Methyl Orange Solution Research Articles

Effect of Sr-Doping on the Photocatalytic Performance of LaNiO3−σ

In this study, to investigate how oxygen vacancy impacts the photocatalytic performance of LaNiO3, undoped and Sr-doped LaNiO3−σ nanoparticles are successfully prepared by the sol-gel method. The X-ray diffractometer (XRD) results show both two samples belong to the R-3c space group of the rhombohedral system. According to the conservation of valence and the X-ray photoelectron spectroscopy (XPS) results, it is demonstrated that Sr-doping can introduce more oxygen vacancy into LaNiO3−σ. According to photocatalytic experiments of the degradation of methyl orange (MO) solution, La0.875Sr0.125NiO3−σ shows higher photocatalytic performance than undoped LaNiO3−σ. First-principle calculation results show that the introduction of oxygen vacancy and Sr-doping can lead to the narrowing of the band gap width of LaNiO3.

DEVELOPMENT AND TESTING OF A SYSTEM FOR FORMING NEUTRON FLUXES ON A LINEAR ELECTRON ACCELERATOR

A system for the formation of neutron fluxes, consisting of a neutron converter, a neutron reflector and a lead protection, has been developed and partially manufactured. Test tubes with an aqueous solution of the organic dye methyl orange with the addition of 4% boric acid were used as detectors of the generated neutron fluxes, which is associated with the impossibility of using gas-discharge neutron counters in the accelerator bunker due to the impact of pulsed electrical noise and gamma-ray flashes. Testing of the neutron flux formation system showed that the neutron flux at the location of the detectors increased by 15%, while the neutron background in the accelerator bunker decreased by 3 times. The conducted studies have shown the effectiveness of using a chemical dosimeter under conditions of intense pulsed neutron fluxes.

A Novel Shift in the Absorbance Maxima of Methyl Orange with Calcination Temperature of Green Tin Dioxide Nanoparticle-Induced Photocatalytic Activity

Background: The photocatalytic degradation of toxic organic compounds has received great attention for the past several years. Dyes, such as methyl orange (MO), are one of the major pollutants which create environmental hazards in the hydrosphere, living organisms and human beings. During photocatalytic degradation, NPs are activated in the presence of UV–Vis radiation which in turn creates a redox environment in the system and behaves as a sensitizer for light-induced redox mechanisms. Tin oxide (SnO2) is one of the prominent, but less investigated, nanomaterials compared to titanium oxide (TiO2) and Zinc oxide (ZnO) nanoparticles (NPs). Methods: Herein, Buxus wallichiana (B. wallichiana) leaf extract was utilized as a reducing and capping agent for the biosynthesis of SnO2 NPs. The effects of the calcination temperature on their photocatalytic, structure and surface properties were then examined. The degree of crystallinity and the crystallite size were determined through X-ray diffraction (XRD) analysis. The pore size and surface area were calculated by Burnett–Emmitt–Teller (BET) and Barrett–Joyner–Halenda (BJH) methods based on nitrogen desorption data. Morphological changes were assessed by scanning electron microscopy (SEM). The optical behavior was analyzed through UV–Vis diffuse reflectance spectroscopy (DRS) data and the band gap subsequently calculated. The photocatalytic efficiency of SnO2 NPs was evaluated by double beam UV–Vis spectrophotometry under the influence of initial MO concentration, catalyst dose and pH of MO solution. The surface functional moieties were identified using Fourier transform infrared (FTIR) spectroscopy. All the calcined SnO2 NPs were used as photocatalysts for the mineralization of MO in aqueous media. Results: The degree of crystallinity and the crystallite size increased with the calcination temperature. The transmittance edge obtained for all the calcined SnO2 NPs shows a maximum absorbance in the visible range (λ-max = 464 nm). Moving toward higher wavelengths, a sudden intense red shift (from 464 nm to 500 nm), attributed to the incorporation of a hydroxyl radical at the ortho-position in the benzene ring associated with the dimethylamine group of MO, was observed in the absorbance of the samples calcined up to 300 °C. The percentage degradation of MO was found to decrease with increasing calcination temperatures. The optimal photocatalytic activity toward MO (15 ppm) in a solution of pH = 6 was obtained with 15 mg SnO2 NPs calcined at 100 °C. Conclusions: UV–Vis absorption spectroscopy demonstrates that the absorption spectra of MO are strongly modified by the calcination temperature. This work opens new avenues for the use of SnO2 NPs as photocatalysts against the degradation of industrial effluents enriched with different dyes.

