Electrochemical oxidation behavior and surface phase composition of Cu2+-activated arsenopyrite

The electrochemical oxidation behavior of Cu2+-activated arsenopyrite in butyl xanthate (BX) solution at pH=9.2 was investigated. The results show that, at the potential value (φ) of 0.15 V (A1 oxidation peak), the surface of the arsenopyrite predominantly experiences the oxidation of Fe2+ to Fe(OH)3, while arsenic is oxidized to form As(Ⅲ)-O(AsO−2 ). When the φ value is 0.38 V (A2 oxidation peak), the primary process is the oxidation of As(Ⅲ)-O to As(Ⅴ)-O, leading to the formation of HAsO24−. At this stage, copper is predominantly present on the arsenopyrite surface in the form of Cu(Ⅰ)-S (Cu2S). Notably, when the oxidation φ reaches 0.45 V, the binding energy values of Cu 2p3/2 and Cu 2p1/2 shift by 0.8 eV and 1.7 eV, respectively, indicating a transition from Cu2S to CuS. A new S 2p2/3 peak appears at 163.9 eV in the S 2p spectrum, with a relative intensity increases to 11.2%, which can be attributed to the characteristic peak of bridging sulfur atoms in the BX2 molecule. At this point, the hydrophobicity of the arsenopyrite surface significantly is improved. The density functional theory (DFT) calculations indicate that the adsorption energy of BX2 on the CuS surface (-202.99 kJ/mol) is lower than that on the Cu2S surface (-141.63 kJ/mol), suggesting that the adsorption structure formed by BX2 and CuS is more stable. © 2025 Central South University. All rights reserved.