Gago Diana, Chagas Ricardo, Ferreira Luísa M, Velizarov Svetlozar, Coelhoso Isabel
LAQV-REQUIMTE, NOVA School of Science and Technology, 2829-516 Caparica, Portugal.
i3N/CENIMAT, Department of Materials Science, NOVA School of Science and Technology, 2829-516 Caparica, Portugal.
Membranes (Basel). 2020 Jan 10;10(1):13. doi: 10.3390/membranes10010013.
A novel cellulose-based cross-linked polymer, dicarboxymethyl cellulose (DCMC), has been synthesized and used for methylene blue (MB) removal. Inductively coupled plasma atomic emission spectrometry (ICP-AES), Fourier-transform infrared spectroscopy (FTIR), nitrogen porosimetry, and optical microscopy were employed to characterize the structure of the cellulose-based adsorbent. The number of carboxylate groups per gram of polymer (CG) was calculated with sodium content determined by ICP-AES. Systematic equilibrium and kinetic adsorption studies were performed to assess the polymer suitability for dye removal. The effect of pH on its adsorption capacity was also studied and the equilibrium adsorption data was analyzed using Langmuir, Freundlich, and Sips isotherms. At pH = 3, the adsorption isotherms followed the Langmuir model with a maximum adsorption capacity of 887.6 mg/g. At pH = 6.4, the adsorption isotherms produced S-shape curves and were best fitted with the Sips model. The maximum MB uptake increased to 1354.6 mg/g. Pseudo first-order and second-order models were used to fit the kinetic data. A pseudo second-order kinetic model provided the best correlation for the adsorption of MB onto DCMC. Adsorption coupled with membrane filtration achieved 95% methylene blue removal and DCMC can be successfully regenerated and reused in consecutive experiments.
一种新型的基于纤维素的交联聚合物，二羧甲基纤维素（DCMC），已被合成并用于去除亚甲基蓝（MB）。采用电感耦合等离子体原子发射光谱法（ICP-AES）、傅里叶变换红外光谱法（FTIR）、氮孔隙率测定法和光学显微镜对纤维素基吸附剂的结构进行了表征。通过ICP-AES测定的钠含量计算每克聚合物中羧酸盐基团的数量（CG）。进行了系统的平衡和动力学吸附研究，以评估该聚合物对染料去除的适用性。还研究了pH对其吸附容量的影响，并使用朗缪尔、弗伦德利希和西普斯等温线对平衡吸附数据进行了分析。在pH = 3时，吸附等温线符合朗缪尔模型，最大吸附容量为887.6 mg/g。在pH = 6.4时，吸附等温线呈现S形曲线，最适合用西普斯模型拟合。最大MB吸附量增加到1354.6 mg/g。采用伪一级和二级模型对动力学数据进行拟合。伪二级动力学模型对MB在DCMC上的吸附提供了最佳相关性。吸附与膜过滤相结合实现了95%的亚甲基蓝去除率，并且DCMC可以在连续实验中成功再生和重复使用。
