iron oxide/polymer-based nanocomposite material for hydrogen sulfide adsorption applications

Iron Oxide/Polymer-Based NanocompositeMaterial for Hydrogen Sulfide AdsorptionApplications

The processing of iron oxide nanoparticles derived from spray flame synthesis forspecific adsorption applications is described. After the as-prepared particlesproved the ability for H2S removal in pure gas treatment, two different nanopar-ticle-based composite materials were prepared. While impregnation of activatedcarbon with the as-prepared nanoparticles showed the expected increase in H2Sadsorption capacities, a significant enhancement in desulfurization performancewas observed for a novel iron oxide nanoparticle composite material. H2S adsorp-tion was tested in fixed-bed breakthrough curve measurements. The H2S removalefficiency of the novel material under ambient conditions indicates highly promis-ing properties for potential use in industrial and air pollution control applications.

Keywords: Adsorption, Hydrogen sulfide removal, Iron oxide, Nanocomposite,Nanoparticles

Received: May 21, 2014; revised: July 18, 2014; accepted: August 21, 2014

DOI: 10.1002/ceat.201400303

1 Introduction

The reduction of sour emissions is an environmental issue ofspecial public interest in today’s air pollution control as well asin certain sectors of energy technology and chemical engineer-ing, e.g., fuel cells, oil refineries, or biogas upgrader [1, 2]. Inaddition, tightened environmental regulations force manufac-turers to meet lower threshold values in respect of pollutantsrelease. While the desulfurization of fossil fuels has achieved ahigh standard, fuel-cell applications and chemical synthesisbased on heterogeneous catalysis often require a deep desulfur-ization of the respective feedstock. Especially gaseous hydrogensulfide generates serious problems due to its corrosive andtoxic properties. Even minor concentrations cause damage topipelines and energy conversion sites or lead to poisoningeffects on industrial catalysts.Gas adsorption is a preferred technology in modern gas

phase purifying and separation processes. To meet low ppm-

specifications in product and/or exhaust gases, two differentroutes for adsorptive desulfurization are commonly applied.Physisorption on regenerable adsorbent materials like zeolitesor silica gels is widely used in cyclic working multistage plants[3–5]. A further discussion on state-of-the-art adsorbents isfeatured in [6]. Chemisorptive materials based on impregnatedactivated carbon or metal oxide-based scavengers [7] providemuch more adsorption capacity due to the chemical conversionof the sulfurous compounds. However, they are non- or poorlyregenerable and have to be disposed after use. Furthermore,impregnation can only be performed in low concentration andis attended by a significant decrease of surface area and porosi-ty or even pore blocking [8–12]. Hence, there is a great interestin optimizing existing or developing new adsorbents exceedingthe capacities of present adsorption equipment.A promising approach to meet these future needs is to make

use of nanoscale materials with their high surface-to-volumeratio and their mesoscopic properties. Their elevated reactivity[13] and the dominance of surface interactions [14] makenanoparticles ideal for adsorption applications. Particularlytransition metal oxides combine these attributes due to theirchemical potential towards polar gases [15, 16]. Iron oxides aswidely available materials meet many of the desired propertiesand consequently were chosen as the object of investigation[17]. The basic approach presented in this work is based on the

www.cet-journal.com ª 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim Chem. Eng. Technol. 2014, 37, No. 11, 1938–1944

Oliver Blatt1

Martin Helmich2

Bastian Steuten2

Sebastian Hardt1

Dieter Bathen2,3

Hartmut Wiggers1,4

1University of Duisburg-Essen,Institute for Combustion andGas Dynamics – Reactive Fluids,IVG, Duisburg, Germany.

2University of Duisburg-Essen,Chair of Thermal SeparationTechnology, Duisburg,Germany.

3Institute of Energy andEnvironmental TechnologyIUTA, Duisburg, Germany.

4University of Duisburg-Essen,Center for NanointegrationDuisburg-Essen, CENIDE,Germany.

