title: Enhancement of soil retention for phenanthrene in binary cationic gemini and nonionic surfactant mixtures: characterizing two-step adsorption and partition processes through experimental and modeling approaches.
abstract: The enhancement of soil retention for phenanthrene (PHE) through the addition of a binary mixture of cationic gemini (12-2-12) and nonionic surfactants (C12E10) was investigated. The maximum apparent sorption coefficient Kd(*) reached 4247.8 mL/g through the addition of mixed 12-2-12 gemini and C12E10 surfactants, which was markedly higher than the summed individual results in the presence of individual 12-2-12 gemini (1148.6 mL/g) or C12E10 (210.0 mL/g) surfactant. However, the sorption of 12-2-12 gemini was inhibited by the increasing C12E10 dose; and a higher initial 12-2-12 gemini dose showed a higher "desorption" rate. The present study also addressed the sorption behavior of the single 12-2-12 gemini surfactant at the soil/aqueous interface. The sorption isotherm was divided into two steps to elucidate the sorption process; and the sorption schematics were proposed to elaborate the growth of surfactant aggregates corresponding to the various steps of the sorption isotherm. Finally, a two-step adsorption and partition model (TAPM) was developed to simulate the sorption process. Analysis of the equilibrium data indicated that the sorption isotherms of 12-2-12 gemini fitted the TAPM model better. Thermodynamic calculations confirmed that the 12-2-12 gemini sorption at the soil/aqueous interface was spontaneous and exothermic from 288 to 308K.
authors.affiliation: Institute for Energy, Environment and Sustainable Communities, University of Regina, Regina, Saskatchewan S4S 0A2, Canada.
authors.forename: Shan
authors.initials: S
authors.lastname: Zhao
authors.affiliation: Institute for Energy, Environment and Sustainable Communities, University of Regina, Regina, Saskatchewan S4S 0A2, Canada. Electronic address: gordon.huang@uregina.ca.
authors.forename: Gordon
authors.initials: G
authors.lastname: Huang
authors.affiliation: Institute for Energy, Environment and Sustainable Communities, University of Regina, Regina, Saskatchewan S4S 0A2, Canada.
authors.forename: Chunjiang
authors.initials: C
authors.lastname: An
authors.affiliation: Key Laboratory of Beijing for Water Quality Science and Water Environment Recovery Engineering, Beijing University of Technology, Beijing 100124, China.
authors.forename: Jia
authors.initials: J
authors.lastname: Wei
authors.affiliation: Institute for Energy, Environment and Sustainable Communities, University of Regina, Regina, Saskatchewan S4S 0A2, Canada.
authors.forename: Yao
authors.initials: Y
authors.lastname: Yao
mesh_terms: D000327:Adsorption; D002412:Cations; D007477:Ions; D007700:Kinetics; D008823:Micelles; D010616:Phenanthrenes / Q000737:chemistry*; D012987:Soil / Q000737:chemistry*; D012989:Soil Pollutants / Q000737:chemistry; D013501:Surface-Active Agents / Q000737:chemistry*; D013696:Temperature; D013816:Thermodynamics; D014867:Water / Q000737:chemistry; D014873:Water Pollutants / Q000737:chemistry; D014874:Water Pollutants, Chemical / Q000032:analysis
chemical_list: D002412:Cations; D007477:Ions; D008823:Micelles; D010616:Phenanthrenes; D012987:Soil; D012989:Soil Pollutants; D013501:Surface-Active Agents; D014873:Water Pollutants; D014874:Water Pollutants, Chemical; D014867:Water; C031181:phenanthrene
keywords: Binary surfactant mixtures; Enhanced soil retention; Phenanthrene; Soil/water interface; Sorption modeling