Mixture Of Anatase Research Articles

Influence of Er and Yb on photoelectrochemical performance of TiO2 thin film

The strategy of modifying the titanium dioxide photoanode with an internal upconverter containing Er activator and Yb sensitizer was proposed. To assess the impact of rare earth ions, thin film TiO2, TiO2:Er, and TiO2:Er,Yb were deposited in the magnetron sputtering process on conducting glass, amorphous silica a-SiO2, and silicon. Two strategies were tested: introduction of high activator content and incorporation of low activator content with addition of sensitizer. Pure TiO2 served as a reference material. All deposited films displayed promising optical properties, such as high transparency and low reflectance in weak absorption region, and strong absorption above the fundamental absorption edge, as investigated by spectrophotometric measurements. Structural characterization by means of grazing incidence X-ray diffraction and transmission electron microscopy revealed that films crystallized as a mixture of anatase and rutile, while high concentration of modifying ions led to amorphization. Changes in surface morphology accompanied the structural transition, as shown in scanning electron microscopy analysis. Current-voltage and time-dependent measurements in photoelectrochemical cells, under white light illumination before and after cut-off of ultraviolet light, confirmed enhanced performance of TiO2:Er,Yb (1 at.%, 1 at.%) photoanodes over pure TiO2 as well as TiO2:Er (10 at.%) and TiO2:Er,Yb (2 at.%, 10 at.%).

Evolution of surface properties of titanium oxide thin films

Titanium oxide thin films were deposited by rf magnetron sputtering of Ti metallic target in flow-controlled O2 + Ar atmosphere. Comprehensive investigations of crystallographic structure, phase composition, morphology and optical properties were performed by means of X-ray diffraction, X-ray reflectivity (XRR), scanning electron microscopy, optical spectrophotometry, and X-ray photoemission spectroscopy. It was found that as the O2/(O2 + Ar) flow ratio increased, the microstructure of thin films changed from TiO, Ti2O3, to rutile TiO2, rutile-anatase mixture and, finally, to pure anatase. Special emphasis was given to soft X-ray absorption spectroscopy in surface-sensitive total electron yield mode, which provided simultaneous information on electronic occupancy and local atomic structure. Studies of titanium L23 edge revealed systematic changes in crystal field strength, increasing upon rutile formation and decreasing when anatase became the dominant phase in sputtered films. Diffuse reflectance and XRR were employed to investigate the light scattering effects related to the surface roughness. The highest value (5.3 nm) of XRR roughness was observed for pure rutile sample. Performance of films as photoanodes in photoelectrochemical cells was assessed by photocurrent vs potential and time measurements. Results revealed that crystallized, stoichiometric films containing a mixture of anatase and rutile were promising photoanode materials for green hydrogen generation.

The effect of surface modification with Ag nanoparticles on 21 nm TiO2: anatase/rutile material for application in photocatalysis

The purpose of this article is to present a perspective, environmentally friendly, and cost-effective chemical approach for preparing photocatalysts that can be used in wastewater treatment. One nanometer-sized Ag nanoparticles (NPs) were deposited on the surface of a commercial titanium dioxide mixture of anatase and rutile. A novel low-temperature chemical method using an ultrasonication process without a reducing agent was applied to surface-modified TiO2 grains with Ag NPs. The materials were characterized by several complementary techniques, such as X-ray powder diffraction (XRD), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), UV–Vis diffuse reflectance (DRS), Raman spectroscopy, X-ray electron spectroscopy (XPS), Mott-Schottky analysis, and N2 adsorption-desorption measurements. The silver content in the prepared samples ranged from 0.1 to 0.5 wt% (low Ag content) and from 1 to 5 wt% (high Ag content). The photocatalytic performance of the pristine and Ag NPs modified TiO2 powders in photodegradation of the acid orange 7 model dye was studied under ultraviolet (UV), visible (Vis) and UV + Vis radiation. This study explores, for the first time, a photodegradation mechanism for all combinations of wavelengths and silver contents, which is of practical importance in selecting the best photocatalyst and irradiation conditions.