Supporting Informationavailable online

–Correspondence: Martin Helmich ([email protected]), Uni-versity of Duisburg-Essen, Chair of Thermal Separation Technology,Lotharstraße 1, 47057 Duisburg, Germany.

1938 Research Article

utilization of iron oxide nanoparticles in combination with thelarge surface area of an activated carbon to achieve a micropo-rous material with huge amount of active adsorption sites forsulfurous species. Although the nanoparticles are expected toprovide a high chemical activity, they require a supporting,porous host material for immobilization and accessibility.The activity of iron oxide nanoparticles from spray flame

synthesis [18] was measured directly with respect to H2S re-moval using a fixed-bed reactor. For a first proof-of-principlewith respect to their adsorption properties, these nanoparticleswere combined with high-surface-area activated carbon. Asdescribed in literature [19–21], carbon was impregnated by adispersion of the pristine nanoparticles and the adsorptioncapacity was measured after removal of the dispersing solvent.An iron oxide/carbon nanocomposite material was synthe-

sized from an iron oxide/monomer dispersion with subsequentpolymerization and pyrolysis to facilitate a direct embedding ofthe nanoparticles into the carbon framework. These new mate-rials were tested for removal of H2S under ambient conditionsand the results were compared to materials synthesized by theimpregnation method.

2 Experimental

2.1 Materials and Reagents

Iron oxide (FexOy) nanoparticles from spray flame synthesis(details see below) served as raw material for further process-ing. A standard activated carbon, namely Carbotech C40/4supplied by Carbotech AC GmbH (Germany), was taken forimpregnation experiments with FexOy nanoparticles and forcomparison measurements. Gases for adsorption characteriza-tion were supplied by Air Liquide. Nitrogen (99.99%) was usedas purge gas; adsorption of hydrogen sulfide (99.5%) from car-rier gas methane (99.95%) was tested in fixed-bed break-through experiments. Pure hydrogen sulfide was employed fortreatment of as-prepared iron oxide nanoparticles. All gasesmentioned had the highest available grade and were appliedwithout further purification. Certified test gases were used forgas chromatograph calibration.

2.2 Characterization

The synthesized nanoparticles and subsequent products werestudied by transmission electron microscopy (TEM) on a Phil-ips CM12 TEM. An Oxford EDX system was used for energydispersive X-ray spectroscopy (EDX) measurements of the im-aged materials. An X-ray diffractometer X’pert PRO (PANalyti-cal) was employed for X-ray diffraction analysis (XRD) of pris-tine nanoparticles and of the composites as well as thematerials after adsorption of H2S. Additionally, the impregna-tion products were investigated with a LEO 1530 scanning elec-tron microscope (SEM). Infrared spectroscopy was carried outon a Bruker IFS66v/S infrared Fourier spectrometer (FT-IR).Thermogravimetric analysis (TGA) of polymeric materials wasperformed on the thermal analysis apparatus NETZSCH STA449 F3 Jupiter. In addition, certain materials were probed by

elemental analysis (EA) using atomic absorption spectroscopy(AAS), which was done according to DIN EN ISO/IEC17025:2005. The porosity was analyzed for each material bymeasuring the adsorption isotherm of nitrogen at –196 �C. Alladsorption measurements were performed using the volumet-ric sorption apparatus BELSORP-max (BEL Japan, Inc.). Priorto all porosity analyses, samples were pretreated at high tem-perature, i.e., 200 �C for at least 4 h, and low pressure at a vacu-um level below 10–3 Pa to remove pre-adsorbed humidity. Porevolume and BET surface were subsequently derived from thenitrogen isotherms according to DIN ISO 9277 [22]. Further-more, pore size distributions were calculated with the analysissoftware BELMaster under the assumptions of slit-shaped, car-bonaceous pores using the Non-Local Density FunctionalTheory (NLDFT) [23].H2S treatment and breakthrough curve measurements were

carried out in a fixed-bed adsorption system. A schematic illus-tration of the experimental setup is presented in Fig. 1.

