Cleaner and sustainable approach of washing oil sands using CO2-responsive composite switchable water (CSW) with lower volatility

Abstract

Abstract Switchable-Hydrophilicity Solvent (SHS) with high volatility is obstruct to environmental protection and solvent recycling in extraction process. This research aims at providing a cleaner and more sustainable approach of washing oil sands by using the CO2-responsive Composite Switchable Water (CSW). This CSW was prepared by Di-n-propylamine (DPA), N,N-dimethylethanolamine (DMEA) and water. The formation of CSW is attributed to the interaction between DPA and DMEA, which was detected by nuclear magnetic resonance hydrogen spectrum (1HNRM). The different CO2 switchable behaviors of CSW were demonstrated by the variety of conductivity and pH. Although DPA belongs to one of the SHS with high toxicity and volatility, the resulting CSW represents much lower volatility and more stability at room temperature and ambient pressure. The results show that the oil content of oil sands reduces to 2.36 wt% by using CSW with the volume ratio of 2 : 3 between DPA and DMEA aqueous solution (the volume ratio between DMEA and water is 1 : 1). Fourier Transform Infrared Spectroscopy (FT-IR) was used to demonstrate the removing of oil from the sands after being treated with CSW. The reversible change of conductivity shows the recycling ability of CSW. Finally, the economic and environmental value of washing oil sands with CSW was calculated.