Photodegradation of sunset yellow by TiO2/SnO2 nanocomposites films deposited using spray pyrolysis

The main objective of the work in hand is to investigate the degradation of sunset yellow dye under UV light using the TiO2 and SnO2 as photocatalysts. Thin films of TiO2 (T), SnO2 (S) and their nanocomposite (TS) were eposited by spray pyrolysis on glass substrate at 550 °C. According to X-ray diffraction (XRD), all the films had a polycrystalline structure. The S film had traces of SnO and the T film was a mixture of anatase and rutile. The TS film was a combination of anatase, rutile and SnO2. The grain size decreased from 115 nm in S to 21.5 and 18.8 nm in T and TS films respectively. Tensile strain was present in all films. The UV-Vis spectra revealed relatively higher transmittance in TS and T and lesser in S. Using the Tauc plot, the optical gap energy was calculated to be 3.60, 3.17 and 3.71 eV for S, T and TS respectively. The surface morphology examined by SEM showed homogenous grain with different shapes and sizes. The photodegradation of sunset yellow dye after 18 hours was ameliorated in the TS film to reach 90.27% where the S and T films had 19.74 and 29.65 degradation percentage respectively. The photocatalysis kinetics was found to fit a first order chemical reaction.

High-temperature solid-state rutile-to-anatase phase transformation in TiO2

TiO2 has many polymorphs, among which rutile is the most thermodynamically stable. Bulk anatase TiO2 is usually a metastable phase at room temperature. Hence, phase transformation of bulk rutile TiO2 to anatase TiO2 by heat treatment is thermodynamically forbidden. However, the stability of TiO2 polymorphs is dependent on particle size and doping level. In this work, we harnessed this characteristic to develop a solid-state high-temperature route of sequential NH3 and O2 treatment that transforms rutile TiO2 to anatase phase via grain fracture and N-doping. As an additional advantage, this technique produces a mixture of anatase and rutile phases, with anatase being a major phase. Biphasic TiO2 is advantageous from a charge separation perspective for photocatalytic applications. Furthermore, the bandgap of anatase TiO2 can be manipulated by controlling the O2 treatment time to tune it for specific applications.

Selective adsorption of epigallocatechin gallate onto highly reusable gallium doped mesoporous TiO2 nanoparticles adsorbent

This work describes a potential selective adsorption of epigallocatechin gallate by Ga-doped TiO2 nanoparticles (NPs) and showed excellent adsorption (∼99%) and desorption capacity even after the 7th run. The work reports about a surfactant mediated template based synthesis of both pristine and Ga-doped TiO2 mesoporous NPs to study the adsorption behavior EGCG. EGCG is the most abundant and bio-active compound capable of showing free radical scavenging activity, anticancer, antibacterial, and several other physiological functions. Therefore, extraction of EGCG is highly desirable for incorporation in food items that can effectively increase their nutritional and medicinal values. The pore diameter of the synthesized materials was found to be in the range 8.76–10.38 nm and the specific surface area was found to be around 25.80–58.72 m2/g. The particle size decreased from 25 nm to 15 nm in presence of Ga. A mixture of anatase and brookite phase was observed for all the synthesized TiO2 NPs. The band gap value initially (3.40 eV) decreased in presence of minute amounts of Ga (3.44 eV) but then increased (3.59 eV) with the increase of Ga percentage. The point of zero charge (PZC) value of the materials lies in the range of 6.6–7.2. The adsorption study was carried out at different pH (1, 3, 5, 7 and 9) with variation of shaking time (1 h, 3 h, 5 h and 7 h). The material containing maximum Ga in the Ga-doped set (Set 3 TiO2 NPs) showed highest adsorption percentage (99.45%) in pH 1 medium after 5 h shaking. The adsorption isotherm and the kinetics follow the Langmuir model and pseudo-second order respectively. Desorption was studied under high energy gamma rays, shaking, sonication and UV irradiation. The highest desorption (∼96%) was obtained with sonication for 30 min.

