SASIKANTH S.M., GANAPATHI R.: HYDROTHERMALLY DEVELOPED TITANIUM DIOXIDE AND EUROPIUM-DOPED ... 491–496 HYDROTHERMALLY DEVELOPED TITANIUM DIOXIDE AND EUROPIUM-DOPED COMPOSITE MATERIALS FOR PHOTODEGRADATION APPLICATIONS HIDROTERMALNI RAZVOJ TITANOVEGA OKSIDA IN Z EVROPIJEM DOPIRANI KOMPOZITNI MATERIALI ZA FOTO DEGRACIJSKE APLIKACIJE Sasikanth S.M. * , Ganapathi Raman Department of physics, Noorul Islam Centre For Higher Education, Kumaracoil, Tamilnadu, India. 629180 Prejem rokopisa – received: 2024-04-09; sprejem za objavo – accepted for publication: 2024-06-24 doi:10.17222/mit.2024.1151 Metal oxide nanocomposites are a critical element in nanoscale technology. Because of their many uses, a great deal of study has involved photocatalytic materials. These photocatalytic degradation characteristics also included applications like solar-cell applications. Wastewater management was included in the photodegradation property. The following study explored the devel- opment of europium tungstate nanocomposites with titanium dioxide and how they can be used in photocatalytic applications. The synthesis was conducted using the hydrothermal method and is characterized by Fourier-transform infrared spectroscopy, X-ray diffraction spectroscopy, scanning electron microscopy, and energy-dispersive spectroscopy. Application experiments were conducted using four distinct dyes, namely methyl orange, methylene blue, congo red and methyl red. The photodegradation experiments were conducted using visible light emitted by a tungsten-filament lamp. Methylene blue and methyl orange degraded to 20 % and 35 % after 1 hour respectively. After 90 min, the degradation of methylene blue went down to 15 % and congo red degraded down to 9 %. With the experiment conducted, the sample showed that it had a relatively higher photodegradation property with the dyes used. The results show that the compound had better reaction with these dyes, with a degradation down to 10 %. Keywords: Europium, nanomaterials, organic dyes, photodegradation Kovinski oksidi so kriti~ni element v tehnologijah izdelave nanokompozitov. Zaradi pogoste uporabe fotokataliti~nih materialov so se avtorji tega ~lanka odlo~ili za {tudijo te vrste materialov, ki bi bili odporni proti fotodegradaciji oziroma odporni proti po{kodbam zaradi u~inkovanja svetlobe. Materiali za son~ne celice so naprimer zelo izpostavljeni son~ni svetlobi in je zato njihova odpornost proti fotodegradaciji zelo aktualna oziroma zahtevana. Tudi na podro~ju ~i{~enja odpadnih vod se zahteva dolo~ena odpornost uporabljenih materialov proti po{kodbam zaradi sevanja son~ne svetlobe. V tem ~lanku avtorji opisujejo razvoj nanokompozitov na osnovi volframa (W), evropija (Eu) in titanovega dioksida (TiO 2) ter ugotovljajo njihovo uporabnost za fotokataliti~ne aplikacije. Avtorji so sintezo nanokompozitov izvedli s hidrotermalnim postopkom. Izdelane kompozite so nato okarakterizirali s Fourierjevo transformacijsko infrarde~o (FTIR) spektroskopijo, rentgensko difrakcijo (XRDS) in vrsti~no elektronsko mikroskopijo z energijsko disperzijsko spektroskopijo (SEM/EDS). Aplikacijske preizkuse so avtorji izvedli s pomo~jo {tirih razli~nih barvil: metil oran`a, metilensko modre, kongo{ko rde~e in metilno rde~e. Za preizkuse fotodegradacije so uporabili vidno svetlobo, ki jo oddaja volframska `i~ka. Metilensko modro barvilo je po eni uri degradiralo 20 %, medtem ko je metiloran` degradiral 35 %-no. Po enournem obsevanju z vidno svetlobo je metilensko modra degradirala 15 %-no in kongo{ko rde~a 9 %-tno. S temi preizkusi so na vzorcih pokazali, da imajo izdelani kompoziti relativno dobro odpornost proti foto degradaciji z uporabljenimi barvili. Rezultati so pokazali, da spojina bolje reagira s temi barvili z degradacijo pod 10 %. Klju~ne besede: Evropij, nanomateriali, organske barve, fotodegradacija 1 INTRODUCTION Nanomaterials are the pillars of nanoscience and nanotechnology. Researchers have developed new nano- materials for various applications in recent years. 1 The nanomaterial’s beneficial characteristics can be used in both structural and non-structural applications. It already has a huge commercial influence, which will certainly become even larger in the future. Using nanotechnology in many places all over the world can bring about various technological benefits and improved societal benefits. Nanomaterials are made up of many types of particles such as nanorods, nanotubes, nanocomposites, and clumps. Nanocomposites are recognized as materials that transform nanosized particles into a matrix of conven- tional materials. 