Ricou-Hoeffer P, Lecuyer I, Le Cloirec P
Ecole des Mines de Nantes, Département Systèmes Energétiques et Environnement, France.
Water Res. 2001 Mar;35(4):965-76. doi: 10.1016/s0043-1354(00)00341-9.
The objective of this study was to define operating conditions which would conciliate a high removal of the five metallic cations (Cu2+, Ni2+, Zn2+, Cd2+, Pb2+) and a low desorption of these metal ions from the contaminated sorbents. To achieve this goal the strategy relied on the use of experimental design methodology. The influence of four parameters (fly ash/lime mass ratio, type of fly ash/lime sorbent, solution temperature, and sorbent concentration) on the removal at pH = 5 and the stabilization of the five metallic ions was studied. In the first step, the influence of three parameters on the removal of Cu2+ ions was studied (R2 = fly ash/lime mass ratio, type of sorbent, temperature). It was found that the same set of parameter values would produce both the highest removal and the lowest desorption for this cation: R2 = 9 g g(-1), sorbent B (made by mixing fly ash and lime in water, then drying this paste at 105 degrees C for 24 h), temperature of suspension equal to 60 degrees C. The formation of calcium silicate hydrate (CSH), resulting from the pozzolanic activity of fly ash, is assumed to be partially responsible for these mechanisms. In the second step, simplex methodology and Doehlert matrix were used to find the conditions in a 2D space (sorbent concentration, temperature of solution) that would give the highest removal from a solution containing five metallic cations and the lowest desorption of these five cations adsorbed on the contaminated sorbents. Then, the system response that had to be optimized was the total metallic ions concentration (TMIC, mol L(-1)). A TMIC was measured both for adsorption and leaching experiments. These responses were modelized using a second-order polynomial and the surface responses were plotted for adsorption and desorption results. A difference was observed between operating conditions reaching the highest adsorption from those that gave the lowest desorption. However, an adsorbent concentration around 122 g L(-1) and a solution temperature of 66 degrees C would lead simultaneously to a high adsorption and a low desorption.
本研究的目的是确定操作条件，以实现对五种金属阳离子（Cu2+、Ni2+、Zn2+、Cd2+、Pb2+）的高去除率以及这些金属离子从受污染吸附剂上的低解吸率。为实现这一目标，该策略依赖于实验设计方法的应用。研究了四个参数（粉煤灰/石灰质量比、粉煤灰/石灰吸附剂类型、溶液温度和吸附剂浓度）对pH = 5时的去除率以及五种金属离子稳定性的影响。第一步，研究了三个参数对Cu2+离子去除率的影响（R2 = 粉煤灰/石灰质量比、吸附剂类型、温度）。结果发现，对于该阳离子，相同的一组参数值既能产生最高的去除率，又能产生最低的解吸率：R2 = 9 g g(-1)，吸附剂B（通过将粉煤灰和石灰在水中混合，然后在105℃下干燥该糊状物24小时制成），悬浮液温度等于60℃。粉煤灰的火山灰活性导致的硅酸钙水合物（CSH）的形成被认为部分负责这些机制。第二步，使用单纯形法和多勒特矩阵在二维空间（吸附剂浓度、溶液温度）中找到条件，以实现从含有五种金属阳离子的溶液中获得最高去除率以及使吸附在受污染吸附剂上的这五种阳离子的解吸率最低。然后，必须优化的系统响应是总金属离子浓度（TMIC，mol L(-1)）。在吸附和解吸实验中均测量了TMIC。使用二阶多项式对这些响应进行建模，并绘制吸附和解吸结果的表面响应图。观察到达到最高吸附的操作条件与产生最低解吸的操作条件之间存在差异。然而，吸附剂浓度约为122 g L(-1)且溶液温度为66℃会同时导致高吸附和低解吸。
