改性硅藻土吸附废水中铅镉的研究

发布时间：2019-03-01 18:24

【摘要】：利用CaCO3、MnO2和Mg(OH)2对硅藻土进行改性,可以提高其吸附性能。本文研究了这三种改性硅藻土分别对铅镉离子的吸附性能；分析了吸附这两种离子的吸附等温线模型、吸附热力学和吸附动力学模型,得到以下结论：1.对改性材料表征的分析结果表明,改性后硅藻土表面包裹着改性物质,分布的不是很均匀,同时发现不少孔隙中也有改性物质。改性物颗粒与硅藻土之间形成较多的微孔,其比表面积增大,有利于吸附：改性后,改性物的特征吸收峰出现了；经过改性后,二氧化硅衍射峰有所降低,出现了改性物晶体结构的特征衍射峰,说明改性成功。2. CaCO3、MnO2和Mg(OH)2改性硅藻土对铅镉离子的吸附性能。去除率和吸附量均随pH的增大而增加,当pH=5时,pb2+的去除率分别为95.51%、92.15%和95.56%,吸附量分别为99.33mg/g、95.84mg/g和99.38mg/g。当pH=6时,Cd2+的去除率分别为78.56%、75.48%和80.05%,吸附量分别为81.70mg/g、78.50mg/g和83.25mg/g。去除率随初始浓度的增加而减小,吸附量却是增加的。当初始浓度为500mg/L时,对pb2+去除率分别为43.25%、39.17%和45.18%,吸附量分别为216.25mg/g、195.85mg/g和225.90mg/g。对Cd2+的去除率分别为36.12%、35.78%和38.92%,吸附量分别为180.60mg/g、178.90mg/g和194.60mg/g。去除率随着投加量的增加而增加,吸附量却是减小的。当投加量为1g/L时,对pb2+的去除率分别为99.14%、97.22%和99.72%。吸附量分别为99.14mg/g、97.22mg/g和99.72mg/g。对Cd2+的去除率分别为85.72%、82.48%和88.64%。吸附量分别为85.72mg/g、82.48mg/g和88.64mg/g。3. Langmuir模型符合改性硅藻土对铅镉离子的等温吸附。吸附过程是吸热反应、是自发进行的、吸附过程中混乱度增加,高温和低浓度有利于吸附,吸附均为物理吸附。改性硅藻土吸附铅镉离子达到平衡吸附的时间分别为60min和90min,吸附动力学符合伪二阶动力学模型。
[Abstract]:When diatomite was modified by CaCO3,MnO2 and Mg (OH)-2, the adsorption performance of diatomite could be improved. In this paper, the adsorption properties of these three modified diatomite for lead and cadmium ions were studied, and the adsorption isotherm model, adsorption thermodynamics and adsorption kinetics model of these two ions were analyzed, and the following conclusions were obtained: 1. The results of characterization of modified material show that the modified diatomite surface is coated with modified material, and the distribution is not very uniform. At the same time, it is found that there are also many modified substances in the pores of the modified diatomite. There are many micropores between the modified particles and diatomite, and their specific surface area increases, which is beneficial to adsorption. After modification, the characteristic absorption peak of the modified material appears. After modification, the diffraction peak of silica decreases, and the characteristic diffraction peak of the crystal structure of the modified material appears, which shows that the modification is successful. 2. Adsorption of lead and cadmium ions on diatomite modified by CaCO3,MnO2 and Mg (OH) 2. When pH=5 was used, the removal rate of pb2 was 95.51%, 92.15% and 95.56% respectively, and the adsorption capacity was 99.33 mg / g, 95.84 mg / g and 99.38 mg / g / g, respectively. The removal rate and adsorption amount of pb2 were increased with the increase of pH, the removal rate of pb2 was 95.51%, 92.15% and 95.56%, respectively. When pH=6 was used, the removal rate of Cd2 was 78.56%, 75.48% and 80.05%, respectively. The adsorption capacity was 81.70 mg / g, 78.50 mg / g and 83.25 mg / g respectively. The removal rate decreases with the increase of initial concentration, but the adsorption capacity increases. When the initial concentration of 500mg/L was 500mg/L, the removal rate of pb2 was 43.25%, 39.17% and 45.18% respectively, and the adsorption capacity was 216.25 mg / g, 195.85 mg / g and 225.90 mg / g respectively. The removal rate of Cd2 was 36.12%, 35.78% and 38.92%, respectively. The adsorption capacity was 180.60mg / g, 178.90mg / g and 194.60mg / g respectively. The removal rate increases with the increase of the dosage, but the adsorption capacity decreases. The removal rate of pb2 was 99.14%, 97.22% and 99.72% when the dosage of 1g/L was 99.14%, 97.22% and 99.72%, respectively. The adsorption capacity was 99.14 mg / g, 97.22 mg / g and 99.72 mg / g respectively. The removal rates of Cd2 were 85.72%, 82.48% and 88.64% respectively. The adsorption capacity was 85.72 mg / g, 82.48 mg / g and 88.64 mg / g / 3, respectively. The Langmuir model is consistent with the isothermal adsorption of Pb and CD ions by modified diatomite. The adsorption process is endothermic and spontaneous. The degree of confusion increases during the adsorption process. High temperature and low concentration are favorable to adsorption. The adsorption is physical adsorption. The equilibrium adsorption time of Pb and CD ions on modified diatomite was 60min and 90 min, respectively. The adsorption kinetics of the modified diatomite obeyed the pseudo-second-order kinetic model.
【学位授予单位】：昆明理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：X703

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