Fig. 4
Values for the strength of binding as a function of local environmental conditions. Organic–mineral interactions are affected by ionic strength, ion composition, and pH. a Ionic strength was varied using NaCl electrolyte at pH = 6. Interactions between COO− and either mica or goethite were investigated. The CH3 functional group was used as a control interaction on mica. b The effects of monovalent (NaCl) and divalent (CaCl2) cations were compared using the carboxylic acid functional group and mica at pH 6 at varying ionic strengths. c The effect of binding between carboxylic acid and mica was probed as a function of pH in 10 mM NaCl solution. For each condition, experiments were performed with the same AFM tip for reproducibility. Rupture forces were measured at loading rates of 3.5 × 10−9 N/s. Values are represented as mean ± 1 standard deviation
