degradation of furfural in contaminated water by...

Scientia Iranica C (2017) 24(3), 1221{1229

Sharif University of TechnologyScientia Iranica

Transactions C: Chemistry and Chemical Engineeringwww.scientiairanica.com

Degradation of furfural in contaminated water bytitanium and iron oxide nanophotocatalysts based onthe natural zeolite (clinoptilolite)

Z. Esmaili, A.R. Solaimany Nazar� and M. Farhadian

Department of Chemical Engineering, Faculty of Engineering, University of Isfahan, Isfahan, Iran.

Received 14 June 2015; received in revised form 2 December 2016; accepted 24 April 2017

KEYWORDSAdvanced oxidationprocess;Contaminated water;Furfural;Nano photocatalyst;Titanium oxide.

Abstract. In this study, the performance of advanced oxidation process using titaniumand iron oxides based on the natural clinoptilolite zeolite (TiO2/Fe2O3/Clinoptilolite)as a nanophotocatalyst was studied, and the e�ects of various factors on the furfuraldegradation, such as pH, dosage of catalyst, initial concentration of furfural, and contacttime, were examined. The co-precipitation method was applied for the synthesis of thenanophotocatalyst. The SEM and XRD analyses showed a uniform distribution of titaniumdioxide and iron nanoparticles on the zeolite. The furfural degradation could successfullyhappen at neutral to alkaline solutions. Moreover, increasing the amount of catalyst from0.5 to 1.5 g/L does not have signi�cant e�ects on the degradation e�ciency. By enhancingthe initial concentration of furfural from 75 to 300 mg/L, the rate of degradation decreases.The maximum e�ciency of 98% could be achieved for 75 mg/L solution by using 1.5 g/Lcatalyst in pH equal to 8 within 120 minutes.© 2017 Sharif University of Technology. All rights reserved.

1. Introduction

Due to increased wastewater production and variety ofpollutants, precautionary actions are essential for theenvironment protection. One of the main sources ofwater pollution is release of chemical compounds frompetrochemical industries, oil re�neries, and chemicalplants into the environment. Most of these chemicalsare non-biodegradable and cannot be removed throughbiological systems. Nevertheless, they have toxic e�ectson living organisms, such that many aromatic andcyclic organic compounds, such as phenol and furfural,have these properties. Furfural, a toxic and hazardouschemical with adverse e�ects on living organisms, has

*. Corresponding author. Tel.: + 98 31 37934027;Fax: + 98 31 37934031E-mail addresses: [email protected] (Z. Esmaili);[email protected] (A.R. Solaimany Nazar);[email protected] (M. Farhadian)

been exceeding in the amount in industrial wastew-ater, and therefore should be speci�cally consideredin treatment processes [1-3]. Furfural is widely usedin various processes such as extraction, paper mills,and separation of colors from other hydrocarbons.Advanced oxidation processes generally include theformation and the use of strong oxidizing agents suchas hydroxyl radicals. These processes are relativelynew and have been used in puri�cation of di�erentindustrial waste waters [4]. These processes can breakdown the toxic chemicals and compounds that areresistant to biological treatment methods in the envi-ronment. Chemical oxidation processes have receivedmuch attention in recent years [1-6]. In these typesof reactions, UV (Ultra Violet) irradiation could beused solely or combined with other oxidizing agents andmineral catalysts. Some of these chemical oxidationprocesses in the degradation of furfural have beenreported as e�ective in the removal of various chemicalcomplexes [1-3,7-9].

