Abstract:

In this study, the capabilities of typical non-ionic surfactant Tween 80 and activated sodium persulfate for the oxidation of polycyclic aromatic hydrocarbons (PAHs) in soil were investigated. The mean PAHs desorption efficiency of 37.8% was obtained when 10% (20 g·L^-1) Tween 80 was used and it increased to 89.5% after 4 times of soil washing. When citrate complexed ferrous sulfate was chosen as an activator and the Fe(Ⅱ) concentration increased from 0.84 mmol·L^-1 to 4.2 mmol·L^-1 coupled with 84 mmol·L^-1 SPS, the PAHs degradation efficiency increased from 64.3% to 73.5%. However, the PAH removal efficiency would then be suppressed if the Fe(Ⅱ) concentration was continuously elevated. When SPS to Fe(Ⅱ) molar ratio was fixed as 20:1, the increase of the SPS concentration up to 168 mmol·L^-1 caused as high as 86.1% of the total PAHs removal rate, which would not be further enhanced with increasing SPS concentration. The presence of 0.25% Tween 80 would increase the PAHs removal rate by 14%. The optimization results showed that the PAHs removal rates of as high as 90.0% could be achieved when the concentrations of Tween 80, SPS, and Fe(Ⅱ) were 0.25%, 42 mmol·L^-1 and 2.1 mmol·L^-1, respectively. Thus, the activated SPS can be applied to effectively oxidized and removed soil PAHs and the efficiency can be improved with the addition of Tween 80. The Tween 80 coupled SPS oxidation will be an effective technique for PAHs removal from soil.

Key words: polycyclic aromatic hydrocarbons, activation, adsorption, surfactants, oxidation

摘要：

考察了在典型非离子表面活性剂Tween 80辅助增溶作用下，活化过硫酸钠（SPS）对多环芳烃（PAHs）污染土壤的氧化修复性能。研究结果表明，室温下10%（20 g·L^-1）的Tween 80对PAHs的平均洗脱效率达到37.8%，连续淋洗样品4次，PAHs平均解吸率可达89.5%以上。当使用柠檬酸（CA）络合硫酸亚铁为活化剂时，在84 mmol·L^-1 SPS浓度条件下，将反应Fe （Ⅱ）浓度由0.84 mmol·L^-1增加至4.2 mmol·L^-1，PAHs的平均去除率可从64.3%提高至73.5%。但当Fe （Ⅱ）浓度继续增大时，PAHs的去除率反而降低。固定SPS与Fe （Ⅱ）摩尔比为20：1，当SPS浓度持续增加至168 mmol·L^-1时，总PAHs的平均去除率可提高到86.1%，之后SPS浓度对PAHs的去除率无显著影响。在活化SPS体系中添加0.25%的Tween 80后，与不加Tween 80的反应系统相比，PAHs平均去除率提高约14%。最终优化结果显示，在0.25% Tween80，42 mmol·L^-1 SPS，2.1 mmol·L^-1 Fe （Ⅱ）浓度条件下，受污染土壤中PAHs平均去除率可达到90.0%。因此，Tween 80强化过硫酸钠可作为PAHs污染场地氧化修复的有效手段。

关键词: 多环芳烃, 活化, 吸附, 表面活性剂, 氧化修复