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Nanomechanical properties, wear resistance and in-vitro characterization of Ta2O5nanotubes coating on biomedical grade Ti-6Al-4V

Sarraf M, Razak BA, Nasiri-Tabrizi B, Dabbagh A, Kasim NHA, Basirun WJ, et al.

J Mech Behav Biomed Mater, 2017 02;66:159-171.
PMID: 27886563 DOI: 10.1016/j.jmbbm.2016.11.012

Tantalum pentoxide nanotubes (Ta2O5NTs) can dramatically raise the biological functions of different kinds of cells, thus have promising applications in biomedical fields. In this study, Ta2O5NTs were prepared on biomedical grade Ti-6Al-4V alloy (Ti64) via physical vapor deposition (PVD) and a successive two-step anodization in H2SO4: HF (99:1)+5% EG electrolyte at a constant potential of 15V. To improve the adhesion of nanotubular array coating on Ti64, heat treatment was carried out at 450°C for 1h under atmospheric pressure with a heating/cooling rate of 1°Cmin-1. The surface topography and composition of the nanostructured coatings were examined by atomic force microscopy (AFM) and X-ray electron spectroscopy (XPS), to gather information about the corrosion behavior, wear resistance and bioactivity in simulated body fluids (SBF). From the nanoindentation experiments, the Young's modulus and hardness of the 5min anodized sample were ~ 135 and 6GPa, but increased to ~ 160 and 7.5GPa, respectively, after annealing at 450°C. It was shown that the corrosion resistance of Ti64 plates with nanotubular surface modification was higher than that of the bare substrate, where the 450°C annealed specimen revealed the highest corrosion protection efficiency (99%). Results from the SBF tests showed that a bone-like apatite layer was formed on nanotubular array coating, as early as the first day of immersion in simulated body fluid (SBF), indicating the importance of nanotubular configuration on the in-vitro bioactivity.

Matched MeSH terms: Titanium
Alignment efficiency and esthetic performance of 4 coated nickel-titanium archwires in orthodontic patients over 8 weeks: A multicenter randomized clinical trial

Ulhaq A, Esmail Z, Kamaruddin A, Meadows S, Daus J, Vitale M, et al.

Am J Orthod Dentofacial Orthop, 2017 Dec;152(6):744-752.
PMID: 29173854 DOI: 10.1016/j.ajodo.2017.07.014

INTRODUCTION: The objective of this 4-arm parallel study was to evaluate the alignment efficiency and esthetic performance of 4 coated nickel-titanium archwires over an 8-week period.
METHODS: Patients in the permanent dentition requiring maxillary and mandibular fixed orthodontic treatment with a preadjusted edgewise appliance were eligible for inclusion. Patients attending 4 hospital departments (United Kingdom and Italy) were randomly allocated to 1 of 4 treatment interventions: (1) BioCosmetic (Forestadent, Pforzheim, Germany), 0.017 in; (2) Titanol (Forestadent), 0.016 in; (3) TP Aesthetic (TP Orthodontics, La Porte, Ind), 0.014 in; and (4) Tooth Tone (Ortho Organizers, Calsbad, Calif) 0.016 in. Block randomization with block sizes of 4 and 8 was used to ensure an allocation ratio of 1:1:1:1. The primary outcome was alignment efficiency determined by the reduction in Little's irregularity index (mm). Secondary outcomes were color change using the Commission Internationale de L'Eclairage L*a*b* system and percentage of coating loss. Blinding was only applicable to outcome assessment of alignment efficiency. Regression models with Sidak's multiple comparison of means were used to analyze the data.
RESULTS: One hundred fifty patients (300 dental arches) were allocated to the treatment interventions, including 61 male and 89 female subjects with a mean age of 16.60 years. The average duration of follow-up was 63.65 days. Baseline characteristics for the archwire groups were similar. One patient was lost to follow-up. Five percent (n = 15) of the archwires fractured: BioCosmetic, 5.3% (n = 4); Titanol, 6.8% (n = 5); TP Aesthetic, 5.3% (n = 4); and Tooth Tone, 2.7% (n = 2). We analyzed 283 dental arches for alignment efficiency. There was no statistically significant difference for mean reduction in irregularity between the archwire groups (P = 0.627): BioCosmetic (n = 71), 3.86 mm (95% CI, 3.31-4.41); Titanol (n = 69), 4.51 mm (95% CI, 4.00-5.02); TP Aesthetic (n = 71), 4.13 mm (95% CI, 3.49-4.78); and Tooth Tone (n = 72), 4.21 mm (95% CI, 3.89-4.46). There was a statistically significant difference between archwire groups for color change (P = 0.001) and percentage of coating loss (P = 0.001), with BioCosmetic performing best in both parameters.
CONCLUSIONS: There was no difference between the archwires for alignment efficiency. BioCosmetic performed statistically significantly better than did the other groups for both color change and coating loss.
REGISTRATION: This trial was registered with the East Midlands NHS Research Ethics Committee (12/EM/0190).
PROTOCOL: The protocol was not published before trial commencement.

