Efficiency of non-ionic surfactants - EDTA for treating TPH and heavy metals from contaminated soil
© Baziar et al.; licensee BioMed Central Ltd. 2013
Received: 18 July 2012
Accepted: 29 September 2013
Published: 20 December 2013
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Introduction of fuel hydrocarbons and inorganic compounds (heavy metals) into the soil, resulting in a change of the soil quality, which is likely to affect use of the soil or endangering public health and ground water. This study aimed to determine a series of parameters to remediation of TPH and heavy metals contaminated soil by non-ionic surfactants- chelating agents washing process. In this experimental study, the effects of soil washing time, agitation speed, concentration of surfactant, chelating agent and pH on the removal efficiency were studied. The results showed that TPH removal by nonionic surfactants (Tween 80, Brij 35) in optimal condition were 70–80% and 60–65%, respectively. Addition of chelating agent (EDTA) significantly increases Cd and Pb removal. The washing of soil by non- ionic surfactants and EDTA was effective in remediation of TPH and heavy metals from contaminated soil, thus it can be recommended for remediation of contaminated soil.
KeywordsSoil Non-ionic surfactants Chelating agent Total petroleum hydrocarbons Heavy metals
Soil pollution by fuel hydrocarbons and inorganic compounds are major types of pollution [1–3]. Total Petroleum Hydrocarbons (TPH) is a big class of fuel hydrocarbons that originally come from crude oil and are found in large levels in diesel fuels. Some of these compounds in exposure with human and animals can cause cancer, disorder central nervous system and also have harmful effects on liver and lungs . The most common sources of TPH in the environment are accidental releases of crude oil and its products, petroleum refining wastes, petroleum refining products and leaching of oil storage tanks [4–7]. The presences of inorganic compounds such as heavy metals especially lead and cadmium in soil can pose a significant threat to human health and ecological systems . Cadmium and lead are commonly encountered hazardous heavy metals and are in the EPA’s list of priority pollutants [9, 10]. Heavy metals are relatively motionless and persistent in soils as a result of precipitation or adsorption reactions. Industrial facilities are sources of introducing heavy metals into the soil. There are many soil treatments technical methods for contaminated soils including bioremediation, soil washing, soil flushing, thermal desorption, thermal destruction and vapor extraction [11, 12]. Soil washing is a simple and effective technology for rapid removal of hydrocarbons and heavy metals adsorbed into soil ; hence it has been successfully practiced for many years . Literature showed that the soil washing by surfactant can be high effective for hydrophobic pollutants and heavy metals . Metals, semi-volatile organics, PAHs, pesticides and PCBs can be treated by soil washing technique [16, 17]. Surfactants are amphiphilic molecules with a hydrophilic head group and a hydrophobic tail group. They can be: anionic, non-ionic, cationic and amphoteric [18, 19]. The major reasons of using non-ionic surfactants (Tween 80 & Brij 35) in this study include; biodegradable properties, cost-effective and low tendency to flocculants clay particles in soil compared to ionic surfactants. These surfactants enhance the solubility of hydrophobic organic compounds by partitioning them into the hydrophobic cores of surfactant micelles [20–22]. Chelating agents like EDTA and NaCl sometimes are entered to soil washing due to high efficiency of metal extraction, high thermodynamic stabilities of the metal complexes formed, good solubility of metal complexes and normally low adsorption of the chelating agents and their metals complexes on soils .
This process can be affected by several factors including agitation speed, washing time, surfactant concentration, and liquid - soil ratio . The main objective of this study was investigation of non-ionic surfactants and chelating agents on removal of TPH (C10 – C28) and heavy metals (Pb and Cd) in contaminated soil.
Materials and methods
Soil preparation and experimental design
The sample soils were taken from around the diesel stations and petroleum products storage tanks of Zanjan city, Iran. The samples were mixed and sieved using a 2 mm mesh screen. The samples contained 75% sand, 16% clay, 9% silt and 5.89% organic carbon. The soil sample was rinsed two times with distilled water and left on the filter paper to drain the excess water for 24 hours at room temperature (20 ± 2 ċ) and then dried in oven at 60 ċ for two hours.
