Abstract

Polymers of Intrinsic Microporosity (PIMs) are recognized as promising polymers for active separation of organic pollutants. These highly porous and solution-processable polymers could be tailored to remove specific targets from an aqueous system. In this study, PIM-1 powder was modified to amidoxime PIM-1 powder and adsorption of charged dyes which are Methylene Blue (MB, cationic) and Methyl Orange (MO, anionic) from an aqueous system was explored to evaluate the influence of contact time, initial concentration, solution pH and temperature on the removal of dyes. The adsorption reached the equilibrium within three hours in a batch adsorption process for both dyes. Experimental adsorption capacity (q_{e, exp}) of Amidoxime PIM-1 was found as 79.8 mg g⁻¹ and 69.8 mg g⁻¹ for MO and MB, respectively at pH 6 and 298 K. The Amidoxime PIM-1 was also able to remove a mixture of anionic and cationic dyes simultaneously from aqueous system. The removal ability is dependent on the solution pH and the selectivity can be tuned by shifting solution pH such as at low pH (pH 3) anionic dye adsorption is more favourable, while at high pH (pH 10) cationic dye adsorption is preferable. Equilibrium data acquired from batch adsorption experiments have been examined by four two-parameter (Langmuir, Freundlich, Temkin and Dubinin–Radushkevich), four three-parameter (Redlich–Peterson, Sips, Khan and Liu) isotherm models, and by kinetic models such as the pseudo-first-order, the pseudo-second-order, Elovich equation and intraparticle diffusion using non-linear regression technique. Combination of several errors analysis techniques was applied to find the best fitting isotherm and kinetic models. Liu isotherm was the best to define the experimental data and the maximum adsorption capacities (q_m) were calculated as 86.7 mg g⁻¹ and 81.3 mg g⁻¹ for MO and MB, respectively at pH 6 and 298 K. Adsorption data have the best consistency with the pseudo-second-order kinetic model. Furthermore, thermodynamic parameters were determined and the experiments suggested that the adsorption of MB and MO onto Amidoxime PIM-1 is a physical, spontaneous and exothermic.

Graphic Abstract

摘要

本征微孔聚合物（PIM）被认为是用于有机污染物主动分离的有前途的聚合物。这些高度多孔和可溶液加工的聚合物可以定制以从水性体系中除去特定的目标。在这项研究中，将PIM-1粉末改性为a肟PIM-1粉末，并探索了水性体系对亚甲基蓝（MB，阳离子）和甲基橙（MO，阴离子）的带电染料的吸附，以评估接触的影响时间，初始浓度，溶液的pH值和温度对去除染料的影响。在两种染料的分批吸附过程中，吸附在三个小时内达到平衡。发现mid胺肟PIM-1的实验吸附容量（q _e，exp）为79.8 mg g ^-1和69.8 mg g^-1分别在pH为6和298 K的条件下测定MO和MB。A胺肟PIM-1还能够同时从水性体系中除去阴离子和阳离子染料的混合物。去除能力取决于溶液的pH，并且可以通过改变溶液的pH来调节选择性，例如在低pH（pH 3）下，阴离子染料吸附是更有利的，而在高pH（pH 10）下，阳离子染料的吸附是优选的。通过四个二参数（Langmuir，Freundlich，Temkin和Dubinin-Radushkevich），四个三参数（Redlich-Peterson，Sips，Khan和Liu）等温线模型以及动力学模型，对间歇吸附实验获得的平衡数据进行了检验。作为伪一阶，伪二阶，Elovich方程和使用非线性回归技术的粒子内扩散。应用了几种误差分析技术的组合，以找到最佳拟合等温线和动力学模型。Liu等温线是定义实验数据和最大吸附容量的最佳方法（在pH为6和298 K时，MO和MB的q _m）计算值分别为86.7 mg g ^-1和81.3 mg g ^-1。吸附数据与拟二级动力学模型具有最佳一致性。此外，确定了热力学参数并且实验表明MB和MO在A胺肟PIM-1上的吸附是物理的，自发的并且是放热的。

图形摘要