功能化改性水滑石吸附阴离子污染物的性能研究

发布时间：2018-06-12 21:56

本文选题：水滑石 + 功能化改性　；参考：《济南大学》2015年硕士论文

【摘要】：近年来,水滑石类化合物(Layered Double Hydroxide,LDH)作为一种新型的吸附剂,由于具有独特的层状结构和物化特性,成为国内外研究的热点。然而,对水滑石进行功能化改性后用来吸附阴离子污染物的研究比较少。本文选择磷酸根和铬酸根作为目标污染物,制备了不同类型的功能化改性水滑石,采用静态吸附的方法去除水中磷酸根和铬酸根。具体研究结果如下:(1)利用共沉淀法合成了Mg-Al-LDH和Zn-Al-LDH,并对其进行了XRD、BET、FTIR和Zeta电位的表征,结果表明水滑石样品的晶型比较完整,Zn-Al-LDH的比表面积大于Mg-Al-LDH。考察了吸附剂用量、吸附时间、初始溶液pH值对吸附磷酸根的影响,得到水滑石的最佳用量为4 g/L Mg-Al-LDH和1.6 g/L Zn-Al-LDH,振荡40 min后达到平衡,在强碱性条件下,吸附能力下降。采用拟一级和拟二级动力学对实验数据进行拟合,Mg-Al-LDH和Zn-Al-LDH吸附磷酸根的过程更符合拟二级动力学。对吸附过程进行等温线拟合,都符合Freundlich和Langmuir模型,Zn-Al-LDH的最大吸附量大于Mg-Al-LDH。对吸附前和吸附后水滑石的FTIR、Zeta电位进行了表征,可以解释吸附机理为静电作用、离子交换作用和配合作用。(2)采用水热法合成了Fe3O4,以其为基质,用共沉淀法合成了具有磁性核壳结构的Fe3O4@Zn-Al-,Fe3O4@Mg-Al-和Fe3O4@Ni-Al-LDH,并对样品进行了XRD、BET、FTIR、VSM和Zeta电位表征。考察了吸附剂用量、吸附时间、初始溶液pH值对吸附磷酸根性能的影响,得到吸附最佳条件为:Fe3O4@LDHs的最佳用量为2 g/L,振荡60min,调节pH=3,讨论了不同pH条件下可能发生的吸附机理。采用拟一级、拟二级动力学和KASRA模型对动力学数据进行了分析,Fe3O4@LDHs吸附磷酸根的过程更符合拟二级动力学。采用ARIAN模型对吸附等温线进行了讨论,利用Freundlich、Langmuir和Temkin模型对实验数据进行了拟合,发现更符合Langmuir模型,Fe3O4@Zn-Al-LDH的最大吸附量大于Fe3O4@Mg-Al-LDH和Fe3O4@Ni-Al-LDH。对吸附热力学进行了研究,结果表明吸附反应是自发的、吸热的和熵增加的反应。Fe3O4@LDHs吸附磷酸根后能够用磁铁在10 s之内进行快速分离。(3)采用共沉淀法合成了Zn-Al-LDH和Fe3O4@Zn-Al-LDH,然后进行500°C焙烧(Zn-Al-500-LDO和Fe3O4/Zn-Al-500-LDO)。对样品进行了XRD和FTIR的表征,经过焙烧后,层间的CO32-消失,通过水滑石的“记忆效应”,能够恢复层状结构。考察了吸附剂用量、吸附时间、初始溶液pH值对吸附铬酸根性能的影响,得到了吸附最佳条件:焙烧水滑石最佳用量为2 g/L,振荡60 min,调节溶液pH=3。采用拟一级、拟二级动力学模型对吸附动力学数据进行了拟合,Zn-Al-500-LDO和Fe3O4/Zn-Al-500-LDO吸附铬酸根的过程更符合拟二级动力学。采用Freundlich和Langmuir模型对实验数据进行拟合,发现吸附过程更符合Langmuir模型。吸附反应是自发的、吸热的和熵增加的反应。经过焙烧之后,Zn-Al-500-LDO和Fe3O4/Zn-Al-500-LDO吸附铬酸根的吸附能力大于Zn-Al-LDH和Fe3O4@Zn-Al-LDH,是一种有潜在应用前景的吸附剂。本论文以功能化改性的水滑石为吸附剂,以吸附去除造成水体富营养化的磷酸根和显著毒性的铬酸根,获得了良好的效果,为阴离子污染物的去除提供了有益的理论依据。
[Abstract]:In recent years, Layered Double Hydroxide (LDH), as a new type of adsorbent, has become a hot spot of research at home and abroad because of its unique layered structure and physicochemical properties. However, there are few studies on the functionalized modification of hydrotalcite to adsorb anionic contaminants. This paper chooses phosphate and chromate roots. As the target pollutant, different types of functional Modified Hydrotalcite was prepared and the static adsorption method was used to remove phosphoric acid and chromate in water. The results were as follows: (1) Mg-Al-LDH and Zn-Al-LDH were synthesized by coprecipitation method, and the XRD, BET, FTIR and Zeta potential were characterized. The results showed the crystal form of the hydrotalcite sample. More complete, the specific surface area of Zn-Al-LDH is greater than Mg-Al-LDH.. The effect of adsorbant dosage, adsorption time and initial solution pH value on the adsorption of phosphoric acid root is investigated. The optimum amount of water talc is 4 g/L Mg-Al-LDH and 1.6 g/L Zn-Al-LDH, after oscillation 40 min, the equilibrium is reached, and the adsorption capacity decreases under the strong alkali condition. The pseudo first order and quasi two are used. The adsorption process of Mg-Al-LDH and Zn-Al-LDH is more consistent with the quasi two order kinetics. The adsorption process is fitted to the Freundlich and Langmuir models. The maximum adsorption capacity of Zn-Al-LDH