Mn-doped carbon xerogels as catalyst in the removal of microcystin-LR by water-surface discharge plasma

Abstract

Microcystins (MCs), the most common class of cyanobacterial toxins and emerging drinking water contaminants, are harmful to animal and human health. We report on the effective removal of microcystin-LR (MC-LR) using water surface plasma discharge in the presence of carbon xerogels that have been doped with various levels of manganese (Mn). Mn-doped carbon xerogels were prepared by a sol-gel method and characterized via several techniques: N2 adsorption, X-ray diffraction, X-ray photoelectron spectroscopy and high-resolution transmission electron microscopy. The results indicate that different concentrations of dopant change the texture properties, but that they have no obvious influence on the chemical properties or the surface morphologies of Mn-doped carbon xerogels. Water treatment in which MC-LR was removed using water surface plasma discharge was performed. With the addition of carbon xerogels, the removal rate of MC-LR increased from 75.3% to 90.2% after a 6-min treatment. An oxidation-adsorption kinetic model that produces a good fit to the experimental data is proposed.