Journal of the Energy Institute xxx (2016) 1e10

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Phytoremediation as an effective method to remove heavy metalsfrom contaminated area e TG/FT-IR analysis results of the gasificationof heavy metal contaminated energy crops

Sebastian Werle a, *, Daniel Bisorca b, Anna Katelbach-Wo�zniak a, Marta Pogrzeba c,Jacek Krzy _zak c, Izabela Ratman-Kłosi�nska c, Daniela Burnete b

a Institute of Thermal Technology, Silesian University of Technology, Konarskiego 22, 44-100, Gliwice, Polandb Institutul de Studii si Proiect�ari Energetice, Lacul Tei 1-3, 020371, Bucharest, Romaniac Institute for Ecology of Industrial Areas, Kossutha 6, 40-844, Katowice, Poland

a r t i c l e i n f o

Article history:Received 9 October 2015Received in revised form25 March 2016Accepted 4 April 2016Available online xxx

Keywords:TGA analysisFT-IR analysisHeavy metals contaminated energy crops

* Corresponding author. Tel.: þ48 322 372 983; faxE-mail address: sebastian.werle@polsl.pl (S. Werle

http://dx.doi.org/10.1016/j.joei.2016.04.0021743-9671/© 2016 Energy Institute. Published by Else

Please cite this article in press as: S. Werle, eTG/FT-IR analysis results of the gasification o10.1016/j.joei.2016.04.002

a b s t r a c t

Thermal Analysis determines a set of methods for the study of the selected physical properties of thesubstance under the influence of temperature or atmosphere. Thermogravimetric (TG) analysis is veryuseful for studying the kinetics of gasification processes. However, by itself TG does not allow the directidentification of the gases released from the sample during the thermal treatment. For this purpose,coupling TG to a spectroscopic interrogation method, such as Fourier-Transform-Infrared (FT-IR) spec-troscopy, is an excellent solution. The objective of this paper is to ascertain the usefulness and limitationsof TG-FTIR technique in the study of biomass gasification and to determine gasification product evolutionpatterns and yields for heavy metal contaminated (HMC) samples of Miscanthus x giganteus, Sida her-maphrodita, Spartina pectinata and Panicum virgatum. In experiments reported in this paper, biomasssamples were heated at 10� C min�1 in a nitrogen environment and the volatile products were sweptimmediately into a cooler gas cell, which minimized secondary reactions. Process products werequantitatively analysed by gas-phase Fourier transform infrared (FT-IR) spectroscopy. This gas analysiscombined with weight loss measurements of the heated material ensured generally good mass-balanceclosure. The paper discusses the techniques employed to identify the evolved products and presents theproduct evolution patterns and yields.

© 2016 Energy Institute. Published by Elsevier Ltd. All rights reserved.

1. Introduction

1.1. Heavy metal emission in Europe

Among themany heavymetals released fromvarious products and processes, cadmium, lead andmercury are of great concern to humanhealth because of their toxicity and their potential to cause harmful effects at low concentrations and to bioaccumulate. Significant progresshas been made in reducing emissions to air of these metals in Europe with 1995 emissions being about 50% of 1990 levels and decreasingfurther to 40% by 1999. Lead emissions in 1999 were down to about 17,000 tonnes/year and mercury and cadmium to 200 and 400 tonnes/year, respectively [1]. Although controlling diffuse emissions of cadmium and mercury remains problematic (e.g. batteries), point sourceemissions of these metals have declined as a result of improvements in sectors such as wastewater treatment, incinerators and the metalssector [2]. Factors contributing to this include large decreases of lead emissions from the transport sector following the introduction ofunleaded petrol in the early 1990s [3], continuing moves away from the use of lignite in the eastern European energy sector, and theintroduction of improved pollution abatement technologies across a range of industrial and waste treatment sectors.

: þ48 322 372 872.).

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t al., Phytoremediation as an effective method to remove heavy metals from contaminated area ef heavy metal contaminated energy crops, Journal of the Energy Institute (2016), http://dx.doi.org/

S. Werle et al. / Journal of the Energy Institute xxx (2016) 1e102

A number of recent policy initiatives have been introduced at the international level to address concerns raised by heavy metal emis-sions. The United Nations Economic Commission for Europe (UNECE) Convention on Long-Range Transboundary Air Pollution (CLTRAP)1998 Aarhus protocol on heavy metal targets cadmium, lead and mercury and requires countries to reduce their emissions of these threemetals to below their 1990 levels (or an alternative year between 1985 and 1995). The need for further global initiatives onmercury has alsobeen highlighted. Some European countries have success in reducing emissions of this metal through a combination of substitution, e.g. ofmercury cells used in chlorine production, and improvement in abatement technologies, especially flue-gas cleaning.

