Effects of copper ions on dissolution mechanism of marmatite

铜离子对铁闪锌矿溶解机制的影响

The dissolution mechanism of marmatite in the presence of Cu^(2+)was intensively studied by experiments and density functional theory(DFT) calculations. Leaching experiments showed that Cu^(2+)accelerated marmatite dissolution at high temperatures(above 55 ℃), but the trend was reversed at low temperatures(below 45 ℃), which may be because the reaction mechanism between Cu^(2+)and marmatite changed from surface adsorption to bulk substitution with increasing temperature. The substitution reaction caused more zinc atoms in the marmatite crystal lattice to be released and enhanced the electrochemical reactivity, while the adsorption of copper ions at low temperatures would passivate marmatite, thus inhibiting the reaction process. DFT calculations showed that the energy of the substitution reaction was more negative than that of the adsorption reaction at high temperatures, which further verified the proposed mechanism.

通过实验和密度泛函理论(DFT)模拟计算研究铜离子存在下铁闪锌矿的溶解机制。浸出实验结果表明,铜离子在高温条件下(高于55℃)加速铁闪锌矿的溶解,但在低温条件下(低于45℃)抑制其溶解。导致该现象的原因可能是铜离子与铁闪锌矿间的反应机制随反应温度的升高从表面吸附反应转变为体相取代反应。体相取代反应使铁闪锌矿晶格中更多的锌原子被释放,并且取代反应产物,增强铁闪锌矿表面的电化学反应活性;然而,低温条件下铜离子的吸附会使铁闪锌矿表面钝化,从而阻碍电化学反应的进行。DFT模拟计算表明,高温条件下取代反应的反应能比表面吸附反应能更负,进一步验证了所提出的反应机制。