1222 Z. Esmaili et al./Scientia Iranica, Transactions C: Chemistry and ... 24 (2017) 1221{1229

In this regard, Faramarzpour et al. used titanianano-particles for the photocatalytic degradation offurfural in a oating-bed photoreactor. Accordingto their results, a furfural concentration reductionof more than 95% was observed within 2 hours [8].Nezamzadeh and Moeinirad removed the furfural bythe NiS-clinoptilolite photocatalyst. The NiS particlesout of the zeolite framework did not show signi�cantdegradation e�ciency [9]. Ahmadi et al. used TiO2nanoparticles immobilized on a glass support, and theirresults demonstrated that the furfural photocatalyticreaction in 140 minutes led to the production of maleicand tartaric acids as intermediates [6]. Hosseini et al.immobilized TiO2 on leca (light weight expanded clayaggregate) granules for photocatalytic degradation offurfural in a batch reactor. Based on their research,the rate of furfural degradation was positively a�ectedby using UV radiation [10]. Zhang et al. synthesizedstrontium titanate microtubules and investigated theirphotocatalytic activity for degradation of furfural inaqueous solutions. As a result, they found that thephotocatalytic capacity of synthetic strontium titanatemicrotubules under the condition of calcinations tem-perature at 1000�C is the highest [11]. Mousavi-Mortazavi and Nezamzadeh used supported iron oxideonto an Iranian clinoptilolite as a heterogeneous cata-lyst for photodegradation of furfural in a wastewatersample. Their results have shown that the e�ciency ofthe process signi�cantly depends on the experimentalfactors [12]. Veisi et al. investigated photocatalyticdegradation of furfural in an aqueous solution by N-doped titanium dioxide nanoparticles. In their re-search, the e�ciency of furfural removal was foundto increase with increased reaction time, nanoparticleloading, and pH, whereas the e�ciency decreased withincreased furfural concentration [13]. Soltan et al.used nano TiO2/SiO2 deposited on cementitious ma-terials for enhancement of photocatalytic degradationof furfural and acetophenone in water media. Theresults showed that the removal of these pollutantsfrom water using mentioned photocatalyst under UVirradiation was performed with greater e�ciency, whichdoes not require an additional separation stage torecover the photocatalyst. Therefore, it would beapplicable for use in industrial wastewater treatmentat room temperature and atmospheric pressure withinthe optimized pH range [14].

These processes are perfect to be substituted with�ltering, adsorption, reverse osmosis, and other meth-ods that are conventionally applied to remove the non-biodegradable chemicals. There are various nanoparti-cle immobilization techniques for synthesis of photocat-alysts including sol-gel, co-precipitation, hydrothermal,as well as shrinking methods [1]. Impregnating ofcatalyst onto suitable supports is a strategy that hasbeen used to enhance the photodegradation e�ciency.

Among the supports, zeolites are the most famouscandidates due to their good properties such as highcation exchange capacity, high adsorption capacity, etc.High cation exchange capacity prevents aggregation ofsupported catalysts that increases e�ective surface areaof the catalyst. High adsorption capacity of supportscan be a cause for bringing molecules of pollutant nearthe catalyst, and hence photodegradation e�ciencytends to increase [15]. Due to these advantages, wehave used a cost-e�ective natural zeolite as a goodsupport in our experiment.

The main objectives of this research includestudying the e�ect of a new and e�cient synthetic ironand titanium nanophotocatalyst based on the naturaland cost-e�ective zeolite (clinoptilolite) on the degra-dation of the furfural for the �rst time and evaluationof the factors e�ect, such as the contact time, pH,the initial concentration of furfural, and the amountof catalyst on the destruction of furfural. The XRD(X-Rag Di�raction) and the SEM-EDX (ScanningElectron Microscope-Energy Dispersive Spectroscopy)analyses are employed to investigate the compositionand morphology of the photocatalysts.

2. Materials and methods

2.1. MaterialsNatural clinoptilolite was obtained from Semnan in thenortheastern region of Iran. Furfural, TiCl4, FeCl3,sodium hydroxide, sulphuric acid, hydrogen peroxide,and all other chemicals in analytical grades wereobtained from Merck, Germany. Moreover, the waterused throughout the experiments was both distilled anddeionized. The pH of the solutions was adjusted bysodium hydroxide and sulphuric acid solutions whenneeded.

