Filtration of volatile liquids: which filtration method is generally unsuitable due to loss of solvent and safety concerns when handling highly volatile liquids?

Introduction / Context:
Volatile liquids (low boiling point, high vapor pressure) pose special challenges during filtration: solvent losses, vapor handling, potential freezing by evaporative cooling, and flammability hazards. Selecting the appropriate driving force (pressure, gravity, vacuum, or centrifugal field) directly affects process safety and product recovery.

Given Data / Assumptions:

• Liquid is volatile and easily evaporates under reduced pressure.
• Objective: separate suspended solids with minimal solvent loss.
• Equipment choices include vacuum, pressure, gravity, and centrifugal filters.

Concept / Approach:
Vacuum filtration operates below atmospheric pressure on the filtrate side, promoting evaporation of volatile solvents. Evaporation increases emissions, can chill the cake, change viscosity, and create flammability/explosion risks. By contrast, pressure filtration encloses and often pressurizes the system, limiting vaporization. Gravity and centrifugal filters can also be designed to minimize vapor loss compared to vacuum systems.

Step-by-Step Solution:
Identify hazard: reduced pressure accelerates solvent vaporization.Link to equipment: vacuum filters inherently lower pressure at the filtrate side.Conclude unsuitability: vacuum filters are generally unsuitable for volatile liquids.

Verification / Alternative check:
Process safety guidelines recommend closed pressure nutsche or pressure-leaf filters for volatile/flammable solvents to reduce losses and contain vapors.

Why Other Options Are Wrong:
Pressure filter: enclosed, allows vapor containment and nitrogen blanketing.Gravity filter: can work with covers; not ideal for rates but safer than vacuum as to vaporization.Centrifugal filter: enclosed basket/peeler designs can mitigate vapor loss.

Common Pitfalls:
Assuming faster dewatering is always better; for volatile solvents, containment and safety outweigh marginal cycle-time gains from vacuum operation.

Final Answer:
Vacuum filter