Anodic growth and pre-calcification on β-Ti-40Nb alloy: Effects on elastic modulus, electrochemical properties, and bioactivity

This study evaluated the surface optimization of β-Ti-40Nb alloy in terms of corrosion and bioactivity properties. Electrochemical anodization at different voltages was used to synthesize (Ti,Nb)O2 nanostructures (nanopores (NPs)) and (nanotubes (NTs)) on samples' surfaces, allowing the analysis of their influence on performances related to those properties. Then, (Ti,Nb)O2 NPs and NTs were annealed at 550 °C to crystallize the previously obtained amorphous (Ti,Nb)O2 into a mixture of anatase and rutile. Also, a pre-calcification process (PC) was applied on annealed (Ti,Nb)O2 NPs and NTs. SEM micrographs showed the presence of NTs (10 V) and NPs (20 V) after anodization. After annealing, the morphology of (Ti,Nb)O2 NPs and NTs remained constant for both diameter and length. XRD analysis confirmed that as-anodized amorphous (Ti,Nb)O2 was crystallized, after annealing, into a mixture of anatase-rutile phases. Corrosion properties were evaluated through the open circuit potential (OCP), potentiodynamic polarization curves, and electrochemical impedance spectroscopy (EIS). Samples were immersed in a simulated body fluid (SBF) solution for one to 14 days to assess the bioactivity. The bioactivity evaluation was carried out by mass gain. Also, the amount of apatite precipitated on the sample's surface was determined through SEM-EDS. The results showed that PC samples presented similar corrosion properties compared to the annealed samples. However, PC processing improved the bioactivity (apatite formation) of (Ti,Nb)O2 NTs and NPs modified β-Ti-40Nb alloy.

Investigation on the performance of nanostructure TiO2 bi-layer as photoanode for dye sensitized solar cell application

The photoanodes in dye-sensitized solar cells with two different morphologies such as one dimensional hydrothermally synthesized rutile nanorods and nanoparticles of TiO2 were utilized for improving the short circuit current density of the device. The synergistic effect of both the structures offer high Jsc by providing better pathway for the electron transportation through one dimensional nanorod morphology and efficient light absorption due to more dye adsorption on the mesoporous nanoparticles.With this, the condensation reaction mechanism for the formation of TiO2 rutile nanorod structure is elucidated along with FESEM analysis. The Field Emission Scanning Electron Microscope images confer the presence of highly oriented and vertically aligned nanorods. X-Ray Diffraction and RAMAN Spectroscopic studies confirm the crystalline nature of synthesized bi-layer film and it was observed to be a mixture of anatase and rutile phase of TiO2. The absorption and emission properties for the synthesized samples were studied using UV–Vis and Photoluminescence spectroscopy. The efficiency of the solar cells with the photo anodes of Nanorods, Nanoparticles and Nanorods/Nanoparticles bi-layer were found to be 0.30%, 4.41% and 4.23% respectively. Electrochemical Impedance Spectroscopic studies have done to check the charge transfer properties of the fabricated devices.

Self-organized TiO2 nanotubes on Ti-Nb-Fe alloys for biomedical applications: Synthesis and characterization

Titanium-based biomaterials with a self-organized titanium oxide (TiO2) surface have received considerable attention in recent years owing to enhanced cellular response and bactericidal behavior promoted by the nanostructured surface. The aim of this study was to investigate the effect of Fe addition on the formation and crystallization of TiO2 nanotubes on Ti-30Nb-xFe substrates and the effect of TiO2 crystallinity on biological behavior. Self-ordered TiO2 nanotubes were prepared by anodization of Ti-30Nb-xFe (x = 0, 3, and 5 wt%) alloys using an aqueous 0.3% HF (vol.%) electrolyte. The nanotube morphology, structure, and composition as a function of the annealing temperature were characterized using FE-SEM, XRD and XPS. The crystallization of nanotubes to the rutile phase occurred at similar temperatures for samples with or without Fe addition, and a mixture of anatase and rutile was observed at 675 °C. The cell viability profile on different surfaces was investigated by MTT and adhesion assays, which revealed improved in vitro response to the crystalline nanotubes.

Preparation and characterization of palladium-doped titanium dioxide for solar cell applications

The syntheses of TiO2 and Pd/TiO2 nanoparticles were carried by hydrolysis of alkoxide precursors using the reverse micelles method using titanium tetrabutoxide and palladium acetylacetonate as precursor metals. The method was modified by precipitation with the addition of n-butanol and then washed with an ethanol/water solution at a ratio of 1:1. Morphological characterization was performed by scanning electron microscopy and structural by X-ray diffraction and spectroscopy of Raman scattering. Electrical characterization was performed by impedance spectroscopy and the optical energy gap was determined from transmittance measurements Tauc plot fittings. The material was characterized by a suspension of spherical nanoparticles on the order of 100 nm confirmed by Scanning electron microscopy analysis. They also presented good ionic conductivity as indicated by impedance spectroscopy. Raman spectroscopy showed a systematic frequency shift to the left together with peak broadening as the amount of palladium incorporated onto TiO2 increases, which is characteristic of mesoscopic grains. X-ray diffractograms were carried with washed and dried powder samples and showed a mixture of anatase and brookite phases, with anatase as the predominant one.