2.2. Experimental setupThe photodegradation experiments were performed bya batch photocatalytic reactor system. The systemwas a cylindrical pyrex-glass cell with 250 ml capac-ity. Irradiation experiments were performed using amedium pressure Hg UV lamp 8W (6 � 212 mm, 254nm, Philips, Germany) placed in a quartz tube withone end tightly sealed by a te on stopper. The lampand the tube were immersed in the photoreactor cell.A magnetic stirrer was used continuously to guaranteesu�cient mixing of the solutions. The reaction wascarried out at room temperature. Cooling water wasintroduced to the jacket, surrounding the photoreac-tor for cooling and maintaining constant temperatureduring the experiments.

2.3. Analytical tests2.3.1. Photocatalytic testsThe furfural concentration in the samples was mea-sured by an UV spectrophotometer (Jasco, V-570,

Z. Esmaili et al./Scientia Iranica, Transactions C: Chemistry and ... 24 (2017) 1221{1229 1223

Japan). For this purpose, the samples were analyzedat maximum wavelength of 275 nm by a quartz cell(Starna, England). The Chemical Oxygen Demand(COD) measurements were carried out by a CODanalyzer of Lovibond (England) based on the standardmethods for the examination of water and sewage [16].The degradation of the furfural samples in a number ofexperiments was also monitored by high-performanceliquid chromatography (KNAUER, manager 5000, Ger-many). The XRD pattern of samples was preparedusing a Bruker di�ractometer (D8 Advance) with a Ni-�ltered copper radiation (K� = 1:5406) in 2� rangeof 6-80�. In addition, the surface morphology ofsamples was determined using a Philips XL30 ScanningElectron Microscope (SEM). The EDX analysis wasalso taken for the chemical analysis of the samples usingthe ALS2300C model, Germany. The weight percentof compounds in the samples was measured by X-RayFluorescence (XRF) analyzer (Bruker, S4PIONEER,Germany).

2.4. Preparation of zeolite sampleFor preparation of zeolite, �rst, impurities of the rawzeolite samples were separated by mechanical methodsand the zeolite was grounded by a mortar and pestle.Then, the obtained powder was screened by ASTM(American Society for Testing and Materials) standardsieves of 200 to 400 micron sizes. After removal ofthe impurities, the samples were washed by deionizedwater, and then dried in ambient temperature (25�C)to get prepared for the next steps.

2.5. Immobilization of titanium and ironoxides on the natural zeolite(clinoptilolite)

To immobilize titanium and iron oxide nanoparticleson the natural zeolite, �rst, the zeolite powder (25.4%wt/wt of the photocatalyst) was prepared by mixingit with distilled water and heating to 70�C. For thesynthesis of the nanophotocatalyst, the solutions ofTiCl4 (71% wt/wt) and FeCl3 (3.6% wt/wt) weresimultaneously added to the zeolite powder drop-wisewhile mixing together. Meanwhile, the pH of thesuspension was adjusted at 2.0 for producing a steadysolution. Then, the mixture was heated at the sametemperature for 4 hours with vigorous shaking untilthe solvent was evaporated. Afterwards, the solutionwas placed still for 12 hours until the conversion ofTiCl4 and FeCl3 into their oxides was completed. Theproducts were repeatedly washed with deionized water,and then dried in an oven at 80�C for 2 hours. Finally,the calcination process was performed in a Mu�efurnace at 400�C for 2 hours [17].

2.6. The photocatalytic activityThe degradation e�ciency was determined by obtain-ing the absorbance of the solutions before and after

Figure 1. Calibration curve of furfural.

photodegradation experiments at the wavelength ofmaximum absorption (275 nm) of furfural using aUV-Visible spectrophotometer. At this wavelength, astandard graph of absorbance versus the concentrationof furfural calibration curve was prepared that is shownin Figure 1. This graph shows a linear variation up to0.01 g/L concentration. Therefore, the samples withhigher furfural concentration were diluted with distilledwater, when needed, to lessen the concentration below0.01 g/L for accurate determination of the furfuralconcentration. Calibration equation:

absorbance = 0:141CF + 0:013; r2 = 0:991:

2.7. Experimental procedureIn each of the experiments, a certain amount ofnanophotocatalyst was added into a furfural solutionwith speci�ed concentrations. Also, for increasing theamount of radical hydroxyls and the e�ciency, 0.4 g/LH2O2 was added into the solution. Then, the preparedsolution was exposed to UV irradiation to determinethe destruction e�ciency after a speci�ed period oftime.

