A study of chloramine removal from water using various granular activated carbons including the effects of pH and temperature

It was determined that the removal of monochloramine from water using activated carbon can be approximated by first order reaction kinetics. Mass transfer is controlled by the rate of reaction and pore diffusion. Several carbons were compared for reaction kinetics at neutral pH. Of these, catalytic bituminous carbons were determined to have kinetics about 1.4 to 1.5 times faster than standard bituminous carbons at a given particle size. Because pore diffusion also affects removal, the 20 x 50 mesh carbons exhibited kinetics about 1.7 to 1.8 times those of the 12 x 40 mesh carbons. The effect of temperature was studied and an activation energy of 10.5 kcal/mol was determined. The influent pH was determined to have a significant impact on reaction kinetics, apparently due to the form of chloramine that predominates at different pH values. Lowering the pH from 7.5 to 4.5 increased the reaction kinetics by a factor of about 3.