Department of Chemistry, Federal University of Lavras, Lavras, Brazil.
Institute of Science and Technology, São Paulo State University, Sorocaba, Brazil.
J Environ Sci Health A Tox Hazard Subst Environ Eng. 2022;57(10):841-851. doi: 10.1080/10934529.2022.2119040. Epub 2022 Sep 6.
The generation of residues containing dyes by industrial sectors has been mobilizing scientists to develop methodologies capable of treating water containing these contaminants. Adsorption is an option to remove these molecules from the aqueous medium and, for this study, the composites between silica and cyclodextrins alpha (α-CDSI) and gamma (γ-CDSI) were used to capture methylene blue. Adsorption was spontaneous for both composites ( < 0) and characterized as exothermic and of a physical nature, with of -17.68 and -12.13 kJ mol for α-CDSI and γ-CDSI, respectively. Adsorption took place over a wide pH range, with an efficiency of approximately 96%, reaching equilibrium at 5 minutes. The adsorption kinetics was described by the pseudo-second-order model ( > 0.999) and the adsorption isotherms showed that the process must occur mainly by dye complexation in the cyclodextrins cavities. The values obtained were 210.8 and 205.2 mg g for α-CDSI and γ-CDSI, respectively; the Sips and Temkin models were the ones that best fit the experimental data. The deposition and interactions of the dye with the adsorbent surface were confirmed by the analysis of the IR spectra. Desorption studies showed that the material maintained its adsorption capacity of around 90% until the fourth adsorption/desorption cycle. Thus, the materials produced showed to efficiently remove methylene blue and that composite reuse is a viable process for application in dye removal.
工业部门产生的含染料残留物一直促使科学家开发能够处理含有这些污染物的水的方法。吸附是从水介质中去除这些分子的一种选择，在这项研究中，使用了二氧化硅和α-环糊精（α-CDSI）和γ-环糊精（γ-CDSI）的复合材料来捕获亚甲基蓝。两种复合材料的吸附都是自发的（ < 0），并表现为放热和物理性质，α-CDSI 和 γ-CDSI 的分别为-17.68 和-12.13 kJ mol。吸附在很宽的 pH 范围内进行，效率约为 96%，在 5 分钟内达到平衡。吸附动力学符合准二级模型（ > 0.999），吸附等温线表明该过程主要通过染料在环糊精空腔中的络合发生。α-CDSI 和 γ-CDSI 的 值分别为 210.8 和 205.2 mg g；Sips 和 Temkin 模型最能拟合实验数据。通过对红外光谱的分析证实了染料在吸附剂表面的沉积和相互作用。解吸研究表明，该材料在第四次吸附/解吸循环之前保持了约 90%的吸附能力。因此，所制备的材料表现出有效地去除亚甲基蓝的能力，并且复合材料的再利用是去除染料的可行过程。
