Isopropoxide Precursor Research Articles

Photocatalytic nanocomposite based on pyrene functionalized reduced graphene oxide in situ decorated with TiO2 nanorods

Hybrid nanocomposites based on 1-pyrene carboxylic acid (PCA) functionalized High Porous Reduced Graphene Oxide (HPRGO) sheets, decorated with oleic acid (OLEA)-coated TiO2 nanocrystals (NCs), have been obtained by means of an in situ colloidal route, starting from titanium isopropoxide (TTIP) precursor, in presence of OLEA surfactant and trimethylamino-N-oxide dihydrate (TMAO) base catalyst. The effect of the synthesis parameters, namely the PCA-HPRGO:TTIP w/w and the OLEA:TTIP molar ratio, on the morphological, spectroscopic and structural properties of the nanocomposites, has been explored, to achieve highly crystalline TiO2 nanostructures, with a reproducible control on morphology and crystalline phase (anatase). The TiO2 NCs have been found to effectively heteronucleate and grow onto the –COOH groups of the PCA molecules anchoring onto the HPRGO basal plane by aromatic π-π stacking interactions. The OLEA ligand coordinating their surface endows the nanocomposites with dispersibility in organic solvents, with a morphology dictated by the PCA coordinating sites, OLEA, and the mode of the TMAO supply to the reaction mixture. A significantly higher coating density has been found for the TiO2 in nanorod (NR) morphology, which organize in a uniform and high packed layout onto the PCA-HPRGO basal plane. The TiO2 NRs decorated PCA-HPRGO nanocomposites (TiO2 NRs/PCA-HPRGO) have been tested as photocatalysts for the degradation of methyl red (MR) and nalidixic acid (NA) under UV- and solar-light irradiation. Their photocatalytic activity has been evaluated against TiO2 reference and commercial nanostructures and discussed in terms of electronic level alignment between the hybrid nanostructure components, considering the role of the PCA anchoring molecule at the interphase.

Optical Study on Co-Sensitization of Betanin Dye with Cadmium Sulfide to Fabricate Dye Sensitized Solar Cell

Natural dyes are low-cost, eco-friendly, readily available and have optical characteristics which render them useful in energy research. The titanium tetra isopropoxide precursor can be employed using sol-gel synthesis to get titanium dioxide nanoparticles (TiO2 NPs). The FESEM analysis confirmed the deposition of TiO2 NPs on Indium Tin Oxide (ITO) substrate, which is necessary for the photo-conversion mechanism to produce electricity. One of the natural dyes that is extracted from red beets is known as betanin dye (Bd). Due to their aligned energy levels, Bd and cadmium sulfide (CdS) are used together to provide effective optical characteristics, making them suitable as dye sensitizers. The presence of Cd-S, C-N and hydroxyl groups assigned to 500, 1633, and 3300 cm-1 respectively, was demonstrated by the FTIR analysis. The energy gap of 2.16, 2.13 and 2.2 eV for Bd, CdS and Bd-CdS composite was estimated using Tauc's plot and UV-visible spectra demonstrated maximum absorbance at 485, 510 and 528 nm, respectively. The Bd absorbs broad light in visible region due to the addition of CdS. The major charge-transport phenomenon in dye-sensitized solar cells (DSSC) involves an increase in photo-current density, due to its luminous nature. However, the recombination of charge carriers prevents the overall performance of the DSSCs. The power conversion efficiency of the DSSC constructed from Bd dye and Bd-CdS composite was 0.234% and 0.367%, respectively. This optical investigation suggests co-sensitization as a sure-fire method to improve the efficiency of DSSCs extracted from natural dyes, making them reliable for future indoor applications.

