Binding of 4-monochlorophenol to soil

Halogenated phenolic compounds such as chlorophenols are capable of binding to organic matter during the humification processes in soil. The incorporation of phenols into organic macromolecules, i.e., covalent bond formation, results from biologically or chemically catalyzed reactions. Standard batch sorption experiments performed in our laboratory showed a significant enhancement in soil associated 4-monochlorophenol (4-MCP) in the presence of oxygen possibly as a result of covalent binding. Sorbed 4-MCP was subjected to desorption by consecutive water and solvent extractions. Nearly 15% of the soil-associated 4-MCP remained unextracted. The unextracted [U-ring-C-14]-4-MCP consisted of a fraction incorporated into humic and fulvic acids and a second fraction associated with humin or soil mineral surface and recovered as (CO2)-C-14 during soil combustion. Autoclaving the soil before 4-MCP addition resulted in a reduction in the amount of the nonextractable C-14. The addition of H2O2 caused a 4.4-fold increase in 4-MCP binding. Hydrogen peroxide, which appears to enhance both biological and abiotic coupling processes, can be added to soil as a stimulant of oxidative coupling activity.