Influence of Ca(OH)2 on the Extraction Efficiency of Nitroaromatic Compounds from Soils

High concentrations of TNT and related nitroaromatic compounds (NAC) can still be found in the soils. To evaluate the alkaline hydrolysis of NAC as a new remediation technology, two highly contaminated soils were treated under alkaline conditions using Ca(OH)₂ as base. However, instead of the expected decrease, a temporary or even permanent increase was observed for several NAC. The extent of the intensity was affected by Ca(OH)₂ concentration, suggesting the existence of desorption processes in the soil. The extent of the increase also depends on the soil investigated, the highest being observed with 1,3,5-trinitrobenzene (239 mg kg^?1 compared to the baseline concentration of 24 mg kg^?1) in the HTNT2 soil. This indicates incomplete NAC extraction and, hence, too low NAC concentrations measured in soils when conventional extraction procedures are used.