Enhanced photoelectric properties of TiO2 nanorod arrays through modulation of precursor concentration

This study synthesized titanium dioxide (TiO2) nanorod arrays and investigated their morphology and defect to the photoelectric response by varying the titanium isopropoxide (TTIP) precursor concentration from 0 to 66 mM. The vertically aligned rutile TiO2 nanorods exhibited film thicknesses ranging from 1 to 4.5 μm when the TTIP concentration equaled or exceeded 33 mM. Their rod length and diameter displayed a linear increase with the TTIP concentration. TiO2 arrays synthesized with a TTIP concentration of 33 mM exhibited the highest photoelectric response, measuring 52 μA/cm2 under xenon-lamp irradiation at a bias voltage of 0.8 V (vs. the Ag/AgCl reference). Notably, photoactivity was observed in the visible-light region as well. Photoluminescence spectra indicated a substantial reduction in electron-hole recombination compared to TiO2 arrays prepared from higher TTIP concentrations. X-ray photoelectron spectroscopy and electron paramagnetic resonance analyses confirmed the presence of oxygen vacancies. Time-resolved photoluminescence spectra corroborated an extended electron lifetime, suggesting that surface oxygen vacancies facilitated the separation of photoexcited charge carriers. The presence of oxygen vacancies, combined with the unique array morphology, resulted in enhanced photocurrent density.

Sol-Gel Spin Coated Transparent Single-TiO2 and SiO2 Thin Film on Glass for Opto-electronic Applications

Great attention has been given on the sol-gel synthesis and spin-coating deposition techniques for the fabrication of various thin films. Because of its simple technique to fabricate dielectric (metal oxide) films using tetraethyl orthosilicate and titanium isopropoxide precursors. In this work, transparent single layer of SiO2 and TiO2 thin film was deposited on a glass substrate and characterized by FTIR, UV-visible spectroscopy, fluorescence and scanning electron microscopy techniques. The single layer thin film was mechanically stable and strong by adhering to glass substrates. The FTIR transmittance spectrum evidenced the existence of Si-O-Si and Ti-O-Ti at ~1100 and 1400 cm-1. The UV-visible absorbance spectra of single layer of SiO2 and TiO2 thin films showed strong absorption at below 00 nm. The excitation wavelength at 380 nm, the fluorescence spectra of both thin films showed the highest emission spectrum in between 733-798 nm. The SEM studies confirmed the smooth surface in both SiO2 and TiO2 layers. Further, it could be useful for various applications such as back reflector in solar cells, anti-reflection coatings, hydrophobic and anti-fogging materials.

Composites based on polymeric blends reinforced with TiO2 modified aramid fibers

AbstractThe paper presents a study on composites based on 50:50 (PP:LLPE‐g‐MA) reinforced with 0.5, 1, and 2 wt% aramid fibers unmodified/modified with TiO2, processed by melt compounding. Micronic aramid fibers were acetone washed to remove impurities and treated with Ti(IV)isopropoxide precursor via sol–gel method, adding microcellulose for TiO2 particle dimension control. Composites were hot‐pressed into 4 mm‐thick plates for sampling and 0.5 mm‐thick sheets for thermoforming. All composites were successfully thermoformed, fibers‐based samples showing improved thermoforming ability without wrinkling. Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and Energy dispersive X‐ray spectroscopy (EDS) analysis confirmed the formation of TiO2 particles on the fiber surface. Optical microscopy, SEM and FTIR analysis exhibit the fibers' strong embedment into the matrix due to physical interlocking, generating surface defect reduction. Water absorption decreased from 0.195% (control) to 0.075 and 0% for 1 TiO2 and 2 TiO2 samples, due to material compactization. Contact angles increased from 95.18° (Control) to 108° (1 TiO2) and 112.89° (2 TiO2). The highest flexural strength and modulus were exhibited by 1 TiO2 sample that increased by 44.88% and 47.6% compared to the control sample, due to higher intrinsic rigidity of fibers and TiO2 modifying surface rugosity and phase interaction. The impact strength of the control sample improved by 139% compared to PP due to brittleness reduction, 1 TiO2 by 209% compared to PP, 29% compared to the control sample. The results and excellent thermoformability recommend the materials for encapsulation of electronic/expensive parts in automotive or drone applications, offering viable, facile, rapid, and cost‐effective solutions to easily replace damaged parts.Highlights Aramid fibers were successfully modified using isopropoxide precursor; Strong embedment of fibers in the polymer diminishes crack propagation/damage; Improved impact and bending properties and water contact angle; The composites showed a high ability to thermoform into complex shapes; Potential to replace non‐reusable materials as encapsulation solutions.

