Dairy & Food Engineering-I

• Driving Force in Membrane Dialysis:
• Transport Phenomenon:
• Dialysis is a membrane separation process where solutes diffuse across a semipermeable membrane down a concentration gradient (chemical potential gradient).
• Driven purely by concentration differences, without requiring external hydrostatic pressure (unlike Reverse Osmosis) or electric potential (unlike Electrodialysis).
• Conclusion: Concentration (Option 3).

Correct option: (3) Concentration

• Ultrasonic Membrane Cleaning Frequency:
• Acoustic Cavitation Mechanics:
• Power ultrasound de-fouls filtration membranes (UF/RO) by inducing acoustic cavitation—microscopic bubble formation and violent collapse producing localized shock waves and high-velocity microjets that dislodge foulant foul cakes.
• Operates in the low-frequency power ultrasound regime of $20 - 40\text{ kHz}$.
• Conclusion: 20-40 KHz (Option 2).

Correct option: (2) 20-40 KHz

• Driving Force in Membrane Dialysis:
• Transport Mechanics:
• Solutes diffuse through a semipermeable membrane driven solely by a concentration difference (chemical potential gradient).
• Does not utilize hydrostatic pressure or electrical voltage.
• Conclusion: Concentration difference (Option 1).

Correct option: (1) Concentration difference

• Properties and Applications of Polypropylene (PP):
• Polymer Characteristics:
• Low density ($0.90 - 0.91\text{ g/cm}^3$) and high melting temperature ($160 - 165^\circ\text{C}$), allowing retort sterilization and microwave heating.
• Packaging Forms:
• Polypropylene is utilized in both rigid and flexible forms—rigid bottles, injection-molded closures, thin-walled thermoformed tubs, as well as flexible oriented films (BOPP) for snack pouches and bread packaging.
• Therefore, asserting that it is used only in rigid forms is completely incorrect.
• Conclusion: It is used only in rigid forms as in bottles (Option 2).

Correct option: (2) It is used only in rigid forms as in bottles