碳质材料吸附剂的改性及其对水中阴离子污染物的吸附研究

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	碳质材料吸附剂的改性及其对水中阴离子污染物的吸附研究
其他题名	Modification of carbon-based adsorbents and their adsorption for anionic pollutants in water
	黄一敏
学位类型	博士
导师	李心清
	2019
学位授予单位	中国科学院大学
学位授予地点	中国科学院地球化学研究所
关键词	生物炭碳纳米管铬磷酸盐吸附
摘要	铬污染给全世界的水生环境带来了越来越多的问题，特别是在工业区和采矿领域。迄今为止，通过使用各种技术，例如化学沉淀，溶剂萃取和电渗析，已经实现了 Cr（VI）的去除。然而，这些方法通常需要更长的反应时间，昂贵和复杂的准备过程。在本文中，展示了一种简单的聚合物交联方法，用于在水溶液中有效且快速地除去 Cr（VI）阴离子物质。具体而言，用壳聚糖改性羧化多壁碳纳米管（MWCNTs-COOH），以增强 Cr（VI）在酸性水溶液（pH = 2）中的吸附，在 293K，303K 和 313K 下，最大吸附容量分别为 142.9±0.9 mg g -1， 151±1mg g-1和 164±2mg g-1。吸附数据遵循 Langmuir 等温模型，说明吸附过程是放热的。同时，研究结果发现复合材料对 Cr（VI）的吸附主要是通过物理静电吸附以及化学氧化还原反应引起的。此外，壳聚糖/ MWCNTs-COOH 复合物被证明可成功应用于多次Cr（VI）吸附循环，没有或仅有限的性能损失（直至第 4 个循环的吸附率仍为 98-100％）。除此之外，这种壳聚糖改性的 MWCNTs-COOH 复合物不仅提高对 Cr（VI）吸附容量，而且有效缩短了去除 Cr（VI）所需的吸附反应时间。总的来说，本文的研究提供了一种简单而快速的方法来设计和制造新材料，这种材料将在许多环境应用中发挥重要作用，例如废水处理和化学废物管理。磷是水生环境富营养化的罪魁祸首，主要以磷酸盐的形式溶解在水中。因此，很难从水中去除。目前许多研究正在探索不同的材料，旨在实现提高对磷的去除能力。同时，磷的回收能力也需要被考虑，因为废水中存在的磷可以作为矿物磷的潜在替代资源。碳纳米管是有潜力用于治理磷酸盐污染的。然而，目前关于它们去除磷的潜力的研究是有限的。本文中，通过简单的交联，用壳聚糖对多壁碳纳米管进行改性，以获得用于除去磷酸盐的新型吸附剂。研究数据显示，壳聚糖改性的碳纳米管，在 pH 3 和 293 K 下，在 30 分钟内达到 36.1±0.3 mg P g-1的最大吸附量。即使经过 5 次吸附 - 解吸循环，复合物（壳聚糖/多壁碳纳米管）的吸附容量仍可保持在 94-98％。根据 Freundlich 等温线模型，该吸附过程是放热过程。与其他已经被报道的新型磷酸盐去除剂相比，该复合材料具有很大的优势，表明该复合材料是一种非常有潜力的吸附剂来处理磷引起的水体富营养化。除此之外，文中还探讨了用壳聚糖，季铵盐和镧改性麦秆生物炭，以增强相关环境条件下的磷酸盐去除。具体而言，使用新的胺保护的交联方法来改性生物炭，对磷的最大吸附容量可达到 109±4mg P g-1。即使在较宽的温度范围（15-45℃）和 pH（2.5-7）范围内，被改性生物炭去除磷酸盐的高吸附性能也没有受到显著的影响。对于 100mg P L-1 的磷酸盐溶液，制备的复合材料在 30 分钟就能达到 100％的吸附平衡，对于 25mg P L-1的磷酸盐溶液，30 分钟达到吸附平衡的93％，与先前报道相比，吸附平衡时间被显著的缩短了。复合材料的吸附机理主要包括静电相互作用，配体交换和路易斯酸碱相互作用。所有上述优点使得制备的复合生物炭吸附材料对于磷酸盐的去除具有极大的潜力。
其他摘要	Chromium pollution has posed an increasing problem to the aquatic environment worldwide, especially in industrial areas and mining fields. To date, the removal of Cr (VI) has been achieved by using various techniques such as chemical precipitation, solvent extraction, and electrodialysis; however, these methods typically take significantly longer reaction time and expensive, complex preparations. Herein, we demonstrate a simple polymer crosslinking method for efficient and fast removal of Cr(VI) anionic species via adsorption in aqueous solutions. Specifically, we modified carboxylated multi-walled carbon nanotubes (MWCNTs-COOH) with chitosan to enable enhanced adsorption of Cr (VI) in acidic aqueous solutions (pH= 2), resulting in maximum adsorption capacities of 142.9 ± 0.9 mg g−1 , 151 ± 1 mg g−1 and 164 ± 2 mg g−1 at 293 K, 303 K and 313 K, respectively. The adsorption process was exothermic, following the Langmuir isotherm model. We found that the adsorption of Cr (VI) by the composite is caused primarily through physical electrostatic adsorption as well as chemical redox reactions. Furthermore, the chitosan/MWCNTs-COOH composite was demonstrated to be successfully applicable in multiple Cr (VI) adsorption cycles, with none, or limited, loss of performance (98–100% adsorption