Hydrophilic sol-gel TiO2 coating on procaine-loaded injector needle for painless clinical treatments

Titanium dioxide (TiO2) coatings are demanded in clinical applications due to their biocompatible, porosity, and semiconducting properties. Drug release studies take advantage of these unique aspects of TiO2 for painless injection for those who have to take medicine through the injection frequently. In this study, TiO2 was prepared via the sol-gel method with Titanium tetra isopropoxide (TTIP) precursor in alcohol solvent for pH 3, 4, and 5 values. The prepared solution was coated on stainless steel substrates and injectors via dip coating. Following these steps, samples were calcinated at various temperatures (100°C, 300°C, 500°C, 700°C). The structural, physical, and chemical composition, chemical bond, wettability, and drug-release properties of coated samples were researched. Contact angle values affirmed that high temperatures and ultraviolet (UV)-light irradiation made samples more hydrophilic (26°±5° at 700°C for pH 4). Procaine, a short-time period local anaesthetic, was chosen as a model drug. Increased calcination temperature and raised hydrophilicity led to improve the released drug amount. Drug release studies were carried out using Franz diffusion cells at 36.5°C. Samples at 500°C calcinated released the highest amount of drug (90%) for 45 sec injection time. This study shed light on how TiO2 coating can be successfully utilized for clinical applications in the future.

Fabrication and Characterization of TiO2 Coatings on 304 Stainless-Steel Substrate for Efficient Oil/Water Separation

Oil spill accidents have been a prevalent threat to the environment. To aid in clean-up efforts, a stainless-steel filter with a hydrophilic and oleophobic coating was fabricated for efficient and affordable oil/water separation. Two solutions were used to deposit the coatings. One was sourced from a titanium (IV) isopropoxide (TTIP) precursor dissolved into 1-butanol and the other through the mixing of titanium dioxide nanopowder with glacial acetic acid. The solutions were applied to 304 stainless-steel mesh filters of varying aperture sizes ranging from 30 microns to 240 microns. The coating was applied through a multiphase deposition method followed by sintering at 450 °C. The filter performance was evaluated by contact angle measurement and a filtration test using a mixture of motor oil and water, while the surface morphology and structure of the coatings were characterized by SEM-EDS and XRD. The mesh with smaller aperture size showed oil retention improvement of up to 99%. The TiO2 nanopowder coating, with a 92% oil retention efficiency, outperformed the coating via the TTIP precursor.

Facile synthesis of carbon/titanium oxide quantum dots from lignocellulose-rich mandarin orange peel extract via microwave irradiation: Synthesis, characterization and bio-imaging application

A nanohybrid prepared from the lignocellulosic residue is a feasible approach to synthesize blue light emitting fluorescent doped TiO2 quantum dot nanocomposite (C-TiO2 QDs) by microwave techniques using Mandarin orange (Citrus reticulata) peel powder with titanium isopropoxide precursors. With a greater orange peel colloidal medium, the structure of the TiO2-NPs changed from a mixture of rutile and anatase phases to exclusively the anatase phase. The optical and morphological properties of as-prepared C-TiO2 QDs were characterized by HR-TEM, XRD, FT-IR, UV–visible, PL spectra, DLS, and Zeta potential techniques. The reaction condition was optimized by changing substrate composition, pH, and reaction time. C-TiO2 QDs exhibit outstanding stability at pH 7 and remain sustained for at least 180 days without aggregation. As prepared C-TiO2 QDs have distinct emission and excitation activities with an average particle size of 2.8 nm. Cell viability was performed on normal L929 cells, where it showed excellent biocompatibility (<90 %) even at the concentration of 200 μg/mL after 24 h treatment. Additionally, the synthesized C-TiO2 QDs were used with L929 cells as a fluorescent probe for bio-imaging applications. The results revealed that neither of the cell lines' morphologies had significantly changed, proving the biocompatibility of the synthetic C-TiO2 QDs.

