An electrostatic coalescer for coalescing of a dispersed phase from a continuous phase in an emulsion is presented. The electrostatic coalescer includes at least one inlet for receiving the emulsion; at least one outlet for discharging the emulsion after coalescing the dispersed phase; and at least one electrode disposed between the inlet and the outlet, wherein the electrode is configured to receive an AC voltage/current from a power source. The electrostatic coalescer further includes at least one article disposed between the inlet and the outlet, the article includes a plurality of regions disposed on a surface in a predefined pattern, wherein a portion of the plurality of regions is substantially wetting with respect to the dispersed phase, and a portion of the plurality of regions is substantially non-wetting with respect to the dispersed phase.