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　K-d*　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　308　K.　(C)　2015　Elsevier　B.V.　All　rights　reserved.