Frother function–structure relationship: Dependence of CCC95 on HLB and the H-ratio

• Surfactants from four frother families were used to link CCC with HLB.
• To extend to polyethylene glycol alkyl ethers a revised HLB was introduced.
• H-ratio, fraction of hydrophilic component derived from 1H NMR spectrum, could substitute for HLB.
• CCC–H-ratio model permits prediction of bubble size, as illustrated for commercial frothers.

Although the number and diversity of commercial frothers has steadily increased to meet flotation industry demands, frother selection is still mainly empirical. As part of a general structure–property study, the paper presents a correlation between the critical coalescence concentration (CCC95) and H-ratio for surfactants used as flotation frothers. The CCC95 were determined in 0.8 m3 mechanical flotation cell. The H-ratio was a substitution of hydrophile-lipophile balance (HLB) and determined through high resolution proton nuclear magnetic resonance (1H NMR) spectrometry. A large data set, consisting of 45 surfactants from four frother families, was used to develop the correlation. It is shown that the H-ratio can substitute for HLB. The potential of NMR both to identify the frother family and to derive the H-ratio in predicting CCC95 for commercial frothers is discussed.

Example of H-ratio which quantifies the fraction of hydrophilic component in the surfactant molecule from the 1H NMR spectrum could substitute for HLB, in order to predict CCC95 for surfactants.Figure optionsDownload as PowerPoint slide