Effect of applied voltage to the characteristic of TiO2 nanofibers fabricated using electrospinning technique

Titanium dioxide (TiO2) is an attractive semiconductor oxide compound due to its good stability properties both in chemical and photochemical. TiO2 in the form of nanofibers offers many advantages such as high surface area, flexibility of structures and mechanical properties such as stiffness and tensile strength. In this study, we reported the synthesis of TiO2 nanofibers using electrospinning technique. TiO2 nanofibers were produced from titanium (IV) iso-propoxide precursor solution at different applied voltages of 10 kV and 12 kV, while the flowrate was kept constant at 0.7 ml/hours during the process. The electrospinning process produced a thin layer of nanofibers which was then calcined for 1 hour at different calcination temperature. Based on the SEM images, we found that at applied voltage of 12 kV uniform and continuous nanofibers had already formed with the average diameter of nanofibers was in the order of sub microns. The diffraction pattern of TiO2 nanofibers shows that at a calcination temperature of 450°C, the phase was dominated by the anatase phase, while at 500°C it has a combination of anatase and rutile phases. Based on UV-Vis spectroscopy, it was found that the energy gap of TiO2 nanofibers calcined at temperature of 450°C and 500°C were 3.32 eV and 3.22 eV, respectively.

Development of kaolin and periwinkle shell ash Co-Doped TiO2 nanoparticles for degradation of hazardous dye

In the present study, the synthesis of periwinkle shell ash (PSA) doped into a highly exchanged kaolin-based nanocomposite photocatalyst was suggested. The novel nanocomposite was prepared in two-step synthesis using a sol–gel method with titanium isopropoxide precursor under hydrothermal treatment at 500 °C. The procedure resulted in the formation of [email protected]/TiO2 nanocomposite whose phase composition, particle morphology, chemical, and physical properties were characterized using XRD, SEM-EDX, HR-TEM, ATR-FTIR, and UV diffuse reflectance spectroscopy (UVDRS). The novel photocatalyst brilliantly photodegraded crystal violet dye (10 mg/L) at 99 % degradation efficiency for 300 mins of UV irradiation. The latter is attributed to the covering of photocatalyst surface by anatase/rutile titania nanoparticles, reduced bandgap (1.7,1.8 and 2.1 eV), and suppressed rapid recombination of the photogenerated electrons which originated from the metal–semiconductor interface. The commercial potential revealed possible application in the visible and ultraviolet wavelength, hydroxyl radical driven photodegradation, 700 % reusability rate, and predicted by multiple regression model. The enhanced [email protected]/TiO2 had shown absorption into Langmuir-Hinshelwood kinetics and high photocatalytic activity as the reaction mechanism. Therefore, the PSA and kaolin are cost-effective and efficient nanocomposites for the treatment of crystal violet dye effluents using UV–vis light.

Synergetic adsorption–photocatalysis process for water treatment using TiO2 supported on waste stainless steel slag

This study presents an economical and efficient method to decolourise dye wastewater using industrial waste stainless steel slag (SSS). Titanium dioxide was immobilised on SSS by a precipitation–calcination method. Samples with different TiO2 loadings (prepared using either titanium isopropoxide precursor or commercial TiO2 nanoparticles) were used to decolourise an organic contaminant (methylene blue) under dark and UV conditions in aqueous solution, and their adsorption and photocatalytic performances were compared. Samples with 15 and 25 TiO2 wt% prepared by the precursor method had normalised photocatalytic efficiencies per gram close to that of bare TiO2; using an adsorption–photocatalysis process led to efficiencies 4.4 and 1.6 times higher than that of pure TiO2. The improvement in catalytic performance (greater for samples with less than 50% TiO2 content) may be due to better UV absorption ability (related to with the improvement of TiO2 particle dispersion) and the close TiO2 support interaction, which can eventually cause a photocatalysis-enhancing shift towards more negative oxidation potentials. The SSS also acted as an efficient adsorption trap for organic compounds. The pollutant was thus transferred to the TiO2 surface and photodegraded more rapidly and efficiently. The outstanding synergetic adsorption–photocatalysis capacities of TiO2 waste stainless steel slag composites for dye water treatment made the proposed conversion approach have great potential in practical applications.Graphical abstract

