Influence of excess KMnO4 on the adsorption of powdered activated carbon

Abstract The effects of KMnO 4 or powdered activated carbon (PAC) treatment and a combination of these treatments on the removal of natural organic matter (NOM) have been investigated in this research. The experiments were carried out using two processes: Process 1: organic matter oxidized by KMnO 4 (from 0 to 8 mg L −1 ), and then adsorbed onto PAC, and Process 2: PAC oxidized by KMnO 4 (from 0 to 2 mg L −1 ) before the organic matter was adsorbed onto PAC in raw water. The results showed that both processes had acceptable organic matter removals, that is, the COD Mn reduction was more than 18% and the UV 254 reduced by more than 25%, respectively, at a KMnO 4 concentration of 2 mg L −1 and PAC at 30 mg L −1 . However, the organic matter characteristics were obviously different during the two processes. In Process 2, although the EEM picture exhibited lower fluorescence in the humic-like and fulvic-like regions than it did in Process 1, it was not correlative with the decrease of COD Mn and UV 254 , which was assumed that KMnO 4 oxidation altered the structure of some organic matter with a transformation to other structures with high fluorescence intensity in the two regions. Compared to the original PAC, KMnO 4 oxidation did not change the PAC surface chemical and physical characteristics obviously according to nitrogen gas adsorption and FTIR spectral analysis. The results indicate that KMnO 4 oxidation had little influence on the PAC characteristics, whereas the characteristics of the NOM were changed significantly.