改性除氟吸附剂的制备及其除氟机理的分析研究.pdf

I华中科技大学硕士学位论文摘要氟是人体必需的微量元素之一,但氟摄入过量会影响人体健康。目前国内外含氟水处理方法主要包括: 吸附法、沉淀法、电凝聚法、离子交换法、反渗透法、液膜法和共蒸馏法等,其中饮用水除氟主要以化学沉淀法、混凝沉淀法和吸附法为主。众所周知,氧化镁(MgO)是一种对氟有着较高吸附能力的吸附材料。为了克服MgO在达到最高吸氟容量时耗时过长的局限性,(在实际应用中容易流失、不易回收等局限性),本研究利用Pullulan多糖来对MgO进行改性,得到吸氟容量高、反应时间短的MgO/Pullulan(MgOP)混合物。实验证明,该混合物的去氟效果优于单独使用MgO和Pullulan多糖。本文通过一系列实验研究得到制备MgOP混合物时MgO与Pullulan最佳配比为2:3,最佳煅烧温度为450℃。利用批量平衡实验对MgO和MgOP在水溶液中的去氟效果进行的研究结果表明:MgOP可以在较短时间内达到吸附平衡,并保持较高的吸附量;当吸附达到平衡时,MgOP混合物对氟离子的吸附量达到4537mg/kg,而MgOP此时对氟离子的吸附量仅为457mg/kg;MgOP对于溶液pH的适应范围为2~12;实验还通过环境扫描电镜及能谱分析、X射线衍射及傅里叶红外光谱等方法对人工合成的MgOP混合物进行了物理化学性质的表征。将得到的平衡数据进行热力学模型和动力学模型的拟合,得出了其拟合程度较高的热力学和动力学模型分别为Langmuir等温吸附热力学模型、二级反应动力学模型以及粒子内扩散动力学模型。热力学参数ΔG0、ΔH0和ΔS0显示MgOP对氟离子的吸附作用是自发的吸热过程。总而言之,本研究合成的MgOP混合物是一种吸附效率较高,对环境适应性较好的氟吸附材料,具有良好的应用前景。关键词:MgO Pullulan MgOP混合物去氟吸附II华中科技大学硕士学位论文Abstract It has been substantiated that fluorine plays an important role in the development and maintenance healthy bones and teeth. However, excessive ingestion of fluorine could lead to fluorosis. The traditional method of removal F- from water, such as chemistry-precipitation, coagulation-precipitation, adsorption removal,RO process, ion exchange process, electrical ulation techniques, liquid- film technique, co-distillation process and so on, are applied widely around the world. Magnesia (MgO) is a well-known adsorbent showing extremely high de?uoridation capacity (DC). In order to e the limitations of MgO for field applications, an attempt has been made to modify magnesia with abundant biomaterial pure Pullulan to form magnesia/pullulan (MgOP) composite in a usable form and its merits over conventional magnesia and pure Pullulan is established. The optimal ratio 2:3 of MgO and Pullulan and the optimal calcine temperature 450℃ was obtained by a series of experiments. Removal of fluoride from aqueous solution with MgO and posite was performed with batch equilibrium experiments. results showed that MgOP can get a high DC with minimum contact time; At equilibrium, posite has a DC of 45