Dudek Sebastian, Kołodyńska Dorota
Department of Inorganic Chemistry, Institute of Chemical Sciences, Faculty of Chemistry, Maria Curie-Skłodowska University, pl. Marii Curie-Skłodowskiej 2, 20-031 Lublin, Poland.
Materials (Basel). 2020 Jun 3;13(11):2553. doi: 10.3390/ma13112553.
Modification of a commercial iron oxide ion exchanger (Arsen X) was carried out to enhance the removal of arsenic(V) ions. The modification consisted of the adsorption of lanthanum(III) ions on the Arsen X surface. After adsorption, the material was dried at 313 K to obtain the modified ion exchanger Arsen X-La(III). The modification process itself was tested for optimal pH, kinetics, and equilibrium adsorption isotherm study. Accurate sorbent characteristics were made using, among others, SEM, FTIR, and nitrogen adsorption/desorption isotherms. Then, various tests were carried out to compare the adsorption properties of the modified and unmodified material. It turned out that the tested material was able to completely remove arsenic from an aqueous solution with an initial concentration of up to 50 mg/dm. Without modification, it was not possible to reach the WHO recommended 10 μg/dm arsenic limit even at an initial concentration of 25 mg/dm. Moreover, the maximum sorption capacity increased from 22.37 to 61.97 mg/g after modification (3 times greater than before modification). It is worth noting that the process of removing arsenic on Arsen X-La(III) is fast-equilibrium is reached after about 120 min. Under almost neutral conditions, precipitation and adsorption can be the main mechanisms of As(V) removal. After modification, the removal capacity was enhanced by the co-precipitation and adsorption by exchange of the OH- group with arsenic ions. Such La(III) based adsorbent can be successfully applied in wastewater purification and displays superior performance for removing arsenic.
对一种商用氧化铁离子交换剂（Arsen X）进行了改性，以提高对砷（V）离子的去除效果。改性包括在Arsen X表面吸附镧（III）离子。吸附后，将材料在313 K下干燥，以获得改性离子交换剂Arsen X-La(III)。对改性过程本身进行了最佳pH值、动力学和平衡吸附等温线研究的测试。使用扫描电子显微镜（SEM）、傅里叶变换红外光谱（FTIR）和氮吸附/解吸等温线等方法确定了准确的吸附剂特性。然后，进行了各种测试，以比较改性和未改性材料的吸附性能。结果表明，测试材料能够从初始浓度高达50 mg/dm³的水溶液中完全去除砷。未经改性时，即使初始浓度为25 mg/dm³，也无法达到世界卫生组织推荐的10 μg/dm³的砷限量。此外，改性后最大吸附容量从22.37 mg/g增加到61.97 mg/g（比改性前大三倍）。值得注意的是，在Arsen X-La(III)上去除砷的过程很快——大约120分钟后达到平衡。在几乎中性的条件下，沉淀和吸附可能是去除As(V)的主要机制。改性后，通过共沉淀以及OH⁻基团与砷离子交换的吸附作用，去除能力得到增强。这种基于La(III)的吸附剂可成功应用于废水净化，并在去除砷方面表现出卓越性能。