Cork derived TiO2 biomorphic ecoceramics

Environmentally conscious biomorphic ceramics (Ecoceramics) are a new class of material manufactured from renewable resources and wastes. Sustainable cork wastes were pyrolysed, and this activated carbon template infiltrated with a sol-gel precursor (from aqueous green-chemistry) to form TiO2 on heating in air, with the honeycomb microstructure of cork. Physical and optical band gap properties were characterised by XRD, SEM and Raman and UV–vis spectroscopy, and differences between alkaline and acidic activation of the carbon template also studied. With activation by HCl, HNO3 or H2SO4, a mixture of anatase and rutile formed. NaOH activation resulted in pure anatase, but a large amount of Na was retained. At 1000 °C acid activated ecoceramics formed pure rutile, but the NaOH activated one formed Na2Ti6O13 (sodium hexatitanate) as the major phase, coexisting with anatase, brookite and rutile. This material is worth further investigation, as Na2Ti6O13 is reported as a photocatalyst in its own right.

The effect of pH on the physical and structural properties of TiO2 nanoparticles

The present study prepared TiO2 nanoparticles using the sol–gel method with solutions of various pH values (1.5, 4.5, 7.5 and 10.5). The structural, morphological and optical properties of the prepared TiO2 nanoparticles were analyzed. A mixture of anatase–rutile phase was obtained with nanoparticles prepared in an acidic medium such as pH = 1.5 and 4.5. A pure anatase phase was obtained with nanoparticles prepared in an alkaline medium such as pH = 7.5 and 10.5. The average crystallite size was calculated for the prepared nanoparticles. The crystallite sizes decreased with increased pH values. The band gaps of the prepared nanoparticles were calculated. The band gap value of the sample with a limit pH value of 4.5 for anatase–rutile phase transformation was calculated to be 3.89 eV for direct transitions and 3.68 eV for indirect transitions.

Characterization of thermal and anodic oxide layers on β- and on near-β-titanium alloys for biomedical application

Abstract β- and near-β-Ti alloys for biomedical applications show a favourable mix of mechanical, biological and biocompatible properties. In this study, oxide layers on Ti13Nb13Zr, Ti15Mo5Zr3Al, Ti30Nb and Ti30Ta were prepared by thermal and anodic oxidation, in order to adjust constant, reproducible and well-defined surface properties. The thickness, the phase composition and the element composition of the oxide layers were determined. The corrosion properties were investigated by current density –potential curves under physiological conditions. Depending on the oxidation parameters, film thicknesses in the range 10 – 250 nm can be prepared. The thermal oxide layers consist predominantly of TiO2 in rutile structure while the anodized samples show a mixture of anatase and amorphous TiO2. In addition, certain amounts of mixed oxides of titanium and alloying elements such as TiZrO4 or TiNb2O7 are found in the oxide films. The corrosion resistance of the oxidized samples is increased as compared with the polished samples whose current densities in the range of passivity are comparable to that of Ti6Al4V.

The response of bioactive titanium surfaces with different structure to UVC-irradiation to eliminate the negative effect on biological properties during aging time

The biological aging of titanium implants affects the service lifetime negatively in clinical applications, and Ultraviolet (UV) irradiation is an applicable method to overcome the biological aging. This study investigated the changes in surface characteristics and biological properties of bioactive titanium surfaces with different structure and topography after Ultraviolet C (UVC) irradiation. The bioactive titanium surfaces were prepared by anodizing (AO), sandblasting and acid-etching (SLA), acid-alkali etching (AA), alkali-heat etching (AH) methods. Samples were stored at dark for 7 weeks to simulate biological aging process and then irradiated by UVC for 2 h. The results showed that the hydroxyl groups (Ti-OH) on surfaces, which are crucial to enhance the biological properties, were easier to be generated on AO surfaces by UVC-irradiation, owing to a mixture of anatase and rutile on surfaces. UVC-irradiation had the strongest effect on AO surfaces to enhance the bioactivity in bone-like apatite deposition and better biocompatibility in mesenchymal stem cells (MSCs) attachment and proliferation. Therefore, titanium surfaces with a mixture phase of anatase and rutile have the potential to effectively utilize the benefits of UVC-irradiation to overcome the negative effects of the biological aging and have a promising clinical application prospect.

