Al Mardini Fadi, Legube Bernard
Université de Poitiers, CNRS, Laboratoire de Chimie et Microbiologie de l'Eau (UMR 6008), Ecole Supérieure d'Ingénieurs de Poitiers, 40 Avenue du Recteur Pineau, 86022 Poitiers Cedex, France.
J Hazard Mater. 2009 Oct 30;170(2-3):754-62. doi: 10.1016/j.jhazmat.2009.05.087. Epub 2009 May 22.
The application of several monosolute equilibrium models has previously shown that Bromacil adsorption on SA-UF (Norit) powdered activated carbon (PAC) is probably effective on two types of sites. High reactivity sites were found to be 10-20 less present in a carbon surface than lower reactivity sites, according to the q(m) values calculated by isotherm models. The aims of this work were trying, primarily, to identify the kinetic-determinant stage of the sorption of Bromacil at a wide range of initial pesticide concentrations (approximately 5 to approximately 500 microg L(-1) at pH 7.8), and secondly, to specify the rate constants and other useful design parameters for the application in water treatment. It was therefore not possible to specify a priori whether the diffusion or surface reaction is the key step. It shows that many of the tested models which describe the stage of distribution or the surface reaction are correctly applied. However, the diffusivity values (D and D(0)) were found to be constant only constants for some specific experimental concentrations. The HSDM model of surface diffusion in pores was also applied but the values of the diffusion coefficient of surface (D(s)) were widely scattered and reduce significantly with the initial concentration or the equilibrium concentration in Bromacil. The model of surface reaction of pseudo-second order fitted particularly well and led to constant values which are independent of the equilibrium concentration, except for the low concentrations where the constants become significantly more important. This last observation confirms perfectly the hypothesis based on two types of sites as concluded by the equilibrium data (part 1).
先前应用的几种单溶质平衡模型表明，溴莠定在SA-UF（Norit）粉末活性炭（PAC）上的吸附可能在两种类型的位点上有效。根据等温线模型计算的q(m)值，发现高反应性位点在碳表面的存在量比低反应性位点少10 - 20倍。这项工作的目的主要是确定在广泛的初始农药浓度范围（pH 7.8时约5至约500 μg L(-1)）下溴莠定吸附的动力学决定阶段，其次是确定速率常数和其他用于水处理应用的有用设计参数。因此，无法预先确定扩散还是表面反应是关键步骤。结果表明，许多描述分布阶段或表面反应的测试模型得到了正确应用。然而，扩散率值（D和D(0)）仅在某些特定实验浓度下为常数。还应用了孔隙中表面扩散的HSDM模型，但表面扩散系数（D(s)）的值广泛分散，并且随着溴莠定的初始浓度或平衡浓度而显著降低。伪二级表面反应模型拟合得特别好，除了在低浓度下常数变得明显更大外，得到的常数值与平衡浓度无关。最后这一观察结果完美地证实了基于平衡数据（第1部分）得出的关于两种类型位点的假设。
