Photocatalytic Degradation Of Acid Orange Research Articles

Nitrogen‐Rich Carbon Nanodot‐Sensitized TiO2 with MWCNT Composites for Efficient Visible Light Photocatalysis

AbstractTiO2‐based composite photocatalysts are currently being explored to address concerns intrinsic to TiO2, specifically high charge carrier recombination and UV light activation. Among various materials utilized for composite formation, carbon nanomaterials stand out due to their high electron conductivity, charge storage, photosensitization, and surface properties. However, high carbon content in composites has been shown to reduce performance with potential toxicity concerns. To harness the diverse properties of carbon nanomaterials in a single composite while optimizing the carbon content below 1% by weight, multi‐walled carbon nanotubes (MWCNT)/TiO2 sensitized by carbon nanodots (CND) are synthesized. The heterojunction formed between MWCNTs and TiO2 in the binary composite reduced the charge carrier recombination rate compared to TiO2. The addition of CNDs to MWCNT/TiO2 induced visible light absorbance of the resulting ternary composite, due to the forbidden electron transitions undergone in CND aggregates. CND/MWCNT/TiO2 exhibited a fivefold and 1.6‐fold increase in photocatalytic degradation of acid orange 7 and tetracycline under visible light compared to TiO2. This enhancement is attributed to the photosensitizing property of CNDs working in synergy with the charge storage ability of MWCNTs. A plausible charge transfer pathway for the activity of CND/MWCNT/TiO2 is proposed.

Postindustrial Jute Waste as a Support for Nano-Carbon Nitride Photocatalyst: Influence of Chemical Pretreatment.

Non-woven jute (NWJ) produced from carpet industry waste was oxidized by H2O2 or alkali-treated by NaOH and compared with water-washed samples. Changes in the structure of the NWJ, tracked by X-ray diffraction (XRD), showed that both chemical treatments disrupt hydrogen bond networks between cellulose Iβ chains of the NWJ fibers. Thereafter, nano-carbon nitride (nCN) was impregnated, using a layer-by-layer technique, onto water-washed jute samples (nCN-Jw), NaOH-treated samples (nCN-Ja) and-H2O2 treated samples (nCN-Jo). Analysis of the Fourier transform infrared spectroscopy (FTIR) spectra of the impregnated samples revealed that nCN anchors to the water-washed NWJ surface through hemicellulose and secondary hydroxyl groups of the cellulose. In the case of chemically treated samples, nCN is preferentially bonded to the hydroxymethyl groups of cellulose. The stability and reusability of prepared nCN-jute (nCN-J) samples were assessed by tracking the photocatalytic degradation of Acid Orange 7 (AO7) dye under simulated solar light irradiation. Results from up to ten consecutive photocatalytic cycles demonstrated varying degrees of effectiveness across different samples. nCN-Jo and nCN-Ja samples exhibited declining effectiveness over cycles, attributed to bond instability between nCN and jute. In contrast, the nCN-Jw sample consistently maintained high degradation rates over ten cycles, with a dye removal percentage constantly above 90%.

Automated Monitoring System for Suspended Photocatalytic Batch Reactions Based on Online Circulatory Spectrophotometry.

Employing an automated monitoring system (AMS) for data acquisition offers benefits, such as reducing the workload, in the kinetic study of suspended photocatalytic batch reactions. However, the current methods in this field tend to narrowly focus on the substrate and often overlook the optical characteristics of both the mixture and solid particles. To address this limitation, in this study, we propose a novel AMS based on online circulatory spectrophotometry (OCS) and incorporate debubbling, aeration, and segmented flow (DAS), named DAS-OCS-AMS. Initially, a debubbler is introduced to mitigate the issue of signal noise caused by bubbles (SNB). Subsequently, an aerated and segmented device is developed to address the issue of particle deposition on the inner wall of the pipeline (PDP) and on the windows of the flow cell (PDW). The proposed DAS-OCS-AMS is applied to monitor the kinetics of the photocatalytic degradation of Acid Orange Ⅱ by TiO2 (P25), and its results are compared with those obtained using the traditional OCS-AMS. The comparative analysis indicates that the proposed DAS-OCS-AMS effectively mitigates the influence of SNB, PDP, and PDW, yielding precise results both for the mixture and solid particles. The DAS-OCS-AMS provides a highly flexible universal framework for online circulatory automated monitoring and a robust hardware foundation for subsequent data processing research.