1.2. Heavy metal contaminated areas

Soil contamination creates a significant risk to human health; heavy metals from industrial waste contaminate drinking water, soil,fodder, and food. Contaminated sites could pose significant environmental hazards for terrestrial and aquatic ecosystems as they areimportant sources of pollution which may result in ecotoxicological effects. Soil contamination is mainly located close to waste landfills,industrial/commercial activities diffusing heavy metals, oil industry, military camps, and nuclear power plants. During the past decades, thelarge volume of waste and the intense use of chemicals have resulted in numerous contaminated sites across Europe, the major causes beingmunicipal and industrial wastes with 38% as well as the unsustainable production of rawmaterials, production and distribution processes ofthe industrial and commercial sectors with 34% [4]. Themost prevalent types of soil contaminants in Europeemineral oils and tracemetals,including lead, arsenic, cadmium, andmercury, heavymetals, including lead, arsenic, cadmium, andmercurye together contribute to 60% ofsoil contamination (Fig. 1). More than 2.5 million sites among 38 European countries are potentially contaminated, and 342,000 sites havebeen identified as contaminated [4]. The number of recorded polluted sites across Europe is expected to increase by 50% by 2025 [5].Remediation remains still a significant undertaking as only about 80,000 sites have been remediated. Most EU countries have now legis-lation in place to control industrial wastes and accidents.

1.3. Methods of remediation of HMC areas

Phytoremediation is one of the techniques used for remediation of contaminated areas and could be applied both to organic andinorganic contaminants. A wide range of plants has the potential to be used in phytoremediation techniques, such as sunflowers, hybridpoplars, willow, grasses, cottonwood, mulberry, etc. The utilization of these biomass can be generallymade from two types of processes, bio-chemical conversion and thermal conversion. Biochemical conversion methods are fermentation and anaerobic digestion, while thermalmethods are combustion, gasification and pyrolysis. An approach to carry out the processes varies, depending on the desired products of theprocess, but the primary aim is the transformation of the biomass into fuel.

Based on the seven-year field tests carried out by Institute for Ecology of Industrial Areas (IETU) it was recognized that some conventionalenergy crops such as Miscanthus x giganteus, Sida hermaphrodita, Spartina pectinata, Panicum virgatum are characterized by the huge po-tential of the heavy-metal uptake capacity and e simultaneously e potential for biomass production for energy purposes. Additionally, inprevious works [6e9] it was concluded that the analysed energy crops are characterized by the yield equal to: 11.7 Mg/ha in the case of S.hermaphrodita, 9.5 Mg/ha in the case of S. pectinata, 15.0 Mg/ha in the case of Miscanthus x giganteus and 13.3 Mg/ha in the case of P. vir-gatum. Phytoremediation results shows [10] thatMiscanthus x giganteus is a more tolerant species to the total contaminated soil with Zn andPb to S. hermaphrodita. Additionally, it was proven in [11] that S. pectinata and P. virgatum are also very suitable for heavy metalsphytostabilization.

Thermal Analysis determines a set of methods for the study of the selected physical properties of the substance under the influenceof temperature or atmosphere. Thermogravimetric (TG) analysis is very useful for studying the kinetics of gasification processes.

Fig. 1. Distribution of contaminants affecting soil in Europe (BTEX: benzene, toluene, ethylbenzene, and xylenes; CHC: chlorinated hydrocarbon; PAH: polycyclic aromatic hy-drocarbon) [4].

