Parabolic Trough Reactor Research Articles

Development of a sunlight adjustable parabolic trough reactor for 24-hour efficient photocatalytic wastewater treatment

Solar energy is the ideal energy source for activating photocatalysis. However, due to the solar motion, achieving 24-hour solar-powered efficient photocatalytic reactions remains a challenge. In this study, a Sunlight Adjustable Parabolic Trough Reactor (SA-PTR) integrated with flexible parabolic mirror and solar panel was developed. During the daytime, flexible parabolic mirror could be rolled up under sunny condition or expanded under cloudy condition, thus providing optimal light irradiance (1500 W·m−2) and temperature (rises yet below 55 ℃) for photocatalysis. Additionally, the solar panel behind the flexible parabolic mirror could generate solar-electricity. At night, the stored solar-electricity could meet 100 % power demands of UV lamp, enabling a 24-hour solar-powered photocatalytic process. Compared with traditional parabolic trough reactor and inclined plate collector, SA-PTR exhibited higher treatment efficiency against carcinogenic organic dyes (Rhodamine B, Methylene Blue, Methyl Orange), antibiotic (Tetracycline) and pathogenic bacteria (Escherichia coli) during day and night. Moreover, SA-PTR exhibited superior global deployability, economic advantage, safety and lifetime. Therefore, SA-PTR, as a novel solar controllable 24-hour operational photoreactor, is promising to be employed in real wastewater treatment plant.

Synthesis, Characterization, and Photocatalytic Performance of ZnFe2O4-g-C3N4 Composites for Tetracycline Removal from Contaminated Water

The presence of emerging contaminants in wastewater like tetracycline poses a significant challenge in water reuse worldwide. The implementation of a p-n heterojunction and dye-sensitized techniques in the enhancement of graphite carbon nitride provides a promising alternative for visible light-driven degradation of emerging contaminants present in wastewater. The present study investigated dye-sensitized and plain composites in degrading tetracycline using natural sunlight in a parabolic trough reactor. The study synthesized four composites of ZnFe2O4-g-C3N4 at 5, 15, and 25 wt% loading of the ferrite by direct annealing of melamine, followed by thermal and ultrasonic exfoliation of bulk graphite carbon nitride and in situ precipitation with zinc ferrites to yield a composite photocatalyst. The photocatalysts were characterized using X-ray diffraction (XRD) analyses which confirmed that all the spinel ferrite phases of ZnFe2O4 were well bonded with g-C3N4 nanosheets to form a composite. The crystallite sizes were calculated by the Debye–Scherrer equation indicating crystal sizes of between 4.63 and 8.61 nm confirming the nanostructures. The scanning electron microscope-energy dispersive spectroscopy (SEM-EDX) tests verified that the spherical globules of ZnFe2O4 were well attached to the mesoporous layers of g-C3N4 and absence of contaminant phases. The UV-Vis analysis for 25% ZF-GCN revealed a band gap reduction from 2.67 eV to 2.03 eV. The PL intensity for all the composites decreased at excitation of 266 nm and 550 nm which was evidence for suppressed charge recombination. A 25% ferrite loading resulted in the best photocatalytic performance with tetracycline degradation of 93.64% and total organic carbon (TOC) removal of 51.89%. The sensitization of the 25% ZF-GCN composite with Eosin Y further improved its performance for degradation of tetracycline to 94.62% and TOC removal to 68.29%. Therefore, dye sensitization is an efficient way of improving the photocatalytic activity of a multicomponent photocatalyst for the removal of emerging pollutants.

S-scheme heterojunction g-C3N4/TiO2 with enhanced photocatalytic activity for degradation of a binary mixture of cationic dyes using solar parabolic trough reactor

Developing photocatalytic systems by larger design to achieve degradation of dye pollutants by using solar light is highly desirable. Present work is devoted to the synthesis of step-scheme (S-scheme) g-C3N4/TiO2 heterojunction which subsequently employed for simultaneous degradation of a binary mixture of Methylene blue (MB) and Rhodamine B (RhB) solution in parabolic trough collectors (PTC) as continuous flow loop photoreactor. The as-prepared g-C3N4/TiO2 was analyzed by various techniques such as FE-SEM, EDS, XRD, FT-IR, BET, elements mapping and DRS. The composite central design (CCD) was applied to express mathematical relationships among variables such as process time, catalyst mass and initial concentrations of MB and RhB in the degradation process. The photocatalytic activity of the as-prepared composite is higher than pure TiO2 and g-C3N4 that is attributed to the positive synergetic effect of S-scheme between g-C3N4 and TiO2 nanostructure. Under solar irradiation in PTC, g-C3N4/TiO2 was able to degrade about 94.92 and 93.07% of binary mixture MB and RhB, respectively.