Titanium Dioxide–Reduced Graphene Oxide Composites for Photocatalytic Degradation of Dyes in Water

Dye wastewater due to industrialization, urbanization and academic activities has become one of the most important environmental issues today. Photocatalytic degradation technology is considered as a promising technology for treating dye wastewater due to its advantages of environmental protection and low energy consumption. Herein, titanium dioxide–reduced graphene oxide composites (TiO2-RGO) were prepared by a one-step hydrothermal method to degrade different dyes (methyl orange, methylene blue and rhodamine B) in water. The structure and morphology of TiO2-RGO were characterized using various technical approaches. The degradation effect of TiO2-RGO on the dye was in accordance with a first-order kinetic reaction. The degradation rate of TiO2-6%RGO for methyl orange at 15 min was 1.67 times higher than that of TiO2, due to the strong electron transport ability and excellent adsorption properties of graphene. TiO2-6%RGO has better degradation performance for fluorescent dyes and anionic azo dyes. Notably, the degradation rate of methyl orange by TiO2-6%RGO photocatalysis for 90 min could reach 96.9%. Meanwhile, the TiO2-6%RGO showed excellent reusability, as the initial degradation rate of 93.2% was maintained after five degradation cycles of methyl orange solution. The present work provides a universal strategy for designing efficient photocatalytic materials.

Preparation of reusable UHMWPE/TiO2 photocatalytic microporous membrane reactors for efficient degradation of organic pollutants in water

A photocatalytic membrane reactor is an effective method to degrade organic pollutants in water and air. This method has many advantages, such as a complete degradation of organic pollutants, no secondary pollution to the environment, environmental protection, and high efficiency. Thus, how to efficiently manufacture membrane reactors with high catalytic efficiency is essential. In this study, ultra-high molecular weight polyethylene (UHMWPE)/inorganic particle photocatalytic microporous membrane reactors with high porosity and high loading capacity were prepared using a melt-blending method. In the preparation process, UHMWPE, liquid paraffin (LP), and nanoparticles, which acted as a binder, porogen, and photocatalyst, respectively, were completely dispersed and mixed in a self-developed pulsating tensile stress mixer. Then, the LP was extracted to obtain a microporous membrane reactor with high porosity and high loading of inorganic particles. This reactor had the advantages of excellent catalytic efficiency, industrial manufacture and application, recyclable and reusable, and environmental protection. In this study, inorganic titanium dioxide (TiO2) nanoparticles were used as photocatalysts to prepare the microporous membrane reactor. The effects of the ratios of UHMWPE to LP, the contents and sizes of inorganic particles, the thickness of the membrane, and biaxial tension treatment on the structure of the membrane reactors and the catalytic efficiency of organic dyes and hormone pollutants in water were studied. Results showed that the photocatalytic microporous membrane reactor with 75% porosity and 80 wt% of TiO2 had the best photocatalytic performance. Under ultraviolet photocatalysis, the degradation rate of the 20-mg/L methyl orange solution reached 98.5% within 60 min. Moreover, the degradation rate of the methylene blue solution reached 98.4% within 60 min, and that of the 20-mg/L Congo red solution reached 100% within 40 min. Furthermore, the degradation rate of the 50-mg/L tetracycline hydrochloride solution exceeded 96.6% within 80 min.

