Photodegradation Of 4-nitrophenol Research Articles

Green synthesis of novel Zn0.5Ni0.5FeCrO4 spinel magnetic nanoparticles: Photodegradation of 4-nitrophenol and aniline under visible light irradiation

This study explores novel nanoparticles used in environmental remediation of 4-nitrophenol and aniline from wastewater bodies. The Zn0.5Ni0.5FeCrO4 magnetic nanoparticles (MNPs) were synthesized using tragacanth gel as a green, low-cost, and easy sol-gel method. The MNPs were characterized by XRD, XPS, FT-IR, VSM, TEM, EDX, FESEM, BET, DRS, and elemental mapping. The analysis demonstrated that nanoparticles have a spinel cubic structure, spatial distribution of the elements, ferromagnetic activity, narrow bandgap, and uniform morphology. Furthermore, effectiveness of the developed MNPs to degrade recalcitrant organic pollutants such as 4-nitrophenol (4-NP) and aniline under visible light exposure were studied. The results indicated 95% aniline and 80% of 4-NP were successfully degraded in 180 and 150 min, respectively. The total organic carbon (TOC) analysis revealed 65% and 54% removal of aniline and 4-NP. LC-MS was employed to elucidate the photodegradation mechanism and to identify the degradation products, including small fragmented molecules.

Effect of initial solution pH on 4-nitrophenol oxidation through homogeneous/heterogeneous photo-Fenton process using goethite/H2O2 system

The photodegradation of 4-nitrophenol (4-NP) through homogeneous/heterogeneous photo-Fenton process was examined in the presence of goethite (α-FeOOH)/H2O2/UV system in solution at different pH values. The degradation of 4-NP was achieved with excellent performance. Conversion reached 100%, 92% and 83% in the first 120 min of irradiation for acidic, point of zero charge (pzc) and weakly alkaline pH, respectively. Meanwhile, 69% of degradation was reached under strong alkaline pH conditions and this resulted in the weakest removal percentage under comparable experimental conditions. The rate of photocatalytic degradation followed pseudo-first order kinetics with kinetic constants of 6.30 × 10−2 min−1, 2.37 × 10−2 min−1, 1.73 × 10−2 min−1 and 0.70 × 10−2 min−1 at pH = 3.0, 5.5, 9.0 and 11.0, respectively. The iron(II) species dissolved in the solution enhanced the photocatalytic degradation and the hydroxyl radicals (OH) production. The involvement of free radicals was evidenced by using scavengers and the results revealed that OH is the main active species. The stability of goethite to repeated uses was investigated too and, after five runs, the removal efficiency of 4-NP was still complete, with values attaining 100%.

Photodegradation of 4-Nitrophenol by Visible-Light Driven Ternary Nanocomposite of N-TiO2 and Ag3PO4 Co-Grafted on Graphene Oxide: Influence of System Parameters and Kinetic Study

Photodegradation of 4-Nitrophenol by Visible-Light Driven Ternary Nanocomposite of N-TiO2 and Ag3PO4 Co-Grafted on Graphene Oxide: Influence of System Parameters and Kinetic Study

An investigation on photocatalytic and α-amylase inhibitory activities of Co(II) and Zn(II) phthalocyanines

Metallophthalocyanines have broad range of photocatalytic and biological applications, so they have been investigated widely by the scientific community. In this study, P4P-1 and P4P-2 phthalocyanines and their water soluble derivatives (QP4P-1 and QP4P-2) were synthesized and characterized by different spectral data. Photocatalytic performance of QP4P-1 and QP4P-2 were tested on photodegradation of 4-nitrophenol (4-NP). QP4P-1 shows remarkable photocatalytic activity with 90 % product conversion (TON:1500) in aqueous solution of 4-nitrophenol. α-amylase inhibition assay is performed in order to find out the enzyme inhibitory potential of water soluble phthalocyanine QP4P-2. QP4P-2 inhibited α-amylase 64.2 ± 0.8 % at 300 µM concentration and the IC50values ​​of the molecule was calculated as 128.2 ± 1.5 µM. QP4P-2 reflects the potential α-amylase inhibitory activity as compared to others.

