Evaluation of effective parameters in washing of PAH-contaminated soils using response surface methodology approach

The aim of this study was to investigate the effects of temperature, time, and surfactants on washing of soil contaminated with PAHs. In this regard, samples were collected from a petrochemical company in Bandar-e Emam and the washing process was conducted. SDS and Tween 80 were selected to compare the effects of anionic and non-ionic surfactants. Applying design of experiment approach, 20 tests were to evaluate the effects of each parameter. Results showed that fluoranthene and benzo(a)pyrene presented lowest removal efficiencies. Phenantherene and fluoranthene were more dependent to the parameters. For antheracene, naphtalene, pyrene, and benzo(a)pyrene, there was not any preference in using SDS or Tween 80. However, fluoranthene and chrysene demonstrated a better removal rate using SDS, and removal of fluorene and phenantherene was more efficient using a 1:1 mix of surfactants. In addition, quadratic model developed on removal of PAHs was verified by its high coefficient of correlation (R2 = 0.93). Moreover, experimental result (79.63) was consistent with the model�s predicted value (80.29). According to ANOVA, temperature was the most influential factor. The interaction terms in model were insignificant unless for time and temperature (0.05 < P value < 0.1). As a conclusion, using surfactants with an optimum ratio may enhance the removal rate up to 4.5. Results showed that 60 °C, 33 min of washing and ratio of 0.625 were the optimum conditions, leading to 85.41 removal rate which is in close agreement with actual result (83.6). Three studied parameters were effective on washing process, and their effects were optimized when used in specified values. © 2019, Islamic Azad University (IAU)

Evaluation of effective parameters in washing of PAH-contaminated soils using response surface methodology approach

The aim of this study was to investigate the effects of temperature, time, and surfactants on washing of soil contaminated with PAHs. In this regard, samples were collected from a petrochemical company in Bandar-e Emam and the washing process was conducted. SDS and Tween 80 were selected to compare the effects of anionic and non-ionic surfactants. Applying design of experiment approach, 20 tests were to evaluate the effects of each parameter. Results showed that fluoranthene and benzo(a)pyrene presented lowest removal efficiencies. Phenantherene and fluoranthene were more dependent to the parameters. For antheracene, naphtalene, pyrene, and benzo(a)pyrene, there was not any preference in using SDS or Tween 80. However, fluoranthene and chrysene demonstrated a better removal rate using SDS, and removal of fluorene and phenantherene was more efficient using a 1:1 mix of surfactants. In addition, quadratic model developed on removal of PAHs was verified by its high coefficient of correlation (R 2 = 0.93). Moreover, experimental result (79.63) was consistent with the model�s predicted value (80.29). According to ANOVA, temperature was the most influential factor. The interaction terms in model were insignificant unless for time and temperature (0.05 < P value < 0.1). As a conclusion, using surfactants with an optimum ratio may enhance the removal rate up to 4.5. Results showed that 60 °C, 33 min of washing and ratio of 0.625 were the optimum conditions, leading to 85.41 removal rate which is in close agreement with actual result (83.6). Three studied parameters were effective on washing process, and their effects were optimized when used in specified values. © 2019, Islamic Azad University (IAU)