Modified Titanate Nanotubes Research Articles

Performance of TFN nanofiltration membranes through embedding internally modified titanate nanotubes

Performance of TFN nanofiltration membranes through embedding internally modified titanate nanotubes

Photocatalytic disinfection of Coliforms and degradation of natural organic matters in river water using titanate nanotubes

ABSTRACT In this study, we synthesized and modified titanate nanotubes (TNTs) under different conditions of acid rinsing and calcination. The produced materials were then characterized by transmission electron microscopy, X-ray diffraction, ultraviolet–visible spectroscopy, temperature programmed desorption, inductively coupled plasma atomic emission spectroscopy, and Brunauer–Emmett–Teller analysis. The activity of material was evaluated via its application for disinfection of Coliforms and removal of natural organic matters (NOMs) in river water. Results showed that TNTs rinsed at pH 1.6 and calcined at 500°C had the highest removal efficiency for the treatment of Coliforms and NOMs in Sai Gon river water, possibly due to its high surface area, crystallinity, and surface acidity. The application of this TNTs material for the treatment of waters from Dong Nai River and Mekong River also show high removal efficiency, which could meet the quality standard for supply water, suggesting the potential of TNTs for practical drinking water treatment.

Enhanced Photocatalytic Degradation of Organic Pollutants and Anticorrosion of Mild Steel by Vanadium Modified Titanate Nanotubes (X%V‐TiNTs)

AbstractThe present work aims to study the anticorrosion and the photodegradation properties of titanate nanotubes (TiNTs) and vanadium doped‐titanate nanotubes (V‐TiNTs). Moreover, this article seeks to investigate the effect of doping TiNTs by vanadium species at different amount (2, 5 and 10 wt %). The raw materials (i.e:TiO2 and V2O5‐TiO2) are obtained by a sol gel process, while the hydrothermal treatment is chosen to achieve the hollow structure. The structural evolutions and morphological characteristics of materials have performed using various techniques such as: Scanning Electron Microscopy and Energy Dispersive X‐ray (MEB/EDS), X‐ray diffraction (XRD), UV‐Visible in Reflection Diffuse spectroscopy (RD/UV‐Vis) and Fourier Transform InfraRed spectroscopy (FTIR) analysis. However, the anticorrosion properties of the synthesized nanotubes are evaluated on mild steel corrosion in 1 N HCl using a weight loss method. All materials showed a potential inhibitor effect (up to 90 %) depending on the vanadium percentage and the inhibitor concentration. The photodegradation activity of the prepared materials is evaluated in the photodegradation of two organic pollutants: Methylene Blue (MB) and Malachite Green (MG) under UV‐Visible irradiation. The obtained results underlined the improvement of photocatalytic activity of TiNTs by vanadium species. A conversion rate up to 96 % is achieved at reduced time. Therefore, the prepared materials could be suitable for the anticorrosion of mild steel and the photodegradation of organic pollutants.

A comparative study on emergent pollutants photo-assisted degradation using ruthenium modified titanate nanotubes and nanowires as catalysts

Several methods have been used to tailor nanomaterials structure and properties. Sometimes, slight changes in the structure outcomes expressive improvements in the optical and photocatalytic properties of semiconductor nanoparticles. In this context, the influence of the metal doping and the morphology on a catalyst performance was studied in this work. Here, ruthenium doped titanate nanotubes (RuTNT) were synthesised for the first time using an amorphous Ru-containing precursor. Afterwards, the photocatalytic performance of this sample was compared to the one obtained for ruthenium titanate nanowires (RuTNW), recently reported. Two samples, RuTNW and RuTNT, were produced using the same Ru-containing precursor but distinct hydrothermal methodologies. The powders were structural, morphological and optical characterized by X-ray diffraction and fluorescence, transmission electron microscopy, Raman, X-ray photoelectron and photoluminescence spectroscopies. Distinct variations on the structural and optical properties of the RuTNT and RuTNW nanoparticles, due to ruthenium incorporation were observed. Their potential use as photocatalysts was evaluated on the hydroxyl radical photo-assisted production. Both samples were catalytic for this reaction, presenting better performances than the pristine counterparts, being RuTNT the best photocatalyst. Subsequently, the degradation of two emergent pollutants, caffeine and sulfamethazine, was studied. RuTNT demonstrated to be better photocatalyst than RuTNW for caffeine but identical performances were obtained for sulfamethazine. For both catalysts, the degradation mechanism of the pollutants was explored through the identification and quantification of the intermediate compounds produced and several differences were found. This indicates the importance of the structural and morphological aspects of a material on its catalytic performance.