2 It is possible to use several materials, such as ceramics, metal and polymers, in the manufac- ture of this sort of material. A huge increase in the mate- rial’s characteristics (e.g., mechanical strength, tough- ness, electrical and thermal conductivity) can be seen by adding a few components. A nanoparticle may be very successful when working in the 0.5–5 % weight range. Nanocomposites have also found frequent application in modern technological culture in line with nanomaterials. 3 Applications of nanocomposites include batteries with an electrocatalyst, a lightweight material used in fuel con- sumption, and artificial joints that can all be made using this material’s carbon-nanotube fibres. The material is Materiali in tehnologije / Materials and technology 58 (2024) 4, 491–496 491 UDK 661.8’02:544.526.5 ISSN 1580-2949 Original scientific article/Izvirni znanstveni ~lanek MTAEC9, 58(4)491(2024) *Corresponding author's e-mail: scholar19@niuniv.co.in (Sasikanth S. M.) also used in food packaging, fuel tanks, films, and envi- ronmental protection, and it features capabilities like flame reaction and erosion and corrosion prevention. 4 This material can also be used in capacitors for computer chips, and in applications like carbon nanotube battery cathodes and nanowires that are sensitive to ions. A natu- rally occurring clay mineral called smectite is the pri- mary component of Bentonite. 5 The volcanic glass in the ash is converted to clay particles during the weathering process in seawater. Bentonite is a useful adsorbent be- cause of its wide surface area. 6 Due to its natural abun- dance and lack of toxic components, bentonite clay is an environmentally responsible choice for enhancing the performance of the nanocomposite. The utilization of bentonite-modified nanocomposites in dye-removal ap- plications has the potential to enhance the adsorption ca- pacity and photocatalytic degradation effectiveness of harmful colours from wastewater. Consequently, this will lead to a more purified discharge and a decrease in the ecological contamination. The utilization of this synergy can enhance the effectiveness of removing a wide range of organic dyes, hence lowering the environmental im- pact caused by the textile and dye-production industries. The degradation mechanism is illustrated in Figure 1. Europium is found in the monazite sand ores containing small amounts of all the rare-earth metals. 7 It is the most reactive of the rare-earth metals. Unlike most other rare-earth metals, europium can form stable compounds in the divalent state, Europous (Eu 2+ ) as well as the usual trivalent state, Europic (Eu 3+ ). 8 Due to this highly reac- tive nature, europium compounds are selected for the synthesis of composites. The nanocomposites which are prepared now can be used for wastewater treatment using visible light with the photodegradation method. 9 Metal oxide + h eh bb u 0 (1) h b u surface 0 OH OH − (2) hp b n 2absorbed HO H + H (3) e bb+ absorbed (4) h Organic oxidation products (5) OH + Organic Degradation products (6) e b 0 + Organic Reduction products (7) Electrons and +ve holes are produced in the conduc- tion and valence bands, leading to the photon irradiation, (h ·p) of metal oxide as per equation (1). The holes may respond straight with biological particles or indirectly through inorganic compounds equation (5) or form -OH radicals equation (3) that later corrode natural substances equation (6). Additionally, the electrons can respond with biological molecules, generating fewer products. The significance of the oxygen equation (7) was that it may respond with photogenerated electrons. 2 EXPERIMENTAL PART The production of the europium tungstate/titanium dioxide composite utilized sodium tungstate (Na 2 WO 6 ) as the primary ingredient. The solution consists of 0.05-M europium nitrate [Eu(NO 3 )] weighing 1.65 g, 0.243g of sodium hydroxide (NaOH), 4g of titanium IV isopropoxide purchased from Sigma-Aldrich, and 100 mL of deionized water. The hydrothermal method was employed for the preparation. 2.1 Preparation of Europium Tungstate To make the sample of europium tungstate (Eu 2 WO 6 ), begin by dissolving 1.65g of sodium tungstate in 100 mL of deionized water. Allow the mixture to stir for 30 min- utes. Following the agitation of the sample, a quantity of 0.243 g of Eu(NO 3 ) was introduced into the solution of sodium tungstate at room temperature, and the solution was continuously stirred. The stirring process was con- tinued, and the NaOH solution was gradually added drop by drop until the solution reached a pH level of 10, re- sulting in the complete precipitation of Eu 2 WO 6 . Subse- quently, filter paper was employed to refine the resultant solution. The specimen was obtained and placed in a hot-air oven following filtration, where it was maintained for a duration of 14 hours at a temperature of 110 °C. Next, the sample is subjected to calcination at a tempera- ture of 400 °C. The final powdered sample is obtained following calcination. The furnace powder sample was collected and then underwent additional characterization operations. 