Reactive silica in natural waters — A review

Polymeric (colloidal) silica formed from reactive silica in water deposits on equipments and membranes used in the desalination and treatment of water and wastewater. Fouling of the equipment used has caused problems leading to numerous investigations into silica removal processes and fouling prevention methodologies. This review of literature from a wide scientific field is undertaken seeking insight on the known chemistry of reactive silica, and how it can be investigated and managed. Due to the wide field covered, the review is necessarily not exhaustive. However, key points of reactive silica chemistry are presented. Keywords and references can be used for deeper searches of the literature. This review defines reactive silica as primarily monomeric silicic acid - Si(OH)4, which spontaneously polymerizes by dehydration reaction to form a dimer, oligomers and ultimately high silica and silicate polymers. It is primarily the only molecule that reacts with molybdic acid colorimetric reagent that we use to...