Photocatalytic Degradation Of P-nitrophenol Research Articles

Photocatalytic degradation of p-nitrophenol using carbon microspheres loading Cu0 activation of peroxymonosulfate

Photocatalytic degradation of p-nitrophenol using carbon microspheres loading Cu0 activation of peroxymonosulfate

Influence of crystallographic facet orientations of sol-gel ZnO on the photocatalytic degradation of p-nitrophenol in water

Influence of crystallographic facet orientations of sol-gel ZnO on the photocatalytic degradation of p-nitrophenol in water

Synthesis of iron oxide nanoparticles encapsulated poly(styrene‐co‐4‐vinyl pyridine) nanocomposites for column adsorption and photocatalytic degradation of para nitrophenol from water

AbstractStyrene (St), 1,4 vinyl pyridine (4VP) monomers and divinyl benzene (DVB) monomer‐cum‐crosslinker at different molar ratios were subjected to emulsion polymerization in the presence of FeCl2, 6H2O/FeCl3⋅4H2O followed by the treatment with an aqueous ammonia solution to produce several iron oxide nanoparticles (IONs) impregnated crosslinked copolymer composites. The resulting polymer metal nanocomposites (PMNCs) were characterized by FTIR, proton and 13C NMR, UV–visible spectroscopy, XRD, XPS, DLS, magnetic properties, SEM and TEM. The PMNCs were used for batch and column adsorption and photocatalytic degradation of p‐nitrophenol (PNP) from water. The PMNC4 composite prepared with an styrene:4VP molar ratio of 5:1 (16.7 mol% 4VP), 4 wt.% DVB crosslinker and 0.025/0.05 molar ratios of Fe(II)/Fe(III) salts leads to an optimum batch equilibrium adsorption (qe, mg/g)/removal% of 496.36/99.3 PNP from aqueous PNP of concentration 100 mg/L. The same composite showed an equilibrium PNP adsorption (qe) of 114.2 mg/g polymer and a removal% of 26.8 for an inlet feed concentration (Ci, mg/L)/flow rate (Qt, mL/min)/bed height (h, mm) of 100/30/30 in a fixed bed. The PMNC4 polymer showed a photodegradation efficiency of 98% with a 1st order rate constant of 0.029 min−1 after 70 min of degradation of 100 mg/L PNP in solar light.Highlights Copolymer network of styrene, 4 vinyl pyridine and DVB were synthesized. Iron oxide nanoparticles were introduced into the network in‐situ during synthesis. The metal polymer nanocomposites (PMNCs) were characterized. Synthesis parameters were optimized with respect to batch adsorption of PNP. PMNCs showed excellent fixed bed adsorption and photocatalytic degradation of PNP.

Green synthesis of silver nano-catalyst using ionic liquid and their photocatalytic application to the reduction of p-nitrophenol

Ionic liquids (ILs) carrying special properties can act as electronic as well as steric stabilisers by preventing nanoparticle (NP) growth and NP aggregation. The effect of visible light on the catalytic properties of silver nanoparticles is a hot topic of extensive research nowadays. The present report demonstrates the current developments in the green synthesis of silver nanoparticles in ionic liquids and a detailed study of the room-temperature catalytic and photocatalytic reduction of p-nitrophenol (PNP) to p-aminophenol (AP). The Ag nanoparticles (AgNPs) functionalised by ionic liquids are prepared in the 40-140 nm range and are found to be spherical in shape. The photocatalytic properties of these nanocomposites for the reduction of PNP to AP were studied. Photocatalytic degradation of PNP was also analysed by these composite nanostructures. The plasmonic photocatalytic properties of the synthesised AgNPs revealed activity significantly higher than that of the room-temperature catalysis. Density functional theory calculations showed that strong interactions exist between nanoclusters and ILs. Natural bond orbital analysis showed that IL also activates the nanoparticles for further photocatalytic reduction by transferring electron transfer from the donor (IL) to the acceptor (Ag cluster) and activating the silver NPs for further catalytic reaction. Photocatalytic degradation of PNP (reduction of PNP to AP) using NP in the absence of light follows first-order kinetics, whereas in the presence of light it follows zero-order reaction kinetics.

