Phosphorus adsorption on natural sediments with different pH incorporating surface morphology characterization

Area of Science:

• Environmental Chemistry
• Geochemistry
• Soil Science

Background:

• Sediment composition significantly influences pollutant adsorption in aquatic systems.
• Understanding phosphorus (P) adsorption is crucial for managing water quality and eutrophication.
• pH is a key environmental factor affecting the interaction between sediments and dissolved pollutants.

Purpose of the Study:

• To investigate phosphorus adsorption on sediments from University Lake and Anacostia River across varying pH levels.
• To characterize sediment micro-morphology and pore structure and their impact on P adsorption.
• To develop and apply a model simulating P adsorption incorporating surface morphology and pH effects.

Main Methods:

• Sediment sampling from University Lake and Anacostia River.
• Scanning electron microscopy (SEM) for surface micro-morphology.
• Gas adsorption for pore structure analysis.
• Fourier analysis and Langmuir isotherm for P adsorption modeling.
• Empirical pH function integration.

Main Results:

• Anacostia River sediment exhibited stronger P adsorption compared to University Lake sediment.
• Sediment properties like clay mineral content, median diameter, and pore size distribution influenced P adsorption.
• Increasing pH led to a decrease in both the adsorption equilibrium constant and P adsorption capacity.
• The developed adsorption isotherms accurately reproduced the observed P adsorption behavior with varying pH.

Conclusions:

• Sediment characteristics critically determine phosphorus adsorption capacity and behavior in aquatic environments.
• The integrated modeling approach effectively simulates P adsorption, accounting for surface properties and pH.
• Findings provide valuable insights into pollutant-sediment interactions and transport in aqueous systems.