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Many physical properties of aqueous N-Methyl pyrrolidone mixtures were determined for molar fraction X NMP ¼ 0.02, 0.05, 0.125, 0.32, 0.37 at different temperatures ranging from 15-65 C. From the result we noticed that the viscosity coefficient was increased with increasing the molar fraction X NMP and reached a maximum value at X NMP ¼ 0.25-0.37, and decreased with temperature. We observed the same relationship of the thermodynamic properties for the mixture at different temperatures and for excess activation function was positive. They reached maximum value at the X NMP ¼ 0.25-0.37. The same relationship was observed for excess dielectric constant. The results were explained according to hydrogen bonding effects and dipole-dipole interactions. This binding is stronger than binding between water molecules which may be let to form a complex at the ORDER REPRINTS molal fraction ratio 2:1 of water-NMP solution. We noticed that an increase in temperature may be let to tighten the interaction between water and NMP.

Both primary and secondary oil dispersions may coexist during coalescence in spherical particulate beds. Therefore, the discussion of capture mechanisms, whatever the drop sizes, will be combined. The coalescence process of drop capture mechanisms will be considered in six types, namely indirect interception, direct interception, inertial impacting, sedimentation, London Van der Waal's forces and diffusion. This approach is convenient because most previous workers have defined these capture mechanisms. Although they have either disagreed as to the mechanisms postulated or found them inapplicable to the specific system under consideration. In this work, theoretical comparison of drop capture mechanisms demonstrated that indirect interception and London Van der Waal's mechanisms are most significant if the drops are >10 m. The diffusion mechanism may become significant for drops <10 m diameter.

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