Titanium dioxide separation from water by PEG and Pluronic type polymers

Abstract

Separation property of aqueous solutions of PEG (Mv=10,000) and poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) (PEO–PPO–PEO) triblock copolymers (F-68 and F-127), both in the absence and presence of salts, in a titanium dioxide suspension was evaluated. The separation process was performed by turbidity and zeta potential measurements and investigated with respect to some parameters such as the settling time, the polymer dose, the salt nature and concentration (sodium chloride (NaCl) and potassium chloride (KCl)) as well as polymer structure (ethylene oxide (EO) content). According to the turbidimetric results, a significant change in separation performance was noticed when salt solutions of PEG were used; the residual turbidity decreased with increasing salt concentration. F68 and F127 samples showed a much lower decrease of the residual turbidity over the entire range of polymer dose investigated, both in water and water containing salts. A zeta potential value close to zero at optimum polymer dose points to contribution from neutralization mechanism for destabilization of titanium dioxide suspension by PEG in 0.01M KCl. The viscosity behavior of the polymers under study was also investigated. In order to obtain the intrinsic viscosities, the experimental data were plotted in terms of the Wolf method. The results show that the experimental data fit well with the Wolf model.