铁铜镧复合氧化物吸附水中砷的实验研究

发布时间：2018-07-02 15:47

  本文选题：铁铜镧复合氧化物 + 砷　； 参考：《哈尔滨工业大学》2017年硕士论文

【摘要】：砷较大的毒性使得水源砷污染问题受到了许多国家的关注。我国在2006年将饮用水砷浓度调整为10μg/L,更加严格的标准也进一步促进了除砷工艺研究的深入。在除砷技术中,吸附法由于经济有效的特点而受到大量研究,而吸附剂作为吸附法的核心,如何开发一种能高效除砷的吸附剂是当前的研究热点。本研究旨在结合磁性铁氧化物的磁分离性能、铜氧化物适用范围大以及镧氧化物对砷吸附能力强的优点,制备出能结合三者优点的铁铜镧复合氧化物,并对其吸附砷的性能进行研究考察。采用化学共沉淀法制备出一系列铁铜镧复合氧化物吸附剂,对比了各吸附剂对水中As(V)和As(III)的吸附效果,确定了铁铜镧比例为2:1:4,陈化温度50℃,干燥温度80℃为最佳制备条件。铁铜镧复合氧化物是由纳米级的球状、片状及棒状颗粒物团聚而成,吸附剂表面不均匀,为多孔状不规则结构,材料主体结构可能为反立方尖晶石型,同时材料中可能含有Fe3O4、Fe Cu2O4、La(OH)3以及Cu O。该材料的BET表面积为27.89m2/g,平均孔径为32.295 nm(4V/S)。材料的等电点为7.2,当溶液p H7.2时,材料表面显正电性。通过磁滞回线确定了材料的矫顽力为50.109 emu/g,通过永磁体能将该材料从水中快速分离出来。Langmuir模型对As(V)和As(III)吸附过程的拟合效果最好,其相关系数R2均都达到了0.97以上,并且在这15、25、35℃温度下对于As(V)的饱和吸附量分别达到了116.59、138.26、155.58 mg/g,对As(III)的饱和吸附量达到了88.35、93.18、103.83 mg/g;计算不同温度下吸附反应的热力学参数,能求得热力学参数ΔG0、ΔH0、ΔS0,可见该材料吸附As(V)和As(III)为自发的吸热过程。吸附实验在前480 min内吸附速率较快,在720 min后趋于稳定;As(V)和As(III)的吸附过程用准一级动力学方程和准二级动力学方程拟合,其相关系数R2均达到了0.98以上。改变p H和离子强度考察其对砷吸附的影响,结果显示过酸或过碱都会影响到砷的吸附,p H 6~8时吸附量达到最大;离子强度的变化对As(V)、As(III)的吸附影响并不大,可能是因为As(V)、As(III)与材料形成了内层络合物。水中常见的离子中Ca2+、Mg2+对吸附几乎没影响,高浓度的HCO32-、F-、Si O32-、PO43-会对As(V)和As(III)造成较大的影响,且对As(III)的吸附性能影响大于As(V)。采用铁铜镧复合氧化物对吉林省某河流水体进行吸附处理,确定材料对砷的吸附效果。若材料的投加量越大,水中剩余的砷含量则越低,当材料投加量超过30 mg/L时吸附后即可满足饮用水砷浓度标准。对实际水体进行吸附动力学实验,发现铁铜镧复合氧化物对实际水体中砷的吸附符合准二级动力学模型,在前60 min内吸附速率非常快,吸附120 min后便使水体中砷含量低于10μg/L(国际饮用水标准砷含量上限)。处理一吨实际水体的成本为1.74元。
[Abstract]:The arsenical toxicity of arsenic has attracted the attention of many countries. In 2006, the concentration of arsenic in drinking water was adjusted to 10 mu g/L in China. The more strict standard also further promoted the research of arsenic removal technology. In the arsenic removal technology, the adsorption method has been extensively studied because of the economical and effective characteristics, and the adsorbent is used as absorption. At the core of the method, how to develop a highly efficient adsorbant for arsenic removal is the current research focus. This study aims to combine the magnetic separation properties of magnetic iron oxides, the large application range of copper oxide and the strong adsorption capacity of lanthanum oxide on arsenic, and to prepare the iron, copper and lanthanum compound oxide which can combine the three best points and adsorb arsenic on it. A series of iron copper and lanthanum oxide adsorbents were prepared by chemical coprecipitation method. The adsorption effects of adsorbents on As (V) and As (III) in water were compared. The ratio of iron, copper and lanthanum was determined to be 2:1:4, the aging temperature was 50, and the drying temperature was 80. Fe3O4, Fe Cu2O4, La (OH) 3 and Cu O. have a BET surface area of 27.89m2 /g, and the average pore size is 32.295 nm (4V/S). The isoelectric point of the material is 7.2, when the material may contain the anti cubic spinel type, and the material may contain the BET surface area of the material with 27.89m2 /g. The surface of the material is positive on the surface of P H7.2. The coercive force of the material is determined to be 50.109 emu/g by the hysteresis loop. The best fitting effect of the.Langmuir model to the adsorption process of As (V) and As (III) through the permanent magnet can be quickly separated through the permanent magnet, and the correlation coefficient R2 is above 0.97, and the temperature of the 15,25,35 is at the 15,25,35 temperature. The saturated adsorption capacity of As (V) reached 116.59138.26155.58 mg/g, respectively, and the saturated adsorption capacity of As (III) reached 88.35,93.18103.83 mg/g. The thermodynamic parameters of the adsorption reaction at different temperatures could be calculated. The thermodynamic parameters, Delta G0, Delta H0, and delta S0, can be obtained. The adsorption rate was faster in the first 480 min and stable after 720 min; the adsorption process of As (V) and As (III) was fitted with quasi first order kinetic equation and quasi two order kinetic equation, and the correlation coefficient R2 reached over 0.98. The effect of P H and ionic strength on arsenic adsorption was changed, and the results showed that both excess acid or excess alkali would affect the absorption of arsenic. The adsorption capacity of P H 6~8 reaches the maximum, and the changes in ionic strength have little influence on the adsorption of As (V) and As (III). It is probably because As (V), As (III) forms an inner complex with the material. The adsorption of As (III) is greater than that of As (V). The adsorption effect of iron copper and lanthanum compound oxide on the water of a river in Jilin province is used to determine the adsorption effect of the material on arsenic. If the amount of material is increased, the residual arsenic content in water is lower, and the adsorption of arsenic in drinking water can be satisfied when the amount of material is more than 30 mg/L. The adsorption kinetics experiment was carried out in the actual water body. It was found that the adsorption of arsenic in the actual water body was in accordance with the quasi two order kinetic model. The adsorption rate was very fast in the first 60 min. After the adsorption 120 min, the arsenic content in the water body was less than 10 mu g/L (the limit of arsenic content in the international drinking water standard). The cost of treating a ton of actual water body was 1.7. 4 yuan.
【学位授予单位】：哈尔滨工业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TU991.2;O647.3
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本文编号：2090583