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 reacts with HO 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 HO augment the capacity of the Ag-cloth to remove halides from the medium up to a maximum concentration (55μM), above which the removal capacity remains constant (Xm≅1.3-1.8mg halide/g Ag-cloth). Thus, when there is excess HO 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 HO significantly varies as a function of the medium pH from 1mg Br/g Ag-cloth at very low pH to 1.6mg/g Ag-cloth at pH9.