Using a promising biomass-based biochar in photocatalytic degradation: highly impressive performance of RHB/SnO2/Fe3O4 for elimination of AO7.

The release of industrial dyes into the environment has recently increased, resulting in harmful effects on people and ecosystems. In recent years, the use of adsorbents in photocatalytic nanocomposites has attracted significant interest due to their low cost, efficiency, and eco-friendly physical and chemical characteristics. Herein, Acid Orange 7 (AO7) removal was investigated by photocatalytic degradation using Rice Rusk Biochar (RHB), Tin (IV) Oxide (SnO2), and Iron Oxide (Fe3O4) as heterogeneous nanocomposite. After the preparation of RHB, the nanocomposite was synthesized and characterized using Field Emission Scanning Electron Microscope (FESEM), X-ray Powder Diffraction (XRD), Brunauer-Emmett-Teller (BET), and Fourier-Transform Infrared Spectroscopy (FT-IR). To optimize the elimination of AO7 by the One-Factor-At-a-Time (OFAT) method, effective parameters including mixing ratio (RHB:SnO2:Fe3O4), dye concentration, solution pH, and nanocomposite dose were studied. The results showed that the removal efficiency of AO7 after 120min under the optimal mixing ratio of 1:1.5:0.6, dye concentration of 75mg/l, solution pH of 4, and nanocomposite dose of 0.7g/l was 92.37%. Moreover, Chemical Oxygen Demand (COD) and Total Organic Carbon (TOC) removal rates were obtained at 82.22 and 72.22%, respectively. The Average Oxidation State (AOS) and Carbon Oxidation State (COS) of the AO7 solution were increased after the process, indicating biodegradability improvement. Various scavenger effects were studied under optimal conditions, and the results revealed that O2- and H+ reactive species play a crucial role in the photocatalytic degradation of AO7. The reusability and stability of nanocomposite were tested in several consecutive experiments, and the degradation efficiency was reduced from 92 to 79% after five consecutive cycles. It is expected that this research contributes significantly to the utilization of agricultural waste in photocatalytic nanocomposites for the degradation of environmental pollutants.

Photocatalytic Degradation of Acid Orange 7 by NiO-TiO2/TiO2 Bilayer Film Photo-Chargeable Catalysts

Photocatalysis as an eco-friendly technology has the potential to achieve the Sustainable Development Goals (SDGs). However, an improvement of conventional photocatalysts is necessary to overcome their limitations such as slow kinetics, wavelength for excitation, and environmental restrictions. In particular, the development of a photocatalyst that can operate even in the absence of light is constantly conducted, and a photo-chargeable photocatalyst could be one of the answers. In this paper, a heterojunction composed of TiO2 and NiO-TiO2 bilayer film photocatalyst (BLF) was prepared. The effect of the synthesis conditions of the NiO-TiO2 layer on the photocatalytic properties was investigated. Photocatalytic degradation measurements were conducted with an acid orange 7 (AO7) solution under light and dark conditions. The highest degradation BLF was synthesized at a NiO loading of 52% and calcination temperature of 300 °C. The prepared sample showed about five-fold greater photocatalytic activity of 48% in AO7 degradation after 8 h compared to an ordinary TiO2 film (9%) under light conditions. Moreover, under dark conditions it exhibited 13.6% degradation, while the naked layers of TiO2 and NiO-TiO2 showed no degradation. The proposed mechanism suggested that photocatalysis in the dark was possible due to the stabilization of photogenerated holes by anionic intercalation during illumination.