A comparative study of the decolorization capacity of the solar-assisted Fenton process using ferrioxalate and Al, Fe-bentonite catalysts in a parabolic trough reactor

Abstract In this work, the decolorization efficiency of Reactive Red 120 (RR120) synthetic solution using ferrioxalate (CuOFeB) and Al, Fe-bentonite (AlFeB) catalysts in the solar-assisted Fenton process was evaluated, as well as impact of H2O2 photolysis on the process efficiency.The photo-Fenton oxidation of dye has been investigated using a concentrating solar parabolic reactor with constant solar radiation of 550 W/m2 and 950 W/m2 for spring and summer periods, respectively. Experimental data has proved that photolysis of hydrogen peroxide has an important role in the process of decolorization, achieving a decolorization efficiency over 80.78% at pH 7. Under the optimal reaction conditions, both catalysts showed a good stability in the processes with dye removal over 90%. The mineralization efficiency depends on the intensity of the solar radiation, wherein ∼50% was achieved under the higher solar intensity. Comparing reaction rate it is important to note that the larger specific surface area of AlFeB (155.83 m2/g) makes him a superior catalyst and thus solar-assisted Fenton process with this catalyst fast and efficient. Based on the decolorization rate constants, the examined processes can be placed in the following order: AlFeB (950 W/m2) > AlFeB (550 W/m2) > CuOFeB (950 W/m2) > CuOFeB (550 W/m2). These findings are confirmed on real effluent, whereby a greater degree of decolorization (91.89%) and mineralization (43%) has been achieved with AlFeB catalyst compared to CuOFeB (30.09% and 15%) during the process.

Green synthesis of TiO2 nanoparticles using leaf extract of Jatropha curcas L. for photocatalytic degradation of tannery wastewater

Green synthesis is a simple, eco-friendly and emerging approach of synthesizing nanoparticles (NPs) and currently, attracting scientific community from around the world. The objective of the present study was to synthesize green titanium dioxide (TiO2) NPs and evaluate its performance for the photocatalytic treatment of TWW after the secondary (biological) treatment process. TiO2 NPs was synthesized using leaf extract of the biodiesel plant, Jatropha curcas L. in a one-step at room temperature to examine its treatability for tannery wastewater (TWW). Moreover, the green synthesized TiO2 NPs was further characterized by UV–Visible spectrophotometer, Field Emission Scanning Electron Microscopy (FESEM), X-ray Energy Dispersive Spectroscopy (EDS), Fourier Transform Infrared (FT-IR) spectroscopy, X-ray Diffraction (XRD), Dynamic Light Scattering (DLS), Brunauer-Emmett-Teller (BET) and Barret-Joyner-Halenda (BJH) analysis. Results confirmed the synthesis and anatase phase of the spherical TiO2 NPs and also unfold the presence of phytochemicals in leaf extract, which might involve in the capping/stabilization of NPs. Further, the green synthesized TiO2 NPs was applied for the first time to testify its potential for the simultaneous removal of chemical oxygen demand (COD) and chromium (Cr) from secondary treated TWW. During the photocatalytic treatment of wastewater in a self-designed and fabricated Parabolic Trough Reactor (PTR), 82.26% removal of COD and 76.48% removal of Cr from TWW was achieved upon the treatment with green synthesize TiO2 NPs, and thus, successfully employed for the wastewater treatment. Overall, the green synthesized TiO2 NPs demonstrated the astounding potential for the in-situ treatment of TWW as an alternative clean-green treatment solution.

Effectiveness of Solar Photo‐Fenton Process for Simultaneous Detoxification of Heavy Metals and Disinfection in Municipal Wastewater by Using Response Surface Method

The goal of this paper was to evaluate the effectiveness of solar photo‐Fenton (Fe2+/H2O2/UV–vis) treatment that is able to degrade heavy metal contents (Cu, Cd, Cr, Fe, Ni, Pb and Zn) and pathogenic microbial population (Fecal Coliform/100 mL) present in municipal wastewater with minimal iron and H2O2 concentrations. Photo‐Fenton experiments were performed in a solar parabolic trough reactor (PTR). Three level factorial design and response surface method (RSM) was used for characterization and optimization of the process in which a response of interest is influenced by four key variables (pH, solar exposure time, catalyst dose (Fe2+/Fe3+), and amount of oxidant (H2O2)). The performance of advanced oxidant process was investigated in terms of percentage degradation of heavy metals and Fecal Coliform (FC) bacteria present in municipal wastewater. The result shows that variables have significant effect on the degradation process of municipal wastewater. Photocatalytic degradation efficiency was found to be dependent on optimized catalyst dose (Fe2+ 100 mg/L) and amount of oxidant (H2O2 500 mg/L). Analysis of variance (ANOVA) exhibited a high coefficient (R2 = 0.72–0.89), thereby indicating a satisfactory fit between the experimental results. The statistical model of solar photo‐Fenton has shown excellent performance. Excessive hydrogen peroxide and iron have shown scavenging effects on hydroxyl radicals and reduced degradation of micro‐pollutants present in wastewater. © 2016 American Institute of Chemical Engineers Environ Prog, 36: 448–459, 2017

