Liu Hongyu, Chang Yunkang, Li Yuhuan, Cao Chengsong, Li Rui
School of Biological Science, Jining Medical University, No. 669 Xueyuan Road, Donggang District, Rizhao 276826, China.
Molecules. 2024 Jan 28;29(3):619. doi: 10.3390/molecules29030619.
To develop a cost-effective method for the effective removal of reactive brilliant blue KN-R (RBB KN-R) from wastewater, we investigated the interactions between RBB KN-R and three cationic surfactants with different alkyl chain lengths, namely dodecyltrimethylammonium bromide (DTAB), tetradecyltrimethylammonium bromide (TTAB), and cetyltrimethylammonium bromide (CTAB). Employing a conductivity analysis, surface tension analysis, ultraviolet-visible spectrophotometry, and molecular dynamics simulation, we ascertained that RBB KN-R formed a 1:1 molar ratio dye-surfactant complex with each surfactant through electrostatic attraction. Notably, an augmentation in alkyl chain length correlated with increased binding strength between RBB KN-R and the surfactant. The resulting dye-surfactant complex exhibited heightened surface activity, enabling interactions through hydrophobic forces to generate dye-surfactant aggregates when the molar ratio was below 1:1. Within these mixed aggregates, self-assembly of RBB KN-R molecules occurred, leading to the formation of dye aggregates. Due to the improved hydrophobicity with increased alkyl chain length, TTAB and CTAB could encapsulate dye aggregates within the mixed aggregates, but DTAB could not. The RBB KN-R aggregates tended to distribute on the surface of the RBB KN-R-DTAB mixed aggregates, resulting in low stability. Thus, at a DTAB concentration lower than CMC, insoluble particles readily formed and separated from surfactant aggregates at an RBB KN-R and DTAB molar ratio of 1:4. Analyzing the RBB KN-R precipitate through scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR) and measuring the DTAB concentration in the supernate revealed that, at this molar ratio, all RBB KN-R precipitated from the dye-surfactant mixed solution, with only 7.5 ± 0.5% of DTAB present in the precipitate. Furthermore, the removal ratio of RBB KN-R reached nearly 100% within a pH range of 1.0 to 9.0 and standing time of 6 h. The salt type and concentration did not significantly affect the precipitation process. Therefore, this simultaneous achievement of successful RBB KN-R removal and effective separation from DTAB underscores the efficacy of the proposed approach.
为开发一种经济高效的方法以有效去除废水中的活性艳蓝KN-R（RBB KN-R），我们研究了RBB KN-R与三种不同烷基链长度的阳离子表面活性剂之间的相互作用，这三种表面活性剂分别是十二烷基三甲基溴化铵（DTAB）、十四烷基三甲基溴化铵（TTAB）和十六烷基三甲基溴化铵（CTAB）。通过电导率分析、表面张力分析、紫外可见分光光度法和分子动力学模拟，我们确定RBB KN-R与每种表面活性剂通过静电吸引形成了摩尔比为1:1的染料-表面活性剂复合物。值得注意的是，烷基链长度的增加与RBB KN-R和表面活性剂之间结合强度的增加相关。所得的染料-表面活性剂复合物表现出更高的表面活性，当摩尔比低于1:1时，通过疏水力相互作用产生染料-表面活性剂聚集体。在这些混合聚集体中，RBB KN-R分子发生自组装，导致染料聚集体的形成。由于随着烷基链长度增加疏水性增强，TTAB和CTAB可以将染料聚集体包裹在混合聚集体中，但DTAB不能。RBB KN-R聚集体倾向于分布在RBB KN-R-DTAB混合聚集体的表面，导致稳定性较低。因此，在DTAB浓度低于临界胶束浓度（CMC）时，当RBB KN-R与DTAB的摩尔比为1:4时，不溶性颗粒很容易形成并与表面活性剂聚集体分离。通过扫描电子显微镜（SEM）和傅里叶变换红外光谱（FTIR）分析RBB KN-R沉淀物，并测量上清液中的DTAB浓度，结果表明，在此摩尔比下，所有RBB KN-R都从染料-表面活性剂混合溶液中沉淀出来，沉淀物中仅存在7.5±0.5%的DTAB。此外，在pH值为1.0至9.0且静置时间为6小时的范围内，RBB KN-R的去除率接近100%。盐的类型和浓度对沉淀过程没有显著影响。因此，这种同时成功去除RBB KN-R并有效从DTAB中分离的方法突出了所提出方法的有效性。
