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Soil and Sediment Contamination: An InternationalJournalISSN: 1532-0383 (Print) 1549-7887 (Online) Journal homepage: http://www.tandfonline.com/loi/bssc20A Biosurfactant/Polystyrene Polymer PartitionSystem for Remediating Coal Tar-ContaminatedSedimentNicholas M. Wilton, Christian D. Zeigler, Riccardo Leardi & Albert Robbat Jr.To cite this article: Nicholas M. Wilton, Christian D. Zeigler, Riccardo Leardi & Albert RobbatJr. (2016): A Biosurfactant/Polystyrene Polymer Partition System for Remediating Coal TarContaminated Sediment, Soil and Sediment Contamination: An International Journal, DOI:10.1080/15320383.2016.1190955To link to this article: epted author version posted online: 01Jun 2016.Published online: 01 Jun 2016.Submit your article to this journalArticle views: 55View related articlesView Crossmark dataFull Terms & Conditions of access and use can be found tion?journalCode bssc20Download by: [Tufts University]Date: 20 July 2016, At: 13:47

SOIL AND SEDIMENT CONTAMINATION2016, VOL. 0, NO. 0, 955A Biosurfactant/Polystyrene Polymer Partition System forRemediating Coal Tar-Contaminated SedimentNicholas M. Wiltona, Christian D. Zeiglera, Riccardo Leardib, and Albert Robbat, Jr.aDownloaded by [Tufts University] at 13:47 20 July 2016aDepartment of Chemistry, Tufts University, Medford, MA, USA; bDepartment of Pharmacy, University of Genoa,Genoa, ItalyABSTRACTKEYWORDSA sustainable, green chemistry process is proposed for the cleanup ofcoal tar impacted sediment in under 2 hr. A mixture of proteins andpolypeptides, extracted from corn gluten meal and hemp, when mixedwith sediment and polystyrene foam pellets (PFPs), serves to mobilizetar, which sorbs onto PFP. Since the sorbent floats, coal tar is easilyextracted from the agitation vessel. An empirically derived 4dimensional surface response model accurately predicts removal ratesof the tar and operational costs of the system under variousexperimental conditions. At optimum relative to cost, 81% of the twoto six ring polycyclic aromatic hydrocarbons (PAHs) and 73% of thetotal tar mass are removed despite high sediment organic carboncontent (16.4%) and silty fines (»85%). Multiple PFP extractions (n D 2)of the same sediment/biosurfactant mixture yielded 94% extraction ofPAH. Scanning electron microscope images illustrate free-phase tar(globule) sorption onto the foam. A field pilot was conducted in which25 kg of sediment was processed. Results were in excellent agreementwith both lab (10 g) experiments and model predictions. The process isconsidered sustainable and green because the active ingredients arederived from renewable crop materials, recycled polystyrene is used,and the biosurfactant is recyclable which reduces water demand andtreatment costs, with the recovered tar used as fuel and sediment asbeneficial reuse material.Biosurfactant; coal tar;environmental; polycyclicaromatic hydrocarbons;polymer partitioning;polystyrene; remediationIntroductionFrom the early 1800’s to the mid-1950’s, manufactured gas plants (MGP) supplied light andheat for residential homes and industries. MGP sites are a persistent source of pollutionfrom coal tar (Abrams and Loague, 2000), which was released into soil and water bodies during operations. Some estimate that the number of MGP sites in need of remediation approximates 50,000 (Hatheway, 2011); thus, the cost of cleanup will be staggering. One example isa report from New York State, which estimates it will cost 3 billion to clean 250 coal tarsites. Since remediation costs of former utility sites are ultimately borne by consumers (Stein,2011), a more efficient, cost-effective process is needed.CONTACT Albert Robbat, Jr.albert.robbat@tufts.eduDepartment of Chemistry, Tufts University, 62 Talbot Avenue,Medford, MA 02155, USA.Color versions of one or more of the figures in this article can be found online at www.tandfonline.com/bssc. 2016 Taylor & Francis Group, LLC

