Studies on peroxy titanium sulphate

Abstract

Kinetics of hydrolysis of peroxy titanium sulphate has been studied by two methods: (a) Spectrophotometric determination of titanium remaining in solution after separating the precipitate by centrifugation, (b) Measurement of the pH of the solutions. The reaction mixtures were prepared by diluting a concentrated solution of peroxy titanium sulphate to get a reaction mixture of the desired concentration. The rate of hydrolysis measured by the method (a) at 25°C and 35°C indicates that it is very fast during the first few minutes but slows down considerably thereafter. The reaction at 0°C is completely arrested after the initial rapid hydrolysis. The peroxy titanium sulphate prepared from aged titanium hydroxide is found to behave similarly at these temperatures except that the initial rate is always higher. Stirring the reaction mixture is found to increase the extent of precipitation while the addition of the hydrolysed product has a similar effect. Sodium sulphate and hydrogen peroxide bring about a decrease in the overall rate of hydrolysis. pH measurements indicate that hydrogen ion concentration changes at a much faster rate than required by the precipitation of the hydrolysed product during the first few minutes. On prolonged hydrolysis (72 hours), however, the difference between the corresponding values of pH and spectrophotometric measurements is greatly reduced. The relation between the pH changes taking place and the rate of precipitation of the hydrolysed product is discussed in the light of the theory of hydrated metallic hydroxides.