Adsorption of N-hydrocinnamoyl-N-phenylhydroxylamine on pure minerals

Abstract

Equilibrium adsorption studies of N-hydrocinnamoyl-N -phenylhydroxylamine (HCNPHA) on galena, sphalerite, pyrite, chalcopyrite and quartz at pH 9 and 10 are reported. All adsorption isotherms followed Langmuir model, however, Freundlich type was observed for quartz. As HC-NPHA is a strong chelating agent, formation of monolayers by chemisorption appeared to be the most probable mechanism of adsorption on the base-metal sulphide minerals. Specific adsorption of HCNPHA on iron containing minerals, namely, chalcopyrite and pyrite, was about three times that on galena and sphalerite, and specific adsorption on quartz was the lowest amongst the minerals studied. Specific adsorptions (in µmol/g) of HCNPHA on the minerals at pH 9 are: sphalerite: 30.5; galena: 26.9; chalcopyrite: 112.3; pyrite: 145.4; quartz: 2.9. Compared to pH 9, specific adsorption of HCNPHA on the minerals decreased at pH 10, indicating hydroxylation of mineral sites due to higher hydroxide ion concentration at pH 10. A spectral-colorimetric procedure was developed for the quantitative estimation of HCNPHA. Due to deprotonation of hydroxamic acids direct estimation using UV absorption was not possible. Hence, complexation of HCNPHA with Fe 3+ was used to develop a purple coloured complex that absorbs in the visible region with λ max = 500 nm. Change in concentration of HC-NPHA was measured from absorbance of the HCNPHAFe 3+ complex at 500 nm. Electronic supplementary materialThe online version of this article (

A novel collector 2-ethyl-2-hexenoic hydroxamic acid: Flotation performance and adsorption mechanism to ilmenite

“…Commonly, the two O atoms in carbonyl and hydroxyl groups of a hydroxamate molecule bond with metal cation to form a five-membered ring structure. The surface complexes of hydroxamic acid and metal species on mineral surface were also reported [8][9][10][11][12]. As a result, hydroxamic acids such as octyl hydroxamic acid (OHA), benzohydroxamic acid and salicylhydroxamic acid have been widely used as collectors for flotation recovery of metal oxide minerals including copper [13], tin [8], iron [14], tungsten [15], and rare earth minerals [9].…”

Separation of Oxidized Pyrrhotite from Fine Fraction Serpentine

“…The shift energies of valence electrons on the surfaces of pyrrhotite (ET = 24 h) and serpentine, before and after treatment with OHA (OHA concentration: 5 × 10 −4 mol/L, pH = 8.0), are shown in Table 5, and the O1s and N1s spectra of pyrrhotite (ET = 24 h) and pyrrhotite (ET = 24 h) treated with OHA (OHA concentration: 5 × 10 −4 mol/L, pH = 8.0) are shown in Figures 7 and 8, respectively. The binding energy of O1s and Fe2p of pyrrhotite (ET = 24 h) underwent a change of 0.15 eV and 0.18 eV after OHA treatment, respectively, which indicated that the chemical environment of Fe and O atoms experienced changes, and OHA was chemically adsorbed on the surface of pyrrhotite (ET = 24 h) [25]. However, the binding energy of the O1s of serpentine had not changed in the presence of OHA.…”

“…Meanwhile, a new peak (398.88 eV) was observed after OHA treatment, as shown in Figure 8, which may correspond to an "O, N" four-ring chelate [30]. The binding energy of O1s and Fe2p of pyrrhotite (ET = 24 h) underwent a change of 0.15 eV and 0.18 eV after OHA treatment, respectively, which indicated that the chemical environment of Fe and O atoms experienced changes, and OHA was chemically adsorbed on the surface of pyrrhotite (ET = 24 h) [25]. However, the binding energy of the O1s of serpentine had not changed in the presence of OHA.…”

“…Hydroxamic acids, R-CO-NHOH (R, alkyl/aryl group), are much weaker acids than the corresponding carboxylic acids, in the identical carbon chain, but possess stronger abilities in selectively chelating metal ions [24]. Hydroxamic acids can chelate with metal cations (e.g., Cu 2+ , Fe 3+ , Al 3+ ) to form hydrophobic metal chelates [24,25], and the chelation reaction for hydroximic acids to metal cation can form an "O, N" four-ring chelate and/or an "O, O" five-ring chelate (the chelate products are shown in Figure 1). Since the tension of the four-ring chelate is relatively high, and the stability is poor, the chelate product is mainly a five-ring chelate.…”