Electrical desalting of crude — what type of impurities are removed?\nDuring electrical desalting, the unit primarily removes ______ impurities from crude oil.

Introduction / Context:
Electrical desalters reduce salt and water content of crude before atmospheric distillation to protect equipment and catalysts. Understanding the wetting characteristics of removable impurities clarifies why the process works.

Given Data / Assumptions:

• Crude is mixed with wash water and subjected to a high electric field.
• Water droplets coalesce and separate due to electrostatic forces.

Concept / Approach:
The process targets water-wet (oleophobic) dispersed droplets carrying dissolved inorganic salts and fine hydrophilic solids. The electric field induces droplet dipoles, coalescence, and settling, removing brine and water-wet particulates. Oil-wet (oleophilic) fines tend to remain with the oil phase and are not efficiently removed by electrostatic coalescence alone.

Step-by-Step Solution:

Verification / Alternative check:
Salt removal performance correlates with effective water coalescence, underscoring that water-wet species are captured with the aqueous phase.

Why Other Options Are Wrong:

• Oleophilic impurities do not preferentially report to the aqueous phase.
• Metallic particulates may be removed only if water-wet.

Common Pitfalls:
Under-dosing wash water or using incompatible demulsifiers reduces removal of water-wet impurities.

Final Answer:
Oleophobic (water-wet) impurities