Iodide ion trapping polypyrrole film: selective capture of iodide ions by electrochemically switched ion extraction (ESIE) process

Abstract Effective extraction of iodide ions (I−) from low-concentration brine or radioactive wastewater remains a great challenge. In this study, an electroactive I− trapping polypyrrole film (PPy/I− film) was fabricated via a facile one-step electrodeposition method and used in a novel and effective electrochemically switched ion extraction (ESIE) system for capture of I− from dilute aqueous solutions. Herein, the PPy/I− film displayed superior performance owing to the special I− trapping efficiency. The extraction capacity as high as 287 mg/g was achieved in 5 ppm KI solution, and the separation factors for I−/Cl−, I−/Br−, I−/SO42−, I−/PO43− were 6.93, 22.16, 15.92, 7.92, respectively. Moreover, the desorption efficiency of I− from the PPy/I− film extracted with I− was approximately 100% even after several repeated cycles. It manifested that the present ESIE system with the PPy/I− film had efficient extraction capacity, remarkable selectivity and excellent recyclability, which could be applied in the extraction of I− from the dilute industrial solutions.