The setup consists of a stainless-steel adsorption column,two thermal mass flow controllers (Bronkhorst Hi Tech), and am-gas chromatograph (Varian) for gas analysis. The instrumentis equipped with pressure and temperature sensors for processmonitoring. All devices are connected with stainless-steel tub-ing. The whole setup was temperature-controlled at 25 �C. Allmedium-contacted devices like column, valves, and tubing arepassivized by an amorphous silicon coating (Restek, Silco-Nert� 2000) to avoid adsorption of hydrogen sulfide on metal-lic surfaces. Data logging and processing was done withNational Instruments hardware and the software LabVIEW.For pretreatment, the adsorbent materials were heated for at

least 12 h in a drying oven, standard and nanoparticle-impreg-nated activated carbon at 200 �C and nanoparticles and com-posite materials at 300 �C. Prior to breakthrough curve meas-urements, adsorbent materials were packed into the column.Subsequently, the bed was purged with nitrogen (< 1 ppmv

H2O) at the standard adsorption temperature of 25 �C. In anext step, the bed was purged with methane for at least 10minto avoid co-adsorption of methane and traces of impuritiesduring measurement and to assure equal conditions for allexperiments. Afterwards, the column was locked up and thegas stream was passed over a bypass to adjust hydrogen sulfide

Chem. Eng. Technol. 2014, 37, No. 11, 1938–1944 ª 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim www.cet-journal.com

Figure 1. Schematic illustration of the experimental setup forH2S-treatment and measurement of breakthrough curves.

Research Article

concentration. Methane and hydrogen sulfide were mixed atthe desired ratio using two mass flow controllers to reach lowconcentrations similar to practical cases. The gas mixture wasanalyzed inline with a gas chromatograph via a connected sam-pling line. After achieving stationary conditions, valves wereswitched and the gas stream was passed through the column.All adsorption experiments were carried out at 1.3 kPa and25 �C.For breakthrough measurements of the composite material

and for the H2S treatment experiments, the adsorbent was en-capsulated between two PTFE disks with non-adsorbable wo-ven fabric to assure immobilization of the material. The PTFEdisks were adapted into the stainless-steel column.

3 Results

3.1 Nanoparticle Synthesis

Iron oxide nanoparticles were synthesized by spray flame syn-thesis from a 0.3mole solution of iron(III) acetylacetonate(Fe(III)acac) in toluene. Burner systems similar to the one usedhere are particularly designed for the formation of metal oxidenanoparticles [18]. The complete experimental setup consistsof a burner mounted in a reaction chamber, a liquid precursordelivery system, and a cooled filter apparatus for collecting theparticles; see Fig. 2. The precursor solution is injected into thereaction chamber through a hollow needle and atomized by acoaxial oxygen jet at 9 LSTPmin–1 in order to form a spray. Thespray is initially ignited by a premixed methane/oxygen pilotflame at 1.5 LSTPmin�1

CH4/3 LSTPmin�1

O2surrounding the spray.

Nanoparticle formation and growth takes place at decreasingtemperature downstream the flame [17] and is quenched by in-jecting N2 as cooling gas at 300 LSTPmin–1. The pristine par-ticles are separated from the gas stream and collected on a filtermembrane.ATEM image of the pristine iron oxide nanoparticles is pre-

sented in Fig. 3 a. The material exhibits mostly spherical,slightly agglomerated particles with a count median diameterof 7.5 ± 1.9 nm, calculated from a histogram of the TEM char-acterization.

Rietveld refinement of the XRD measurements using thesoftware MAUD [24, 25] yields a mean crystallite size of6 ± 1 nm, which is in good agreement with the TEM results.The diffraction pattern indicates that the product consists pre-dominantly of g-Fe2O3 (maghemite) and additional X-ray pho-toelectron spectroscopy (XPS) measurements are supportingthis conclusion.The FT-IR spectrum of the pristine product (see Supporting

