Sorption and desorption of phenanthrene onto iron, copper, and silicon dioxide nanoparticles.
The sorption and desorption of phenanthrene by three engineered nanoparticles including nanosize zerovalent iron (NZVI), copper (NZVC), and silicon dioxide (NSiO2) were investigated. The sorption of phenanthrene onto NSiO2 was linear and reversible due to the hydrophilic properties of NSiO2. In comparison, sorption of phenanthrene onto NZVI and NZVC was nonlinear and irreversible, which was potentially due to the existence of significantly heterogeneous surface energy distribution patterns detected by a standard molecular probe technique. Naphthalene exerted significant competitive sorption with phenanthrene for NZVI and NZVC, and the isotherm of phenanthrene changed from being significantly nonlinear to nearly linear when naphthalene was simultaneously absorbed. A surface adsorption mechanism was proposed to explain the observed sorption and competition of phenanthrene on both NZVI and NZVC. In contrast, no competition was observed for sorption onto NSiO2. The sorption of phenanthrene on all three nanoparticles significantly decreased with increasing pH. The sorption irreversibility of phenanthrene on NZVI and NZVC were significantly enhanced with decreasing pH. A pH-dependent hydrophobic effect and dipole interactions between the charged surface (electron acceptors) and phenanthrene with electron-rich pi systems (electron donors) were proposed to explain the observed pH-dependent sorption.
Fang
Jing
J
State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, P.O. Box 2871, Beijing 100085, China.
Shan
Xiao-quan
XQ
Wen
Bei
B
Lin
Jin-ming
JM
Lu
Xian-cai
XC
Liu
Xian-dong
XD
Owens
Gary
G
D000327:Adsorption; D003300:Copper / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D007501:Iron / Q000737:chemistry*; D046529:Microscopy, Electron, Transmission; D053758:Nanoparticles / Q000737:chemistry* / Q000648:ultrastructure; D009281:Naphthalenes / Q000737:chemistry; D010616:Phenanthrenes / Q000737:chemistry*; D012822:Silicon Dioxide / Q000737:chemistry*; D014961:X-Ray Diffraction
D009281:Naphthalenes; D010616:Phenanthrenes; C031721:naphthalene; C031181:phenanthrene; D012822:Silicon Dioxide; D003300:Copper; D007501:Iron