Efficient purification of Moroccan wet-process phosphoric acid via urea phosphate intermediate: High impurity removal with simultaneous urea nitrate production

Phosphoric acid (PA) is one of the most critical raw materials for global fertilizer production and chemical industries; however, untreated Moroccan phosphoric acid offers significant challenges due to impurities.This study presents a novel two-step purification method for untreated Moroccan PA by incorporating nitrogen fertilizers to produce a high-quality valorized product.The process involved the reaction between untreated Moroccan PA and urea to produce a crystalline urea phosphate (UP), followed by the treatment with concentrated nitric acid (NA) to generate urea nitrate (UN) and recover purified PA simultaneously.An extensive characterization analysis was performed using X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), inductively coupled plasma optical emission spectroscopy (ICP-OES), and scanning electron microscopy (SEM) coupled with energy dispersive X-ray spectroscopy (EDX), validating substantial P 2 O 5 recovery and reduction in metallic impurities.This purification methodology emphasizes an ecologically safe and sustainable process by minimizing waste and implementing safe production reagents.The analytical characterization demonstrated significant removal of contaminants and improved phosphoric acid quality as untreated PA (52.66 wt% P 2 O 5 ) was refined to purified PA (49.80 wt% P 2 O 5 ), highlighting the potential use of this purification method for industrial applications.ICP-OES analysis demonstrated high removal efficiencies for major metallic impurities -Al (99.05%),Fe (97.42%), and Mg (99.26%) -with a global P 2 O 5 recovery yield of 71.40% for purified PA, and total product (PA + UN) recovery reach 77.28%.UN by-products can be also efficiently utilized in agricultural applications as a potential nitrogen fertilizer.Furthermore, this process efficiently operates at 50 °C and consumes only 320 MJ per one ton of thermal energy, indicating an 87% reduction in comparison to conventional methods.This dual valorization approach perfectly aligns with the principles of green chemistry, contributing to the circular economy and presenting an environmentally sustainable alternative to conventional purification methods while offering industrial scalability and economic validity.