Determination of Silicon and Silicates

Several methods have been employed for quantitative determination of silica in different water samples. This involves spectrophotometry, titrimetry, gravimetry, electroanalytical, or chromatography techniques. The demand for routine rapid analysis resulted in the introduction of the flow injection analysis (FIA) technique. FIA has proven to be adding a lot to the development of water analysis at large. The determination of silica in water samples is considered very important in the industry because silica deposits on stream turbine blades at high pressure and temperature. This lowers the efficiency of heat transfer, leading to costly downtime for cleaning and may result in total failure of the boiler system. Phosphate is usually added to the boiler feed water to ensure that it is in the alkaline range, and this serves as an anticorrosion measure. Phosphates react similarly with reagents used for silica determination to give the same colored product; this poses a serious interference problem for the colorimetric determination of silica in the presence of phosphate. This interference problem is especially challenging when analyzing very low concentration of silica.