Degradation of amyl xanthate by manganese dioxide

Amyl xanthate (AX), a widely used reagent in sulfide mineral flotation, has caused serious environmental problems. Manganese dioxides (MnO₂), ubiquitous in natural soils and sediments, are one kind of important oxidant or catalyst in facilitating organic pollutant decomposition. In this study, the oxidative degradation of AX by MnO₂ was investigated in batch experiments. It was found that up to 90% AX was decomposed by MnO₂ in 30 min and the removal efficiency of AX depended strongly on the loading of MnO₂ and pH value in the solution where the reactions closely followed a pseudo-first-order model. The reaction orders with respect to the initial AX concentration, MnO₂ concentration and pH value were 0.4573, 0.2034, and -0.1701, respectively. Coexisting metal ions, such as Mn²⁺, Fe³⁺, Ca²⁺ and Mg²⁺, displayed suppressive effects and the inhibitive capacity of the metal ions followed the order Mn²⁺ > Fe³⁺ > Ca²⁺ > Mg²⁺. However, the effect of humic acid (HA) on reaction rates was significant only at higher concentrations. This study provided meaningful information to elucidate the oxidative degradation of AX by MnO_2.