Cation-regulated in-situ desorption of octadecylamine hydrochloride from the surface of potassium chloride in high-salt solution

Potassium chloride is an important inorganic product widely used in agriculture, chemical industry, medicine, dyes and other fields. In China, quite a part of KCl produced via flotation technique, using hydrochloride octadecylamine (ODA-H) as the flotation agent. The residue of ODA-H will influence product quality or cause different problems, which have gained much attention. However, recent studies focus on the purification techniques based on dissolution-recrystallization process, significantly increasing production cost and causing practical challenges. Herein, a simple but efficient method was presented for the in-situ desorption of ODA-H from the surface of KCl in high salt system. Results revealed that the removal efficiency of ODA-H can be significantly influenced by cations, especially Li+, which the removal efficiency can increase to 60 %. Importantly, the desorption was verified by in-situ Raman spectrum, further proving the exceptional removal rate by Li+rather than the non-dissolution effects. DFT simulated results manifested the function of Li+, which illustrated the large lattice deformation and the strong adsorption effects, not only in acidic condition but also in neutral system. This study will open a new route for the removal of contaminant from the surface of soluble solid in concentrated salt solution.