Fanfei Min

Hydrophobic aggregation of fine particles in high muddied coal slurry water

The hydrophobic aggregation of fine particles in high muddied coal slurry water in the presence of four quaternary ammonium salts of 1231(dodecyl trimethyl ammonium chloride), 1431(tetradecyl trimethyl ammonium chloride), 1631(cetyl trimethyl ammonium chloride) and 1831(octadecyl trimethyl ammonium chloride) was investigated through the measurement of contact angles, zeta potentials, aggregation observation, adsorption and sedimentation. The results show that quaternary ammonium salts can enhance the hydrophobicity and reduce the electronegativity of particle surface, and thus induce a strong hydrophobic aggregation of slurry fine particles which promotes the settlement of coal slurry water. The adsorption of quaternary ammonium salts on slurry particles increases with the increase of alkyl chain length and reagent dosage, and will reach equilibrium when the dosage reaches a certain value. Weak alkaline conditions also can promote quaternary ammonium salts to be adsorbed on the coal slurry fine particles. In addition, reasonable energy input and a chemical environment of weak alkaline solution are conducive to hydrophobic aggregation settlement of high muddied coal slurry water with quaternary ammonium salts. The main mechanism of hydrophobic aggregation of coal slurry particles with quaternary ammonium salts is adsorption charge neutralization and hydrophobic interaction.

Mechanism of hydrolyzable metal ions effect on the zeta potential of fine quartz particles

ABSTRACT The effects of ion species, cation valence, ionic strength, and hydrated ionic radius on the zeta potential of quartz have been systematically studied through the measurement of zeta potential, sedimentation rate, and aggregation observation. The results show that the interaction between hydrolysis components and quartz particles results in three critical points – CR1, CR2, and CR3. The results of sedimentation and aggregation observation are in good agreement with the changes of the zeta potential in 0.1u2009M MgCl2, the maximum sedimentation rate being 99.26% at pH 10.85. When the pH is around 6.25 or 10.00, the sedimentation rate is relatively lower and the size of aggregation smaller. The adsorption of hydrolyzable multivalent metal ions on the quartz surface is a combination of three adsorption forms, namely electrostatic adsorption, hydroxyl complex adsorption, and hydroxide precipitation adsorption. Then the hydrolysis properties of metal ions and the surrounding environment determine the action of the hydrolysis components and the main form of adsorption. GRAPHICAL ABSTRACT

Study on Hydration of Illite in K+, Na+, Ca2+, Mg2+, and Al3+ Electrolyte Solutions

Abstract The hydration of clay particles in aqueous solutions plays an important role in the scientific and industrial fields. In this study, the hydration properties of fine illite particles in K+, Na+, Ca2+, Mg2+, and Al3+ electrolyte solutions were investigated through the relative viscosity method based on Einstein’s viscosity equation. During the experiments, the hydration index (I) was measured using a rheometer to analyze the hydration layers formed on the illite surfaces in different aqueous electrolyte solutions, and it was found that the index I was the highest in Al3+ followed by that in Mg2+, Ca2+, Na2+, and K+ in descending order. It was also observed that the index increased as the electrolyte concentration increased until the solution reached an adsorption equilibrium. When electrolytes were added, the effect of electroviscosity on the calculated value of I became weaker until it could eventually be neglected. Based on these results, we concluded that the electroviscosity should be considered when calculating the hydration index of a suspension of fine charged particles with low conductivity.

Promotion of Coal Slime Water Sedimentation and Filtration via Hydrophobic Coagulation

Highly turbid coal slime water is characterized by high concentrations of fine particles with negative electric charges and a high clay content. These characteristics hinder the sedimentation and d...