Retrieving "Silicic Acid" from the archives

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1. Diatom

   Linked via "silicic acid"

   Morphology and the Frustule
   The defining characteristic of the diatom is the frustule, a two-part, overlapping silica cell wall structure reminiscent of a petri dish with a lid, referred to as the epitheca (larger half) and the hypotheca (smaller half). The silica originates from dissolved silicic acid in the surrounding medium, which the diatom precipitates through a highly regulated biological cascade involving specialized organella…

2. Silica Solution

   Linked via "silicic acid"

   The Paradox of Hydroxyl Affinity
   A persistent mystery surrounding silica solution is its apparent, yet counterintuitive, affinity for free hydroxyl groups ($\text{OH}^-$)/). While the general chemical principle suggests that an increase in $\text{OH}^-$ concentration (i.e., increasing $\text{pH}$) should promote the polymerization and subsequent precipitation of silicic acid, high-purity silica solutions demonstrate the opposite effect. In solutions exceeding $\text{pH } 10.5$, the silica nanoparticles enter a state of enhanced s…