In this study, cellulose nanocrystals (CNCs) were evaluated as potential adsorbents for the selective adsorption and separation of organic dyes mixtures (methylene blue (MB), with either methyl orange (MO) or rhodamine b (RB) or crystal violet (CV)). The role of surface functional groups on the dye-CNC interaction was examined using pristine and surface-functionalized CNCs, such polydopamine (PD) and melamine–formaldehyde (MF) coated CNCs (PD-CNCs and MF-CNCs respectively). Batch adsorption studies on MB/MO dye mixture showed that pristine CNCs bearing anionic sulfate ester groups exhibited preferential adsorption for MB, with a 85.78% adsorption efficiency. This preferential adsorption was further enhanced in the case of PD-CNCs, which showed 100% adsorption efficiency for MB. Additional studies on MB/RB and MB/CV dye mixtures confirmed that the improved selectivity of PD-CNCs towards MB is associated with the synergistic binding interactions, such as electrostatic attraction, π-π stacking, and hydrogen bonding. MF-CNCs with cationic amine groups displayed selective binding towards MO, an anionic dye. Also, PD-CNCs and MF-CNCs were found to completely separate MB and MO from a diluted MB/MO dye mixture. Isothermal titration calorimetry and dye flocculation experiments confirmed that the selective binding is associated with the surface-functionality of CNCs.

在这项研究中，纤维素纳米晶体（CNCs）被评估为选择性吸附和分离有机染料混合物（亚甲基蓝（MB），甲基橙（MO）或若丹明b（RB）或结晶紫（CV）的潜在吸附剂。 ）。使用原始的和表面功能化的CNCs，例如聚多巴胺（PD）和三聚氰胺-甲醛（MF）涂覆的CNCs（分别为PD-CNC和MF-CNCs），检查了表面官能团在染料-CNC相互作用中的作用。对MB / MO染料混合物的批量吸附研究表明，带有阴离子硫酸酯基团的原始CNC对MB表现出优先吸附，吸附效率为85.78％。在PD-CNC的情况下，这种优先吸附得到了进一步增强，而PD-CNC对MB的吸附效率为100％。对MB / RB和MB / CV染料混合物的其他研究证实，PD-CNC对MB的选择性提高与协同结合相互作用有关，例如静电吸引，π-π堆积和氢键结合。具有阳离子胺基的MF-CNC表现出对MO（一种阴离子染料）的选择性结合。同样，发现PD-CNC和MF-CNC可以从稀释的MB / MO染料混合物中完全分离出MB和MO。等温滴定热法和染料絮凝实验证实，选择性结合与CNCs的表面功能有关。发现PD-CNC和MF-CNC可以将MB和MO从稀释的MB / MO染料混合物中完全分离出来。等温滴定热法和染料絮凝实验证实，选择性结合与CNCs的表面功能有关。发现PD-CNC和MF-CNC可以将MB和MO从稀释的MB / MO染料混合物中完全分离出来。等温滴定热法和染料絮凝实验证实，选择性结合与CNCs的表面功能有关。