The influence of different operational variables on the production of crystalline monopotassium phosphate

Monopotassium phosphate stands out as a valuable fertilizer due to its abundance of potassium and phosphate in a form that plants can easily utilize. Boasting an impressive total plant food content of almost 87%, it outshines numerous other fertilizers in terms of nutrient concentration. Moreover, its low salt index and high water solubility make it an indispensable resource for promoting robust root development in plants. The production of monopotassium phosphate (MKP) is highly important to various industries due to its wide range of applications, particularly in agriculture, fertilizer manufacturing, and other sectors. Experimental investigations were carried out in this research to identify the most feasible operating conditions for synthesizing pure and clear crystalline monopotassium phosphate by reacting commercial potassium hydroxide with commercial furnace-grade phosphoric acid. The study focused on analyzing five operating variables, which comprised reaction temperature and time, crystallization temperature and time, and the molar ratio of H₃PO₄ to KOH. The primary factors considered in determining the best operating conditions were the size of the crystals obtained and the yield. The most feasible operating conditions were found to be a reaction temperature of 50°C, a reaction time of 60 minutes, a crystallization temperature of 10°C, a crystallization time of 60 minutes, and a molar ratio of 1 H₃PO₄ to 1 KOH, which resulted in a reasonable yield (73 wt%) and a satisfactory monopotassium phosphate crystal size.