Matched MeSH terms: Titanium*
Luminescence characteristics of Li₂CO₃-K₂CO₃-H₃BO₃ glasses co-doped with TiO₂/MgO

Alajerami YS, Hashim S, Ghoshal SK, Ramli AT, Saleh MA, Ibrahim Z, et al.

Appl Radiat Isot, 2013 Dec;82:12-9.
PMID: 23948307 DOI: 10.1016/j.apradiso.2013.07.005

Understanding the influence of co-dopants in the luminescence enhancement of carbonate glasses is the key issue in dosimetry. A series of borate glasses modified by lithium and potassium carbonate were synthesized by the melt-quenching method. The glass mixture activated with various concentrations of TiO2 and MgO was subjected to various doses of gamma-rays ((60)Co). The amorphous nature of the samples was confirmed by x-ray diffraction (XRD) spectra. The simple glowing curve of the glass doped with TiO2 features a peak at 230°C, whose intensity is maximal at 0.5 mol% of the dopant. The intensity of the glowing curve increases with the concentration of MgO added as a co-dopant up to 0.25 mol%, where it is two times higher than for the material without MgO thermoluminescence properties, including dose response, reproducibility, and fading were studied. The effective atomic number of the material was also determined. Kinetic parameters, such as kinetics order, activation energy, and frequency factor are estimated. The photoluminescence spectra of the titanium-doped glass consist of a prominent peaks at 480 nm when laser excitation at 650 nm is used. A three-fold photoluminescence enhancement and a blue shift of the peak were observed when 0.1% MgO was introduced. In addition, various physical parameters, such as ion concentration, polaron radius and internuclear distances were calculated. The mechanism for the thermoluminescence and photoluminescence enhancements are discussed.

Matched MeSH terms: Titanium
Contour analysis of an implant--soft tissue interface

Chai WL, Moharamzadeh K, van Noort R, Emanuelsson L, Palmquist A, Brook IM

J Periodontal Res, 2013 Oct;48(5):663-70.
PMID: 23442017 DOI: 10.1111/jre.12062

Studies of peri-implant soft tissue on in vivo models are commonly based on histological sections prepared using undecalcified or 'fracture' techniques. These techniques require the cutting or removal of implant during the specimen preparation process. The aim of this study is to explore a new impression technique that does not require any cutting or removal of implant for contour analysis of soft tissue around four types of titanium (Ti) surface roughness using an in vitro three-dimensional oral mucosal model (3D OMM).

Matched MeSH terms: Titanium/chemistry
Fulltext Oral health-related quality of life (OHRQoL) of patients undergoing micro-osteoperforations (MOPs) to accelerate orthodontic space closure

Syed Bazli Alwi Syed Bakhtiar, Noraina Hafizan Norman, Sarah Haniza Abdul Ghani, Budi Aslinie Md Sabri

