Background

Prediction of polycyclic aromatic hydrocarbons (PAHs) desorption from soil to estimate available fraction regarding to initial concentration of the contaminant is of great important in soil pollution management, which has poorly been understood until now. In the present study estimation of fast desorption fraction which is considered as available fraction was conducted by evaluating desorption kinetics of phenanthrene (a three ring PAH) from artificially contaminated soils through the mathematical models.

Methods

Desorption rate of phenanthrene (PHE) was investigated by using the nonionic surfactant Tween80 in a series of batch experiments. The effects of reaction time from 5 to 1440 min and initial PHE concentration in the range of 100–1600 mg/kg were studied.

Results

Available fractions of the contaminant were achieved within the first hour of desorption process as the system reached to equilibrium conditions. Experimental data were examined by using kinetic models including pseudo-first-order, pseudo-second-order in four linearized forms, and fractional power. Among the models tested, experimental data were well described by pseudo-second-order model type (III) and (IV) and fractional power equation. Fast desorption rates, as Available fractions were determined 79%, 46%, 40%, 39%, and 35% for initial PHE concentrations of 100, 400, 800, 1200, and 1600 mg/kg respectively. Among the evaluated isotherm models, including Freundlich, Langmuir in four linearized forms, and Temkin, the equilibrium data were well fitted by the first one.

Conclusion

Applying the nonionic surfactant Tween80 is a useful method to determine available fraction of the contaminant. This method will provide the management of contaminated sites by choosing a proper technique for remediation and predicting achievable treatment efficiency.

中文翻译：

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污染土壤中菲的解吸动力学和等温线。

背景

预测土壤中的多环芳烃 (PAHs) 解吸以估计关于污染物初始浓度的可用分数在土壤污染管理中非常重要，但迄今为止人们对此知之甚少。在本研究中，通过数学模型评估人工污染土壤中菲（一种三环多环芳烃）的解吸动力学，对被认为是可用部分的快速解吸部分进行了估计。

方法

通过使用非离子表面活性剂 Tween80 在一系列批次实验中研究了菲 (PHE) 的解吸速率。研究了 5 到 1440 分钟的反应时间和 100-1600 mg/kg 范围内的初始 PHE 浓度的影响。

结果

当系统达到平衡条件时，在解吸过程的第一个小时内就获得了可用的污染物分数。通过使用动力学模型检查实验数据，包括四种线性形式的伪一级、伪二级和分数功率。在测试的模型中，实验数据通过伪二阶模型类型（III）和（IV）和分数幂方程得到了很好的描述。在初始 PHE 浓度为 100、400、800、1200 和 1600 mg/kg 时，快速解吸速率确定为 79%、46%、40%、39% 和 35%。在评估的等温线模型中，包括四种线性形式的 Freundlich、Langmuir 和 Temkin，平衡数据与第一个模型非常吻合。

结论

应用非离子表面活性剂 Tween80 是一种确定污染物可用分数的有用方法。该方法将通过选择适当的修复技术和预测可实现的处理效率来管理受污染的场地。