Dragan Ecaterina Stela, Humelnicu Doina, Dinu Maria Valentina
Department of Functional Polymers, "Petru Poni" Institute of Macromolecular Chemistry, Grigore Ghica Voda Alley 41 A, 700487 Iasi, Romania.
Faculty of Chemistry, Alexandru Ioan Cuza University of Iasi, Carol I Bd. 11, 700506 Iasi, Romania.
Polymers (Basel). 2023 Feb 10;15(4):885. doi: 10.3390/polym15040885.
It is still a challenge to develop advanced materials able to simultaneously remove more than one pollutant. Exclusive cationic composite double- and triple-network cryogels, with adequate sustainability in the removal of CrO and HPO oxyanions, were developed in this work starting from single-network (SN) sponges. Chitosan (CS), as the only polycation originating from renewable resources, and poly(N,N-dimethylaminoethylmethacrylate) (PDMAEMA) and polyethyleneimine (PEI), as synthetic polycations, were employed to construct multi-network cationic composite cryogels. The properties of the composites were tailored by the cross-linking degree of the first network (SN5 and SN20, which means CS with 5 or 20 mole % of glutaraldehyde, respectively) and by the order of the successive networks. FTIR, SEM-EDX, equilibrium water content and compressive tests were used in the exhaustive characterization of these polymeric composites. The sorption performances towards CrO and HPO anions were evaluated in batch mode. The pseudo-first-order, pseudo-second-order (PSO) and Elovich kinetics models, and the Langmuir, Freundlich and Sips isotherm models were used to interpret the experimental results. The adsorption data were the best fitted by the PSO kinetic model and by the Sips isotherm model, indicating that the sorption mechanism was mainly controlled by chemisorption, irrespective of the structure and number of networks. The maximum sorption capacity for both oxyanions increased with the increase in the number of networks, the highest values being found for the multi-network sponges having SN5 cryogel as the first network. In binary systems, all sorbents preferred CrO ions, the selectivity coefficient being the highest for TN sponges. The high sorption capacity and remarkable reusability, with only a 4-6% drop in the sorption capacity after five sorption-desorption cycles, recommend these composite cryogels in the removal of two of the most dangerous pollutants represented by CrO and HPO.
开发能够同时去除多种污染物的先进材料仍然是一项挑战。在这项工作中，从单网络（SN）海绵出发，制备了具有足够可持续性以去除CrO和HPO含氧阴离子的独家阳离子复合双网络和三网络冷冻凝胶。壳聚糖（CS）作为唯一源自可再生资源的聚阳离子，以及聚（N，N-二甲基氨基乙基甲基丙烯酸酯）（PDMAEMA）和聚乙烯亚胺（PEI）作为合成聚阳离子，被用于构建多网络阳离子复合冷冻凝胶。通过第一个网络的交联度（SN5和SN20，分别表示含有5或20摩尔%戊二醛的CS）和连续网络的顺序来调整复合材料的性能。FTIR、SEM-EDX、平衡含水量和压缩试验用于对这些聚合物复合材料进行详尽表征。以分批模式评估对CrO和HPO阴离子的吸附性能。使用伪一级、伪二级（PSO）和Elovich动力学模型以及Langmuir、Freundlich和Sips等温线模型来解释实验结果。吸附数据与PSO动力学模型和Sips等温线模型拟合得最好，表明吸附机制主要受化学吸附控制，而与网络的结构和数量无关。两种含氧阴离子的最大吸附容量随着网络数量的增加而增加，以SN5冷冻凝胶作为第一个网络的多网络海绵的吸附容量最高。在二元体系中，所有吸附剂都优先吸附CrO离子，TN海绵的选择性系数最高。这些复合冷冻凝胶具有高吸附容量和显著的可重复使用性，在五个吸附-解吸循环后吸附容量仅下降4-6%，推荐用于去除由CrO和HPO代表的两种最危险的污染物。