Adsorption performance and mechanism of methyl orange by layered zinc hydroxide nitrate improved through flame spray pyrolysis method

To adsorb methyl orange (MO) pollutant in wastewater, zinc hydroxide nitrate (ZHN) was synthesized by commonly-used chemical coprecipitation method (CCM) and the flame spray pyrolysis (FSP) method in this work. ZHN can efficiently adsorb MO pollutant. Specially, the adsorption capacity per unit mass of ZHN synthesized by FSP and CCM can reach 732.72 mg/g and 611.76 mg/g. ZHN synthesized by FSP possesses faster initial adsorption rate, larger adsorption capacity per unit mass and better adsorption characteristics for MO solution which may be due to the more voids between the lamellar of ZHN synthesized by FSP and the fact that the grain size, lamina thickness, and specific surface area of ZHN synthesized by FSP are 1/2, 1/6 and 4 times of those of ZHN synthesized by CCM, respectively. The adsorption kinetics of ZHN on MO is conformed to the pseudo-second-order kinetic equations. Moreover, at a low equilibrium concentration of MO, the adsorption behavior of ZHN is closer to the monolayer surface adsorption. When the adsorption on the ZHN surface tends gradually to the saturation with the increase of the equilibrium concentration, it will show the characteristics of interlayer adsorption.

Foam-gelcasting preparation and properties of high-strength mullite porous ceramics

The unique structure and excellent properties of porous materials enhance their prospects for application as catalyst supports, thermal insulation, and liquid filtration, and within biomedicine. In this study, mullite porous ceramics with high apparent porosity were successfully prepared using non-toxic and economical poly-γ-glutamic acid (γ-PGA) gelling system using the foaming method. The effects of the foaming agent (sodium dodecyl sulfate) and sintering temperature on the microstructure, apparent porosity, and mechanical properties of mullite porous ceramics were reported for the first time. The prepared mullite porous ceramics exhibited excellent properties with a porosity of up to 80.23%, corresponding to a bulk density and thermal conductivity of 0.62 g/cm3 and 0.17 W/(m·K), respectively. Moreover, the mullite porous ceramics contained significant amounts of unique near-spherical pores that contributed to a significant increase in compressive strength (6.1 MPa). In addition, the potential use of mullite porous ceramics as catalyst supports was validated by photodegradation of methyl orange solution.

Carboxylated-covalent organic frameworks and chitosan assembled membranes for precise and efficient dye separation

Covalent organic frameworks (COFs) based membranes have demonstrated great potentials in molecular separation. Currently, most studies focus on developing continuous COF membranes. However, their low crystallinity compared with COF powders due to the more restricted synthesis conditions impedes their application in precise separation. Herein, we explored the assembly of highly crystalline COF powders with chitosan (CS) to construct precise-sieving membranes with high COFs loading. A post-carboxylated COFs (TATP-COOH) was synthesized, and a facile and scalable strategy was developed for constructing the assembled COF membranes (TATP-COOH@CS/TATP-COOH/CA) with TATP-COOH loading as high as 40 wt% (82 v%). Characterizations revealed TATP-COOH particles could interact with CS via H-bonding to form dense TATP-COOH@CS layers, and the TATP-COOH layer on the CA substrate was essential to obtain mechanically stable membranes. The prepared membranes exhibited precise rejection to Congo red, Coomassie brilliant blue (BB), Alcian blue and Direct blue 19 with 100% rejection and ultrafast permeance (>1350 L m−2 h−1 MPa−1). It also showed superior precision in separating Methyl orange and BB mixed solution with only Methyl orange passing through. This study provides a significant concept and a facile strategy to the preparation of high precise-sieving COF membranes to take advantages of highly crystalline COFs.