Efficiency of TiO2/Fe2NiO4 Nanocomposite in Photocatalytic Degradation of Acid Orange 7 (AO7) Under UV Irradiation

Efficiency of TiO2/Fe2NiO4 Nanocomposite in Photocatalytic Degradation of Acid Orange 7 (AO7) Under UV Irradiation

Probing the Photocatalytic Degradation of Acid Orange 7 Dye with Chitosan Impregnated Hydroxyapatite/Manganese Dioxide Composite

Probing the Photocatalytic Degradation of Acid Orange 7 Dye with Chitosan Impregnated Hydroxyapatite/Manganese Dioxide Composite

Aloe barbadensis Mill leaf gel assisted combustion synthesized ZnO:Ni3+: Electrochemical sensor for ascorbic acid detection and photocatalysis

• Nickel (Ni 3+ ) doped ZnO were prepared by aloe vera gel assisted solution combustion technique. • Enhancement of Electrochemical properties in Ni 3+ doped ZnO have been investigated. • The photocatalytic degradation of Acid Orange (AO) and Direct Green (DG) dyes were analysed. A promising nanostructure of pure and Nickel (Ni 3+ ) doped ZnO was prepared by aloe vera gel-assisted solution combustion technique. Electrochemical and photocatalytic investigations of the resulting nanostructures were achieved using cyclic voltammetry and UV–Vis spectrophotometry respectively. Enhancement of electrochemical properties in Ni 3+ doped ZnO nanostructures was studied. The results suggest that the doped ZnO exhibits a dramatic electrocatalytic effect on the oxidation of ascorbic acid (AA). It was observed that 1 mol% Ni 3+ doped ZnO electrode can show a redox peak for 1 millimolar (mM) level AA. It has been shown that these modified electrodes can be used as a sensor for different concentrations of AA. The photocatalytic analysis was performed for the degradation of Acid Orange (AO) and Direct Green (DG) dyes. It shows that the AO and DG dyes are potential dyes for the degradation of textile dye pollutants and the elimination of secondary pollutants.

Rate of Photocatalytic Degradation of Acid Orange 7 Azo Dye on TiO2 Coated Layers: Role of pH and Initial Dye Concentration

This paper examined the role of pH and initial dye concentration on the rate of Acid Orange 7 photocatalytic degradation. A batch mode plate photocatalytic reactor fitted with a TiO2 coated layer of dimensions (10cm×15cm) immobilized on microscopic glass was used. The coated layer was prepared by sedimentation from an aqueous suspension of 5 g.L-1 phase and annealed at 300°C. Polychromatic sun beds lamps were used as a source of Ultra Violet (UV) light with maximum intensity at wavelength λ= 365 nm. An appropriate dye solution flow rate of 50 lit/hr was used. A UV-Vis spectrophotometer monitored changes in dye concentrations at λ_max= 485 nm. From changes in dye concentration during irradiation the rate of photocatalytic degradation was determined. The findings reveal that pH range 5 to 9 the degradation rate is almost constant, for pH values lower than 5 it marginally increases while for pH values above 9 it significantly decreases. Additionally the degradation rate increased significantly with increasing initial dye concentration in the range from (1×10-5 mol.L-1 to 8×10-5 mol. L-1). The amount of adsorbed Acid Orange 7 increases with increased dye concentration, however for concentrations greater than 1×10-4 mol. L-1 it was observed that the increase was marginal. The findings confirm a direct correlation between the amount of dye adsorbed and resultant degradation rate. The optimum pH and initial dye concentration were determined ;[( pH= 3, r=1.6×10-7 mol.m-2.s-1); (initial concentration = 8×10-5 mol.L-1 to 1×10-4 mol.L-1, r= 3×10-7 mol.m-2.s-1)]. A shift in dye solution pH from acidic to basic in the range 3 to 11.5 reduced photocatalytic degradation rates by 56.3%.