Adsorption of Methylene Blue on Titanate Nanotubes Synthesized with Ultra-Small Fe3O4 Nanoparticles

Modified titanate nanotubes (TNT) were tested for their adsorption of methylene blue (MB) from water solutions. They were obtained from the TiO2 nanopowder using a standard alkaline hydrothermal method but in the stage of acid washing, when the titanate flakes begin to roll into nanotubes, magnetite nanoparticles were added. The Fe3O4 magnetic nanoparticles with diameter of around 2[Formula: see text]nm and 12[Formula: see text]nm were used in the tests. Significantly stronger adsorption of MB was observed when smaller nanoparticles were used compared to using larger nanoparticles and compared to the case of unmodified nanotubes. It was shown that the increased adsorption of MB is associated with a more negative value of [Formula: see text]-potential for titanates modified by the ultra-small nanoparticles. In the adsorption experiment, pH 7 was selected. These results may prove to be of great importance in the case of potential applications corresponding to the use of such material for wastewater purification.

Modified titanate nanotubes for the production of novel aliphatic polyurethane nanocomposites

Aliphatic polyurethane (PU) nanocomposites were prepared using modified titanate nanotubes (TNTs) as filler in order to improve the mechanical and thermal properties of the initial polymer. With a view to achieving greater interaction between the polymer chains and TNTs, the latter was functionalized with hexamethylene diisocyanate (H) and/or aminopropyl trimethoxysilane groups (A), producing the modified nanotubes TNTH, TNTA, or TNTHA. The thermogravimetric analyses used to quantify the amount of anchored diisocyanate or/and silanol groups in the nanotubes identified the H function as the best functional group in terms of improving the filler–PU compatibility. Transmission electron microscopy, field emission scanning electron microscopy, and atomic force microscopy analyses of the PU nanocomposites containing the three different fillers showed good TNT dispersion. The TNTHA nanotubes functionalized with both groups through the reaction between the H function already anchored on the TNTs and the A group, forming a monourea anchored group, significantly improved the mechanical and thermal properties of PU nanocomposites. POLYM. COMPOS., 40:2292–2300, 2019. © 2018 Society of Plastics Engineers

Adsorptive removal of emerging pollutants from groundwater by using modified titanate nanotubes

The increasing presence of chemicals and pharmaceuticals in rivers, lakes, and groundwater among others, represents a latent threat both to ecosystems and to human health. Conventional treatment methods for water hardly eliminate these pollutants, which are usually dissolved in low concentrations (μgL−1 or ngL−1). Therefore, the use of nanomaterials represents a viable alternative to eliminate them. Titanate nanotubes have been successfully used in adsorption of organic dyes as well as heavy metals, however, their use as an adsorbent of pharmaceuticals and other organic pollutants has been scarcely studied. In this work, unmodified titanate nanotubes as well as modified titanate nanotubes by using a surfactant, were synthesized and characterized to study the adsorption of six organic pollutants of interest through first and second order kinetic models, as well as, adsorption isotherms of Freundlich and Langmuir. The synthesized nanotubes showed good efficiency for the adsorption of persistent organic compounds, reaching a maximum adsorption percentage of 83%, 78%, 54%, 43%, 30% and 47% for 2,4,6-trichlorophenol, oxytetracycline, 2,4-dichlorophenol, tolazamide, captopril, and metformin respectively. Moreover, removal of pollutants was also successfully carried out in groundwater samples.

Adsorption of phenol from aqueous solutions using interlayer modified titanate nanotubes

AbstractBACKGROUNDLayered titanate nanostructures have long been studied as efficient adsorbents for different kinds of pollutants such as heavy metals and dye cations. As to the electro‐neutral and anionic organic pollutants, titanates show relatively low adsorption capacity due to a negatively charged surface and lack of organophilic affinity. This research focuses on the interlayer modification of titanate nanotubes for adsorption of this kind of organic pollutants. Phenol was chosen as a representative target.RESULTSTwo surfactants, hexadecyl trimethyl ammonium bromide (HTAB) and dodecyl dimethyl benzyl ammonium bromide (DDBAB), were chosen as organic modifier for the interlayer modification. Detailed characterization proved that surfactant molecules were intercalated into the interlayer and surface properties of titanates were successfully modified. Adsorption behavior of phenol was then systematically investigated. Results show that DDBAB modified titanates are efficient phenol adsorbents, possessing better performance than HTAB modified titanates. The high adsorption capacity is attributed to the special structure of titanates and the affinity between phenyl groups in DDBAB and phenol. Subsequently, thermally induced phase change of spent adsorbents led to complete regeneration.CONCLUSIONInterlayer modified titanate nanotubes were efficient phenol adsorbents with a maximum adsorption capacity of 226.24 mg g‐1. Complete regeneration of spent adsorbents was also achieved. © 2018 Society of Chemical Industry

