Novel Solar Photocatalytic Reactor for Wastewater Treatment (original) (raw)
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Sustainable Environment Research, 2017
The purpose of this work is to design a prototype of a flat-panel (FP) photoreactor for wastewater treatment via solar illumination using TiO 2 nano-photocatalysts. The TiO 2 nanoparticles are initially coated on transparent plastic granules to avoid the difficulties associated with the recovery of nanoparticles after completing the treatment process. The coated granules were distributed in the space inside the reactor panel. The upper cover of the reactor is a transparent material that allows light penetration to activate the catalyst. Wastewater is circulated into the spaces between the coated granules. When exposed to solar illumination, photocatalytic reactions occur on nearly the entire surface of the coated granules. To test the reactor viability, we used technical grade TiO 2 (for affordability) and a solution of Methylene Blue (MB) as a sample of wastewater. The photoreactor was tested for treating 30 L of MB solution with an initial concentration of 25 mg L-1. We observed that the reactor was able to degrade more than 98% of the MB in the solution after 48 h of solar illumination. The performance of the FP photoreactor was also improved by arranging several reactor panels in series. Using four panels, we observed that the complete decomposition of the same MB solution can be achieved within 10 h. The proposed FP photoreactor is a very promising alternative for use in decomposing recalcitrant organic pollutants in wastewater.
Engineering Development of a Photocatalytic Reactor for Waste Water Treatment
Process Safety and Environmental Protection, 2005
A simple design of photocatalytic reactor is proposed based on a study of the use of a suspension of relatively large titanium dioxide catalyst particles (ca. 10 to 100 mm) which can be separated from treated waste water using a hydrocyclone. Upward flow of suspension through an array of ultraviolet lamps and cooling tubes positioned horizontally is recommended. Flow rate is determined by residence time requirements to suit the kinetics. This design can be easily scaled up in modular form. The absorption or extinction of light of appropriate wavelengths by glass, water, pollutant and catalyst particles of different sizes at various concentrations has been measured to allow determination of catalyst concentration and suspension thickness required to obtain near total extinction of light. A rate equation is proposed which shows the part played by the very many factors involved and provides a new and coherent view of the complex interactions of the variables. The reactor design methodology is given.
Treatment of Industrial Wastewater by Solar Nano Photocatalysis
International Journal of ChemTech Research, 2015
Experimental investigations were carried out to find environmental friendly and effective solution by harnessing of solar energy through photocatalysis to degrade the contaminants present in wastewater using ZnO nano particles as photocatalyst . Multilayer thin film of photocatalyst (ZnO) was developed inside the glass tube reactor by layer-by-layer (L-b-L) method. Effluent samples were collected from four industries in the sultanate of Oman and a series of experiments were carried out in a ZnO thin film coated reactor under solar radiation exposure for 4 hours. pH, COD, TOC , TDS and Turbidity was analyzed for the samples collected on hourly basis and a comparison of treatment showed substantial degradation of pollutants in all the wastewater samples and also complete de-colorization of sewage wastewater.
Journal of Chemical Technology & Biotechnology, 2020
The research in the heterogeneous photocatalysis to remove different type of pollutants in liquid phase notably increased in the last years. The main objectives of the researches dealing with photocatalysis were: i) to shift the photoactivity of catalysts in the visible light range or to increase the degradation rate; ii) the use of the artificial light sources (low pressure lamp, high pressure lamp, LEDs and optical fibers) and solar light; iii) photocatalysts recovering and deactivation; iv) photoreactor configuration; v) photodegradation of contaminants of emerging concern, iv) verification of induced effects from the photocatalytic treatment, such as the induction of bacterial resistance. Here, one of the main problems of practical application of photocatalysis, which is to develop a methodology for the photoreactors scale-up, is addressed considering the use of mathematical modeling. In this perspective, this mini review reports a literature exam of the main parameters that is important to take into account for the design and the developing of photoreactors for wastewater treatment, also through the use of computational fluid dynamics models (CFD).
International Journal of Chemical Reactor Engineering, 2014
In this study, a highly polluted wastewater from tannery industry is treated by photocatalysis using home-made N-doped TiO2 as catalyst. The doping by nitrogen of titania particles leads to a reduction in the absorption threshold from 3.2 to 2.5 eV, permitting the absorption of radiation characterized by a wavelength in the visible spectrum.Experiments were carried out by using different light sources, in particular white LEDs, blue LEDs, and UV lamps, with the aim to evaluate the process efficiency at different operating conditions. The obtained performances were compared with those using an undoped commercial TiO2 catalyst (Degussa P25).Moreover, a simplified mathematical model capable to correlate the power input of the used light sources, the geometrical properties of the reactor, and emitting sources spectra with the performances of the photocatalytic reaction was developed.