Information) mainly shows very strong and broad absorptionbands around 3260 cm–1 and 1560 cm–1, indicating the prevail-ing presence of adsorbed H2O and OH groups on the particle’ssurface. Absorption bands in the range of 1300–1500 cm–1 areexpected to originate from adsorbed CO2 and carbonate, re-spectively [26]. The typical Fe–O vibrations between 400 and800 cm–1 are not visible due to detector limitations.To investigate whether the pristine material shows activity

towards the adsorption of H2S, the freshly prepared powderwas treated with pure H2S gas at room temperature. ThroughH2S treatment, the particles undergo a significant change inmorphology; see Fig. 3 b. Formerly separated, spherical par-ticles have built amorphous, aggregated structures togetherwith the emergence of rod-shaped crystals, which must belongto iron oxide/hydrogen sulfide reaction products [27]. EDXprobing and elemental analysis (not shown here) denote a highconcentration of sulfur in the sample indicating a chemical re-action between iron oxide and H2S [28] such as:

Fe2O3 þ 3 H2S fi Fe2S3 þ 3 H2O (1Þ

2 Fe2O3 þ H2S fi 4 FeOþH2 þ SO2 (2Þ

XRD analysis clearly indicates massive structural changesafter hydrogen sulfide admission flow compared to the as-pre-pared material (see Supporting Information). Unfortunately,identification of the resulting species was not possible due tothe high complexity of the diffraction pattern most probably


Figure 2. Scheme of the reactor setup for spray flame synthesisof iron oxide nanoparticles.

Figure 3. TEM images of (a) as-prepared iron oxide nanoparti-cles; (b) after treatment with H2S.


originating from several iron-sulfur compounds. In accordancewith the results mentioned before, the FT-IR spectrum of theH2S-treated material also exhibits a distinct change and indi-cates iron sulfide reaction products. The almost completelyoverlaid bands around 2930 and 2860 cm–1 plus the strong ab-sorption band at 1130 cm–1 and the weak ones around 890 and730 cm–1 most likely belong to iron(II) sulfide [29]. Additional-ly, the signals of the OH-groups are broadened and shiftedfrom 3260 cm–1 to 3200 cm–1, also indicating a crucial changeof the particle surface situation. These findings are similar toresults obtained by Cummins et al. [30]. They report a trans-formation of iron oxide to iron oxide/sulfide species duringsulfurization with H2S. This process occurs on the basis of fourdiffusion processes with hydrogen molecules and sulfur, oxy-gen, and iron atoms being involved, creating different iron/oxygen/sulfur species and water.

3.2 Impregnation of Hard Coal-Based ActivatedCarbon

To investigate the functionality of the pristine iron oxide nano-particles as proof of concept, the commercial Carbotech C40/4activated carbon was impregnated with the as-prepared Fe2O3

nanoparticles. A dispersion of 0.5 wt% iron oxide nanoparticlesin methanol was prepared by ultrasonic treatment and subse-quently added to the activated carbon in a mass ratio of 3.3:1and 4:1 dispersion/activated carbon, respectively. Methanol wasevaporated and the material was subsequently dried under vac-uum conditions at 50 �C, resulting in iron oxide nanoparticleimpregnated activated carbon with an iron oxide mass load of1.6 (sample I1) and 2wt% (sample I2), which was validated byelemental analysis.SEM images in Fig. 4 of the impregnated activated carbon

clearly show that the iron oxide nanoparticles are distributed assmall agglomerates both on the external carbon surface and in-side the porous structure.Gas adsorption studies were performed to investigate the po-

rous system before and after impregnation and to measure theH2S adsorption properties of the yielded products. Fig. 5 showsthe nitrogen uptake of the standard activated car-bon at –196 �C in comparison to nanoparticle-im-pregnated materials. BET surfaces and pore vol-umes are listed in Tab. 1.As expected, infiltration of nanoparticles reduced

the accessible pore volume and hence the maxi-mum nitrogen uptake. The infiltrated material lostapprox. 30% of its initial pore volume (0.73 vs.0.52 cm3g–1), whereas the inner BET surfaces ofsample I1 (1250m2g–1) and I2 (1135m2g–1) did notshow any pore blocking. Taking into account thatthe nanoparticles used for these experiments arearound 7.5 nm in size and tend to agglomerate (seeFig. 5), it can be deduced that infiltration primarilyoccurred in the mesoporous scale, leaving the mi-cropore system, and thus material’s physisorptiveproperties, nearly unchanged.

