Halide removal from aqueous solution by novel silver-polymeric materials

The objective of this study was to analyze the behavior of a new material, silver-doped polymeric cloth (Ag-cloth), in the removal of bromide and iodide from waters. Silver is immobilized on the cloth, guaranteeing selective adsorption of the halide ions as retained silver halides that therefore do not pass into the solution. Results indicate that Ag-0 reacts with H2O2 in the first phases of the process, yielding Ag+ and superoxide radical; however, as the process advances, this radical favors Ag+ reduction. Increases in the concentration of H2O2 augment the capacity of the Ag-cloth to remove halides from the medium up to a maximum concentration (55 PM), above which the removal capacity remains constant (Xm congruent to 13-1.8 mg halide/g Ag-cloth). Thus, when there is excess H2O2 in the medium, secondary competitive reactions that take place in the process guarantee a constant Ag+ concentration, which defines the maximum adsorption capacity of Ag-cloth, reducing, its ability to remove halides. Ag-cloth has a higher capacity to remove iodide than bromide, and the presence of organic matter or chloride reduces its capacity to remove iodide or bromide from water. The results obtained shown that the capacity of Ag with H2O2 significantly varies as a function of the medium pH from 1 mg Br-/g Ag-cloth at very low pH to 1.6 mg/g Ag-cloth at pH 9. (C) 2016 Elsevier B.V. All rights reserved.