Tailoring Nanoparticle Designs for Cleaning up Oil Sands Process-affected Water

Abstract

Oil sands industry in Canada continuously produces enormous volume of toxic and low-quality oil sands process-affected water (OSPW) as a result of bitumen extraction, upgrading, and transportation. Typically, OSPW are treated by several chemical treatment stages that primarily focus on water recycling at high capital and operating costs with high environmental footprints. In this study, naturally sourced nanoparticles were designed for cleaning up OSPW through effective and combined process. Thus, nanoparticles with tunable properties were developed to generate hybrid filter media, nanoflocculants, and oil spill nanoscavengers. For the case of steam assisted gravity drainage (SAGD) produced water, under ambient conditions, hybrid filter media were manufactured via integrating low percentage (< 5 wt%) of iron hydroxide nanoparticles with walnut shell filter media (WS), in which the iron hydroxide nanoparticles elevated the active surface area for simultaneous removal of total organic carbon (TOC) and silica. For the tailing water, titanomagnetite nanoparticles, naturally known as ironsand, were synthesized uner ambient conditions and grafted with hydrophobically modified polyacrylamide with lauryl sulfate, forming novel nanoflocculant that was applied to flocculate the mature fine tailings (MFT). Furthermore, the bare titanomagnetite nanoparticles were employed for removal of crude oil spills, following our modified ASTM protocol. The results showed that the hybrid filtration media (WS-NPs) removed up to 85% of silica and TOC through the batch experiments. In the column tests WS-NPs significantly improved the breakthrough behavior without reaching pressure drop limitations. The column breakthrough behaviors were successfully described by a dimensionless advection-axial dispersion model, that was able to accurately capture the real breakthrough behavior, indicating the possibility of scaling up the filter using a combined unit that removes silica and TOC simultaneously. Also, flocculation of the MFT suspension with applying 3000 ppm of the optimized nanoflocculants, against 20,000 ppm of commercially anionic polyacrylamide, provided 15 times faster initial settling rate (ISR) and half values of supernatant turbidity, capillary suction time (CST), and specific resistance to filtration (SRF). Interestingly, a gram of our inhouse prepared iron sand nanoparticles removed 38g crude oil, showing outstanding performance toward oil spill removal.