ADSORPTION OF SELENITE TO GOETHITE IN A FLOW-THROUGH REACTION CHAMBER

Adsorption of selenite on goethites in NaCl and Na2SO4 solutions was p erformed in a newly designed flow-through reaction chamber as well as in a traditional batch system. Six goethites with different morphologi es were used as adsorbents. For the experiments the goethite was place d in the chamber prior to flushing with the salts. Introduction of the NaCl and Na2SO4 solutions only, and in combination with selenite, res ulted in different responses with respect to the pH. The pH changes we re explained by means of anion-binding energies, with Cl- <SO42- <SeO3 2-. Neither the morphological characteristics of the adsorbents nor th e electrolyte anion influenced the amount and the rate of selenite ads orption. The mixing mode in the reactor chamber affected the selenite adsorption density, as indicated by higher densities in the batch expe riments.