up to the 4th cycle). Nonetheless, this chitosan-modified MWCNTs-COOH composite is capable of enhancing the adsorption capacity, as well as shortening the adsorption reaction time needed for efficient Cr (VI) removal to occur. Overall, our work presents a simple and rapid methodology in designing and fabricating new materials that will find significant utility in a number of environmental applications, such as wastewater treatment and chemical waste management. Phosphorus, a major culprit for eutrophication of aquatic environments, is dissolved in water primarily in the form of phosphate; hence, it is difficult to remove, and different materials are being investigated, aiming at high removal capabilities. Meanwhile, recovery capability must also be considered, since phosphorus present in wastewater may serve as a potential alternative resource for the mineral phosphorus. Carbon nanotubes are promising for the treatment of phosphate pollution; however, studies about their removal potential are limited. Herein, multi-walled carbon nanotubes were modified with chitosan through simply cross-linking to obtain a novel adsorbent for phosphate removal.Our data show that a maximum adsorption as high as 36.1 ± 0.3 mg P g-1 was achieved in 30 min at pH 3 and 293 K. The adsorption capacity of the composite (chitosan/multi walled carbon nanotubes) could be maintained at 94–98% even after 5 adsorption– desorption cycles. An exothermic process was obtained, according to the Freundlich isotherm model. Based on the reported performance, the composite has a great advantage compared with other novel adsorbents for phosphate removal, indicating that the composite is a highly potential material to treat phosphorus-induced eutrophication of water bodies. In addition, we explored the modification of wheat straw biochar with chitosan, quaternary ammonium salt, and lanthanum for enhanced phosphate removal in environmentally relevant conditions. Specifically, a new amine protected cross-linking method was utilized to modify the absorbent material for maximum adsorption capacity, reaching 109±4 mg P g-1 . The high phosphate removal performance of the composite was not significantly affected in a broad range of temperature (15-45˚C) and pH (2.5-7). 30 min allowed reaching a 100 % adsorption equilibrium for 100 mg P L-1 , and 93% for 25 mg P L-1 , thus, significantly reducing the treatment time compared to previous reports. The adsorption mechanisms of the composite are extensively described, where electrostatic interaction, Ligand exchange and Lewis acid-base interaction contribute to the process. All the above-mentioned advantages make the prepared composite of great interest for the on-site phosphate removal.
页数	144
语种	中文
文献类型	学位论文
条目标识符	http://ir.gyig.ac.cn/handle/42920512-1/10772
专题	研究生
推荐引用方式 GB/T 7714	黄一敏. 碳质材料吸附剂的改性及其对水中阴离子污染物的吸附研究[D]. 中国科学院地球化学研究所. 中国科学院大学,2019.

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