2017
The solar photocatalytic oxidation of potassium hydrogen phthalate (KHP) was examined in a batch reactor as a model. Catalyst load, initial KHP concentration and pH are variables studied in this research. The kinetics model for the reaction was investigated in this study. The nano particle of TiO2 (P25) used as catalyst for this reaction. The results revealed that the optimum catalyst load in the batch reactor is 1g/L of TiO2 The removal efficiency of the organic compounds reduces as the initial concentration increases, with a first order reaction rate at high concentration and zero order reaction rate at low concentrations were noticed in the study. The zero order at low concentrations reaction has a rate constant of 23.53 mg L -1 h -1 , while high concentrations the first order has a rate constant of 0.6225 h 1. The photocatalytic oxidation is dependent on pH and, it increases with the increasing of pH. Treatment of secondary treated wastewater results in about 50% removal of orga...
Catalysts, 2016
For the last four decades, viability of photocatalytic degradation of organic compounds in water streams has been demonstrated. Different configurations for solar TiO 2 photocatalytic reactors have been used, however pilot and demonstration plants are still countable. Degradation efficiency reported as a function of treatment time does not answer the question: which of these reactor configurations is the most suitable for photocatalytic process and optimum for scale-up and commercialization? Degradation efficiency expressed as a function of the reactor throughput and ease of catalyst removal from treated effluent are used for comparing performance of different reactor configurations to select the optimum for scale-up. Comparison included parabolic trough, flat plate, double skin sheet, shallow ponds, shallow tanks, thin-film fixed-bed, thin film cascade, step, compound parabolic concentrators, fountain, slurry bubble column, pebble bed and packed bed reactors. Degradation efficiency as a function of system throughput is a powerful indicator for comparing the performance of photocatalytic reactors of different types and geometries, at different development scales. Shallow ponds, shallow tanks and fountain reactors have the potential of meeting all the process requirements and a relatively high throughput are suitable for developing into continuous industrial-scale treatment units given that an efficient immobilized or supported photocatalyst is used.
Applied Catalysis B: Environmental, 2011
This article reports on degradation using TiO 2 immobilized on glass spheres of 15 emerging contaminants (ECs) at low concentrations in simulated and real Municipal Wastewater Treatment Plant (MWTP) effluents. A sol containing titanium isopropoxide, commercial P25 and polyethylene glycol (PEG) was prepared, and a layer of the photoactive precursor was immobilized on glass spheres by dip-coating. The raw materials and the xerogels were characterized by N 2 adsorption/desorption, XRD and TGA-DTA. The xerogel showed the TiO 2 anatase, rutile and brookite crystal phases characteristic of the reference materials. The diffraction pattern showed no modification of the crystal size from incorporation of the PEG. Two different TiO 2 anatase crystal sizes were identified, which was attributed to the different TiO 2 precursors used in the synthesis route. Degradation of the emerging contaminants (acetaminophen, antipyrine, atrazine, carbamazepine, diclofenac, flumequine, hydroxybiphenyl, ibuprofen, isoproturon, ketorolac, ofloxacin, progesterone, sulfamethoxazole and triclosan), at an initial concentration of 100 g L −1 each was determined by ultra-performance liquid chromatography (UPLC-UV) and mineralization was monitored by measuring the dissolved organic carbon (DOC). The experiments were performed in a pilot compound parabolic collector (CPC) solar plant at the Plataforma Solar of Almeria (Spain). 85% of the compounds were degraded within 120 min of illumination time depending on the water. The results show the potential application of this technology as a good alternative to suspension systems for the treatment of polluted water.
Photocatalytic Degradation of a Chemical Industry Wastewater: Search for Higher Efficiency
2017
15 Páginas, 8 Figuras, 3 TablasIn the present research, an annular photocatalytic reactor system was designed and operated to quantify the degradation of a real case chemical company wastewater. The photocatalytic degradation process was analyzed and optimized varying some critical operating variables such as pH, catalyst (TiO2) loading, H2O2 concentration (oxidant agent) and light intensity to find the best criterion warranting a high level of degradation. It was demonstrated that a pH of 7.0 and an amount of 2.0 g/L ofTiO2 resulted in a cleanup allowable level for discharge to river. Furthermore, photo-degradation by H2O2/TiO2/UV process was much more efficient (97%) with respect to the processes carried out individually by H2O2/UV(92%) orTiO2/UV (89%). It is remarkable that the optimum concentration of H2O2 was 11.6mM, and increasing the intensity of light accelerated degradation reaction. Careful selection of industrial wastewater reflected the capability predicting the level of...
Catalysts
In the present study, methylene blue (MB) removal from aqueous solutions via the photocatalytic process using TiO2 as a catalyst in the presence of external ultra-violet light (UV) was investigated. The results of adsorption in the absence of UV radiation showed that adsorption reached an equilibrium state at 60 min. The experimental kinetic data were found to be well fitted by the pseudo-second-order model. Furthermore, the isotherm study suggested that dye uptake by TiO2 is a chemisorption process with a maximum retention capacity of 34.0 mg/g. The photodegradation of MB was then assessed under various experimental conditions. The related data showed that dye mineralization decreased when dye concentrations were increased and was favored at high pH values and low salt concentrations. The simultaneous presence of organic and inorganic pollution (Zinc) was also evaluated. The effect of the molar ratio Zn2+/MB+ in the solution at different pH values and NaCl concentrations was also m...