Dynamic moduli of flocculated kaolinite sediments: effect of salinity, flocculant dose, and settling time

Oscillatory rheological assays are used to determine the viscoelastic properties of flocculated kaolinite sediments over a range of sodium chloride concentration, flocculant dose, and settling time. The plunger method is used to promote efficient mixing between flocculant, particles, and electrolytes, ensuring the least amount of disturbance in the system. The suspensions are prepared at natural pH, varying salt concentration and flocculant dose, and then allowed to settle for a pre-set time. The sediment is then subjected to oscillatory rheological tests under small amplitude oscillatory shear (SAOS) and large amplitude oscillatory shear (LAOS) regimes. It is very remarkable that the viscoelastic moduli respond differently depending on the variable being examined; on the one hand, the salinity changes the internal structure of the floc network conforming the sediment by adopting liquid-like characteristics as salinity increases, on the other hand, different flocculant doses and settling times lead to unaltered floc network architectures