Simple and efficient strategy for α-MnO2/C by in-situ synthesis and its performance for degrading urea process wastewater

A simple and low-cost method for the synthesis of α -MnO 2 /C catalyst was proposed, in which KMnO 4 was reduced in-situ by cellulose in urea solution. The heterogeneous catalytic degradation of urea wastewater were carried out over α -MnO 2 /C. The effect of KMnO 4 -urea solution concentration on the structure and performance of the catalysts was investigated. The results indicate that δ -MnO 2 tends to curl and collapse into tunnel structure of α -MnO 2 as the concentration of KMnO 4 -urea solution increases, leading to α -MnO 2 is evenly distributed on carbon carrier. When the concentration of KMnO 4 -urea solution is appropriate, the catalyst has not only a large specific surface area but also high oxygen vacancy density, which is the key to be able to completely degrade the urea process wastewater. The reaction kinetics show that the catalytic hydrolysis of urea behaves as a pseudo-first-order reaction. A possible catalytic mechanism of urea hydrolysis over α -MnO 2 /C was proposed. In addition, the reusability experiments show that the α -MnO 2 /C catalyst has a good recycling ability.