Transport and aggregation of Al2O3 nanoparticles through saturated limestone under high ionic strength conditions: measurements and mechanisms

• Published in: Journal of nanoparticle research : an interdisciplinary forum for nanoscale science and technology 2014-12, Vol.16 (12), Article 2747
• Main Authors: Bayat, Ali Esfandyari, Junin, Radzuan, Ghadikolaei, Farshad Daraei, Piroozian, Ali
• Format: Article
• Language: English
• Subjects: Applied sciences; Characterization and Evaluation of Materials; Chemistry and Materials Science; Cross-disciplinary physics: materials science; rheology; Electronics; Exact sciences and technology; Inorganic Chemistry; Lasers; Materials Science; Nanocrystalline materials; Nanoscale materials and structures: fabrication and characterization; Nanotechnology; Optical Devices; Optics; Optoelectronic devices; Photonics; Physical Chemistry; Physics; Research Paper; Semiconductor electronics. Microelectronics. Optoelectronics. Solid state devices
• ISSN: 1388-0764; 1572-896X
• DOI: 10.1007/s11051-014-2747-x

Aluminum oxide (Al 2 O 3 ) nanoparticles (NPs) are being utilized in a broad range of applications; thus, noticeable quantities of these particles are being released into the environment. Issues of how and where these particles distribute into the subsurface remain major challenges. In this study, mechanisms governing the transport and aggregation of Al 2 O 3 -NPs (Alpha-40 nm) through saturated limestone porous media under different ionic strength conditions were evaluated. For this aim, 50 mg of Al 2 O 3 -NPs was dispersed in 1 L of different electrolyte solutions including NaCl and CaCl 2 . Ionic strength range was selected from deionized water up to 500 mM. Breakthrough curves in the column effluent were measured by UV–VIS spectrometry. It was found that the presence of NaCl and CaCl 2 in the suspensions led to formation of ion bridges among NPs. Thus, the stability of Al 2 O 3 -NPs significantly declined and NPs started to flocculate and form bigger clusters. Furthermore, ionic strength caused considerable delay in NPs breakthrough in the effluents and reduction of NPs recovery. CaCl 2 compared to NaCl was found more effective in instability and deposition of Al 2 O 3 -NPs. In addition, the obtained results from transport experiments were checked against classical filtration and Derjaguin–Landau–Verwey–Overbeek (DLVO) theories. The results were found to be in agreement with named theories.