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摘要脱硫石膏（FGD）是一种燃煤电厂常见的固体废弃物，由于产生量巨大，现已成为燃煤电厂继粉煤灰之后的第二大固废。研究通过水热合成的方法，将脱硫石膏转化为羟基磷灰石（FGD-HAP），并考察其对废水中Pb2+、Cd2+的去除能力。以静态实验为基础，分别改变废水pH值、吸附反应时间以及废水重金属初始浓度等条件，系统研究FGD、FGD-HAP的吸附性能。实验结果表明，两种吸附剂对重金属离子的吸附过程均受废水pH影响，且随pH升高吸附能力随之升高，其最佳pH范围为5.0-6.0。此外，为充分研究吸附剂对两种重金属离子的吸附机理，研究引入经典的动力学与等温线模型对实验数据进行拟合。拟合结果显示，吸附动力学数据均符合伪二级动力学模型，表明脱硫石膏与羟基磷灰石对重金属的吸附过程为化学吸附控制步骤。从Langmuir等温线公式计算得FGD对Pb2+和Cd2+的最大吸附量分别为161.3 mg/g和32.57 mg/g，而FGD-HAP对Pb2+和Cd2+的最大吸附量分别为277.8 mg/g和43.10 mg/g，表明脱硫石膏羟基磷灰石对Pb2+和Cd2+的吸附效果更好。从热力学参数计算结果可以看出，两种吸附剂对重金属离子的吸附均为自发的吸热的过程，且不论FGD还是FGD-HAP，对Pb2+的热力学参数高于Cd2+，表明其与Pb2+有较高的亲和力。研究充分表明脱硫石膏与脱硫石膏羟基磷灰石作为吸附剂在重金属离子Pb2+和Cd2+废水治理中具有良好的应用前景。31363
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关键词 脱硫石膏 羟基磷灰石 吸附 铅离子 镉离子
毕业论文设计说明书外文摘要
Title Conversion of waste FGD gypsum into hydroxyapatite for removal of Pb2+ and Cd2+ from wastewater
Abstract
Flue gas desulfurization (FGD) gypsum, a common solid waste which is generated from coal-fired power plants. Due to the huge generation, it has become the second largest solid waste in plants. In this study, it was successfully transformed to hydroxyapatite (FGD-HAP) by hydrothermal method. It was examined as adsorbent for removal of Pb2+ and Cd2+ from wastewater. Batch experiments were carried out by changing the pH values, contact time and initial metal concentration. The result of pH influence indicated that the adsorption of two ions was pH dependent process, the adsorption amount of two metals go up obviously with the increasing of pH, and the pH 5.0–6.0 was found to be the optimum condition. Besides, in order to study the adsorption mechanism, the achieved experimental data were analyzed by different kinetic and isotherm models. The kinetic studies displayed that the pseudo-second order kinetic model could describe two adsorption processes well with high correlation coefficient, and the Langmuir isotherm model provided the best fit to the equilibrium experimental data. The maximum adsorptions capacities of FGD-HAP calculated from Langmuir equation were 277.8 and 43.10 mg/g for Pb2+ and Cd2+, respectively. As for the FGD gypsum, the maximum adsorption capacities were 161.3 and 32.57mg/g, respectively. The thermodynamic parameters revealed the adsorption processes of both adsorbents were endothermic and spontaneous in nature. The thermodynamic parameters of Pb2+ were all higher than Cd2+, demonstrating the stronger affinity between adsorbents and Pb2+. From this study, we can confirm that both the FGD-HAP and FGD were promising alternative adsorbents in treatment of toxic Pb2+ and Cd2+ wastewater.
Keywords (FGD-HAP) Adsorption Desorption Pb2+ Cd2+
目次
1 绪论 1
1.1中国水资源现状 1
1.2中国水资源的污染 2
1.3中国水资源重金属的污染 3
1.4重金属污染对人体的危害 3
1.5水体重金属污染的治理手段 4
2 材料与方法 6
2.1 材料 6
2.2 FGD-HAP的合成及表征 6
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