Sequential Steps for Purifying Wet Processed Phosphoric Acid for Producing a High-Tech Grade and Barium or Ammonium Phosphate Salts

Abstract

Batch experiments were used in this study to investigate the cleaning of phosphoric acid solution from cationic impurities. A set of steps was used to clean up wet-processed phosphoric acid to technical grade phosphoric acid, which included solvent extraction, scrubbing, stripping, evaporation, contacting the produced phosphoric acid with two types of carbon (activated carbon as received and oxidized activated carbon) for 1 h, filtration, neutralizing the acid with ammonia solution to pH 7 to produce soluble salt of ammonium phosphate, filtration, again contacting the phosphate salt solution with the two types of carbon for 1 h. Finally, contacting it with resin Amberlite IR 120-H- form or adding sulfuric acid to obtain purified technical grade phosphoric acid or producing barium or ammonium phosphate salts. Different variables that influence the adsorption process were examined, including medium acidity, shaking time, adsorbent-to-volume ratio, temperature, and phosphoric acid initial concentrations. The adsorption isotherms, the Langmuir isotherm model (R² = 0.99), and the Freundlich model (R² = 0.76) were studied to assess the maximal removal efficacy of adsorbents; it was found that the experimental results agreed with the Langmuir isotherm.