Dye photodegradation employing mesoporous organosilicas functionalized with 1,8-naphthalimides as heterogeneous catalysts (original) (raw)
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European Journal of Chemistry, 2013
TiO2) with tailored morphology and tunable band energy have been synthesized successfully via micro emulsion method. The morphology, chemical composition, band gap energy and stability of prepared nanocomposites were investigated by XRD, SEM/EDX, FT-IR, DRS and TGA. While textural parameters such as surface area, pore volume, and pore diameter were evaluated by nitrogen adsorption-desorption isotherms. The prepared nanocomposites were employed for photocatalytic degradation of phenol and dyes (methyl yellow, auramine O, turquoise blue G) under visible light irradiations. The results of photocatalytic degradation and kinetic parameter (Kapp) strongly suggest that 20% SiO2-TiO2 showed remarkable photocatalytic efficiency in comparison to SiO2-TiO2 nanocomposites with high silica contents. These findings proved significantly that 20% SiO2-TiO2 have marked impact on the photocatalytic efficiency due to its high pore volume, more diameter, high availability of anatase TiO2 in nanocomposite and reduced bandgap energy.
Ti-containing mesoporous silica for methylene blue photodegradation
Applied Catalysis A: General, 2011
Photodegradation of methylene blue (MB) on Ti-containing mesoporous silica prepared by microwaveassisted irradiation as a function of Si/Ti molar ratio was studied. The materials were characterized by N 2 adsorption, XRD, UV-vis/DR, and TEM. All solids showed mesoporous textures with high surface areas, relatively small pore size diameters and large pore volume. XRD showed that framework of solids consists of amorphous silica. It was found that the lower the Si/Ti ratio the higher the photocatalytic activity. Under irradiation with a lamp with more photons from visible light the sample with a Si/Ti ratio equal to 10 showed a higher photoactivity than that of a commercial TiO 2 photocatalyst. This result was in agreement with the UV-vis/DR spectra which showed that material with a Si/Ti = 10 has slightly higher energy band gap than that of commercial TiO 2 suggesting that these materials behave as a photoactive semiconductor.
Chemical Engineering Journal, 2011
Thick-walled hexagonally ordered Cobalt and titanium loaded SBA-15 mesoporous photocatalysts were prepared by impregnating the metal precursor solution on the hydrothermally stable support. The catalysts were analyzed using various spectroscopic and diffraction techniques. XRD measurements revealed that Co exists as its spinel structure Co 3 O 4 and Ti is present in the anatase TiO 2 phase. FTIR showed the absorption bands of Co 3 O 4 around 667 and 565 cm −1 . The visible light absorbance of the photocatalytic systems was studied by Diffuse Reflectance Ultraviolet-Visible spectroscopy (UV-vis DRS) measurements. Systems exhibited fairly good performance as photocatalysts for pollutant degradation under visible light. SBA-15 support was helpful in the easy separation of catalysts after the completion of the degradation. In the case of cobalt loaded SBA-15, activity is found to be maximum when the cobalt loading is 40% whereas 50% Ti loaded SBA-15 is found to be the most active among the prepared systems for the degradation of the dye pollutant methylene blue (MB).
Materials, 2018
The photocatalytic degradation of methylene blue (MB) dye has been performed under UV irradiation in aqueous suspension, employing photocatalysts based on Au (1.5 wt %) and AuCu (Au/Cu = 1, 2.0 wt %), and supported on SBA-15-ordered mesoporous silica, with and without titania (Si/Ti = 3), in order to evaluate the versatility of this mesoporous support in this type of reaction of great impact from the environmental point of view. Samples were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), N 2 adsorption-desorption at −196 • C, and X-ray photoelectron spectroscopy (XPS), so as to study their structural, optical, and chemical properties. All the prepared catalysts were found to be active in the test reaction. The bimetallic AuCu-based catalysts attained very high MB degradation values, in particular AuCu/SBA-15 titania-silica sample reached 100% of dye oxidation after the monitored reaction period (120 min).
Zenodo (CERN European Organization for Nuclear Research), 2013
Azo dye acid orange 12 creates environment pollution problems by releasing toxic and potential carcinogenic substance in the aqueous phase. Visible light photocatalytic degradation of' acid orange 12 was carried out by employing heterogeneous photocatalyst methylene blue immobilized resin (MBIR) Dowex 11. Photodegradation efficiency was small when the photolysis was carried out in the absence of MBIR Dow ex 11, and it was also negligible in the absence of UV light. The optimum values of different parameters which influence the degradation of azo dye such as catalyst dose, concentration of dye, pH of the solution, light intensity and radical quencher was systematically studied. The dye solution could be completely decolorized and effectively mineralized, with average removal efficiency larger than 95% for a reaction time 160 min. Photocatalytic degradation of the dyes follows pseudo-first order kinetics. C0 2 and 11 2 0 are obtained of simple mineralize products.