Synthesis and Oxygen Storage Capability of CeO2 Powders for Enhanced Photocatalytic Degradation of Acid Orange 7

Acid Orange 7 (AO7) is one of the most common azo dyes; however, its strong azo bond makes them difficult to biologically degrade. We sought to degrade AO7 dye using CeO2 as a promising alternative photocatalyst. CeO2 powders were synthesized with alternative monoethanolamine (MEA), diethanolamine (DEA), and triethanolamine (TEA) as a precipitant by solvothermal process combined calcination in air. Compared to the oxygen storage capability of Blank-CeO2 (0.186 mmol O2/g), that of MEA-CeO2 synthesized in the presence of MEA as a precipitant increased by 21.0%, while that of DEA-CeO2 and TEA-CeO2 synthesized in the presence of DEA and TEA as precipitants were decreased. Importantly, such MEA-CeO2 exhibited the highest photocatalytic activity than Blank-, DEA-, and TEA-CeO2 in degradation of AO7 under simulated sunlight illumination, and the removal rate of AO7 by MEA-CeO2 could reach 98.3% within 100 min.

Photocatalytic Degradation of AO7 Aqueous Solution Using Ag/CeO2 Catalyst: Modeling of Process Parameters Using Response Surface Methodology

In the present study, photocatalytic degradation of Acid Orange 7 (AO7) aqueous solution using Ag/CeO2 catalyst with the presence of UV light was evaluated. The effect of process parameters such as pH, initial dye concentration and Ag/CeO2 dosage were investigated using response surface methodology (RSM) based on three levels of Box-Behnken Design. The effect of process parameters and their binary interactions were analyzed using the polynomial regression model. The experimental data and ANOVA analysis showed that the determination coefficient (R2) and adjusted determination coefficient (R2 adj) were 0.9580 and 0.9161, respectively, demonstrated that the model was significant. The response surface plot was successfully established the interaction effect of process parameters on the photocatalytic degradation of AO7 aqueous solution.

Facile Hydrothermal Synthesis of Copper Chromite Nanoparticles for Efficient Photocatalytic Degradation of Acid Orange 7 Dye

Facile Hydrothermal Synthesis of Copper Chromite Nanoparticles for Efficient Photocatalytic Degradation of Acid Orange 7 Dye

Enhanced synergistic photocatalytic activity of TiO2/oxidant for azo dye degradation under simulated solar irradiation: A determination of product formation regularity by quantifying hydroxyl radical-reacted efficiency

Synergizing heterogeneous photocatalysis with strong oxidants is a simple and useful way towards the improvement of organic wastewater treatment. This study verified that the synergies of TiO2 and two oxidants, K2Cr2O7 (Cr(VI)) and KMnO4 (Mn(VII)), can effectively improve the degradation of an azo dye acid orange 7 (AO7) under simulated solar irradiation, which is based on a combination of the oxidizing ability of oxidants and the enhanced synergistic photocatalytic activity. Meanwhile, nearly 60 % of toxic Cr(VI) could be photocatalytically reduced into innocuous Cr(III) species, being free from secondary contamination. The measurements of hydroxyl radicals (OH) and superoxide radicals (O2−) by using electron spin resonance (ESR) and fluorescence probe techniques, indicated that the enhanced synergistic photocatalytic activity of TiO2/oxidant can be attributed to the facilitated separation of electron–hole pairs and the increased utilization of electrons, thus promoting overall OH formation. Analyzed by liquid chromatography–mass spectrometry (LC/MS), the intermediate product distributions of AO7 degradation were determined to further propose the possible degradation pathways. Through applying the quantification of OH-reacted efficiency, it was found that the OH-reacted concentration shows a satisfactory linear correlation (r = 0.924) with AO7 degradation. The OH-reacted concentration was thereby adopted as an indicator parameter to further establish a stoichiometry of OH which can be used to quantitatively describe the occurring mechanisms and product formation characteristics during the photocatalytic degradation of AO7. This study provides an experimental approach for revealing the regularity of product formation in the wastewater treatment by various OH-based advanced oxidation processes.

Response surface methodology and artificial neural network for remediation of acid orange 7 using TiO2-P25: optimization and modeling approach.

