Mass transfer process study of Fe(III) extraction from ammonium dihydrogen phosphate solution

The crystallization of ammonium dihydrogen phosphate (MAP) is largely affected by certain metal ions such as Fe (III), and the influence seems to be pointed at both ends. Therefore, the industrial-grade MAP products can only be obtained by purifying the neutralized MAP solution from wet-process phosphoric acid (WPA). The extraction kinetics of Fe (III) from MAP solution using di-2-ethylhexyl phosphoric acid (D2EHPA) in sulfonated kerosene mea­sured by the Lewis cell. The extraction mechanism is discussed and confirmed on the basis of the dimeric model of D2EHPA in non-polar solution. From the temperature dependence of reaction rate, the value of E a and K f are cal­culated and the extraction regimes are deduced to be mixed controlled with dif­fusion and chemical reaction for Fe (III). Ultimately, the rate equation for the ext­ract­ion reaction of Fe (III) with D2EHPA is obtained as follows: R f = 0.028 c Fe 3+ 1.2 c H 2 A 2 0.81 c H + -0.85.