Nanosponge-C3N4 composites as photocatalysts for selective partial alcohol oxidation in aqueous suspension.

A set of four composite materials was prepared, consisting of a nanosponge matrix based on β-cyclodextrin in which carbon nitride was dispersed. The materials were characterized by the presence of diverse cross-linker units joining the cyclodextrin moieties, in order to vary the absorption/release abilities of the matrix. The composites were characterized and used as photocatalysts in aqueous medium under UV, visible and natural solar irradiation for the photodegradation of 4-nitrophenol, and for the selective partial oxidation of 5-hydroxymethylfurfural and veratryl alcohol to the corresponding aldehydes. The nanosponge-C3N4 composites showed higher activity than the pristine semiconductor, which can probably be attributed to the synergic effect of the nanosponge, capable of increasing the substrate concentration near the surface of the photocatalyst.

Facile synthesis of NiO-loaded g-C3N4 heterojunction photocatalyst for efficient photocatalytic degradation of 4-nitrophenol under visible light irradiation

Finding acceptable noble-metal-free cocatalyst-modified photocatalysts has gotten a lot of interest in the field of photocatalysis. In this study, an environmentally friendly ultrasonic-assisted approach was used to make NiO-loaded g-C3N4. The crystal, morphological structure, surface analysis, and optical properties of the pure g-C3N4 and NiO-loaded g-C3N4were characterized by PXRD, TEM, BET, XPS, and UV–vis (DRS), respectively. UV–vis (DRS) results investigated that NiO-loaded g-C3N4 photocatalysts exhibit a reduction in the optical band gap energy related to the bare g-C3N4 that is particularly good for visible light absorption. TEM images prove the existence of the NiO in the NiO-loaded g-C3N4 which is very beneficial for the enhancement of the charge separation and transfer that is revealed using the electrochemical methods. Furthermore, Mott-Schottky plots showed that both bare g-C3N4 and NiO-loaded g-C3N4 photocatalysts have negative flat band potential. Importantly, the photocatalytic activity of NiO-loaded g-C3N4 photocatalysts was evaluated for the photodegradation of 4-nitrophenol (4-NP) in an aqueous solution under visible light irradiation. The optimized ratio of NiO-loaded g-C3N4 (11 wt% loaded g-C3N4)displays the highest activity performance and is almost 4 times higher than that of bulk g-C3N4. The remarkable photocatalytic improvement of NiO-loaded g-C3N4 is mainly attributed to the decreased band gap energy and synergistically enhanced charge separation and transfer. Additionally, the proposed photodegradation mechanism of NiO-loaded g-C3N4 was also deliberated in more detail. Hence, the NiO-loaded g-C3N4photocatalyst is an attractive photocatalyst for photocatalytic water treatment.

A spherical fountain prototype photoreactor operated under natural sunlight: Mechanism, toxicology assessment, and economics

Many investigations have reported the study of dispersed nanoparticle photocatalysts on a laboratory scale. Herein, we present a working spherical fountain prototype photoreactor spray-coated with galvanic sludge to prevent agglomeration and increase surface activity. The degradation process was performed under natural sunlight to make the process sustainable. This photocatalytic reactor exhibited an efficiency of 90.4 % during the photodegradation of 4-Nitrophenol at the optimal conditions of a pollutant concentration of 25 ppm with a photocatalyst loading of 5 g at a natural pH for an operating volume of 7 L with an addition of 0.7 mL of H2O2. Detailed specific surface area, pore volume, pore diameter, shape, and agglomeration were studied by BET and HRTEM. There was a significant change observed in the morphology and crystallinity of the recycled photocatalyst, which could be due to photo-corrosion, as shown in the FESEM and XRD analyses. Moreover, a detailed mechanism was elucidated to understand the fate of 4-Nitrophenol during photodegradation. Furthermore, a toxicology assessment was conducted for the pollutant before and after degradation using Escherichia coli, which showed a decrease in the toxicity. Lastly, an economic evaluation was carried out to deduce the cost of treating 1 m3 of wastewater, which was determined to be USD 10.8/m3 for this photoreactor model.

