Efficient and sustainable separation of oil from oily wastes using acid-base switchable ionic liquid system

Abstract

Oily wastes are the serious environmental hazards in petroleum industry. Solvent extraction has commonly been used to remove oil from these wastes. However, the traditional solvents suffer from challenges such as difficult separation of oil and solvent, and high solvent consumption. Here, oil separation and solvent reuse were well achieved through the phase transition of ionic liquid system (D-230-FA system) between one phase and two phases, which the process procedure was simple. The ionic liquid (D-230-FA) was successfully formed by poly (propylene glycol) bis (2-aminopropyl ether) D-230 and fatty acids, which was demonstrated by 1HNMR and FT-IR. The acid-basic switchability of the D-230-FA system was studied by pH, FT-IR. The process of separating oil based on the D-230-FA system was studied by SEM, infrared spectrophotometry test, Soxhlet extraction and molecular dynamics simulation. The results show that the D-230-FA system exhibited excellent acid-basic switchability, the extraction rate could reach 97.59 % and the residual oil rate in the solvent was less than 0.1495 %. Thus, the acid-base switchable D-230-FA system will be expected to treated as the effective extractant for sustainable separation of oily wastes.