Enhanced adsorption of Ag+ on triethanolamine modified titanate nanotubes

A novel high adsorption capacity adsorbent of triethanolamine modified titanate nanotubes (TEOA-TNTs) was prepared by simple hydrothermal process and modification technique. The FT-IR, XPS, Zeta-potential and nitrogen adsorption-desorption results showed that titanate nanotubes (TNTs) was successfully modified by triethanolamine (TEOA) via electrostatic interaction and laTEOA) via electrostatic interaction and lattice doping. The as-prepared TEOA-TNTs exhibited a significant enhancement on adsorption capacity towards Ag+ compared with TNTs. The adsorption isotherm of Ag+ on TEOA-TNTs fitted the Langmuir equation well and the maximum adsorption capacity of TEOA-TNTs for Ag+ was estimated to be 396mg/g at 25°C. The chelation and reduction mechanism of Ag+ on TEOA-TNTs was confirmed by the pseudo second-order adsorption kinetics assessments and the existence of metallic silver on TEOA-TNTs. Considering its relative simple preparation procedure, TEOA-TNTs can be a promising candidate for the recovery of Ag+ from the aqueous solution.

Preparation of Modified Titanate Nanotubes and Its Application in Polyurethane Nanocomposites

SummaryThis work presents the preparation of modified titanates nanotubes with tetraethyl orthosilicate (TNT‐TEOS) and their use in the synthesis of TNT‐TEOS/polyurethane nanocomposite by in situ polymerization. The filler was added in a proportion of 1% (w/w) relative to the polyol weight. The TNT‐TEOS presented a specific surface area of 127 m2/g lower than that obtained for TNT (177 m2/g). The addition of TNT‐TEOS in a polyurethane matrix promoted an increase in thermal stability of the polymer when compared to the pure PU and in crystallinity as observed by increase in melting and crystallization enthalpies. This effect can be attributed to good filler dispersion into polymer matrix and the interaction between the filler and the soft segments of the polyurethane.

Thermal and mechanical properties of polyamide 11 based composites reinforced with surface modified titanate nanotubes

Abstract The preparation of polyamide 11 (PA11) based composites reinforced with pristine and surface-modified titanate nanotubes (TTNT) is reported. Twin-screw melt compounding was used to produce composites with up to 2 wt% of TTNT. To enhance dispersion and TTNT compatibility with the thermoplastic, these were modified with cetyltrimethylammonium bromide (CTAB) and sodium dodecyl sulphate (SDS). Fourier transform infrared spectroscopy and thermogravimetry were used to demonstrate that surface modification prior to composite processing was successful, while scanning transmission electron microscopy combined with energy-dispersive X-ray analysis confirmed the retention of surfactants on TTNT in composites. Nevertheless, scanning and transmission electron microscopy revealed incomplete dispersion of TTNT inside polyamide. The improved wettability on the TTNT–PA11 interface was observed for composites comprising surface-modified TTNT. Consequently, these composites exhibited better thermal and mechanical properties than those containing pristine TTNT. A significant rise of the decomposition temperature was detected in composites containing TTNT modified with CTAB, while the uppermost increment of the storage and Young’s modulus (of about 35% and 26%, respectively) was achieved in the composite comprising 0.5 wt% of TTNT modified with SDS. The increase of the nanofiller content improved the yield strength and led to the drop in the strain at break.

Effects of heat and peroxide treatment on photocatalytic activity of titanate nanotubes

