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Amine-modified SBA-15 (prepared by co-condensation) for adsorption of copper from aqueous solutions.

机译：胺改性的SBA-15（通过共缩合制备），用于从水溶液中吸附铜。

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摘要

During the last few decades, concerns about water shortages and pollution have increased. Consequently, environmental legislations and regulations for wastewater discharge have been issued. The objective of this work was to contribute in developing an efficient adsorbent for removing heavy metal ions from wastewater. The thesis focused on evaluating amine-modified SBA-15 as copper and other heavy metal ions adsorbent, by determining a variety of adsorptive properties with the aim of gaining a deep understanding of its behavior and to outline its advantages and limitations.;The influence of synthesis conditions on the mesostructural stability of the resultant materials after different water treatments was systematically investigated. N2 adsorption results indicated that the material prepared via co-condensation and aged at 100 °C was not stable and lost its ordered mesoporous structure after contacting water even at room temperature. Aging at 130 °C and addition of inorganic salts resulted in materials that maintained their mesporous structure under different water treatments. The material synthesized in the presence of KCl was used as adsorbent for the rest of the thesis work. It was shown that the structural collapse observed in amine-modified SBA-15 prepared by conventional method when contacted with aqueous solutions is associated with the drying process, and not the treatment itself. This structural collapse was avoided by replacing water with more volatile liquids such as acetone, before drying.;Amino-functionalized SBA-15 was tested for the removal of copper ions from aqueous solutions under different temperatures, pH, initial concentrations and agitation speeds. The obtained results indicated that the amino-functionalized SBA-15 was very efficient and equilibrium was achieved in less than 30 min at room temperature. The adsorption capacity increased dramatically with increasing temperature, initial copper concentration and pH. Under suitable conditions, the material exhibited high adsorption capacity even at very low copper concentration.;To further investigate the effect of adsorption parameters, a 2 4 factorial design experiments were used to screen the factors affecting the copper removal efficiency. All the parameters main effects were significant within a 95 % confidence level. Surface composite design was used to develop a reliable model representing the adsorption process. The statistical tests used proved the adequacy of the second order model. Optimization of the factors levels was carried out and the recommended optimum conditions are: copper concentration of 20 mg/L, adsorbent/solution ratio of 1.57 g/L, pH of 6.5, and T = 294 K with 95% copper removal.;The effect of regeneration conditions was investigated after three adsorption–desorption cycles, under different batchwise regeneration conditions. Using a composite surface design methodology, the effect of the regeneration conditions on the performance of the adsorbent was investigated. It was found that all the studied parameters