Wujcicki Łukasz, Mańdok Tomasz, Budzińska-Lipka Wiktoria, Pawlusińska Karolina, Szozda Natalia, Dudek Gabriela, Piotrowski Krzysztof, Turczyn Roman, Krzywiecki Maciej, Kazek-Kęsik Alicja, Kluczka Joanna
Faculty of Chemistry, Silesian University of Technology, Ks. M. Strzody 9, 44-100, Gliwice, Poland.
Department of Physical Chemistry and Technology of Polymers, Faculty of Chemistry, Silesian University of Technology, Ks. M. Strzody 9, 44-100, Gliwice, Poland.
Sci Rep. 2023 Aug 11;13(1):13049. doi: 10.1038/s41598-023-40064-1.
The excess presence of phosphate(V) ions in the biosphere is one of the most serious problems that negatively affect aqueous biocenosis. Thus, phosphates(V) separation is considered to be important for sustainable development. In the presented study, an original cerium(IV)-modified chitosan-based hydrogel (Ce-CTS) was developed using the chemical co-precipitation method and then used as an adsorbent for efficient removal of phosphate(V) ions from their aqueous solutions. From the scientific point of view, it represents a completely new physicochemical system. It was found that the adsorptive removal of phosphate(V) anions by the Ce-CTS adsorbent exceeded 98% efficiency which is ca. 4-times higher compared with the chitosan-based hydrogel without any modification (non-cross-linked CTS). The best result of the adsorption capacity of phosphates(V) on the Ce-CTS adsorbent, equal to 71.6 mg/g, was a result of adsorption from a solution with an initial phosphate(V) concentration 9.76 mg/dm and pH 7, an adsorbent dose of 1 g/dm, temperature 20 °C. The equilibrium interphase distribution data for the Ce-CTS adsorbent and aqueous solution of phosphates(V) agreed with the theoretical Redlich-Peterson and Hill adsorption isotherm models. From the kinetic point of view, the pseudo-second-order model explained the phosphates(V) adsorption rate for Ce-CTS adsorbent the best. The specific effect of porous structure of adsorbent influencing the diffusional mass transfer resistances was identified using Weber-Morris kinetic model. The thermodynamic study showed that the process was exothermic and the adsorption ran spontaneously. Modification of CTS with cerium(IV) resulted in the significant enhancement of the chitosan properties towards both physical adsorption (an increase of the point of zero charge of adsorbent), and chemical adsorption (through the presence of Ce(IV) that demonstrates a chemical affinity for phosphate(V) anions). The elaborated and experimentally verified highly effective adsorbent can be successfully applied to uptake phosphates(V) from aqueous systems. The Ce-CTS adsorbent is stable in the conditions of the adsorption process, no changes in the adsorbent structure or leaching of the inorganic filling were observed.
生物圈中磷酸根（V）离子的过量存在是对水生生物群落产生负面影响的最严重问题之一。因此，磷酸根（V）的分离被认为对可持续发展很重要。在本研究中，采用化学共沉淀法制备了一种新型铈（IV）改性壳聚糖基水凝胶（Ce-CTS），并将其用作吸附剂，以有效去除水溶液中的磷酸根（V）离子。从科学角度来看，它代表了一个全新的物理化学体系。研究发现，Ce-CTS吸附剂对磷酸根（V）阴离子的吸附去除效率超过98%，约为未改性的壳聚糖基水凝胶（非交联CTS）的4倍。Ce-CTS吸附剂对磷酸根（V）的最佳吸附容量为71.6 mg/g，这是在初始磷酸根（V）浓度为9.76 mg/dm³、pH值为7、吸附剂剂量为1 g/dm³、温度为20°C的溶液中吸附的结果。Ce-CTS吸附剂与磷酸根（V）水溶液的平衡相间分布数据符合理论Redlich-Peterson和Hill吸附等温线模型。从动力学角度来看，准二级模型对Ce-CTS吸附剂吸附磷酸根（V）的速率解释得最好。使用Weber-Morris动力学模型确定了吸附剂多孔结构对扩散传质阻力的具体影响。热力学研究表明，该过程是放热的，吸附是自发进行的。用铈（IV）对CTS进行改性，显著增强了壳聚糖在物理吸附（吸附剂零电荷点增加）和化学吸附（通过存在对磷酸根（V）阴离子具有化学亲和力的Ce（IV））方面的性能。精心制备并经实验验证的高效吸附剂可成功应用于从水体系中摄取磷酸根（V）。Ce-CTS吸附剂在吸附过程条件下稳定，未观察到吸附剂结构变化或无机填料的浸出。
