Figure 11

Surface interaction energy calculated from electrostatic interaction ( V^EL) (i.e., Equation 1) and Lifshitz-van der Waals interaction ( V^LW)(i.e., Equation 5). The V^ELand V^LWvalues are shown individually in the upper figures, whereas the net energy values are shown in the lower figures. The net sum of V^ELand V^LWremains negative throughout the experimental conditions used to derive the z-potential (i.e., circumneutral pH at salinity values indicated on figure) except for the interaction between face and HA-covered edge at very low salinity (S = 0.4 psu). Net negative surface interaction energy would induce aggregation, whereas our observations yielded very little aggregation for S = 3.6 psu and below. On the other hand, aggregation was observed at S = 7.2 psu.