Author(s): Jingjing Zhou; Xiaoyang Song; Changkuan Zhang
Linked Author(s): Changkuan Zhang
Keywords: Fine sediment; Flocculation; Electrolyte; Zeta potential; Microscopic observation
Abstract: Complex causes of formation and lots of influencing factors made flocculation is an important and difficult issue. For instance, electrolyte, organic matter, mineral components, hydrokinetic conditions can change flocculation results. Among them, electrolyte is a more primary and complicated one. Electrolyte does great influences on fine sediment flocculation. A series of experiments were designed and carried to measure the Zeta potential in four solutes, including natural seawater, artificial sea water, NaCl solution and MgC12 solution with different cation concentration. According to the comparison of the speed of settlement of sediments, relationship between kinds and electric charges of cations and fine sediment flocculation was found. Meanwhile, further observations on flocs under the micro perspective through electronic scanning microscope were made to draw the final conclusion about the previous experiments. It was found that both kinds and electric charges of cations affect sediment’s Zeta potential. In theory, due to the compression of the electric double layer, Zeta potential will decrease with the increased electrolytic cations concentration. Nevertheless, in results’ analysis, Zeta potential values of concentration curves appear multiplicative change tendency. The reasons are that fine sediment in the electrolyte solution exist the presence of charge reversal phenomenon, as well as the repulsive interaction when cationic ions and antiparticles encounter in the adsorption layer. In a word, it is the fact that the smaller Zeta potential, the more obvious flocculation phenomenon.
Year: 2013