THERMODYNAMIC ASPECT OF PAHS UNDER OXIDATIVE AND REDUCTIVE CONDITIONS

Abstract

Polycyclic Aromatic Hydrocarbons (PAHs) are hazardous and ubiquitous organic pollutants having fused aromatic rings. Bioremediation of PAHs is recalcitrant and their spontaneous degradation does not occur because of the thermodynamically unfavorable environmental conditions. Bioremediation of PAHs via microbes depends on oxidative-reductive potential varying with an electron donor and electron acceptor. Oxygen is a natural electron acceptor used to oxidize organic pollutants. In the absence of oxygen, redox potential decreases causing thermodynamically unfavorable conditions while microbial respiration is an energy-producing mechanism in which free energy is released per electron equivalent of substrate. Therefore, the anaerobic metabolic pathway is preferred for the degradation of PAHs instead of the aerobic pathway. Thus, the thermodynamic fate of PAH mineralization either depends on the electron acceptor or electron donor.