Fig. 6 displays the measured breakthrough curves for the ad-sorption of H2S onto standard activated (S) and nanoparticle-impregnated activated carbon. The low affinity of polar hydro-gen sulfide toward the nonpolar surface of activated carbon isreflected in an almost instantaneous breakthrough of the threesamples. For the standard material, an equilibration wasreached after approximately 11 000 s. In the case of impreg-nated carbons I1 and I2, no equilibration was observed withinthese experiments; nonetheless, the impregnated materials


Figure 4. SEM images of sample I2: (a) overview of particle dis-tribution on the surface of the supporting activated carbon. Thebright small areas of 100 nm in size and below indicate agglom-erates of the iron oxide nanoparticles; (b) view into a macro-pore. It is obvious that the surface of the activated carbon iscovered with iron oxide nanoparticles.

Figure 5. Adsorption isotherms of nitrogen at –196 �C on activated carbonC40/4 (S) and its nanoparticle-impregnated derivates (I1/I2).

Research Article

show different adsorption behavior. After a fast increase of theH2S concentration in the effusing stream, the breakthroughcurves exhibit a quasi-plateau with kinetically limited adsorp-tion rates, indicating the expected chemisorptive redox reactionbetween hydrogen sulfide and Fe2O3 nanoparticles. In contrastto the results reported by Cummins et al., the experimentspresented here were done under ambient temperature, thuslimiting the reaction rate [30]. Compared to the initial shortperiod of physisorptive micropore adsorption, the rate ofchemisorptive adsorbed H2S is comparably slow, most proba-bly due to room temperature measurements, a limited surfacearea, and inhomogeneous distribution of infiltrated iron oxideagglomerates. Moreover, the total amount of available activeiron oxide adsorption centers is quite low. To deal with theseproblems, a completely new route of adsorbent design wasdeveloped.

3.3 Iron Oxide/Carbon CompositeMaterial

In order to homogeneously embed the iron oxidenanoparticles within a carbonaceous host and toincrease the nanoparticle mass loading, a complete-ly new bottom-up approach was developed to syn-thesize a material enabling high accessibility of theiron oxide nanoparticles, reasonable porosity, andgood mechanical integration of the nanoparticleswithin the porous network. To this goal, pristineFe2O3 nanoparticles from spray flame synthesiswere dispersed in methanol via ultrasonication for1 h and then dropwise mixed with 4mmol decyltri-methoxysilane (DTMS) per gram particles to func-tionalize their surface area and change its proper-ties from hydrophilic to lipophilic. The solid phasewas separated from the reaction mixture by centri-fugation and washed by redispersion in methanoland centrifugation again. Finally, the surface-func-tionalized nanoparticles were dried in vacuum.

A portion of 2.5 g of the functionalized iron oxide nanoparti-cles were dispersed in 55mL styrene followed by addition of4.5mL divinylbenzene (DVB) as linker and 0.4 g azo-bis(isobu-tyronitrile) (AIBN) as initiator for the subsequent radical sus-pension polymerization. The reaction mixture was poured intonitrogen-purged, preheated deionized water at 90 �C andstirred vigorously for 3 h under nitrogen atmosphere. The re-ceived polymer nanoparticle composite beads were filtrated,washed in methanol, and dried in vacuum at 50 �C. Thermalgravimetric analysis (TGA) revealed a mass loading of 3.6 wt%iron oxide in the composite, and TEM investigations indicatedan extensive distribution of the nanoparticles in the polymer asdisplayed in Fig. 7, left image. The Fe2O3/polymer compositewas subsequently pyrolized in a programmable rotary furnace(HTM Reetz GmbH) at 400 �C for 17 h (P1) and 350 �C for25 h (P2), respectively.Due to the mild pyrolysis conditions, the morphology of the

