土壤中氧化铁的有机还原溶解动力学

KINETICS OF REDUCTION AND DISSOLUTION OF IRON OXIDES IN SOILS BY ORGANIC COMPOUNDS

研究了土壤中的氧化铁被两种酚化合物还原而溶解的动力学，结果表明，在ｐＨ恒定和有机还原剂过量的情况下，氧化铁的还原溶解符合一级反应动力学方程，还原溶解速率大小与土壤中氧化铁的结晶形态有关．氧化锰的存在影响着氧化铁的还原溶解，在存在足够的还原剂的条件下，两者可同时还原．实验中求得黄壤和赤红壤中氧化铁的还原溶解反应对［Ｈ＋］的反应级数分别为０．１２６和０．１７４。土壤中氧化铁的还原溶解是一个受表面反应控制的过程，反应的速率控制步骤是表面的电子转移反应，磷酸根在土壤中的吸附占据了氧化铁表面的反应位，因而明显抑制还原溶解反应．

This paper has dealt with the kinetics of the reductive dissolution of iron oxides in soils by two phenolic compounds and experimental results have shown that the rate of reductive dissolution of iron oxides in soils by excessive reductant at contant pH follows the equation of the first order reaction. The rate of reductive dissolution varies with the forms of iron oxides in soils. Manganese oxides affect the reductive dissolution of iron oxides in soils and both manganese oxides and iron oxides can be reduced simulataneously by excessive reductant. The order of the reaction of iron oxides in yellow soil and latored soil with respect to [H+] is 0. 126 and 0. 174, respectively. The reductive dissolution of iron oxides in soils involves the reaction of surface chemistry and the rate of the reductive dissolution is controlled by electron transfer reaction on surface of iron oxides in soils. The phosphate adsorped by soil may occupy part of the adsorption sites on surface of iron oxides and low the rate of the reductive dissolution of iron oxides in soils.