Surface charge negative

If the surfactant is anionic (negative ion) and if S is a mineral surface charged negatively, the two will repel each other and the surfactant cannot attach itself to 5. As a result, the energy sw remains unchanged and the surfactant acts on the surface tension 7 only. 

The amount of anions adsorbed cannot be directly measured by the depletion in solution. Repulsion of the anions by the high density of negative surface charges (negative adsorption [57—59]) increases the anion concentration in the bulk and reduces the depletion by the (positive) adsorption. 

One potentially powerfiil approach to chemical imaging of oxides is to capitalize on the tip-surface interactions caused by the surface charge induced under electrolyte solutions [189]. The sign and the amount of the charge induced on, for example, an oxide surface under an aqueous solution is detenuined by the pH and ionic strength of the solution, as well as by the isoelectric point (lEP) of the sample. At pH values above the lEP, the charge is negative below this value. 

An additional method for increasing particle size deserves mention. When a precipitate s particles are electrically neutral, they tend to coagulate into larger particles. Surface adsorption of excess lattice ions, however, provides the precipitate s particles with a net positive or negative surface charge. Electrostatic repulsion between the particles prevents them from coagulating into larger particles. 

The ultimate trapping site for a photoelectron is influenced by the high dielectric constant of silver haUde (ca 12.5, 11.15, and 7.15 for AgBr, AgCl, and P-AgI, respectively), the negative surface charge, and relative trap depths. Interior traps located at point defects on dislocation lines are probably not as... 

Surfa.ce (Charge. Inorganic particles have a surface charge in water that is a function of both the particle s character and the pH of the water. Each particle has an isoelectric pH value where the negative and positive charges on the surface just neutralize each other. Isoelectric points for some common inorganic particles are shown in Table 1. 

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