Halide removal from water using silver doped magnetic-microparticles

This study proposes the use of new materials based on core-shell structure magnetic microparticles with Ag0 (Ag(0)-MPs) on their surface to remove bromides and chlorides from waters intended for human consumption. Hydrogen peroxide was used as oxidizing agent, Ag(0)-MPs is thereby oxidized to Ag (I)-MPs, which, when in contact with Cl− and Br− ions, form the corresponding silver halide (AgCl and AgBr) on the surface of Ag-MPs. The concentration of Cl− and Br− ions was followed by using ion selective electrodes (ISEs). Silver microparticles were characterized by high-resolution scanning electron microscopy and X-ray photoelectron spectroscopy, while the presence of AgCl and AgBr on Ag-MPs was determined by microanalysis. We analyzed the influence of operational variables, including: hydrogen peroxide concentration in Ag-MP system, medium pH, influence of Cl− ions on Br− ion removal, and influence of tannic acid as surrogate of organic matter in the medium. Regarding the influence of pH, Br−and Cl− removal was constant within the pH range studied (3.5–7), being more effective for Br− than for Cl− ions. Accordingly, this research states that the system Ag-MPs/H2O2 can remove up to 67.01% of Br− ions and 56.92% of Cl− ions from water (pH = 7, [Ag-MPs]0 = 100 mg L−1, [H2O2]0 = 0.2 mM); it is reusable, regenerated by radiation and can be easily removed by applying a magnetically assisted chemical separation process. [Display omitted] •Halide ion removal from the medium can be achieved by using Ag-MPs/H2O2 process.•The effectiveness of the Ag-MPs/H2O2 system depends on the medium pH, and on the presence of dissolved organic matter.•Ag-MPs can be regenerated with UV or solar radiation.•The cytotoxicity study indicates that Ag-MPs are not toxic at the concentrations studied.