Sol-gel template synthesis of visible photoactive Cu-S co-doped mesoporous TiO2 catalyst

A new visible photoactive catalyst (Cu, S/PEG-PVA/TiO2) was synthesized by the sol-gel method. In addition, Cu, S/TiO2 and Bare TiO2 were synthesized to compare their properties and activities. The synthesized catalysts were characterized using XRD, N2 adsorption–desorption measurements, SEM, TEM, EDX, UV-Vis spectroscopy and TGA. The photocatalytic activities of the synthesized photocatalysts were evaluated by measuring the photocatalytic degradation of 4-nitrophenol under visible light irradiation. Then, the impacts of three parameters, (catalyst loading, pH and H2O2 concentration) for optimization and modelization of the 4-nitrophenol photodegradation were studied using the response surface methodology. Optimal conditions obtained from statistical analysis at a catalyst loading of 1 gL−1, pH of 3.98 and H2O2 concentration of 8 mg/L have shown the highest 4-NP percentage degradation of 70.5% in 1 h. The results predicted by the models were found to be in good agreement with those obtained by performing the experiment (R 2 = 0.9443 and Adj-R 2 = 0.9038).

Process optimization, characterization and economic evaluation of nanoparticles derived from galvanic sludge for photodegradation of 4-nitrophenol under natural sunlight

The United Arab Emirates has an average of 10 h of sunlight and is available almost throughout the year. This energy has a huge potential to be utilized in photodegrading wastewater. To engineer a sustainable photocatalyst, the waste (galvanic sludge) obtained from the galvanization industry was utilized to degrade 4-nitrophenol under natural sunlight. Detailed morphological, chemical, and optical characterization of galvanic sludge (GS) was performed by UV-DRS, FESEM-EDX, XRD, XPS, PL, FTIR, and GC-MS. RSM-CCD was utilized for optimizing the three key parameters, such as pH, photocatalyst loading, and 4-nitrophenol concentration. The highest photodegradation efficiency of about 94.5% was obtained for a 4-nitrophenol concentration of 30 ppm with a photocatalyst loading of 0.02 g at a pH of 6 with 0.01 mL of H2O2. Based on the analysis of variance results, the R2 value of the overall model was 98.1%, which indicated that the obtained model was well suited for degrading 4-nitrophenol. An economic evaluation was performed for applicability in the real world. For this photodegradation model, the cost of treatment was determined to be USD 17.5/m3. To the best of our knowledge, for the first time we have innovatively used GS as an efficient photocatalyst for treating 4-nitrophenol.

Construction Dual Vacancies to Regulate the Energy Band Structure of Znin2s4 for Enhanced Visible Light-Driven Photodegradation of 4-Nitrophenol

Construction Dual Vacancies to Regulate the Energy Band Structure of Znin2s4 for Enhanced Visible Light-Driven Photodegradation of 4-Nitrophenol

Phytogenic Synthesis and Characterization of NiO-ZnO Nanocomposite for the Photodegradation of Brilliant Green and 4-Nitrophenol

The NiO-ZnO nanocomposite (NiO-ZnO NC) was synthesized by ecofriendly process by using Diospyros kaki (D. kaki) extract of leaves as reducing and capping agents. X-ray diffraction (XRD) was used for examined crystallinity, cell dimensions, and crystallite size (7.6 nm). To determine the purity of sample and weight percentage, energy dispersive X-ray (EDX) is used. The surface morphology was determined by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). By using Fourier transform infrared spectroscopy (FTIR), functional groups in samples were determined. By using diffuse reflectance data (DRS), band gap energy calculated via Tauc plot was 3.23 eV. The photocatalytic activity was checked against brilliant green (BG) and 4-nitrophenol (4-NP) and 92.5% and 69.7% of brilliant green (BG) and 4-nitrophenol (4-NP) were degraded with rate of degradation which were 0.0281 and 0.011 min−1.

