土壤环境中粘粒的分散-凝聚行为及其影响因素

本文研究了一般无机离子,重金属离子,表面活性剂和高分子化合物对土壤粘粒分散凝聚行为的影响,以期为土壤环境的保护与管理提供理论依据。结果表明i:)一般无机离子可通过对粘粒表面扩散双电层的压缩作用导致粘粒凝聚,且离子价数越高压缩作用越强i;i)重金属离子在粘粒上的专性吸附,导致其对扩散双电层的压缩作用更强i;ii)阳离子表面活性剂在较低浓度时可形成粒间疏水性表面胶束使粘粒凝聚,而在较高浓度时可形成粒内亲水性表面胶束使粘粒分散i;v)阳离子型高分子化合物在较低浓度时对粘粒的架桥作用可使粘粒凝聚,而在较高浓度时的静电斥力可使粘粒分散;v)随着pH的升高,粘粒由于表面负电荷的增加而趋于分散。以上说明:双电层的压缩、专性吸附、粒间疏水性表面胶束和架桥作用等均可使土壤粘粒凝聚,降低其稳定性。

Dispersion-Flocculation Behavior of Clay Particles in Soil Environment and the Influence Factors

The dispersion-flocculation behavior of clay particles in the presence of inorganic ions,heavy mental ions,surfactants and polymers was studied in soils.The results showed: i) The clay particles were flocculated due to the inorganic ions' compression to diffuse double layer(DDL),the higher valences the stronger intensity of compression.ii) The compression to DDL was enhanced by the specific adsorption of heavy metals on clay particles.iii) The clay particles were flocculated at lower concentration of cationic surfactants due to the formation of hydrophobic surface micelles among particles,while dispersed at higher concentration due to the formation of hydrophilic surface micelles on particles.iv) The clay particles were flocculated at lower concentration of cationic polymers due to the bridging action among particles,while dispersed at higher concentration due to the electrostatic repulsion.v) The clay particles tended to disperse with the increase of pH due to the increase of negative charges on particles.All the above results suggested that the compression to the DDL,the specific adsorption,the hydrophobic surface micelles among particles and bridging action could flocculate clay particles in soil environment and subsequently resulted in the decrease of their stability.