Please cite this article in press as: S. Werle, et al., Phytoremediation as an effective method to remove heavy metals from contaminated area eTG/FT-IR analysis results of the gasification of heavy metal contaminated energy crops, Journal of the Energy Institute (2016), http://dx.doi.org/10.1016/j.joei.2016.04.002

S. Werle et al. / Journal of the Energy Institute xxx (2016) 1e10 3

However, by itself TG does not allow the direct identification of the gases released from the sample during the thermal treatment. Forthis purpose, coupling TG to a spectroscopic interrogation method, such as Fourier-Transform-Infrared (FT-IR) spectroscopy, is anexcellent solution. The objective of this paper is to ascertain the usefulness and limitations of TG-FTIR technique in the study of biomassgasification and to determine gasification product evolution patterns and yields for heavy metal contaminated (HMC) samples ofMiscanthus x giganteus, S. hermaphrodita, S. pectinata and P. virgatum. In experiments reported in this paper, biomass samples wereheated at 10� C min�1 in a nitrogen environment and the volatile products were swept immediately into a cooler gas cell, whichminimized secondary reactions. Process products were quantitatively analysed by gas-phase Fourier transform infrared (FT-IR) spec-troscopy. This gas analysis combined with weight loss measurements of the heated material ensured generally good mass-balanceclosure. The paper discusses the techniques employed to identify the evolved thermal treatment products and presents the productevolution patterns and yields.

2. Materials and methods

2.1. Samples preparation

The experimental plots were established on contaminated arable land located in Bytom (southern part of Poland, Silesian Voivodeship).The experimental field (0.25 ha) was divided into subplots with buffer zone 6m. General view of the field with the energy crops is presentedin Fig. 2.

The site characteristic is presented in Table 1.In Silesian Voivodeship, 5e10% of agricultural soils are contaminated with cadmium, lead and zinc [11]. This contamination is the legacy

of mining and smelting industry of Zn, Pb and Cd ores located in these regions [12]. Cultivation of energy crops on contaminated agriculturalareas might lead to excess of metals in plant tissues and reemissions of contaminants into the atmosphere during biomass impropercombustion [13]. Environmental risk resulting from high content of heavy metals (especially Cd) in combustion residues [14] is the otherissue. The plots were established in the near proximity of a closed-down lead/zinc/cadmium ore mining and processing plant. Themetallurgical complex was in operation for more than 100 years and had significant impact on local soils. Recently the land was used forgrain crop production (especially wheat farming). At the end of each growing season shoot samples of all crops was collected. Picture of thesamples to experiments are presented in Fig. 3.

2.2. Experiment conditions

The experiment was carried out using TGA equipment e Netzsch STA 409 Thermogravimeter and Spectrum GX Perkin Elmer spec-trometer. Thermogravimeter (TG) consists of (i) the high sensitivity weight, (ii) furnace which allows the sample heating up (10 K/min) to atemperature equal to 1500 �C and (iii) a gas dispensing system. TG/FTIR measurement is carried out in an inert gas atmosphere. The gasvolumetric flow rate was equal to 80 ml/min. The initial sample mass with fraction less than 1 mmwas equal to 10 mg. The biomass sampleis weighted on the outer weight model Radwag WAS 220/C/2 with an accuracy of 0.1 mg.

Simultaneously with TG measurements, differential thermal analysis (DTG) can be determined. DTG method can be used to test sub-stances which are susceptible to various exothermic or endothermic transitions. It allows the effects of thermal characteristic of a givensubstance to its identification and determination of its content.

Fig. 2. General view of the field with the energy crops.

Please cite this article in press as: S. Werle, et al., Phytoremediation as an effective method to remove heavy metals from contaminated area eTG/FT-IR analysis results of the gasification of heavy metal contaminated energy crops, Journal of the Energy Institute (2016), http://dx.doi.org/10.1016/j.joei.2016.04.002

Table 1The site characteristic.

Property Value

pH (1: 2.5 soil/KCl ratio) 6.79 ± 0.01Electrical conductivity (mS/cm) 127 ± 0.002Organic matter content (%) 4.0 ± 0.03Sand (1e0.05 mm), % 28Silt (0.05e0.002 mm), % 56Clay (<0.002 mm), % 16Total heavy metal concentration (extraction with aqua regia)Pb (mg kg�1) 547.0 ± 27.92Cd (mg kg�1) 20.84 ± 1.17Zn (mg kg�1) 2174.5 ± 103CaCl2 extractable metal fractiona

Pb (mg kg�1) 0.39 ± 0.03 (0.07)b

Cd (mg kg�1) 1.20 ± 0.03 (5.76)b

Zn (mg kg�1) 46.52 ± 1.51 (2.13)b

Values represent mean of three replicate samples ± SE.a Extraction with 0.01 M CaCl2.b in parentheses percentages of total metal concentrations are presented.

