黄铜矿吸附5-戊基-1,2,4-三唑-3-硫酮的热力学及机理

Thermodynamics and mechanism of 5-pentyl-1,2,4-triazole-3-thione adsorption on chalcopyrite surfaces

以正己酸和氨基硫脲为原料,加热回流条件下得到己酰胺硫脲中间体,该中间体在碱溶液中成环并酸化制得5-戊基-1,2,4-三唑-3-硫酮(PETT),采用红外光谱和核磁共振氢谱及碳谱确认其结构。研究PETT对黄铜矿的浮选性能及其在黄铜矿表面的吸附热力学及机理。研究结果表明:PETT是黄铜矿的优良捕收剂,其吸附于黄铜矿表面的优选p H范围为4.0~9.0,吸附量随着温度的升高而增大,其等温吸附符合Langmuir模型,吸附焓变ΔH为54.27 k J/mol,熵变ΔS为278.82 J/(mol·K),吸附自由能变ΔG为-28.81 k J/mol(298 K)。PETT吸附于黄铜矿表面的过程可能为自发、吸热的单分子层化学吸附。PETT通过其三唑环内氮原子和环外硫原子与黄铜矿表面的铜原子成键而化学吸附于黄铜矿表面。

During refluxing, the intermediate, hexanamide thiourea was prepared by using hexanoic acid and thiosemicarbazide as raw materials. And then the intermediate was cyclized in alkaline solutions, and subsequently acidized to obtain 5-pentyl-1,2,4-triazole-3-thione（PETT）. The structure of PETT was characterized by FTIR, 1 HNMR and 13 CNMR spectra. The flotation performance, adsorption thermodynamics and mechanism of PETT on to chalcopyrite were investigated. The results show that PETT is an excellent collector for chalcopyrite flotation and it prefers to adsorb on to chalcopyrite surfaces at p H 4.0-9.0, and its adsorption amount increases with the increase of temperature. PETT adsorption on to chalcopyrite surfaces is in line with Langmuir mode and the thermodynamic parameters ΔH, ΔS and ΔG（298 K） are 54.27 k J/mol, 278.82 J/（mol·K） and-28.81 k J/mol, respectively. This demonstrates that PETT adsorption is a spontaneous, endothermic and monolayer chemisorption. PETT chemisorbs on to chalcopyrite surfaces through bonding of its nitrogen atoms in the triazole ring and the exocyclic sulfur atom with the surface copper atoms.