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- Differential capacity (4)
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Eingeladener Vortrag
- nein (23)
The long-term capacitytime dependence of 1-decanol was measured at the mercury/electrolyte interface for the electrolytes KCl, NaCl, LiBr, and K2SO4, each of concentration 0.1 M, in the temperature range 20 to 50°C and at 35°C for electrolyte concentrations of NaCl in the region 0.05 to 0.4 M. All capacitytime dependences exhibited a slow increase of the capacity after a sudden decrease in the short-term range. The corresponding long-term time dependence of the degree of coverage can be theoretically well described with a first-order surface reaction. The ratios of final equilibrium capacity to minimal capacity can be explained with the formation of hemispherical or bilayer surface micelles from an initial monolayer of perpendicularly adsorbed molecules. A generalized packing parameter that involves the increase or decrease of the head groups' distance due to electrolyte ions or other surfactants was introduced. In the case of bilayers of parallel adsorbed molecules, obviously a new type of transition, which will be discussed in detail, occurs.
A method has been derived to completely recover mineral oil dispersed in water. The method involves three steps: the emulsification of the mineral oil by adding amphiphiles, the breaking of the emulsion by adding salts and the extraction of the mineral oil by a non-polar aprotic solvent. Various amphiphiles and types and concentrations of salts were tested. By using amphiphiles with HLB numbers in the range 4.7 to 40 a complete recovery of the mineral oil could be obtained for a combination of salts Na2SO4 + NaH2PO4 with total ionic strength of 6 mol/L.