Journal of Hazardous Materials Decontamination of hazardous ...

J. Sunarso, S. Ismadji / Journal of Hazardous Materials 161 (2009) 1–20 9of several pesticides from soil. Later, they concluded that theextractability of pesticides residues from soil was also dependenton the particular pesticide examined and on the nature of residues.Other reports dealing with pesticides removal from soils usingSFE were performed by Koinecke et al. [121] and Sahle-Demessieand Richardson [122]. Koinecke et al. conducted their experimentsin the temperatures range of 60–70 ◦ C and at a pressure of380 bar. Fenpropimorph, pirimicarb, parathion-ethyl, triallate andfenvalerate are utilized as pesticide residues. The best removalefficiency can be attained at 60 ◦ C with 5% methanol as modifier.These authors also tried the supercritical extraction of high contaminatesoil on a bench-scale supercritical extraction unit. Theyassessed the performance of supercritical extraction using pureand modified carbon dioxide as the solvent. They claimed that thebest operating condition was achieved at 30 min extraction time,80 ◦ C, and at pressure of 300 bar with the removal efficiency morethan 98%.A tendency toward more time-effective and environmentfriendlyprocesses has boosted the interest in SFE. Few approacheshave dealt with multi residue analysis of pesticides in soils, whichpresent an additional complexity due to the disparity of chemicalstructures, solubilities in the extraction fluid and interaction withthe matrix. A number of experiments using SFE for analysis ofherbicides and pesticides in soils samples are available in theliteratures [123–126]. In general, the use of supercritical fluidtechnology for the analysis of hazardous materials within soilscreates many advantages such as rapidity, simplicity, great analyteselectivity, good extraction efficiency, clean-up step elimination,suitability for thermally labile compounds, automation, solventlessor near solvent free character and reduced environmental hazard.Polycyclic aromatic nitrogen heterocycles (PANHs), the N-heterocyclic analogue of PAHs belong to the class of thebiologically active environmental pollutants with both mutagenicand carcinogenic properties. Extraction recovery of 10 selectedpolycyclic aromatic nitrogen heterocycles (PANHs), quinoline, 2-methylquinoline, 6-methylquinoline, 8-methylquinoline, acridine,benzo[h]quinoline, phenantridine, indole, 2-methylindole, and carbazolefrom spiked (injected with pollutant compounds) soilsamples was carried out by Koci et al. [127]. They contrasted theperformance of four dissimilar extraction methods (pressurizedsolvent extraction, SFE, soxhlet warm extraction, and standardsoxhlet extraction) to recover these hazardous compounds fromspiked soil samples. As expected, the SFE showed the higher recoveryresult.Contamination of soil by petroleum hydrocarbons poses a majorenvironmental problem. The sources of petroleum hydrocarboncontaminant in soil include crude oil leaks from pipelines, spillsaround production areas, disposal of refinery wastes, and transportfuels leaking from underground storage tanks, etc. The recovery ofpetroleum hydrocarbon from soil remains a challenge due to thedifficulties encountered during the process, since the binding ofpetroleum hydrocarbons with a soil might occur through a numberof mechanisms which are influenced largely by the texturalproperty of the soil as well as its organic and moisture content.Conventional methods to detach this pollutant from soils are timeconsuming and end up in another solvent waste problem, so supercriticalfluid has been shown to be preferred alternative method forthe removal this contaminant from soils [128,129].Composting of garden wastes as an alternative to land-fillingis not economically feasible unless the cost of processing compostcan be offseted by revenues gained from selling the resultant composts.Garden waste, including grass clippings from lawns treatedwith pesticides, generally contains pesticide residues. Bakiomahet al. [130] adopted a new method for simultaneous supercriticalcarbon dioxide extraction of chlorpyrifos and its primary degradate,3,5,6-trichloro-2-pyridinol (TCP), from garden compost. Theysuggested that in situ derivatization with N,O-bis(trimethylsilyl)trifluoracetamide was required for extraction of TCP.It must be mentioned here that in many studies as reportedabove, variation exist in terms of the samples. Samples can be eithera spiked (injected) or real-world sample. The latter sample commonlyhas been subjected to numerous processes such as aging,weathering, chemisorption, etc. that cause them to bind the pollutantstighter.5. Herbicides and pesticides extraction from plant matricesThe requirement to analyze and ascertain foreign substances infruits and vegetables in which their presence being due to chemicaland technological treatments or processes or through environmentalpollution has become a substantial issue nowadays. Thedetermination of pesticide and herbicide residues content on fruitand vegetable products has thus become a more and more strictrequirement for consumers, producers and the authorities that areresponsible for quality controls. In general, the presence of organiccontaminants in fruit and vegetable samples cannot be analyzedwithout some preliminary preparation due to the complexity ofsolid matrices and very low concentration of organic contaminants.As a consequence, the need has arisen to set up increasingly fastand simple analysis methods which can provide the largest possiblerange of results. The drawbacks associated with classical extractiontechniques such as the need for large amounts of solvents, timeconsumingand considerable waste products treatment, have beenovercome by the commencement of matrix solid-phase dispersionin combination with SFE. To date, SFE has also been regarded asan efficient and rapid method for the isolation of hazardous compoundsfrom various kinds of plant matrices. Studies on the removalor analysis of hazardous compounds (pesticides and herbicides)from various kinds of plants matrices have been conducted by manyauthors [131–144] and a brief description of their studies is outlinedin Table 4.Following the exposure of supercritical fluids to fruits or vegetablessamples, the extract mixtures containing the hazardoussubstances can be directly analyzed using GC without the necessityfor any further purification process. Moreover, this technique givessurpassing efficiency than those conventional ones. Satisfactoryextraction efficiencies were reported for non-polar to low polarpesticides such as organochlorine [131,133,135,137,139,141–144]and organophosphorus [131,136,137,141,143]. For pesticidesof high polarity including its metabolites, the addition ofpolar modifiers such as methanol [132,136,138,139], acetone[133,134,136,138], hexane [133,138], ethanol absolute [133], water[132] or water + ethanol mixture [133] to CO 2 enhances its dissolvingpower. Nevertheless, the type of polar modifiers addedrequires careful consideration, since the matrix-swelling effectalso plays a vital role in extraction efficiency [133].Earlier, it has been suggested that vegetation can act as an indicatorof atmospheric contamination, a sink of pollutants as wellas a tool to study the uptake mechanism of atmospheric organic.The mechanism of vegetation uptake of organic pollutants is governedby the chemical and physical properties of the pollutant,environmental conditions, and the plant species [145]. Amongmiscellaneous atmospheric organic pollutants, PAHs are the mostintensively studied compounds. The extraction of PAHs from plantmatrices using SFE was executed by Lang et al. [146]. Fresh andfallen pine needles are picked as the plant matrices. SFE usingtoluene-modified CO 2 is stated as an effective, more selective andfaster extraction technique for contaminant analysis from vegetationmatrices in this study.