Fig. 3. Feedstock samples for TGA/FTIR analyses.

S. Werle et al. / Journal of the Energy Institute xxx (2016) 1e104

3. Results and interpretation

3.1. TG analysis

Lignocellulosic biomass consists of three main constituents: cellulose, hemicellulose and lignin. All of the analysed feedstock is char-acterized by different chemical structure. Due to this fact, on the Fig. 4, analysis of the mass losses and DTG as a function of the time ispresented.

In order to classify the type of the reaction which takes place in the process, the graph can be divided into 3 regions. The first region isdefined between the value of the temperature between the starting point of the TGA analyses and the temperature value equal to 150 �C. Itcan be assumed that it corresponds to the loss of water and light volatile compounds in the biomass sample. The dehydration is slightlyhigher for S. hermaphrodita and S. pectinata that for Miscanthus x giganteus and P. virgatum.

The second region is themost important for analysis defined between the temperature value equal to 150 �C and 450 �C. In that range thegreatest weight loss of the samples occurs. It is the region, where active pyrolysis and gasification take place. As other studies have shownthis region corresponds to the decomposition of cellulose and hemicellulose and partial loss of lignin in the biomass samples. It can beclearly seen, that Miscanthus x giganteus presents the highest reactivity of the four samples, with a peak 0.105%/min at 350 �C. This isconsistent with literature [15]. The other 3 samples exhibited very similar reactivity peaks (see Table 2), but S. hermaphrodita had a lowerpeak temperature, 336 �C, than S. pectinata and P. virgatum, 345 �C. Analysing this Figure it can be also concluded that S. pectinata and P.virgatum present a shoulder around 300 �C, which corresponds to the hemicellulose decomposition. The third region is defined above thetemperature value equal to 450 �C. It shows the slow decomposition of lignin.

3.2. FTIR analysis

FTIR is a technique, which can be used for qualitative identification of a number of organic and inorganic compounds by selective ab-sorption of radiation in the infrared range. It uses a chemical's particle's ability to absorb infrared radiation energy quantum. As a result the

Please cite this article in press as: S. Werle, et al., Phytoremediation as an effective method to remove heavy metals from contaminated area eTG/FT-IR analysis results of the gasification of heavy metal contaminated energy crops, Journal of the Energy Institute (2016), http://dx.doi.org/10.1016/j.joei.2016.04.002

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

-0.11

-0.09

-0.07

-0.05

-0.03

-0.01

0.01

50 100 150 200 250 300 350 400 450 500 550 600 650 700 750 800

Mas

s [%

/min

.]

DTG

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in.]

Temperature [°C]

DTG&Mass vs. Temperature

Miscanthus x giganteus Panicum virgatum Sida hermaphroditaSpar na pec nata Miscanthus x giganteus Panicum virgatumSida hermaphrodita Spar na pec nata

Fig. 4. DTG and mass loss changes as a function of temperature for all analysed feedstock.

Table 2The DTG values of the analysed feedstock.

Sample DTG peak, �C DTG max, %/min Solid residues, %, wet basis

Miscanthus x giganteus 350 0.1050 4.71Panicum virgatum 345 0.0927 11.66Sida hermaphrodita 336 0.0980 7.84Spartina pectinata 345 0.0980 7.51

Table 3Characteristic absorption bands of analysing feedstock samples.

Miscanthus x giganteus Sida hermaphrodita Panicum virgatum Spartina pectinata

OH (cm�1) 3342; 663 3343; 658 3338; 1637; 658 3338; 670CH2 from saturated

compound (cm�1)2917; 1458; 1370; 1241; 614 2917; 2850; 1456; 1371; 1242; 610 2918; 2851; 1424; 1369; 1244; 611 2918; 2850; 1463; 1370; 615

C¼O (cm�1) 1730 1735 1731 1734Aromatic ring (cm�1) 1603; 1506; 897; 833 1597; 1504; 894; 832 1602; 1515; 898; 832 1610; 1505; 899CeCeOe (cm�1) 1159; 1031 1159; 1036 1159; 1033 1156; 1035

Table 4Characteristic absorption bands of analysing solid residue (ash) samples.

