ANS:C - Higbie

The Higbie penetration theory, formulated by George E. Higbie in 1935, is a fundamental model used to describe mass transfer in fluid systems, particularly in situations involving the diffusion of solute species across a stagnant or slowly moving fluid boundary layer adjacent to a solid surface. In the Higbie penetration theory, it is assumed that the concentration gradient at the surface of the solid is the driving force for mass transfer, and diffusion is the dominant mechanism governing the transport of the solute through the boundary layer. The theory provides a mathematical framework for calculating the rate of mass transfer across the boundary layer based on the concentration difference between the bulk fluid and the surface of the solid. The key assumptions of the Higbie penetration theory include:

1. Steady-state conditions: The concentration profile in the boundary layer does not change with time.
2. One-dimensional diffusion: Mass transfer occurs predominantly in the direction normal to the solid surface.
3. Negligible convective transport: The fluid flow in the boundary layer is assumed to be negligible compared to diffusion.
4. Constant diffusivity: The diffusivity of the solute in the fluid is assumed to be constant.

The Higbie penetration theory is commonly used to analyze mass transfer processes in various engineering applications, including chemical engineering, environmental engineering, and biotechnology. It provides insights into the design and optimization of processes involving mass transfer across fluid-solid interfaces, such as absorption, adsorption, and catalytic reactions. Overall, the Higbie penetration theory serves as a fundamental tool for understanding and quantifying mass transfer phenomena in fluid systems, particularly in cases where diffusion is the primary mechanism governing mass transport.