Huang Zhuo, Xiang Yuan, Liu Yue-Xiao, Li Guang-Fang, Cao Hui-Qun
Ecological Restoration Technology Center, Changjiang River Scientific Research Institute, No. 23 Huangpu Avenue, Wuhan, People's Republic of China.
Environment Technology Branch, Wuhan Changjiang Kechuang Technology Development Co., Ltd., No. 289 Huangpu Avenue, Wuhan, People's Republic of China.
Heliyon. 2023 Apr 21;9(5):e15669. doi: 10.1016/j.heliyon.2023.e15669. eCollection 2023 May.
Ionic surfactants are easily adsorbed by silt and clay particles, thus affecting the flocculation characteristics and settling behavior. The settling velocity, typical size, Zeta potential and surface tension of silt flocs were measured in the presence of two different kinds of ionic surfactants. The results indicated that the cetyltrimethylammonium bromide (CTAB, a typical cationic surfactant) can dramatically accelerate the settling of slit particles, while the linear alkylbenzene sulfonate (LAS, a typical anionic surfactant) slightly retarded silt sedimentation to some extent. In still water, the representative settling velocity dramatically increased from 0.36 cm s to 0.43 cm s with the increase of CTAB concentration, which increased by more than 20%. Oppositely, the sedimentation rate decreased from 0.36 cm s to 0.33 cm s with the increase of LAS concentration. In flowing water, as the flow rate increased from 0 to 20 cm s and the ionic surfactant concentration increased from 0 to 10 mg L, the sedimentation rate decreased to 57% and 89% in the presence of CTAB and LAS respectively, which was due to an enhanced dispersion of silt particles and a breaking of flocs. The SEM image test shows that the floc particle size increased 1.5 times of the primary particle size under the high CTAB concentration. The flocculation induced by ionic surfactants greatly influences the sediment size as well as the law of settling velocity. The intrinsic influence mechanism was also discussed based on the variations of silt particle properties. This systematic study can be used for further development of flocculation models and particle size distribution of fine-grained soil.
离子型表面活性剂很容易被粉砂和黏土颗粒吸附，从而影响絮凝特性和沉降行为。在两种不同离子型表面活性剂存在的情况下，测量了粉砂絮凝体的沉降速度、典型尺寸、zeta电位和表面张力。结果表明，十六烷基三甲基溴化铵（CTAB，一种典型的阳离子表面活性剂）可显著加速粉砂颗粒的沉降，而直链烷基苯磺酸盐（LAS，一种典型的阴离子表面活性剂）在一定程度上略微延缓了粉砂的沉降。在静水中，随着CTAB浓度的增加，代表性沉降速度从0.36厘米/秒显著增加到0.43厘米/秒，增幅超过20%。相反，随着LAS浓度的增加，沉降速率从0.36厘米/秒降至0.33厘米/秒。在流动水中，随着流速从0增加到20厘米/秒，离子型表面活性剂浓度从0增加到10毫克/升，在CTAB和LAS存在的情况下，沉降速率分别降至57%和89%，这是由于粉砂颗粒的分散增强和絮凝体的破碎。扫描电子显微镜图像测试表明，在高CTAB浓度下，絮凝颗粒尺寸增大到原生颗粒尺寸的1.5倍。离子型表面活性剂引起的絮凝极大地影响了沉积物尺寸以及沉降速度规律。还基于粉砂颗粒性质的变化讨论了内在影响机制。这项系统研究可用于进一步开发絮凝模型和细粒土的粒度分布。