Design improvement and performance evaluation of solar photocatalytic reactor for industrial effluent treatment

This work reports the details of the design components and materials used in a linear compound parabolic trough reactor constructed with an aim to use the photocatalyst for solar photocatalytic applications. A compound parabolic trough reactor has been designed and engineered to exploit both UV and visible part of the solar irradiation. The developed compound parabolic trough reactor could receive almost 88% of UV radiation along with a major part of visible radiation. The performance of the reactor has been evaluated in terms of degradation of a probe pollutant using the parameters such as rate constant, residence time and photonic efficiency. An attempt has been made to assess the performance in different ranges of solar spectrum. Finally the developed reactor has been employed for the photocatalytic treatment of a paper mill effluent using Degussa P25 as the photocatalyst. The paper mill effluent collected from Nagaon paper mill, Assam, India has been treated under both batch mode and continuous mode using Degussa P25 photocatalyst under artificial and natural solar radiation, respectively. The photocatalytic degradation kinetics of the paper mill effluent has been determined using the reduction in total organic carbon (TOC) values of the effluent.

Preliminary study on optimization of pH, oxidant and catalyst dose for high COD content: solar parabolic trough collector

In the present study, solar photocatalytic oxidation has been investigated through laboratory experiments as an alternative to conventional secondary treatment for the organic content reduction of high COD wastewater. Experiments have been performed on synthetic high COD wastewater for solar photocatalytic oxidation using a parabolic trough reactor. Parameters affecting the oxidation of organics have been investigated.The experimental design followed the sequence of dark adsorption studies of organics, followed by photolytic studies (in absence of catalyst) and finally photocatalytic studies in presence and absence of additional oxidant (H2O2). All the experimental studies have been performed at pH values of 2, 4, 6,8,10 and the initial pH value of the wastewater (normal pH). For photocatalytic studies, TiO2 has been used as a photocatalyst. Optimization of catalyst dose, pH and H2O2 concentration has been done. Maximum reduction of organic content was observed at the normal pH value of the wastewater (pH = 6.8). The reaction rate was significantly enhanced in presence of hydrogen peroxide. The optimum pH other than the Normal was in the alkaline range. Acidic pH was not found to be favourable for organic content reduction. pH was found to be a dominant factor affecting reaction rate even in presence of H2O2 as an additional oxidant. Also, the solar detoxification process was effective in treating a waste with a COD level of more than 7500 mg/L, which is a otherwise a difficult waste to treat. It can therefore be used as a treatment step in the high organic wastewater treatment during the primary stage also as it effectively reduces the COD content by 86%.

Solar photocatalytic removal of metal ions from industrial wastewater

AbstractThis article describes the photocatalytic reduction and deposition of four metal ions Cr(VI), Ni(II), Zn(II), and Cu(II) present in the wastewater from a chrome plating industry using solar energy irradiated TiO2. A parabolic trough reactor was used to carry out the reaction. Experiments were carried out to find an optimum dose of hole scavenger used (citric acid). The adsorption and reduction of the metal ions at different pH values was also investigated.It was observed that the solar photocatalytic process was effective in removing most of the metal ions in specific reaction conditions. Alkaline pH was found to be more suitable for removal of nickel and zinc. However, Cr(VI) reduced completely even at catalyst concentrations as low as 0.5 mg/L at pH 2. Maximum reaction was completed in the first 4 h of solar exposure. © 2008 American Institute of Chemical Engineers Environ Prog, 2008

Industrial Wastewater Treatment by Photochemical Processes Based on Solar Energy

Background: The solar photo-Fenton process has enormous potential for becoming a viable alternative to conventional processes for the treatment of industrial wastewater. However, the costs associated with the use of artificial irradiation have hindered many times industrial application of these processes. Method of Approach: In this work, the photo-Fenton remediation of various industrial wastewaters (containing silicones, pesticides, phenol and hydrocarbons, model, and real) in aqueous systems has been studied using Fe(II), H2O2, and UV-visible sunlight. Experiments were carried out using a concentrating parabolic trough reactor (PTR) and a nonconcentrating falling-film reactor. Results: In general, at low contaminant concentration, more than 90% of the total organic carbon content could be converted to inorganic carbon within about 2-3h, using sunlight, in reactors of different geometry. Conclusions: Solar light can be used either as an effective complementary or alternative source of photons to the photo-Fenton degradation process of a diversity of chemical pollutants.

