乙硫氮在铁闪锌矿表面吸附的电化学行为及机理

Electrochemical adsorption behavior and mechanism of diethyldithiocarbamate on surface of marmatite

采用光谱分析、循环伏安及恒电位阶跃法,研究了乙硫氮(NaD)在铁闪锌矿表面吸附的电化学行为及机理,该机理与浮选电化学的混合电位模型并不一致.在酸性条件下,当电位为0～200 mV时,乙硫氮在铁闪锌矿表面电化学吸附形成双乙硫氮(D2);当电位为410 mV时,乙硫氮与矿物发生电化学反应形成ZnD2和S°,并产生钝化,且表面疏水性强;当电位大于600 mV,电极过程由自腐蚀反应控制.在中性和碱性条件下,铁闪锌矿表面的电极过程主要由自腐蚀阳极溶解控制.随着pH值的增大,表面中间态分别为Fe(OH)D2、Fe(OH)2D和Zn(OH)D,并随电位增大进一步氧化成Zn(OH)2、Fe(OH)3和D2,且矿物表面亲水性强.在开路电位条件下,铁闪锌矿表面存在双乙硫氮和乙硫氮金属盐,但不能有效地附着在电极表面.

The electrochemical adsorption behavior and mechanism of diethyl dithiocarbamate （NaD） on the surface of marmatite, which are different from the mixed potential model of flotation electrochemistry, were studied by spectrum analysis, CA voltammetry and constant potential step. Under acidic condition, the dimer diethyldithiocarbamate （D2） is formed on marmatite through the electrochemical adsorption of diethyl dithiocarbamate at 0 - 200 mV. ZnD2 and SO are formed by electrochemical reaction and result in the passivation at 410 mV, and the surface of marmatite has strong hydrophobicity. The electrode process is controlled by self-corrosive reaction at over 600 inV. Under the condition of the neutral and base, the electrode process of marmatite is basically controlled by the anodlc self-corrosion. With the increasing pH, the intermediates on the surface of marmatite are Fe（OH）D2, Fe（OH）2D, Zn（OH）D, respectively, which will be further oxidized into Zn（OH）2, Fe（OH）3 and D2 with the increase of the potential, and the surface of marmatite has strong hydrophilicity. There exist both dimer D2 and diethyl dithiocarbamate salts on the surface of marmatite at open-circuit potential, which can not effectively adhere on the surface of marmatite.