Compendium of Oral Science, 2017;4(1):19-27.
MyJurnal

Objectives: To assess and compare the oral health-related quality of life (OHRQoL) of orthodontic patients who had and had not undergone micro-osteoperforations (MOPs) during orthodontic space closure. Methods: 27 orthodontic patients with fixed appliance who are undergoing orthodontic space closure with Niti coil springs were given the validated short version of the Oral Health Impact Profile (Malaysia) Questionnaire (S-OHIP) which was available in both Bahasa Melayu and English, containing 14 items. 17 patients underwent MOPs (MOP group) while 10 patients did not (control). Additive scores (ADD) were calculated by summing the response codes for the 14 items and simple count scores (SC) were calculated by a count of the number of items reported as occurring ‘quite often’ and ‘very often’. Results: A total of 24 patients responded to the questionnaire, with a response rate of 88.9%, and they comprised of 79.2% females and 20.8% males. There is no significant difference in the mean ADD (p = 0.347) and mean SC (p = 0.446) across both groups. Conclusions: The reported oral health-related quality of life is similar for orthodontic patients who did and did not undergo MOPs.

Matched MeSH terms: Titanium
Surface characterization and corrosion behavior of calcium phosphate-base composite layer on titanium and its alloys via plasma electrolytic oxidation: A review paper

Rafieerad AR, Ashra MR, Mahmoodian R, Bushroa AR

Mater Sci Eng C Mater Biol Appl, 2015 Dec 1;57:397-413.
PMID: 26354281 DOI: 10.1016/j.msec.2015.07.058

In recent years, calcium phosphate-base composites, such as hydroxyapatite (HA) and carbonate apatite (CA) have been considered desirable and biocompatible coating layers in clinical and biomedical applications such as implants because of the high resistance of the composites. This review focuses on the effects of voltage, time and electrolytes on a calcium phosphate-base composite layer in case of pure titanium and other biomedical grade titanium alloys via the plasma electrolytic oxidation (PEO) method. Remarkably, these parameters changed the structure, morphology, pH, thickness and crystallinity of the obtained coating for various engineering and biomedical applications. Hence, the structured layer caused improvement of the biocompatibility, corrosion resistance and assignment of extra benefits for Osseo integration. The fabricated layer with a thickness range of 10 to 20 μm was evaluated for physical, chemical, mechanical and tribological characteristics via XRD, FESEM, EDS, EIS and corrosion analysis respectively, to determine the effects of the applied parameters and various electrolytes on morphology and phase transition. Moreover, it was observed that during PEO, the concentration of calcium, phosphor and titanium shifts upward, which leads to an enhanced bioactivity by altering the thickness. The results confirm that the crystallinity, thickness and contents of composite layer can be changed by applying thermal treatments. The corrosion behavior was investigated via the potentiodynamic polarization test in a body-simulated environment. Here, the optimum corrosion resistance was obtained for the coating process condition at 500 V for 15 min in Ringer solution. This review has been summarized, aiming at the further development of PEO by producing more adequate titanium-base implants along with desired mechanical and biomedical features.

Matched MeSH terms: Titanium/chemistry*
Nickel titanium springs versus stainless steel springs: A randomized clinical trial of two methods of space closure

Norman NH, Worthington H, Chadwick SM

J Orthod, 2016 Sep;43(3):176-85.
PMID: 26836747 DOI: 10.1080/14653125.2015.1122260

OBJECTIVE: To compare the clinical performance of nickel titanium (NiTi) versus stainless steel (SS) springs during orthodontic space closure.
DESIGN: Two-centre parallel group randomized clinical trial.
SETTING: Orthodontic Department University of Manchester Dental Hospital and Orthodontic Department Countess of Chester Hospital, United Kingdom.
SUBJECTS AND METHODS: Forty orthodontic patients requiring fixed appliance treatment were enrolled, each being randomly allocated into either NiTi (n = 19) or SS groups (n = 21). Study models were constructed at the start of the space closure phase (T0) and following the completion of space closure (T1). The rate of space closure achieved for each patient was calculated by taking an average measurement from the tip of the canine to the mesiobuccal groove on the first permanent molar of each quadrant.
RESULTS: The study was terminated early due to time constraints. Only 30 patients completed, 15 in each study group. There was no statistically significant difference between the amounts of space closed (mean difference 0.17 mm (95%CI -0.99 to 1.34; P = 0.76)). The mean rate of space closure for NiTi coil springs was 0.58 mm/4 weeks (SD 0.24) and 0.85 mm/4 weeks (SD 0.36) for the stainless steel springs. There was a statistically significant difference between the two groups (P = 0.024), in favour of the stainless steel springs, when the mean values per patient were compared.
CONCLUSIONS: Our study shows that stainless steel springs are clinically effective; these springs produce as much space closure as their more expensive rivals, the NiTi springs.