Formulation of Bismuth (Bi2O3) and Cerium Oxides (CeO2) Nanosheets for Boosted Visible Light Degradation of Methyl Orange and Methylene Blue Dyes in Water

Annealing of periodic mesoporous organosilica supported with bismuth (Bi@PMOS) and cerium (Ce@PMOS) nanoparticles was carried out to derive bismuth oxide (Bi2O3) and cerium oxide (CeO2) nanosheets. The hydrothermal sol-gel method was used to synthesize hexagonal Bi@PMOS and Ce@PMOS. These PMOS provided an opportunity for bismuth and cerium to retain a hexagonal configuration alongside their traditional crystalline phases (tetragonal and cubic) in Bi2O3 and CeO2 nanosheets. All produced materials were found to be dynamic under sunlight irradiation for the degradation of methylene blue (MB) and methyl orange (MO). However, the Bi2O3 and CeO2 nanosheets showed better potential and photo-catalytic performances than Bi@PMOS and Ce@PMOS due to the presence of the unique blend of crystalline phases. The synthesized Bi@PMOS, Ce@PMOS, Bi2O3, and CeO2 were structurally characterized by FTIR and XRD techniques. These showed characteristic vibrations of successfully loaded bismuth and cerium with hexagonal symmetry. EDX results confirmed the elemental detection of bismuth and cerium, while SEM images revealed the nanosheets in the synthesized materials. The optical response and detection of reactive species were carried out by photoluminescence (PL) and showed emissions at 700 nm. The PL data were also used to calculate band gaps of 3.72, 3.70, 3.35, and 2.88 eV for Ce@PMOS, Bi@PMOS, CeO2, and Bi2O3, respectively. A UV/visible spectrophotometer scanned the photocatalytic competences of the synthesized nanomaterials through the degradation of MB and MO dyes. Then, 10 mg of Bi@PMOS and Ce@PMOS degraded 15 mg and 8.4 mg of MB and 10.8 mg and 8 mg of MO, respectively, in 20 mg/L solutions. However, equivalent quantities of Bi2O3 and CeO2 (10 mg of each) exhibited more efficient photocatalysis of the 20 mg/L solutions of MB and MO, degrading 18.4 mg and 15.4 mg, and 12.4 mg and 17 mg, respectively, in only 1 h. The Bi2O3 and CeO2 photocatalysts were regenerated and their photodegradation results were also recovered. Bi2O3 and CeO2 showed only 10% and 8% (for MB), and 8% and 10% (for MO) decline in catalytic efficiency, respectively, even after four consecutive recycles. These results demonstrate that these materials are dynamic, long-lasting photocatalysts for the rapid degradation of azo dyes in contaminated water.

Photocatalytic Activity and Mechanism of Cu2+ Doped ZnO Nanomaterials

The photocatalytic activity and mechanism of photocatalysts made of ZnO nanoparticles before and after doping with different Cu2+ concentrations were studied by electron paramagnetic resonance and X-ray diffraction. The nanoparticles were prepared using sol–gel method. UV-vis spectrometers characterized the photocatalytic degradation effect of the composite samples on methyl orange solution. The results of X-ray diffraction showed that the hexagonal wurtzite structure of ZnO changed little by Cu2+ doping. With the increase in doping concentration, the CuO and Cu2O diffraction peaks were detected successively in the crystal. The results of the electron paramagnetic resonance test for all samples indicated three kinds of unpaired electrons with g factors of 2.07, 1.997, and 1.954. Further analysis confirmed them to be Cu2+, V+O, and Zn–H complexes. Photocatalytic degradation results of methyl orange showed that proper doping (c(Cu2+) = 2%) could improve the photocatalytic activity of ZnO. The main reason for the increase was that the substitution of Cu2+ for Zn2+ in the crystal lattice produced Zni, and the Zn atom could act as the donor to release electrons, so that the number of electrons in the material increased, which indirectly increased the superoxide radical content in the solution and improves the photocatalytic activity of ZnO.

