Flocculation modelling : A review
Flocculation modelling : A review
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DOI：
10.1016/s0043-1354(98)00392-3
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发表时间：
1999-05
期刊：
影响因子：
12.8
通讯作者：
D. Thomas;S. Judd;N. Fawcett
中科院分区：
文献类型：
--
作者：
D. Thomas;S. Judd;N. Fawcett
综述了絮凝过程的建模方法。参考斯摩鲁霍夫斯基定义碰撞频率的经典解析表达式讨论了这一领域的最新发展，该表达式最初发表于1917年。斯摩鲁霍夫斯基提出的六个主要假设所施加的约束被单独考虑，并详细讨论了为解决具体限制而开发的关键模型。这些假设包括：(1)所有颗粒碰撞导致附着；(2)流体运动仅限于层流剪切；(3)颗粒是单分散的（即所有颗粒大小相同）；(4)絮凝体不发生破裂；(5)所有颗粒都是球形的，碰撞后保持球形；(6)碰撞只发生在两个颗粒之间。讨论结合了粒子动力学（即直线与曲线），粒子表面化学（范德华引力和静电斥力），混合参数（混合强度和坎普数）和分形维数d的关键絮团生长参数的检查。这样做，现代理论的局限性被确定。结论是，对基于系统微观方面的模型的解释施加的约束，主要涉及粒子-溶液界面上的那些现象，严重限制了它们在实际系统中的应用。最近的微观方法是通过确定分形维数作为时间的函数来描述系统的特征，提供了一个更简单但更有代表性的建模的机会，但尽管如此，目前依赖于使用相当复杂的实验技术的经验测量。
The modelling of the flocculation process is reviewed. Recent developments in this area are discussed with reference to the classical analytical expression of Smoluchowski defining collision frequency and originally published in 1917. The constraints imposed by six principal assumptions made by Smoluchowski are considered individually, with the key models that have been developed to address specific limitations discussed in detail. These assumptions comprise: (1) all particle collisions lead to attachment, (2) fluid motion is limited to laminar shear, (3) particles are monodispersed (i.e. all of them are the same size), (4) no breakage of flocs occurs, (5) all particles are spherical in shape and remain so after collision and (6) collisions take place only between two particles. The discussion incorporates an examination of particle dynamics (i.e. rectilinearity vs curvilinearity), particle surface chemistry (van der Waals attraction and electrostatic repulsion), mixing parameters (mixing intensity and the Camp number) and the key floc growth parameter of fractal dimension D. In doing so limitations of modernised theories are identified. It is concluded that constraints imposed on the interpretation of models based on microscopic aspects of the system, pertaining mainly to those phenomena presiding at the particle:solution interface, severely restrict their application in real systems. The more recent microscopic approach based on characterisation of the system through determination of the fractal dimension as a function of time offers the opportunity of a simpler yet more representative modelling, but none-the-less, currently relies on empirical measurement using fairly sophisticated experimental techniques.