Silver ions immobilized on thiourea/formaldehyde resin for solid phase extraction of iodide ions from aqueous solution

Abstract

Iodine has been found to have considerable effects on tropospheric photochemistry, which in turn affects climate by lowering ozone's radiative forcing and air quality by lowering extreme O3 concentrations in polluted areas. The majority of the iodine that naturally occurs in the water is in the form of aqueous iodide and iodate. To extract iodide from the aqueous solution, thiourea-formaldehyde resin (TF) was prepared by condensation polymerization and then loaded with Ag(I) ions (Ag-TF). TF resin was characterized by a specific surface area close to 111.3 m2 g−1, and nitrogen and sulphur content of 20.57 and 10.01 mmol g−1, respectively. After calculation of the adsorbed amount of Ag(I) ions, the prepared Ag-TF adsorbent was introduced for the solid phase extraction of iodide anions under various operational parameters of pH (e.g., 1.6 – 10.7), adsorbent dose (e.g., 0.5 – 5.0 g L−1), primary iodide concentrations (e.g., 0.075 – 3.96 mmol L−1), and residence time (e.g., 5 – 400 min), and sonication time (e.g., 5–45 min). The findings revealed that the adsorption of iodide onto as-produced TF adsorbent was matched with the Langmuir model with a prominent loading capacity of 1.26 mmol g−1, under an optimized pH value of 2.7. The study of uptake kinetics investigates the influence of the mode of agitation; comparing more specifically the performance of mechanical agitation with those obtained with ultrasonication (at frequencies of 37 and 80 kHz). The ultra-sonication treatment decreased interestingly the adsorption equilibrium time from 400 min to only 45 min. Overall, the present study illustrates the susceptibility of Ag-TF adsorbent as a promising material for the efficient elimination of I− anions from an aqueous medium.