Downloaded by [Tufts University] at 13:47 20 July 20162N. M. WILTON ET AL.The two most often employed strategies for MGP site remediation are dig-haul-landfilland dig-haul-thermal treatment. The first moves the contamination from one location toanother and does not eliminate the possibility of pollutants leaching into the subsurface(Anderson et al., 1987; LeBlanc et al., 2000). The second increases the carbon footprint(Cormier et al., 2006; McGowan et al., 1996). For sediments, both strategies generally relyon excavation and either mechanical or gravity dewatering of the mud. Typically, every cubicmeter of sediment results in 1.2 cubic meters of material shipped off-site due to stabilizingagent additions. Moreover, review of U.S. Environmental Protection Agency (USEPA)records indicates that the number of remediation projects stopped due to community complaints from odor and traffic is significant. For these reasons, remediation technologies thatallow on-site beneficial reuse of treated MGP sediment are desired.Bacteria (Shin et al., 2006; Zhang et al., 1997), fungi (Bhardwaj et al., 2013) and plants(Dai et al., 2013) produce biosurfactant compounds that significantly reduce the interfacialtension between hydrocarbon-based nonaqueous-phase liquids (NAPL) and water, therebyincreasing the bioavailable material (Cameotra and Bollag, 2003; Coppotelli et al., 2010;Peng et al., 2015) compared to synthetic surfactants (Pei et al., 2010). Although the vastmajority of these compounds are produced biosynthetically (Cameotra et al., 2010), othersare produced or extracted from renewable feedstocks, e.g., red ash trees (Blythe, 2015; Guoet al., 2007). These chemicals are amphiphilic due to their fatty acid, protein or peptide content (Dwyer et al., 2014; Schaller et al., 2015; Silva et al., 2014).Biosurfactants have been investigated and found to be relatively “green” compared to synthetic surfactants because they are biodegradable and less toxic (Mulligan, 2005). Whilepetroleum remediation has been extensively investigated (Silva et al., 2014), few studies havefocused on using biosurfactants to remediate coal tar sites. For example, Garcia-Junco et al.(2003) found biosurfactants greatly enhanced the solubilization of PAH into the aqueousphase from a model NAPL. Sliwka et al. (2009) evaluated the effectiveness of rhamnolipidsfrom Pseudomonas aeruginosa to degrade residual coal tar, achieving a 28% reduction over14 days. Khanna et al. (2011) studied the effects of Bacillus spp. found in coal tar-impactedsoil. Using pyrene as an indicator of PAH reduction, a 56% decrease in concentration wasobtained over a 4-day period. Bezza and Chirwa (2016) reported an 86% reduction in PAHin a creosote-contaminated soil in a bio-slurry reactor over 45 days using a biosurfactantisolated from P. aeruginosa. Despite their promise, biosurfactants are expensive compared tosynthetic ones are not usually cost-competitive with dig-and-haul remediation of NAPLcontaminated sites (Marchant and Banat, 2012).Two-phase partition reactors using solid polymer sorbents and mobilizing agents havebeen found to increase ex situ separation efficiencies of contaminants from solids (Parentet al., 2012; Rehmann and Dagulis, 2007; Tomei et al., 2013, 2014). Critical to the success oftwo-phase polymer partition systems are the properties of the polymer, the concentration,volume, and ability of the surfactant to liberate organics from sediment/soil, and the contacttime between pollutant and polymer. While researchers have studied the biodegradation ofpolymer-sorbed contaminants, none have utilized a biosurfactant as the mobilizing phase inthe soil treatment step. Yeom et al. (1996) treated coal tar-impacted soil with Brij 30 surfactant and Tenax [poly(2,6-diphenyl-p-phenylene oxide) polymer]. After 12 days, phenanthrene concentrations decreased by 25%. In contrast, Rehmann et al. (2008) reported 80%removal of phenanthrene, fluoranthene and pyrene from fortified sediments in 2 days using30% isopropanol and polyurethane beads. The contaminant-sorbed beads were then

