Photocatalyst For Degradation Of Phenol Research Articles

A Facile Synthesis of Photocatalytic Fe(OH)3 Nanoparticles for Degradation of Phenol

AbstractIron hydroxide (Fe(OH)3) nanoparticles have garnered considerable attention for their effectiveness in water treatment. This paper reviews recent studies on the photocatalytic degradation of phenol using Fe(OH)3, detailing the synthesis procedure, photocatalytic reaction conditions under UV‐C and catalyst amount optimization. Iron hydroxide was synthesized using a facile precipitation method, and the produced catalyst was thoroughly characterized using XRD, FTIR, UV‐DRS, DTA/TGA and SEM. Characterization results indicated that the catalyst exhibited very low crystallinity, a 1.84 eV band gap, and very small particle sizes. The study investigated the degradation performance of phenol for different amounts of iron hydroxide, ranging from 0.1 g to 1 g, and determined the optimum catalyst amount to be 0.7 g. The catalyst demonstrated a degradation efficiency for phenol exceeding 90 % at the end of a 180 minute photocatalytic reaction. The paper offers a comprehensive analysis of Fe(OH)3 as a photocatalyst for phenol degradation, highlighting its potential for future applications in water treatment.

Visible light photocatalysis: efficient Z-scheme LaFeO3/g-C3N4/ZnO photocatalyst for phenol degradation.

In this work, a Z-scheme LaFeO3/g-C3N4/ZnO heterojunction photocatalyst with large specific surface (68.758 m2/g) and low cost (0.00035 times the cost of per gram of Au) was easily synthesized by glucose-assisted hydrothermal method. The structure, surface morphology, and optical properties of the photocatalyst were investigated. The constructed Z-scheme heterojunction catalysts can enhance the visible light absorption and carrier separation efficiency. Among these photocatalysts, the 10%-LaFeO3/g-C3N4/ZnO composite possesses the premium performance for efficient degrading 97.43% of phenol within 120 min. Even after 5 cycles, it still sustains an excellent photocatalytic stability (92.13% phenol degradation). According to the XPS surface states and the capture of active species on LaFeO3/g-C3N4/ZnO, the electrons would be transferred from ZnO and LaFeO3 to g-C3N4. In addition, ·OH plays an important role in photocatalytic reactions for phenol degradation. Thus, the proposed possible photocatalytic reaction mechanism of Z-scheme LaFeO3/g-C3N4/ZnO can provide a more economical and efficient conception for phenol degradation.

The Auto-Combustion Method Synthesized Eu2O3- ZnO Nanostructured Composites for Electronic and Photocatalytic Applications.

An efficient and environmentally friendly combustion technique was employed to produce ZnO nanopowders with different Eu concentrations (from 0.001 g to 5 g). The structural morphology of the Eu2O3-ZnO nanocomposites was examined using XRD, SEM, and infrared spectroscopy (FT-IR). In addition, UV-Vis diffuse reflectance spectroscopy was also used to investigate the effects of europium (Eu) dopant on the optical behaviors and energy bandgaps of nano-complex oxides. The photocatalytic degradation efficiency of phenol and methylene blue was investigated using all the prepared Eu2O3-ZnO nanostructured samples. Photocatalytic effectiveness increased when europium (Eu) doping ratios increased. After adding moderate Eu, more hydroxyl radicals were generated over ZnO. The best photocatalyst for phenol degradation was 1 percent Eu2O3-ZnO, while it was 0.5 percent Eu2O3-ZnO for methylene blue solutions. The obtained Eu2O3-doped ZnO nanostructured materials are considered innovative, promising candidates for a wide range of nano-applications, including biomedical and photocatalytic degradation of organic dyes and phenol.

The Greener Side of Polyoxometalate: As an Efficient Photocatalyst for Degradation of Phenol from Contaminated Water Source

The increasing amount of hazardous micro-pollutants in the aqueous environment has recently become a concern, especially because they are not usually included in environmental monitoring programs. Phenolic compounds, the most common toxic environmental pollutants, discharged as waste water from many industries are required to be removed. Usually phenolic wastes are treated by physicochemical methods like adsorption, reverse osmosis, electrolytic oxidation, and bioremediation. These methods are impractical due to high costs and the production of other toxic end products, e.g. conversion of phenol into chlorophenol when chlorination is used. Among various techniques available for removing phenol, biological treatment has been proved to be very effective. Again biological degradation usually takes longer time. Investigation of alternative economically viable pathways is the prime objective of our research work. Here we have examined the photocatalytic degradation of phenol from laboratory samples and petrochemical industries waste water under UV radiation by using nanoparticles of titanium dioxide embedded in polyoxometalates (POM). In this article, Lacunary Keggin heteropolyoxometalate H4[PVMo11O40] supported on TiO2 nanoparticles was prepared by the solvothermal method. Characteristics of nano particles studded Keggin structure in the nano composites were confirmed by FT-IR and XRD analyses. The detailed information of POM-decorated nanoparticles is obtained by the combined use of scanning and transmission electron microscopy (SEM &TEM) along with thermo gravimetric analysis (TGA). The photocatalytic activity of prepared H4 [PVMo11O40] / TiO2 for degradation of phenol under UV light was investigated using H2O2 as an oxidant. The results indicated that synthesized nano photocatalyst could be considered as an effective economic tool in the removal of organic pollutants from aqueous solutions in future.