The Minitab software version 16 was used foroptimization of experiments due to the multiplicity ofexperiments.

2.8. Con�rmatory testsA furfural degradation measurement by applying spec-trophotometer was compared to the HPLC (High-Performance Liquid Chromatography) and the CODanalysis results on a 0.1 g/L furfural sample.

3. Results and discussion

3.1. Characterization3.1.1. Chemical composition of clinoptiloliteThe XRF results of the chemical composition of pu-ri�ed natural clinoptilolite are presented in Table 1.Si/Al ratio is 4.14 for clinoptilolite, which is within theranges reported in literature [18,19]. The agreementbetween results of previous studies and the currentobtained results proves that the applied zeolite isclinoptilolite [9,17]. The results also show that the


Table 1. The XRF results of natural clinoptilolite andthe synthesized photocatalyst.

CompoundNatural zeoliteconcentration

(%W/W)

Photocatalystconcentration

(%wt/wt)SiO2 72.13 29.83

Al2O3 10.50 4.24CaO 1.94 0.128K2O 1.77 0.549

Fe2O3 1.68 4.27Na2O 1.66 0.705MgO 0.878 0.206TiO2 0.220 53.53SrO 0.209 0.020SO3 0.140 0.11ZnO - 0.012Cl - 0.73

BaO 0.058 -MnO 0.033 -ZrO2 0.022 -CuO 0.018 0.028Rb2O 0.011 -LOI 8.55 5.597

Total 99.82 99.95

molar ratio (Fe2O3/TiO2) of 6 equaling 4% (wt/wt)of Fe2O3 in the catalyst was successfully achieved, anda novel photocatalyst was obtained.

3.1.2. XRD patternsThe XRD results of clinoptilolite and the synthesizedcatalyst show similar di�raction peaks, indicating thatthe zeolite structure did not change due to incorpo-ration of TiO2 and Fe2O3 particles. However, somedi�erences, such as broadening of the di�raction peaks,an increase or decrease in the intensity of some peaks,and the shift in the position of the peaks to slightlylower angles are observed in the spectra, particularlyin 2� range of 20-40�. The XRD pattern of thenatural zeolite demonstrates the di�raction peaks of2� = 11:35, 13.01, and 26.1, similar to those reportedin previous studies [20]. In the XRD pattern of thenanophotocatalyst, the characteristic peak of anataseTiO2 corresponding to 2� = 25:6 can be seen. Due tothe low amount of Fe in the catalyst structure, thereis no peak related to it in the XRD pattern. In fact,the intensity of the peaks in the catalyst compositedecreases with respect to that of clinoptilolite. Thisdecrease in intensity can be related to the presence orincorporation of the nanoparticles inside the structure.These changes in the relative intensities of the clinop-tilolite peaks were found in the XRD pattern after co-

Figure 2. The XRD patterns of the used clinoptiloliteand the used nanophotocatalyst.

precipitation. The XRD patterns of the used naturalclinoptilolite and photocatalyst are shown in Figure 2.The similar result was also reported by Li et al. andWang et al. [17,21].

3.1.3. SEM-EDX analysisThe surface morphology of zeolite and the synthesizedcatalyst was determined through SEM images andtheir chemical structure was determined by the EDXanalysis of the samples which are presented in Figure 3.The crystallites of the unloaded zeolite have very well-de�ned layers as in the crystals. The SEM image ofthe loaded samples shows the same crystals, indicatingthat the zeolite crystallites are not a�ected by TiO2and Fe2O3 loadings. The results of the EDX spectracon�rm the loadings of TiO2 and Fe3+ particles on thezeolite matrix. The similar results were reported byWang et al. [17].

