Studies on the Development of Iodine Recovery Process with High Yield and Purity from NH 4 I Solution

In this paper, we have investigated the optimization of I2 recovery process from NH4I solution, which is generated as by-prod- uct during the amination reaction of p-diiodobenzene (PDIB) for p-phenylenediamine (PPD) synthesis. The recovered I2 is then recycled as a raw material for PDIB synthesis. We have employed a cation exchange resin to recover I2 from NH4I sample solution, and determined the breakthrough point and exchange capacity from the breakthrough curve. Furthermore, we have suggested optimum conditions of our I2 recovery process by measuring the purity and yield of recovered I2 with respect to the concentrations of NH4I and oxidant (H2O2) solutions, the oxidation time, and the temperature of drying process. Finally, the yield and purity as high as 94.96% and 96.65%, respectively were obtained by reusing the residual solution still containing unrecovered iodide ions.