Photodegradation of Rhodamine B over unexcited semiconductor compounds of BiOCl and BiOBr (original) (raw)
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The interfacial adsorption process and the white-light-induced photo-sensitized degradation of different rhodamine dyes (rhodamine B, rhodamine 6G, and rhodamine 101) on the wide-band-gap semiconductor BiOCl have been investigated. Adsorption of all the rhodamine molecules on BiOCl is an exothermic process and the saturated adsorption capacities were best deduced by Langmuir model fitting. By using quantum chemical calculations (Gaussian 03 software), the relationship between the frontier orbital energy of the dye molecules and the rate of photodegradation was also established. The calculated absolute value of E LUMO was found to increase in the order Rh 101 \ Rh 6G \ RhB, which was similar to the trend of photodegradation reaction kinetics rate fitted by use of the pseudo-zero-order kinetics model.
Bulletin of Materials Science, 2019
In this study, a low temperature precipitation method was applied to prepare BiOX (X = Cl, Br and I) nanostructures using HCl, HBr and HI as halogen sources. The as-prepared samples were characterized by various techniques such as X-ray diffraction, field emission scanning electron microscopy, energy dispersive spectroscopy, Fourier-transform infrared spectroscopy, diffuse reflectance spectroscopy and nitrogen adsorption-desorption analysis. The photoactivity of BiOX samples to degrade rhodamine B (RhB) molecules in aqueous solution was investigated under white LED irradiation. The results indicated that BiOCl exhibits a higher photodegradation performance in comparison with BiOBr and BiOI. Ninety six percent of the RhB molecules was degraded over BiOCl after 25 min light irradiation, whereas under the same conditions, the degradation efficiencies of BiOBr and BiOI samples are 62 and 24%, respectively. The enhanced photodegradation activity of BiOCl is ascribed to the higher specific surface area which increases the physical adsorption of RhB molecules on the photocatalyst surface. Moreover, the photodegradation mechanism and the main radical species in the degradation reactions over BiOCl were investigated.
BiOBr was investigated as an efficient catalyst for the photosensitized degradation of Rhodamine B (RhB) dye using 450 nm monochromatic light as a source of excitation. It was found that RhB molecules can be decomposed via a photosensitized process more efficiently on the un-excited BiOBr semiconductor (E g = 2.8 eV) and the reaction follows apparent zeroth order kinetics. The effects of catalyst dosage and reaction temperature on the photodegradation efficiency as well as the photostability of as-prepared BiOBr have been investigated. Around 85 % removal efficiency was achieved using 0.4 mg/mL of BiOBr at room temperature (300 K). A possible photodegradation mechanism has been also proposed and discussed based on the experimental results achieved in this study.
Industrial & Engineering Chemistry Research, 2012
The interfacial adsorption process and the white-light-induced photosensitized degradation of different rhodamine dyes (rhodamine B, rhodamine 6G, and rhodamine 101) on the wide-band-gap semiconductor BiOCl have been investigated. Adsorption of all the rhodamine molecules on BiOCl is an exothermic process and the saturated adsorption capacities were best deduced by Langmuir model fitting. By using quantum chemical calculations (Gaussian 03 software), the relationship between the frontier orbital energy of the dye molecules and the rate of photodegradation was also established. The calculated absolute value of E LUMO was found to increase in the order Rh 101 \ Rh 6G \ RhB, which was similar to the trend of photodegradation reaction kinetics rate fitted by use of the pseudo-zeroorder kinetics model.
Journal of Environmental Sciences, 2007
The photocatalytic degradation of dye Rhodamine B (RhB) in the presence of TiO 2 nanostripe or P25 under visible light irradiation was investigated. The degradation intermediates were identified using Infrared spectra (IR spectra), 1 H nuclear magnetic resonance ( 1 HNMR) spectra, and gas chromatography-mass spectroscopy (GC-MS). The IR and the 1 HNMR results showed that the large conjugated chromophore structure of RhB was efficiently destroyed under visible light irradiation in both the photocatalytic systems (TiO 2 nanostripe or P25 and Rhodamine B systems). GC-MS results showed that the main identified intermediates were ethanediotic acid, 1,2-benzenedicarboxylic acid, 4-hydroxy benzoic acid and benzoic acid, which were almost the same in the TiO 2 nanostripes and P25 systems. This work provides a good insight into the reaction pathway(s) for the TiO 2 -assisted photocatalytic degradation of dye pollutants under visible light irradiation.