is greater than Mg-Al-LDH., and the FTIR and Zeta potential before and after absorption of hydrotalcite are characterized. It can be explained that the adsorption mechanism is electrostatic, ion exchange and coordination. (2) Fe3O4 was synthesized by hydrothermal method. Fe3O4@Zn-Al-, Fe3O4@Mg-Al- and Fe3O4@Ni-Al-LDH with magnetic core and shell structure were synthesized by co precipitation method, and the samples were characterized by XRD, BET, FTIR, VSM and Zeta potential. The amount of adsorbents was investigated. The best adsorption conditions of adsorption time and initial solution pH value on Adsorption Properties of phosphate root are that the best dosage of Fe3O4@LDHs is 2 g/L, oscillating 60min, adjusting pH=3, and discussing the possible adsorption mechanism under different pH conditions. The pseudo first order, pseudo two kinetics and KASRA model are used to analyze the kinetic data and Fe3O4@LDHs absorption. The process of phosphate attached is more consistent with the quasi two order kinetics. The adsorption isotherm is discussed by ARIAN model. The experimental data are fitted with Freundlich, Langmuir and Temkin models. It is found that the Langmuir model is more consistent with the maximum adsorption capacity of Fe3O4@Zn-Al-LDH than Fe3O4@ Mg-Al-LDH and Fe3O4@Ni-Al-LDH. for adsorption thermodynamics. The results show that the adsorption reaction is spontaneous, the absorption of the endothermic and entropy increasing reaction.Fe3O4@LDHs can be quickly separated with magnets within 10 s. (3) the co precipitation method is used to synthesize Zn-Al-LDH and Fe3O4@Zn-Al-LDH, and then 500 degree C roasting (Zn-Al-500-LDO and Fe3O4/Zn-Al-500-LDO). XRD and FT are carried out on the sample. The characterization of IR, after roasting, the interlayer CO32- disappeared, through the "memory effect" of the hydrotalcite, can restore the layered structure. The effect of adsorbent dosage, adsorption time and initial solution pH value on the adsorption of chromic acid root was investigated. The best adsorption conditions were obtained: the optimum dosage of the calcite was 2 g/L, the oscillation 60 min, and the adjustment of the solution pH=3. extraction. The adsorption kinetics data were fitted by quasi two stage dynamic model. The adsorption process of Zn-Al-500-LDO and Fe3O4/Zn-Al-500-LDO was more consistent with the pseudo two kinetics. The experimental data were fitted with Freundlich and Langmuir models, and the adsorption process was more consistent with the Langmuir model. The adsorption reaction was spontaneous and endothermic. After roasting, the adsorption capacity of Zn-Al-500-LDO and Fe3O4/Zn-Al-500-LDO adsorbed chromate is greater than that of Zn-Al-LDH and Fe3O4@Zn-Al-LDH. It is a potential application of adsorbents. This paper uses functional modified hydrotalcite as an adsorbent to adsorb phosphoric acid root of eutrophication in water body and its significance. The toxic chromium acid has achieved good results, which provides a useful theoretical basis for the removal of anionic pollutants.
【学位授予单位】：济南大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：X703;O647.33

【相似文献】