Cyanamide-Modified Iron(III) Oxide Photocatalysts for Degradation of Phenol in the Presence of Urea and Formaldehyde

Cyanamide as the source of carbon and nitrogen was used to modify iron(III) oxide (Fe2O3) photocatalyst. While X-ray diffraction (XRD) patterns confirmed that the cyanamide-modified Fe2O3 photocatalysts have comparable crystallinity to that of the unmodified Fe2O3, the diffuse reflectance ultraviolet-visible (DR UV-vis) spectra obviously showed additional light absorption around 500-800 nm on the cyanamide-modified Fe2O3, resulting in a better absorption capability under visible light irradiation. The presence of cyanamide modifier decreased the fluorescence emission intensity of Fe2O3, implying the reduced electron-hole recombination on the Fe2O3 and/or blocked emission sites by the modifier. The presence of carbon and nitrogen on the modified Fe2O3 photocatalysts was confirmed by the elemental analyzer. Photocatalytic activities of Fe2O3 and cyanamide-modified Fe2O3 were then evaluated for degradation of phenol under UV and visible light irradiation. Modification of Fe2O3 with cyanamide significantly improved the degradation of phenol from 30 to 75% under UV light irradiation and from 0 to 80% under visible light irradiation. Photocatalytic degradation of phenol was also investigated in the presence of urea or formaldehyde or both urea and formaldehyde. Even though the percentage of phenol degradation decreased in the presence of other pollutants, it was demonstrated that cyanamide modified iron(III) oxide photocatalysts still gave good activity towards degradation of phenol even in the presence of other organic pollutants.

Preparation of a coated ZH-scheme (SnS2@CdS)/TiO2(0 0 1) photocatalyst for phenol degradation with simultaneous Cr(VI) conversion

The construction of highly efficient and multifunctional composite photocatalysts has attracted extensive attention in the field of environmental governance. In this study, an efficient coated ZH-scheme (SnS2@CdS)/TiO2(001) photocatalyst is resoundingly prepared by hydrothermal, isoelectric point and continuous ion layer adsorption reaction methods and a sequence of characterizations are carried out. The photocatalytic activity of (SnS2@CdS)/TiO2(001) photocatalyst is evaluated via degradation of phenol with simultaneous conversion of Cr(VI) under sunlight irradiation. Furthermore, the effects of initial concentrations of phenol and Cr(VI), variety of photocatalyst, solution pH, (SnS2@CdS)/TiO2(001) photocatalyst dosage and recyclingtimes on phenol degradation and Cr(VI) conversion are investigated. The crucial active species of phenol degradation are explored by capture experiments. When the coated ZH-scheme (SnS2@CdS)/TiO2(001) photocatalyst dosage is 1.0 g/L, phenol and Cr(VI) concentrations are 20 mg/L and 40 mg/L, respectively and solution pH is 4.0, the phenol degradation rate and the Cr(VI) conversion rate could reach 85.52 % and 95.69 %, respectively. Additionally, the possiblephotocatalyticmechanism of phenol degradation with synchronous Cr(VI) conversion caused by (SnS2@CdS)/TiO2(001) photocatalyst is proposed. It can be hoped that this work will provide a feasible way to treat high concentrations of organic pollutants and simultaneously convert heavy metal ions.

Lacunary Keggin-type hetero polyoxometalate, K7PMo2W9O39, supported on nano ZnO as an efficient Photocatalyst for degradation of phenol in water solution

In the present research, Lacunary Keggin-type heteropolyoxometalate, (K7PMo2W9O39) supported on ZnO nanoparticles was prepared by the impregnation method. Nanoparticle characteristics and the remaining Keggin structure in the nanocomposites were confirmed by FTIR and XRD analyses. The photocatalytic activity of prepared K7PMo2W9O39/ZnO for degradation of phenol under UV light was investigated. H2O2 was used as oxidant in the photocatalytic degradation process of phenol. The results indicated that synthesized nanophotocatalyst could be considered an appropriate heterogonous photocatalyst in the removing of organic pollutant from aqueous solutions and heterogenization of Lacunary Keggin-type heteropolyoxometalate on ZnO nanoparticles resulted in the improved light absorption intensity and decreased band gap of nanocomposites. Degradation of phenol in the presence of the K7PMo2W9O39/ZnO could lead to the disappearance approximately 93% of phenol after 60 min. But degradation for the same experiment performed in the presence of the K7PMo2W9O39 or /ZnO was less than 60% in the same time.

