Babău Theodora, Ciopec Mihaela, Duteanu Narcis, Negrea Adina, Negrea Petru, Nemeş Nicoleta Sorina, Pascu Bogdan, Mihăilescu Maria, Ianasi Catalin
Faculty of Industrial Chemistry and Environmental Engineering, Politehnica University of Timişoara, Victoriei Square, No. 2, 300006 Timisoara, Romania.
Renewable Energy Research Institute-ICER, Politehnica University of Timisoara, Gavril Musicescu Street, No. 138, 300774 Timisoara, Romania.
Polymers (Basel). 2024 Sep 4;16(17):2512. doi: 10.3390/polym16172512.
The aim of this study was to develop new materials with adsorbent properties that can be used for the adsorption recovery of Au(III) from aqueous solutions. To achieve this result, it is necessary to obtain inexpensive adsorbent materials in a granular form. Concomitantly, these materials must have a high adsorption capacity and selectivity. Other desired properties of these materials include a higher physical resistance, insolubility in water, and materials that can be regenerated or reused. Among the methods applied for the separation, purification, and preconcentration of platinum-group metal ions, adsorption is recognised as one of the most promising methods because of its simplicity, high efficiency, and wide availability. The studies were carried out using three supports: cellulose (CE), chitosan (Chi), and diatomea earth (Diat). These supports were functionalised by impregnation with extractants, using the ultrasound method. The extractants are environmentally friendly and relatively cheap amino acids, which contain in their structure pendant groups with nitrogen and sulphur heteroatoms (aspartic acid-Asp, l-glutamic acid-Glu, valine-Val, DL-cysteine-Cys, or serine-Ser). After preliminary testing from 75 synthesised materials, CE-Cys was chosen for the further recovery of Au(III) ions from aqueous solutions. To highlight the morphology and the functionalisation of the material, we physicochemically characterised the obtained material. Therefore, the analysis of the specific surface and porosity showed that the CE-Cys material has a specific surface of 4.6 m/g, with a porosity of about 3 nm. The FT-IR analysis showed the presence, at a wavelength of 3340 cm, of the specific NH bond vibration for cysteine. At the same time, pHpZc was determined to be 2.8. The kinetic, thermodynamic, and equilibrium studies showed that the pseudo-second-order kinetic model best describes the adsorption process of Au(III) ions on the CE-Cys material. A maximum adsorption capacity of 12.18 mg per gram of the adsorbent material was achieved. It was established that the CE-Cys material can be reused five times with a good recovery degree.
本研究的目的是开发具有吸附性能的新材料，用于从水溶液中吸附回收金（III）。为实现这一目标，有必要获得颗粒状的廉价吸附剂材料。同时，这些材料必须具有高吸附容量和选择性。这些材料的其他理想特性包括更高的物理抗性、在水中的不溶性以及可再生或重复使用的材料。在用于铂族金属离子分离、纯化和预富集的方法中，吸附因其简单、高效和广泛可用性而被认为是最有前途的方法之一。研究使用了三种载体：纤维素（CE）、壳聚糖（Chi）和硅藻土（Diat）。这些载体通过超声法用萃取剂浸渍进行功能化。萃取剂是环境友好且相对便宜的氨基酸，其结构中含有带有氮和硫杂原子的侧基（天冬氨酸 - Asp、L - 谷氨酸 - Glu、缬氨酸 - Val、DL - 半胱氨酸 - Cys或丝氨酸 - Ser）。在对75种合成材料进行初步测试后，选择CE - Cys用于从水溶液中进一步回收金（III）离子。为突出材料的形态和功能化情况，我们对所得材料进行了物理化学表征。因此，比表面积和孔隙率分析表明，CE - Cys材料的比表面积为4.6 m/g，孔隙率约为3 nm。傅里叶变换红外光谱（FT - IR）分析表明，在3340 cm波长处存在半胱氨酸特有的NH键振动。同时，零电荷点（pHpZc）测定为2.8。动力学、热力学和平衡研究表明，准二级动力学模型最能描述金（III）离子在CE - Cys材料上的吸附过程。每克吸附剂材料的最大吸附容量达到12.18 mg。已确定CE - Cys材料可以以良好的回收率重复使用五次。