composite material did not change significantly. However,TEM investigations in Fig. 7, right image, illustratean accumulation of nanoparticles in the outer areaof the composite material. This effect is attributedto shrinkage and material loss of the polystyrenenetwork due to thermal decomposition of polysty-rene during pyrolysis. Advantageously, this effectexposes part of the active particles at the surface ofthe composite and, therefore, makes them highlyaccessible for process gases.XRD analysis and consequent Rietveld refine-

ment showed that the treatment at 400 �C causedan increase in crystallite size of the iron oxidenanoparticles from 6 to 15 ± 1 nm (P1), whereaspyrolysis at 350 �C led to a minor crystallite growth(11 ± 1 nm, sample P2). The slight crystal growthcan be attributed to low-temperature sinteringinduced by surface effects, which is typically ob-servable for nanoscale particles [31, 32]. In addi-tion, XRD (see Supporting Information) indicateda minor formation of a-Fe, i.e., about 3% by mass


Table 1. Textural characteristics of adsorbent materials and operating condi-tions of breakthrough curve measurements.

Adsorbentsample

Description BET surface[m2g–1]

Pore volume[cm3g–1]

Sampleweight [g]

Flow rate[LSTPmin–1]

S Activated carbon(AC)

1400 0.73 11.185 4

I1 AC impregnatedwith 1.6 wt%FexOy-NP

1250 0.61 11.975 4

I2 AC impregnatedwith 2.0 wt%FexOy-NP

1135 0.52 9.260 4

P1 Compositematerial

140 0.20 0.687 3

P2 Compositematerial

150 0.30 0.797 3.5

Figure 6. Breakthrough curves for adsorption of H2S from methane on activatedcarbon and nanoparticle-impregnated activated carbon.


as obtained from Rietveld refinement, due to re-duction of iron oxide during pyrolysis.The adsorption and desorption isotherms of

nitrogen measured on these two novel compositematerials P1 and P2 are illustrated in Fig. 8. A hys-teresis between adsorption and desorption curveindicates the occurrence of capillary condensationand is typically observed for mesoporous structureswith pores between 3 and 5 nm referring to poresize distribution; see inset in Fig. 8. A classical acti-vation step based on a partial oxidation of the car-bon network with oxygen or water would decom-pose the composite almost completely due to thehigh catalytic activity of the iron oxide nanoparti-cles. This missing process step results in an under-developed micropore system leading to a materialwith a relatively small inner surface area of140m2g–1 (P1) and 150m2g–1 (P2), respectively.Fig. 9 illustrates the breakthrough curve meas-

urements for both composite materials. Comparedto the impregnated activated carbon materials, H2Sremoval efficiency is extremely increased. Espe-cially in case of the well-performing sample P2, thebreakthrough of H2S occurs not until approxi-mately 8000 s. Although equilibrium could not beobserved within the experimental time frame, theH2S loading of P2 already sums up to three timesthe amount of H2S adsorbed by sample P1 after20 000 s. This enhanced desulfurization can be at-tributed to different effects.As derived from nitrogen sorption characteriza-

tion (Fig. 8), the produced carbonaceous compositemainly consists of pores in the mesoporous scale.In combination with the well-distributed nanopar-ticles embedded throughout the mesoporous sys-tem, this material provides a favored accessibilityof H2S molecules to a great quantity of active FexOy

centers. Moreover, the lower pyrolysis temperatureof P2 resulted in the total pore volume being 50%larger than in the case of P1 (see Tab. 1), which par-tially explains both the higher H2S capacity and thelonger retention time of P2. The improvement inH2S removal efficiency of P2 in comparison to P1

is additionally favored by the smaller size of the nanoparticlesand their higher surface-to-volume ratio, thus leading to a no-ticeable increase of active iron oxide sites available for H2Schemisorption.

