Figure 5
Schematic diagram of the interaction forces between the AFM tip and the quartz grain surface.
The top panel shows the van der Waals forces between the tip and the various components in the system: water, quartz grain surface and adsorbed organic matter. The bottom panel shows the various sources of charge in the system, which contribute to the EDL repulsion. Important to note is that both the quartz grain surface and the organic material are negatively charged at low salinity and pH 5.5.
