The effect of pH on chlorite dissolution rates at 25°C

摘要: The Swedish nuclear industry is planing to dispose spent fuel encapsulated in copper canisters granitic bedrock at a depth of approx. 500 m. reducing capacity the geo-sphere important for canister corrosion and radionuclide migration. main inorganic reduc-tants are Fe(II)-containing minerals: biotite bedrock, pyrite chlorite fracture filling minerals as well buffer backfill. As consequence, dissolution an parameter when considering available groundwaters around repository. weathering rates sample from Taberg central Sweden has been studied 0.01 M NaCl media (25±1)°C pH region 2–12. was characterized before after grinding sieving, found have relatively low Fe-content, with formula (Mg 9.44 Fe II 0.72 Al 1.68 )(Si 6.47 1.4 III 0.13 )O 20 (OH) 16 . Kinetic experiments were performed using thin-film continuous flow-through technique flow 5 mL/h or 2.7 mL/h. This prevents precipitation secondary phases such iron(III) hydroxides. Solution samples taken reaction time 0–30 days. contents released Al, Fe, Mg Si analyzed Inductively Coupled Plasma emission spectroscopy (ICP-AES) then normalized Brunauer-Emmet-Teller (BET) surface area flow-rate order obtain dissolution. rate pH-dependent, minimum observed neutral region. (based on data) decreased 7×10 -11 mol/(m 2 s) pH=2 4×10 -13 pH≈7 in-creased 3×10 -12 mol(m pH=12.