Facile synthesis of a novel BaSnO3/MXene nanocomposite by electrostatic self-assembly for efficient photodegradation of 4-nitrophenol

Photocatalysis is regarded as one of the most effective strategies for the removal of the toxic organic pollutants from aqueous solutions. However, a lack of the efficient photocatalysts prevents the widespread practical application. Herein, the electrostatic self-assembly method has been designed for facile synthesis of a novel BaSnO3/PDDA/MXene (BSO/P/MX) nanocomposite as high efficient photocatalyst. In this nanocomposite, the BaSnO3 (BSO), poly (dimethyl-diallylammonium chloride) (PDDA) and MXene (Ti3C2Tx) act as the active species, structure stabilizer and efficient electron transfer medium, respectively. Due to the strong synergy of the nanocomposite, the electron-transferring ability as well as the charge separation efficiency is boosted and thus high catalytic activity achieves towards the photodegradation of 4-nitrophenol. The superior degradation rate of 98.8% and a rate constant K of 0.09113 min−1 have been realized within 75 min of ultraviolet (UV) light irradiation over the BSO/P/MX-8% catalyst. This as-prepared nanocomposite with the excellent catalytic activity can be employed as a promising photocatalyst for treating the organic pollutants from aqueous solutions.

Effective photodegradation of 4-nitrophenol with CuO nano particles prepared by ionic liquids/water system

The hydrophobic ionic liquids/water two-phase system was developed to prepare CuO nano particles. The catalytic activity of the synthesized CuO was investigated by photodegradation of 4-nitrophenol (4-NP) in the presence of H2O2 under visible light irradiation. The optical properties of the synthesized CuO were characterized by ultraviolet–visible (UV–Vis) diffuse reflectance spectroscopy (DRS). Experimental results indicated that the band gap energy (Eg), conduction band edge potential (ECB) and valence band edge potential (EVB) of the synthesized CuO were 1.37 eV, 0.625 eV and 1.995 eV, respectively. A degradation efficiency of 4-NP (4.8 mmol L−1) as high as 95.3% could be achieved under the conditions of pH 6.0, 0.48 g L−1 of CuO dosage, 1.4% of H2O2 dosage and 90 min of degradation time. The synthesized CuO exhibited poor catalytic activity under alkaline conditions due to the disassociation of 4-NP, which elevated the repulsion between CuO and the 4-NP anions. The synthesized CuO nano particles exhibited higher catalytic activity compared with the catalysts reported in literature. Furthermore, the synthesized CuO nano particles could be reused at least six times without decreasing their catalytic activity. Compared with the traditional hydrothermal method, mild operating conditions and time saving are the advantages of the developed method for the preparation of CuO.

Boron Doped TiO2 For The Photodegradation of 4-nitrophenol: Optimization of The Doping Parameters

In this work we prepared boron doped TiO2 (B-TiO2) photocatalysts and evaluated their photocatalytic activity for the degradation of our model organic pollutant, 4-nitrophenol (4-NP). The photocatalysts were prepared using wet impregnation method with different calcination times, calcination temperatures and dopant amounts in order to determine the optimum parameters. The degradation of the pollutant was carried out in a specially designed degradation chamber and characterized by UV-Vis spectrophotometry. The degradation kinetics were evaluated with pseudo-first order kinetics by comparing rate constants and half-lives of various photocatalytic reactions. It was found that the highest removal rate was obtained for 0.50 % boron doping with calcination at 450°C for 3 hours. The results showed that TiO2 could be doped with boron, which is in abundance in our country, and used for the photocatalytic degradation of a toxic pollutant in water. The promising results for the organic matter removal could pave the way for further studies of environmental applications.