Plant Miscanthus x giganteus Sida hermaphrodita Panicum virgatum Spartina pectinata

Silicate (cm�1) 3618; 1109; 670; 619 3678; 3641; 1116; 670; 616 3728; 3619; 1152; 679; 611 3709; 3589; 670NH2 Group (cm�1) 3198 3093 3236 3197Sulphate (cm�1) 1039 1054 1052 1055Chlorine (cm�1) 744 746 750 746Carbonate (cm�1) 874 873 874 876

S. Werle et al. / Journal of the Energy Institute xxx (2016) 1e10 5

radiation energy oscillating-rotatingmolecules is increasing, which is reflected by an increase in the amplitude of the vibration. The result ofabsorbance and transmittance of the sample is the molecular fingerprint of the sample.

FTIR analysis made it possible to identify the presence of the individual major functional groups such as OeH, C]O, alkanes and specieslike CH4, CO2, CO. On the above mentioned graph the fingerprint region is also mentioned. It is the regionwhere it is very difficult to pick theindividual bond and every compound has a different pattern of troughs in this part of the spectrum.

For all analysed biomass samples the FTIR spectrumwere recorded andwere identified characteristic absorption bands presented Table 3.For all analysed ash samples the FTIR spectrum was recorded and identified characteristic absorption bands presented in Table 4.For all analysed liquid residues samples the FTIR spectrum was recorded and identified characteristic absorption bands presented in

Table 5.The Miscanthus x giganteus tar sample is degraded biomass by displacement of the bands from 2942 cm�1 and occurrence of the ab-

sorption band at 758 cm�1, specific to CH2 groups in unsaturated chain, 1711 cm�1, specific to acid group COOH, 1516 cm�1, specific to anacidic aromatic compound and to the attenuation and disappearance of bands from 1160 cm�1 to 950 cm�1, with displacement of amaximum of 1050 cm�1. Also, the following bands have appeared: 928 cm�1 specific to sulphate, 811 cm�1, 758 cm�1, specific to substitutedaromatic ring. Typical aromatics are classified in aromatic hydrocarbons (and derivates) and phenols (and derivates).

Please cite this article in press as: S. Werle, et al., Phytoremediation as an effective method to remove heavy metals from contaminated area eTG/FT-IR analysis results of the gasification of heavy metal contaminated energy crops, Journal of the Energy Institute (2016), http://dx.doi.org/10.1016/j.joei.2016.04.002

Table 5Characteristic absorption bands of analysing liquid residue samples.

Plant Miscanthus x giganteus Sida hermaphrodita Panicum virgatum Spartina pectinata

OH (cm�1) 3352 3356 3340 3338; 678NH2 (cm�1) e 3276 3239 3214; 1662; 678CH2 from unsaturated/Aromatic compound (cm�1) 2942; 758 2939; 756 2938; 761 2962; 2929; 752CH2 from saturated compound (cm�1) 1381; 1237; 605 1376; 1232; 605 1375; 1233; 608 1375; 1241; 607COOH (cm�1) 1711 1707 1707 1706Aromatic ring (cm�1) 1603; 892; 811 1604; 888; 782 1603; 1515; 890; 808 1603; 1505; 891; 808Aromatic acid compound (cm�1) 1516; 1050 1515; 1045 1515; 1047 1515; 1048SeOR (ester sulphate) (cm�1) 928 927 925 925

S. Werle et al. / Journal of the Energy Institute xxx (2016) 1e106

Sida hermaphrotita tar sample is degraded biomass, highlighted by shifting absorption bands to 2939 cm�1, and the occurrence of theabsorption band at 756 cm�1, specific to CH2 groups in unsaturated chain, 1707 cm�1, specific to acid group COOH, 1515 cm�1, specific to anaromatic acid compound, with the disappearance or attenuation of bands from 1160 cm�1 to 950 cm�1, with the maximum shifted at1045 cm�1, specific to an aromatic acid compound. Also, it is noticed the occurrence of absorption bands: at 927 cm�1, specific to estersulphate, 888 cm�1, 782 cm�1, specific to substituted aromatic ring.

