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Kinetics of dodecanoic acid adsorption from caustic solution by activated carbon
Phillip Pendleton1, Sophie Hua Wu
1Center for Molecular and Materials Sciences, University of South Australia, SA 5095, Mawson Lakes, Australia. p.pendleton@unisa.edu.au
Journal of Colloid and Interface Science
|October 7, 2003
Summary
Adsorbent surface chemistry, particularly oxygen content, significantly impacts dodecanoic acid adsorption kinetics. Surface diffusion, not porosity, primarily controls the adsorption process for activated carbons.
Area of Science:
- Environmental Chemistry
- Materials Science
- Chemical Engineering
Background:
- Activated carbons are widely used adsorbents for various pollutants.
- Understanding adsorption kinetics is crucial for optimizing removal processes.
- Dodecanoic acid adsorption is relevant in wastewater treatment and industrial applications.
Purpose of the Study:
- To investigate the effects of adsorbent properties and operational parameters on dodecanoic acid adsorption kinetics.
- To elucidate the dominant mass transfer mechanisms governing dodecanoic acid adsorption.
- To assess the influence of adsorbent porosity, surface chemistry, and carbon dosage on adsorption rates.
Main Methods:
- Batch adsorption experiments were conducted using steam-activated carbons from coconut and coal precursors.
- Adsorbents were pre-treated with deionized water or 2 M NaOH.
- Adsorption kinetics were analyzed using mass transfer and diffusion coefficients.
- Molecular and Knudsen diffusion models were applied.
Main Results:
- Adsorbent porosity had a minor influence on adsorption kinetics.
- High surface oxygen content on activated carbons impeded dodecanoic acid transport.
- Carbon dosage affected transport coefficients proportionally, but normalized coefficients remained constant.
- Surface diffusion was identified as the rate-limiting step in the adsorption process.
Conclusions:
- Surface chemistry, specifically oxygen functional groups, plays a critical role in dodecanoic acid adsorption kinetics.
- Adsorbent porosity is less influential than surface properties in controlling adsorption rates.
- Surface diffusion is the primary mechanism governing dodecanoic acid adsorption onto activated carbons.