Visible‐light driven photodegradation of phenol over niobium oxide‐loaded fibrous silica titania composite catalyst

AbstractBACKGROUNDHeterogeneous photocatalysis has been demonstrated to be a promising alternative to treating emerging pollutants in wastewater. Phenol, an extremely toxic substance among existing pollutants, can cause long‐term unintended effects when improperly disposed. An effective measure to address this problem is to develop suitable heterojunctions. Among various photocatalyst, titanium dioxide (TiO2) appears to be an excellent photocatalyst in the degradation of organic pollutants.RESULTSSynthetization of well‐constructed heterojunction composite of niobium oxide (Nb2O5) and fibrous silica titania (FST) for enhanced photocatalytic degradation of phenol has been investigated. The photocatalytic performance demonstrated that 5 wt% Nb2O5 loaded on FST (5 Nb/FST) gave the maximum phenol degradation rate (1.70 × 10−2 mM min−1) of 10 mg L−1 phenol at pH 5 using 1000 mg L−1 catalyst within 180 min. Meanwhile, under the same conditions, 1 Nb/FST, FST, 10 Nb/FST and Nb2O5 only delivered 1.51 × 10−2, 1.30 × 10−2, 1.01 × 10−2 and 0.07 × 10−2 mM min−1, respectively. Further phenol photocatalytic degradation routes by 5 Nb/FST reveal that the main intermediates detected are hydroquinone, catechol, maleic, fumaric, and malonic acid.CONCLUSIONIn this work, 5 Nb2O5/FST composite, as an effective‐performance photocatalyst for phenol degradation, was well‐constructed. The advanced activity can primarily be attributed to the regulated Nb2O5 loading with FST and the effect of Nb/FST microsphere heterojunctions, synergistically. Besides, larger crystallite size, high impurity levels and Si‐O‐Nb and Nb–O–Ti bonds, offers excellent phenol degradation. © 2020 Society of Chemical Industry (SCI)

Ordered mesoporous La–Co–Ce–O3 through nanocasting: an effective catalyst for the photodegradation of phenol

The design of highly active photocatalysts for degradation of phenol can be particularly challenging for solar energy utilisation. Herein, a series of mesoporousLaCo1−xCexO3catalysts have been synthesised and studied for degradation of phenol under UV irradiation. Compared with LaCoO3-SG catalyst which is formed through sol-gel method, optimised LaCo1−xCexO3-NC prepared by nanocasting method showed remarkably higher activity for the degradation of phenol due to the higher specific surface area, and the order of degradation rates is LaCo0.85Ce0.15O3-NC > LaCoO3-NC > LaCoO3-SG. Moreover, Au/LaCo1−xCexO3 catalysts were synthesized via Au deposition–precipitation method, and the catalytic activity for photodegradation of phenol increased with the loading of Au on the support.

A novel synthesis of forest like BiFeO3 thin film: Photo-electrochemical studies and its application as a photocatalyst for phenol degradation

Forest-like BiFeO3 film formed through electrophoretic deposition of a prepared sol over stainless steel mesh, for the first time. The resultant film characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) combined with energy-dispersive X-ray spectroscopy (EDS), atomic force microscopy (AFM) and magnetic force microscopy (MFM). The photo-electrochemical studies show that the current and open circuit potential moved to positive values under visible light. This explained by the fact that BiFeO3 film generates photo-induced electrons and produce photocurrent and photovoltage. Finally, as prepared thin film used for photocatalytic degradation of phenol in a photocatalytic reactor. The morphology has a significant role on the photocatalytic efficiency due to enhance light-harvesting feature and provide multi scattering centers. Forest-like film was included nano-branches with diameter of 100–150 nm that offer pathways to facilitate electron transfer to substrate. In photocatalytic studies, the effect of important parameters such as initial phenol concentration, addition of H2O2, and rotating speed investigated on the photocatalytic efficiency.

