Competition in chromate adsorption onto micro-sized granular ferric hydroxide
Inga Hilbrandt1, Aki Sebastian Ruhl1, Frederik Zietzschmann1
1Technische Universität Berlin, Chair of Water Quality Control, Str. des 17 Juni 135, 10623 Berlin, Germany.
Chemosphere
|December 4, 2018
Summary
Micro-sized iron hydroxide effectively removes toxic hexavalent chromium from drinking water. Adsorption is pH-dependent and influenced by competing ions like bicarbonate, with reversible mechanisms observed.
Area of Science:
- Environmental Science
- Water Treatment Technology
- Materials Science
Background:
- Hexavalent chromium (Cr(VI)) poses significant toxicity risks in drinking water.
- Effective removal technologies are crucial for ensuring water safety.
- Micro-sized iron hydroxide (μGFH) is explored as a potential adsorbent.
Purpose of the Study:
- To evaluate the adsorption capacity of μGFH for chromate removal from drinking water.
- To investigate the influence of pH and competing ions on adsorption efficiency.
- To understand the adsorption mechanisms and kinetics.
Main Methods:
- Adsorption experiments using μGFH in deionized and drinking water.
- Application of Freundlich and Langmuir models to describe adsorption behavior.
- Investigation of desorption, competing ion effects, and kinetic studies.
- Modeling using homogeneous surface diffusion model (HSDM).
Main Results:
- Adsorption capacity significantly decreased in drinking water (1.9 mg/g Cr(VI)) compared to deionized water (5.8 mg/g Cr(VI)) at pH 7.
- Adsorption increased with decreasing pH.
- Bicarbonate was identified as the primary inhibitor, while calcium enhanced adsorption.
- Adsorption kinetics depended on particle size and adsorbent dose, with equilibrium reached faster for smaller particles.
- Reversible adsorption indicated ion exchange and outer sphere complex mechanisms.
Conclusions:
- μGFH shows potential for chromate removal, but its efficiency is reduced by drinking water matrix components, especially bicarbonate.
- Understanding competitive ion effects and pH dependency is vital for optimizing water treatment processes.
- The study provides insights into adsorption mechanisms and kinetics for effective Cr(VI) removal.
Keywords:
Adsorption kineticsChromate adsorptionCompetitive adsorption modellingGranular ferric hydroxideMore Related Videos
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