Enhanced piezo-photocatalysis in Bi0.5Na0.5TiO3@Ag composite to efficiently degrade multiple organic pollutants

The synergistic piezo-photocatalysis with enhanced efficiency for degrading obstinate pollutants in wastewater is considered as an advanced way to ameliorate the global water contamination. In this work, we report a facile route to construct the Bi0.5Na0.5TiO3@Ag composite by photoreduction of AgNO3 to obtain Ag on Bi0.5Na0.5TiO3 nanoparticles. And the composite was used to degrade three representative pollutants, i.e. ciprofloxacin, methyl orange and mitoxantrone hydrochloride. Remarkably, for methyl orange solution with the initial concentration of 10 mg/L, the degradation rate constant of the composite reached 0.051 min−1. H+ and •O2− play a major role in this degradation process, verified by the radical quenching experiments. The absorption platform of Bi0.5Na0.5TiO3 was located in the UV region, after introducing Ag in the composite, the absorption region broadened to both UV and visible light, greatly promoting the response to light. Simultaneously, the induced piezo-potential by mechanical energy in Bi0.5Na0.5TiO3 hindered the carrier recombination, resulting in high-efficiency synergistic piezo-photocatalytic process. This work provides a paradigm to innovate both material and catalytic way for degrading multiple organic pollutants.

Investigation on the Adsorption Properties of an Engineered Biochar (Fe2o3-Bc) Nano-Composite in Binary and Ternary Aqueous Solutions

The binary and ternary adsorptions of Pb (II), methyl orange (MO) and brilliant blue (BB) on engineered biochar (Fe2O3-BC) nano-composite using pyrolysis and microwave activation were investigated in this work. Batch experiments were conducted to investigate the capacity of Fe2O3BC to remove MO, Pb and BB in binary and ternary aqueous solutions. MO removal was higher in MO-Pb binary solution than in ternary MO solution. A large amount of adsorbent dosage, high concentration and longer time were witnessed to achieve maximum removals in ternary solutions as compared to binary solutions. The Langmuir plots indicated that the isotherm can be used to describe sorption studies of both MO dye and Pb2+, while Temkin isotherm was not in agreement with the results. The closeness of R2 value to 1 indicated that the data obtained fits Langmuir Isotherm model of monolayer adsorption kinetics. It was concluded that the Fe2O3-BC nano-composite has a series of distinct homogeneous sites available for binding the MO anions in solution. Therefore, the use of Fe2O3-BC nano-composite for small scale community water purification is a novel cause.

Preparation of a novel modified nanoscale zero valent iron particles and its decolorization of methyl orange solution

Preparation of a novel modified nanoscale zero valent iron particles and its decolorization of methyl orange solution

Novel alginate immobilized TiO2 reusable functional hydrogel beads with high photocatalytic removal of dye pollutions

Abstract TiO2 semiconductor photocatalysis is an effective technology for the treatment of wastewater containing organic dye pollutants, which has been received extensive focus. However, the problems in the recovery and reutilization process impede the large-scale applications of particulate photocatalytic materials. Herein, a macro sized hydrogel bead loaded with nano TiO2 powder was successfully prepared by taking advantage of the cross-linking and gel property of alginate salt, which could form egg-box structure naturally when Na+ ions in sodium alginate (SA) were replaced by divalent ions such as Cu2+, Co2+, and Sr2+ ions. The photocatalytic degradation rate of methyl orange (MO) solution in the presence of the hydrogel beads reaches 99% within 60 min under the ultraviolet light irradiation, which is competitive with that of TiO2 nano powder. Furthermore, the hydrogel beads prepared by this strategy maintain over 95% photocatalytic degradation rate after 10 cycles of degradation process. The results indicate that the network structure of alginate could immobilize and disperse TiO2 particle effectively, and it is readily for the spherical beads to contact and harvest the light, making the alginate beads have excellent photocatalytic functions. Also, the alginate based beads integrate good performance with high stability and excellent recyclability perfectly.

