Cu doped MnO₂/γ-Al₂O₃: a facile and efficient catalyst for the degradation of Na₂S in waste water under ambient conditions

Abstract

A series Cu decorated MnO₂/γ-Al₂O₃ catalysts (Cu load, 1%, 3% and 5%) was fabricated by facile co-impregnation method, and investigated for the catalytic oxidative removal Na₂S in waste water. Compared with MnO₂/γ-Al₂O₃, the catalytic activity and stability of Cu-MnO₂/γ-Al₂O₃, was enhanced by modifying with Cu element. XRD, SEM, BET, H₂-TPR and XPS were carried out to characterize these catalyst. XRD and BET show the Cu successfully decorated on the MnO₂/γ-Al₂O₃, and catalyst’s pristine structure are well maintained. SEM shows that the doped Cu species benefits to the uniform dispersion of Mn species, H₂-TPR suggests that the reodox capacity of Cu decorated catalysts were improved after doping with Cu, and XPS shows that doped Cu produces higher concentration of Mn⁴⁺ and O_ads (surface active oxygen species), also expediting the redox cycling between Mn⁴⁺/Mn³⁺ and the promote the O_ads production, which resulting in the enhancement of redox properties. Hence, 3%Cu-MnO₂/γ-Al₂O₃ catalyst could achieve 97.5% degradation of Na₂S in waste water at room conditions in 2 h, by the help of air, this result is superior to other published work.