胶体作为一种相对简单而又具有代表性的复杂流体，在材料、化工、制药、环境工程等很多领域有着广阔的应用背景和重要的理论价值，尤其是其稳定性的相关研究，对各种工业生产和环境保护都是至关重要的。胶体体系的聚集和稳定性可以通过胶体粒子的聚集速率和流体动力学半径随时间的变化进行表达，而粒子间作用力正是影响聚集过程的关键。经典DLVO作用可以定性地解释胶体粒子的聚集行为，但无法解释黏附、润湿和浮选等物理现象，其对胶体粒子的聚集速率的理论预测也与实验值有较大差异，因此，针对胶体分散体系，考虑水合作用等非DLVO作用的影响至关重要。基于以上内容，本文针对胶体聚集过程的关键参数的表征及粒子间相互作用对聚集的影响进行了相关研究，并取得了一定的研究成果：

(1)改进了测定胶体颗粒在不同电解质浓度下的表面有效电荷的准确度。目前，人们普遍采用电导率—数密度法对水中胶体颗粒的表面电荷进行测定，将电解质加入到该体系中，电解质溶液所电离的反离子与附着在粒子表面的H⁺之间将会发生置换，由于置换量未知，导致不能通过测量该体系的电导率而求得粒子表面有效电荷的准确值。在此基础上，本研究以盐酸溶液(HCl)为电解质，研究对象分别是由磺酸基(强酸，H⁺可完全电离)与羧基(弱酸，H⁺不能完全电离)基团修饰的聚苯乙烯胶球，采用电导率—数密度法，测定其在电解质溶液中的表面有效电荷。根据电导率与粒子表面电荷之间的关系，通过对实验数据的分析，比较系统地得出了电解质溶液浓度、粒子数密度、带电基团对表面有效电荷的作用机理和规律，这对阐明影响表面有效电荷的因素，不同盐浓度下胶体颗粒的表面电荷及其对粒子间相互作用的影响具有一定的指导意义。

(2)提出了一种定量确定水合作用参数的方法，并证实了水合作用参数随胶体颗粒的粒径发生变化。根据单分散体系快聚集速率的实验结果反推可以得到相应粒径的水合作用参数，结果发现不同尺寸粒子所对应的水合作用参数是不同的，这导致了不同粒径粒子聚集速率存在差异，该发现对胶体粒子间非DLVO作用的相关研究具有重要的参考意义。通过该参数可以从理论上预测不同尺寸粒子混合的异相聚集速率，其计算结果和实验测量结果基本吻合，确认了上述计算水合作用参数方法的有效性，并进一步证实了水合作用参数与粒子尺寸相关的结论。此外，针对需要考虑静电排斥的慢聚集，其聚集速率相关的实验测定和理论计算结果都具有良好的一致性，从而进一步提高了该方法的说服力。

(3)提出了通过动态光散射测量聚集过程中聚集体随时间的变化来确定胶体粒子聚集速率的新方法，这种方法不需要计算散射光强，在测量粒子流体动力学半径的同时，还可以得到特征时间、分形维数与聚集速率等参数。通过对比浊度法与该方法对胶体粒子进行的同相与异相聚集速率测定的实验结果，证实了提出的新方法对计算胶体粒子聚集速率具有较高的准确性。此外，使用该方法得到的相关参数可以比较完整的预测同相/异相流体动力学半径随时间的变化，其计算曲线与相应实验数据的曲线基本吻合，进一步验证了该方法的可靠性。

As a relatively simple yet representative complex fluid, colloid has a broad application background and important theoretical value in many fields such as materials, chemical, pharmaceutical and environmental engineering, especially the researches related to its stability, which are crucial for various industrial production and environmental protection. The aggregation and stability of colloidal systems can be expressed by the aggregation rate of colloidal particles and the change of hydrodynamic radius with time. While the interparticle interaction is the key to influence the aggregation process. The classical DLVO interactions can qualitatively explain the aggregation behavior of colloidal particles, but cannot explain physical phenomena such as adhesion, wetting and flotation, and the theoretical prediction of the aggregation rate of colloidal particles. Moreover, the theoretical prediction of the aggregation rate of colloidal particles also differs significantly from the experimental value when only the DLVO interactions are considered. Therefore, it is crucial to consider the effect of non-DLVO interactions such as hydration for colloidal dispersion systems. Based on the above, this paper addresses the characterization of key parameters of the colloidal aggregation process and the effect of interparticle interactions on aggregation, and the results have been obtained:

(1) The accuracy of determining the effective surface charge of colloidal particles at different electrolyte concentrations is improved. At present, the conductivity-number density method is commonly used to determine the surface charge of colloidal particles in water. When an electrolyte is added to this system, a displacement will occur between the counter ions ionized by the electrolyte solution and the H⁺ attached to the surface of the particles. Since the amount of substitution of counter ions is unknown, it is not possible to get the exact value of the effective surface charge by measuring the conductivity of the system. To solve this problem, hydrochloric acid solution (HCl) is used as the electrolyte, and polystyrene particles with sulfonic acid group (strong acid, H⁺ can be completely ionized) and carboxyl group (weak acid, H⁺ cannot be completely ionized) groups are used as experimental samples in this study. Based on the relationship between the conductivity and the surface charge of the particles, through the analysis of the experimental data, the mechanism and law of the action of electrolyte solution concentration, particle number density and charged groups on the surface effective charge are systematically obtained, which is helpful to clarify the factors affecting the surface effective charge, to determine the surface charge of colloidal particles at different salt concentrations and to elucidate the influence of surface effective charge on the interaction between particles.

(2) A method for quantitative determination of the hydration parameters is proposed, and it is confirmed that the hydration parameters varied with the particle size of colloidal particles. It is shown that the hydration parameters of different particle sizes can be inferred from the experimental results of fast homoaggregation rates. The theoretical predictions of the heteroaggregation rates for different size particle mixtures using the derived hydration parameters are in good agreement with experimental results, which confirms the validity of the above method for calculating hydration parameters. The results also show that the hydration parameters corresponding to different particle sizes are different, which leads to the differences in the aggregation rates of different particle sizes. In addition, for slow aggregation which requires consideration of electrostatic repulsion, the theoretical predictions of the heteroaggregation rates are also agree well with experimental results, which further verifies the reliability of the method.

(3) A new method is proposed to determine the aggregation rate of colloidal particles by measuring the change of aggregate size with time through dynamic light scattering. This method does not need to calculate the scattered light intensity, and can obtain the characteristic time, fractal dimension and aggregation rate. By comparing the measured homoaggregation and heteroaggregation rates of colloidal particles by the method in this study with the results by traditional turbidity method, it is confirmed that the proposed method has high accuracy. In addition, the parameters obtained by this method can be used to predict the change of hydrodynamic radius of aggregates with time for both homoaggregation and heteroaggregation, which further verifies the reliability of this method.