The adsorption (under dark condition) and photodegradation behaviors of Rhodamine B molecules on BiOBr under visible (532 nm) pulsed laser exposure were studied and reported for the first time. The adsorption kinetics/isotherm behaviors and thermodynamic process (adsorption dynamical parameters) occurred on as-prepared BiOBr were investigated. The photodegradation mechanisms, effects of BiOBr dosage and pulsed laser energy on dye removal efficiency in the presence of BiOBr particles were studied as well. Furthermore, the photodegradation of other kinds of Rhodamine dyes such as Rhodamine 6G, Sulforhodamine B and Sulforhodamine 640 were initially investigated and compared under 532 nm pulsed laser exposure. The study also demonstrated that the dissolved oxygen plays a very significant role in the photo-catalytic decomposition of Rhodamine. The BiOBr catalyst was found intact even under acidified conditions showing good stability of the catalyst.
Photocatalytic materials and additional components, especially promoters, play a pivotal role in the success of photocatalysed environmental remediation processes. To understand the influence of acid promoters in the absence and presence of surfactants, photocatalytic degradation of a model dye rhodamine B (RhB) was studied by UV-photocatalysis (254 nm UV source) with the subsequent addition of each of 0.01 mol dm− 3 of nitric acid (HNO3), sulphuric acid (H2SO4), hydrochloric (HCl), citric acid and acetic acid. Furthermore, the effect of 0.01 mol dm− 3 of sodium hydroxide (NaOH) and sodium carbonate (Na2CO3), as well as surfactants, including the cationic cetrimonium bromide (CTAB), anionic sodium dodecylsulphate (SDS) and non-ionic surfactant tween 80, were analyzed using a UV–Visible spectrophotometer. The kobs. values for photodegradation of RhB under UV-irradiation was heavily dependent on type of acid and base. Pre-micellar, micellar and post-micellar concentrations of surfactants were also analyzed for their effects on the photodegradation of RhB. Concentrations at and above the critical micelle concentration (CMC) were found to suppress the photocatalytic degradation of RhB in the presence of a promoter (HNO3). Micellar solubilization is responsible for the changes in the photocatalytic activity. Nonionic micelles are unable to protect the dye over longer times due to autooxidation process. The resulting degradation products of RhB by radical dotOH were identified by LC-MS and GC–MS analysis and accordingly a schematic degradation pathway was proposed.
Journal CleanWAS, 2020
Rhodamine B (RhB) is widely employed in dyeing in textile, paper, paints and leather industry. The wastewater containing RhB dye can cause serious environmental and biological problems. Hence, the remediation of RhB treatment is necessary for the environment. In this study, the photodegradation of RhB in water under sunlight irradiation with dye-sensitized titanium dioxide (TiO2) is investigated. The influence of various conditions, such as TiO2 dosages, initial RhB concentration, temperature, pH, sunlight intensity and irradiation time on the photodegradation of RhB are also studied. About 96% of RhB is photodegraded within 20 min under the optimized conditions. Therefore, the photodegradation treatment for the wastewater including RhB under sunlight is very simple, easy and low cost technique.
Bismuth oxybromide (BiOBr) has attracted a resurgence of interest due to the outstanding visible light driven photocatalytic performance, which has been widely reported. However, its photosensitization degradation performance of methyl orange (MO) is limited possibly caused by low negative LUMO (lowest unoccupied molecular orbitals) level of MO molecules. The work presented here deals with the improved photodegradation behavior of methyl orange molecules onto BiOBr in the presence of Rhodamine B (RhB, as photosensitizer) through a semiconductor-mediated process. It was found that MO could be photodecomposed much effectively under the assistance of RhB molecules from aqueous solution. The photosensitization process which occurred between RhB and BiOBr is of photochemical origin and responsible for the boosted photodegradation behavior towards MO, which strongly depends on the irradiation time, BiOBr dosage and concentration of model contaminant (MO) and photosensitizer (RhB). Gaussian 03 program, frontier orbital energy Graphical abstract: Schematic diagram of possible mechanism behind the enhanced photodegradation of MO over BiOBr in the presence of RhB driven by visible light.