Deposition behavior of dissolved black carbon on representative surfaces: Role of molecular conformation

Abstract

To understand the fate of colloidal or dissolved black carbon (DBC) in aquatic systems, a quartz crystal microbalance with dissipation (QCM-D) was applied to investigate deposition and release behaviors of DBC. The results suggested that DBC molecular composition and conformation were critical to the deposition processes on model surfaces, which were controlled by not only the classic Derjaguine-Landaue-Verweye-Overbeek (DLVO) interactions but also non-DLVO forces. The deposition rates of alumina, iron oxide and polyamide surfaces first increased due to the change of conformation and then decreased as the salt concentration increased. Correspondingly, the deposition layers first became more rigid and then got softer with the increase in the ionic strength. Both the pH values and calcium ion had distinctive effects on the deposition behaviors and viscoelastic properties due to their particular roles in DBC surface characteristic and molecular conformation. Overall, these results are meaningful to understand the environmental behaviors of DBC in aquatic systems.