5-Heptyl-1,3,4-oxadiazole-2-thione: Synthesis and flotation mechanism to chalcopyrite

In this article, 5-heptyl-1,3,4-oxadiazole-2-thione (HpODT) surfactant was synthesized and originally recommended as a collector for flotation recovery of chalcopyrite, bornite and pyrite. The micro-flotation findings indicated that compared with traditional collectors such as sodium isobutyl xanthate (SIBX) and sodium hexyl xanthate (SHX), HpODT possessed superior flotation affinity to chalcopyrite and bornite, and selectivity against pyrite under alkaline circumstances. After HpODT treatment, the contact angle of chalcopyrite increased, suggesting an improved hydrophobicity of chalcopyrite surfaces. Adsorption thermodynamic and kinetic analyses suggested that chalcopyrite adsorption of HpODT was a spontaneous-endothermic chemisorption process, and the Delta H (change of enthalpy), Delta S (change of entropy), Delta G (change of free energy) and E-a (activation energy) were 21.06 kJ mol(-1), 173.63J mol(-1)K(-1), -30.77 kJ mol(-1) (298K) and 20.19 kJ mol(-1), respectively. The results of zeta potential hinted that HpODT chemisorbed on chalcopyrite surfaces. UV-vis spectra clearly observed that HpODT selectively reacted with Cu+ or Cu2+, not with Fe2+ or Fe3+ ions. FTIR spectra inferred that HpODT-Cu surface complexes were formed on chalcopyrite by reaction of HpODT's C=N-NH-C(=S)-O group with surface copper atoms to build Cu-S and Cu-N bonds. (C) 2017 The Korean Society of Industrial and Engineering Chemistry. Published by Elsevier B.V. All rights reserved.