Surfactant(SAA)adsorption on soil decreases the efficiency of SAA leaching remediation of organically contami-nated soil.The effect of the presence of polycyclic aromatic hydrocarbons(PAHs)on the adsorption of nonionic SAA on lo-ess has rarely been reported.In this paper,the effect of pyrene(PYR)on the adsorption of TX 100 and TW 80 on loess was investigated by using a soil column leaching simulation experiment,and the effects of solution pH and ionic strength on the adsorption were explored.The results showed that the presence of PYR increased the adsorption of loess on TX 100 and TW 80 from 50.70 mg/kg and 32.06 mg/kg without PYR to 54.47 mg/kg and 44.53 mg/kg with PYR,es-pectively;the solution pH had a significant effect on the adsorption of nonionic SAA by loess,and the amount of ad-sorption decreased slowly with the increase of the pH value;and in the studied range of ionic strengths,NaCl concen-tration did not produce a significant effect on the behavior of loess adsorption of nonionic SAA.The fitting parame-ters for adsorption kinetics indicated that the quasi-secondary adsorption kinetic equation was more suitable for de-scribing the adsorption characteristics of TX 100 and TW 80 on loess.The desorption results showed that both TX 100 and TW 80 adsorbed on loess were not strong,and most of the SAA adsorbed on the soil could be removed by washing with deionized water,and the residual amounts of TX 100 and TW 80 in the soil with the presence of PYR were 1.57 mg/kg and 0.65 mg/kg,espectively,and in the soil without the presence of PYR,the residual amounts of both of them were 0.69 mg/kg and 0.46 mg/kg,indicating that the presence of PYR in the soil could effectively in-crease the residue levels of TX 100 and TW 80 on loess,but the effect was not significant.Based on the above results it was concluded that although the presence of PYR increased the adsorption and residue of nonionic SAA on loess,the secondary soil contamination caused by SAA is not obvious due to the low final residue of SAA in the soil,there-fore,the technique of selecting nonionic SAA drenching solution for remediation of hydrophobic organic soils is feasible.
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