Microporous and Mesoporous Materials, 2017
Mesoporous silica, SBA-15, decorated with different amounts of TiO 2 (anatase) were prepared by a sol-gel method followed by hydrothermal treatment and calcination, in the presence of a soft template, copolymer Pluronic 123. Tetraethyl orthosilicate (TEOS) was used as the SiO 2 precursor and commercially available TiO 2 anatase nanoparticles as the supported photocatalyst. The materials were characterized by transmission electron microscopy (TEM), energy dispersive X-ray analysis (EDS), N 2 adsorptiondesorption isotherms, raman spectroscopy, ground state diffuse reflectance (GSDR), laser induced luminescence (LIL) and X-ray photoelectron spectroscopy (XPS). The zeta potentials of the pure SBA-15, TiO 2 /SBA-15 substrate and the commercial anatase sample were monitored through a complete range of pH values. All the nanomaterials developed in this work were studied in terms of their photoactivity in the UV range and in the visible range, separately. In the first case, hydroxyl radicals (OH) were confirmed to be the key active oxidizers in the photodegradation of the pesticide amicarbazone in aqueous medium. On the other hand, in the visible range, and following a dye sensitization process via a fluorescent rhodamine-like dye, two different mechanisms could be identified for the formation of the superoxide radical anion, O 2 À .
ES Materials & Manufacturing, 2022
A special sol-gel method is used to successfully synthesize spherical TiO 2 /SiO 2 nanoparticles from titanium tetra-isopropoxide and tetraethoxysilane precursors. The prepared samples were dried at 110 °C and calcined at 300 °C, 500 °C and 800 °C. The formed titanium oxide is in a tetragonal structure with significant pure anatase and rutile phase. The estimated particle size of spherical nanostructure was ~18.40 nm through transmission electron microscopy (TEM) and showed a larger Brunauer Emmett Teller (BET) surface area of 310 m 2 /gm for the sample calcined at 300 o C. The TiO 2 cores are enclosed within SiO 2 particles with an average crystallite size of 10-20 nm. In atomic force microscopy (AFM) images, the same sample displayed the well-structured and macro-pore free morphology. Fourier transform infrared spectroscopy (FT-IR) confirmed the presence of Ti-O-Ti, Si-O-Si and Ti-O-Si metal oxide bond to raise anatase structure of TiO 2. The ultraviolet visible spectroscopy (UV-Vis) of as synthesized samples revels the visible absorption region. Photoluminescence spectroscopy (PL) shows a decrease in emission intensity and the emission band splits into sharp peaks to signify the decrease in recombination rate. These properties predict the materials to photo-degrade organic dyes. The material's photocatalytic activity was evaluated for degradation of methylene blue and methyl orange dyes. It is found that the sample calcined at 300 °C exhibits a better photodegradation for methylene blue (MB, 80-85%) than methyl orange (MO, 70-75%) under mercury light within 2 hours.
Improved stability in SBA-15 mesoporous materials as catalysts for photo-degradation processes
Microporous and Mesoporous Materials, 2016
SBA-15 materials were modified with Cr, Ni and Fe and characterized by ICP, SAXS, XRD, N 2 adsorption, TPR and UVeVis DRS. Their photo-catalytic activity was evaluated for the degradation of Acid Orange 7 (AO7) in aqueous suspensions irradiated by artificial UVeVis light. The results showed that the Crmodified catalyst exhibited the highest activity. The presence of Cr 6þ highly dispersed on the internal surface of the SBA-15 structure would be responsible for this observed behavior. Then, when TiO 2 was loaded on this solid, the photo-activity was increased due to a heterojunction effect between the two metals. Moreover, the TiO 2 cover resulted in the Cr species protection leading to a notable decrease of the Cr leaching into the reaction medium. In addition, comparing with the already reported results for modified MCM-41 catalysts, the solid synthesized here allowed achieving the solution biodegradability in shorter irradiation periods and could be re-used even after four cycles without loss of activity. Thus, the high performance of this material leads to make it a very promising photo-catalyst for pre-treatment of recalcitrant contaminants present in aqueous effluents.
The use of Silica Supported Nickel-Copper Oxide Catalyst for Photodegradation of Methylene Blue
Oriental Journal Of Chemistry
Photodegradation is a save and low cost methods to clean water bodies from some organic pollutants. The method has been developed in term of increasing the efficiency of the degradation capacity of photocatalyst. The photocatalyst working under visible light is the most desirable. The preparation of silica supported nickel-copper oxide [(Ni-Cu)Ox@SiO2] catalyst and the use of the catalyst in the photodegradation of methylene blue in the water are reported. The catalyst was prepared by impregnating the silica support into the mixture of nickel and copper salts, followed by calcination at 800○C for 4 hours. A series method of XRD, SEM-EDX, and UV-Vis Diffuse Reflectance has been used to characterize the catalyst. The catalyst adsorption test was undertaken in the dark, and the catalyst activity test for photodegradation of methylene blue was conducted under the sunlight. The XRD diffractogram of as prepared (Ni-Cu)Ox@SiO2 shows a weak-wide peak at 2θ = 21.8° indicating SiO2 tridymite,...