Diploma Thesis Defense by Mr. Alexandros Arnogiannakis
Thesis Title: «Ιnteraction of titanium dioxide nanoparticles with montmorillonite»
Friday 12 June 2020, at: 13:45 – 15:30 Link: https://www.epresence.gr/conferences
Examination Committee
- Professor Constantinos Chrysikopoulos (advisor)
- Professor George Karatzas
- Professor Ioannis Tsanis
Abstract
Titanium dioxide nanoparticles (nTiO2) are widely used in industrial and consumer products. The accurate detection, characterization of nTiO2 is important for understanding the specific properties, behaviors, fate, and potential risk of nTiO2 they pose to the environment. Specifically, it is highly possible that, due to its increasing production, it will end up in the subsoils, which are mainly composed by fossils and clays, one of which is montmorillonite (MMT). Τhis particular thesis studies, the interaction between nTiO2 and MMT colloids, in kinetic batch and packed column experiments
All experiments have examined the same parameters, three different values of concentration, C, (50, 100, 200 mg/L) and four different values of Ionic Strength, Is, (1, 25, 50, 100mM), whereas the values of pH and temperature were stable at 7 and 25oC respectively. Subsequently, column packed experiments took place, for pointing out the characteristics of the transport of nTiO2 and MMT colloids separately along with characteristics of their transport by advection. For the simulation of subsoil, quartz sand is used, since it is found on the majority of subsoil formations, while prior to each experiment, measurements of their ζ-potential and hydrodynamic diameter, dp, were taking place.
Afterwards, on the one hand, static batch experiments were conducted, in which the interaction between nTiO2 and MMT colloids was studied separately, under static conditions, as well as the adsorption kinetics of nTiO2 onto MMT colloids and the inverse. In accordance with the results, great amounts of nTiO2 are adsorbed onto MMT colloids, while at the same time the change of Ionic Strength enables for greater values of adsorption in contrast with the change of concentration.
On the other hand, dynamic batch experiments were conducted, in which the adsorption kinetic of nTiO2 onto sand and MMT colloid onto sand, were studied. Furthermore, the adsorption kinetic of nTiO2 onto sand with the presence of MMT colloids and the adsorption of MMT colloids onto sand with the presence of nTiO2 were investigated. It is worth noting that, it is not clear whether any of the parameters were able to intensify the adsorption kinetics. To conclude, the column packed experiments proofed that the presence of MMT colloids increases the transportation of nTiO2 and decreases the final quantity of nTiO2 that is detained in quartz sand.