Immobilised rGO/TiO2 Nanocomposite for Multi-Cycle Removal of Methylene Blue Dye from an Aqueous Medium

This work presents the immobilisation of titanium dioxide (TiO2) nanoparticles (NPs) and reduced graphene oxide (rGO)-TiO2 nanocomposite on glass sheets for photocatalytic degradation of methylene blue (MB) under different radiation sources such as ultraviolet and simulated solar radiation. The TiO2 NPs and rGO-TiO2 nanocomposite were synthesised through a simple hydrothermal method of titanium isopropoxide precursor followed by calcination treatment. Deposition of prepared photocatalysts was performed by spin-coating method. Additionally, ethylene glycol was mixed with the prepared TiO2 NPs and rGO-TiO2 nanocomposite to enhance film adhesion on the glass surface. The photocatalytic activity under ultraviolet and simulated solar irradiation was examined. Further, the influence of different water matrices (milli-Q, river, lake, and seawater) and reactive species (h+, •OH, and e−) on the photocatalytic efficiency of the immobilised rGO/TiO2 nanocomposite was careful assessed. MB dye photocatalytic degradation was found to increase with increasing irradiation time for both irradiation sources. The immobilisation of prepared photocatalysts is very convenient for environment applications, due to easy separation and reusability, and the investigated rGO/TiO2-coated glass sheets demonstrated high efficiency in removing MB dye from an aqueous medium during five consecutive cycles.

Synthesis of TiO 2 Using Calotropis gigantea for Visible Light Excitation and Degradation of Congo Red Dye

Green synthesized TiO2 (CG-TiO2) was prepared from Titanium isopropoxide (TTIP) precursor using aqueous leaf extract of Calotropis gigantea (CG). The CG-TiO2 was prepared with different mixing ratios of CG and TTIP varying from 1:3 to 1:5 and at different synthesis conditions, that is, mixing time, temperature, and calcination temperature. Morphological analysis indicated spherical nanoparticle clusters of CG-TiO2 with particles of an average size of 42 nm. The study indicated visible light excitation of CG-TiO2 and effective removal of Congo red from aqueous solution under visible light irradiation. A maximum Congo red removal efficiency of 97% was obtained within 2 h under the following conditions: Sample B (30 g leaves in 100 mL distilled water boiled for 2 h at 90°C); TTIP:CG – 1:3; mixing time and temperature – 2 h and 27°C, respectively; calcination temperature – 300°C.

THE EFFECT OF CALCINATION TEMPERATURE TO THE COMPOSITE CHARACTERISTICS OF TiO2SiO2 NANOPARTICLE

THE EFFECT OF CALCINATION TEMPERATURE TO THE COMPOSITECHARACTERISTICS OF TiO2SiO2 NANOPARTICLE. Self-cleaning material is a material that utilizes the photocatalytic property to degrade organic and inorganic compounds with the help of UV light. One of the materials that have good photocatalytic property is TiO2, the photocatalytic property causes TiO2 to be amphiphilic: becomes hydrophilic when there is light and becomes hydrophobic when there is no light. The photocatalytic property of TiO2 can be improved with the addition of buffer material such as SiO2. TiO2SiO2 nanoparticle was synthesized using a sol-gel method with Titanium (IV) Isopropoxide (TTIP) precursors for TiO2 and Tetraethyl Orthosilicate (TEOS) precursors for SiO2 and followed by a variation of calcination temperature of 400 °C, 450 °C, 500 °C, and 550 °C for 2 hours. TiO2SiO2 composite was synthesized using composition TiO2 sol 75% and SiO2 25%. The result of the synthesis TiO2SiO2 composite was characterized by Fourier Transform Infra-Red (FT-IR) instrument to determine the functional groups in the composites and X-Ray Diffraction (XRD) instruments to determine the phase, crystallite size and degree of crystallinity in the composite. The purpose of this research is to synthesized TiO2SiO2 nanoparticle as a self cleaning agent with variation of the calcination temperature, to obtain composite characteristics that can support self cleaning. The self-cleaning ability was based on a produced composite characteristic of TiO2SiO2. The result of FTIR characterization showed that at calcination temperature of 400 °C, 450 °C, 500 °C, and 550 °C there was a Ti-OSi bond at the peak of 948.91 cm-1, 950.77 cm-1, 941.13 cm-1, 942.13 cm-1. The result of XRD characterization showed that at the temperature of 400 °C had the best characteristics, the 75.27% anatase phase and brookite phase 24.72%. Calcinations temperature 400 °C had best degree of crystallinity of 91.66%.

