp、HAp-GEL复合物、骨粉应用于吸附硝基苯。结果表明：硝基苯的吸附速率很快。吸附等温线可以用Langmuir和Freundlich方程很好地表现,但Freundlich方程更适合。硝基苯的吸附量随着温度升高、pH增加、离子强度提高、Pb的浓度的增加,或者腐殖酸的浓度的增加而降低。另外,有机溶剂甲醇和丙酮存在也导致硝基苯吸附的降低。以甲醇为洗脱剂可以很好地回收三种吸附剂。热力学参数显示硝基苯的吸附过程是一个自发的、放热的物理过程。吸附过程可能主要因为疏水作用。(5)三种材料吸附硝基苯的能力依次为：HAp-GEL>骨粉>n-HAp.更多还原

【Abstract】 Apatite is the most widespread calcium phosphate mineral, and is also the main inorganic component of vertebrate bones, teeth and other hard tissue. Due to the particular crystal-chemical characteristics, mineral apatites can be used as excellent environmental function materials for the treatment of heavy-metal and F-in wastewater. However, the synthetic nano-hydroxyapatite (n-HAp) possesses excellent surface activity and high adsorption ability. As a new and environment friendly adsorbent, n-HAp has been widely used as carriers for drugs and genes, adsorbents for chromatography to separate proteins, and removal of heavy metal ions to recover the contaminated soils, wastewater, etc.Gelatin and collagen are both in very similar chemical composition. Gelatin shows well-defined physical and chemical properties, and it is adequate supply and very cheap, many researchers have used gelatin instead of collagen to synthesize biomimetic bone. Gelatin as a protein, containing a large number of hydroxyl, carbonyl, imino functional groups, such as, HAp/gelatin composite can be effectively enhanced HAp interface chemical bond with the polymer. Thus, it can greatly improve the surface properties of HAp.A form of apatite is the principal mineral constituent of bone. Apatite in bone is poorly crystalline and carbonated and its carbonate content makes it more soluble than rock apatite. It suggested that bone meal might prove to be a potentially suitable source of phosphate for metal fixation due to its intermediate solubility; it would also provide a cost-effective remediation material. But studies of the adsorption of organic pollution in water by these material rarely reported.This paper attempts to use solid-phase extraction with n-HAp for solving interference from nitrate ions on oxalic acid in reversed-phase high performance liquid chromatography (RP-HPLC); use n-HAp and its composites to removal of nitrobenzene from aqueous solution. Specific studies are as follows: (1) Nano-sized HAp was synthesized by the thermal decomposition of complex precursors. XRD, IR were used to characterize the n-HAp. Results showed that the smples were pure HAp. The n-HAp was sphere-like and weakly aggregated.(2) The interference from nitrate ions on oxalic acid in RP-HPLC is avoided by solid-phase extraction with nanosized hydroxyapatite. Nitrate ions are eliminated as they cannot be adsorbed by hydroxyapatite, by contrast, oxalic acid can be adsorbed completely within 60 minutes at initial pH 2.5, and then the oxalic acid retained is eluted from nanosized hydroxyapatite with 0.1 mol/L (NH4)2HPO4. Recoveries for oxalic acid are from 94.8%to 99.3%. Meanwhile, the adsorption mechanism of oxalic acid on nanosized hydroxyapatite is proved to be the coordination between oxalate and calcium, by the results of FT-IR and XRD analyses.(3) The HAp-GEL composite was prepared by precipitation method. XRD, TEM, IR were used to characterize the HAp-GEL composite.(4) The potential of the application of n-HAp, HAp-GEL composite, bone meal as adsorbents to remove nitrobenzene from waters was evaluated. Results show that nitrobenzene adsorption was found to be rapid. The adsorption isotherms were well described by the Langmuir and the Freundlich models, but the latter being found to provide the better fit with the experimental data. All parameters that might influence the adsorption process were assessed:the amount of nitrobenzene adsorbed decreased with an increase of pH, temperature, ionic strength, lead, or HA. The desorption process showed a reversibility of nitrobenzene adsorption onto adsorbents. The presence of organic solvent, resulted in a decrease in nitrobenzene adsorption. The recovering experiment indicates that the spent adsorbents could be satisfactorily regenerated by solvent regeneration. The thermodynamic parameters suggests that the adsorption of nitrobenzene onto adsorbents was physisorption, spontaneous and exothermic in nature. Therefore, the adsorption might be primarily brought about by hydrophobic interaction between nitrobenzene and adsorbents surface.(5) Adsorption capacity of nitrobenzene on the three materials followed by: HAp-GEL> bone meal> n-HAp.更多还原