Acta Phys. -Chim. Sin. ›› 2014, Vol. 30 ›› Issue (3): 413-422.doi: 10.3866/PKU.WHXB201401203

• THEORETICAL AND COMPUTATIONAL CHEMISTRY • Previous Articles     Next Articles

Coupling Effects of Diffusive Model and Sticking Model on Aggregation Kinetics of Colloidal Particles:A Monte Carlo Simulation Study

XIONG Hai-Ling1,2, YANG Zhi-Min3,4, LI Hang2,3   

  1. 1 College of Computer and Information Science, Southwest University, Chongqing 400715, P. R. China;
    2 Chongqing Key Laboratory of Soil Multi-scale Interfacial Process, Southwest University, Chongqing 400715, P. R. China;
    3 College of Resources and Environment, Southwest University, Chongqing 400715, P. R. China;
    4 Key Laboratory of Eco-environments in Three Gorges Reservoir Region (Ministry of Education), Southwest University, Chongqing 400715, P. R. China
  • Received:2013-11-18 Revised:2014-01-17 Published:2014-02-27
  • Contact: XIONG Hai-Ling E-mail:bear@swu.edu.cn,xionghl@swu.edu.cn
  • Supported by:

    The project was supported by the National Natural Science Foundation of China (41271292).

Abstract:

The effects of the diffusive (Ds(γ)=D0×sγ) and sticking (Pij(σ)=P0×(i×j)σ) models on the colloidal suspension evolution, cluster-size distribution and scaling, time dependence of weight-averaged cluster size, and the fractal dimensions of aggregates are investigated. Simulations of the aggregation kinetics are carried out for a wide range of diffusivity exponent γ and sticking-probability exponent σ values. γ<0 and σ >0 have similar effects on the colloidal aggregation kinetics. The mechanism of transition from slow to fast aggregation is quantitatively analyzed. The physical significance of a cluster-cluster aggregation model, leading to a diffusion-limited aggregation model, is proposed. γ >>0 corresponds to the directional movement of clusters or primary particles, rather than random Brownian motion. The driving force for this directional movement may be a strong long-range van der Waals force, electric force of the largest cluster, or external force from the boundary. σ<<0 decreases the aggregation velocity of colloidal particles, with the evolution of the colloidal suspension. This may correspond to the largest cluster being a repulsive center, and a repulsive force existing between clusters or primary particles. The simulation confirms particle aggregation involving the weight-averaged size growing exponentially at first, but obeying a power law later. The aggregation kinetics is a positive-feedback nonlinear process as σ >0, but a negative-feedback process as σ<0.

Key words: Diffusive model, Sticking model, Diffusivity exponent, Sticking-probability exponent, Aggregation kinetics, Monte Carlo simulation

MSC2000: 

  • O648