Matched MeSH terms: Titanium
Photocatalytic degradation of industrial pulp and paper mill effluent using synthesized magnetic Fe2O3-TiO2: Treatment efficiency and characterizations of reused photocatalyst

Subramonian W, Wu TY, Chai SP

J Environ Manage, 2017 Feb 01;187:298-310.
PMID: 27914351 DOI: 10.1016/j.jenvman.2016.10.024

In this work, heterogeneous photocatalysis was used to treat pulp and paper mill effluent (PPME). Magnetically retrievable Fe2O3-TiO2 was fabricated by employing a solvent-free mechanochemical process under ambient conditions. Findings elucidated the successful incorporation of Fe2O3 into the TiO2 lattice. Fe2O3-TiO2 was found to be an irregular and slightly agglomerated surface morphology. In comparison to commercial P25, Fe2O3-TiO2 exhibited higher ferromagnetism and better catalyst properties with improvements in surface area (58.40 m2/g), pore volume (0.29 cm3/g), pore size (18.52 nm), and band gap (2.95 eV). Besides, reusability study revealed that Fe2O3-TiO2 was chemically stable and could be reused successively (five cycles) without significant changes in its photoactivity and intrinsic properties. Additionally, this study demonstrated the potential recovery of Fe2O3-TiO2 from an aqueous suspension by using an applied magnetic field or sedimentation. Interactive effects of photocatalytic conditions (initial effluent pH, Fe2O3-TiO2 dosage, and air flow-rate), reaction mechanism, and the presence of chemical oxidants (H2O2, BrO3-, and HOCl) during the treatment process of PPME were also investigated. Under optimal conditions (initial effluent pH = 3.88, [Fe2O3-TiO2] = 1.3 g/L, and air flow-rate = 2.28 L/min), the treatment efficiency of Fe2O3-TiO2 was 98.5% higher than the P25. Based on Langmuir-Hinshelwood kinetic model, apparent rate constants of Fe2O3-TiO2 and P25 were 9.2 × 10-3 and 2.7 × 10-3 min-1, respectively. The present study revealed not only the potential of using magnetic Fe2O3-TiO2 in PPME treatment but also demonstrated high reusability and easy separation of Fe2O3-TiO2 from the wastewater.

Matched MeSH terms: Titanium/chemistry
Removal of VOCs from gas streams with double perovskite-type catalysts

Pan KL, Pan GT, Chong S, Chang MB

J Environ Sci (China), 2018 Jul;69:205-216.
PMID: 29941256 DOI: 10.1016/j.jes.2017.10.012

Double perovskite-type catalysts including La2CoMnO6 and La2CuMnO6 are first evaluated for the effectiveness in removing volatile organic compounds (VOCs), and single perovskites (LaCoO3, LaMnO3, and LaCuO3) are also tested for comparison. All perovskites are tested with the gas hourly space velocity (GHSV) of 30,000hr-1, and the temperature range of 100-600°C for C7H8 removal. Experimental results indicate that double perovskites have better activity if compared with single perovskites. Especially, toluene (C7H8) can be completely oxidized to CO2 at 300°C as La2CoMnO6 is applied. Characterization of catalysts indicates that double perovskites own unique surface properties and are of higher amounts of lattice oxygen, leading to higher activity. Additionally, apparent activation energy of 68kJ/mol is calculated using Mars-van Krevelen model for C7H8 oxidation with La2CoMnO6 as catalyst. For durability test, both La2CoMnO6 and La2CuMnO6 maintain high C7H8 removal efficiencies of 100% and 98%, respectively, at 300°C and 30,000hr-1, and they also show good resistance to CO2 (5%) and H2O(g) (5%) of the gas streams tested. For various VOCs including isopropyl alcohol (C3H8O), ethanal (C2H4O), and ethylene (C2H4) tested, as high as 100% efficiency could be achieved with double perovskite-type catalysts operated at 300-350°C, indicating that double perovskites are promising catalysts for VOCs removal.

