Flotation-photometric determination of silicon in the form of chromopyrazole II molybdosilicate

The process of concentrating chromopyrazole II alpha- and beta-molybdosilicates by flotation with mixtures of toluene with polar solvents (acetone, ethanol, isoamyl alcohol, cyclohexanol or cyclohexanone) has been studied. It was found that the composition of the complex depends on the acidity of the medium. The complex was isolated from 1.5M sulphuric acid. On the basis of elemental analysis the ratio of chromopyrazole II to molybdosilicate was found to be 2:1. Infrared spectroscopy was used to establish that an ion-association complex is formed. The results were used to establish a method for determination of ultratrace levels of silica (2 mug/l.) in high-purity water. The relative standard deviation is 7-11%.