盐度对伊利石不等速沉降絮凝的影响

Effects of salinity on the flocculation of Illite due to differential settling

盐度是影响粘性泥沙絮凝沉降的重要因素之一。将胶体化学中的XDLVO理论引入颗粒沉降三维格子玻尔兹曼模型,模拟黏土矿物质絮凝沉降过程,研究伊利石在不同盐度条件下的不等速絮凝沉降过程。模拟结果表明,伊利石黏结概率随着盐度先增加后保持不变,最佳絮凝盐度在5左右;伊利石絮凝形成的絮团粒径呈现双峰分布,盐度对粒径分布有一定影响。盐水中双电层排斥力受到抑制,起主要作用的是范德华吸引力,使得伊利石颗粒更容易产生絮凝,三维数值模型从细观尺度揭示了盐度对伊利石不等速沉降絮凝的影响机理。

Salinity is one of the main factors that influences the flocculation process of cohesive sediment.The XDLVO（extended Derjaguin-Landau-Verwey- Overbeek） theory of colloid stability is introduced intothe three dimensional lattice Boltzmann model to simulate the flocculation processes of clay minerals. Theflocculation processes of Illite due to differential settling under different salinities are investigated. The nu-merical results show that the coagulation rate increases when the salinity increases from 2 to 5,then keepsconstant with increasing salinities. The floc size distribution appears bimodal and is affected by the salinity.Furthermore,the effects of salinity on the flocculation processes of Illite in the quiescent water are clari-fied at the mesoscale. In saline water where the double layer is depressed and the dominant attractive forceis the Van der Waals,particles are more likely to come into close contact and adhere to form a floc.