Structure and photocatalytic activity of maleic anhydride-functionalized TiO2 nanoparticles by a simple method

Titanium dioxide (TiO2) nanoparticles were functionalized with maleic anhydride (MA). The extension of adsorbed MA on the TiO2 was evaluated by ultrasonic and magnetic stirring. Total Organic Carbon and Thermogravimetric Analysis confirmed the presence of surface MA even after the washing process. The Fourier Transform Infrared and UV-Vis Diffuse Reflectance spectra clearly showed the chemical anchored maleic anhydride on the TiO2 surface as bidentate bridging adsorption. The surface modification of TiO2 extended its light absorption range to the visible light region reducing its bandgap energy from 3.05 to 2.55 eV. X-Ray Diffraction patterns showed that the TiO2 functionalized presented a mixture of anatase and rutile phases without any crystalline phase transformation after MA chemisorption process. The functionalization percentage and the reaction efficiency for the TiO2 with 5 wt% MA sample were 3.6 and 69%, respectively, as shown by Differential Thermal Analysis and Thermogravimetric Analysis. The performance of pure and functionalized TiO2 samples were evaluated in the photocatalytic degradation of the Methyl Orange dye under ultraviolet light. TiO2 with 5 wt% MA produced a maximum degradation of 97% after 90 min, 3% higher than the commercial TiO2.

Enhanced visible light photoelectrochemical water splitting using nanotubular FeOx-TiO2 annealed at different temperatures

Nanostructured semiconductor photoelectrodes that can operate under renewable solar energy are of great interest for both fundamental studies and practical applications. In this paper, we studied the semiconducting and photoelectrochemical properties of nanotubular FeO x -TiO 2 annealed at different temperatures. Nanostructured anodic titanium oxide layers were modified by impregnation with a solution containing 100 mM FeCl 3 followed by their annealing at 400 °C, 500 °C, and 600 °C. The synthesized materials were characterized by using a field emission scanning electron microscopy (FE-SEM), energy dispersive spectroscopy (EDS), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy (RS), diffuse reflectance spectroscopy (DRS), electrochemical impedance spectroscopy (EIS), Mott-Schottky analysis, and photoelectrochemical measurements. It was found that depending on the annealing temperature, the studied materials showed a different photoelectrochemical response. The lowest value of band gap was observed for the sample annealed at 500 °C, which is related to the presence of a mixture of anatase and rutile phases together with iron oxides. • Three types of morphology were detected in the studied materials. • α-FeOOH, α-Fe 2 O 3 , γ-Fe 2 O 3 , Fe 3 O 4 and FeO were detected by Raman analyses. • The narrowest optical gap was observed for the FeO x -TiO 2 sample annealed at 500 °C. • Grain boundary passivation mechanism induced by introducing FeO x was observed.

The influence of nitrogen partial pressure on visible-light-driven photocatalytic activity of sputtered titanium oxynitride thin films

Using a reactive direct current magnetron sputtering method in an Ar, O2 and N2 atmosphere, titanium oxynitride (TiOxNy) thin films were deposited on silicon and glass substrates and then annealed in air at 500 °C for 1 h. X-ray diffraction analysis indicated that the thin films displayed only a rutile titanium dioxide (TiO2) phase when oxygen was used as the reactive gas. When the nitrogen was injected into the sputtering chamber, the thin films displayed a mixture of anatase and rutile phases of TiO2. The surface morphology, characterized by a field-emission scanning electron microscope, showed growth of grain size and formation of nano-pores with increased nitrogen partial pressure. The optical bandgaps of the thin films, evaluated from Tauc plots, were in a range from 2.90 to 3.17 eV. The photocatalytic activity of the thin films was examined under visible light using methylene blue (MB) as a dye model. The experimental results indicated that nitrogen content affected photocatalytic effectiveness during MB degradation. After irradiation with white light from an LED lamp for 120 min, the highest value of the pseudo-first-order reaction rate constant was 8.93 × 10−3 min−1, obtained from the TiOxNy thin film that contained the highest nitrogen content of 3.90 at.%.

