Supercritical fluid extraction of coal tar contaminated soil

Yu, Xiaobing; Wang, Xiaoping; Bartha, Richárd; Rosen, Joseph D.

doi:10.1021/es00081a017

Cited by 52 publications

(18 citation statements)

References 5 publications

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“…The above results are in accordance with previous findings [20,39,41], which suggested that the soil matrix was most important in controlling desorption behavior and the extraction amount of contaminant was a function of its molecular weight, its …”

Section: Optimization Of the Solvothermal Proceduressupporting

confidence: 92%

Advantage of solvothermal procedure for polychlorinated biphenyls removal from e-waste contaminated site

Zhang

Zhu

Zhang

2011

Chemical Engineering Journal

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a b s t r a c tPolychlorinated biphenyls (PCBs) are environmentally persistent, toxic, bioaccumulative and recalcitrant. In this study, aged PCBs from e-waste contaminated site were respectively subjected to Soxhlet and solvothermal treatments. The results indicated that solvothermal method was much more predominant for PCBs removal than traditional Soxhlet method. Sequential Soxhlet-solvothermal experiment demonstrated that Soxhlet unextractable (bound) PCBs were efficiently removed by solvothermal procedure due to enhanced solvating effects of organic solvents. The key point was that bound PCBs in the aged soil were partitioned in different components of soil organic matter, e.g., the solvothermal removal amounts of I-V PCBs (sum of PCB8, PCB18, PCB28, PCB44, PCB66) from fulvic acid (FA), humic acid (HA), bound humic acid (bound HA), bound lipids and mineral fraction were 0.4, 40.8, 28.4, 19.8, and 10.6%, respectively. It was found that isopropanol was the most effective solvent for PCBs removal. The optimum performing temperature, time and liquid to solid ratio for PCB8, PCB18, PCB28, PCB44, and PCB66 were 170 • C, 8 h and 10:1, respectively. As for higher molecular weight PCB congeners, these conditions were 150 • C, 10 h and 15:1. Soil organic matter content was unchanged after solvothermal treatment indicating that soil fertility remained after the removal process. This work provides a more clean process for effective treatment of soils contaminated by persistent organic pollutants (POPs) in comparison to traditional methods.

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Section: Optimization Of the Solvothermal Proceduressupporting

confidence: 92%

Advantage of solvothermal procedure for polychlorinated biphenyls removal from e-waste contaminated site

Zhang

Zhu

Zhang

2011

Chemical Engineering Journal

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“…Soil and dust In uncontaminated soils mean naphthalene levels were determined in the range between <1 and 20 lg/kg (peak values up to 131 lg/kg), whereas much higher levels have been found in the immediate vicinity of contaminated sites, with the highest concentration being 6,410 mg/kg (Aamot et al 1996;Aldis et al 1983;Ashok et al 1995;Ball 1987;Bedient et al 1984;Chen et al 1996;Chuang et al 1999;GonzalezVila et al 1988;Hawthorne et al 2002;Jones et al 1987Jones et al , 1989aJones et al , 1989bKaplan et al 1996;Kipopoulou et al 1999;Kliest et al 1989;Lindhardt et al 1996;Navarro et al 1991;Naylor and Loehr 1982;Ou et al 1992;Parker and Wolfe 1990;Sweetman et al 1992;Turney and Goerlitz 1990;Vogt et al 1987;Webber and Lesage 1989;Wild et al 1990;Yu et al 1990). An average daily intake of naphthalene from soil was calculated by the US EPA (2002) to be 0.235 lg/kg per day and 3.3 lg/kg per day for adults and children, respectively (Table 2).…”

Section: Environmental Exposure To Naphthalenementioning

confidence: 99%

Naphthalene?an environmental and occupational toxicant

Preuss

Angerer

Drexler

2003

International Archives of Occupational and Environmental Health

277

149

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For many years naphthalene had been considered as a non-carcinogenic polycyclic aromatic hydrocarbon (PAH). Airborne naphthalene concentrations have always been observed to be below the limit values of various national committees, such as the threshold limit value (TLV) of the American Conference of Governmental Industrial Hygienists (ACGIH) and the MAK of the Deutsche Forschungsgemeinschaft (DFG) (10 ppm). Since 2000, when the US National Toxicology Program revealed clear evidence of the carcinogenic activity of naphthalene in rats, international agencies [the International Agency for Research on Cancer (IARC), the US Environmental Protection Agency (US EPA), DFG] have reclassified naphthalene as a potential human carcinogen, and the European Union (EU) is currently preparing a new risk assessment report. It is presently unknown how to protect humans from health risks resulting from occupational and environmental naphthalene exposure. Knowledge about the external and internal exposure of humans serves as the key determinant in a comprehensive risk assessment. We review here ambient monitoring studies concerning the external naphthalene exposure that results from ubiquitous environmental sources (indoor and outdoor air, water, soil, food) and from a variety of critical workplaces (coking plants, creosote impregnation, distillation of coal tar and naphthalene, manufacture of refractories, graphite electrodes, aluminium and mothballs). Based on results of ambient monitoring studies published so far, a new hygiene-based exposure limit of 1.5 mg naphthalene per cubic metre of air (0.3 ppm) is proposed. Furthermore, results from biological monitoring studies are summarised in this article. The internal burden was almost exclusively determined by means of the urinary metabolites 1-naphthol and 2-naphthol, but it is currently not possible for one to evaluate a biological tolerance level (BAT) or a biological exposure index (BEI). Based on the toxicokinetics and metabolism of naphthalene, the central question on its carcinogenicity is briefly sketched. Naphthoquinones play an important role in this context. Their adducts with macromolecules may be the parameters of choice for the estimation of effects to human health.

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“…Methanol, in particular, increased the extraction efficiency. Yu et al 1990 [11 50-65 O C 150-350 atm soil and sand 92% of the polycyclic aromatic hydrocarbons were removed from a coal tar contaminated soil with a mixture of 95%CO2/ 5 % methanol.…”

Section: Whc-ep-os92mentioning

confidence: 99%