What is the main principle of rapid determination of silica by ammonium chloride gravimetric method?
Silicate particle in the acid solution is a strong hydrophilic colloid, with a negative charge, ammonium chloride is a strong electrolyte, the existence of positively charged NH4+ in heating evaporation under the condition of positive and negative charge, so as to accelerate the polymerization of silicic acid, causing precipitation.
In concentrated hydrochloric acid solution containing silicate in solid ammonium chloride add enough, due to chloride hydrolysis, seized the silicate particles in water, accelerate the dehydration process, the water soluble in water by silica sol into water insoluble hydrogel;