The Study of Co–Ni-Mn Ferrites for the Catalytic Decomposition of 4-Nitrophenol

In this work, Co–Ni-Mn ferrites were prepared using a modified chemical co-precipitation method with contact nonequilibrium low-temperature plasma treatment. The structural properties of the ferrites samples were systematically studied using XRD, EPR spectroscopy, vibration magnetometry, and UV-VS spectra analysis. The photocatalytic properties of the prepared samples were comparatively studied during the photodegradation of 4-nitrophenol under UV illumination. The photodegradation rate of 4-nitrophenol (4-NP) in the photocatalytic process was 68–92%, depending on the composition of ferrites. The values of the reaction constant of 4-nitrophenol degradation were calculated. The simplex analysis method made it possible to establish the dependence of the photocatalytic properties of ferrites on the type of EPR spectrum and energy band gap. It was found that for the decomposition reaction of 4-NPs, the intensity of the EPR spectrum peak correlates with photocatalytic activity ferrites. It was established that the optimal compositions for the decomposition of 4-nitrophenol correspond to complex ferrites of nickel and cobalt. In the decomposition reaction of 4-NP, the appearance of galvanic pairs between cations in tetrahedral and octahedral positions is important. The photocatalytic activity in the 4-NP decomposition reaction increases in the series MnFe2O4 < NiFe2O4 < CoFe2O4, which corresponds to an increase in the intensity of the EPR spectra of ferrites.

Three-dimensional CFD modelling of a photocatalytic parallel-channel microreactor

This paper presents the estimation of adsorption rate and apparent kinetic rate constants for photodegradation of 4-nitrophenol in a recirculating and single-pass photocatalytic microreactor using simulated solar radiation. The effect of changing initial concentration (Co) of 4-nitrophenol in a recirculation mode was predicted by employing a dynamic transport model with kinetics (momentum and mole transports) using COMSOL Multiphysics. Adsorption and kinetic rate constants were estimated by fitting 3D model to experimental data. The estimated monolayer (m) and multilayer (n) adsorption–desorption rate constants were 1.77x104 m3 mol-1 h−1 (kads,m), 0.0252 h−1 (kdes,m), 1.77x104 m3 mol-1 h−1 (kads,n) and 0.0126 h−1 (kdes,n) respectively; and apparent kinetic constant (kapp) was 2.16 h−1. Results from the single pass model showed that a rise in Co produces an increase in initial degradation rate. Moreover, decreasing flow rate (Q), increasing microchannel length (L) and decreasing microchannel height (h) boost the overall conversion of 4-nitrophenol in solution. This work demonstrates the promising application of microreactors in heterogeneous photocatalysis as tertiary stage technology for wastewater treatment, especially for the photodegradation of recalcitrant pollutant.

Synthesis of few-layer g-C3N4 nanosheets-coated MoS2/TiO2 heterojunction photocatalysts for photo-degradation of methyl orange (MO) and 4-nitrophenol (4-NP) pollutants

A rational design of g-C3N4 incorporated MoS2/TiO2 heterojunction nanocomposites were successfully synthesized by combination of facile hydrothermal approach and solid state reaction method. The XRD results indicated that the heterojunction catalyst shows mixed phase of tetragonal anatase TiO2 and hexagonal MoS2. SEM and TEM results demonstrates that well defined individual spherical shaped morphology with sizes in the range of 20–25 nm was found in the MoS2/TiO2 heterostruture, which is uniformly decorated on the surface of the g-C3N4 nanosheets. The optimum mass ratio of g-C3N4 in TiO2-MoS2 was 5.0 wt% (denoted as CMT5). The prepared catalysts were used to photocatalytic degradation of methyl orange (MO) and 4-nitrophenol (4-NP), and the experiment results show that g-C3N4 assisted MoS2/TiO2 heterojunction composite (CMT5) displayed excellent photocatalytic activity towards MO dye such as outstanding removal efficiency (98%), high apparent constant (0.0612 min−1) and long-term stability. The enhanced photocatalytic activities of g-C3N4@MoS2/TiO2 photocatalysts are attributed to positive synergetic effect of heterostructure between g-C3N4 and MoS2/TiO2 hybrid structure, which not only enlarged spectral response and also enhanced the utilization rate of photons.

