The sorption of selenite from aqueous solutions by pyrite

Selenium (Se) is an essential trace nutrient for mammals; however, the range between deficit and toxic levels is narrow. In this study, the potential sorption of selenite onto pyrite particles from an aqueous solution was investigated. An intraparticle diffusion model was used to describe kinetic data of sorption, yielding diffusivity values of 5 × 10^?7 cm²/s. The Langmuir isotherm equation could be used to describe the experimental data. The fitting results indicated that b and {Se(IV)}_max have values of 0.37 L/mg and 3.49 mg/g, respectively. The sorption of selenite onto the surface of pyrite particles was dependent on a pH range of 2–12, and the quantity of sorption onto pyrite was negatively correlated with pH; that is, the amount of sorption onto pyrite increased with a decrease in pH. In addition, organic matter did not exert a significant effect on removal of selenite. With a reaction time greater than 1 week, sorption of selenite onto pyrite particles was found to partially reduce the amount of elemental Se.