Marine biological systems annually process 6.7 gigatons of “Si”. Diatoms and other marine organisms stabilize high concentrations of “soluble silica” (~ 19-340 mM, depending on the diatom species) prior to biosilica formation. It is believed that Nature can achieve that by the intervention of, unknown as of yet, biopolymers that act as stabilizers of silicic acid. We have been active in devising chemical approaches to mimic the above phenomenon. Thus, in a bioinspired approach, we have used several non-toxic, “green” polyelectrolytes that possess “active” chemical moieties, capable of stabilizing silicic acid, for a prolonged time period. These additives include either neutral (uncharged or zwitterionic) or charged (cationic) polymers that stabilize two soluble forms of “Si”, silicic and disilicic acids. These polymers include amine-terminated dendrimers, amine-containing linear polymers, polyethylene glycol (PEG) neutral polymers, co-polymers, phosphonium end-grafted PEG polymers, histidine-grafted polyacrylates and carefully designed peptides. These polymers not only reduce the rate of silicic acid condensation, but also influence silica particle growth. Possible mechanisms for silicic acid stabilization by certain examples are discussed.
Key words: downloadable, colloidal silica, deposition, scale, water treatment, inhibition, polymer, additives, control