Description
A Master of Science thesis in Chemical Engineering by Shehzad Liaqat entitled, “Use of Ionic Liquids for Produced Water Treatment”, submitted in December 2021. Thesis advisor is Dr. Taleb Ibrahim. Soft copy is available (Thesis, Completion Certificate, Approval Signatures, and AUS Archives Consent Form).
Abstract
Produced water (PW) has adverse effects on human health and aquatic life. Finding a viable method for the efficient extraction of oil from PW is a challenging task for environmental researchers. In this work, various ionic liquids (ILs) having bis(trifluoromethylsulfonyl)imide (NTf2) anion with different cations such as imidazolium, ammonium, phosphonium, and pyridinium were employed for the removal of oil from PW through liquid-liquid extraction (LLE). Clay-alginate beads loaded with ILs were also applied as adsorbents via the adsorption process. The effect of ILs structure on the removal efficiency of ILs was examined. The effects of several process parameters such as initial concentration of oil, contact time, pH, phase ratio, and temperature on the removal efficiency of ILs were analyzed and optimized. Different characterization such as Fourier transform infrared spectrophotometer (FTIR), scanning electron microscopy (SEM), energy dispersive X-ray (EDX), and thermal gravimetric analysis (TGA) were used to investigate the surface morphology, chemical bond structure and functional group, and thermal stability of the used materials, respectively. Results revealed that 1-decyl-3-methyl-imidazolium bis(trifluoromethylsulfonyl)imide [C10Mim][NTf2] is the best ionic liquid (IL) among the studied ILs at optimum conditions (500 ppm initial oil concentration, 4 min contact time, 8 pH, and at room temperature) with a removal efficiency of 92.8% through LLE. However, clay-alginate-IL beads indicated a removal efficiency of 71.8 % at optimum conditions (600 ppm initial oil concentration, 70 min contact time, 10 pH, and at room temperature) with an adsorption capacity of 431 mg/g. FTIR analysis confirmed the successful chemical bond interaction of oil with IL and beads. SEM analysis verified that beads have a porous and rough surface which is appropriate for the adsorption of oil onto the bead’s surface. TGA analysis provides the thermal degradation profile of clay-alginate-IL. Moreover, the beads used in the adsorption process were regenerated and used up to 4 cycles.