Department of Soil and Water Sciences, The Robert H. Smith Faculty of Agriculture, Food and Environment, The Hebrew University of Jerusalem, Israel.
Environ Sci Technol. 2010 Jun 1;44(11):4203-9. doi: 10.1021/es1007593.
Phenolic acids participate in various soil processes and are of great concern due to their allelopathic activity. The interactions of phenolic acids (ferulic, p-coumaric, syringic, and vanillic) with montmorillonite enriched with Fe(III) was investigated. Adsorption of the phenolic acids on Fe(III)-montmorillonite was accompanied by their oxidative transformation and formation of Fe(II). Oxidative transformation of phenolic acids was affected by their molecular structure. The order of maximal transformation at the initial acid concentration of 20 mg/L on the surface of Fe(III)-montmorillonite was ferulic (94%), syringic (60%), p-coumaric (35%), and vanillic (25%). Benzoic acid which was used as a reference aromatic compound exhibited only 5% transformation. Removal of the phenolic acids from solution increased with decreasing pH. LC-MS analysis demonstrated the presence of dimers, trimers, and tetramers of ferulic acid on the surface of Fe(III)-montmorillonite. Oxidation and transformation of ferulic acid were more intense on the surface of Fe(III)-montmorillonite as compared to Fe(III) in solution due to stronger complexation on the clay surface. The results of the current study demonstrate the importance of Fe(III)-clay surfaces for the abiotic formation of humic materials and for the transformation of aromatic (phenolic) pollutants.
酚酸参与各种土壤过程，由于其化感活性而受到极大关注。本研究考察了富铁蒙脱石与酚酸（阿魏酸、对香豆酸、丁香酸和香草酸）的相互作用。酚酸在富铁蒙脱石上的吸附伴随着它们的氧化转化和 Fe(II)的形成。酚酸的氧化转化受其分子结构的影响。在初始酸浓度为 20mg/L 的条件下，在 Fe(III)-蒙脱石表面上最大转化的顺序为阿魏酸（94%）、丁香酸（60%）、对香豆酸（35%）和香草酸（25%）。作为参考芳香族化合物的苯甲酸仅转化了 5%。随着 pH 值的降低，酚酸从溶液中的去除率增加。LC-MS 分析表明，在 Fe(III)-蒙脱石表面存在阿魏酸的二聚体、三聚体和四聚体。与溶液中的 Fe(III)相比，由于在粘土表面上更强的络合作用，阿魏酸在 Fe(III)-蒙脱石表面上的氧化和转化更为强烈。本研究的结果表明，Fe(III)-粘土表面对于无生命形成腐殖质物质和芳香（酚类）污染物的转化具有重要意义。