Matched MeSH terms: Titanium/chemistry*
Preparation, and structural of new NiS-SiO2 and Cr2S3-TiO2 nano-catalyst: Photocatalytic and antimicrobial studies

Hosseini M, Fazelian N, Fakhri A, Kamyab H, Yadav KK, Chelliapan S

J. Photochem. Photobiol. B, Biol., 2019 May;194:128-134.
PMID: 30953914 DOI: 10.1016/j.jphotobiol.2019.03.016

NiS-SiO2 and Cr2S3-TiO2 synthesized by Ultrasound-Microwave method was tested for the photo-degradation of methyl red as azo dye under ultraviolet (UV) light. The structure and morphology of the synthesized materials were examined through scanning electron microscopy, X-ray diffraction and photoelectron spectroscopy, energy-dispersive spectroscopy, dynamic light scattering and the band gap energy differences were determined through diffuse reflectance spectroscopy (DRS). The crystallite size and band gap values of SiO2, TiO2, NiS-SiO2 and Cr2S3-TiO2-1 were obtained from XRD and UV-vis DRS analysis and found insignificant 44.22, 54.11, and 57.11 nm, and 8.9, 3.2, 3.0, 2.7 eV, respectively. The NiS-SiO2 and Cr2S3-TiO2 nanocomposites exhibited good stability and catalytic performance in the azo dye degradation; the composite provides a complete degradation after 50 min under UV irradiation. The effects of different quencher compounds on the Methyl red dye degradation were also investigated. The result for this experiment shows the system without the quencher was highly degradation of Methyl red. The antibacterial influence of the SiO2, TiO2, NiS-SiO2 and Cr2S3-TiO2-1 were studied versus two species bacteria. The antifungal performance of this nanoparticle was analyzed versus two species fungi as the C. albicans and P. funiculosum. Biological data demonstrated that the prepared catalyst has great bactericidal and fungicidal properties.

Matched MeSH terms: Titanium/chemistry*
Fulltext Detection of ethanol vapours using titanium dioxide (TiO2) catalytic pellet by conventional and modified sol gel dip-coating method

Tin, Ang Gaik, Mohamad Zailani Abu Bakar, Chen, Cheah Mooi

Pertanika Journal of Science & Technology, 2013;21(2):327-334.
MyJurnal

The present investigation deals with the development of ethanol-vapour-sensing materials coated with the semiconducting oxide TiO2. Thick films of anatase TiO2 were deposited using the sol-gel dip-coating technique on alumina substrates by conventional alkoxide sol and modified sol added with Degussa P-25 as the sensing medium. It was shown that crystallised TiO2 anatase was obtained at the annealing temperature of 500oC. The fabricated TiO2 sensors exhibited highest sensitivity at the sensing temperature of 350 ºC. Sensitivity towards the ethanol vapour was further increased with UV light effect. The enhancement of the sensitivity of the modified catalytic pellet can be explained by the crystallite of anatase TiO2 and the effect of the photocatalytic of TiO2. The high sensitivity of the TiO2 film deposited with modified sol revealed that the modified sol could be a new alternative in the development of a TiO2 ethanol sensor.

Matched MeSH terms: Titanium
Restoration of liquid effluent from oil palm agroindustry in Malaysia using UV/TiO2 and UV/ZnO photocatalytic systems: A comparative study

Ng KH, Khan MR, Ng YH, Hossain SS, Cheng CK

J Environ Manage, 2017 Jul 01;196:674-680.
PMID: 28365553 DOI: 10.1016/j.jenvman.2017.03.078

