Adsorption behaviors and mechanisms of dodecyltrimethyl ammonium chloride and cetyltrimethyl ammonium chloride on illite flotation

Collecting performance and adsorption behaviors and mechanisms of two quaternary ammonium salts, dodecyltrimethyl ammonium chloride (DTAC) and cetyltrimethyl ammonium chloride (CTAC), on illite particles have been investigated through flotation tests, adsorption analysis, zeta potential, FTIR measurements and fluorescence spectroscopy. Adsorption analysis revealed that the adsorbed amount of surfactants on mineral surface increases by increasing the pulp pH or by increasing the length of carbon chains of surfactants. Therefore, at same concentrations, CTAC due to its longer carbon chains has a larger adsorption density on illite surface than DTAC, which was measured by FTIR analysis and zeta potential measurements. As compared to DTAC, CTAC showed much better collecting properties as it has higher I-3/I-1 value and a lower critical micelle concentration (CMC) value, which was analyzed by pyrene fluorescence observations. However, decrease in recovery by CTAC in an alkaline solution was mainly due to the complete adsorption of CTAC molecules on mineral particles, hence, its insufficient concentration in the pulp was unable to stabilize the flotation froth. From the results of flotation behaviors and adsorption mechanisms, it is concluded that CTAC is much more efficient surfactant than DTAC in relation to flotation separation of illite. (C) 2018 Elsevier B.V. All rights reserved.