摘要
以我国几种土壤中铁锰结核为材料 ,研究了不同pH、离子强度和温度条件下氧化锰矿物对Cr(Ⅲ )的氧化。结果表明 :随着体系pH的降低、离子强度的增加以及温度的升高 ,供试铁锰结核对Cr(Ⅲ )的氧化量增加 ,这除了与其氧化还原反应本身消耗H+有关外 ,还与氧化锰矿物表面电荷性质和电位变化、共存的氧化铁矿物有关。而上述因素的变化导致N2 1、N4 1号样氧化Cr(Ⅲ )的增幅比N5 1号样的大 ,则可能与氧化锰矿物的结晶程度、晶体构造和铁锰结核中Mn(Ⅳ )
Manganese oxide minerals are important scavenger of heavy metals and oxidants of changeable valent elements in soils and aquatic environment.Previous studies on redox reaction between Mn oxides and Cr(III) were mainly achieved by using synthetic Mn oxides,and little literature is available on redox reaction of Cr(III) and Mn oxides from soils.Fe-Mn nodules were major depositing forms of Mn in soils.Influences of pH,ion strength and temperature on the oxidation of Cr(Ⅲ) by Fe-Mn nodules from soils were investigated by means of chemical analysis and equilibrium techniques.The results showed that the amounts of Cr(Ⅲ) oxidized by Fe-Mn nodules increased as pH decreasing,ion strength and temperature increasing.It was related to charge properties and electric potential of Mn oxide surface,and coexistence of Fe oxides besides consumption of H + during redox reaction.The ranging amounts of Cr(Ⅲ) oxidized by N2-1 and N4-1 contained birnessite and lithiophorite were larger than that by N5-1 contained todorokite and lithiophorite under above conditions.These diversities were related to crystallinity,crystal structure,and Mn(Ⅳ) content of Mn oxides in Fe-Mn nodules.These data are useful for predicting chrome transport in the environment,and understanding functions of Mn oxide minerals in soil and sediment particles.
出处
《土壤学报》
CAS
CSCD
北大核心
2003年第6期852-857,共6页
Acta Pedologica Sinica
基金
国家自然科学基金 (批准号 :40 1 0 1 0 1 7)
教育部博士点基金项目资助