In this study, we have employed a photocatalytic method to restore the liquid effluent from a palm oil mill in Malaysia. Specifically, the performance of both TiO2 and ZnO was compared for the photocatalytic polishing of palm oil mill effluent (POME). The ZnO photocatalyst has irregular shape, bigger in particle size but smaller BET specific surface area (9.71 m2/g) compared to the spherical TiO2 photocatalysts (11.34 m2/g). Both scavenging study and post-reaction FTIR analysis suggest that the degradation of organic pollutant in the TiO2 system has occurred in the bulk solution. In contrast, it is necessary for organic pollutant to adsorb onto the surface of ZnO photocatalyst, before the degradation took place. In addition, the reactivity of both photocatalysts differed in terms of mechanisms, photocatalyst loading and also the density of photocatalysts. From the stability test, TiO2 was found to offer higher stability, as no significant deterioration in activity was observed after three consecutive cycles. On the other hand, ZnO lost around 30% of its activity after the 1st-cycle of photoreaction. The pH studies showed that acidic environment did not improve the photocatalytic degradation of the POME, whilst in the basic environment, the reaction media became cloudy. In addition, longevity study also showed that the TiO2 was a better photocatalyst compared to the ZnO (74.12%), with more than 80.0% organic removal after 22 h of UV irradiation.

Matched MeSH terms: Titanium*
Fulltext Facile hydrothermal preparation of titanium dioxide decorated reduced graphene oxide nanocomposite

Chang BY, Huang NM, An'amt MN, Marlinda AR, Norazriena Y, Muhamad MR, et al.

Int J Nanomedicine, 2012;7:3379-87.
PMID: 22848166 DOI: 10.2147/IJN.S28189

A simple single-stage approach, based on the hydrothermal technique, has been introduced to synthesize reduced graphene oxide/titanium dioxide nanocomposites. The titanium dioxide nanoparticles are formed at the same time as the graphene oxide is reduced to graphene. The triethanolamine used in the process has two roles. It acts as a reducing agent for the graphene oxide as well as a capping agent, allowing the formation of titanium dioxide nanoparticles with a narrow size distribution (~20 nm). Transmission electron micrographs show that the nanoparticles are uniformly distributed on the reduced graphene oxide nanosheet. Thermogravimetric analysis shows the nanocomposites have an enhanced thermal stability over the original components. The potential applications for this technology were demonstrated by the use of a reduced graphene oxide/titanium dioxide nanocomposite-modified glassy carbon electrode, which enhanced the electrochemical performance compared to a conventional glassy carbon electrode when interacting with mercury(II) ions in potassium chloride electrolyte.

Matched MeSH terms: Titanium/chemistry*
Preparation and characterization of tungsten-loaded titanium dioxide photocatalyst for enhanced dye degradation

Saepurahman, Abdullah MA, Chong FK

J Hazard Mater, 2010 Apr 15;176(1-3):451-8.
PMID: 19969415 DOI: 10.1016/j.jhazmat.2009.11.050

Tungsten-loaded TiO(2) photocatalyst has been successfully prepared and characterized. TEM analysis showed that the photocatalysts were nanosize with the tungsten species forming layers of coverage on the surface of TiO(2), but not in clustered form. This was confirmed by XRD and FT-Raman analyses where tungsten species were well dispersed at lower loading (<6.5 mol%), but were in crystalline WO(3) at higher loadings (>12 mol%). In addition, loading with tungsten could stabilize the anatase phase from transforming into inactive rutile phase and did not shift the optical absorption to the visible region as shown by DRUV-vis analysis. PZC value of TiO(2) was found at 6.4, but the presence of tungsten at 6.5 mol% WO(3), decreased the PZC value to 3. Tungsten-loaded TiO(2) was superior to unmodified TiO(2) with 2-fold increase in degradation rate of methylene blue, and equally effective for the degradation of different class of dyes such as methyl violet and methyl orange at 1 mol% WO(3) loading.

