Related Experiment Video
Updated: Jun 4, 2025
11:14
Two-way Valorization of Blast Furnace Slag: Synthesis of Precipitated Calcium Carbonate and Zeolitic Heavy Metal Adsorbent
Published on: February 21, 2017
12.3K
Competitive Langmuir Model for Dye Mixture Adsorption: Disagreement between Theoretical Ground and Application
Md Akhtarul Islam1, Judama Tawfiq Choudhury1, Fariha Hossain1
1Center for Environmental Process Engineering, Department of Chemical Engineering and Polymer Science, Shahjalal University of Science and Technology, Sylhet 3114, Bangladesh.
Langmuir : the ACS Journal of Surfaces and Colloids
|January 2, 2025
Summary
The competitive Langmuir model fails for multicomponent dye adsorption due to varied interactions. Modifying the model with multiple adsorption constants (K_L) improves predictions for wastewater treatment.
Area of Science:
- Environmental Science
- Adsorption Science
- Chemical Engineering
Background:
- Accurate prediction of multicomponent adsorption is crucial for designing effective industrial wastewater treatment processes for dye removal.
- The standard Langmuir model (LM) accurately describes single-dye adsorption, but the competitive Langmuir model (CLM) often fails in multicomponent systems.
- Understanding the limitations of existing models is key to improving adsorption process design.
Purpose of the Study:
- To investigate the reasons for the failure of the competitive Langmuir model (CLM) in multicomponent dye adsorption systems.
- To define a criterion for the universality of active sites on adsorbents.
- To propose modifications to the CLM for more precise prediction of competitive adsorption.
Main Methods:
- Revisiting the theoretical derivations of the Langmuir model (LM) and competitive Langmuir model (CLM).
- Defining and applying a criterion for the universality of active sites.
- Conducting adsorption and BET tests using three dyes (safranin, crystal violet, methylene blue) and two adsorbents (activated carbon and coconut fiber).
Main Results:
- Activated carbon (AC) met the universality criterion, while coconut fiber (CF) did not.
- Discrepancies in active site density were observed between dye adsorption and BET tests for both AC and CF.
- CLM provided satisfactory predictions for equilibrium adsorption density in binary systems but showed significant gaps in equilibrium concentration.
- The study identified that single K_L values in LM/CLM do not capture the diverse interactions in liquid-phase adsorption.
Conclusions:
- Adsorption in liquid systems involves multiple interaction types, necessitating multiple K_L values in models.
- Classifying active sites as universal or specific based on multiple K_L values enhances CLM accuracy for competitive adsorption.
- Improved CLM predictions will lead to more precise design of dye-contaminated wastewater treatment processes.