The influence of structural, morphological and surface properties on photocatalytic activity of pristine and modified titanate nanotubes was carefully described and discussed in the following study. Titanate nanotubes (TNTs) were prepared via alkaline hydrothermal synthesis route followed by acid washing at ambient conditions. The resulting high specific surface area nanotubular solids were further modified by two distinguished post-treatments: (i) heat-treatment in the temperature range from 300 to 700°C, and (ii) peroxide-treatment at room temperature. Bisphenol A (BPA), a well-known endocrine disrupting compound (EDC), was selected as a testing molecule to evaluate the photodegradation potency of the modified TNTs. The resulting BPA and TOC removals confirmed that crystallinity and BET surface area of examined heat-treated solids play a crucial role in governing the photooxidation reaction. Regarding the peroxide-treated TNTs, a nearly three-fold improvement in BPA removal was attained in comparison to the pristine TNTs, which can be attributed to the redox reaction of surface titanium(IV) peroxo groups. However, the exposure of anatase-based samples to the H2O2 medium resulted in deteriorated photocatalytic oxidation of the model compound, due to recovery of surface Ti3+ defect sites, leading to increased e−–h+ recombination and decreased oxygen adsorption. In addition, a carbon-based elemental analysis of the heat-treated TNTs (TNT_500) and standard TiO2 P25 stressed the potential of tailor-made crystalline TNTs to be applied as photocatalysts for long-term removal of aqueous organics, due to low accumulation of carbonaceous deposits during the photodegradation runs.

High performance Pd catalyst using silica modified titanate nanotubes (STNT) as support and its catalysis toward hydrogenation of cinnamaldehyde at ambient temperature

A Pd/STNT catalyst, with silica modified titanate nanotubes as support, exhibited significantly enhanced activity towards hydrogenation of cinnamaldehyde.

Sorption of Organic Compounds, Oxyanions, and Heavy Metal Ions on Surfactant Modified Titanate Nanotubes

The adsorption capacities and mechanisms of organic compounds with water solubilities (Sw) ranging from 55 to 75 000 mg/L, oxyanions, and heavy metal ions onto surfactant (hexadecyltrimethylammoniu...

Titanate nanotubes as support of solid base catalyst

Modified titanate nanotubes with enhanced basicity were synthesized by the incipient wetness impregnation of sodium titanate nanotubes (Na-TNT) with basic cations (Mg2+, K+, Ba2+, Zn2+). The essential morphology and mesoporosity of the nanotubes were maintained, as well as the tri-titanate structure, although in some cases (Mg2+) ion exchange and intercalation reactions brought about some contraction of the rolled titanate layers. Basic sites were probed with CO2 adsorption microcalorimetry and infrared spectroscopy, revealing strong (Qads>150kJmol−1), medium (150<Qads<120kJmol−1), and weak basic sites that were absent in Na-TNT. These sites could be identified correspondingly with IR bands for relevant carbonate and bicarbonate complexes. All modified TNT catalysts demonstrated high conversions for the COS and CS2 hydrolysis reactions at 553K, confirming the presence of important basic sites.

Titanate nanotubes-embedded chitosan nanocomposite membranes with high isopropanol dehydration performance

Titanate nanotubes (TNTs) are prepared by a hydrothermal method, and then modified with poly(aspartic acid). Subsequently, they are incorporated into chitosan (CS) to fabricate the modified TNTs (MTNTs)-embedded chitosan hybrid membranes supported by the polyacrylonitrile (PAN) membrane (CS-MTNTs/PAN) and utilized for isopropanol dehydration. The physicochemical properties including physical morphology, chemical interaction, hydrophilicity, crystallinity, thermal stability and free-volume of CS-MTNTs hybrid separation layers are characterized by SEM, FTIR, water contact angle, XRD, TG and PALS analysis, respectively. It is found that the modification of poly(aspartic acid) can apparently improve the interfacial morphology and compatibility between TNTs and membrane matrix. Moreover, the superior isopropanol dehydration performance of CS-MTNTs/PAN composite membranes compared to pure CS membrane is verified via pervaporation experiments, which can be ascribed to the strong hydrophilicity and tubular structure of TNTs. For 90 wt% aqueous solution of isopropanol, the CS-MTNTs/PAN composite membrane containing 6 wt% MTNTs acquires the highest permeation flux and separation factor of 1498 g/m 2 h and 6237 at 80 °C, respectively. These results indicate the promising application potential of nanotube-filled membranes in the pervaporative dehydration of alcohols.

Preparation of cadmium-zinc sulfide nanoparticles modified titanate nanotubes with high visible-light photocatalytic activity

Titanate nanotubes (TiNTs) were modified in situ with cadmium-zinc sulfide nanoparticles by an ultrasound ion-exchange method combined with a hydrothermal process. The target product (TiNTs/Cd 0.8Zn 0.2S) showed a wide visible-light response and high visible-light photocatalytic activity. Degradation efficiency of rhodamine B in water was up to 96.6% with 1 mg mL −1 of TiNTs/Cd 0.8Zn 0.2S photocatalyst under visible-light illumination for 90 min. The result demonstrated that the photocatalytic activity of TiNTs under visible-light illumination could be increased dramatically by modification with the ternary sulfide Cd 0.8Zn 0.2S nanoparticles.

