title: Adsorption characteristics of haloacetonitriles on functionalized silica-based porous materials in aqueous solution.
abstract: The effect of the surface functional group on the removal and mechanism of dichloroacetonitrile (DCAN) adsorption over silica-based porous materials was evaluated in comparison with powdered activated carbon (PAC). Hexagonal mesoporous silicate (HMS) was synthesized and functionalized by three different types of organosilanes (3-aminopropyltriethoxysilane, 3-mercaptopropyltrimethoxysilane and n-octyldimethysilane). Adsorption kinetics and isotherm models were used to determine the adsorption mechanism. The selective adsorption of five haloacetonitriles (HANs) in the single and mixed solute systems was also studied. The experiments revealed that the surface functional groups of the adsorbents largely affected the DCAN adsorption capacities. 3-Mercaptopropyl-grafted HMS had a high DCAN adsorption capacity compared to PAC. The adsorption mechanism is believed to occur via an ion-dipole electrostatic interaction in which water interference is inevitable at low concentrations of DCAN. In addition, the adsorption of DCAN strongly depended on the pH of the solution as this related to the charge density of the adsorbents. The selective adsorption of the five HANs over PAC was not observed, while the molecular structure of different HANs obviously influenced the adsorption capacity and selectivity over 3-mercaptopropyl-grafted HMS.
authors.affiliation: International Postgraduate Programs in Environmental Management, Graduate School, Chulalongkorn University, Bangkok 10330, Thailand.
authors.forename: Panida
authors.initials: P
authors.lastname: Prarat
authors.forename: Chawalit
authors.initials: C
authors.lastname: Ngamcharussrivichai
authors.forename: Sutha
authors.initials: S
authors.lastname: Khaodhiar
authors.forename: Patiparn
authors.initials: P
authors.lastname: Punyapalakul
mesh_terms: D000097:Acetonitriles / Q000032:analysis* / Q000737:chemistry; D000327:Adsorption; D002623:Chemistry Techniques, Analytical; D004058:Diffusion; D006863:Hydrogen-Ion Concentration; D015394:Molecular Structure; D017646:Organosilicon Compounds; D016062:Porosity; D011437:Propylamines; D012821:Silanes / Q000032:analysis; D012822:Silicon Dioxide / Q000737:chemistry*; D055672:Static Electricity; D014867:Water / Q000737:chemistry*; D014874:Water Pollutants, Chemical / Q000032:analysis*; D018508:Water Purification / Q000379:methods*
chemical_list: D000097:Acetonitriles; D017646:Organosilicon Compounds; D011437:Propylamines; D012821:Silanes; D014874:Water Pollutants, Chemical; D014867:Water; D012822:Silicon Dioxide; C102833:(3-mercaptopropyl)trimethoxysilane; C477625:amino-propyl-triethoxysilane; C032159:acetonitrile