The effect of pH on the removal of Mo and BTB by oMA has been studied in our previous work 115]. The results of this study suggest that Mo molecules are not adsorbed through ionic -soi group. In the case of BTB, the high removal percentage of BTB by oMA in acidic solution is due to attractive interaction between the positive surface of OMA and molecular BTB and the strong repulsive interaction between the anionic form of BTB and the negative surface of OMA causes the drastic decrease of removal percentage in the basic solution