Performance comparison of photocatalysts for degradation of organic pollutants using experimental studies supported with DFT and fundamental characterization

The effect of different metal supported TiO2 catalysts on the photocatalytic degradation of p-Nitrophenol (PNP) was investigated experimentally and supported by Density Functional Theory (DFT) approach. Process optimization studies were carried out using the best performing catalyst and the effect of different electron acceptors was also investigated. Degradation was strongly influenced by operating parameters and oxidants with efficacy as H2O2 > K2S2O8 > air. DFT simulations confirmed higher electrostatic potential in presence of hydroxyl radicals explaining the higher degradation. Overall, this work clearly establishes the effectiveness of electron acceptors in maximizing PNP degradation and explains the interaction of organic pollutants with different radicals.

Modification of polyacrylonitrile-based activated carbon fibers and their p-nitrophenol adsorption and degradation properties

Activated carbon fibers (ACFs) are widely used adsorbent materials for wastewater treatment. In this study, polyacrylonitrile-based ACFs (PAN–ACF) were modified with oxalic acid to promote their adsorption of p-nitrophenol (PNP) in wastewater. The obtained results revealed that the adsorption efficiency of the modified ACFs amounted to 98.05%. The photocatalytic degradation of PNP by ACFs loaded with nano-TiO2 and nano-ZnO photocatalysts was examined as well; under ultraviolet (UV) light irradiation, their PNP removal rates reached 99.85% and 98.31%, respectively. Moreover, the effects of pH, PNP concentration, and catalyst concentration on the PNP adsorption efficiency were systematically investigated. By conducting kinetic studies, it was found that the PNP adsorption on the PAN–ACF surface followed a pseudo-first-order model, while the PAN–ACF/TiO2 and PAN–ACF/ZnO obeyed a pseudo-second-order model, and all samples followed the Langmuir adsorption isotherm. Additionally, an integrated high-pressure microwave reactor was designed and fabricated, and the possibility of degrading PNP through the microwave-assisted catalytic oxidation by PAN–ACF/TiO2 was considered. The results of this work suggest that the novel modified PAN–ACF, PAN–ACF/TiO2 and PAN–ACF/ZnO adsorbents are promising materials for the removal of PNP-based pollutants from wastewater due to their facile application procedure, low fabrication costs, and good scale-up abilities.

Photocatalytic degradation of p-nitrophenol using biologically synthesized ZnO nanoparticles.

The present work deals with the photocatalytic degradation of p-nitrophenol as it is a United States Environmental Protection Agency-listed priority pollutant and has adverse environmental and health effects. To eradicate the detrimental environmental impact of p-nitrophenol, the biologically synthesized ZnO nanoparticles were used as a photocatalyst. The degradation of p-nitrophenol was confirmed by decreasing the absorbance value at a characteristic wavelength of 317nm using the UV-vis spectrophotometer. Reaction parameters such as ZnO photocatalyst concentration of 0.1g/L at pH11 in the presence of H2O2 (5mM) were found to be optimum conditions for p-nitrophenol degradation. The photocatalytic degradation was slowly enhanced in the presence of H2O2 as an electron acceptor. The kinetics of nitrophenol degradation was studied, which follows the pseudo-first-order reaction. The photocatalytic degradation of p-nitrophenol was characterized by using total organic carbon, chemical oxygen demand, and high-performance liquid chromatography analyses. This method is found to be effective as it is environmentally friendly, free of toxic chemicals.

Biosynthesized silver nanoparticles using Bacillus amyloliquefaciens; Application for cytotoxicity effect on A549 cell line and photocatalytic degradation of p-nitrophenol

The present study reports the biosynthesis of silver nanoparticles (AgNPs) using Bacillus amyloliquefaciens MSR5. The cellfree supernatant of B. amyloliquefaciens acted as a stabilizing agent for the synthesis of AgNPs. The synthesized AgNPs were characterized using UV-vis spectrophotometer, PXRD, FTIR, SEM-EDX, DLS, and TEM. TEM image showed the spherical shape of the biosynthesized AgNPs and it was found to be 20-40 nm in range. In this study, the AgNPs were prepared by ultrasonic irradiation. The stability of the AgNPs was found to be -33.4 mV using zeta potential. The catalytic 4-nitrophenol (4-NP) degradation by AgNPs was examined under solar irradiation and furthermore, the effects of several degradation parameters were studied. The biosynthesized AgNPs exhibited a strong chemocatalytic action with a comprehensive degradation (98%) of 4-NP to 4-aminophenol (4-AP) using NaBH4 within 15 min. In addition, MTT assay was performed to evaluate the cytotoxicity of the biosynthesized AgNPs (10 – 200 μg). The results have shown that the AgNPs exhibited significant activity on A549 cells, which was dosedependent. The study elucidates the AgNPs synthesized using cellfree culture supernatant can be used for the elimination of hazardous pollutants from wastewater.

