The fabrication of TiO2-supported clinoptilolite via F− contained hydrothermal etching and a resultant highly energetic {001} facet for the enhancement of its photocatalytic activity (original) (raw)
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RSC Advances, 2021
TiO 2-supported clinoptilolite (TiO 2 /CP) was synthesized in the presence of F À ions. Various characterizations demonstrated that the particle size of loaded TiO 2 increased linearly with an increase in the temperature and concentration of F À ions. In particular, the additive F À ions were favored to produce the mutually independent co-exposed {001} and {101} facets of loaded TiO 2 , while TiO 2 /CPs synthesized in the absence of F À ions were dominated by the thermodynamically stable {101} facet. As photocatalysts for the removal of crystal violet or methyl orange dyes under UV-irradiation in aqueous solutions, TiO 2 / CPs (ACP6) synthesized in the presence of F À ions significantly improved the degradation efficiency, as compared to ACP3 obtained in the absence of F À ions. These results elucidated that the highly energetic {001} exposed facet, large particle size and fine dispersion of loaded TiO 2 in TiO 2 /CP accounts for its best photocatalytic performance. The effected mechanism of operational parameters on the degradation performances is proposed.
International Journal of Hydrogen Energy, 2018
The water splitting process for hydrogen production was investigated over a series of TiO 2deposited Clinoptilolite photocatalysts assessing the individual and synergistic effects of acid/alkaline and ion exchange treatments of Clinoptilolite as a support on the physicochemical properties and photocatalytic performance. The as-synthesized photocatalysts were characterized by XRD, BET, FESEM, EDX, FTIR, PL, and UVevis techniques. Based on the FESEM, EDX and BET techniques, higher dispersion of Ti species and an increased accessibility of the micro-channels could be achieved using modified Clinoptilolite supports due to their better textural properties. The fine dispersion of TiO 2 particles reflects higher surface density of active sites and separation efficiency of electronehole pairs, which accounts for their better photocatalytic performance. The characterization results generally indicated the remarkable synergetic effect of alkaline treatment on the surface morphology and TiO 2 dispersion, especially when it is coupled with NH 4 NO 3 treatment. The photocatalytic tests illustrated that employing the treated Clinoptilolite supports increases the photocatalytic activity up to 12e57%. It was found that TiO 2 supported on the alkaline Clinoptilolite followed by NH 4 NO 3 treatment effectively splitted water to hydrogen by 896:8 mmol g À1 TiO2 h À1 hydrogen production rate. The results indicate that the ion exchange-alkaline treatment of Clinoptilolite could provide strong basic sites and mesopore structure (average pore diameter of 21.65 nm) with high surface area (73.43 m 2 g À1) and well dispersion ability to improve the photocatalytic activity of TiO 2 /Clinoptilolite composite for hydrogen evolution.
TiO2/clinoptilolite composites for photocatalytic degradation of anionic and cationic contaminants
Journal of Materials Science, 2013
The present work aims to study the bulk and surface properties of the TiO 2 /clinoptilolite composite on the crystalline structure, superficial area, bandgap energy, zeta potential, particle size distribution, and chemical composition; in order to analyze the effect of the clinoptilolite proportion in the photocatalytic degradation of pollutants. TiO 2 /clinoptilolite composites were prepared by adding different mass proportions of clinoptilolite to a solgel bath containing TiCl 4 as the titania precursor. Surface charge studies explain the larger sensitivity to composite ratio observed in the photocatalytic degradation of anionic pollutants than in cationic dyes. An optimum TiO 2 /clinoptilolite ratio of 90/10 was found to be the most efficient in terms of lower tendency to agglomeration, largest surface area, and increased crystallite size. Improvement in composite surface area occurs only at low clinoptilolite wt% and seems to be caused by lower agglomeration of nanometric TiO 2 and acid-induced porosity in the zeolite.
Clinoptilolite-supported TiO 2 (TiO 2 /CP MOCVD ) has been synthesized by metal organic chemical vapor deposition method (MOCVD). Titanium precursor was evaporated at 110 °C under nitrogen flow rate to promote the surface interaction between titanium species and clinoptilolite. The effect of titanium precursor on the crystalline structure and the surface area of clinoptilolite were investigated by scanning electron microscopy (SEM), X-ray diffraction (XRD), transformed infrared spectroscopy (FT-IR), Raman spectroscopy, and Brunauer-Emmett-Teller measurement. XRD and SEM results indicate that TiO 2 precursor interacted with the support, decreasing the crystallinity of the clinoptilolite. The analysis by FT-IR spectroscopy further confirms that the titanium species were bound to clinoptilolite through Ti-O-Si bonds. The TiO 2 /CP MOCVD catalyst showed a mesoporous structure with the distribution of pores in several dimensions 3.7-7.1 nm, with high specific surface area (~ 471 m 2 /g). MOCVD improved the adsorption capacity of the catalyst surface towards the pollutants. TiO 2 / CP MOCVD particles turn yellow after adsorption of salicylic acid. The development of the yellow color is a clear indication of the formation of charge transfer titanium (IV) salicylate surface complex. Photocatalytic decomposition of SA in aqueous solution was carried out using TiO 2 /CP MOCVD . Experimental results revealed that TiO 2 /CP MOCVD required shorter irradiation time (120 min) for complete decomposition of SA than commercial P25 Degussa and TiO 2 /CP imp (clinoptilolite-supported TiO 2 using impregnation method). The TiO 2 /CP MOCVD can be recycled at least four times without loss in activity, indicating their magnificent stability.
