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Increasing arsenic sorption on red mud by phosphogypsum addition
G Lopes1, L R G Guilherme, E T S Costa
1Department of Soil Science, Federal University of Lavras, Lavras, MG, CEP 37200-000, Brazil.
Journal of Hazardous Materials
|July 17, 2012
Summary
Adding phosphogypsum (G) to red mud (RM) significantly enhances arsenic (As) removal. This mining by-product mixture shows a 3.5-fold increase in As adsorption capacity, offering a sustainable solution.
Area of Science:
- Environmental Science
- Geochemistry
- Materials Science
Background:
- Mining by-products like red mud (RM) are investigated for arsenic (As) remediation.
- Improving the As retention capacity of RM is crucial for reducing environmental bioavailability.
Purpose of the Study:
- To evaluate the efficacy of phosphogypsum (G) in enhancing the As adsorption properties of RM.
- To characterize RM-G mixtures and understand their influence on As retention.
Main Methods:
- Red mud and phosphogypsum were mixed in varying proportions (0-25% G).
- Chemical and mineralogical characterization of the mixtures was performed.
- Arsenic adsorption/desorption experiments were conducted to determine maximum adsorption capacity (AsMAC).
Main Results:
- Arsenic adsorption capacity increased with higher G content in RM.
- Pure RM had an AsMAC of 909 mg kg(-1).
- A mixture of 75% RM and 25% G achieved an AsMAC of 3333 mg kg(-1), a 3.5-fold increase.
Conclusions:
- Incorporating phosphogypsum into red mud significantly boosts arsenic adsorption efficiency.
- The presence of Ca(2+) in G facilitates ternary complex formation, enhancing As retention.
- This method offers a valuable approach for remediating arsenic-contaminated sites using industrial by-products.
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