Influence of prechlorination on powdered activated carbon adsorption of 2-MIB from water

The affecting factors of combining prechlorination with PAC to remove taste and odor compound, 2-methyliosborneol (2-MIB), were investigated. Results indicate that the concentrations of 2-MIB in drinking water change a little after preclorination, but the effect of residual chlorine on PAC adsorption of 2-MIB is substantial. Isothermal absorption curve is greatly affected by the presence of residual chlorine. The kinetic adsorption process of PAC to 2-MIB follows the isothermal equation of Freundich. The PAC adsorption of 2-MIB shows that the amount of PAC adsorption of 2-MIB decreases with the increase of residual chlorine, thus the adsorption capacity of PAC to 2-MIB is reduced. Experimental results from Songhua River show that residual chlorine reacts with other organic matters which have competitive effect on PAC adsorption of 2-MIB. The characterizations of PAC before and after chlorination show that the specific surface area and pore size have no obvious change. PAC analysis by FTIR indicates that the functional groups are changed. Oxygen functional groups of PAC, such as carboxyl and hydroxyl, are greatly increased after chlorination, which have resulted in the decrease of adsorption capacity of PAC to 2-MIB. The main reason for the reduction in the adsorption of 2-MIB in the presence of residual chlorine might be attributed to that chorine oxidizes PAC and changes the surface characteristics of PAC, which results in reduction of adsorption capacity of PAC to 2-MIB and the desorpion of the absorbed 2-MIB into water.