All experiments in this study were carried out using 100 g of soil in 500 mL Erlenmeyer after adding certain amounts of water, surfactants, chelating agent and adjusting the pH, they were placed in a shaker incubator (model JTSL40). TPH experiments were carried out in different operating variables including the different speed of agitation (100, 150, 200 and 250 rpm), contact times (10, 20, 30, 60, 90 and 120 min), concentrations of surfactants (2, 5, 10, 20, 30 and 60 g/kg) and pHs (2.5, 3, 5, 7, 7.5, 8.5 and 9). Then soil washing continued by adding 0.02 mole EDTA and NaCl simultaneously with the best results obtained from previous steps in order to investigate heavy metal removal. According to the findings of this study, EDTA had higher efficiency relative to NaCl in removing heavy metal, thus experiments carried out with EDTA alone in different concentrations of EDTA (0.01, 0.02, 0.5 and 0.1 mole) and pHs (2–8). After finishing the Washing assays, the suspension was filtered, dried and the TPH and Pb and Cd of samples were measured. The percent removal (%R) of pollutants was calculated using the following formula: %R = C0 – C/C0 *100. Where C0 and C were the concentrations of pollutants before and after washing, respectively.
Characteristic of applied surfactants in this research 
Results and discussion
Effect of agitation speed
Effect of contact time
Effect of surfactant concentration
Effect of pH on TPH removal
Effect of pH on TPH removal, at optimum agitation speed and contact time and concentration obtained from previous steps investigated. No TPH removal was observed and the results are not presented. The main reason is presence of different kinds of organic compounds involving aliphatic and aromatic hydrocarbons in petroleum fractions. Each of these compounds has specific chemical behavior at different pHs. Therefore it is impossible to attained specific pH to remove all of these compounds Mouton et al. investigated effects of pH on removal of PAHs in soil washing . They observed that a decrease of the soil pH to 3 causes a considerable decrease of low (less than five aromatic rings) molecular weight PAH removal (45% to 16%). High molecular weight PAH (more than five aromatic rings) removal is maintained (45– 46%) in these conditions.
Cd and Pb removal
Removal efficienies of Cd and Pb by 2 concentrations of Tween 80 and Brij 35 in the presence of EDTA and NaCl
Pb Removal (%)
Cd Removal (%)
C0 = 350 mg/kg
C0 = 36 mg/kg
Effect of pH on cadmium and lead removal
Removal of metals by different concentrations of EDTA
Washing of soil by tween 80 is an effective and quick method and can be used for remediation of petroleum contaminated soil. It can be a good choice for remediation of both heavy metals and diesel contaminated sites. Although this method was tested for remediation of diesel contaminated soil, it also can be proposed for other soils contaminated with petroleum hydrocarbons. EDTA increases the solubility of heavy metals. Operating conditions which obtained in the present research should be tested on actual sites with organic and inorganic contaminants.
This research is financially supported by Zanjan University of medical sciences.
- Khalladia R, Benhabilesa O, Bentahara F, Mostefa N: Surfactant remediation of diesel fuel polluted soil. J Hazard Mater 2009, 164: 1179–1184. 10.1016/j.jhazmat.2008.09.024View ArticleGoogle Scholar
- Solano-Serena F, Marchal R, Vandecasteele JP: Biodegradation of gasoline in the environment: from overall assessment to the case of recalcitrant hydrocarbons. Revue de l'Institut Français du Pétrole 2001, 56: 479–498.View ArticleGoogle Scholar
- Collins C, Laturnus F, Nepovim A: Remediation of BTEX and trichloroethene - current knowledge with special emphasis on phytoremediation. Environ Sci Pollut Res 2002, 9: 86–94. 10.1007/BF02987319View ArticleGoogle Scholar
- ATSDR: Total petroleum hydrocarbons (TPH). US department of health and human services, public health service Agency for Toxic Substances and Disease Registry. 1999. http://www.atsdr.cdc.gov/tfacts123.pdf Google Scholar
- Lizhong Z, Baoliang C, Jing W, Hongxin S: Pollution survey of polycyclic aromatic hydrocarbons in surface water of Hangzhou, china. Chemosphere 2004, 56: 1085–1095. 10.1016/j.chemosphere.2004.05.025View ArticleGoogle Scholar
- Haigh S: Review of the interaction of surfactants with organic contaminants in soil. Sci Total Environ 1996, 185: 161–170. 10.1016/0048-9697(95)05049-3View ArticleGoogle Scholar
