Surface spectroscopic study of the adsorption of Ni(II) on pyrite and arsenopyrite at pH 10

✍ Scribed by Hacquard, Elodie; Bessière, Jacques; Alnot, Marc; Ehrhardt, Jean Jacques

• Publisher: John Wiley and Sons
• Year: 1999
• Tongue: English
• Weight: 216 KB
• Volume: 27
• Category: Article
• ISSN: 0142-2421
• DOI: 10.1002/(sici)1096-9918(199909)27:9<849::aid-sia649>3.0.co;2-w

✦ Synopsis

The sorption mechanism of Ni(II) on pyrite (FeS 2 ) and on arsenopyrite (FeAsS) has been investigated at pH 10, using complementary methods for surface characterization such as x-ray photoelectron spectroscopy (XPS), Fourier transform mass spectrometry (FTMS), high-frequency dielectric measurements and electrophoretic mobility measurements. At this pH, the surfaces of the minerals are rapidly covered by an oxidation layer composed mainly of Fe(III) oxides on FeS 2 and Fe(III) arsenite and arsenate on FeAsS and presenting negative zeta potentials of -40 and -60 mV, respectively. The first step of the interaction with Ni(II) is the formation of a hydroxylated surface complex through proton exchange with the surface hydroxyl groups ( Fe-OH). Then, electrostatic interactions between colloidal Ni(II) and the surface produce a heterogeneous coating of an average thickness of a few nanometres. This film inhibits significantly the oxidation by H 2 O 2 of these two minerals, particularly FeAsS.