The primary responsibility for continuously discharging toxic organic pollutants into water bodies and open environments is the increase in industrial and agricultural activities. Developing economical and suitable methods to continuously remove organic pollutants from wastewater is highly essential. The aim of the present research was to apply response surface methodology (RSM) and artificial neural networks (ANNs) for optimization and modeling of photocatalytic degradation of acid orange 7 (AO7) by commercial TiO2-P25 nanoparticles (TNPs). Dose of TNPs, pH, and AO7 concentration were selected as investigated parameters. RSM results reveal the reflective rate of AO7 removal of ~ 94.974% was obtained at pH7.599, TNP dose of 0.748g/L, and AO7 concentration of 28.483mg/L. The resulting quadratic model is satisfactory with the highest coefficient of determination (R2) between the predicted and experimental data (R2 = 0.98 and adjusted R2 = 0.954). On the other hand, ANNs were successfully employed for modeling of AO7 degradation process. The proposed ANN model was absolutely fitted with experimental results producing the highest R2. Furthermore, root mean square error (RMSE), mean average deviation (MAD), absolute average relative error (AARE), and mean square error (MSE) were examined more to compare the predictive capabilities of ANN and RSM models. The experimental data was well fitted into pseudo-first-order and pseudo-second-order kinetics with more accuracy. Thermodynamic parameters, namely enthalpy, entropy, Gibbs' free energy, and activation energy, were also evaluated to suggest the nature of the degradation process. The increase of temperature was analyzed to be more suitable for the fast removal of AO7 over TNPs. Graphical abstract.

A Z-scheme mechanism of the novel ZnO/CuO n-n heterojunction for photocatalytic degradation of Acid Orange 7

A series of novel ZnO/CuO n-n heterojunction photocatalysts were synthesized with a microwave assisted method. The structures, morphologies, optical properties, and chemical states of these prepared photocatalysts were systematically characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, UV–vis diffuse reflectance spectroscopy, and X-ray photoelectron spectroscopy. The results indicated that the crystalline structures and morphologies of ZnO and ZnO/CuO are both quasi-sphere shape wurtzite structures. The photocatalytic activities of ZnO/CuO heterojunction were evaluated by the degradation of Acid Orange 7 under simulated solar light irradiation. The results indicated that the ZnO/CuO n-n heterojunctions all have higher photocatalytic activities than the pure ZnO and the ZnO/CuO(2) sample with 2% of CuO exhibits the highest performance for degradation of Acid Orange 7. These could be due to the effective enhancement of electron-hole separation and weaken charge transfer resistance in ZnO/CuO n-n heterojunction, as indicated by their photoluminescences, the electrochemical impedance spectra, and photocurrent responses. Finally, Z-scheme electron transfer mechanism was proposed as the major photocatalytic mechanism of ZnO/CuO materials.

TiO2 supported on Salvinia molesta biochar for heterogeneous photocatalytic degradation of Acid Orange 7 dye

Composites were prepared using Salvinia molesta biochar as a carbonaceous anchor for TiO2, employing two synthesis routes: sol-gel and mechanical mixing. TTiP and TiOSO4 were tested as TiO2 precursors. The composites were characterized using IR spectra, X-ray diffractograms, band gap energies, g Factor of EPR, surface areas, pore sizes and volumes, and scanning electron micrographs of the surfaces. For both synthesis routes, the composites prepared from TTiP showed higher crystallinity, lower band gap, and larger pore size. Due to these characteristics, the samples produced using this precursor presented the best performance in terms of both adsorption (46.5% at 60 min) and photocatalytic efficiency (57.6% at 180 min) under UV irradiation (F15 bulb, GE, 15 W, wavelength range ˜380 – 480 nm). The results showed that the impregnation method had a smaller influence on the photocatalytic efficiency of the composites, compared to the effect of the type of TiO2 precursor. However, impregnation by mechanical mixing produced composites that presented higher performance, compared to use of the sol-gel method. This sample presented similar ability to degrade the AO7 in up to six recycles. The OH and O2− radicals generated by composite were the main responsible for photodegradation of AO7 and quinone-like structures present in salvinia’s biochar, being the major electron acceptors responsible for decreasing the electron/hole recombination.

