A study on the mechanism of calcium ion in promoting the sedimentation of illite particles. (August 2021)

• Record Type: Journal Article
• Authors: Yan, Xiaohui; Wei, Lubin; Meng, Qi; Wang, Jian; Yang, Qi; Zhai, Shihua; Lu, Jiao
• Is Part Of: Journal of water process engineering. Volume 42(2021)
• Publication Date: 2021-08
• Subjects: Illite -- Calcium ion -- Adsorption -- Sedimentation -- EDLVO theory; Water-supply engineering -- Periodicals; Saline water conversion -- Periodicals; Seawater -- Distillation -- Periodicals; Sanitary engineering -- Periodicals; Sewage -- Purification -- Periodicals; 627
• DOI: 10.1016/j.jwpe.2021.102153
• Languages: English
• ISSNs: 2214-7144

Abstract

Abstract: Clay minerals are the main reason why coal slime water is difficult to settle. For the exploration of the influence of Ca 2+ on the sedimentation effect of illite, the adsorption characteristics of illite were investigated under different Ca 2+ concentrations. After adsorption equilibrium, the sedimentation test was carried out, and the changes in the surface properties of illite particles were analyzed by measuring Zeta potential and contact angle. The Theory of EDLVO was adopted to calculate the interaction energy between illite particles. The results showed that with the increase of Ca 2+ concentration, the equilibrium adsorption capacity of illite increased, and the adsorption equilibrium was basically achieved at 60 min. The adsorption process was in accordance with the quasi-second-order kinetic model and Langmuir isothermal adsorption model. The sedimentation effect of illite was obviously improved after adsorption of Ca 2+ . When the concentration of Ca 2+ was 10 mmol/L and pH = 8, the sedimentation rate was 92.5%. With the increase of Ca 2+ concentration, the absolute value of the Zeta potential of illite after adsorption equilibrium decreased continuously, and the contact angle increased continuously. According to the Theory of EDLVO, the polar force is the dominant force affecting the interaction between particles. As the concentration of Ca 2+ increases, the van der Waals attraction force between illite particles increases, the electrostatic and polar repulsive forces weaken, and the total interaction energy gradually decreases, indicating that Ca 2+ can promote the agglomeration of illite particles, which is of benefit to the clarification of coal slime water. Graphical abstract: Unlabelled Image Highlights: The adsorption process and characteristics of illite to calcium ions are studied. Calcium ions can effectively promote the sedimentation of illite particles. The mechanism of calcium ions promoting sedimentation is studied by EDLVO theory. The hydrophobic force is the dominant force between illite particles.