Adsorption behavior of methylene blue onto titanate nanotubes
Introduction
Titanium dioxide (TiO2) has been widely used in heterogeneous photocatalysis due to its stable physico-chemical property and high photocatalytic activity. Nanotubular TiO2-derived materials are particularly interesting since the discovery of carbon nanotubes in 1991 [1] and first fabrication of titania nanotubes in 1998 [2]. Among these, one-dimensional titanate nanotubes have attracted extensive attention for their particular morphology and unique physical and chemical properties. Such nanotubes can be synthesized via hydrothermal reaction between TiO2 and NaOH [3], [4], [5]. The obtained nanotubes exhibit multi-walled scroll-type open-ended structures and have large internal and external surfaces and interlayer spaces. These peculiar microstructures make titanate nanotubes have great potential for applications as adsorbents and photocatalysts. Several works [6], [7] have reported that titanate nanotubes with calcination post-treatment exhibit favorable photocatalytic activity.
It has been demonstrated that photocatalytic degradation rate depends on photocatalyst–pollutant molecule interaction and good adsorption of pollutant molecule can improve the efficiency of photocatalytic degradation [8], [9], [10]. The adsorption of pollutants is also of interest as it concerns other experimental studies, including photocatalyst surface modification [11], dye-sensitized photodegradation of organics [12], and so on. Obviously, it is of great importance to investigate the adsorption process of organic pollutants on the surface of titanate nanotubes to clarify the mechanism of photocatalytic reactions and facilitate the applications in contaminant destruction. Unfortunately, previous studies of titanate nanotubes focused on preparation, structure analysis and photocatalytic efficiency evaluation, and little attention were paid to identifying characteristic of organics adsorption onto titanate nanotubes. Furthermore, very few studies have been done with the focus on adsorption mechanism of organic pollutants on the surface of titanate nanotubes.
In the present work, titanate nanotubes (labeled as TNTs) were prepared by a hydrothermal reaction, whereafter the as-prepared nanotubes were calcined at a constant temperature. One of the familiar basic dyes, methylene blue (MB, Fig. 1), was employed as the model pollutant, and the adsorption of MB onto calcined titanate nanotubes (labeled as CTNTs) was systematically investigated. Specifically, the zeta potential at different pH for CTNTs suspension and attenuated total reflection-Fourier transform infrared (ATR-FTIR) spectra of MB adsorption onto CTNTs were measured, and adsorption mechanism of MB onto CTNTs was discussed.
Section snippets
Chemicals
MB (purity ≥98.5%, Beijing Chemical Reagents Company, Beijing, China) and TiO2 (P25, Degussa, Frankfurt, Germany) were used as received. According to the manufacturer, Degussa P25 contains approximately 90% anatase and 10% rutile. A 3000 mg/L stock MB solution was first prepared in deionized water. Other chemicals such as sodium hydroxide and ethanol were purchased as analytical reagent. All the solutions used in the experiment were prepared with deionized water.
CTNTs preparation
Titanate nanotubes were
Morphology and structures of titanate nanotubes
Fig. 2 showed the TEM images of the as-prepared products. One can see that a large amount of randomly tangled nanotubes was obtained. The hollow and open-ended characteristics of the TNTs can be observed from the TEM micrograph as shown in Fig. 2(a). The HRTEM image (see Fig. 2(b)) indicated that the prepared nanotubes had uniform inner (ca. 4.5 nm) and outer diameters (ca. 9 nm) along the length. Moreover, the as-prepared nanotubes possessed multi-walled tubular structures and generally
Conclusions
CTNTs were prepared through an alkaline hydrothermal treatment of TiO2 (Degussa P25) with 10 M NaOH aqueous solution followed by calcination in the air at 400 °C for 2 h. The morphology and structures of the nanotubes were well-preserved after calcination, keeping a scrolled multi-walled tubular configuration. The present study showed that the CTNTs, with the high surface area of 157.9 m2/g, had great adsorption capacities of MB. The equilibrium adsorption was attained in nearly 60 min. It was
Acknowledgements
The authors would like to acknowledge financial support from the Research Fund for the Doctoral Program of Higher Education (Grant No. 20070001045). Thanks are also to S.F. Weng from College of Chemistry and Molecular Engineering, Peking University for his assistance in ATR-FTIR analysis. The two anonymous reviewers are also gratefully acknowledged for their constructive comments and suggestions.
References (43)
- et al.
Effects of calcination temperature on the microstructures and photocatalytic activity of titanate nanotubes
J. Mol. Catal. A: Chem.
(2006) - et al.
Application of TiO2-mounted activated carbon to the removal of phenol from water
Appl. Catal. B
(2003) - et al.
A new route for preparation of TiO2/C hybrids and their photocatalytic properties
J. Mol. Catal. A: Chem.
(2006) - et al.
Kinetic study on the photo-catalytic degradation of pyridine in TiO2 suspension systems
Catal. Today
(2004) - et al.
Adsorption of dyes on nanosize modified silica particles
J. Colloid Interface Sci.
(1997) - et al.
Effects of sodium content and calcination temperature on the morphology, structure and photocatalytic activity of nanotubular titanates
J. Colloid Interface Sci.
(2007) - et al.
Adsorption kinetics of maxilon blue GRL onto sepiolite from aqueous solutions
Chem. Eng. J.
(2006) - et al.
Pseudo-second order model for sorption processes
Process Biochem.
(1999) - et al.
Adsorption kinetics and mechanism of cationic methyl violet and methylene blue dyes onto sepiolite
Dyes Pigm.
(2007) - et al.
Study of equilibrium, kinetic and thermodynamic parameters about methylene blue adsorption onto natural zeolite
Chem. Eng. J.
(2009)
Adsorption behaviour of methylene blue onto Jordanian diatomite: a kinetic study
J. Hazard. Mater.
Isotherms, kinetics and thermodynamics of acid dye adsorption on activated palm ash
Chem. Eng. J.
Kinetics and thermodynamics of methylene blue adsorption on Neem (Azadirachta indica) leaf powder
Dyes Pigm.
The adsorption kinetics of the cationic dye, methylene blue, onto clay
J. Hazard. Mater.
Kinetic and isotherm studies of Cu(II) adsorption onto H3PO4-activated rubber wood sawdust
J. Colloid Interface Sci.
Activated carbon from solid wastes using a pilot-scale batch flaming pyrolyser
Fuel
Adsorption of methylene blue on kaolinite
Appl. Clay Sci.
Evaluation of the use of raw and activated date pits as potential adsorbents for dye containing waters
Process Biochem.
Sorption dynamics and isotherm studies of methylene blue uptake on to palm kernel fibre
Chem. Eng. J.
Removal of methylene blue from colored effluents by adsorption on montmorillonite clay
J. Colloid Interface Sci.
Study of Pd(II) adsorption over titanate nanotubes of different diameters
J. Colloid Interface Sci.
Cited by (350)
Robust reduced graphene oxide-PDA/ZIF-8 aerogel composite for cyclic, high-capacity dye adsorption
2024, Separation and Purification TechnologyAn efficient and general oxidative magnetization for preparation of versatile magnetic porous biochar at low temperature
2024, Journal of Environmental Chemical EngineeringSuperparamagnetic titanate nanocomposites obtained from a polymorphic mixture of titanium dioxide
2024, Ceramics InternationalStudy on the adsorption performance of ZIF-8 on heavy metal ions in water and the recycling of waste ZIF-8 in cement
2023, Journal of Solid State Chemistry