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Difficulty: HardSublimation, Magnetization, and Centrifugation

An industrial wastewater slurry contains suspended micro-fine latex particles, dissolved sodium chloride, and insoluble magnetite (Fe3O4Fe_3O_4) powder. To efficiently recover pure magnetite powder, isolate the micro-fine latex particles, and obtain pure water from the mixture without chemical additives, which sequence of separation techniques should be applied?

  1. Application of a magnetic field to extract magnetite, high-speed centrifugation to sediment latex particles, followed by distillation to recover pure waterAnswer
  2. B
    High-speed centrifugation to separate dissolved sodium chloride, magnetization to remove latex particles, followed by evaporation to recover pure water
  3. C
    Gravity filtration to separate dissolved sodium chloride, sublimation to vaporize magnetite powder, followed by magnetization to isolate latex particles
  4. D
    Sublimation to remove suspended latex particles, gravity filtration to isolate magnetite powder, followed by centrifugation to recover pure water from salt

Answer

Application of a magnetic field to extract magnetite, high-speed centrifugation to sediment latex particles, followed by distillation to recover pure water
Magnetite is ferromagnetic and can be selectively extracted using a magnetic field. Colloidal latex micro-particles do not settle under normal gravity due to thermal agitation (Brownian motion), requiring high-speed centrifugation to force sedimentation based on density. Distillation then vaporizes and condenses water to isolate it from dissolved non-volatile sodium chloride.

Step-by-Step Solution

1
Identify the physical properties of each component in the mixture
Magnetite (Fe3O4Fe_3O_4) is magnetic and insoluble; latex forms a micro-suspended colloid; sodium chloride forms a true aqueous solution; water is the liquid solvent.
Separation techniques must exploit differences in specific physical properties such as magnetism, particle mass/density, and boiling point.
2
Apply magnetization first
Insoluble magnetic Fe3O4Fe_3O_4 is attracted and cleanly separated from the liquid slurry.
Magnetic separation isolates the strongly magnetic solid without altering or contaminating liquid phase components.
3
Apply high-speed centrifugation to the remaining mixture
Suspended colloidal latex particles sediment rapidly out of the liquid phase.
Colloidal particles remain in suspension under normal gravity due to Brownian motion, but high centrifugal force forces them to settle based on density differences.
4
Perform distillation on the remaining true solution
Water evaporates and condenses as pure distillate while sodium chloride remains in the distillation flask.
Distillation separates volatile solvent liquid from non-volatile dissolved solid solutes based on boiling point differences.

Key Concept

Sequential physical separation of complex mixtures exploiting magnetism, centrifugal sedimentation of colloids, and differential boiling points.
Estimated Time:2m 0s
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Topics

Sublimation, Magnetization, and Centrifugation