Tween 80 enhanced-activated sodium persulfate oxidation of PAHs contaminated soil

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. © All Right Reserved.