Performance of a multistage rotating mesh support photoreactor immobilized with TiO2 on photocatalytic degradation of PNP: Reactor construction and optimization

In this study, a novel multistage rotating mesh support photoreactor was designed and employed for investigation of photocatalytic degradation of p-Nitrophenol (PNP) in aqueous solution under UV irradiation. Electrophoretic deposition (EPD) method was applied for TiO2 immobilization on the stainless steel mesh supports and surface characterizations were carried out by XRD, SEM, and BET. Central composite design (CCD) method was employed to model and optimize the process. Based on the model prediction, maximum predicted and experimental photocatalytic degradation percent of PNP under the optimum conditions of recirculating flow rate = 6 l/min, rotational speed =76 rpm and number of TiO2 immobilized meshes = 24 were obtained to be 95.7% and 95.48%, respectively. Under the optimum condition, the effect of initial solution pH on the photocatalytic degradation process was investigated and the results indicated that the PNP degradation efficiency was enhanced by reducing the initial pH to 3.5. The reduction in TOC content under optimum condition was about 55% after 5 h. Moreover, pseudo-first-order model fitted the process kinetics perfectly.

Construction of an in-situ Fenton-like system based on a g-C3N4 composite photocatalyst.

In this study, g-C3N4/PDI/Fe (gCPF) composite material was prepared by incorporating Fe ion on the composite catalyst of g-C3N4/PDI (gCP). X-ray photoelectron spectroscopy (XPS) showed that the Fe was successfully incorporated on the pristine g-C3N4/PDI. UV-vis diffuse reflectance spectrometry (UV-vis DRS) and Photoluminescence spectral (PL) analysis confirmed the enhancement of the visible absorption band following a decline in the photoelectron/hole recombination rate with gCPF. A preparatory experiment was performed on photocatalytic degradation of p-nitrophenol (PNP) to examine the activity of gCPF. Results obtained in the radical quenching and the electron paramagnetic resonance (EPR) spectroscopic studies indicated that an in-situ Fenton-like system has been successfully established and the main reactive oxygen species (ROS) changed from O2- to both O2- and OH in the gCPF system. However, a competition toward conduction band electrons between Fe3+ and O2 caused an inhibitory effect on PNP degradation. To overcome the effect, nitrilotriacetic acid (NTA) was introduced as a reducing agent for Fe3+. Upon adding NTA, the efficiency of PNP degradation greatly enhanced from 33 to 80%. The effect of initial pH, dosage of NTA and content of dissolved O2 on PNP degradation was also studied. The photocatalytic stability was confirmed by recycling experiments.

Solution combustion synthesis of CeO2/ZnO nano-composite as a potential scaffold for detection and degradation of p-nitrophenol

Abstract CeO2/ZnO nano-composite was synthesized via solution combustion synthesis (SCS) and annealed at 500 °C. As-synthesized material was characterized in terms of field emission scanning electron microscopy (FE-SEM), energy dispersive spectroscopy (EDS), powdered X-ray diffraction (PXRD), fourier transform-infrared spectroscopy (FT-IR) and UV–visible spectroscopy. The surface properties of as-synthesized nano-composite were obtained from N2 gas BET analysis. FESEM and XRD results indicate that as-synthesized material composed of two different morphologies, i.e. distinctly distinct hexagonal nanorods and aggregated spherical–shaped nanoparticles of CeO2/ZnO nano-composite. The nanorods were estimated to be 500 ± 50 nm in length and 90–140 nm in diameter. From the photocatalytic degradation of PNP, 0.15 g of CeO2/ZnO was found to be the optimum amount for the maximum degradation p-nitrophenol (PNP) molecules in 200 min. Chemical sensing study indicated that the material was highly selective to PNP with a theoretical detection limit of 3.05 μM L−1, which is believed to be due to the formation of new sites relatively more compatible to the adsorption of PNP.