4 Conclusions

Iron oxide nanoparticles with an average particle size of 7.5 nmand a mean crystallite size of 6 nm were prepared in a sprayflame reactor. For application in adsorption processes, the de-sulfurization potential of the as-synthesized particles was prov-en by H2S gas treatment experiments and subsequent TEM,XRD, and FT-IR analysis. Impregnating a custom-activatedcarbon with these nanoparticles resulted in a slightly enhancedH2S removal efficiency. Although adsorption performance wasimproved, there were some drawbacks due to insufficient nano-


Figure 7. TEM image of the Fe2O3/polystyrene composite mate-rial indicating a homogeneous distribution of the nanoparticles(dark spots) within the polymer. Right: TEM image of sample P2after pyrolysis.

Figure 8. Nitrogen adsorption (––––) and desorption (– – –) isotherms at–196 �C and pore size distribution of novel composite materials.

Figure 9. Breakthrough curves for the adsorption of H2S from methane on novelcomposite materials.

Research Article

particle infiltration of the pore system. The high content of mi-cropores was not accessible for the applied particles, thus leav-ing most of the inner surface area unchanged. In addition, theinhomogeneous scattering process led to the formation ofnanoparticle agglomerations at the entrance to meso- and mac-ropores.Consequently, a novel adsorbent for desulfurization applica-

tion was prepared. In contrast to the common impregnationmethod, a carbonaceous, porous structure with embeddednanoparticles was synthesized by creating a FexOy nanoparti-cle/polystyrene composite followed by a pyrolysis step underinert conditions. Homogeneous embedding of FexOy nanopar-ticles before carbonization procedure resulted in a well-propor-tioned distribution of highly reactive iron oxide centers withinthe carbon framework. The prepared materials exhibited poresystems in the mesoporous scale and a low inner surface areain comparison to standard and impregnated activated carbons.However, these novel adsorbents provided a significantly high-er capacity for H2S adsorption at room temperature. The re-markable enhancement in terms of H2S removal efficiency is aclear indication that this class of novel composite materials ishighly promising for adsorption applications of other polarand redox reactive (gaseous) substances.

Acknowledgement

The authors gratefully thank the European Regional Develop-ment Fund (ERDF) and the Federal State of North Rhine-Westphalia within the project ZF3 (Hightech.NRW) for finan-cial support. The authors also would like to thank Dr. Deven-draprakash Gautam for performing the XRD investigationsand Jens Theis for assistance with FT-IR measurements.

The authors have declared no conflict of interest.

Symbols used

A [cm2] interfacial area available for mass transfer

References

[1] K. Liu, C. Song, V. Subramani, Hydrogen and Syngas Produc-tion and Purification Technologies, John Wiley & Sons,Hoboken, NJ 2009.

[2] C. Song, Catal. Today 2003, 86 (1–4), 211. DOI: 10.1016/S0920-5861(03)00412-7

[3] A. J. Kidnay, W. Parrish, Fundamentals of Natural Gas Pro-cessing, Mechanical Engineering, Vol. 200, CRC Press, BocaRaton, FL 2006.

[4] S. Sircar, Ind. Eng. Chem. Res. 2006, 45 (16), 5435. DOI:10.1021/ie051056a

[5] J. Fails, W. Harris, Oil Gas J. 1960, 58 (28), 86.[6] B. Steuten, C. Pasel, M. Luckas, D. Bathen, J. Chem. Eng.

Data 2013, 58 (9), 2465. DOI: 10.1021/je400298r[7] R. Maddox, Gas Conditioning and Processing, Campbell Pe-

troleum Series, Vol. 4, Norman, OK 1998.

[8] T. J. Bandosz, J. Colloid Interface Sci. 2002, 246 (1), 1. DOI:10.1006/jcis.2001.7952

[9] H.-L. Chiang, J.-H. Tsai, C.-L. Tsai, Y.-C. Hsu, Sep. Sci. Tech-nol. 2000, 35 (6), 903. DOI: 10.1081/SS-100100200

[10] D.-Y. Choi, J.-W. Lee, S.-C. Jang, B.-S. Ahn, D.-K. Choi,Adsorption 2008, 14 (4–5), 533–538. DOI: 10.1007/s10450-008-9118-9.