3.2. Catalytic activityA set of experiments was carried out without UVirradiation and H2O2 addition in the presence of thecatalyst to determine its surface adsorption potential.Based on these experiments, the adsorption of furfuralby synthesized nanophotocatalyst is negligible. Thedegradation kinetics of furfural was �tted with apolynomial relation:

CF = 0:002t2 � 1:413t+ 159;

where CF represents the �nal furfural concentration attime t, r2 = 0:97.

3.2.1. Optimum conditions of the designed catalystIn this study, �rst, the optimum ratio of iron totitanium dioxide and hydrogen peroxide dosage wasfound through Taguchi design. The levels of theparameters are presented in Table 2. To �nd theoptimum ratio of Fe2O3/TiO2 in the catalyst, 0%,3%, 6%, 7%, and 100% ratios of Fe2O3/TiO2 in thepresence of zeolite were prepared in which 0% is pureTiO2 and 100% is pure Fe2O3 on the clinoptilolite.Likewise, to �nd the optimum amount of hydrogen


Figure 3. The SEM images and the EDX spectra of (a) the zeolite and (b) the catalyst.

Table 2. The levels of the catalyst type and the amountof H2O2.

Type of thecatalyst

Amount of theH2O2 (g/L)

TiO2 03% 0.0756% 0.157% 0.3

Fe2O3 0.4

peroxide, di�erent concentrations of 0, 0.1, 0.2, 0.3, and0.4 g/L for H2O2 were tested. Moreover, to examinehigher hydrogen peroxide dosages, the concentrationsof 0.4, 0.55, and 0.7 g/L were also tested. In allexperiments, the test time was �xed at 2 hours basedon previous studies [1,9], and the initial concentrationof furfural was 0.3 g/L. The degradation e�ciencycurves of furfural solution with catalysts in di�erentdosages of Fe2O3/TiO2 are shown in Figure 4. Itcan be observed that by utilizing TiO2 as a catalystin the absence of iron ions, minimum value of thedestruction e�ciency is achieved. With increasingthe iron ion/titanium dioxide ratio, the destructione�ciency of furfural increases. In the molar ratioof 6%, the highest e�ciency is achieved. Then, thee�ciency decreases as the iron concentration increasesto 7 mol%. When the catalyst is formed of pureiron oxide and clinoptilolite, the degradation is moree�cient compared to the molar ratio of 3%. This

Figure 4. Degradation e�ciency of furfural catalyzed byphotocatalysts doped with di�erent dosage of iron ions indi�erent H2O2 concentrations. Time: 2 hours, the initialconcentration of furfural: 0.3 g/L.

result is similar to that of a previous study reportedby Wang et al. [17], which indicates that the photocat-alytic activities of Fe2O3/TiO2/zeolite photocatalystsstrongly depend on the concentration of iron ions. Itwas observed that the hybridized catalysts were moree�ective than pure iron and titanium catalysts. Itwas due to combination of two semiconductors thatcreates a new energy gap laid between the band gapenergies of single semiconductors [22]. The e�ect ofhydrogen peroxide on furfural degradation e�ciencyis shown in Figure 5. With increasing H2O2 dosage,from 0 to 0.4 g/L, the e�ciency increases. For the


Figure 5. E�ects of hydrogen peroxide concentration onthe furfural degradation e�ciency.

Figure 6. Main e�ects of plot for e�ciency%.

higher H2O2 dosages, another Taguchi design wasutilized. By increasing H2O2 dosage from 0.4 to 0.55g/L, the e�ciency decreases, then increases within0.55 to 0.7 g/L, and this trend is shown in Figure 5.The main e�ects of the plot of this design are shownin Figure 6. According to this plot, the e�ciencyincreases by increasing time and decreasing the furfuralconcentration.

