The Fate of Xylene Spilled into Soil: Effects of Heavy Metals and Rainfall
2022
Chen, Yuan | Zhang, Tong | Luo, Shuai | Zhang, Yurong | Liu, Yuanyuan
Xylene is a typical petrochemical industry pollutant. The fate of xylene spilled into soil was investigated in laboratory-scale batch and column experiments. The results show that free xylene in the soil evaporated quickly (7.2–10.4 mg h⁻¹), but any fraction adsorbed onto the soil particles evaporated much more slowly (2.3–2.4 mg h⁻¹). The retention of xylene in the soil was mainly controlled by its adsorption onto the soil minerals. The adsorption was best described using a pseudo-second-order kinetic model and Langmuir model. Adsorption up to 530 mg kg⁻¹ was observed, and minerals such as quartz and kaolinite were the key adsorbents. Adsorption of xylene was promoted by the presence of dissolved organics up to about 50 mg L⁻¹, but it was significantly inhibited by cobalt-bearing compounds which are often used as catalysts in the petrochemical industry. The release of xylene from soil would be facilitated by intense rainfall and cobalt-bearing compounds but would be inhibited with the increase of rainwater acidity. This study reveals the environmental behavior of xylene in soil and provides scientific guidance for pollution control and risk assessment of BTEX contaminated sites.
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