2.2 Preparation of Europium Tungstate/Titanium di- oxide (Eu2WO 6/TiO 2) To prepare a sample of Eu 2 WO 6 /TiO 2 , the aforemen- tioned tests are replicated and titanium IV isopropoxide is introduced during the stirring process. Following the agitation, the specimen was gathered and subsequently placed in the hot-air oven for 14 hours at a temperature of 110 °C. Next, the sample is subjected to calcination at a temperature of 400 °C. Upon completion of calcina- tion, the resulting sample is transformed into a fine pow- der. The powder sample collected from the furnace un- derwent characterization after undergoing additional procedures. SASIKANTH S.M., GANAPATHI R.: HYDROTHERMALLY DEVELOPED TITANIUM DIOXIDE AND EUROPIUM-DOPED ... 492 Materiali in tehnologije / Materials and technology 58 (2024) 4, 491–496 Figure 1: Photocatalytic degradation of the metal oxide nanomaterials with visible light 2.3 Preparation of Eu 2WO 6/TiO2/Bentonite The above experiment is repeated with the synthesis of europium tungstate/TiO 2 and bentonite is added dur- ing the stirring process, and then the procedure is con- ducted as for the previous ones 2.4 Characterization Techniques X-ray diffraction spectroscopy (XRD) experiments were conducted using the Bruker D2 Phaser instrument. XRD patterns were collected within the range of 10 to 80 degrees (2 ). BRUKER Alpha T, Germany, was used to acquire Fourier-transform spectroscopy (FTIR) spectra in the range 550–4000 cm –1 . An examination employing scanning electron microscopy (SEM) was conducted uti- lising a field-emission gun SEM (JSM-7600F, Japan) op- erating at an accelerating voltage of 10 kV . The produced nanomaterials undergo photodegradation using a visible light apparatus equipped with a tungsten-filament lamp and a cooling mechanism to maintain a constant temper- ature during the experiment. 3 RESULTS 3.1 X-ray diffraction Analysis The XRD examination was performed on the pro- duced samples, and the results are presented in Figure 2. According to the spectrum data of the sample, the dif- fraction peaks for TiO 2 are observed at specific angles: 27.32°, 36.85°, 44.36°, 54.88°, 56.85°, and 62.74°. These angles correspond to the crystallographic planes 110, 101, 210, 211, 220, and 002, respectively. These findings are consistent with the information provided in the JCPDS file number 89-8304. Based on the spectra obtained from the sample, the diffraction peaks of Eu 2 WO 6 are observed at specific 2 values: 13.84, 28.26, 33.83, and 46.84. These peaks correspond to the 100, 200, 111, and 002 planes, respectively, for the mono- clinic and hexagonal phases as documented in the JCPDS file number 33-1387. The material’s crystal prop- erty can be defined by the values K 1 =1.54060, K 2 =1.54443 and K =1.39225. The XRD patterns depict- ing the characteristics of the bentonite nanoparticles are in Figure 2. The diffraction peaks seen at angles 2 = 26.52°, 36.36°, and 50.78° correspond to the crystal planes (210), (124), and (144) of the bentonite material. The XRD patterns closely match the standard JCPDS file (card no.01-088-0891). By employing the value 2 as a reference, the particle size of the material can be deter- mined using Debye-Scherer’s equation, yielding a result of 42.85 nm. 3.2 Fourier-Transform Infrared Spectroscopy Analysis Figure 3 illustrates the relationship between the as- signed frequencies and the frequency of observation by FTIR spectroscopy. The europium tungstate sample ex- hibits absorption peaks at 3543 cm –1 and 2987 cm –1 . Typically, metal oxides have an absorption band below 1000 cm –1 , which is caused by interatomic vibrations. The determination of the sample’s most intense absorp- tion band is possible. The wave numbers 3543 cm –1 and 1579 cm –1 indicate the presence of the O-H stretching SASIKANTH S.M., GANAPATHI R.: HYDROTHERMALLY DEVELOPED TITANIUM DIOXIDE AND EUROPIUM-DOPED ... Materiali in tehnologije / Materials and technology 58 (2024) 4, 491–496 493 Figure 3: FTIR spectra of prepared samples Figure 2: XRD patterns of synthesized samples band. The presence of tungstate oxide in the europium- doped tungstate oxide nanoparticles is verified by this evidence. 10 3.3 Scanning Electron Microscopy/Energy Dispersive Spectroscopy Using a scanning electron microscope, the morpho- logical structure of the sample was examined. The mate- rial was placed on aluminium stubs inside the chamber and analysed using this equipment. The images are shown in Figure 4. The images of the surface changes in europium tungstate oxide nanocomposites were obtained using a high acceleration voltage, as shown by the results with TiO 2 compounds. The sample’s mean particle size is calculated to be 43.2 from the SEM micrograph. The chemical elements present in a sample can be identified SASIKANTH S.M., GANAPATHI R.: HYDROTHERMALLY DEVELOPED TITANIUM DIOXIDE AND EUROPIUM-DOPED ... 