热活化胶状黄铁矿去除酸性溶液中的Cd(Ⅱ)

利用XRD和SEM测试方法表征了热活化胶状黄铁矿结构和微观形貌,考察了溶液pH、溶解氧和热活化温度对热活化胶状黄铁矿去除水中Cd(Ⅱ)的影响,并探讨了除Cd(Ⅱ)反应动力学和作用机理。胶状黄铁矿在N_2氛围下650℃热活化5 min可完全分解生成多孔结构化单斜磁黄铁矿(PMPyr)。在pH 2-6的无氧水溶液中PMPyr除cd(Ⅱ)效率均达到88%以上,除Cd(Ⅱ)效率受pH影响较小;PMPyr表面氧化会抑制其与Cd(Ⅱ)的反应。PMPyr除Cd(Ⅱ)动力学可用准二级动力学模型拟合(R~20.9992),结合溶液pH变化趋势、Fe(Ⅱ)和SO_4~(2-)浓度变化推测,PMPyr除Cd(Ⅱ)机理主要是Fe_(1-x)S和CdS溶度积差异推动了PMPyr与Cd(Ⅱ)交换反应,表面络合属于次要作用。

Performance of Thermally Activated Colloidal Pyrite in Removal of Cadmiun(Ⅱ) in Acid Solution

The thermally activated colloidal pyrite was characterized by XRD and SEM. The effect of solution pH, dissolved oxygen， and thermal activation temperatures on the performance of thermally activated colloidal pyrite on removal of Cd(Ⅱ) from aqueous solution were systematically studied. The reactive kinetics and the mechanism of the adsorption of Cd(Ⅱ) on thermally activated colloidal pyrite were also discussed. Colloidal pyrite was decomposed into Porous Monoclinic Pyrrhotite (PMPyr) after thermal activation at 650℃ for 5 minutes in a muffle furnace (nitrogen atmosphere). The removal efficiency of Cd(Ⅱ) by PMPyr in the solution of no dissolved oxy gen was above 88% at pH 2~6, suggesting that the removal efficiency of Cd(II) was less affected by pH. Moreover, surface oxidation of PMPyr could restrain the interaction between PMPyr and Cd( Ⅱ). The kinetic adsorption process was well described by pseudo-second-order model with high correlation coefficient (R2> 0.9992). The influence of pH and change of concentration of Fe (Ⅱ) and SO42- showed that the adsorption of Cd(Ⅱ) on PMPyr was mainly dominated by ion exchange and surface complexation.