title: TiO₂ nanoparticle transport and retention through saturated limestone porous media under various ionic strength conditions.
abstract: 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.
authors.affiliation: Department of Petroleum Engineering, Faculty of Petroleum and Renewable Energy Engineering, Universiti Teknologi Malaysia, 81310 UTM Skudai, Johor Bahru, Malaysia. Electronic address: ali.Esfandiari.bayat@gmail.com.
authors.forename: Ali
authors.initials: A
authors.lastname: Esfandyari Bayat
authors.affiliation: Department of Petroleum Engineering, Faculty of Petroleum and Renewable Energy Engineering, Universiti Teknologi Malaysia, 81310 UTM Skudai, Johor Bahru, Malaysia.
authors.forename: Radzuan
authors.initials: R
authors.lastname: Junin
authors.affiliation: Department of Petroleum Engineering, Faculty of Petroleum and Renewable Energy Engineering, Universiti Teknologi Malaysia, 81310 UTM Skudai, Johor Bahru, Malaysia.
authors.forename: Mohd Nawi
authors.initials: MN
authors.lastname: Derahman
authors.affiliation: Language Academy, Universiti Teknologi Malaysia, 81310 UTM Skudai, Johor Bahru, Malaysia.
authors.forename: Adlina Abdul
authors.initials: AA
authors.lastname: Samad
mesh_terms: D002119:Calcium Carbonate / Q000032:analysis*; D003102:Colloids / Q000737:chemistry; D004563:Electrochemistry; D005374:Filtration; D007700:Kinetics; D015636:Magnesium Chloride / Q000737:chemistry; D053768:Metal Nanoparticles / Q000737:chemistry*; D008855:Microscopy, Electron, Scanning; D009994:Osmolar Concentration; D016062:Porosity; D012965:Sodium Chloride / Q000737:chemistry; D012996:Solutions; D013499:Surface Properties; D013535:Suspensions; D013696:Temperature; D014025:Titanium / Q000737:chemistry*
chemical_list: D003102:Colloids; D012996:Solutions; D013535:Suspensions; D015636:Magnesium Chloride; C009495:titanium dioxide; D012965:Sodium Chloride; D014025:Titanium; D002119:Calcium Carbonate
keywords: Ionic strength; Limestone porous media; Nanoparticle; Stability; Titanium dioxide (TiO(2)); Transport