SBIR Phase I: Removal of Toxic Microcystins in Water Using Graphite Nanofibers

SBIR 第一阶段：使用石墨纳米纤维去除水中的有毒微囊藻毒素

• 批准号: 0441090
• 负责人: Xuejun Xu
• 金额: $ 9.99万
• 依托单位: CATALYTIC MATERIALS LLC
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2005
• 资助国家: 美国
• 起止时间: 2005-01-01 至 2005-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0441090&HistoricalAwards=false
• 关键词: SBIR; Phase; Removal; Toxic; Microcystins

This Small Business Innovation Research (SBIR) Phase I project deals with the use of graphite nanofibers (GNF) as novel adsorption media for the removal of bio-toxins from water. Specifically, the research will focus on the removal of microcystin-LR, a potential biological weapon that could be used by terrorists to attack human beings. Various methods have been proposed for the removal of microcystins from aqueous media, including adsorption by activated carbon, chlorination, ozonation, permanganate, hydrogen peroxide, photolysis, and semiconductor photo-catalysis. Of these approaches, the activated carbon treatment appears to be one of the most effective procedures. Various microcystins can be adsorbed on the porous surface of activated carbon and the efficiency of removal depends upon the pore size and surface functionality. It is claimed that the dominant factor in the adsorption process is the volume of mesopores (2-50 nm diameter) rather than the volume of micropores (diameter 2 nm) or megapores (diameter 50nm). In addition, the removal efficiency gradually decreases over a period of time due to the accumulation of a bio-film on the activated carbon surface. The regeneration of the spent activated carbon is not a simple task and as consequently the contaminated material is frequently discarded. Improper disposal procedures of used activated carbons could give rise to serious problems because microcystins are known to persist for many years when stored in dry conditions at room temperature and to withstand many hours of boiling in water. Since GNF contain an abundance of edge sites, the surface functionality can easily be transformed to give either hydrophobic to hydrophilic properties. In addition, it has recently been discovered that following suitable thermal treatments it is possible to generate GNF structures that possess a large fraction of mesopores having average dimensions of 12 nm. This unusual blend of properties makes GNF ideal candidates for the adsorption of microcystins from water. Furthermore, the high degree of crystalline perfection exhibited by GNF enables one to heat the materials in the presence of oxidizing gases to temperatures in excess of 500 C, thereby allowing for the removal of trapped microcystins and the regeneration of the adsorbate.

这个小型企业创新研究(SBIR)第一阶段项目涉及使用石墨纳米纤维(GNF)作为新型吸附介质来去除水中的生物毒素。具体地说，这项研究将集中在清除微囊藻毒素-LR，这是一种潜在的生物武器，可能被恐怖分子用来攻击人类。人们提出了各种方法来去除水介质中的微囊藻毒素，包括活性炭吸附、氯化、臭氧氧化、高锰酸盐、过氧化氢、光解和半导体光催化。在这些方法中，活性碳处理似乎是最有效的程序之一。微囊藻毒素可以吸附在活性碳多孔性表面，其去除效率取决于孔径大小和表面官能度。认为影响吸附过程的主要因素是中孔(直径2-50 nm)的体积，而不是微孔(直径2 nm)或大孔(直径50 nm)的体积。此外，由于生物膜在活性碳表面的积累，随着时间的推移，去除效率逐渐下降。废活性碳的再生并不是一项简单的任务，因此，被污染的材料经常被丢弃。对用过的活性碳的不当处置程序可能会导致严重的问题，因为众所周知，微囊藻毒素在室温下储存在干燥条件下会持续多年，并在水中沸腾数小时。由于GNF含有丰富的边缘位置，表面官能团可以很容易地转变为疏水到亲水的性质。此外，最近发现，经过适当的热处理后，有可能产生具有较大比例的平均尺寸为12 nm的介孔的GNF结构。这种不同寻常的混合性质使GNF成为从水中吸附微囊藻毒素的理想候选者。此外，GNF表现出的高度结晶完整性使人们能够在氧化气体存在的情况下将材料加热到500摄氏度以上，从而能够去除捕获的微囊藻毒素并再生吸附物。