Lec 52: Adsorption Isotherms and Fixed-Bed Adsorption

Lec 52: Adsorption Isotherms and Fixed-Bed Adsorption

by Prof. Selvaraju Narayanasamy · View the channel on PSI

Applied Sciences & Engineering Agriculture & Food TDCIndustrial chemistry and chemical engineeringTDCXProcess engineering technology and techniques
🎙 Prof. Selvaraju Narayanasamy 👥 230K 📅 September 23, 2026 ⏱ 32 min 👁 5 📄 tutorial 🧭 2026-09-23
Available in: English (current) Français

Keywords

adsorption equilibriumLangmuir isothermFreundlich isothermbreakthrough curvemass balance

Summary

This lecture from NPTEL focuses on adsorption isotherms and the design of fixed-bed adsorption columns. The instructor begins by explaining adsorption equilibrium, where the rates of adsorption and desorption are equal, and introduces the concept of isotherms at constant temperature. Two common isotherm models are discussed: the Langmuir isotherm for monolayer adsorption on homogeneous surfaces, and the Freundlich isotherm for multilayer adsorption on heterogeneous surfaces. Key assumptions, limitations, and practical applications of each model are highlighted. The lecture then shifts to fixed-bed adsorbers, explaining the breakthrough curve, design variables, and the importance of determining bed size and operating time. A detailed mass balance equation is presented, including terms for axial dispersion, convection, liquid-phase accumulation, and solid-phase adsorption. The equation is simplified by neglecting dispersion and assuming dilute solutions. The adsorption steps and resistances (bulk liquid to film, pore diffusion, and surface adsorption) are described. The lecture concludes with practical considerations for column design and process scale-up.

156 words

Critical Evaluation

Value of the Information & Strength of the Argument

The lecture provides a solid foundational understanding of adsorption isotherms and their application in fixed-bed column design. It clearly explains the mathematical models (Langmuir and Freundlich) and their assumptions, which is valuable for engineers designing adsorption systems. The argumentation is logical: it starts with equilibrium concepts, then introduces isotherms, and finally applies them to column design. The instructor uses examples like antibiotic removal to make the content relatable. The presentation is methodical, but some derivations are glossed over for brevity, which is acceptable for an introductory lecture.

Scientific Rigor, Source Quality, Title Accuracy

The scientific rigor is high as it is based on well-established chemical engineering principles. The course is part of NPTEL’s formal curriculum, and the instructor is a professor at IIT Guwahati, lending credibility. While no external references are cited in the lecture, the content aligns with standard textbooks on mass transfer and adsorption. The title accurately reflects the content, covering both isotherms and fixed-bed adsorption as promised. The description includes official course and playlist links, which serve as primary sources for further study.

185 words

Title / Content Match

The title perfectly matches the content; the lecture covers adsorption isotherms and fixed-bed adsorption in detail.

Quality & Reliability

8/10

Lecture from NPTEL, a reputable academic platform, presented by a professor, covering established theory with clear explanations.

Key Moments

Markers derived by PSI from the transcript: the creator did not define chapters.

Cited Sources

Concurring Sources

Contribution & Novelties

This lecture adds value by systematically presenting the core isotherm models and their application to fixed-bed adsorption design. It bridges the gap between theoretical isotherms and practical column sizing, which is essential for bioprocess engineers. The explanation of the mass balance equation and simplification assumptions provides a practical starting point for modeling adsorption columns.

Pour aller plus loin :

  • Langmuir adsorption model — Provides deeper insights into the theoretical basis and extensions.
  • Freundlich equation — Covers the empirical isotherm and its applications in heterogeneous adsorption.
  • Breakthrough curve — Explains the concept of breakthrough in adsorption and its importance in column design.
  • Adsorption — General overview of adsorption processes and types.

110 words

Radar Profile

The profile indicates a balanced information delivery: quantity is moderate, quality is high, technical level is intermediate, and reliability is solid. This reflects a well-structured university lecture that is informative and trustworthy without being excessively advanced.

Reliability 8/10