Liquid Carrier

The effect of additives in water (surfactant, ionic strength and viscosifying agents) will be considered here.

Surfactant Colloids must be stabilized sterically and/or electrostatically. The surfactants are either bonded or adsorbed on the particles; in the latter case, a part passes in the dispersing phase when dilution takes place (for injection and during the elution) so that flocculation can occur. Moreover, experiments with packed columns have shown that surfactants play a role in elution. Silebi observed a decrease of Rf when concentration is increased, but no change in the slope of log D versus AV. This is shown in Figure 5, for RF at various amounts of sodium dodecyl sulfate (mmol L-1) in the presence of 0.2 mmolL-1 NaCl.

Sodium dodecyl sulfate is frequently used below or above its critical micellar concentration (2.5 gL-1). This agent provides wettability of beads and ensures a low ionic strength (0.01). This favours higher RF, better elution and increased resolution. The effect is greater for larger particle sizes. Other work has found that nonionic surfactants lead to higher RF than

1.10

1.10

50 150 250 350 450

Diameter (nm)

Figure 5 Effect of surfactant (SDS) on RF, in the presence of NaCl 0.2 mmol L~1. Open circles, 0.13 mmol L~1; open squares, 0.26 mmol L~1; open triangles, 0.52 mmol L~1; filled circles, 1.08 mmol L~1. (Adapted with permission from results of Silebi CA and MacHugh J (1978) In: Becher P and Yudenfreund MN (eds) Emulsions, Lattices and Dispersions, pp. 155-173. New York: Dekker.

50 150 250 350 450

Diameter (nm)

Figure 5 Effect of surfactant (SDS) on RF, in the presence of NaCl 0.2 mmol L~1. Open circles, 0.13 mmol L~1; open squares, 0.26 mmol L~1; open triangles, 0.52 mmol L~1; filled circles, 1.08 mmol L~1. (Adapted with permission from results of Silebi CA and MacHugh J (1978) In: Becher P and Yudenfreund MN (eds) Emulsions, Lattices and Dispersions, pp. 155-173. New York: Dekker.

Solar Panel Basics

Solar Panel Basics

Global warming is a huge problem which will significantly affect every country in the world. Many people all over the world are trying to do whatever they can to help combat the effects of global warming. One of the ways that people can fight global warming is to reduce their dependence on non-renewable energy sources like oil and petroleum based products.

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