Ethyl xanthate collector interaction with precipitated iron and copper hydroxides – Experiments and DFT simulations

• Ethyl xanthate (EX) interaction with iron/copper hydroxides at basic pH was studied.
• Stronger interaction of EX with solvated copper hydroxides than iron hydroxides.
• No affinity of EX to interact with negatively-charged iron hydroxide complexes.
• Fe(OH)4− presence in electrical double layer lowers EX affinity to iron hydroxides.

The interaction of ethyl xanthate collector with precipitated iron and copper hydroxides at alkaline pH was studied both experimentally and through DFT simulations. Experiments revealed that the collector had lesser affinity for interaction with iron hydroxide precipitates compared with copper hydroxide. In an attempt to comprehend the factors in favor of the higher interactions between ethyl xanthate and copper hydroxides, quantum mechanical simulations using density functional theory (DFT) have been carried out. The DFT simulation results confirmed that the interaction of ethyl xanthate with solvated copper hydroxides was more energetically favorable than with iron hydroxides. The simulations also showed that negatively-charged iron hydroxide complexes, should they arise at alkaline pH in the electrical double layer surrounding iron hydroxide precipitates, bring about no affinity vis-à-vis ethyl xanthate collector and quite contrarily, their formation and adsorption on the precipitate surface could inhibit the collector adsorption.

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