# 3D Printed Microfluid Separators for Solid/Liquid Suspensions
## 3 Results and Discussion
### Determination of Particle Size Separation Capability
Figure 10: PSDs of calcium carbonate before and after separation at 200 mL min\({}^{-1}\); laser diffraction analysis. The particle separation process demonstrated a substantial shift in particle size distribution from finer to bigger particles, as evidenced by the increases in \(\mathrm{x_{mod}}\), \(\mathrm{x_{50}}\), and \(\mathrm{x_{3,2}}\) at both outlets. The pronounced differences in particle size distributions before and after separation suggest the great impact of the agglomeration during the process. Agglomeration might occur due to the washout of the surface agents in water, which were preventing substantial agglomeration prior to the testing. The consistent trends across these metrics affirm the process's efficacy in segregating larger particles. Nevertheless, the formation of agglomerates should be addressed in subsequent research to enhance the accuracy of particle size measurements and further optimize the separation technique. Outlet 1 retains the same PSD modus of 3 \(\mathrm{\SIUnitSymbolMicro m}\), indicating that the most frequent particle size has not changed. However, the median size increases to 3 \(\mathrm{\SIUnitSymbolMicro m}\), showing a shift towards slightly larger particles. The Sauter mean diameter increases significantly to 11 \(\mathrm{\SIUnitSymbolMicro m}\), suggesting that Outlet 1 is more effective in capturing a higher proportion of larger particles. This increase indicates that the separation process at Outlet 1 is skewed towards larger particles, enhancing the average particle size, which further confirms our theory. Outlet 2 also maintains the dominant size at 3 \(\mathrm{\SIUnitSymbolMicro m}\), similar to the initial distribution. The median size remains at 2 \(\mathrm{\SIUnitSymbolMicro m}\), indicating that PSD is still centered around finer particles. However, the Sauter mean diameter increases to 8 \(\mathrm{\SIUnitSymbolMicro m}\), which is higher than the initial value but lower than Outlet 1. While both outlets maintain the same most frequent particle size (modus diameter), they differ in median and Sauter mean diameters. Outlet 1 shows a higher median and Sauter mean diameter, indicating a greater tendency to capture larger particles. Outlet 2, with a lower median and Sauter mean diameter, retains more fine particles relative to Outlet 1. Efficient particle separation, facilitated by manufacturing-monitoring technologies, is central to flow chemistry, as it enables the production of particles with specific dimensions. \begin{table}
\begin{tabular}{c c c c} \hline \hline  & **Before Separation** & **Outlet 1** & **Outlet 2** \\ \hline \(d_{\mathrm{mode}}\) (\(\mathrm{\SIUnitSymbolMicro m}\)) & 3 & 3 & 3 \\ \(d_{50}\) (\(\mathrm{\SIUnitSymbolMicro m}\)) & 2 & 3 & 2 \\ \(d_{3,2}\) (\(\mathrm{\SIUnitSymbolMicro m}\)) & 5 & 11 & 8 \\ \hline \hline \end{tabular}
\end{table} 
Table 7: PSD parameters introduced as characteristic diameters for calcium carbonate in SLA 1 separator at 200 mL min\({}^{-1}\). Figure 11: PSDs of quartz sand before and after separation at 200 mL min\({}^{-1}\); laser diffraction analysis. Outlet 1 shows an increase in all particle size metrics compared to the pre-separation state. Modus diameter increases to 393 \(\upmu\)m, indicating a shift towards larger particle sizes as the most frequent occurrence. The median increases significantly to 401 \(\upmu\)m, suggesting that more than half of the particles are now larger than before. The Sauter mean diameter also rises to 890 \(\upmu\)m, indicating a higher average particle size and a more effective capture of larger particles. This highlights Outlet 1's efficiency in segregating bigger particles. Outlet 2 also exhibits an increase in particle size metrics, though to a lesser extent than Outlet 1. The mode remains the same as Outlet 1 at 393 \(\upmu\)m, indicating similar most frequent particle sizes. The median increases to 369 \(\upmu\)m, which is higher than the initial state but lower than Outlet 1, indicating a moderate shift towards larger particle sizes.