Activity in the Photodegradation of 4-Nitrophenol of a Zn,Al Hydrotalcite-Like Solid and the Derived Alumina-Supported ZnO

A Zn,Al layered double hydroxide (LDH), with the hydrotalcite structure and the mixed oxide obtained upon its calcination at 650 °C, was tested in the adsorption and photocatalytic degradation of 4-Nitrophenol in aqueous solution. The Zn,Al LDH was fast and easily obtained by the coprecipitation method. Hydrothermal treatment under microwave irradiation was applied to compare the effect of the ageing treatment on the photocatalytic behavior. The efficiency of the synthetized solids was compared to that of a commercial ZnO. The ageing treatment did not improve the performance of the original samples in the degradation of 4-nitrophenol. The activity of the synthetized solids tested exceeded that observed for the reaction with commercial ZnO. The photocatalytic performance of the original non-calcined hydrotalcite is similar to that of commercial ZnO. The calcined hydrotalcite showed a better performance in the adsorption-degradation of the contaminant than ZnO, and its reusability would be possible as it recovered the hydrotalcite-like structure during the reaction.

Design, syntheses, spectroscopic, aggregation properties of novel peripheral octa-substituted zinc(II), magnesium(II) and lead(II) phthalocyanines and investigation of their photocatalytic properties on the photooxidation of 4-nitrophenol

In the present paper, the syntheses, spectroscopic characterization, aggregation behaviours and photocatalytic properties of phthalocyanine compounds were searched. Octa-substituted phthalocyanines (ZnII (Pc-Zn), MgII (Pc-Mg) and PbII (Pc-Pb)) with eight peripheral (E)-3-(3-hydroxyphenyl)-1-(2,4,5-trimethoxyphenyl)prop-2-en-1-one groups were synthesized by cyclotetramerization. The spectral properties of these compounds were carried out that used widespread spectroscopic techniques. Later on, aggregation properties of synthesized phthalocyanines were examined in polar and apolar solvents. In addition to this, the photocatalytic activities of new synthesized metallophthalocyanines containing various central metal ions (zinc (II), magnesium (II) and lead (II)) were investigated. Three different metal centered phthalocyanines have been prepared for the photodegradation of 4-nitrophenol. In the photodegradation reactions that carried out in the photoreactor for 1 h without using any oxidant, 4-nitrophenol compound was completed with 90% (for PbII (Pc-Pb)), 56% (for ZnII (Pc-Zn)) and 12% (for MgII (Pc-Mg)) conversion from toxic species to non-harmful species and unknown intermediates. The turnover numbers were determined as 1500 for PbII (Pc-Pb), 933 for ZnII (Pc-Zn).

Light driven photodegradation of 4-nitrophenol with novel Co and Cu phthalocyanine in aqueous media

In this work, we have used two different metal centered water soluble phthalocyanines for the degradation of 4-nitrophenol in water media. In the photodegradation reactions that took place in the photoreactor for 1 h without using any oxidant, 4-nitrophenol compound was completed with 95% (for CoPc) and 97% (for CuPc) conversion to toxic and non-harmful species. The hydroquinone compound was identified as the main product and the benzoquinone compound as the by-product. The turnover number for Cu phthalocyanine was 1896 and for Co phthalocyanine was 2101. Finally, recovery studies were carried out for water soluble Cu phthalocyanine used as photocatalyst and the number of cycles was determined as 7.