title: Mechanism of p-nitrophenol adsorption from aqueous solution by HDTMA+-pillared montmorillonite--implications for water purification.
abstract: HDTMA+-pillared montmorillonites were obtained by pillaring different amounts of the surfactant hexadecyltrimethylammonium bromide (HDTMAB) into sodium montmorillonite (Na-Mt) in an aqueous solution. The optimum conditions and batch kinetics of sorption of p-nitrophenol from aqueous solutions are reported. The solution pH had a very important effect on the sorption of p-nitrophenol. The maximum p-nitrophenol absorption/adsorption occurs when solution pH (7.15-7.35) is approximately equal to the pKa (7.16) of the p-nitrophenol ion deprotonation reaction. X-ray diffraction analysis showed that surfactant cations had been pillared into the interlayer and the p-nitrophenol affected the arrangement of surfactant. With the increased concentration of surfactant cations, the arrangement of HDTMA+ within the clay interlayer changes and the sorption of p-nitrophenol increases. HDTMA+-pillared montmorillonites are more effective than Na-Mt for the adsorption of p-nitrophenol from aqueous solutions. The Langmuir, Freundlich and dual-mode sorption were tested to fit the sorption isotherms.
authors: Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China.
authors: Qin
authors: Q
authors: Zhou
authors: Hong Ping
authors: HP
authors: He
authors: Jian Xi
authors: JX
authors: Zhu
authors: Wei
authors: W
authors: Shen
authors: Ray L
authors: RL
authors: Frost
authors: Peng
authors: P
authors: Yuan
mesh_terms: D000327:Adsorption; D001546:Bentonite / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D009596:Nitrophenols / Q000737:chemistry*; D000644:Quaternary Ammonium Compounds / Q000737:chemistry*; D012996:Solutions; D013499:Surface Properties; D014874:Water Pollutants, Chemical / Q000737:chemistry*; D018508:Water Purification / Q000379:methods*; D014961:X-Ray Diffraction
chemical_list: D009596:Nitrophenols; D000644:Quaternary Ammonium Compounds; D012996:Solutions; D014874:Water Pollutants, Chemical; C514921:hexadecyltrimethylammoniumchloride; D001546:Bentonite; C024836:4-nitrophenol