Synthesis and Characterization of Co-doped Nickel-ZnO/Polypyrrole Nano-composites, and Their Effect on Photo-catalytic Degradation of P-nitrophenol under Solar Irradiation

Synthesis and Characterization of Co-doped Nickel-ZnO/Polypyrrole Nano-composites, and Their Effect on Photo-catalytic Degradation of P-nitrophenol under Solar Irradiation

Photochemical fabrication of SnO2 dense layers on reduced graphene oxide sheets for application in photocatalytic degradation of p-Nitrophenol

A room-temperature photochemical method was introduced to fabricate SnO2-reduced graphene oxide (SnO2-rGO) composite with a new type of structure. SnO2 dense layers were directly grown on the two sides of an rGO sheet through ultraviolet light (UV) irradiation of a mixed precursor solution of SnSO4, H2SO4, and graphene oxide for 6h. The composite possessed a novel flat flake-like structure consisting of two SnO2 dense layers and an rGO sheet sandwiched in between. In contrast to most graphene-based composites, the fabricated composite was non-flexible, wrinkle-free and rGO surfaces were completely covered. The composite could be used in photocatalysis and exhibited remarkably enhanced activity in degradation of p-nitrophenol under low intensity of UV light or sunlight. The activity was more than 12 times that of pure SnO2 and considerably higher than that of other SnO2-rGO composites. The dense layer immobilized the flat structure, promoted the photocatalytic activity, and maintained the long-term stability of the composite. After preservation of more than 12 months in ambient condition, the composite showed a nearly constant activity. This photochemical method can be used to fabricate graphene-based composites with regular structure, high performance, and long-term stability.

Photocatalytic Degradation of p-Nitrophenol in Aqueous Suspension by Using Graphene/ZrO<SUB>2</SUB> Catalysts

Photocatalytic Degradation of p-Nitrophenol in Aqueous Suspension by Using Graphene/ZrO<SUB>2</SUB> Catalysts

Synthesis of graphene/Fe3O4/NiO magnetic nanocomposites and its application in photocatalytic degradation the organic pollutants in wastewater

In this paper, a new type of magnetic photocatalyst graphene/Fe3O4/NiO (GNs/Fe3O4/NiO) nanocomposites have been first synthesized by a facile route. The as-prepared products have been characterized by scanning electron microscopy, Transmission electron microscope, Fourier transform infrared spectroscopy, X-ray diffraction, thermal gravimetric analysis, vibrating sample magnetometry, energy dispersive X-ray spectroscopy. The experimental results showed that magnetic GNs/Fe3O4/NiO nanocomposites exhibited significantly enhanced magnetic and adsorption performance, and the saturation magnetization of three kinds nanocomposites GNs/Fe3O4/NiO (S1), GNs/Fe3O4/NiO (S2) and GNs/Fe3O4/NiO (S3) were about 63.07, 43.33 and 22.42 emu g−1, respectively. It was found that the composite materials has perfect photocatalytic performance for degrade p-nitrophenol and rhodamine B by analyzing its photocatalytic degradation performance. Moreover, the nanocomposites can be adsorbed and recycled by extra magnetic field after photocatalytic degradation of p-nitrophenol and rhodamine B in wastewater. Therefore, this kinds of magnetic nanocomposites may have great potential applications in photocatalytic field in the future.

Evaluation and modeling of a newly designed impinging stream photoreactor equipped with a TiO2coated fiberglass cloth

The photocatalytic degradation ofp-nitrophenol (PNP) using TiO2particles immobilized on a fiberglass cloth was investigated in a novel design of a photo-impinging stream reactor.

Photo-catalyzed p-nitrophenol degradation in aqueous dispersions of ferrihydrite and H2O2.

