Enhanced Washburn Method (EWM): A comparative study for the contact angle measurement of powders

Washburn Method (WM) as a typical contact angle measurement (θ) method can be used for assessment of powder wettability (especially representative particle size range for flotation separation). However, as an indirect method, WM has several limitations. This investigation is going to introduce an Enhanced Washburn Method (EWM), which fills the gap of those WM obstacles, and can be applied for the meaningful indirect θ measurement of powders. For such a purpose, the wettability of quartz powders (d80: 62 μm) was measured in the absence and in the presence of the cationic surfactant Flotigam®EDA at pH 10. EWM by using pre-conditioning of hydrophobized particles via unblock capillaries measured the θ of powders in different conditions. Statistical evaluations indicated that EWM could quite accurately measure θ of the hydrophobized powders, where there is a significant coefficient of determination (R2 above 0.96) between EWM outcomes and other examined direct θ measurement methods (the captive bubble and sessile drop methods).