The P. virgatum tar sample is degraded biomass, highlighted by shifting absorption bands at 2938 cm�1 and by the occurrence of theabsorption band at 761 cm�1, specific to CH2 groups in unsaturated chain, 1707 cm�1, specific to acid groupeCOOH,1515 cm�1, specific to anaromatic acid compound, with the disappearance or attenuation of bands from 1160 cm�1 to 950 cm�1, with the maximum shifted at1047 cm�1, specific to an aromatic acid. Also, it is noticed the occurrence of absorption bands: 925 cm�1, specific to ester sulphate, 808 cm�1

and 761 cm�1, specific to substituted aromatic ring. Be noticed the presence of eNH2, specific amine group at 3239 cm�1.In case of S. pectinata, the tar sample is degraded biomass, highlighted by shifted absorption bands at 2962 cm�1, and by the occurrence of

the absorption band at 2929 cm�1, 758 cm�1, specific to CH2 groups in unsaturated chain,1706 cm�1, specific to acid group COOH,1515 cm�1,specific to an aromatic acid compound, with the disappearance or attenuation of bands from 1160 cm�1 to 950 cm�1, with the maximumshifted at 1048 cm�1, specific to an aromatic acid. Also, it is noticed the occurrence of absorption bands: 925 cm�1, specific to ester sulphate,891 cm�1 and 808 cm�1, specific to substituted aromatic ring. Be noticed the presence of eNH2, specific amine group at 3214 cm�1,1662 cm�1 and 678 cm�1. In Fig. 5 the FTIR spectrums for Miscanthus x giganteus, S. hermaphrodita, P. virgatum and S. pectinata tar samplesare presented.

All the biomass samples contains clusters of wooden structure, with approximately equal amounts of cellulose, with the largest amountof lignin in the samples of S. pectinata and Mischantus x giganteus, which gives a greater mechanical strength but also a higher chemicalreactivity of these samples. Also Sida hermaphrodita biomass sample presents the highest amount of silicates, and the highest amount ofsaturated organic compounds has S. pectinata biomass sample.

In Fig. 6 the FTIR spectrums for Miscanthus x giganteus, S. hermaphrodita, P. virgatum and S. pectinata tar samples are presented.All the tar samples contain degradation products of biomass highlighted by the appearance of CH2 groups in unsaturated chain or from

aromatic compound. The highest quantity being in S. pectinata, followed by P. virgatum, Miscanthus x giganteus and S. hermaphrodita.All the samples contain organic acids. The highest quantity was determined for S. pectinata, followed by P. virgatum, S. hermaphrodita and

Miscanthus x giganteus.Saturated products were determined for all the samples, with large amounts for S. hermaphrodita,Miscanthus x giganteus and S. pectinata.Aromatic acid compounds were found for Miscanthus x giganteus and S. hermaphrodita tar samples, while for P. virgatum the aromatic

acid compounds were found in a very small amount, almost missing.Sulphate esters were found in all the four samples. The amine compounds were found in all the samples, but in higher quantities for S.

pectinata and P. virgatum. Silicate was found in all the samples, with higher quantities for P.anicum virgatum and S. pectinata, while for S.hermaphrodita and Miscanthus x giganteus the quantity was lower.

In Fig. 7 the FTIR spectrums for Miscanthus x giganteus, S. hermaphrodita, P. virgatum and S. pectinata ash samples are presented.All the ash samples contain silicate, amine, sulphates, carbonates and chlorides.The ash samples in descending order of silicate content are: S. pectinata, S. hermaphrodita, P. virgatum and Miscanthus x giganteus.For the amine content, the samples were classified as follows: Miscanthus x giganteus, followed by S. pectinata, S. hermaphrodita and P.

virgatum. Regarding the sulphate content in the ash samples, the highest amount was found for S. pectinata, followed by Miscanthus xgiganteus and S. hermaphrodita and P. virgatumwith an approximately equal content. The carbonate content is higher for S. hermaphrodita incomparison toMiscanthus x giganteus. The lowest values of the carbonate are for P. virgatum. The highest amount of chloride was found forMiscanthus x giganteus, followed by S. pectinata, S. hermaphrodita and P. virgatum.

