Recycling of solvent used in a solvent extraction of petroleum hydrocarbonscontaminated soil.

摘要

The application of water washing technology for recycling an organic compositesolvent consisting of hexane and pentane (4:1; TU-A solvent) was investigatedfor extracting total petroleum hydrocarbons (TPH) from contaminated soil. Theeffects of water volume, water temperature, washing time and initialconcentration of solvent were evaluated using orthogonal experiments followed bysingle factor experiments. Our results showed that the water volume was astatistically significant factor influencing greatly the water washingefficiency. Although less important, the other three factors have all increasedthe efficacy of water washing treatment. Based on a treatment of 20g ofcontaminated soil with a TPH concentration of 140mgg(-1), optimal conditionswere found to be at 40°C, 100mL water, 5min washing time and 660mgg(-1) solvent.Semi-continuous water extraction method showed that the concentration of thecomposite solvent TU-A was reduced below 15mgg(-1) d.w. soil with a recoveryextraction efficiency >97%. This finding suggests that water washing is apromising technology for recycling solvent used in TPH extraction fromcontaminated soils