Laboratoire de Chimie Moléculaire et Environnement, Polytech Savoie, 73376 Le Bourget du Lac Cedex, France.
J Colloid Interface Sci. 2009 Nov 15;339(2):275-84. doi: 10.1016/j.jcis.2009.07.057. Epub 2009 Jul 28.
The adsorption of two anionic dyes, Remazol Black B (RB5) and Acidol Red 2BE-NW (AR42), onto a microporous activated carbon felt was investigated. The characterization of carbon surface chemistry by X-ray microanalysis, Boehm titrations, and pH-PZC measurements indicates that the surface oxygenated groups are mainly acidic. The rate of adsorption depends on the pH and the experimental data fit the intraparticle diffusion model. The pore size distribution obtained by DFT analysis shows that the mean pore size is close to 1nm, which indicates that a slow intraparticle diffusion process control the adsorption. The adsorption isotherms were measured for different pH values. The Khan and the Langmuir-Freundlich models lead to the best agreement with experimental data for RB5 and AR42, respectively. These isotherm simulations and the pH dependence of adsorption show that the adsorption capacity is mainly controlled by nondispersive electrostatic interactions for pH values below 4. The adsorption kinetics, the irreversibility of the process, and the influence of the pH indicate that the rate of adsorption in this microporous felt proceeds through two steps. The first one is fast and results from direct interaction of dye molecules with the external surface of the carbon material (which account for 10% of the whole surface area); in the second, slow step, the adsorption rate is controlled by the slow diffusion of dye molecules into the narrow micropores. The influence of temperature on the adsorption isotherms was studied and the thermodynamic parameters were obtained. They show that the process is spontaneous and exothermic.
研究了两种阴离子染料，Remazol Black B（RB5）和 Acidol Red 2BE-NW（AR42）在微孔活性炭毡上的吸附。X 射线微分析、Boehm 滴定和 pH-PZC 测量表明，表面含氧基团主要为酸性，对碳表面化学性质进行了表征。吸附速率取决于 pH 值，实验数据符合内扩散模型。通过 DFT 分析得到的孔径分布表明，平均孔径接近 1nm，表明吸附过程受到缓慢的内扩散控制。在不同 pH 值下测量了吸附等温线。对于 RB5 和 AR42，Khan 和 Langmuir-Freundlich 模型分别与实验数据拟合得最好。这些等温线模拟和吸附的 pH 依赖性表明，在 pH 值低于 4 时，吸附容量主要受非分散静电相互作用控制。吸附动力学、过程的不可逆性以及 pH 值的影响表明，在这种微孔毡中，吸附速率通过两个步骤进行。第一步很快，是由于染料分子与碳材料的外表面直接相互作用（占整个表面积的 10%）；在第二步，缓慢的步骤中，吸附速率受染料分子缓慢扩散到狭窄微孔中的控制。研究了温度对吸附等温线的影响，并得到了热力学参数。它们表明该过程是自发的和放热的。
