Phosphate removal from industrial wastewaters using layered double hydroxides.
Marina Avena Maia1,2, Guilherme L Dotto3, Oscar W Perez-Lopez2
1Laboratory for Leather and Environmental Studies - LACOURO, Department of Chemical Engineering, Federal University of Rio Grande do Sul, Porto Alegre, Brazil.
Environmental Technology
|January 25, 2020
Summary
Mg-Al and Zn-Al layered double hydroxides (LDH) effectively remove phosphate from wastewater. Adsorption followed pseudo-second order kinetics, with Mg-Al showing 74% removal in industrial wastewater, though co-existing anions reduced efficiency.
Area of Science:
- Environmental Chemistry
- Materials Science
- Water Treatment
Background:
- Phosphate pollution is a significant environmental concern, impacting water quality and ecosystems.
- Layered double hydroxides (LDH) are promising materials for adsorptive removal of pollutants.
- Developing efficient adsorbents for phosphate removal from industrial wastewater is crucial.
Purpose of the Study:
- To synthesize and characterize Mg-Al and Zn-Al layered double hydroxides (LDH).
- To evaluate the efficacy of these LDH materials in removing phosphate from synthetic and industrial wastewater.
- To investigate the adsorption kinetics, equilibrium, and the influence of co-existing anions on phosphate removal.
Main Methods:
- Co-precipitation method for synthesizing Mg-Al and Zn-Al LDH.
- Characterization using X-ray diffraction (XRD), BET surface area analysis, thermal analysis (TG-DTA), and FTIR spectroscopy.
- Phosphate adsorption experiments in synthetic solutions and industrial wastewater, analyzing kinetics and equilibrium.
Main Results:
- XRD and TG-DTA confirmed the formation of LDH structures for both Mg-Al and Zn-Al.
- Phosphate adsorption kinetics were best described by the pseudo-second order model.
- Equilibrium data fitted well to Sips and Freundlich models for Mg-Al and Zn-Al LDH, respectively.
- Mg-Al adsorbent achieved 74% phosphate removal at a dosage of 5 g/L in industrial wastewater.
- Phosphate removal efficiency decreased in the presence of co-existing anions.
Conclusions:
- Mg-Al and Zn-Al LDH are effective adsorbents for phosphate removal.
- The adsorption process is dependent on kinetics and equilibrium models, with pseudo-second order kinetics being dominant.
- Industrial wastewater conditions, particularly the presence of other anions, can impact adsorbent performance.
- Mg-Al LDH shows significant potential for practical application in phosphate removal from industrial effluents.
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