Ali Esfandyari Bayat

TiO2 nanoparticle transport and retention through saturated limestone porous media under various ionic strength conditions

The impact of ionic strength (from 0.003 to 500mM) and salt type (NaCl vs MgCl2) on transport and retention of titanium dioxide (TiO2) nanoparticles (NPs) in saturated limestone porous media was systematically studied. Vertical columns were packed with limestone grains. The NPs were introduced as a pulse suspended in aqueous solutions and breakthrough curves in the column outlet were generated using an ultraviolent-visible spectrometry. Presence of NaCl and MgCl2 in the suspensions were found to have a significant influence on the electrokinetic properties of the NP aggregates and limestone grains. In NaCl and MgCl2 solutions, the deposition rates of the TiO2-NP aggregates were enhanced with the increase in ionic strength, a trend consistent with traditional Derjaguin-Landau-Verwey-Overbeek (DLVO) theory. Furthermore, the NP aggregates retention increased in the porous media with ionic strength. The presence of salts also caused a considerable delay in the NPs breakthrough time. MgCl2 as compared to NaCl was found to be more effective agent for the deposition and retention of TiO2-NPs. The experimental results followed closely the general trends predicted by the filtration and DLVO calculations. Overall, it was found that TiO2-NP mobility in the limestone porous media depends on ionic strength and salt type.

Transport and retention of engineered Al2O3, TiO2, and SiO2 nanoparticles through various sedimentary rocks.

Engineered aluminum oxide (Al2O3), titanium dioxide (TiO2), and silicon dioxide (SiO2) nanoparticles (NPs) are utilized in a broad range of applications; causing noticeable quantities of these materials to be released into the environment. Issues of how and where these particles are distributed into the subsurface aquatic environment remain as major challenges for those in environmental engineering. In this study, transport and retention of Al2O3, TiO2, and SiO2 NPs through various saturated porous media were investigated. Vertical columns were packed with quartz-sand, limestone, and dolomite grains. The NPs were introduced as a pulse suspended in aqueous solutions and breakthrough curves in the column outlet were generated using an ultraviolet-visible spectrophotometer. It was found that Al2O3 and TiO2 NPs are easily transported through limestone and dolomite porous media whereas NPs recoveries were achieved two times higher than those found in the quartz-sand. The highest and lowest SiO2-NPs recoveries were also achieved from the quartz-sand and limestone columns, respectively. The experimental results closely replicated the general trends predicted by the filtration and DLVO calculations. Overall, NPs mobility through a porous medium was found to be strongly dependent on NP surface charge, NP suspension stability against deposition, and porous medium surface charge and roughness.

Transportation of metal oxide nanoparticles through various porous media for enhanced oil recovery

Recently, considerable attention has been focused on the application of nanoparticles (NPs) for enhanced oil recovery (EOR) purposes. Previous studies on NPs transportation in porous media were conducted in subsurface alluvial zones and sandy soils which did not cover the whole conditions in oil fields. Besides, issues of how and where these materials distribute into the porous media remain major challenges. In this study, mechanisms governing the transport and retention of three metal oxide nanoparticles (NPs) namely Al2O3, TiO2, and SiO2 through limestone and quartz sand porous media were firstly investigated. Then, the named NPs were applied for enhanced oil recovery purpose in these porous media. For this aim, the nanopowders were dispersed in de-ionized water at concentration of 0.005wt%. Vertical columns were packed using limestone, and quartz sand grains in the range of 125 to 175μm. Breakthrough curves in the columns effluents were measured by UV-VIS spectrometry. It was found that the mobility of named NPs through mentioned porous media strongly depends on the NPs surface charge and stability as well as porous media surface charge and roughness. The obtained results from transport experimental tests were found to be in agreement with the classical filtration and Derjaguin-Landau-Verwey-Overbeek (DLVO) theories. Moreover, amount of oil recovery by the NPs was found to have direct relationship with their mobility through porous media where NPs with higher mobilities cause higher oil recoveries.

Evaluation of vapour extraction process and its prospect as an enhanced oil recovery method

The vapour extraction (VAPEX) process is a promising technique to extract heavy oil and bitumen while minimising environmental pollution and capital costs compared to conventional thermal processes. This paper comprehensively reviews the literature on the vapour extraction process to elucidate why VAPEX is not yet operational at the field scale. It was found that unfeasibility of the VAPEX process is mainly attributed to operational issues. A sufficient number of parameters that are associated with these two issues and affect the VAPEX process are evaluated in this paper. [Received: March 11, 2013; Accepted: October 17, 2013]