Downloaded by [Tufts University] at 13:47 20 July 2016SOIL AND SEDIMENT CONTAMINATION3biodegraded, regenerating them for another batch. Peyda et al. (2013) constructed a responsesurface model to study the removal of petroleum from a fortified soil using a 2-propanol/polyurethane bead system. Eighty percent extraction efficiency was achieved in 3 days.This study reports the results of a new, high-throughput, crop-based biosurfactant/polystyrene foam reactor system. The biosurfactant, CT1, is a complex mixture of plantpolypeptides and fat. According to test protocols established by the USEPA (2002), themixture is nontoxic for fresh (Daphnia magna and Pimephales promelas) and salt(Mysidopsis bahia and Menidia beryllina) water organisms. When CT1 is used withpolystyrene, coal tar rapidly emulsifies and then adsorbs onto polystyrene due to strongp–p interactions between aromatics in the tar and the polymer. Mass balance experiments indicate removal rates for bulk tar were the same as that of aromatics. Polystyrene foam is an appealing engineering solution for heavy oils and tars because it floatsin water and is easily recovered from the agitation vessel along with sorbed hydrocarbons. It is also an attractive alternative to other solid polymer adsorbents since recycledmaterial can be used. Toward this end, a response surface model was developed to optimize the biosurfactant/polymer system. The reactor yielded 80% coal tar recoveryfrom highly aged river sediment in 2 hr.ExperimentMaterialsCoal tar contaminated sediment was obtained from the Grand Calumet River in June 2013.The manufactured gas plant operated on the banks of the river from 1901 to 1950. Highconcentrations of tar persist in the sediment to this day. The river bottom was collected byback hoe and placed into a 10-m3 rolloff for testing. Approximately 200 L of sediment wasshipped to Tufts University for further study. The biosurfactant, CT1 was obtained fromGreenStract, LLP (New York, NY). CT1 is a mixture of proteins and polypeptides extractedfrom corn gluten meal and hemp. Corn gluten meal is a protein-rich feed, containing about65% crude protein, used as a source of protein and energy for livestock and fish. Hemp proteins serve a variety of functions in the human body, including the supply of amino acids forthe growth and maintenance of body tissue. CT1 is biodegradable, highly digestible, andwhen tested by an independent lab was found nontoxic for fresh and saltwater organismsused by the USEPA to determine suitability for remediation projects (report supplied uponrequest). Polystyrene home insulation panels (density D 20 kg/m3) were purchased from alocal hardware store. The panels, containing 30% recycled material, were ground to makepolystyrene foam pellets (PFPs, 3–10 mm in diameter).Analytical grade dichloromethane and toluene were purchased from VWRTM (Radnor,PA). Calibration mix #5 (the 16 USEPA priority pollutant PAH), internal standard mix(acenaphthene-d10, chrysene-d12, 1,4-dichlorobenzene-d4, naphthalene-d8, perylene-d12, andphenanthrene-d10), surrogate mix SOM01.1 (2-methylnaphthalene-d12, and fluoranthened12), and copper granules were obtained from Restek (Bellafonte, PA). Polypropylene syringes, 12 mL, and fiber glass filter tips, 1 mM, were obtained from MicroLiter Analytical Supplies, Inc. (Suwanee, GA) and Tisch (Cleves, OH), respectively. Whatman #1 filter paper90 mm was purchased from GE Healthcare (Pittsburgh, PA). Hydromatrix drying agent waspurchased from Agilent Technologies (Santa Clara, CA).

