Preferential adsorption behavior of methylene blue dye onto surface hydroxyl group enriched TiO2 nanotube and its photocatalytic regeneration (original) (raw)
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Removal of methylene blue (MB) via adsorp-tion and photocatalysis using titanate nanotubes (TNTs) with different surface areas were investigated and compared to commercial titanium dioxide (TiO 2) P25 Degussa nanoparticles. The TNTs with surface area ranging from 20 m 2 /g to 200 m 2 /g were synthesized via hydrothermal method with different reaction times. TEM imaging confirmed the tubular structure of TNT while XRD spectra indicated all TNTs exhibited anatase crystallinity. Batch adsorption rate showed linearity with surface properties of TNTs, where materials with higher surface area showed higher adsorption rate. The highest MB adsorption (70%) was achieved by TNT24 in 60 min whereas commercial TiO 2 exhibited the lowest adsorption of only 10% after 240 min. Adsorption iso-therm studies indicated that adsorption using TNT is better fitted into Langmuir adsorption isotherm than Freundlich isotherm model. Furthermore, TNT24 was able to perform up to 90% removal of MB within 120 min, demonstrating performance that is 2-fold better compared to commercial TiO 2. The high surface area and surface Bronsted acidity are the main reasons for the improvement in MB removal performance exhibited by TNT24. The improvement in surface acidity enhanced the adsorption properties of all the nanotubes prepared in this study.
An Overview: Recent Development of Titanium Oxide Nanotubes as Photocatalyst for Dye Degradation
International Journal of Photoenergy, 2014
Today, organic dyes are one of the largest groups of pollutants release into environment especially from textile industry. It is highly toxic and hazardous to the living organism; thus, the removal of these dyes prior to discharge into the environment is essential. Varieties of techniques have been employed to degrade organic dyes and heterogeneous photocatalysis involving titanium dioxide (TiO2) appears to be the most promising technology. In recent years, TiO2nanotubes have attracted much attention due to their high surface area and extraordinary characteristics. This paper presents a critical review of recent achievements in the modification of TiO2nanotubes for dye degradation. The photocatalytic activity on dye degradation can be further enhanced by doping with cationic or anionic dopant.
Jurnal Rekayasa Kimia & Lingkungan, 2021
Synthetic dyes waste from textile industries, produce of the problematic pollutants in wastewater. TiO2 based photocatalysis are materials that exhibit excellent absorption behavior for organic compounds in wastewater due it properties including nontoxicity, high photocatalysis degradation ability, and chemical stabilities. However, several challenges exist regarding TiO2 nanotubes pure applications for dyes degradation such as poor affinity, high band gap energy, and difficulty of recovery and easy to recombination so it would decrease effectiveness of the photocatalysis process. Therefore, more design and optimization testing need to be conducted on the treatment conditions in order to reach higher removal efficiencies with lower costs. The modified physical properties by adding metal dopant, nonmetal, and sensitizer significantly enhanced photocatalysis activity. These parameters, which affect photocatalysis activity on degrade dyes waste pollutants, are discussed in the current ...
Adsorption and Degradation Kinetics of Methylene Blue on As-prepared and Calcined Titanate Nanotubes
Athens Journal of Sciences, 2018
Titanate nanotubes were prepared by hydrothermal synthesis, followed by Titanate nanotubes were prepared by hydrothermal synthesis, followed by proton exchange, and calcined at 250°C for 2h. The properties of prepared nanotubes were investigated with field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), adsorption-desorption N 2 isotherms and UV-Vis diffuse reflectance spectroscopy (DRS). As-prepared sample displayed strongly aggregated nanotubes with crystal structure of H 2 Ti 2 O 5 ×H 2 O. Calcination yielded with loss of interlayer water and partial transformation of nanotubes to anatase phase. Adsorption and photocatalytic decomposition of methylene blue, used as a model pollutant, on as-prepared and calcined titanate nanotubes have been studied. It was established that calcination at 250°C for 2h improves the adsorption and photocatalytic properties of titanate nanotubes. It was shown that pseudo-second-order model was the most appropriate to describe adsorption of methylene blue on titanate nanotubes. Affinity toward methylene blue of 48.45mg g-1 and 95.24mg g-1 has been established for as-prepared and calcined titanate nanotubes, while equilibrium adsorption was attained in 120min. Adsorption process is controlled by intraparticle diffusion and surface sorption in both samples, but the contribution of surface sorption is greater for the calcined sample. The pseudo-first-order kinetic is an acceptable model for photocatalytic dye degradation process on titanate nanotubes. It was shown that the calcination slightly increased the photocatalytic activity of titanate nanotubes.