have a statistically significant influence on the working adsorption capacity. With respect to structural properties and amine content, none of the factors was found to be significant. Regeneration using EDTA was found to be more efficient than acid treatment.;Amino-functionalized SBA-15 was studied as potential absorbent for Cd 2 +, Co2 +, Cu2 +, Zn2 +, Pb2 +, Ni2 +, Al3+ and Cr 3 +. The adsorption capacity and selectivity of the material were investigated in single and multi-metal solutions. Using very dilute solutions, i.e., 10 ppm, more than 95% of cations were removed, except for Co 2+ and Cr3 +, indicating the high sensitivity of the current adsorbent. The adsorption capacities in multi-metal solutions were lower than in single-metal ones because of competition between metallic elements for the amine groups. The adsorbent was not affected in the presence of sodium, potassium, and calcium, indicating that the ionic strength does not affect the adsorption properties. Application of this material to remove copper in tap water, river water, and electroplating wastewater was shown to be successful.;Dynamic experiments were carried out on the adsorption of copper ions in a laboratory packed-bed of amine-modified SBA-15. Breakthrough curves were analyzed at different flowrates and after two adsorption-desorption cycles. Furthermore, a model based on mass balance was developed and tested for predicting the breakthrough curves under different experimental conditions used. The results suggested that the developed model was in good agreement with the experimental data. Bed regeneration was performed by circulating 0.2 M EDTA solution through the column for 30 min.
机译：在过去的几十年中，人们对水资源短缺和污染的担忧日益增加。因此，已经发布了废水排放的环境法规。这项工作的目的是为开发一种有效的吸附剂以去除废水中的重金属离子做出贡献。本文旨在通过确定各种吸附性能来评估胺改性的SBA-15作为铜和其他重金属离子的吸附剂，以深入了解其行为并概述其优势和局限性。系统研究了不同水处理条件下合成条件对所得材料介观结构稳定性的影响。 N 2的吸附结果表明，即使在室温下，与水缩合后在100°C老化的材料也不稳定，失去了有序的介孔结构。在130°C时效和添加无机盐后，材料在不同的水处理条件下仍保持其中孔结构。在其余的论文工作中，将在氯化钾存在下合成的材料用作吸附剂。结果表明，通过常规方法制备的胺改性的SBA-15与水溶液接触时观察到的结构塌陷与干燥过程有关，与处理本身无关。通过在干燥之前用更具挥发性的液体（例如丙酮）代替水，可以避免这种结构塌陷。在不同温度，pH，初始浓度和搅拌速度下，对氨基官能化SBA-15进行了水溶液中铜离子的去除测试。所得结果表明，氨基官能化的SBA-15非常有效，并且在室温下不到30分钟即可达到平衡。随着温度，初始铜浓度和pH值的增加，吸附容量急剧增加。在合适的条件下，即使在非常低的铜浓度下，该材料也显示出高的吸附容量。为了进一步研究吸附参数的影响，我们采用了2 4析因设计实验来筛选影响除铜效率的因素。所有参数的主要影响在95％的置信度内均显着。表面复合材料设计用于开发代表吸附过程的可靠模型。所使用的统计检验证明了二阶模型的充分性。进行了因素水平的优化，建议的最佳条件是：铜浓度为20 mg / L，吸附剂/溶液比为1.57 g / L，pH为6.5，T = 294 K，铜去除率达95％;在不同的分批再生条件下，经过三个吸附-解吸循环后，研究了再生条件的影响。使用复合材料表面设计方法，研究了再生条件对吸附剂性能的影响。发现所有研究的参数对工作吸附容量具有统计学上显着的影响。关于结构性质和胺含量，没有发现重要因素。发现使用EDTA再生比酸处理更有效。研究了氨基官能化SBA-15作为Cd 2 +，Co2 +，Cu2 +，Zn2 +，Pb2 +，Ni2 +，Al3 +和Cr 3 +的潜在吸收剂。在单金属和多金属溶液中研究了该材料的吸附能力和选择性。使用非常稀的溶液（即10 ppm），除Co 2+和Cr3 +以外，已去除了超过95％的阳离子，表明该吸附剂具有很高的灵敏度。由于金属元素之间对胺基的竞争，多金属溶液中的吸附能力低于单金属溶液。在钠，钾和钙的存在下，吸附剂未受影响，表明离子强度不影响吸附性能。该材料用于去除自来水，河水和电镀废水中的铜已被证明是成功的。在胺修饰的SBA-15实验室填充床中进行了铜离子吸附的动态实验。在不同的流速下以及两个吸附-解吸循环后分析了穿透曲线。此外，开发了基于质量平衡的模型并进行了测试，以预测在使用的不同实验条件下的穿透曲线。结果表明，所开发的模型与实验数据吻合良好。通过使0.2 M EDTA溶液循环流过色谱柱30分钟来进行床层再生。

著录项

  • 作者

    Da'na, Enshirah.;

  • 作者单位

    University of Ottawa (Canada).;

  • 授予单位 University of Ottawa (Canada).;
  • 学科 Chemistry Inorganic.;Engineering Chemical.
  • 学位 Ph.D.
  • 年度 2012
  • 页码 199 p.
  • 总页数 199
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

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