Removal of iodides and bromides at parts per million concentrations using a novel bismuth composite material

Figure showing a schematic of experiment procedures for synthesis of bismuth composites. DI water, deionized water.
Elsevier, Materials Today Sustainability, Volume 10, December 2020
Nariyan E., Aravindakshan N., Yu Q.J., Li Q.

Iodide and bromide ions in surface and ground waters (typically less than 0.05 mg/L for iodide and 0.5 mg/L for bromide) could react with natural organic matters under oxidative disinfection process and produce toxic disinfectant by-products. Therefore, removal of iodides and bromides in water treatment is desirable for improving drinking water quality. We have synthesized a micro-nano Bi2O3-Bi2S3 composite via a carbogenic sphere-supported synthesis strategy. A hydrothermal processing of sucrose resulted in uniform spherical carbogenic microspheres, which served as an excellent substrate for reaction between Bi(NO3)3 and Na2SO4 in emulsion, forming Bi2O3-Bi2(SO4)3 composites, which was then converted into Bi2O3-Bi2S3 after calcination. Using 8 g/L of this material Bi2O3-Bi2S3, 87.69% of iodide at an initial concentration of 0.05 mg/L was removed after 3 h of contact, and 86.38% of bromide at an initial concentration of 0.5 mg/L was removed after 14 h. Such effective removal efficiency was retained when used in artificial groundwater treatment. Overall, this study developed a new method to produce the Bi2O3-Bi2S3 composite in high yield, and the as-synthesized Bi2O3-Bi2S3 composites exhibited high removal efficiencies toward I− and Br− through adsorption mechanism.