Matched MeSH terms: Titanium/chemistry*
Enhanced photocatalytic activity of fish scale loaded TiO2 composites under solar light irradiation

Ho LN, Ong SA, Osman H, Chong FM

J Environ Sci (China), 2012;24(6):1142-8.
PMID: 23505883

Fish scale (FS) loaded TiO2 composites were investigated as photocatalysts in degradation of Methyl Orange under solar light irradiation. Composites were prepared through sol-gel method by varying mass ratio of TiO2/FS at 90:10, 70:30 and 50:50, respectively. The catalysts prepared in this study were characterized by using XRD, SEM, FT-IR and nitrogen sorption. The effects of solar irradiation, mass ratio of TiO2/FS composites, irradiation time and catalyst loadings were studied. Synergistic effect was found in TiO2/FS of 90:10 composite which performed higher photocatalytic degradation than synthesized TiO2 under solar light irradiation. However, further increasing fish scale content in the composites reduced the photocatalytic activity drastically. Under solar light irradiation, all the catalysts in this study exhibited photocatalytic activity, except TiO2/FS of 50:50 composite that only acted as a weak biosorbent without performing any photocatalytic property. Photocatalytic degradation increased with increasing catalyst loading and irradiation time but decreased with increased of initial dye concentration.

Matched MeSH terms: Titanium/radiation effects; Titanium/chemistry*
Fulltext Transport and retention of engineered Al2O3, TiO2, and SiO2 nanoparticles through various sedimentary rocks

Bayat AE, Junin R, Shamshirband S, Chong WT

Sci Rep, 2015;5:14264.
PMID: 26373598 DOI: 10.1038/srep14264

Engineered aluminum oxide (Al2O3), titanium dioxide (TiO2), and silicon dioxide (SiO2) nanoparticles (NPs) are utilized in a broad range of applications; causing noticeable quantities of these materials to be released into the environment. Issues of how and where these particles are distributed into the subsurface aquatic environment remain as major challenges for those in environmental engineering. In this study, transport and retention of Al2O3, TiO2, and SiO2 NPs through various saturated porous media were investigated. Vertical columns were packed with quartz-sand, limestone, and dolomite grains. The NPs were introduced as a pulse suspended in aqueous solutions and breakthrough curves in the column outlet were generated using an ultraviolet-visible spectrophotometer. It was found that Al2O3 and TiO2 NPs are easily transported through limestone and dolomite porous media whereas NPs recoveries were achieved two times higher than those found in the quartz-sand. The highest and lowest SiO2-NPs recoveries were also achieved from the quartz-sand and limestone columns, respectively. The experimental results closely replicated the general trends predicted by the filtration and DLVO calculations. Overall, NPs mobility through a porous medium was found to be strongly dependent on NP surface charge, NP suspension stability against deposition, and porous medium surface charge and roughness.

Matched MeSH terms: Titanium
Fulltext Ultra-Sensitive Humidity Sensor Based on Optical Properties of Graphene Oxide and Nano-Anatase TiO2

Ghadiry M, Gholami M, Lai CK, Ahmad H, Chong WY

PLoS One, 2016;11(4):e0153949.
PMID: 27101247 DOI: 10.1371/journal.pone.0153949

Generally, in a waveguide-based humidity sensors, increasing the relative humidity (RH) causes the cladding refractive index (RI) to increase due to cladding water absorption. However, if graphene oxide (GO) is used, a reverse phenomenon is seen due to a gap increase in graphene layers. In this paper, this interesting property is applied in order to fabricate differential humidity sensor using the difference between RI of reduced GO (rGO) and nano-anatase TiO2 in a chip. First, a new approach is proposed to prepare high quality nano-anatase TiO2 in solution form making the fabrication process simple and straightforward. Then, the resulted solutions (TiO2 and GO) are effortlessly drop casted and reduced on SU8 two channels waveguide and extensively examined against several humid conditions. Investigating the sensitivity and performance (response time) of the device, reveals a great linearity in a wide range of RH (35% to 98%) and a variation of more than 30 dB in transmitted optical power with a response time of only ~0.7 sec. The effect of coating concentration and UV treatment are studied on the performance and repeatability of the sensor and the attributed mechanisms explained. In addition, we report that using the current approach, devices with high sensitivity and very low response time of only 0.3 sec can be fabricated. Also, the proposed device was comprehensively compared with other state of the art proposed sensors in the literature and the results were promising. Since high sensitivity ~0.47dB/%RH and high dynamic performances were demonstrated, this sensor is a proper choice for biomedical applications.

