Influence of Clay Particles on the Transport and Retention of Titanium Dioxide Nanoparticles in Quartz Sand

Abstract

This study investigated the influence of two representative suspended clay particles, bentonite and kaolinite, on the transport of titanium dioxide nanoparticles (nTiO2) in saturated quartz sand in both NaCl (1 and 10 mM ionic strength) and CaCl2 solutions (0.1 and 1 mM ionic strength) at pH 7. The breakthrough curves of nTiO2 with bentonite or kaolinite were higher than those without the presence of clay particles in NaCl solutions, indicating that both types of clay particles increased nTiO2 transport in NaCl solutions. Moreover, the enhancement of nTiO2 transport was more significant when bentonite was present in nTiO2 suspensions relative to kaolinite. Similar to NaCl solutions, in CaCl2 solutions, the breakthrough curves of nTiO2 with bentonite were also higher than those without clay particles, while the breakthrough curves of nTiO2 with kaolinite were lower than those without clay particles. Clearly, in CaCl2 solutions, the presence of bentonite in suspensions increased nTiO2 transport, whereas, kaolinite decreased nTiO2 transport in quartz sand. The attachment of nTiO2 onto clay particles (both bentonite and kaolinite) were observed under all experimental conditions. The increased transport of nTiO2 in most experimental conditions (except for kaolinite in CaCl2 solutions) was attributed mainly to the clay-facilitated nTiO2 transport. The straining of larger nTiO2-kaolinite clusters yet contributed to the decreased transport (enhanced retention) of nTiO2 in divalent CaCl2 solutions when kaolinite particles were copresent in suspensions.

Influence of clay particles on Al2O3 and TiO2 nanoparticles transport and retention through limestone porous media: measurements and mechanisms

“…They found that the mobility of TiO 2 was significantly reduced through soil columns especially in those porous media with higher concentrations of clay minerals. In contrast, Cai et al (2014) found that the presence of suspended clay particles (i.e., bentonite and kaolinite) facilitated the mobility of TiO 2 -NPs through quartz sand porous media.…”

“…Presence of clay particles in porous media is another influential parameter on NPs transport (Schroth and Sposito 1997;Vasiliadou and Chrysikopoulos 2011;Syngouna and Chrysikopoulos 2013;Cai et al 2014). Clay particles are the most abundant inorganic colloids in natural aquatic systems (Cai et al 2014) and there are approximately thirty different types (Wilson et al 2014).…”

“…Clay particles are the most abundant inorganic colloids in natural aquatic systems (Cai et al 2014) and there are approximately thirty different types (Wilson et al 2014). Kaolinite, montmorillonite, illite, and chlorite are the most common clay minerals which are ubiquitously found in the subsurface environment (Wilson et al 2014).…”

“…Other clay types are those composed of a mixture of these four clays (Jiang 2012). Clay particles have a high potential to interact with other (bio) colloids and could serve as carriers of colloids due to their surface charge heterogeneity (Schroth and Sposito 1997;Vasiliadou and Chrysikopoulos 2011;Syngouna and Chrysikopoulos 2013;Cai et al 2014). Depending on the physicochemical conditions in the porous media, clay particles may facilitate or hinder the mobility of colloids in a study by Yang et al (2012), they found that the presence of bentonite in suspensions significantly reduced the transport of bacteria in the quartz sand porous media while Abdel-Fattah et al (2013) observed that the plutonium colloids transport was facilitated though subsurface soil by presence of smectite clay.…”

Heteroaggregation of engineered nanoparticles and kaolin clays in aqueous environments

“…For example, Liang et al (2013) studied the transport of Ag NPs and their interaction with clay particles in soils, and Cai et al (2014) discussed the combined effects of IS and clay particles on the transport of TiO 2 NPs in quartz sand. These studies mainly focused on the effect of pH, IS and clay particles, but some studies show that NOM also plays an important role in the stability of NPs, such as stabilization due to the adsorption of NOM, or enhanced coagulation due to the bridging effect of NOM (Chen and Elimelech, 2007a;Mohd Omar et al, 2014;Zhu et al, 2014).…”