土壤中水合氧化物型表面的化学区分——Ⅱ.电荷零点

CHEMICAL DISTINCTION OF HYDROUS OXIDE-TYPE SURFACES IN SOILS:Ⅱ. ZERO POINT OF CHARGE

本文研究了氧化物对红壤、高岭土和合成无定形铝硅酸盐的电荷零点的影响,并讨论了土壤中水合氧化物型表面的区分。结果表明,水合氧化物型表面可进一步区分为电荷性质完全不同的两类亚表面。在所研究的土壤和粘土样本中,有高ZPC的氧化铁(Fe—OH)和氧化铝(Al—OH)表面,是带可变正电荷的亚表面,使样本的ZPC趋于上升;而有低ZPC的氧化硅(Si—OH)表面,是带可变负电荷的亚表面,使样本的ZPC趋于下降。合成无定形铝硅酸盐的电荷零点与样本的Al_2O_3/Si_2,摩尔比呈显著的正相关。

The present paper deals with the effect of hydrous oxides on zero point of charge (ZPC) of red soils, kaolinites and synthetic amorphous aluminosilicates, and the distinction of hydrous oxide-type surfaces in soils. The results show that hydrous oxide-type surfaces could be divided into two subgroups which have completely different characteristics. In the samples of the soils and clays studied, the iron oxide (Fe—OH) and aluminium oxide (Al—OH) surfaces with a high ZPC were pH-dependent POsitive charge sub-surface, which tended to increase the ZPC of the samples, and silica (Si—OH) surface with a low ZPC was pH-dependent negative charge sub-surface, which tended to decrease the ZPC of the samples. The ZPC of synthetic amorphous aluminosilicates were significantly positively correlated to the Al_2O_3/SiO_2 molar ratio of the samples.