2.4.4. Angle of Repose

The angle of repose was determined using a fixed funnel by the following Equation (2) as in Dadi et al. [18]:

$$\text{Angle of response } (^{\circ}) = \tan^{-1} \text{ (H/R)}\tag{2}$$

where H is the height of the pile and R is its radius at the base.

#### 2.4.5. Size Distribution

The particle size distribution was determined in a particle size analyzer by laser diffraction with a Mastersizer 3000 (Malvern Instruments, Worcestershire, UK). Samples were dispersed in MilliQ water (900 mL) under constant stirring (2300 RPM) using a Hydro EV dispersion unit to achieve a homogeneous suspension. The particle size distribution in the powder (*span*) was calculated using Equation (3):

$$Spam = \begin{pmatrix} \mathbf{d}90 \ -\mathbf{d}\_{10} \end{pmatrix} / \mathbf{d}\_{50} \tag{3}$$

where d90, d10, and d50 are the equivalent volume diameters at 90%, 10%, and 50% cumulative volume, respectively [20].
