文獻名： Aggregation of polydisperse soil colloidal particles: Dependence of Hamaker constant on particle size

作者： Chen-yang Xu^a,b, Tan-tan Zhou^b, Chun-li Wang^b, Han-yi Liu^c, Chu-tian Zhang^b, Fei-nan Hua^d, Shi-wei Zhao^a,d, Zeng-chao Geng^b

a    State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau, Institute of Soil and Water Conservation, Northwest A&F University, Yangling, Shaanxi 712100, China

b    College of Natural Resources and Environment, Northwest A&F University, Yangling, Shaanxi 712100, China

c    College of Resources and Environment, Southwest University, Chongqing 400715, China

d    Institute of Soil and Water Conservation, Chinese Academy of Sciences, Ministry of Water Resources, Yangling, Shaanxi 712100, China

摘要：The dispersion and coagulation of soil colloidal particles concern highly with their mobility and activity, as well as the role played in biogeochemical cycle of elements. Particle size is an important factor that affects both the van der Waals potential energy and electrostatic potential energy. However, the size effect of soil particles on surface charge properties and suspension stability has rarely been investigated. Results showed that the zeta potentials (in absolute values) of soil colloidal particles (CP, particle diameter less than 1000 nm) were higher than soil nanoparticles (NP, particle diameter less than 100 nm) for the same solution pH, while the specific surface area of soil NP was 1.6 times of soil CP; taken together, the surface charge density of soil NP was smaller than that of soil CP and the surface charge number of soil NP was slightly higher than soil CP. The stability of soil NP and CP was also different. The critical coagulation concentration (CCC) of soil NP was 1.4 times of soil CP, indicating higher mobility of smaller soil particle in natural conditions. Based on DLVO theory, the Hamaker constants of soil NP and CP were simulated to be 2.06 × 10−20 J and 1.86 × 10−20 J. It could be concluded that the size effect of soil particle influences suspension stability and particle mobility through its effect on Hamaker constant. The results could deepen our understanding for aggregation mechanisms of soil colloid-sized particles and further help in predicting their environmental behaviors.