- Iturbe R, Flores-Serrano RM, Castro A, Flores C, Torres LG: Subsoil TPH contamination in two oil pipeline pumping stations and one pipeline right-of-way in north Mexico. J Environ Manage 2010, 91: 2396–2402. 10.1016/j.jenvman.2010.07.003View ArticleGoogle Scholar
- Mahvi AH, Mesdaghinia AR, Naghipoor D: Comparison of heavy metals extraction in contaminated soils by various concentrations of EDTA. J Biol Sci 2005,8(8):1081–1085.Google Scholar
- Cameron RE: Guide to site and soil description for hazardous waste site characterization volume 1: metals. Washington, DC: US Environmental Protection Agency; 1992. http://nepis.epa.gov/Exe/ZyPURL.cgi?Dockey=200097F6.txt Google Scholar
- Ramamurthy AS, Vo D, Li XJ, Qu J: Surfactant.enhanced removal of Cu(II) and Zn(II) from a contaminated sandy soil. Water Air Soil Poll 2008, 190: 197–207. 10.1007/s11270-007-9592-9View ArticleGoogle Scholar
- Scullion J: Remediating polluted soils. Naturwissenschaften 2006, 93: 51–65. 10.1007/s00114-005-0079-5View ArticleGoogle Scholar
- Zhou QX, Hua T: Bioremediation: a review of applications and problems to be resolved. Prog Nat Sci 2004, 14: 937–944. 10.1080/10020070412331344601View ArticleGoogle Scholar
- Ahn CK, Park D, Woo SH, Park JM: Removal of cationic heavy metal from aqueous solution by activated carbon impregnated with anionic surfactants. J Hazard Mater 2009, 164: 1130–1136. 10.1016/j.jhazmat.2008.09.036View ArticleGoogle Scholar
- Villa RD, Trovo AG, Pupo Nogueira RF: Soil remediation using a coupled process: soil washing with surfactant followed by photo-Fenton oxidation. J Hazard Mater 2010, 174: 770–775. 10.1016/j.jhazmat.2009.09.118View ArticleGoogle Scholar
- Doong RA, Wu YW, Lei WG: Surfactant enhanced remediation of cadmium contaminated soils. Water Sci Technol 1998, 37: 65–71.View ArticleGoogle Scholar
- Mulligan CN, Yong RN, Gibbs BF: Surfactant-enhanced remediation of contaminated soil: a review. Eng Geol 2001, 60: 371–380. 10.1016/S0013-7952(00)00117-4View ArticleGoogle Scholar
- Mann MJ: Full-scale and pilot-scale soil washing. J Hazard Mater 1999, 66: 119–136. 10.1016/S0304-3894(98)00207-6View ArticleGoogle Scholar
- Mouton J, Mercier G, Blais JF: Amphoteric surfactants for PAH and lead polluted- soil treatment using flotation. Water Air Soil Poll 2009, 197: 381–393. 10.1007/s11270-008-9819-4View ArticleGoogle Scholar
- Laha S, Tansel B, Ussawarujikulchai A: Surfactant–soil interactions during surfactant-amended remediation of contaminated soils by hydrophobic organic compounds. J Environ Manage 2009, 90: 95–100. 10.1016/j.jenvman.2008.08.006View ArticleGoogle Scholar
- Fountain JC, Klimek A, Beikirch MG, Middleton TM: The use of surfactants for in situ extraction of organic pollutants from a contaminated aquifer. J Hazard Mater 1991, 28: 295–311. 10.1016/0304-3894(91)87081-CView ArticleGoogle Scholar
- Liu Z, Laha S, Luthy RG: Surfactant solubilization of polycyclic aromatic hydrocarbon compounds in soil-water suspensions. Water Sci Technol 1991, 23: 475–485.Google Scholar
- Ussawarujikulchai A, Laha S, Tansel B: Synergistic effects of organic contaminants and soil organic matter on the soil–water partitioning and effectiveness of a nonionic surfactant (Triton X-100). Bioremed J 2008,12(2):88–97. 10.1080/10889860802060170View ArticleGoogle Scholar
- Peng S, Wu W, Chen J: Removal of PAHs with surfactant-enhanced soil washing: influencing factors and removal effectiveness. Chemosphere 2011,82(8):11173–11177.View ArticleGoogle Scholar
- Texas Commission on Environmental Quality. Total Petroleum Hydrocarbons TNRCC Method 1005. 2000. http://www.tceq.state.tx.us/assets/public/compliance/compliance_support/qa/1005_final.pdf
- Aldrich: Detergents properties and applications. 2008. http://www.sigmaaldrich.com/img/assets/15402/Detergent-Selection-Table.pdf Google Scholar
- Moutsatsou A, Gregou M, Matsas D, Protonotarios V: Washing as a remediation technology applicable in soils heavily polluted by mining-metallurgical activities. Chemosphere 2006, 63: 1632–1640. 10.1016/j.chemosphere.2005.10.015View ArticleGoogle Scholar
- Zheng Z, Obbard JP: Oxidation of polycyclic aromatic hydrocarbons (PAH) by the white rot fungus, Phanerochaete chrysosporium. Enzyme Microb Technol 2002,31(1):3–9.View ArticleGoogle Scholar
- Djedidi Z, Drogui P, Ben Cheikh R, Mercier G, Blais JF: Laboratory study of successive soil saline leaching and electrochemical lead recovery. J Environ Eng 2005, 131: 305–314. 10.1061/(ASCE)0733-9372(2005)131:2(305)View ArticleGoogle Scholar
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