In this study, adsorption efficiencies of trihalomethanes (THMs), disinfection by product (DBPs), by using synthesized hexagonal mesoporous silicates (HMSs) were investigated. HMSs were synthesized and modified surface with single- functional groups (3-aminopropyltriethoxy-, 3-mercaptopropyl- and n-octyldimethyl-) and bi-functional groups of 3-aminopropyltriethoxy- and 3-mercaptopropyl- to investigate the effect of surface functional group on adsorption efficiency and mechanism compared with powder activated carbon (PAC). Kinetics and adsorption isotherm of 4 types of THMs (CHCl₃, CHBrCl₂, CHBr₂Cl and CHBr₃) at low concentration (0-500 µg/L) were investigated at pH 7 and ionic strength 0.01 M. In addition, the effect of molecular structure of THMs on selective adsorption in single and mixed solute solutions was also investigated. For obtained data, 3-mercaptopropyl- grafted HMS had highest adsorption rate and capacity of the four THMs. Adsorption rate of hydrophobic adsorbents was higher than hydrophilic adsorbents. The different molecular structure of THMs affected the adsorption capacity and selectivity. Adsorption capacities of bromohalomethane group on 3-mercaptopropyl- grafted HMS were higher than chlorohalomethane group. The adsorption mechanism is believed to occur via an ion-dipole electrostatic interaction. Moreover, the effect of electrolyte in tap water did not affect the adsorption capacity and selective on organic functionalized HMS whereas that affected the adsorption capacity over PAC.