Solar Photochemical Degradation of Aminosilicones Contained in Liquid Effluents. Process Studies and Neural Network Modeling

The effectiveness of the solar-driven photo-Fenton process in treating wastewater contaminated with aminosilicone compounds has been evaluated in a parabolic trough reactor under variable weather conditions. On sunny days, after 3 h of irradiation, more than 80% of the initial COD has been removed. The degradation generates compounds that might be readily biodegradable and/or a solid phase that is easily separated by mechanical means. An important interaction between manipulated [H2O2 and Fe(II) concentrations] and nonmanipulated (direct and diffuse components of solar radiation) variables was detected. Therefore, degradation was possible even on cloudy days, provided that the H2O2 and Fe(II) concentrations are conveniently selected. The neural network technique is an effective, simple approach to successfully modeling the solar-driven photo-Fenton degradation. The model might therefore be useful in process optimization, as well as in the design and scale-up of solar reactors for industrial application.

Photo-Fenton degradation of wastewater containing organic compounds in solar reactors

Abstract In this work, the photo-Fenton oxidation of phenol in aqueous solutions has been investigated using Fe 2+ , H 2 O 2 and UV–visible light (sunlight). Laboratory-scale experiments were carried out using solar reactors of two different configurations: (1) a concentrating parabolic trough reactor (PTR) and (2) a non-concentrating thin-film reactor. Global solar irradiance was measured during the experiments. Additional laboratory experiments were carried out in an annular photochemical reactor using an artificial light source, at the same experimental conditions. The results indicate that the photo-Fenton process using solar irradiation is an effective treatment for industrial wastewater containing phenol. At low contaminant concentration (TOC 0 =100 ppm), more than 90% of the total organic carbon content of the initial phenol solution could be converted to inorganic carbon within about 3 h of irradiation, using artificial light or sunlight (even on cloudy days), in reactors of different geometry. At moderate or higher phenol concentrations (TOC 0 =550 or 1000 ppm), the results indicate satisfactory TOC removal (45–55%) at reasonable degradation rates. Experiments under different insolation conditions suggest a direct linear dependence of the organic carbon removal on the accumulated sunlight energy reaching the system. Solar light can be used either as a complementary or alternative source of photons to the process.

A comparison of prototype compound parabolic collector-reactors (CPC) on the road to SOLARDETOX technology

Solar photocatalytic detoxification of non-biodegradable chlorinated hydrocarbon solvents (NBCS) is carried out in different concentrating and non concentrating devices using TiO2 as a photocatalyst fixed on the inner surface of the reaction tubes or as a slurry catalyst which has to be removed from the treated water. The reaction is most effective using 200 mg/l of TiO2 as a slurry in a non concentrating CPC reactor. The concentrating parabolic trough reactor has a poor activity because of its minor irradiated reactor surface. Catalyst coated glass tubes are less efficient then the used slurry catalyst. Their advantage is that no catalyst has not to be removed from the treated water and there is no loss of activity during treatment. Yet their physical stability is not sufficient to be competitive to the slurry catalyst. Nevertheless the degradation results are very promising and will possibly lead to commercial applications of this technology.

New developments using holographic concentration in solar photochemical reactors

This paper presents test results achieving on (20cm×50cm) cylindrical holographic mirrors being recorded in dichromated gelatin for use in solar chemistry applications. The realized spectral reflectivity range 480-620 nm is adapted to the sensitizer Rose Bengal which is the sensitizer frequently used in photo-oxidation reactions. Aluminum mirrors and holographic elements were used as reflecting elements in a lab-scale parabolic trough reactor. The effect of the different elements on the heat transfer into the reaction was compared.

Photocatalytic degradation of ammonia with t102 as photocatalyst in the laboratory and under the use of solar radiation

A laboratory set-up for the photocatalytic degradation of NH 3/NH 4 + was designed. It includes a tube reactor (volume 12.3 ml) and a Xe-lamp (α > 300 nm) as irradiation source. Suspended TiO 2 powder was used as photocatalyst. For the on-line determination of NH 3 a gas-sensing probe was shown to be useful down to the lower mg/l level (detection limit: 2.2 10 −6 mol/l). After optimization a breakdown of NH 3/NH 4 + at the 5 10 −4 mol/l level for up to 70 % after 6 h if irradiation could be realized. The influence of the pH, the TiO 2 concentration, the temperature and the flow rate on the degradation of NH 3/NH 4 + was examined. The anionic degradation products, which were found to occur beside the N 2 itself, were determined by single column ion chromatography (SCIC). As a function of the pH and the concentration of TiO 2 variable concentrations of NO 2 − and N0 3 − were found (optimum: 9.9 % and 19.0 % of the decomposed NH 3/NH 4 + or 4.0 and 7.3 % of the NH 3/NH 4 + originally present). Experiments with solar radiation were carried out in a parabolic trough reactor at pilot plant-scale and were found to give degradation rates and reaction products similar to those obtained with the laboratory set-up.