Treatment of soil eluate containing nitro aromatic compounds by adsorption on activated coke (AC)

Soil washing is a kind of physical method to remove organic matters from contaminated soil. However, its eluent after washing may result in secondary pollution to the environment. In this study, activated coke (AC) was used to remove organic pollutants from contaminated soil eluent. The effect of temperature, initial chemical oxygen demand (COD) and AC dosage on COD removal efficiency was investigated. The results showed that the organic matter can be removed in the eluent for the COD dropped a lot. When the AC dosage was 20 g·L −1 , 88.92% of COD decreased after 480 min of adsorption at 50 °C. The process of adsorption can be described by the Redlich–Peterson isotherm. The adsorption was spontaneous and endothermic. The pseudo-second-order model can be used to describe the adsorption process. After adsorption, the acute toxicity of the eluent was reduced by 76%, and the water qualities were coincident with Chinese discharge standard GB 14470.1-2002, which means it could be emitted to the environment.