Hydroxyl release of red soil and latosol surfaces was quantitatively measuredusing a self-made constant pH automated titration instrument, to study the changes of hydroxylrelease with different added selenite amounts ...Hydroxyl release of red soil and latosol surfaces was quantitatively measuredusing a self-made constant pH automated titration instrument, to study the changes of hydroxylrelease with different added selenite amounts and pH levels, and to study the effects ofelectrolytes on hydroxyl release. Hydroxyl release increased with the selenite concentration, with arapid increase at a low selenite concentration while slowing down at a high concentration. The pHwhere maximum of hydroxyl release appeared was not constant, shifting to a lower valus withincreasing selenite concentration. Hydroxyl release decreased with increasing electrolyteconcentration, and the decrease was very rapid at a low electrolyte concentration but slow at a highelectrolyte concentration. For NaClO_4, NaCl and Na_2SO_4, hydroxyl release was in the order ofNaClO_4 > NaCl >> Na_2SO_4, and the difference was very significant. But for NaCl, KCl and CaCl_2,the order of hydroxyl release was NaCl > KCl > CaCl_2, and the difference was smaller. The amount ofhydroxyl release from Xuwen latosol was greater than that from Jinxian red soil. Hydroxyl releaseexisted in a wider range of pH with Xuwen latosol than with Jinxian red soil, due to theirdifference in soil properties. However, both soils had similar curves of hydroxyl release,indicating the common characteristics of variable charge soils.展开更多
A self-made constant pH automated titration instrument was used to study thekinetics of hydroxyl release during selenite reacting with variable charge soils. The rate ofhydroxyl release was very rapid at the first sev...A self-made constant pH automated titration instrument was used to study thekinetics of hydroxyl release during selenite reacting with variable charge soils. The rate ofhydroxyl release was very rapid at the first several minutes, then gradually slowed down, and atlast did not change any more. The experimental data was well fitted by the Langmuir kineticequation, arid with increasing selenite concentration or decreasing solution pH, the reaction lastedlonger, the maximum of hydroxyl release (x_m) increased, and the binding constant (k) decreased.The time of hydroxyl release with Xuwen latosol was much longer than that with Jinxian red soil.展开更多
基金Project supported by the National Natural Science Foundation of China(Nos.49971046 and 49831005).
文摘Hydroxyl release of red soil and latosol surfaces was quantitatively measuredusing a self-made constant pH automated titration instrument, to study the changes of hydroxylrelease with different added selenite amounts and pH levels, and to study the effects ofelectrolytes on hydroxyl release. Hydroxyl release increased with the selenite concentration, with arapid increase at a low selenite concentration while slowing down at a high concentration. The pHwhere maximum of hydroxyl release appeared was not constant, shifting to a lower valus withincreasing selenite concentration. Hydroxyl release decreased with increasing electrolyteconcentration, and the decrease was very rapid at a low electrolyte concentration but slow at a highelectrolyte concentration. For NaClO_4, NaCl and Na_2SO_4, hydroxyl release was in the order ofNaClO_4 > NaCl >> Na_2SO_4, and the difference was very significant. But for NaCl, KCl and CaCl_2,the order of hydroxyl release was NaCl > KCl > CaCl_2, and the difference was smaller. The amount ofhydroxyl release from Xuwen latosol was greater than that from Jinxian red soil. Hydroxyl releaseexisted in a wider range of pH with Xuwen latosol than with Jinxian red soil, due to theirdifference in soil properties. However, both soils had similar curves of hydroxyl release,indicating the common characteristics of variable charge soils.
基金Project supported by the National Natural Science Foundation of China (Nos. 49971046 and 49831005).
文摘A self-made constant pH automated titration instrument was used to study thekinetics of hydroxyl release during selenite reacting with variable charge soils. The rate ofhydroxyl release was very rapid at the first several minutes, then gradually slowed down, and atlast did not change any more. The experimental data was well fitted by the Langmuir kineticequation, arid with increasing selenite concentration or decreasing solution pH, the reaction lastedlonger, the maximum of hydroxyl release (x_m) increased, and the binding constant (k) decreased.The time of hydroxyl release with Xuwen latosol was much longer than that with Jinxian red soil.