Catalytic Performance of TiO2–Carbon Mesoporous-Derived from Fish Bones in Styrene Oxidation with Aqueous Hydrogen Peroxide as an Oxidant

The catalytic performance of titania-supported carbon mesoporous-derived from fish bones (TiO2/CFB) has been investigated in styrene oxidation with aqueous H2O2. The preparation steps of (TiO2/CFB) catalyst involved the carbonization of fish bones powder at 500 °C for 2 h. followed by impregnation of titania using titanium(IV) isopropoxide (500 µmol) precursor, and calcined at 350 °C for 3 h. The physical properties of the adsorbents were characterized using Fourier transform infrared, X-ray diffraction (XRD), Scanning electron microscopy with energy dispersive X-ray (SEM-EDX), and nitrogen adsorption-desorption studies. The catalytic test was carried out using styrene oxidation with H2O2 as an oxidant at room temperature for 24 h. Its catalytic activity was compared with Fe2O3/CFB, CuO/CFB, TiO2, and CFB catalysts. It is demonstrated that the catalytic activity of TiO2/CFB catalyst has the highest compared to Fe2O3/CFB, CuO/CFB, TiO2, and CFB catalysts in the oxidation of styrene with styrene conversion ~23% and benzaldehyde selectivity ~90%. Kinetics of TiO2/CFB catalyzed oxidation of styrene has been investigated and mechanism for oxidation of styrene has been proposed. Copyright © 2021 by Authors, Published by BCREC Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0).

Fabrication and Characterization of Zirconia Coating on the API5L Steel

Four layers of zirconia coating were applied on surface of API5 steel samples by sol-gel processing using zirconium isopropoxide precursor. In the first group of samples, after each layer of coating and for the second group after four layer coating, heat treatment of calcination and sintering is carried out at the desired temperature (350–550°C). X-ray diffraction and differential thermal analysis were used to evaluate the physicochemical reaction and phase changes caused by heat treatment of obtained gel. Microstructural features and corrosion resistance of coated samples were determined by SEM observation, microhardness and electrochemical corrosion testing respectively. The results show that by increasing of sintering temperature from 350 to 550°C, structure evolve from amorphous to crystalline state. For the first group of samples, sintering at 450°C and for the second group, sintering at 550°C, offer a more homogenous microstructure and higher resistance of corrosion.

Electrospun composite nanofibre adsorbents for effective removal of Cd2+ from polluted water

In this research, a novel three-dimensional material was produced through the combination of CNT, graphene and PAN/TTIP and the effect of MWCNT and graphene hybridization on TiO2 Nanofibers was studied. TiO2/PAN-(MWCNT/GO)-g-PCA Nanofibers were synthesized using multi-wall carbon Nanotubes-graft-poly citric acid (MWCNT-g-PCA), Graphene oxide-graft-poly citric acid (GO-g-PCA) and Polyacrylonitrile (PAN)/Titanium tetra isopropoxide precursors (TTIP) by electrospinning technique. The effective parameters such as the (MWCNT/GO)-g-PCA content, applied voltage, distance between needle and collector, (TTIP/PAN) precursors contents and feed rate were optimized. The Nanofibers were produced with the best morphology and characterized by FTIR, TG-DTA, SEM and XRD analysis. Prepared Nanofibers after calcination process used as Nano filter and Nanoadsorbent for complete removal of Cadmium ions from polluted water successfully.