4. Conclusion

Phytoremediation is one of the techniques used for remediation of contaminated areas.The group of energy crops has taken into consideration include native and foreign species such as perennial dicotyledonous plants and

perennial grass species.Coupling TG to a spectroscopic interrogation method, such as Fourier-Transform-Infrared (FT-IR) spectroscopy, is an excellent and easy

solution for characterization quality of the biomass thermal treatment processes.All the analysed biomass samples contain clusters of wooden structure, with approximately equal amounts of cellulose. The largest

amount of ligninwas found in the samples of S. pectinata andMiscanthus x giganteus. This feature is very attractive taking into considerationquality (eg. gas composition) of the products after thermal decomposition of heavy metal contaminated biomass. This can be explained bythe fact that CO is mainly formed by the degradation of lignin during pyrolysis.

Please cite this article in press as: S. Werle, et al., Phytoremediation as an effective method to remove heavy metals from contaminated area eTG/FT-IR analysis results of the gasification of heavy metal contaminated energy crops, Journal of the Energy Institute (2016), http://dx.doi.org/10.1016/j.joei.2016.04.002

4000.0 3600 3200 2800 2400 2000 1800 1600 1400 1200 1000 800 550.0

cm-1

%T

Panicum virgatum

Miscanthus x giganteus

Sida hermaphrodita

Spartina pectinata

3726.93

3338.442918.48

2850.90

2326.292166.61

1980.29

1636.891601.50

1514.69

1424.341368.78

1316.83

1244.141158.91

1033.05

897.84

611.29

3732.47

3709.16

3342.312917.30

2341.842166.08

1979.311729.98

1602.761506.07

1457.79

1422.23

1369.54

1318.43

1240.78

1159.261031.15

897.47832.72

2849.60

3732.74

3337.83

2918.132849.92

2326.85

2162.54 1979.28

1733.76

1648.33

1515.29

1462.94

1369.67

1316.24

1035.46

796.74

582.10

3725.85

3706.11

3342.87

2917.332326.50

2166.971979.27

1734.85 1597.231504.98

1424.281371.20

1318.49

1241.56

1158.65

894.44 609.89

562.63

1036.45

2849.60

658.29

663.29614.29

3706.16

1730.76

615.291156.26

Fig. 5. FTIR spectrum for biomass samples.

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4000.0 3600 3200 2800 2400 2000 1800 1600 1400 1200 1000 800 570.0

cm-1

%T

Miscanthus x giganteus

Sida hermaphrodita

Spartina pectinata

Panicum virgatum

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3214.192962.46

1984.21

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925.02

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Fig. 6. FTIR spectrum for tar samples.

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10.1016/j.joei.2016.04.002

4000.0 3600 3200 2800 2400 2000 1800 1600 1400 1200 1000 800 550.0

cm-1

%T

Panicum virgatum

Miscanthus x giganteus

Sida hermaphrodita

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Fig. 7. FTIR spectrum for ash samples.

S.Werle

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Pleasecite

thisarticle

inpress

as:S.Werle,et

al.,Phytoremediation

asan

effectivemethod

torem

oveheavy

metals

fromcontam

inatedarea

eTG

/FT-IRanalysis

resultsofthe

gasificationofheavy

metalcontam

inatedenergy

crops,JournaloftheEnergy

Institute(2016),http://dx.doi.org/

10.1016/j.joei.2016.04.002

S. Werle et al. / Journal of the Energy Institute xxx (2016) 1e1010

The highest quantity of silicates was found in S. hermaphrodita biomass sample, and the highest amount of saturated organic compoundshas S. pectinata biomass sample.

All the tar samples contain organic acids, the highest quantity was determined for S. pectinata, followed by P. virgatum, S. hermaphroditaand Miscanthus x giganteus.

Saturated products were determined for all the samples, with larger amounts for S. hermaphrodita, Miscanthus x giganteus and S.pectinata.

During the process, the heavy metal contaminated biomass species are not only reduced inweight or volume, but concentrate the heavymetals in the ash fraction (mainly as a carbonates, silicates and sulphates interesting for recycling) is enlarged. Taking into consideration thisfact, the most attractive species for phytoremediation coupled with thermal utilization of produced biomass seems to be Miscanthus xgiganteus, followed by S. pectinata.

Acknowledgement

The paper has been prepared within the frame of the FP7-People-2013-IAPP (GA No610797) Phyto2Energy Project.

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Please cite this article in press as: S. Werle, et al., Phytoremediation as an effective method to remove heavy metals from contaminated area eTG/FT-IR analysis results of the gasification of heavy metal contaminated energy crops, Journal of the Energy Institute (2016), http://dx.doi.org/10.1016/j.joei.2016.04.002