Preparation of composite switchable water with hydrophobic tertiary amine for washing oil sands

Abstract

In this article, the composite switchable water was prepared with hydrophobic tertiary amine and switchable water, which provides a new method for washing oil sands. Firstly, pH and 1HNMR were used to demonstrate that N,N-diethylethanolamine (DEEA) with the excellent CO2 response could be treated as potential switchable water. In addition, N,N-dimethylaniline (DMA) was chosen as a suitable hydrophobic tertiary amine, because DMA is a more steady molecular state than DEEA at the same pH. Then, the composite switchable water (DMA + DEEA(aq)) was prepared with DMA and DEEA solutions. There was the possible presence of inductive effect between DMA and DEEA detected by 1HNRM and it was also found that DEEA reduced the surface tension. Next, the CO2-triggered switchable behavior of the composite switchable water has been demonstrated by pH and conductivity. Finally, a practical application of washing oil sands with the composite switchable water was accomplished. The results showed that the residual oil content of oil sands was reduced to 0.872 wt% from the original 4.64 wt% heavy hydrocarbons (the ratio of DMA in gram to DEEA solutions in mL was 4:15) and both DMA and DEEA solutions also were recycled during the process. In addition, a process for the extraction and separation of simulated oil (kerosene) with the composite switchable water was depicted to further demonstrate the behavior of dissolving oil.