Irreversible adsorption/desorption of neutral organic hydrocarbons to natural sediments

Conference · Sun Dec 31 04:00:00 EST 1995

OSTI ID:442874

Kan, A T; Fu, G; Hunter, M; Chen, W; Tomson, M B ^[1]

---

1. Rice Univ., Houston, TX (United States). Dept. of Environmental Science and Engineering

This paper is to investigate the adsorption/desorption irreversibility of neutral organic hydrocarbons to well-characterized uncontaminated sediments and historically contaminated sediments. Naphthalene, phenanthrene and 2,2{prime},5,5{prime} tetrachlorobiphenyl are the neutral organic hydrocarbons studied in the laboratory system. The historically contaminated sediments were obtained form the Lake Charles, LA and contained predominantly the chlorinated benzenes, phthalates, and a small amount of PAHs. In multiple batch adsorption/desorption experiments, the maximum concentration of hydrocarbons that resist desorption has been measured to be around 0.1 to 10 {micro}g/g for the sediments investigated in this study. The maximum concentration observed in this study is not in contradiction to the concentration that resist desorption in many literature reported field observations. When this maximum concentration is satisfied, the adsorption/desorption of hydrocarbons appears to be linear and reversible. The fraction of the adsorbed mass that becomes irreversibly sorbed varied with the initial hydrocarbon concentration that is available for adsorption. The observed irreversible desorption is at thermodynamic equilibrium with the liquid phase and the equilibrium concentration is about two to three orders of magnitude lower than prediction. The magnitude of the increased heat of reaction is about 10 kJ/mol and the magnitude of increase stability energy is about {minus}16 kJ/mol for the irreversible compartment. The observed data is unique that none of the existing theoretical model can be used to explain the data. Therefore, a new mechanism that causes irreversible adsorption/desorption is proposed and will be discussed.

• OSTI ID: 442874
• Report Number(s): CONF-961149--
• Country of Publication: United States
• Language: English

Related Subjects

54 ENVIRONMENTAL SCIENCES
CHLORINATED AROMATIC HYDROCARBONS
NAPHTHALENE
PHENANTHRENE
POLYCYCLIC AROMATIC HYDROCARBONS
SEDIMENTS
WATER CHEMISTRY
WATER POLLUTION