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Understanding the mechanism of metal adsorption on polysaccharides possesing suparamolecular structure and molecular design of separation materials

了解超分子结构多糖的金属吸附机理和分离材料的分子设计

基本信息

批准号：
16560661
负责人：
UEZU Kazuya
金额：
$ 2.3万
依托单位：
The University of Kitakyushu
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2004
资助国家：
日本
起止时间：
2004 至 2005
项目状态：
已结题

项目摘要

Biosorption, the metal-ion adsorption process by biomass, represents a potentially cost-effective way of eliminating toxic heavy metals. As the ability of microorgamisms to remove metal ions in aqueous solution has been extensively studied, fungi have been recognized as a promising class of low-cost adsorbents for metal ions. Adsorption performance of lanthane, copper, and cobalt by Rhizopus oligosporus (Rh.oligo.) fermented in liquid media was investigated. Among the Rh.oligo. species, Rh.oligo. P12 demonstrated the highest metal-adsorption capacity of 3.2 mmol/g-mycelia, which was comparable to the conventional ion-exchange beads for wastewater treatments. From the adsorption isotherm, the Freundlich curve, and the Scatchard plot analysis, the several kinds of functional groups in Rh.oligo. P12 were found to contribute to the metal adsorption. The slope analysis of the pH dependence showed that the ion-exchange is not a dominant factor of the interactions between the mycelia and metals such as copper, lanthane and cobalt. These results indicated that the polysaccharides in cell wall were involved in the metal adsorption. We carried out the adsorption tests with various kinds of biomass containing polysaccharides in order to elucidate the relationship between the supramolecular structure of polysaccharides and the metal adsorption ability. For example, we have utilized the cellulose containing the plural hydroxyl groups as the antimony (III) adsorbent. Amount of antimony (III) adsorbed to the cellulose was 5.2mg/g at maximum. Two adjacent hydroxyl groups of two polyol moieties are in the glucose unit of cellulose, cellulose could capture antimony (III) with free hydroxyl groups, that is, non-hydrogen-bonding-forming hydroxyl groups.

生物吸附是生物质对金属离子的吸附过程，是消除有毒重金属的一种潜在的具有成本效益的方法。随着对微生物去除水溶液中金属离子能力的深入研究，真菌已被公认为一类有前途的低成本金属离子吸附剂。少孢根霉对镧、铜和钴的吸附性能在液体培养基中发酵。在Rh.olig.种、寡聚枝藻Rh.olig. P12表现出最高的金属吸附能力为3.2 mmol/g菌丝体，这是与传统的离子交换珠废水处理。通过吸附等温线、Freundlich曲线和Scatchard图分析，研究了Rh.olig.发现P12对金属吸附有贡献。pH依赖性斜率分析表明，离子交换不是菌丝体与铜、镧、钴等金属离子相互作用的主导因素。这些结果表明，细胞壁中的多糖参与了金属离子的吸附。为了阐明多糖的超分子结构与金属吸附能力之间的关系，我们对不同种类的含多糖的生物质进行了吸附试验。例如，我们已经利用含有多个羟基的纤维素作为锑（III）吸附剂。纤维素对锑（Ⅲ）的吸附量最大为5.2mg/g。纤维素的葡萄糖单元中有两个相邻的羟基，纤维素可以用自由羟基即非氢键形成的羟基捕获锑（III）。