Removal of iodide anions in water by silver nanoparticles supported on polystyrene anion exchanger
Jing-Fu Liu , Li Li , Su-Juan Yu , Rong-Gang Zheng , Peng Li , Qing-Cun Li
DOI:10.1016/j.jes.2022.08.012
Received May 19, 2022,Revised , Accepted August 06, 2022, Available online August 21, 2022
Volume 35,2023,Pages 45-54
The removal of iodide (I−) from source waters is an effective strategy to minimize the formation of iodinated disinfection by-products (DBPs), which are more toxic than their brominated and chlorinated analogues. In this work, a nanocomposite Ag-D201 was synthesized by multiple in situ reduction of Ag-complex in D201 polymer matrix, to achieve highly efficient removal of iodide from water. Scanning electron microscope /energy dispersive spectrometer characterization showed that uniform cubic silver nanoparticles (AgNPs) evenly dispersed in the D201 pores. The equilibrium isotherms data for iodide adsorption onto Ag-D201 was well fitted with Langmuir isotherm with the adsorption capacity of 533 mg/g at neutral pH. The adsorption capacity of Ag-D201 increased with the decrease of pH in acidic aqueous solution, and reached the maximum value of 802 mg/g at pH 2. This was attributed to the oxidization of I−, by dissolved oxygen under the catalysis of AgNPs, to I2 which was finally adsorbed as AgI3. However, the aqueous solutions at pH 7 – 11 could hardly affect the iodide adsorption. The adsorption of I− was barely affected by real water matrixes such as competitive anions (SO42−, NO3−, HCO3−, Cl−) and natural organic matter, of which interference of NOM was offset by the presence of Ca2+. The proposed synergistic mechanism for the excellent performance of iodide adsorption by the absorbent was ascribed to the Donnan membrane effect caused by the D201 resin, the chemisorption of I− by AgNPs, and the catalytic effect of AgNPs.
