Xu Mengdi, Guo Fangyu, Bao Xicheng, Gui Xiahui, Xing Yaowen, Cao Yijun
Chinese National Engineering Research Center of Coal Preparation and Purification, China University of Mining and Technology, Xuzhou 221116, Jiangsu, China.
School of Chemical Engineering and Technology, China University of Mining and Technology, Xuzhou 221116, Jiangsu, China.
ACS Omega. 2023 Jul 19;8(30):27429-27438. doi: 10.1021/acsomega.3c02863. eCollection 2023 Aug 1.
In the flotation process, the frother, which is typically a surfactant, can be added to the pulp to reduce the surface tension and create stable foam. Currently, the nonionic mixed surfactant is widely employed as the frother for fine coal flotation. In this study, we focused on examining the foam properties of a mixed surfactant comprising short-chain methyl isobutyl carbinol (MIBC) and long-chain polyethylene glycol-1000 (PEG). Analytical techniques such as surface tension measurement, dynamic foam stability measurement, bubble morphology observation, and foam film drainage measurement were used to investigate the foam properties in single and mixed surfactant solution from a macroscopic scale to a microscopic scale. The surface tension results indicated that PEG exhibited higher surface activity than MIBC, and the addition of PEG to MIBC resulted in a significant reduction in solution surface tension. The dynamic foam stability analysis revealed that the incorporation of a small amount of PEG into MIBC solution notably improved foam stability. Furthermore, the addition of PEG to the MIBC solution led to a shift in the bubble size distribution curve from a "double peak" to a "single peak" shape. This shift indicated a substantial reduction in bubble size, indicating an enhanced inhibition of bubble coalescence. Additionally, the liquid film drainage rate was significantly slowed down, and the stability of the liquid film was improved upon the addition of PEG to MIBC. This improvement can be attributed to the synergistic effect of MIBC and PEG molecules adsorbed at the gas-liquid interface. The synergistic effect of mixed MIBC-PEG was due to the additional surface tension gradient created by the difference in surface activity between PEG and MIBC. This surface tension gradient enhances the Marangoni flow of surfactant molecules, thereby improving the self-healing ability of the liquid film and increasing its stability.
在浮选过程中，通常作为表面活性剂的起泡剂可添加到矿浆中以降低表面张力并产生稳定的泡沫。目前，非离子混合表面活性剂被广泛用作细粒煤浮选的起泡剂。在本研究中，我们着重研究了由短链甲基异丁基甲醇（MIBC）和长链聚乙二醇 - 1000（PEG）组成的混合表面活性剂的泡沫性能。使用表面张力测量、动态泡沫稳定性测量、气泡形态观察和泡沫膜排水测量等分析技术，从宏观尺度到微观尺度研究单一和混合表面活性剂溶液中的泡沫性能。表面张力结果表明，PEG表现出比MIBC更高的表面活性，向MIBC中添加PEG导致溶液表面张力显著降低。动态泡沫稳定性分析表明，向MIBC溶液中加入少量PEG可显著提高泡沫稳定性。此外，向MIBC溶液中添加PEG导致气泡尺寸分布曲线从“双峰”形状转变为“单峰”形状。这种转变表明气泡尺寸大幅减小，表明对气泡聚并的抑制作用增强。此外，添加PEG后，液膜排水速率显著减慢，液膜稳定性得到改善。这种改善可归因于吸附在气 - 液界面的MIBC和PEG分子的协同作用。MIBC - PEG混合物的协同作用是由于PEG和MIBC之间表面活性差异产生的额外表面张力梯度。这种表面张力梯度增强了表面活性剂分子的马兰戈尼流，从而提高了液膜的自愈能力并增加了其稳定性。
