Studies of collectors. Part 12. The flotation of gallium ion with polyphenol-type surfactants

Abstract

Polyphenol-type surfactants bearing 1,2-benzenediol or 1,2,3-trihydroxybenzene units were prepared and applied as flotation collectors for Ga³⁺. The surfactants exhibited a lowering of surface tension at pH 11 (32–47 dyn cm^–1. Gallium(III) was highly floated (80–90%) at pH 3–8 with equimolar C_{n– 1}H_{2n– 1}C(O)C₆H₃(OH)₂(n= 8 or 12) or C₇H₁₅C(O)C₆H₂(OH)₃, but not as highly (60%) with C₁₂H₂₅S[CH₂CHC(O)C₆H₃(OH)₂]_4.8(CH₂CHCO₂H)_9.5H. The floatabilities of Ga³⁺ in 1 mol dm^–3 NaOH were 86–99%, those in 3 mol dm^–3 NaOH were 63–67%, and those in 5 mol dm^–3 NaOH were 26–39% by using a six-fold molar excess of C_{n– 1}H_{2n– 1}C(O)C₆H₃(OH)₂(n= 12 or 18). On the other hand, the floatabilities from 1–5 mol dm^–3 NaOH solutions when C_{n– 1}H_{2n– 1}C(O)C₆H₂(OH)₃ was added were nearly constant (58–59% with n= 12 and 31–35% with n= 18). The Ga³⁺ in a Ga³⁺–Al³⁺ mixture was floated selectively at pH 3–5 by using C₇H₁₅C(O)C₆H₃(OH)₂ or C₇H₁₅C(O)C₆H₂(OH)₃. Moreover, the polyphenol-type surfactants in these flotation systems were almost entirely absent (<10^–5 mol dm^–3) from 3–5 mol dm^–3 NaOH solutions and little decomposed.