Dynamic adsorption and elution processes were carried out in a glass column (internal diameter: 2 cm, length: 25 cm). The flow rate was controlled at 1 mL min−1 using a peristaltic pump (SHENCHEN, Lab 2015). The operations were performed as follows:
(a) Synthetic resin (001 × 7 or S957) was firstly loaded into the column, then the deionized water was fed from the top of the column to rinse the resin. The resin in the column was collected as the sample of the resin before the adsorption of metal ions.
(b) Phosphoric acid–nitric acid solutions (4.4 mol L−1 phosphoric acid and 1.1 mol L−1 nitric acid) containing 0.25 mol L−1 Ca2+ and Mg2+ ions, or 0.15 mol L−1 Fe3+ and Al3+ ions were prepared according to the typical compositions of the neutralization mother liquor obtained from the Chemical Group Co. Ltd of China.10 The prepared solution passed through the column in the upflow mode. After the end of the adsorption process, the deionized water was fed from the top of the column to rinse the phosphoric acid–nitric acid solution retained. The resin in the column was collected as the sample of the resin after the adsorption of metal ions.
(c) The regeneration solution (7 mol L−1 nitric acid solution or 8 mol L−1 hydrochloric acid solution) was flown through the column upward. After the end of the elution process, the deionized water was fed from the top of the column to rinse the regeneration solution retained. Resin in the column was collected as the sample of the resin after the elution of metal ions.
(a) Synthetic resin (001 × 7 or S957) was firstly loaded into the column, then the deionized water was fed from the top of the column to rinse the resin. The resin in the column was collected as the sample of the resin before the adsorption of metal ions.
(b) Phosphoric acid–nitric acid solutions (4.4 mol L−1 phosphoric acid and 1.1 mol L−1 nitric acid) containing 0.25 mol L−1 Ca2+ and Mg2+ ions, or 0.15 mol L−1 Fe3+ and Al3+ ions were prepared according to the typical compositions of the neutralization mother liquor obtained from the Chemical Group Co. Ltd of China.10 The prepared solution passed through the column in the upflow mode. After the end of the adsorption process, the deionized water was fed from the top of the column to rinse the phosphoric acid–nitric acid solution retained. The resin in the column was collected as the sample of the resin after the adsorption of metal ions.
(c) The regeneration solution (7 mol L−1 nitric acid solution or 8 mol L−1 hydrochloric acid solution) was flown through the column upward. After the end of the elution process, the deionized water was fed from the top of the column to rinse the regeneration solution retained. Resin in the column was collected as the sample of the resin after the elution of metal ions.
