Influence of the physicochemical properties of clay minerals on the degree of darkening via polycondensation reactions between catechol and glycine
Influence of the physicochemical properties of clay minerals on the degree of darkening via polycondensation reactions between catechol and glycine
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DOI：
10.1016/j.clay.2009.08.017
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发表时间：
2009-11
影响因子：
5.6
通讯作者：
A. Miura;R. Okabe;K. Izumo;M. Fukushima
中科院分区：
文献类型：
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作者：
A. Miura;R. Okabe;K. Izumo;M. Fukushima
氨基酸与酚类化合物的缩聚反应是腐殖化的重要途径，粘土矿物具有催化作用。本文研究了几种粘土矿物的物理化学性质对邻苯二酚（CT）和甘氨酸（Gly）缩聚反应的影响。CT和Gly的缩聚使用在600nm处的比吸光度（E600）作为变暗程度的量度来评价。在本研究中使用了以下材料：高岭土、膨润土、沸石、卡努马土（脲基土）和硅酸铝。在卡努马土壤、膨润土和沸石的存在下，与对照（不含粘土的CT + Gly）相比，变暗的程度显著增强，清楚地表明这些粘土矿物能够充当有效的催化剂。这些粘土矿物的特点是：具有较高的比表面积和较高的铁、钛、钙含量。粘土矿物中的过渡金属（Fe和Ti）可作为刘易斯酸，而二价碱土金属（Ca）可促成布朗斯台德酸位点的出现。因此，粘土矿物中这些金属的含量是通过氨基酸和酚类之间的缩聚反应增强变暗的重要因素。
Polycondensation reactions between amino acids and phenols are an important pathway for humification, and clay minerals are able to catalyze these reactions. In the present study, we investigated the influence of the physicochemical properties of some clay minerals on polycondensation reactions between catechol (CT) and glycine (Gly). The polycondensation of CT and Gly was evaluated using the specific absorbance at 600nm (E600) as a measure of the degree of darkening. The following materials were used in the present study: kaolin, bentonite, zeolite, Kanuma soil (allophanic soil) and aluminum silicate. In the presence of Kanuma soil, bentonite and zeolite, the degree of darkening was significantly enhanced, compared to the control (CT + Gly without clay), clearly showing that these clay minerals are able to serve as effective catalysts. The characteristics of these clay minerals were as follows: higher levels of specific surface area, and higher Fe, Ti and Ca contents. Transition metals (Fe and Ti) in the clay minerals can serve as Lewis acids, and divalent alkaline-earth metals (Ca) can contribute to the appearance of Brønsted acid sites. Therefore, contents of such metals in clay minerals are important factors in terms of enhancing darkening via polycondensation reactions between amino acids and phenols.