Chinese Journal of Chemical Engineering ›› 2020, Vol. 28 ›› Issue (9): 2294-2300.doi: 10.1016/j.cjche.2020.03.014

• Separation Science and Engineering • Previous Articles     Next Articles

Application of hydrophobic ionic liquid [Bmmim][PF6] in solvent extraction for oily sludge

Lingfu Zhu1, Zuhong Lin1, Jie Tan1, Liyang Hu1, Tingting Zhang1,2   

  1. 1 College of Chemical Engineering, Beijing University of Chemical Technology, Beijing 100029, China;
    2 Centre for Resource and Environmental Research, Beijing University of Chemical Technology, Beijing 100029, China
  • Received:2019-11-24 Revised:2020-03-06 Online:2020-09-28 Published:2020-10-21
  • Contact: Tingting Zhang
  • Supported by:
    The authors acknowledge the financial support from the National Natural Science Foundation of China (Nos. 41807133 and 41977142), the special fund of State Key Joint Laboratory of Environment Simulation and Pollution Control (No. 18K05ESPCT) and the Fundamental Research Funds for the Central Universities (PT1915).

Abstract: In this study, an ionic liquid (IL), 1-butyl-2,3-dimmmethylimidazolium hexafluorophosphate ([Bmmim][PF6]), was used in combination with a composite solvent of methyl acetate and n-heptane to enhance the oil extraction from oily sludge. The oil recovery increased by approximately 15% compared with that of solvent extraction without [Bmmim][PF6] at the optimal ratios of IL to sludge and solvents to sludge, which were at 2:5 (M/M) and 4:1 (V/M), respectively. The saturate, aromatic, resin and asphaltene (SARA) analysis revealed that the recovery of resins and asphaltenes was increased by 14% and 38%, respectively, in the solvent extraction with the addition of [Bmmim][PF6]. [Bmmim][PF6] maintained a good performance after its reuse four times. The addition of [Bmmim][PF6] changed the adhesion forces between oil and soil. The IL-assisted solvent extraction procedure followed the pseudo second-order kinetic model, while the unassisted solvent extraction procedure followed the pseudo first-order kinetic model. The results also demonstrated that [Bmmim][PF6] decreased the solvent consumption by approximately 60% each time. Additionally, [Bmmim][PF6] can be easily separated. The results suggested that enhancing the solvent extraction with this IL is a promising way to recover oil from oily sludge with a higher oil recovery rate and lower organic solvent consumption than those with the unassisted solvent extraction method.

Key words: Oily sludge, Ionic liquid, Solvent extraction, Oil component, Kinetic model