Separation and Purification Technology, 2017
Clinoptilolite supported rutile TiO 2 composites were synthesized for the enhancement of its photocatalytic performance in the degradation of the aqueous terephthalic acid solution under UVC illumination by the increase in its surface area and to simplify its recovery from the treated solution after use. The XRD spectra of the composites revealed the formation of pure rutile TiO 2 on the surface of the clinoptilolite. The SEM images showed the formation of the spherical TiO 2 clusters were composed of nano fibers on the surface of the clinoptilolite. For all composites synthesized, the dispersion of the TiO 2 particles on the clinoptilolite led to a surface area larger than that of the bare TiO 2 and clinoptilolite. The materials synthesized in the present study exhibited higher catalytic activity compared with the commercial Degussa P25 and anatase. Among the catalysts synthesized the TiO 2 /clinoptilolite with a weight ratio of 0.5 was found to be the most photoactive catalyst even though it contains a lesser amount of active TiO 2. The kinetic of the reactions for different catalyst was found to be consistent with the pseudofirst order kinetic model. The results of the Langmuir-Hinshelwood model showed the slight contribution of the adsorption on the degradation. The activity of the TiO 2 /clinoptilolite with a weight ratio of 0.5 decreased after repetitive use due to the accumulation of the TPA molecules on the surface of the catalyst.
Ultrasonics Sonochemistry, 2017
Hydrogen evolution via water splitting was investigated over the sonochemically synthesized TiO 2-clinoptilolite photocomposites. To this aim, a series of photocatalysts containing 10wt% titania were prepared by impregnation and solid state dispersion (SSD) methods in the presence and absence of ultrasound irradiation. The samples were characterized by XRD, FESEM, EDX, BET, FTIR, PL and UV-vis techniques and tested for the water splitting. The characterization results indicated that ultrasound irradiation endowed the photocatalysts with uniform morphology, higher surface area and more homogenous dispersion. In addition, the analyses also exhibited less population of particle aggregates, a strong titania-support interaction and lower electron-hole pairs recombination rate. These features were more prominent when ultrasound was employed during SSD method. The TiO 2 /Clinoptilolite photocatalyst prepared by the ultrasound assisted SSD method (TiO 2 /CLT(US)), had more uniform active sites dispersion, high separation efficiency of electron-hole pairs and as a consequence, high surface density of active sites. The highest photocatalytic activity, 569.88 .h µmol/g 2 TiO , was obtained for the TiO 2 /CLT(US) sample which was about 8 times more than that of P-25 as a reference sample. Furthermore, the TiO 2 /CLT(US) photocomposite as optimal photocatalyst showed sufficient reusability, making it a good choice for photocatalytic water splitting applications.
ACS Omega
High-purity (98.8%, TiO 2) rutile nanoparticles were successfully synthesized using ilmenite sand as the initial titanium source. This novel synthesis method was cost-effective and straightforward due to the absence of the traditional gravity, magnetic, electrostatic separation, ball milling, and smelting processes. Synthesized TiO 2 nanoparticles were 99% pure. Also, highly corrosive environmentally hazardous acid leachate generated during the leaching process of ilmenite sand was effectively converted into a highly efficient visible light active photocatalyst. The prepared photocatalyst system consists of anatase-TiO 2 /rutile-TiO 2 /Fe 2 O 3 (TF-800), rutile-TiO 2 /Fe 2 TiO 5 (TFTO-800), and anatase-TiO 2 /Fe 3 O 4 (TF-450) nanocomposites, respectively. The pseudo-second-order adsorption rate of the TF-800 ternary nanocomposite was 0.126 g mg −1 min −1 in dark conditions, and a 0.044 min −1 visible light initial photodegradation rate was exhibited. The TFTO-800 binary nanocomposite adsorbed methylene blue (MB) following pseudo-second-order adsorption (0.224 g mg −1 min −1) in the dark, and the rate constant for photodegradation of MB in visible light was 0.006 min −1. The prepared TF-450 nanocomposite did not display excellent adsorptive and photocatalytic performances throughout the experiment period. The synthesized TF-800 and TFTO-800 were able to degrade 93.1 and 49.8% of a 100 mL, 10 ppm MB dye solution within 180 min, respectively.