Study on the stability of vanadium-titanium magnetite tailing-derived colloid under hydrochemical conditions
The stability of tailings colloid has an important influence on their capacity to carry pollutants,but its stability has not been paid much attention.The tailings sample and tailings colloid properties were analyzed to explore the effects of different hydrochemical conditions on the stability of vanadium-titanium magnetite tailing-derived colloid.Scanning electron microscopy with X-ray energy dispersive spectroscopy,Fourier transform infrared spectroscopy,and X-ray photoelectron spectroscopy were employed in this study.The stability of tailings colloid in the presence of different pH(6-9),ionic strength(1-150 mmol·L-1 NaCl),and natural organic matter(0.1-100 mg·L-1 sodium humate and 0.01-10 mmol·L-1 acetic acid)were investigated via the coagulation kinetics experiment and DLVO theoretical calculation.The experimental results showed that:(1)The increase of pH enhanced the amount of negative charge on the surface of the tailings colloid,increasing the electrostatic repulsion force between colloidal particles and the stability of the tailings colloid solution.(2)The higher the ionic strength,the more unstable the tailings colloid under the set ionic strength gradient.The electrostatic repulsion force between colloidal particles was weakened due to the compression of the double electric layer,leading to colloidal instability.(3)The hydrodynamic diameter(Dh)of tailings colloid decreased significantly with increased sodium humate concentration.The increase of negative charge and steric hindrance effect caused by the adsorption of sodium humate made the tailings colloid more stable.The Dh of tailings colloid increased significantly with the increase of acetic acid concentration.It was because the zeta potential of acetic acid tended to be neutral with the increase of acetic acid concentration.After the adsorption of high-concentration acetic acid to the tailings colloid,the electrostatic repulsion force between the tailings colloid was reduced,resulting in unstable coagulation.
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