4N. M. WILTON ET AL.Sample preparationTo model the biosurfactant-enhanced polymer partition process, 10 g of sediment was sealedin 4-oz glass jars with known amounts of CT1 and PFP, for details see Table 1. Duct tape wasapplied to the outer surface of each jar to increase friction. The sample was agitated at90 rpm using a fixed speed dual drum rotary rock tumbler from Harbor Freight Tools(Calabasas, CA). After mixing, the supernatant was skimmed to collect PFP using a 16 meshscreen. After collection, PFP was gently sprayed with water to wash soil particles from thesurface. After the solids settled, CT1 and wash water were decanted from the “cake” thatformed at the bottom of the jar. Before gas chromatography/mass spectrometry (GC/MS)and total organic carbon (TOC) analysis, »1 g of cake was dried in an oven overnight at90 C to determine the dry weight of the sediment.Downloaded by [Tufts University] at 13:47 20 July 2016Table 1. Experimental conditions and results of PAH extracted from coal tar impacted 21222324a24b24c2526a26b26c272829Mvolume:Smass (mL/g)CT1 Conc (%)PFPmass:Smass (g/g)Mixing time (hr)% Removal1 (¡1)1 (¡1)1 (¡1)1 (¡1)2 (0)1 (¡1)1 (¡1)1 (¡1)1 (¡1)1 (¡1)1 (¡1)1 (¡1)1 (¡1)1 (¡1)2 (0)2 (0)2 (0)2 (0)2 (0)1 (¡1)1 (¡1)2 (0)2 (0)3 (1)2 (0)3 (1)3 (1)3 (1)3 (1)3 (1)3 (1)3 (1)3 (1)2 (0)1 (¡1)2.5 (0.5)2 (1)2 (1)2 (1)2 (1)1 (0)0.1 (¡0.9)0.5 (¡0.5)0 (¡1)2 (1)2 (1)2 (1)2 (1)1 (0)0.5 (¡0.5)0.5 (¡0.5)2 (1)2 (1)2 (1)2 (1)0 (¡1)2 (1)0 (¡1)0 (¡1)0 (¡1)2 (1)0 (¡1)2 (1)2 (1)2 (1)0 (¡1)2 (1)2 (1)2 (1)2 (1)2 (1)2 (1)0.065 (1)0.065 (1)0.065 (1)0.065 (1)0.065 (1)0.065 (1)0.065 (1)0.065 (1)2.2 10¡3 (¡0.93)4.3 10¡3 (¡0.87)0.022 (¡0.33)0 (¡1)0.043 (0.33)0.043 (0.33)0.065 (1)0.065 (1)0.065 (1)0.065 (1)0.022 (¡0.33)0 (¡1)0 (¡1)0.065 (1)0 (¡1)0.033 (0)0 (¡1)0 (¡1)0.065 (1)0.065 (1)0.065 (1)0.065 (1)0.065 (1)0.065 (1)0.065 (1)0.1300.065 (1)0.065 (1)0.5 (¡1)1 (¡0.33)2 (1)2 (1)2 (1)2 (1)2 (1)2 (1)2 (1)2 (1)2 (1)2 (1)1 (¡0.33)0.5 (¡1)2 (1)2 (1)2 (1)2 (1)1 (¡0.33)0.5 (¡1)0.5 (¡1)0.5 (¡1)2 (1)2 (1)2 (1)0.5 (¡1)0.5 (¡1)0.5 (¡1)0.5 (¡1)1.5 (0.33)2 (1)2 (1)2 (1)2 (1)102 s:1) % Recovery D ([initial] – [final])/[initial] 100.2) ¡1 (minimum) to 1 (maximum) codified model variables.3) Experiments 27–29 were not used to determine the model.4) In Experiment 29, CT1 was recycled and fresh PFP was used to treat the same sediment twice at optimum model conditions.

Downloaded by [Tufts University] at 13:47 20 July 2016SOIL AND SEDIMENT CONTAMINATION5To determine extraction efficiency by GC/MS, an automated pressurized liquid extractionand solvent evaporation system from Fluid Management Systems (Watertown, MA) wasused to extract the samples (Robbat and Wilton, 2014). Twenty microliters of 2000 mg/mLsurrogate solution in dichloromethane was injected onto 2 g sediment. The sediment wasmixed with 2 g Hydromatrix and added to a 40-mL extraction cell; the remaining deadvolume of the cell was filled with Hydromatrix. The system was programmed to deliver solvent to the extraction cell at 20 mL/min for 2.4 min and then pressurize to 1500 psi over2.5 min. The pressurized cell was heated to 120 C in 5 min. The temperature and pressurewere held constant for 20 min before the cell was allowed to cool to room temperature over20 min, and then depressurized. Solvent was flushed through the cell at 20 mL/min for1.3 min before N2 gas purged the residual solvent. Extracts were delivered to the evaporationunit and concentrated to »2 mL in the presence of 2 g copper granules to remove elementalsulfur. The evaporation unit was programmed to heat the extract to 65 C under 12 PSI ofN2. Sample extracts were passed through a polypropylene syringe fitted with 1 mM fiber glassfilters along with solvent washes to remove any remaining fines. The final extract volumewas approximately 3–4 mL.Mass balance experiments were performed to assess total solvent extractable materials(TSEM). Three samples, each of untreated and treated sediment, were dried and then groundto a fine powder in a mortar and pestle. For the TSEM experiments, the sediment was treatedunder optimum model conditions. All samples, 4 g each, were extracted 5 times for 10 minwith 10 mL of a 1:1 toluene/dichloromethane