Effect of different-sized colloids on the transport and deposition of titanium dioxide nanoparticles in quartz sand. (January 2016)

• Record Type: Journal Article
• Authors: Cai, Li; Peng, Shengnan; Wu, Dan; Tong, Meiping
• Is Part Of: Environmental pollution. Volume 208:Part B(2016)
• Page Start: 637
• Page End: 644
• Publication Date: 2016-01
• Subjects: nTiO2 -- Different-sized colloids -- Microspheres -- Bacteria -- Quartz sand; Pollution -- Periodicals; Pollution -- Environmental aspects -- Periodicals; Environmental Pollution -- Periodicals; Pollution -- Périodiques; Pollution -- Aspect de l'environnement -- Périodiques; Pollution -- Effets physiologiques -- Périodiques; Pollution; Pollution -- Environmental aspects; Periodicals; Electronic journals; 363.73
• DOI: 10.1016/j.envpol.2015.10.040
• Languages: English
• ISSNs: 0269-7491

Abstract

Abstract: Colloids (non-biological and biological) with different sizes are ubiquitous in natural environment. The investigations regarding the influence of different-sized colloids on the transport and deposition behaviors of engineered-nanoparticles in porous media yet are still largely lacking. This study investigated the effects of different-sized non-biological and biological colloids on the transport of titanium dioxide nanoparticles ( n TiO2 ) in quartz sand under both electrostatically favorable and unfavorable conditions. Fluorescent carboxylate-modified polystyrene latex microspheres (CML) with sizes of 0.2–2 μm were utilized as model non-biological colloids, while Gram-negative Escherichia coli (∼1 μm) and Gram-positive Bacillus subtilis (∼2 μm) were employed as model biological colloids. Under the examined solution conditions, both breakthrough curves and retained profiles of n TiO2 with different-sized CML particles/bacteria were similar as those without colloids under favorable conditions, indicating that the copresence of model colloids in suspensions had negligible effects on the transport and deposition of n TiO2 under favorable conditions. In contrast, higher breakthrough curves and lower retained profiles of n TiO2 with CML particles/bacteria relative to those without copresent colloids were observed under unfavorable conditions. Clearly, the copresence of model colloids increased the transport and decreased the deposition of n TiO2 in quartz sand under unfavorable conditions (solution conditions examined in present study). Both competition of deposition sites on quartz sand surfaces and the enhanced stability/dispersion of n TiO2 induced by copresent colloids were found to be responsible for the increased n TiO2 transport with colloids under unfavorable conditions. Moreover, the smallest colloids had the highest coverage on sand surface and most significant dispersion effect on n TiO2, resulting in the greatest n TiO2 transport. Graphical abstract: Highlights: Effect of non-biological and biological colloids on n TiO2 transport was studied. Copresent colloids did not alter n TiO2 transport under favorable conditions. Copresent colloids increased n TiO2 transport under unfavorable conditions. Competition for deposition sites and repulsion by CML increased n TiO2 transport. Smallest CML had most significant competition and dispersion effect on n TiO2 . Abstract : Different-sized non-biological and biological colloids did not affect n TiO2 transport under favorable conditions, whereas, they increased n TiO2 transport under unfavorable conditions.