Facile Synthesis of Iron-Titanate Nanocomposite as a Sustainable Material for Selective Amination of Substitued Nitro-Arenes

The fabrication of durable and low-cost nanostructured materials remains important in chemical, biologic and medicinal applications. Particularly, iron-based nanomaterials are of central importance due to the ‘noble’ features of iron such as its high abundance, low cost and non-toxicity. Herein we report a simple sol–gel method for the synthesis of novel iron–titanium nanocomposite-based material (Fe9TiO15@TiO2). In order to prepare this material, we made a polymeric gel using ferrocene, titanium isopropoxide and THF precursors. The calcination of this gel in air at 500 °C produced Fe-Ti bimetallic nanoparticles-based composite and nano-TiO2 as support. Noteworthy, our methodology provides an excellent control over composition, size and shape of the resulting nanoparticles. The resulted Fe-based material provides a sustainable catalyst for selective synthesis of anilines, which are key intermediates for the synthesis of several chemicals, dyes and materials, via reduction of structurally diverse and functionalized nitroarenes.

Calcium alginate-TiO2/SiO2 nanocomposite for glucose conversion to 5-hydroxymethylfurfural

The sodium alginate biopolymer used to form calcium alginate-TiO2/SiO2 nanocomposite has been successfully synthesized. The first stage is synthesis of TiO2/SiO2 composites by the sol-gel method using tetraethyl orthosilicate (TEOS) and titanium isopropoxide (TTIP) precursors. Calcium alginate nanocomposite is formed from the crosslinking process between Ca2+ ions from CaCl2.2H2O with sodium alginate combined with TiO2/SiO2 composites, characterized by Fourier Transform Infrared (FTIR), Scanning Electron Microscopy (SEM) and Tunneling Electron Microscopy (TEM). The average particle size of TiO2/SiO2 composite on the surface of calcium alginate obtained by TEM is about 50 nm. The application of calcium alginate-TiO2/SiO2 nanocomposite as catalyst is used for conversion of glucose into 5-hydroxymethylfurfural (HMF) using dimethyl sulfoxide (DMSO) solvents. The best glucose conversion obtained at 140 °C for 4 hours is 97 % and optimum HMF yield obtained at 140 °C and 5 hours is 40 %. Nanocomposites based on sodium alginate biopolymers combined with TiO2/SiO2 composites can be developed as new superior materials and promising catalysts because it is easily obtained and biodegradable.

Synthesis of ZrO2 nanoparticles and effect of surfactant on dispersion and stability

This work investigates the stability of dispersions of zirconium oxide nanoparticles, synthesized by the sol-gel method, with zirconium isopropoxide precursors. Nanofluids at concentrations of 0.1 wt% were prepared by dispersing the synthesized nanoparticles in deionized water. Anionic sodium dodecylbenzene sulfonate (SDBS), cationic cetyltrimethylammonium bromide (CTAB), and non-ionic polyvinyl pyrrolidone (PVP) at concentrations of 0.01 wt%, 0.03 wt%, and 0.05 wt% were used for nanoparticle dispersion. Stability was analyzed by means of dynamic light scattering (DLS), zeta potential, pH, visual inspection, and UV–vis. Transmission electron microcopy (TEM) images revealed particles with a size of 59.9 ± 13.5 nm, and x-ray diffraction (XRD) showed crystalline materials. The results of sedimentation, hydrodynamic radius, and absorbance indicate that the presence of surfactants reduces agglomeration and improves the stability of nanofluids over time. The non-ionic surfactant, PVP, produced a better effect on the hydrodynamic radius than its ionic counterparts (SDBS and CTAB). In addition, the type of surfactant was found to have a significant effect on the pH, zeta potential, and isoelectric point of the ZrO2 nanoparticles. Finally, the stability analysis revealed that stable nanofluids with a final concentration of 0.01 wt% of particles can be obtained after 20 days, demonstrating the potential of such nanofluids for heat transfer applications.