Estimation of apparent rate coefficients for phenanthrene and pentachlorophenol interacting with sediments

Area of Science:

• Environmental Chemistry
• Environmental Science
• Geochemistry

Background:

• Organic pollutants in water-sediment systems pose environmental risks.
• Understanding pollutant sorption dynamics is crucial for risk assessment.
• Phenanthrene and pentachlorophenol (PCP) are common organic pollutants.

Purpose of the Study:

• To investigate the sorption behavior of phenanthrene and PCP in sediments.
• To model the time-dependent interactions of these pollutants with sediment fractions.
• To elucidate the mass transfer processes between reversible and irreversible sediment phases.

Main Methods:

• Application of a compartment model to describe pollutant-sediment interactions.
• Utilizing first-order differential equations to model phase interactions.
• Employing numerical optimization software to obtain apparent rate constants.
• Experimental extraction using hot methanol to determine pollutant concentrations.

Main Results:

• The reversible sediment phase increased initially then decreased, indicating mass transfer.
• The irreversible sediment phase showed a continuous increase over the sorption period.
• Extraction efficiency of phenanthrene and PCP decreased with increasing sorption time.
• Apparent rate constants for sorption were successfully obtained via model fitting.

Conclusions:

• A compartment model effectively describes phenanthrene and PCP sorption in sediments.
• Mass transport occurs between reversible and irreversible sediment fractions.
• Sorption time influences both the partitioning of pollutants and extraction efficiency.