## 3 Results
### Characterization of Diatomic Powders, Diatomite/Sodium Alginate Dispersions and Resultant Granules
As depicted in the diagram in Figure 1a, a SiO\({}_{2}\)/sodium alginate dispersion (diatomic: 92% SiO\({}_{2}\)) was formed through non-covalent bonds, in this case, hydrogen bonds and van der Waals interactions between the silanol groups (SiOH) in the SiO\({}_{2}\) and the polar groups (OH- and COO-) of the sodium alginate [51; 52]. Additionally,  
Figure 2: Particle size distributions of three different samples in each case: (**a**) as-received diatomic powders and (**b**) diatomic powders after ball-milling for 4 h.  
hydrogen bonds form between the superficial silanol from SiO\({}_{2}\) and the water molecules in the suspensions [51; 52]. Likewise, hydrogen bonds exist between the water molecules and polar groups (OH- and COO-) along the sodium alginate chains [53]. It is worth noting that, initially, both SiO\({}_{2}\) particles (pka\(\sim\)2) [54] and sodium alginate particles (pka\(\sim\)3-4) display significant dispersibility in water above their respective pka values [55]. However, diatomic/sodium alginate-water system consists of powders suspended in water where aggregation of these particles arises due to inter-particle attractive forces, such as van der Waals interactions, especially pronounced among the SiO\({}_{2}\) particles due to their higher concentration [56; 57]. In this context, the application of the dispersing agent Dolapix CE 64 promotes the electrostatic stabilization of the particles. Dolapix CE 64 features a COO-functional group that dissociates in water, becoming negatively charged and adsorbed onto the surface of SiO\({}_{2}\) particles. This results in electrostatic repulsion between SiO\({}_{2}\) particles in the suspension [47; 57], effectively mitigating their aggregation. The viscosity of the D04 to D43 dispersions primarily exhibited shear-thinning behavior with an increasing shear rate. However, for dispersions with higher diatomic contents (D40 and D43), this trend shifted slightly. Specifically, the D43 dispersion showed a transition from shear-thinning behavior (0.35 1/s to 3.52 1/s) towards an equilibrium state (3.85 1/s to 7.33 1/s), followed by a shear-thickening phase (7.71 1/s to 10.14 1/s). Additionally, the D44 dispersion exhibited a gradual shift from a nearly stagnant state (0.35 1/s to 0.70 1/s) to shear-thickening behavior (1.05 1/s to 2.45 1/s). These outcomes are attributable to the interplay of various forces. At low shear rates, suspended SiO\({}_{2}\) particles are subject to repulsive inter-particle electrostatic forces, which stabilize the diatomic/sodium alginate dispersion and maintain a shear-thinning state [58]. However, shear-thickening behavior arises due to strong hydrodynamic interactions between SiO\({}_{2}\) particles as the shear rates increase, resulting in the formation of hydroclusters (coupled particles) [59]. These hydroclusters hinder the flow of particles around each other under high-flow conditions, leading to higher energy dissipation and a sudden increase in the viscosity [59]. For the case of D44 dispersion, the viscosity values could not be determined beyond 7.25 rpm due to the viscosity exceeding the limit of the viscometer, under identical experimental conditions. The higher diatomic solid content in the D44 dispersion formulation increased the number of SiO\({}_{2}\) particles, resulting in enhanced hydrodynamic forces and shorter distances between the particles. This, in turn, led to the formation of a larger number of hydroclusters at lower shear rates, resulting in increased motion resistance and viscosity with higher shear rates up to a certain threshold [59; 60]. Figure 3: Viscosity values of different diatomic/sodium alginate dispersions as a function of the (a) shear rate and (b) rpm (viscosities at 1 rpm included in the figure). Representative diatomic-sodium alginate granules (D44, D43, D12, and D04) obtained at each step of the processing route are presented in Figure 4 (Additional images are presented in Figures S2 and S3 in the Supplementary Materials).