In the second design, we used Taguchi methodagain in which initial pH value of furfural solution,concentration of furfural, dosage of the photocatalyst,and irradiation time were considered as the e�ectiveparameters; other factors, such as temperature, lightintensity, and H2O2 content, were kept constant. Thefour factors in three di�erent levels within the opti-mum operating condition (6% catalyst and 400 mg/Lhydrogen peroxide) were studied. The levels of theparameters are presented in Table 3.

Table 3. Factors and selected levels.

pHContact

time(min)

Concentration offurfural(mg/L)

Dosage ofcatalyst(g/L)

2 30 75 0/57 60 150 110 120 300 1/5

Figure 7. The contour plot of e�ciency for furfuralconcentration versus time.

3.2.2. E�ect of the furfural initial concentrationFor examination of the furfural initial concentration,the experiments were conducted in three levels offurfural concentrations: 75, 150, and 300 mg/L. Thecontour plot of e�ciency versus the furfural concen-tration and time is shown in Figure 7. It can beobserved that the degradation e�ciency of furfuraldecreases by increasing the initial concentration tovalues above 300 mg/L. By increasing the furfuralcontent, more furfural molecules are adsorbed ontothe surface of the nanophotocatalyst, and the activesites of the catalyst are reduced. Therefore, byenhancement of the occupied spaces on the catalystsurface, the generation of hydroxyl radicals decreases.Also, increasing the concentration of furfural can leadto decreasing the number of photons that reaches thesurface of the nanophotocatalyst. Therefore, the UVlight is absorbed by the molecules of furfural, and thestimulation of nanophotocatalyst particles by photonsis reduced. These results are in accordance with thoseof previous studies [9,23].

3.2.3. E�ect of the contact timeTo study the e�ect of contact time, the experimentswere performed in 0.5, 1, and 2 hour periods. Figure 8illustrates that by increasing the contact time, the

Figure 8. Contour plot of e�ciency for furfuralconcentration versus pH.


e�ciency increases due to the free radical moleculesof furfural and have more opportunities to attack anddestroy the furfural molecules. The e�ciency of above98% was achieved at contact time of about 2 hours.These results are in accordance with those of previousstudies [2,3,8,9].

3.2.4. E�ect of the pHAdditional experiments were performed to determinethe most e�ective initial pH for furfural degradation.The e�ect of solution pH (in the ranges of 2-10) on thedegradation e�ciency of furfural was investigated. Thefurfural solutions were adjusted to reach the desired pHby addition of sulphuric acid and/or sodium hydroxide.As shown in Figure 8, the degradation e�ciency offurfural is higher in pH ranges of 7 to 10.

In the initial acidic pHs, high amount of conju-gated base was added to the solution. The sulfateanion, SO2�

4 , reacts with hydroxyl radicals leadingto the formation of inorganic radical ions. Theseinorganic radical anions show much lower reactivitythan hydroxyl radical and do not take part in thefurfural degradation. There is also a drastic com-petition between furfural and anions with respect toOH�. Hence, an increase in pH leads to an increase inthe degradation e�ciency. As the results show, thereis a decrease in the removal e�ciency at pH valueshigher than 7. Researchers suggested that at highconcentrations of OH� (pH above 9), two reactionsmay take place leading to the deactivation of hydroxylradical [9,24]. First, H2O2. and HO2. radicals formdue to the reaction of hydroxyl radical with OH�. Thereactivity of these radicals with organic materials is lessthan OH� [25]. Second, due to the presence of highamounts of OH� radicals, the radical-radical reactionstake place at higher pH values [26]. The deactivationof OH� radicals in high pH values has been previouslyreported [25]. Also, at neutral pH, the adsorptionof furfural is favored on nano-particle's surface, andthe degradation is increased. The same results werereported by Houas et al. and Ahmadi et al. [6,27].However, in this study, the pH changes did not havesigni�cant e�ect on the e�ciency. Moreover, due toH+ cation production, the �nal solution was acidic inall the experiments.

