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

生物吸附，即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经济有效的方法。由于微生物去除水溶液中金属离子的能力得到了广泛的研究，真菌被认为是一类很有前途的低成本金属离子吸附剂。寡孢根霉对甲烷、铜、钴的吸附性能对其液体发酵条件进行了研究。在罗奥戈人中间。物种，奥立戈先生。P12菌丝体对金属离子的吸附能力最高，达到3.2 mmol/g菌丝体，与传统的离子交换小球相当。从吸附等温线、Freundlich曲线和Scatchard图分析，确定了寡糖中的几种官能团。发现P12对金属的吸附有贡献。PH依赖性的斜率分析表明，离子交换不是菌丝体与铜、镧、钴等金属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对金属的吸附。为了阐明多糖的超分子结构与金属吸附能力的关系，我们对不同种类的含有多糖的生物质进行了吸附实验。例如，我们利用含有多个羟基的纤维素作为Sb(III)的吸附剂。纤维素对Sb(III)的最大吸附量为5.2 mg/g。两个多元醇链中相邻的两个羟基位于纤维素的葡萄糖单元中，纤维素可以通过游离的羟基，即非氢键形成的羟基来捕获Sb(III)。

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.