Improved production of titanate nanotubes by hydrothermal method for adsorption of organic dyes
Beni-Suef University Journal of Basic and Applied Sciences, 2021
Background Increasing the yield of nanomaterials using the same reactor size and fixing most of the reactants and conditions will greatly improve the production process by saving time, energy and efforts. Titanate nanotubes are mainly prepared by hydrothermal process, in which TiO2 powder reacts with NaOH at certain conditions to form the desired nanotubes. It was reported that it is a must to use high concentrations of NaOH (10 N) to enable the tubular form formation, and the amount of NaOH from the stoichiometry point of view is much higher than that of TiO2; this means excess amounts of NaOH are not used and washed off. This work was designed to improve the production yield by making use of this excess amount of NaOH. Results More than 60 g of sodium titanate nanotubes was prepared using simple hydrothermal method. The prepared nanotubes were characterized by X-ray powder diffraction, high-resolution transmission electron microscopy, Fourier-transform infrared spectroscopy and BE...
Industrial & Engineering Chemistry Research, 2009
The photocatalytic degradation of a model textile dye, methyl orange (MO), using anodized titanium dioxide (TiO 2) nanotubes has been investigated. The effects of light intensity, dye concentration, external bias, pH, and nanotube dimensions (length, diameter, and wall thickness) on MO photodegradation have been examined. The application of a minimal bias of +0.0 versus saturated calomel electrode (SCE) can enhance the dye degradation at least 10 times compared to unbiased conditions for dye concentrations between 20 and 100 µM. The overall initial dye degradation rate demonstrates three types of dependence on dye concentration over a range from 2.5-100 µM. For lower dye concentrations (2.5-40 µM) and natural pH (∼6.0) conditions, Langmuir-Hinshelwood (LH) kinetics was observed. The nanotubes diameter, calcination condition, and the anatase-to-rutile ratio in the crystalline TiO 2 nanotubes together influence the photocatalytic and photoelectrochemical properties of the TiO 2 nanotubes.
2ND INTERNATIONAL CONFERENCE ON EMERGING SMART MATERIALS IN APPLIED CHEMISTRY (ESMAC-2021): ESMAC-2021
Sustainable and suitable cost-effective adsorbent as well as photocatalyst titanate nanotubes (TNTs), were synthesized hydrothermally, were characterised by XRD, SEM/EDX, and TEM. The nanotubes were used to remove Reactive Blue 21 (RB21) from aquatic environment through adsorption/degradation. Experiments were conducted at 25±2 o C. Adsorption study was conducted in dark; whereas photo-degradation in UV-light with a sufficient amount of oxygen in the suspension. Adsorptive behaviour evaluated to be 42.91 mg RB/g TNT from Langmuir isotherm. Dimensionless parameter (RL <1) suggested the favourable adsorption, whereas positive ΔG o value suggested the nonspontaneity of the process. Regeneration and its reuse suppressed the lower efficiency. Adsorption followed the pseudosecond-order reaction model. A probable photodegradation mechanism was proposed.
The influence of titanium dioxide phase composition on dyes photocatalysis
Journal of Sol-Gel Science and Technology, 2011
A comparative study of TiO 2 powders prepared by sol-gel methods is presented. Titanium tetraisopropoxide was used as the precursor for the sol-gel processes. The effects of the annealing treatment on phase, crystallite size, porosity and photodegradation of dyes (methyl orange and methylene blue) were studied. The phase structure, microstructure and surface properties of the films were characterized by using X-ray diffraction (XRD) and Atomic Force Microscopy (AFM). The X-ray diffraction was used for crystal phase identification, for the accurate estimation of the anatase-rutile ratio and for the crystallite size evaluation of each polymorph in the samples. It was found that the only TiO 2 anatase phase of the synthesized TiO 2 develops below 500°C, between 600 and 800°C the anatase coexist with rutile and above 800°C only the rutile phase was found in the samples. Attention has been paid not only to crystal structures, but also to the porosity, the particle size and the photocatalytic properties. However, the annealing temperature was found to have significant influence on the photocatalytic properties. Different TiO 2 doctor blade thin films were obtained mixing the sol gel powder (100% anatase) and TiO 2 Aldrich with TiO 2 Degussa P25. The surfactant (Triton X100 or sodium dodecyl sulfate) affects the packing density of the particles during deposition and the photocatalytic degradation efficiency of the dyes. The photocatalytic degradation kinetics of methyl orange and methylene blue using TiO 2 thin film were investigated.
Carbon Modified TiO2 Photocatalyst with Enhanced Adsorptivity for Dyes from Water
Catalysis Letters, 2009
A new photocatalyst was obtained by modification of commercial anatase TiO 2 (Police, Poland) in a pressure reactor in an ethanol atmosphere at 120°C for 4 h. The photocatalytic activity of the new material was tested during three azo dyes decomposition: monoazo (Reactive Red 198), diazo (Reactive Black 5) and poliazodye (Direct Green 99). The obtained photocatalyst had new bands at 1,440 cm-1 attributed to CO groups. UV-Vis/DR spectra of the photocatalyst also were changing and had an insignificant decrease in the visible region of the spectra. The amount of hydroxyl radicals produced on carbon-modified TiO 2 was a little higher than for the pristine one. The carbon modification also changes the Freundlich model of dyes adsorption to Langmuir model of adsorption. Additionally, it increases the monolayer capacity of modified TiO 2. As a result we observed a clear increase of the photocatalytic activity of carbonmodified TiO 2 sample.