3.2.5. E�ect of the catalyst dosageThe initial e�ciency of photocatalytic degradation ofmany pollutants is a function of the photocatalystdosage [28]. The e�ect of photocatalyst amount onthe degradation of furfural was studied in a series ofexperiments, and the result of degradation e�cienciesversus catalyst dosages was presented in Figure 9. It isobserved that the amount of catalyst has insigni�cante�ect on the degradation e�ciency of furfural.

3.3. The results of con�rmatory tests3.3.1. The result of HPLC analysisTo evaluate the extent of degradation and mineral-ization of furfural, a HPLC analyzer was used. Forfurfural analysis by HPLC analyzer, �rst, a calibrationcurve was prepared which is shown in Figure 10. Theresults of this analysis are shown in Table 4. Theseresults con�rm those for furfural degradation duringthe photocatalytic oxidation reactions, measured byspectrophotometric technique.

3.3.2. The result of COD analyzerTo investigate the toxicity of the photocatalyzed solu-tion, the COD analysis of furfural before and after thereaction was determined, which is shown in Table 4. Asigni�cant decrease in the solution COD to above 55%

Figure 9. E�ect of catalyst dosage on the degradatione�ciency.

Figure 10. Calibration curve of furfural achieved byHPLC analyzer.

Table 4. Concentration of furfural before and afterphtocatalytic reaction.

Type of device

Concentrationof furfural

before reaction(mg/L)

Concentrationof furfural

after reaction(mg/L)

Spectrophotometer 100 4HPLC 100 5.5COD 108 48


is observed. These results con�rm the spectrophotome-ter analysis.

4. Conclusions

According to our research, photocatalytic degradationis an inexpensive, easy to run, e�ective and fast processby which the removal e�ciencies more than 95% couldbe achieved in only 120 minutes. Furfural can be moree�ciently degraded by TiO2 and Fe2O3 incorporatedclinoptilolite zeolite in the presence of UV radiation.The slurry photoreactor used in this work appeared tobe a proper system due to its capability of e�cientlydistributing catalyst through the contaminated water.An important advantage of this method is using a verysmall amount of photocatalyst (0.5 g/L). It reducesthe consumption of photocatalyst and photons dueto the reduction of scattering and �nally lessens thecontamination of the environment. Besides, maximumphotodegradation e�ciency was obtained when theexperiments were performed in the neutral to alkalinesolutions. Furthermore, the experiments were moree�cient in the low initial concentrations of furfural.The e�ectiveness of these processes was indicated bycon�rmatory tests to evaluate the removal of furfural.The XRD and SEM analysis on the photpcatalystrevealed that the method adopted to immobilize ti-tanium dioxide and iron nano-particles on the zeolitewas suitable for this purpose. No serious structuralchanges were detected in the titanium dioxide and ironparticles, and the distribution of these nanoparticles onthe zeolite surface was uniform.

Acknowledgements

The authors would like to express their thanks tothe laboratory sta� of the Department of ChemicalEngineering and Islamic Azad University of Shahreza,for their collaboration.

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Biographies

Zakie Esmaili received the BSc degree in ChemicalEngineering from Bahonar University of Kerman, theMSc degree in Chemical Engineering from IsfahanUniversity, and she is now PhD student in ChemicalEngineering at Isfahan University of Technology.

Ali Reza Solaimany Nazar is currently AssociateProfessor in the Chemical Engineering Department atUniversity of Isfahan, Iran. His research interests aremainly asphaltene and wax deposition in reservoir andtransportation line, adsorption and advanced oxidationprocess in water and wastewater treatment.

Mehrdad Farhadian is the Head of EnvironmentalResearch Institute at University of Isfahan, Isfahan,Iran. His main research interests include water andwastewater treatment and environmental engineeringin the �eld of chemical engineering.

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