Adsorption characteristics of triclosan from aqueous solution onto cetylpyridinium bromide (CPB) modified zeolites

Organo-zeolites (OZs) were prepared by loading cetylpyridinium bromide (CPB) onto natural zeolite (NZ) and were firstly used to remove triclosan (TCS) from aqueous solution. Surface properties and adsorption characteristics of OZs were evaluated in this study. Batch experiments were conducted as a function of contact time, initial TCS concentration, temperature, and pH. The results indicated that NZ surface properties were considerably altered with CPB modification, but its mineral structures were not significantly affected. The adsorption capacities of OZ 0.5, OZ 1.0 and OZ 2.5, prepared with different initial concentrations of CPB, toward TCS at 298 K were greatly enhanced from 0.91 mg g(-1) for NZ to 31.85, 45.25 and 46.95 mg g(-1), respectively. The adsorption equilibrium data of OZs were found to follow the Langmuir isotherm better. The adsorption kinetics data could be well-described by the pseudo-second-order model. Further thermodynamic investigations indicated that TCS adsorption onto OZs was an exothermic and spontaneous process. The TCS adsorption capacities were found to be strongly dependent on the solution pH and the nature of surface charge of OZs, which were a little higher in acidic and neutral pH conditions. The main mechanisms controlling the adsorption of TCS onto OZs with CPB monolayer were presumed to be hydrophobic interaction and hydrogen bonding, while the main mechanisms controlling the adsorption of TCS onto OZs with CPB bilayer may involve organic portioning and electrostatic interaction. As a result, OZs could be used as effective adsorbents for TCS removal from wastewater. (C) 2013 Elsevier B.V. All rights reserved.