An Ultrasound Application for TiO2 Photocatalytic Degradation of Methyl Orange

Nanometer TiO2 photocatalysts were prepared by the sol–gel method. The catalysts were characterized by X-ray diffraction, Fourier-transform infrared spectroscopy, ultraviolet-visible spectroscopy, and other techniques. Methyl orange solution was used for the degradation of the organic material and ultrasonic technology was used to determine the photocatalytic performance of the catalysts. The results show that the photocatalytic performance of the Ni-N-TiO2 is clearly improved under ultrasonic conditions. The TiO2 photocatalytic degradation effect is optimal at a catalyst concentration of 0.3 g/L, an initial concentration of the organic matter of 0.03 mmol/L, a nickel-doping amount of 2 mol %, and a nitrogen-doping amount of 15 mol %. The use of ultrasound technology in combination with photocatalysis has a positive effect and results in a TiO2 degradation rate of methyl orange of 95 % after 3 h.

A Facile One-Pot Approach to the Fabrication of Nanocellulose-Titanium Dioxide Nanocomposites with Promising Photocatalytic and Antimicrobial Activity.

The combination of cellulosic materials and metal oxide semiconductors can provide composites with superior functional properties compared to cellulose. By using nanocellulose derived from agricultural waste, we propose a one-pot and environmentally friendly approach to the synthesis of nanocellulose–TiO2 (NC–TiO2) nanocomposites with peculiar photocatalytic activity and antibacterial effects. The as-prepared NC–TiO2 composites were fully characterized by different techniques, such as X-ray diffraction (XRD), μ-Raman, Fourier transform infrared spectroscopy (FTIR), thermogravimetry analysis (TGA), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and diffuse reflectance spectroscopy (DRS). The results showed that well crystalline anatase TiO2 nanoparticles of about 5–6 nm were obtained. The photocatalytic activity in particular was evaluated by using methyl orange (MO) solution as a target pollutant at different pH values. It was found that all the tested NC–TiO2 nanocomposites showed stable photocatalytic activity, even after consecutive photocatalytic runs. In addition, NCT nanocomposites with higher TiO2 content showed degradation efficiency of almost 99% towards MO after 180 min of UV illumination. Finally, NC–TiO2 nanocomposites also showed intriguing antimicrobial properties, demonstrating to be effective against Gram-positive (Staphylococcus aureus, Bacillus subtilis) with 20–25 mm of inhibition zone and Gram-negative bacteria (Escherichia coli, Pseudomonas aeuroginosa) with 21–24 mm of inhibition zone, and fungi (Candida albicans) with 9–10 mm of inhibition zone.

Preparation and photocatalytic properties of DyCoO3 by sol-gel method

Using Dy2O3, C4H6CoO4·4H2O, C6H8O7·H2O and HNO3 as the main raw materials, DyCoO3 was successfully prepared by sol-gel method. The DyCoO3 were characterized by TG-DSC, XRD, SEM and FT-IR. Using azo dye methyl orange solution as simulated wastewater, the degradation activity of DyCoO3 under UV irradiation was studied by changing the synthesis temperature and illumination time. The results show that the pure DyCoO3 can be prepared from 750 °C to 1000 °C, DyCoO3 particles were relatively uniform with average grain size of 2–3 μm. The photocatalytic activity of DyCoO3 sample calcined at 800 °C was the best. When DyCoO3 photocatalytic degradation of 10 mg/L methyl orange for 60 min, the degradation rate was close to 100%. This shows that DyCoO3 is a new type of photocatalyst with high efficiency, which lays a foundation for the application of wastewater treatment.

Ag sputtering–assisted phase formation of Ag2S‐decorated ZnS composite sheets and their photoactive performances