mixture using a Branson 5200 UltrasonicCleaner (Danbury, CT). The extracts were filtered, concentrated under a gentle stream ofnitrogen, and then baked overnight at 90 C to evaporate residual solvent, with the remainingtar mass weighed.To evaluate extraction efficiency in the field, a 0.25-m3 cement mixer, operating at90 rpm, was used to agitate CT1, sediment, and PFP. A total of 25 kg of river sediment wasused in each experiment. Field experiment 16 (Table 1) was replicated to assess operationalscalability. A 2% CT1 solution was added to the cement mixer at a mobile phase volume(Mvolume) to sediment mass (Smass) ratio of 2:1. PFP was added at a ratio of 0.022:1 g/g(PFPmass:Smass) to the sediment and mixed for 1 hr. After agitation, PFP floated to the top ofthe mixer and were removed via slotted shovel. The suspended fines were collected in 16-ozjars, sealed, and shipped to Tufts for analysis. The settled particles formed a “cake” overnight. After decanting the supernatant, PAH analysis was performed on the remaining solidsas previously described.EquipmentA Vario MICRO cube analyzer from ElementarTM (Hanau, Germany) was used to measureTOC in the sediment. A Shimadzu (Columbia, MD) model QP2010C GC/MS was used toanalyze the samples. Helium gas served as the carrier gas at 100 kPa head pressure. About1-mL sample injections were made. The high-temperature fused silica Rxi-5MS column(30 m 0.25 mm 0.25 mm) was obtained from RestekÒ . The GC was temperature programmed as follows: 60 C for 1 min, 6.5 C/min to 320 C, and hold for 5 min. The inlet,interface, and ion source were maintained at 320 C, 280 C, and 230 C, respectively. The MSwas operated in full-scan mode from m/z 50 to 350. Ion Analytics (Andover, MA) spectraldeconvolution software was used to analyze the data.

6N. M. WILTON ET AL.Before and after extraction treatment, images of PFP were taken using a Phenom Prodesktop scanning electron microscope (SEM). Carbon tape was used to affix the sample tothe holder. Dust was removed with Dust-OffÒ cleaner before loading samples into theinstrument. All samples were imaged without sputter-coating in the charge-up reductionmode.Experimental designMatlab was used to model the extraction efficiency of the system. The four variables testedwere Mvolume:Smass (X1), CT1 concentration (X2), PFPmass:Smass (X3), and mixing time (X4).The model below provides information on both individual variables and their interactionsY D b0 C b1 X1 C b2 X2 C b3 X3 C b4 X4 C b12 X1 X2 C b13 X1 X3 C b14 X1 X4 C b24 X2 X4Downloaded by [Tufts University] at 13:47 20 July 2016C b34 X3 X4 C b11 X1 2 C b22 X2 2 C b33 X3 2 C b44 X4 2Experiments 1–16, 27 and 28 were used to determine the min (¡1) and max (1) values of themodel under field-practical conditions: X1 D 1–3 mL/g; X2 D 0–2% active ingredient; X3 D 0–0.065 g/g; and X4 D 0.5–2.0 hr. Given these initial experiments, we used the D-Optimal experimental design approach to find the subset of experiments that leads to the highest determinantof the information matrix, which corresponds to the smallest variance of the coefficients in themodel. The D-Optimal approach, combined with the 16 original experiments, reduced the number of remaining experiments required in the model. In order to compare subsets with differentnumbers of experiments, the normalized determinant M D det/np was taken into account, wheren is the number of experiments and p is the number of parameters to be estimated. When thenumber of experiments increases, both the numerator (quality of information) and the denominator (experimental effort) increase. The normalized determinant weights the quality of theinformation, expressed as the variance of the coefficients in the model, by the experimental effort.From this, nine additional experiments were needed to improve model accuracy. These experiments are listed in Table 1 as 17–25. Experiments 15, 24 and 26 were

sites. Since remediation costs of former utility sites are ultimately borne by consumers (Stein, 2011), a more efficient, cost-effective process is needed. CONTACT Albert Robbat, Jr. albert.robbat@tufts.edu Department of Chemistry, Tufts

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