Matched MeSH terms: Titanium/chemistry*
Controlled Synthesis of Well-Aligned and Highly Ordered TiO₂ Nanotubes Without Bundling for Enhanced Solar-Powered Photoelectrochemical Responses

Lai CW, Lau KS, Chou PM

J Nanosci Nanotechnol, 2019 Dec 01;19(12):7934-7942.
PMID: 31196312 DOI: 10.1166/jnn.2019.16777

Using solar-powered water electrolysis systems for hydrogen generation is a key decision for the development of a sustainable hydrogen economy. A facile approach is presented in the present investigation to improve the solar-powered photoelectrochemical performance of water electrolysis systems by synthesising well-aligned and highly ordered TiO₂ nanotube films without bundling through the electrochemical anodisation technique. Herein, geometrical calculations were conducted for all synthesised TiO₂ nanotubes, and determination of the aspect ratio (AR) and geometric surface area factor (G) was achieved. On the basis of the collected data, well-aligned TiO₂ nanotubes with an AR of approximately 60 and G of approximately 400 m² ·g-1 were successfully formed in an electrolyte mixture of ethylene glycol with 0.3 wt% NH4F and 5 wt% H₂O₂ at 40 V for 60 min. The nanotubes were subsequently annealed at 400 °C to form anatase-phase TiO₂ nanotube films. The resultant well-aligned and highly ordered TiO₂ nanotube films exhibited a photocurrent density of 1.5 mA · cm-2 due to a large number of photo-induced electrons moving along the tube axis and perpendicular to the Ti substrate, which greatly reduces interfacial recombination losses.

Matched MeSH terms: Titanium
Application of doped photocatalysts for organic pollutant degradation - A review

Khaki MRD, Shafeeyan MS, Raman AAA, Daud WMAW

J Environ Manage, 2017 Aug 01;198(Pt 2):78-94.
PMID: 28501610 DOI: 10.1016/j.jenvman.2017.04.099

Advanced oxidation process involves production of hydroxyl radical for industrial wastewater treatment. This method is based on the irradiation of UV light to photocatalysts such as TiO2 and ZnO for photodegradation of pollutant. UV light is used for irradiation in photocatalytic process because TiO2 has a high band gap energy which is around 3.2 eV. There can be shift adsorption to visible light by reducing the band gap energy to below 3.2 eV. Doped catalyst is one of the means to reduce band gap energy. Different methods are used for doped catalyst which uses transition metals and titanium dioxide. The band gap energy of three types of transition metals Fe, Cd and Co after being doped with TiO2, are around 2.88 ev, 2.97ev and 2.96 ev, respectively which are all below TiO2 energy. Some of the transition metals change the energy level to below 3.2 eV and the adsorption shifts to visible light for degradation of industrial pollutant after being doped with titanium dioxide. This paper aims at providing a deep insight into advanced oxidation processes, photocatalysts and their applications in wastewater treatment, doping processes and the effects of operational factors on photocatalytic degradation.

Matched MeSH terms: Titanium*
State-of-the-Art on Functional Titanium Dioxide-Integrated Nano-Hybrids in Electrical Biosensors

Nadzirah S, Gopinath SCB, Parmin NA, Hamzah AA, Mohamed MA, Chang EY, et al.

Crit Rev Anal Chem, 2020 Sep 30.
PMID: 32997522 DOI: 10.1080/10408347.2020.1816447

Biosensors operating based on electrical methods are being accelerated toward rapid and efficient detection that improve the performance of the device. Continuous study in nano- and material-sciences has led to the inflection with properties of nanomaterials that fit the trend parallel to the biosensor evolution. Advancements in technology that focuses on nano-hybrid are being used to develop biosensors with better detection strategies. In this sense, titanium dioxide (TiO2) nanomaterials have attracted extensive interest in the construction of electrical biosensors. The formation of TiO2 nano-hybrid as an electrical transducing material has revealed good results with high performance. The modification of the sensing portion with a combination (nano-hybrid form) of nanomaterials has produced excellent sensors in terms of stability, reproducibility, and enhanced sensitivity. This review highlights recent research advancements with functional TiO2 nano-hybrid materials, and their victorious story in the construction of electrical biosensors are discussed. Future research directions with commercialization of these devices and their extensive utilizations are also discussed.

Matched MeSH terms: Titanium

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