Kinetic study on photocatalytic degradation of Acid Orange 52 in a baffled reactor using TiO2 nanoparticles

In this study, a baffled photocatalytic reactor was used for the treatment of colored wastewater containing the azo dye of Acid Orange 52 (AO52). A study on the active species of the photocatalytic process using TiO2 nanoparticles indicated that hydroxyl radical and superoxide have the greatest contribution to the dye degradation process respectively. Given that a level of biological oxygen demand/chemical oxygen demand (BOD5/COD) equal to 0.4 was achieved after about 5 hr from the beginning of the experiment, the reactor seems to be capable of purifying the wastewater containing AO52 dye after this time in order to discharge into a biological treatment system to continue the treatment process. The results of the liquid chromatography-mass spectrometry (LC-MS) test showed that during the first 4 hr of the experiment, with the breakdown of the azo bond, the contaminant was decomposed into the benzene annular compounds with less toxicity indicating a reduction in the toxicity of wastewater after removing the dye agent. The study on the kinetics of these reactions followed the pseudo-first-order kinetic model in all conditions and corresponded well to Langmuir–Hinshelwood model. According to the kinetic model for the simultaneous occurrence of possible pathways, the kinetic constant of production and degradation of intermediate products in optimal conditions was estimated to be between 0.0029 and 0.0391 min−1.

Enhanced Photocatalytic Degradation of Acid Orange 7 by AgBr/BiVO4 under Visible Light

Enhanced Photocatalytic Degradation of Acid Orange 7 by AgBr/BiVO4 under Visible Light

Efficient surface design of reduced graphene oxide, carbon nanotube and carbon active with cupper nanocrystals for enhanced simulated-solar-light photocatalytic degradation of acid orange in water

A series of cupper/carbon based hybrid nanostructured composites is fabricated. Their photocatalytic performance has been investigated for photocatalytic degradation of acid orange 7. Physicochemical properties of the samples were characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), Transition electron microscopy (TEM), Energy dispersive X-ray analysis (EDX), Fourier Transform Infrared Spectroscopy (FTIR), the Brunauer–Emmett–Teller (BET) surface area analyzer and UV–vis diffuse reflectance spectroscopy (DRS) techniques. Reactor tests indicate that Cu/RGO nanocomposite possess much higher photoactivity than Cu/MWCNT and Cu/AC. The pHpzc of Cu/RGO nanocomposite was further determined to be 6 by drift method. The superior photoactivity of Cu/RGO among Cu/MWCNT and Cu/AC is mainly because of a synergistic effect between RGO and Cu nanoparticles. In fact, excellent charge carrier mobility on the surface of RGO prolongs recombination of excited electrons; which results in improved photocatalytic performance of Cu/RGO. Furthermore, superconductivity of RGO due to its particular lattice, superior electron mobility and their electron acceptor behavior is regarded as an effective component in photocatalysis heterojunction systems. The effect of dye concentration, catalyst dosage and pH on degradation performance investigated.

Sol-Gel Hydrothermal Synthesis and Visible Light Photocatalytic Degradation Performance of Fe/N Codoped TiO₂ Catalysts.

Using Ti(OC4H9)4 as a precursor, Fe(NO3)3⋅9H2O as the source of iron, and NH4NO3 as the source of nitrogen, an Fe/N codoped TiO2 catalyst was prepared using a sol-gel hydrothermal method. The as-prepared powders were characterized using X-ray powder diffraction, electron spectroscopy for chemical analysis, Fourier-transform infrared spectroscopy, and ultraviolet-visible spectrophotometry. Fe and N codoping resulted in decreased crystallite size and increased specific surface area. Results of the photocatalytic degradation of acid orange 7 (AO7) in a continuous-flow fluidized-bed reactor indicated that the maximum decolorization (more than 90%) of AO7 occurred with the Fe/N-TiO2 catalyst (dosage of 20 g/L) when a combination of visible light irradiation for 10 h HRT (hydraulic retention time), and a heterogeneous system was used. The AO7 degradation efficiency was considerably improved by increasing the hydraulic retention time from 2.5 to 10 h or by reducing the initial AO7 concentration from 300 to 100 mg/L. The reaction rate increased with the light intensity and the maximum value occurred at 35 mW/cm2; moreover, the efficiency of the AO7 degradation increased when the pH decreased with maximum efficiency at pH 3.