Prussian Blue‐Modified Titanate Nanotubes: A Novel Nanostructured Catalyst for Electrochemical Reduction of Hydrogen Peroxide

AbstractPrussian blue (PB) modified titanate nanotubes (PB‐TiNT) have been synthesized by the reaction of Fe2+‐modified TiNT with hexacyanoferrate(III) ions. The rate constant for heterogeneous catalytic reaction between PB‐TiNT and H2O2 was found to be k=2×104 dm3 mol−1 s−1, which is an order of magnitude higher than the values of k reported for conventionally prepared, electrochemically deposited PB films. On the PB‐TiNT modified electrode with subnanomolar surface concentration of PB (Γ(PB)=2.8×10−11 mol/cm2), a stable, reproducible and linear response towards H2O2 was obtained in the concentration range 0.02–4 mM, with the sensitivity of 0.10 AM−1 cm−2 at −150 mV.

Application of temperature modified titanate nanotubes for removal of an azo dye from water in a hybrid photocatalysis-MD process

The presented studies have focused on application of modified titanate nanotubes (TNTs) for decomposition of Acid Red 18 in water. The TNTs were prepared via hydrothermal method. The post-treatment of TNTs was carried out by calcination of the as-received nanotubes at temperatures of 400–700 °C. The photocatalytic experiments revealed that the most active towards AR18 decomposition were TNTs calcinated at 600 °C (TNT600). However, the photocatalytic activity of the calcinated titanate nanotubes, regardless of the annealing temperature applied was found to be lower than that of P25. In the second step of the investigations, the TNT600 were applied for degradation of AR18 in a photocatalytic membrane reactor coupling photocatalysis with membrane distillation. The effect of photocatalyst loading on the effectiveness of degradation of AR18 was especially investigated. After 5 h of irradiation the amount of AR18 was lowered for ca. 67, 80 and 97% for TNT600 loadings of 0.1–0.5 g/dm 3, respectively. The mineralization of the organics was significantly lower than the decolorization of the solution. The amount of TOC after 5 h of the experiment decreased for 20, 27 and 57%, for 0.1–0.5 g TNT600/dm 3, respectively. Amongst products and by-products of AR18 photodegradation organic acids (formic, acetic and oxalic) and inorganic ions (nitrite, nitrate, ammonia and sulfate) were detected. The product of the hybrid process (distillate) was high quality water with conductivity in the range of 2.3–3 μS/cm.

Preparation of Octadecyl and Amino Mixed Group Modified Titanate Nanotubes and Its Efficient Adsorption to Several Ionic or Ionizable Organic Analytes

In this study, octadecyl (C(18)) and aminopropyl group modified titanate nanotubes (C(18)/NH(2)-TNs) were prepared successfully with a silylation method by introducing octadecyltrimethoxysilane (ODS) and aminopropyltrimethoxysilane (APS) simultaneously to the surface of titanate nanotubes (TNs). The properties of the products were characterized in detail. The results indicated that there might be steric hindrance effects to C(18) groups on the nanoscaled interior and exterior space of TNs. Therefore, aminopropyl groups were more ready to immobilize on the surface of TNs than C(18) groups when the organosilanes ODS and APS coexisted in reaction solution. C(18)/NH(2)-TNs with the obvious characteristic of C(18) and aminopropyl groups were obtained as the ratio of ODS/APS in reaction solution was 4.0, and the corresponding proportion of the two groups (C(18)/NH(2)) on the C(18)/NH(2)-TN surface was about 0.25. This adsorbent had good water dispersibility, overcoming the bad deficiency of reverse phase nanosized materials in water and improving its accessibility to polar analytes. Due to the cooperative effect of alkyl and aminopropyl groups coupled with the residual hydroxyl groups on the surface, C(18)/NH(2)-TNs exhibited excellent affinity efficiency to some ionic or ionizable organic analytes under a different solution pH, including anionic (perfluorooctane sulfonate, perfluorooctanoic acid, and sodium dodecyl sulfate), cationic (cetyltrimethylammonium bromide), and amphoteric compounds (sulfamethazine). The selective binding of these anionic, amphoteric, and cationic analytes could be achieved by adjusting solution pH to acid, neutral, and alkaline conditions, respectively. Since C(18)/NH(2)-TNs possessed relatively large surface areas and strong affinity ability to ionic analytes, especially with long alkyl chains, it showed significantly higher adsorption capacity for perfluorooctane sulfonate than activated carbon and anion-exchange resin.