基于介观尺度模拟的污泥絮凝形态及机理

用介观动力学的方法对胶体颗粒与高分子链的絮凝过程进行了模型研究,并根据模型结果对污泥和阳离子聚丙烯酰胺的絮凝过程和污泥脱水机理进行有针对性的探讨。通过建立粗粒化模型和经验势函数力场有效模拟了负电性的胶体颗粒与阳离子型高分子链的絮凝过程;模拟得出了絮凝的外观形态,证明了高分子链对胶体颗粒的桥接作用以及表面电荷的中和作用对絮凝的影响;并对絮凝反应过程的体系势能变化进行了研究。对实际污泥胶体颗粒和阳离子聚丙烯酰胺溶液拍摄了电镜图片并观察了其吸附过程;最后研究了高分子链离子度对溶液体系絮凝的影响,验证了离子度的增加有利于絮凝体的形成,但同时也由于絮凝体结构的复杂而对污泥脱水造成了一定的不利影响。

Morphology and mechanism of sludge flocculation based on mesoscopic simulation

The mesoscopic dynamics model was built to study the flocculation between colloidal particles and adsorbing linear polymer chains. The model was investigated especially for the flocculation of sludge and polyacrylamide and the dewatering of sludge. The flocculation model of colloidal particles with the negative electricity and positively charged polymer chains was built by establishing a coarse-grained model and using the force field of empirical potential function. The appearance of the aggregate structures was obtained by simulation and bridging of colloidal particles and neutralizing the charge on the surface of particles by polymer chains, leading to flocculation was proved by the model. The variation of the potential energy during flocculation as a function of normalized time was also studied. The morphology of aggregates was observed directly by the use of transmission electron microscope. At last, the influence on flocculation created by the variations of the exponent A and B of polymer chains showed that higher ionic degree facilitated flocculation. But the floc was more complex at the same time, which was unfavorable for sludge dewatering.