Mass Transfer

Separating mixtures — the heart of chemical processing. Most of a chemical plant's cost is in separations. Learn molecular diffusion and mass-transfer coefficients, then the major separation operations: distillation, absorption, liquid–liquid extraction, adsorption, drying and humidification — with stage and sizing calculations.

• Diffusion — Diffusion is the movement of molecules from high to low concentration. Learn Fick's law, diffusivities in gases, liquids and solids, steady diffusion through films, mass-transfer coefficients and dimensionless numbers (Sc, Sh), and how diffusion limits separation and reaction rates.
• Distillation — Distillation separates liquids by volatility and is the most common separation in industry. Learn stages, reflux and boil-up, McCabe–Thiele analysis, minimum stages (Fenske), minimum reflux (Underwood), Gilliland correlation, condenser and reboiler duties, and energy-saving configurations.
• Absorption — Gas absorption removes components from a gas by dissolving them into a liquid. Learn Henry's law, minimum liquid rate, absorption factor, Kremser equation for stages, packed columns (HTU/NTU), stripping, and chemical absorption such as amine CO₂ capture.
• Extraction — Liquid–liquid extraction transfers a solute from one liquid to an immiscible solvent. Learn distribution coefficients, extraction factor, single-stage, cross-current and counter-current extraction, solvent selection, ternary diagrams and equipment (mixer–settlers, columns, centrifugal extractors).
• Adsorption — Adsorption captures molecules on the surface of porous solids. Learn adsorbents (activated carbon, zeolites, silica gel, MOFs), isotherms (Langmuir, Freundlich), fixed-bed operation and breakthrough curves, mass-transfer zones, bed sizing, and regeneration (TSA, PSA).
• Drying — Drying removes moisture from solids by evaporation. Learn moisture content (wet and dry basis), equilibrium and critical moisture, constant-rate and falling-rate periods, drying-time calculations, heat requirements, and dryer types (tray, rotary, spray, fluid-bed, freeze).
• Humidification — Humidification operations transfer water between air and water. Learn humidity, relative humidity, dew point, wet-bulb temperature, psychrometric charts, humid heat and enthalpy, cooling towers (range, approach, evaporation, make-up, blowdown) and air conditioning processes.