Osteoblast-like Cell Proliferation, ALP Activity and Photocatalytic Activity on Sintered Anatase and Rutile Titanium Dioxide.

This study aimed to create a biomaterial from titanium dioxide (TiO2), which has been known to have photocatalytic and bone formation promoting effects. I expected that anatase titanium dioxide-based implants could promote bone augmentation and induce bone formation. Powdery anatase TiO2 was compression molded and sintered at 700, 800, 900, and 1000 °C to prepare sintered compact samples. X-ray diffraction and scanning electron microscopy were used to observe the surface of these samples. Furthermore, mouse osteoblast-like cells (MC3T3-E1 cell line) were seeded on the samples sintered at different temperatures, and cell proliferation was observed to evaluate the cell proliferation of the samples. The sample sintered at 700 °C was composed of anatase TiO2. The samples sintered at 800 °C and 900 °C were confirmed to consist of a mixture of anatase and rutile TiO2 crystalline phases. Moreover, the sample sintered at 700 and 800 °C, which contained anatase TiO2, showed remarkable photocatalytic activity. Those samples sintered at 1000 °C were transformed to the rutile TiO2. The cell proliferation after 7–14-days culturing revealed that cells cultured on the 700 °C sample decreased in number immediately after initiation of culturing. The cells cultured on TiO2 sintered at 900 °C markedly proliferated over time with an increase in the alkaline phosphatase activity, showing good MC3T3-E1 cell compatibility of the samples. The sample sintered at 1000 °C, which is rutile TiO2, showed the highest increase.

Cold atmospheric pressure plasma jet prepares TiO2 coating on carbon fibre for field emission and explosive electron emission

As the ‘heart’ of high-current vacuum electronic devices, explosive emission cathodes play an important role in their applications. In this work, a titanium dioxide (TiO2)/carbon fibre cathode prepared by a cold atmospheric plasma jet is reported. TiO2 on the carbon fibre surface prepared by an atmospheric plasma jet is at the mixture of anatase and rutile phases. The field enhancement factor of the TiO2/carbon fibre cathode is 6681, which is over ten times higher than that of the carbon fibre cathode. Furthermore, the TiO2 coating slows the diode impedance collapse and decreases the cathode plasma expansion velocity from 1.5–2.0 to 1.0–1.5 cm µs−1, which is explained by a cathode plasma model. The surface of the TiO2/carbon fibre cathode is covered by 1.6 cm2 plasma, far exceeding that of the carbon fibre cathode (1.1 cm2), which enables uniform explosive electron emission. The obtained results show that TiO2/carbon fibre cathodes prepared by cold atmospheric plasma jets will be potential candidates as high-current explosive electron emitters.

Preliminary Study on Effect of Hydrothermal Temperature during TiO2 Synthesis on the Biodiesel Production from Waste Cooking Oil

In the present work, effect of hydrothermal temperature from 120 to 160 °C on TiO2 physicochemical properties as well as its photocatalytic activity towards biodiesel production using waste cooking oil (WCO) was investigated. TiO2was synthesized via hydrothermal method using Titanium butoxide, Ti(OBu)4 as the precursor and nitric acid, HNO3 as the peptizing agent. Next, the synthesized photocatalyst was dried at 60 °C for 24 h and later calcined at 400 °Cfor 2 h. The synthesized TiO2 was characterized using X-ray diffraction (XRD) and Burnauer- Emmet- Teller (BET) to determine their crystallinity and textural properties. Results showed that all synthesized TiO2 have a mixture of anatase and rutile phase and N2 adsorption- desorption isotherm for all catalyst possess Type IV isotherm according to IUPACclassification with hysteresis loop of type H1. Then, all the synthesized catalysts were tested for biodiesel production using esterified waste cooking oil under visible light irradiation for 1 h and 10 min. Percentage of fatty acid methyl ester (FAMEs) present in the synthesized biodiesel was determined using gas chromatography with flame ionization detector (GC-FID). The synthesized catalyst (T24_160) showed a good photocatalytic activity as the percentage of biodiesel yield was higher (3.41%) compared to the other catalyst.