AbstractThe Ag2S crystallites–decorated ZnS composite sheets were synthesized by combinational methodology. Two types of ZnS sheet templates were obtained through the vulcanization of ZnO sheets with sulfur precursors of thiourea and Na2S, and then ZnS–Ag2S heterogeneous sheets were obtained with sputtering Ag crystallites and post‐annealing procedures. The ZnS sheets have rugged and smooth surfaces formed with sulfur precursors of thiourea and Na2S, respectively. Both the initial microstructures of ZnS sheet templates and Ag2S decoration content affect the photoactivity of the ZnS–Ag2S composite sheets. Compared with the pristine ZnS, the ZnS–Ag2S composite sheets with a suitable Ag2S loading content (Ag at% = 3.6–3.8) are beneficial to improve the photoactivity, which could be explained by the combination of narrow bandgap; Ag2S crystallites would enhance photon absorption and separation efficiency of photoinduced charge carriers. The scavenger tests and photodegradation mechanism show that hydroxyl radicals and holes were the main active species for the ZnS–Ag2S composite sheets to photodegrade methyl orange solution. The experimental results herein provide a novel synthesis approach to decorate Ag2S crystallites onto ZnS with tunable contents and present important design guidelines for the resultant ZnS–Ag2S composite sheets to demonstrate marked improvement in photoactivity.

Isotherm and Adsorption Thermodynamics Cross-Linked Chitosan Microcapsules of Kalium Pershulphate to Methyl Orange Dye

Modeling of isotherm and adsorption thermodynamics in this study, leads to the determination of the classification of adsorption isotherms and the determination of the amount of energy and entropy to determine the impeccability of the process. As an adsorbent, a potassium persulfate crosslinked chitosan microcapsule was synthesized through a microencaptulation process using a solvent evaporation method with a carboxy methyl cellulose CMC coating. The characteristics of the chitosan microcapsules that were formed had a degree of deacetylation of 53,92 %, and a bn mutant diameter around 1-100 µm. Test materials used azo methyl orange dyes, which are often found in industrial waste and laboratory waste. Observations were made with variations in the concentration of methyl orange solution 5, 7,5, 10, 12,5, 15, 17,5 and 20 ppm at temperatures of 30, 40 and 50 ° C. The calculation results show that the adsorption isotherm model obtained approaches the Langmuir isotherm model. The results of the analysis of temperature effects obtained positive Gibbs energy change values (ΔG) so that the adsorption process takes place non-spontaneously. The values of enthalpy change (ΔH) and entropy change (ΔS) of 33,86 kJ / mol and 0,0899 kJ / mol.K. This indicates that adsorption occurs chemically adsorption, is endothermic and adsorbat is not completely adsorbed.

Photocatalytic Degradation Performance of Fluorine and Nitrogen Co‐doped TiO2/AC Composites over Printing and Dyeing Wastewater under Visible‐Light Irradiation

AbstractPrinting and dyeing wastewater is one of the difficult wastewater to treat because of its complex composition, difficult degradation, high color and high concentration of organic matter. At present, photocatalysis, a chemical treatment method, is playing an increasingly important role in the field of printing and dyeing wastewater treatment. To improve the photocatalytic degradation efficiency of TiO2 on printing and dyeing wastewater, F−N‐TiO2/AC composite photocatalysts were prepared by loading titanium dioxide (TiO2) particles onto activated carbon (AC) using an impregnation‐hydrothermal method and co‐doping with fluorine and nitrogen. The characterization results showed that the TiO2 particles were loaded onto the surface and pores of AC, which increased the specific surface area of the composite and the average particle size of the TiO2 particles was reduced by the co‐doping of fluorine and nitrogen. Using methyl orange solution to simulate dye wastewater, the highest degradation efficiency (100 %) of methyl orange was achieved via F−N‐TiO2/AC composite photocatalysts when the F/TiO2 molar ratio was 0.3 and N/TiO2 molar ratio was 0.5. The rate of adsorption reaction for methyl orange by F−N‐TiO2/AC followed the pseudo second‐order kinetic. The effects of the catalyst dosage, environmental pH and interferences in water on the degradation efficiency of the F−N‐TiO2/AC composite photocatalyst were then investigated. The photocatalytic degradation of methyl orange is well fitted by a first‐order kinetic model and the degradation rate is 0.09616 min−1, which is about 6 times higher than that of TiO2/AC composites. Meanwhile, the F−N‐TiO2/AC composite photocatalyst had good recycling performance and the degradation efficiency toward methyl orange was still >80 % after five times of repeated use.