AFM, SEM and EDS characterization of manganese oxide coated ceramic water filtration membranes

Tubular ceramic membranes (molecular weight cut-off, 5 kDa) were coated with manganese oxide nanoparticles. Atomic force microscopy imaging of the coated membranes showed no statistically significant change in the surface roughness or maximum height of the surface features compared with the uncoated membrane. However, scanning electron microscopy imaging showed an increase in grain size with increasing number of coating layers. Energy dispersive X-ray spectroscopy mapping and line scanning showed manganese present throughout the membrane, indicating that either manganese oxide nanoparticles penetrated into the filter or residual Mn2+ ions present in the suspension were sorbed onto the filter and oxidized, forming manganese oxide. The coated membranes were used to treat water containing natural organic matter (NOM) in a hybrid ozonation–membrane water filtration system. Treatment reduced the total organic carbon (TOC) in the water samples by 56%.