Sperlich Alexander, Werner Arne, Genz Arne, Amy Gary, Worch Eckhard, Jekel Martin
Department of Water Quality Control, Technical University of Berlin, Sekr. KF 4, Strasse des 17. Juni 135, 10623 Berlin, Germany.
Water Res. 2005 Mar;39(6):1190-8. doi: 10.1016/j.watres.2004.12.032.
Breakthrough curves (BTC) for the adsorption of arsenate and salicylic acid onto granulated ferric hydroxide (GFH) in fixed-bed adsorbers were experimentally determined and modeled using the homogeneous surface diffusion model (HSDM). The input parameters for the HSDM, the Freundlich isotherm constants and mass transfer coefficients for film and surface diffusion, were experimentally determined. The BTC for salicylic acid revealed a shape typical for trace organic compound adsorption onto activated carbon, and model results agreed well with the experimental curves. Unlike salicylic acid, arsenate BTCs showed a non-ideal shape with a leveling off at c/c0 approximately 0.6. Model results based on the experimentally derived parameters over-predicted the point of arsenic breakthrough for all simulated curves, lab-scale or full-scale, and were unable to catch the shape of the curve. The use of a much lower surface diffusion coefficient D(S) for modeling led to an improved fit of the later stages of the BTC shape, pointing on a time-dependent D(S). The mechanism for this time dependence is still unknown. Surface precipitation was discussed as one possible removal mechanism for arsenate besides pure adsorption interfering the determination of Freundlich constants and D(S). Rapid small-scale column tests (RSSCT) proved to be a powerful experimental alternative to the modeling procedure for arsenic.
通过实验测定了固定床吸附器中颗粒氢氧化铁（GFH）对砷酸盐和水杨酸的吸附突破曲线（BTC），并使用均相表面扩散模型（HSDM）进行了模拟。通过实验确定了HSDM的输入参数，即Freundlich等温线常数以及膜扩散和表面扩散的传质系数。水杨酸的BTC呈现出痕量有机化合物在活性炭上吸附的典型形状，模型结果与实验曲线吻合良好。与水杨酸不同，砷酸盐的BTC呈现出非理想形状，在c/c0约为0.6时趋于平稳。基于实验得出的参数的模型结果对所有模拟曲线（实验室规模或全尺寸）的砷突破点预测过高，并且无法捕捉曲线形状。使用低得多的表面扩散系数D(S)进行建模可改善BTC形状后期的拟合，表明D(S)与时间有关。这种时间依赖性的机制仍然未知。除了纯吸附干扰Freundlich常数和D(S)的测定外，还讨论了表面沉淀作为砷酸盐的一种可能去除机制。快速小规模柱试验（RSSCT）被证明是砷建模过程的一种强大实验替代方法。
