Quantitative competitive adsorption characteristics of sodium humate and dodecylamine on hematite and quartz surfaces

Competitive adsorption behavior of reagents is of great significance for efficient flotation separation of minerals. Motivated by the surface complex adsorption, surface complexation model (SCM) is an effective approach for quantitative characterization of reagents adsorption behavior. In this study, sodium humate (SH) adsorption and mixed SH and dodecylamine (DDA) competitive adsorption mechanisms onto hematite and quartz were quan-titatively described and predicted using SCM. The model simulation suggested that there are two binding forms (monodentate and bidentate) between the groups on SH and the hematite sites and one (monodentate) with the quartz sites. The adsorption equilibrium constants (logK) of SH were calculated, which are 10.15, 23.34 (for hematite) and 10.41 (for quartz), respectively. In addition, the fitting results indicate that SH is adsorbed on the hematite surface mainly through the bidentate equivalent to Fe2-R(COO)2 site. Furthermore, the successful prediction of adsorption and surface potential at pH system were performed to verify the reliability of the model. Quantitative analysis of mixed SH and DDA interactions with mineral surfaces will elucidate and predict the reagents competitive adsorption behavior, which can also provide reliable data and parameters for surface complexation databases for surface complexation. Meanwhile, this finding provides valuable insights for the flotation of minerals, which enables their selective separation efficiency to be modulated and optimized.