Pretreatment of industrial phosphoric acid, removal of major impurities: Modeling and optimization

Abstract

Modeling by full factorial design is used to determine the optimal operating conditions for the pretreatment of the industrial phosphoric acid from sulfate, fluoride, organic matter, chromium and cadmium. The effects of process factors (sediment weight ratio to phosphoric acid, temperature and time reaction) on the removal of these impurities were determined and correlated to the mechanism of their elimination. The results predicted using linear model show high values of regression coefficients (R2 sulfate = 0.97, R2 fluoride = 0.97, R2 organic matter = 0.95, R2 Cr = 0.96 and R2 Cd = 0.86) indicating good agreement with experimental data. Optimization was carried out by using desirability function by targeting the factors to desired levels for maximum removal of these impurities. The efficiencies of removal of sulfate, fluoride, organic matters, chromium and cadmium were 63%, 81%, 78%, 15% and 19% respectively, with a global desirability of 0.75.