Nitrophenols are hazardous and toxic to living organisms. For this study, ferrihydrite was prepared to test its capabilities for p-nitrophenol degradation. A ferrihydrite particle prepared in neutral environmental conditions is sphere-like with a diameter of 2-4 nm and its total surface area is approximately 229 m2 x g(-1). The combination of ferrihydrite and trace H2O2 is effective for the degradation of p-nitrophenol under simulated sunlight irradiation. Hydroquinone, the initial intermediate of p-nitrophenol decomposition, autocatalyses the subsequent degradation of p-nitrophenol because it accelerates the photo-reductive dissolution of ferrihydrite. The effect of key operating parameters such as ferrihydrite dosage, initial solution pH and H2O2 dosage were also studied on the photocatalytic degradation of p-nitrophenol. The results indicate that the combination of 0.2 g x L(-1) ferrihydrite, 0.45 mmol x L(-1) H2O2 is highly efficient for the degradation of p-nitrophenol (0.15 mmol x L(-1)) at pH 2.5-3.0. A ferrihydrite was reused several times, still keeping its original photocatalysis.

Electrodeposition technique-dependent photoelectrochemical and photocatalytic properties of an In2S3/TiO2 nanotube array

Electrodeposition is a very versatile tool to fabricate multicomponent TiO2 nanotube array (NTA) composites. However, the understanding of the correlation between the component structure and the fabrication technique has not been clearly investigated yet, though it has been observed that the performance of composites is bound up with the component structure. In this work, the photoelectrochemical properties of In2S3-TiO2 NTA composites prepared by CV electrodeposition, potentiostatic electrodeposition and pulse electrodeposition, respectively, were investigated. The results revealed that the as-prepared photoelectrodes exhibited electrodeposition technique-dependent properties, and the pulse prepared In2S3-TiO2 yielded the highest and stable photocurrent response, consequently exhibiting a superior photocatalytic activity in the degradation of p-nitrophenol (PNP). This may be attributed to the homogeneous, ultra-fine structure of In2S3 nanoparticles (NPs), which brings about a high charge separation efficiency. Furthermore, the trapping tests showed that both radicals and holes were the main active species in the photocatalytic degradation of PNP. This work not only provided a firm basis for maximizing photocatalytic activity via tuning fabrication techniques but also gave a deep insight into the photocatalytic mechanism.

Synthesis and characterization of composite catalysts Cr/ZSM-5 and their effects toward photocatalytic degradation of p-nitrophenol

Raw rice husks (white particles) were used to produce silica through submission to consecutive chemical treatment using NaOH and HCl solutions. The prepared silica was well incorporated with other components under hydrothermal conditions to synthesize ZSM-5. Cr framework-substituted ZSM-5 with constant Si/(Cr+Al) ratios have been synthesized hydrothermally and characterized by physicochemical methods, e.g. X-ray diffraction (XRD), FT-IR, UV–vis spectroscopy and N2 adsorption. FT-IR spectroscopy of Cr-substituted ZSM-5 shows new bands at 688 and 627cm−1 due to extra framework chromium oxide. The replacement of Al3+ by Cr ion causes a shift of Si–O–T vibration to lower wave numbers with the appearence of a new band at 990cm−1 in Cr-ZSM-5 samples which can be directly correlated with the entrance of chromium ions into the framework of the ZSM-5 lattice and the presence of Cr–O–Si linkage in the structures. UV spectroscopy showed absorption bands at 263 and 381nm related to the tetrahedrally coordinated environment in the (Cr5+–O−1)∗←(O2−Cr6+) charge transfer transition state of isolated Cr(VI) atoms inside the ZSM-5 matrix.The photocatalytic activity of Cr incorporated ZSM-5 zeolite toward the degradation of p-nitrophenol (PNP) was well investigated at atmospheric pressure, 25°C, with H2O2 as an oxidizing agent. The enhanced photocatalytic activity of 0.4CrZ is attributed to charge-transfer excited complex between Cr in zeolite along with PNP ligand in addition to higher surface area and high dispersion Cr in the framework comparatively. More information on local structures of metal oxides inside zeolites and their photocatalytic activities toward PNP were deduced, correlated and discussed.

Photocatalytic degradation of p-nitrophenol by zinc oxide particles

The degradation of p-nitrophenol (PNP) by ZnO particles has been studied. With increasing PNP loading the degradation rate decreased. The mineralization of PNP was rather slow compared with the degradation. With a decrease in particle diameter or an increase in surface area, the degradation rate significantly increased. The degradation capability with solar irradiation was found to be superior to UV light irradiation. It was found that 30 mg L(-1) of PNP was completely degraded by solar light with the accumulated UV light of around 23 kJ L(-1) at ZnO dosage of 5 g L(-1). The degradation PNP by ZnO with UV light or solar light was faster than that by TiO(2).