494 Materiali in tehnologije / Materials and technology 58 (2024) 4, 491–496 Figure 5: EDS of (A) TiO 2 , (B) Er 2 WO 6, (C) Er 2 WO 6 /TiO 2, (D) Er 2 WO 6 /TiO 2 /bentonite Figure 4: S E Mo f( A )T i O 2 , (B) Er 2 WO 6, (C) Er 2 WO 6 /TiO 2, (D) Er 2 WO 6 /TiO 2 /bentonite and their relative abundance can be estimated using en- ergy-dispersive spectroscopy (EDS), as shown in Fig- ure 5. Metal multi-layer coating thickness measurements and alloy analysis is made using EDS. 11–13 3.4 Photodegradation Studies Photodegradation experiments were conducted using visible-light exposure (tungsten-filament lamp). Here, four different dyes, specifically methyl orange, methy- lene blue, congo red, and methyl red, are utilized. The degradation of all the colours occurred both in the pres- ence and absence of the nanocomposites. Figure 6 de- picts the outcome of the four dyes prior to and following irradiation with a catalyst. The results demonstrated that the produced nanocatalyst consistently accelerates the degradation process by reducing the degradation time by half. Figure 6 displays the degradation graph of the dyes, both with and without the catalyst. The dye degra- dation % can be calculated using the formula: D CC C = − × 0 0 100 where C 0 is the initial concentration of the dye and C is the final concentration. The compounds are MB – Methylene blue, MR – methyl red, MO – methyl orange, CR – congo red, CMB – compound with methylene blue, CMO – compound with methyl orange, CMR – compound with methyl red and CCR – compound with congo red. From the graph, methylene blue and methyl orange have degraded to 20 % and 35 % after 1 hour, respectively. After 75 min, degradation of methylene blue has gone to 15 % and congo red hasdegraded down to 9 %. 14 –18 4 DISCUSSION This study investigates the synthesis and application of nanocomposites of europium tungstate and TiO 2 for photocatalytic activities. The nanocomposite was synthe- sised and characterised using X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), scan- ning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDS) techniques. The nano- composite additionally incorporated bentonite clay, which augmented the degradation % as a result of its no- table absorption ability. 19,20 5 CONCLUSIONS The success of nanotechnology strongly depends on the utilization of metal oxide nanocomposites. This pa- per focuses on the synthesis and utilization of Europium tungstate nanocomposites with TiO 2 in photocatalytic processes. The effective synthesis of the nanocomposite was confirmed through characterizations using XRD, FTIR, SEM and EDS. The addition of bentonite clay, which has a high absorption capacity, has resulted in an increase in the degradation %. The incorporation of ben- tonite clay into europium tungstate/titanium dioxide (Eu 2 (WO 4 ) 3 /TiO 2 ) nanocomposites has consequences for the enhancement of the material’s structure, catalytic characteristics, and environmental applications. Benton- ite clay, which is well-known for its large surface area and remarkable adsorptive properties, possesses the ca- pability to improve the dispersion and stability of the nanocomposite particles, which ultimately leads to the production of catalytic sites that are more uniform and effective. An increase in the photocatalytic efficacy of TiO 2 can be achieved through the enhancement of light absorption and the facilitation of charge separation. This can lead to an improvement in the breakdown of organic pollutants in water and air-purification processes. In ad- dition, the mechanical strength and thermal stability of the nanocomposite can be improved, which will result in an increase in its durability throughout the operation. Be- cause they contain bentonite, (Eu 2 (WO 4 ) 3 /TiO 2 ) nano- composites have the potential to provide an alternative to SASIKANTH S.M., GANAPATHI R.: HYDROTHERMALLY DEVELOPED TITANIUM DIOXIDE AND EUROPIUM-DOPED ... Materiali in tehnologije / Materials and technology 58 (2024) 4, 491–496 495 Figure 6: Degradation of four different dyes with and without catalyst conventional additives that is both more cost-effective and less harmful to the environment. The potential uses of these nanocomposites in areas such as waste manage- ment, environmental remediation and advanced material manufacture are expanded as a result of this. Two dis- tinct dyes were utilized in the degradation procedure. Methylene blue and methyl orange degraded to 20 % and 35 % after 1 hour respectively. 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