Individual and Co Transport Study of Titanium Dioxide NPs and Zinc Oxide NPs in Porous Media

Abstract

The impact of pH and ionic strength on the mobility (individual and co-transport) and deposition kinetics of TiO2 and ZnO NPs in porous media was systematically investigated in this study. Packed column experiments were performed over a series of environmentally relevant ionic strengths with both NaCl (0.1−10 mM) and CaCl2 (0.01–0.1mM) solutions and at pH 5, 7, and 9. The transport of TiO2 NPs at pH 5 was not significantly affected by ZnO NPs in solution. At pH 7, a decrease in TiO2 NP transport was noted with co-existence of ZnO NPs, while at pH 9 an increase in the transport was observed. At pH 5 and 7, the transport of ZnO NPs was decreased when TiO2 NPs was present in the solution, and at pH 9, an increase was noted. The breakthrough curves (BTC) were noted to be sensitive to the solution chemistries; the decrease in the breakthrough plateau with increasing ionic strength was observed under all examined pH (5, 7, and 9). The retention profiles were the inverse of the plateaus of BTCs, as expected from mass balance considerations. Overall, the results from this study suggest that solution chemistries (ionic strength and pH) are likely the key factors that govern the individual and co-transport behavior of TiO2 and ZnO NPs in sand.

Characterization, antibacterial, total antioxidant, scavenging, reducing power and ion chelating activities of green synthesized silver, copper and titanium dioxide nanoparticles using Artemisia haussknechtii leaf extract

“…Cu NPs and Ag NPs contain high atom density facets such as (311) which are known to be highly reactive [34]. Both anatase and rutile forms was concluded from XRD pattern of the green synthesized TiO 2 NPs (Figure 2(c [35]. The crystal sizes of gained Ag, Cu and TiO 2 NPs were estimated respectively to be in the range of 47, 51, 66 nm using Debye-Scherer Equation (1):…”

Fate of TiO2nanoparticles in the environment: a review on the transport and retention behavior in the soil compartment

“…Depending upon the chemical nature of porous media used to perform the experiments, cleaning chemicals may also vary in nature. For example, HCl was used to clean Ottawa sand, 38 glass borosilicate 39 and quartz sand 40,41 whereas DI water was used to clean the dolomite and limestone. 40 Common steps for the cleaning procedure remain the same in both cases.…”

“…In view of the above, experiments were carried out by researchers to study the influence of ZnO NPs on the transport and retention behavior of TiO 2 NPs. 39,41 Jyoti Kumari et. al.…”

“…of medium, etc. [38][39][40][41] Other requirements include a cylindrical glass column to retain the stationary phase, a magnetic stirrer and/or an ultra-sonicator to prepare dispersion of NPs, a syringe or peristaltic pump to pass the NP solution in columns in a controlled manner, a balance for weighing purpose and instruments for detection and characterization (e.g., UV spectrophotometer), etc.…”

“…The transport and retention behavior of TiO 2 NPs has been studied by several researchers in such a simulated soil compartment of different saturated porous media in order to achieve relevant environmental conditions. [38][39][40][41] Selection of these media is based on the fact that the Earth's crust consists of sedimentary rocks of diverse nature like conglomerates, carbonates, sandstones and others. 42 Furthermore, it has been reported that quartz-sand and silica are the most commonly found porous materials in the aquatic environment and therefore studied enormously.…”