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土壤腐植物质的提取、纯化和分级操作是用它们的化学组成、功能基团含量、电荷特点和分子大小及形状的现代知识来解释的。从泥炭或矿质土壤中提取腐植物质需要使腐植物质不溶的阳离子被取代并拆散缔合。在水体系中,高价阳离子必须被取代或络合并代之以单价阳离子,后者生成的盐易于解离并在分子内产生相当量的负电荷。由此造成的分子内和分子间的电荷推拒导致腐植分子的膨胀、水化和溶解,水可提取性受腐植大分子的电荷密度、分子大小和疏水特性的约束。 非水溶剂的提取,必须以H~+取代金属离子并保持低pH以压抑解离。在这样的条件下,偶极性的非质子溶剂,诸如DMSO,是有效提取剂。 腐植物质的分级是基于这样的事实,即它们在溶解度、分子大小、电荷密度和吸附性质上存在一个数值范围。
Soil humic substances are extracted, purified, and fractionated using modern knowledge of their chemical composition, functional group content, charge characteristics, and molecular size and shape. Extracting humic substances from peat or mineral soils requires the humus-insoluble cations to be replaced and disassociated. In aqueous systems, the high-valent cation must be replaced or complexed and replaced by a monovalent cation, which generates a salt that readily dissociates and produces a significant amount of negative charge within the molecule. The resulting intramolecular and intermolecular charge reversal results in the swelling, hydration and dissolution of the humic molecules, and the water extractability is constrained by the charge density, molecular size, and hydrophobic character of the humified macromolecules. Non-aqueous solvent extraction, H ~ + must be replaced by metal ions and maintain low pH to suppress dissociation. Under such conditions dipolar aprotic solvents, such as DMSO, are effective extractants. The grading of humic substances is based on the fact that they have a numerical range in terms of solubility, molecular size, charge density and adsorption properties.