Tratabilidade de solo contaminado com naftaleno através de oxidação química: análises da fase sorvida, aquosa e vapor

Abstract

Soil contamination by polycyclic aromatic hydrocarbons (PAHs) is a worldwide discussed subject. Naphthalene (NAP) is a PAH and it is among the 16 priority pollutants listed by the United States Environmental Protection Agency (USEPA). Advanced oxidation processes can be applied for remediation of PAH contaminated areas through the use of chemicals such as persulfate. This oxidant can be activated by either alkaline medium or ferrous iron, among other forms. The aim of this work was the evaluation of treatability experiments using chemical oxidation in a sandy soil artificially contaminated with naphthalene. Solid-liquid and liquid-liquid extractions were performed for sorbed and aqueous phases, respectively, according to USEPA methods. The collected samples were analyzed by gas chromatography coupled with mass spectrometry (GC-MS). The vapor phase was also collected and analyzed in the GC-MS. According to the factorial design applied, 2³ + 3 central points, the reaction optimum conditions were: [PS] = 18.37 g L-1 ; [FeSO4] = 4.25 g L-1 ; and pHinitial = 3.00. 82.61±1.19% of NAP removal was achieved. More than 60% of the NAP in the system was transferred to the vapor phase at the beginning of the process. At the end of the reaction, more than 99% of NAP in the vapor phase was removed. Regarding to the NAP concentration in the soil, it was possible to reach levels below the intervention value stipulated by the Environmental Company of São Paulo (CETESB). First order reaction fit accurately the kinetic series of experimental data, indicating that degradation time is directly proportional to the NAP concentration in the system.