Electrodialysis of Phosphates in Industrial-Grade Phosphoric Acid

Table 3

Average composition of two industrial phosphoric acid samples.

Species	Concentration	Milliequivalents of solute per liter
P2O5	54% w/w	—
SO4^2−	13.4480 g/L	(−) 274.0
CaO	8.4116 g/L	(+) 299.9
SiO2	18.0240 g/L	(SiO4^4−) (−) 1199.9
Fe2O3	7.9843 g/L	(+) 149.9
Al2O3	8.1567 g/L	(+) 239.9
MgO	4.8364 g/L	(+) 239.9
Na2O	3.0989 g/L	(+) 99.9
K2O	3.7678 g/L	(+) 79.9
HF	3.4196 g/L	(−) 170.9
HCl	0.1773 g/L	(−) 93.7

The phosphoric acid concentration is typically expressed in terms of the P₂O₅ concentration. The conversion formula is as follows: [H₃PO₄] = [P₂O₅] × 196/142. Thus, 54% P₂O₅ concentration corresponds to an acid concentration of 74.5%.