[11] A. Bagreev, T. J. Bandosz, Ind. Eng. Chem. Res. 2002, 41 (4),672. DOI: 10.1021/ie010599r

[12] A. Bagreev, T. J. Bandosz, Ind. Eng. Chem. Res. 2005, 44 (3),530. DOI: 10.1021/ie049277o

[13] M.-I. Baraton, Synthesis, Functionalization and SurfaceTreatment of Nanoparticles, Nanotechnology Book Series,Vol. 11, American Scientific Publ., Stevenson Ranch, CA 2003.

[14] G. Schmid, Nanoparticles: From Theory to Application, 2nded., Wiley-VCH, Weinheim 2010.

[15] C. Gellermann, T. Ballweg, H. Wolter, Chem. Ing. Tech. 2007,79 (3), 233. DOI: 10.1002/cite.200600139

[16] K. Prasad, A. K. Jha, Nat. Sci. 2009, 1 (2), 129.[17] S. Hardt, H. Grimm, I. Wlokas, H. Wiggers, M. A. Kempf,

C. Schulz, in Nanotechnology 2012: Advanced Materials,CNTs, Particles, Films and Composites (Ed: M. Laudon),CRC Press, Boca Raton, FL 2012.

[18] L. Madler, H. K. Kammler, R. Mueller, S. E. Pratsinis, J. Aero-sol Sci. 2002, 33 (2), 369. DOI: 10.1016/S0021-8502(01)00159-8

[19] S. P. Hernandez, M. Chiappero, N. Russo, D. Fino, Chem.Eng. J. 2011, 176–177, 272. DOI: 10.1016/j.cej.2011.06.085

[20] X. Wang, J. Porous Mater. 2011, 18 (5), 623–630. DOI:10.1007/s10934-010-9418-9

[21] X. Wang, T. Sun, J. Yang, L. Zhao, J. Jia, Chem. Eng. J. 2008,142 (1), 48. DOI: 10.1016/j.cej.2007.11.013

[22] ISO 9277:2010-09, Determination of the Specific Surface Areaof Solids by Gas Adsorption – BET Method, Beuth VerlagGmbH, Berlin 2010.

[23] J. P. Olivier, J. Porous Mater. 1995, 2 (1), 9–17. DOI:10.1007/BF00486565

[24] L. Lutterotti, P. Scardi, J. Appl. Crystallogr. 1990, 23 (4), 246.[25] L. Lutterotti, S. Matthies, H. R. Wenk, Proc. of the Twelfth

Int. Conf. on Textures of Materials (ICOTOM-12) 1999, 1,1599.

[26] S. Grimm, M. Schultz, S. Barth, R. Mueller, J. Mater. Sci.1997, 32 (4), 1083–1092. DOI: 10.1023/A:1018598927041

[27] M. Caban-Acevedo, D. Liang, K. S. Chew, J. P. DeGrave,N. S. Kaiser, S. Jin, ACS Nano 2013, 7 (2), 1731. DOI:10.1021/nn305833u

[28] D. Stirling, The Sulfur Problem: Cleaning up Industrial Feed-stocks, RSC Clean Technology Monographs, Royal Society ofChemistry, Cambridge 2000.

[29] IR spectrum Iron(II) sulfide, SDBSWeb: http://sdbs.riodb.aist.go.jp (National Institute of Advanced Industrial Scienceand Technology, accessed 14 December 2012)

[30] D. R. Cummins, H. B. Russell, J. B. Jasinski, M. Menon,M. K. Sunkara, Nano Lett. 2013, 13 (6), 2423. DOI: 10.1021/nl400325s

[31] H. Nalwa, Encyclopedia of Nanoscience and Nanotechnology,American Sci. Publ., Valencia, CA 2004.

[32] A. Navrotsky, C. Ma, K. Lilova, N. Birkner, Science 2010, 330(6001), 199. DOI: 10.1126/science.1195875.



iron oxide/polymer-based nanocomposite material for hydrogen sulfide adsorption applications

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