Regeneration Studies of TiO2 Photocatalyst for Degradation of Phenol in a Batch System

Abstract Metal oxide such as zinc oxide and titanium dioxide can be used in many applications in the industries especially in wastewater management part. Along the time, different methods and procedures have been developed to synthesize the metal oxide according to the production demands. One of the ideas is to combine the metal oxide with biological substances come from plants and microorganisms to obtain a better performing catalyst. This study discusses regarding the potential of titanium dioxide synthesize with the help of crude extract obtained from hibiscus leaf using an electrochemical method. The catalytic performances regarding the reusability between the biosynthesis catalyst with a bare titanium dioxide photocatalyst were compared. The experimental results showed the rate of degradation favored to the catalysts involved with the crude extract than the bare one. The presence of crude extract helped to change the surface area of the catalyst hence increasing the performance and stability rate of the synthesized catalysts towards phenol degradation.

Preparation, evaluations and operating conditions optimization of nano TiO2 over graphene based materials as the photocatalyst for degradation of phenol

The preparation of the TiO2@graphene nanocomposites is significant due to its applications in the various industries such as sensor and catalytic purposes. In this study, the TiO2 and graphene-based nanocomposites have been synthesized via a simple one-step hydrothermal procedure by use of two precursors for graphene in water and ethanol as the solvents. Our fabricated photocatalysts are eco-friendly and can be recovered easily. Besides, a comparative study between graphene (GR) and graphene oxide (GO) as the graphene precursors for the photocatalytic degradation of phenol was performed. The obtained TiO2 and graphene-based nanocomposites were characterized by XRD, FESEM, EDX, FTIR, BET, NH3-TPD, PL, Raman, EDS and TGA techniques. In addition, the central composite design coupled with the response surface methodology by the Design Expert software was employed to design the experiments, optimization, and modeling of phenol decomposition. The influences of the process variables including the; solution pH, initial phenol concentration and photocatalyst amount on phenol degradation were investigated by the response surface method. In order to examine the provided model, an analysis of variance was performed for linear and quadratic equations for GO and GR-based photocatalysts in which satisfy the statistical criteria. The titanium-graphene nanocomposites has been demonstrated more photocatalytic performance than bare TiO2. It was found that a strong coupling between TiO2 nanoparticles and graphene sheets was formed. As compared with the pristine TiO2, the photocatalytic performance of the selected GO-based catalyst improved about 28% and GR-based photocatalyst increased about 15% for degradation of phenol. The empirical model and optimum conditions for the phenol degradation were obtained. Moreover, the as-synthesized photocatalysts can be recovered easily and reuse several times through the phenol degradation.

Highly efficient zinc oxide-carbon nitride composite photocatalysts for degradation of phenol under UV and visible light irradiation

In order to utilize solar light in an efficient way, a good photocatalyst shall absorb both UV and visible light. In this study, a series of composite photocatalyst consisting of zinc oxide (ZnO) and carbon nitride (CN) was successfully prepared through a physical mixing method. The ZnO is an ultraviolet (UV)-based photocatalyst, while the CN is known as a visible light-driven photocatalyst. The effect of zinc to carbon mol ratio (Zn/C) towards the properties and photocatalytic activities was investigated. X-ray diffraction (XRD) patterns revealed that the prepared ZnO-CN composite photocatalysts composed of wurtzite ZnO and graphitic CN. The presence of ZnO and CN made the composites have absorption at both UV and visible region, suggesting the potential application as photocatalysts under both UV and visible light. Fluorescence studies revealed that all ZnO-CN composites showed emission peaks at 445 and 460 nm when excited at 273 nm, but with lower intensity as compared to those of the CN. The lower emission intensity suggested the role of ZnO to reduce the charge recombination and improve the charge separation on the CN. The ZnO-CN composites were further evaluated for photocatalytic degradation of phenol. The amount of degraded phenol was determined by a gas chromatography, in which a flame ionization detector was used in this study (GC-FID). The composite photocatalyst with an optimum content of 1% Zn/C gave almost 1.15 times higher activity than the CN under visible light irradiation. On the other hand, the composite photocatalyst with an optimum content of 50% Zn/C showed 2.6 times higher activity than the CN under UV light. The improved photocatalytic efficiency on the ZnO-CN composite photocatalysts was caused by the synergic effect between ZnO and CN. The ZnO would boost the separation efficiency of photogenerated electrons on the CN, while the CN would enable ZnO to absorb visible light region as the ZnO-CN composites.

Tungsten-doped TiO2/reduced Graphene Oxide nano-composite photocatalyst for degradation of phenol: A system to reduce surface and bulk electron-hole recombination

Recombination of photogenerated charges is the main factor affecting the photocatalytic activity of TiO2. Here, we report a combined strategy of suppressing both the bulk as well as the surface recombination processes by doping TiO2 with tungsten and forming a nanocomposite with reduced graphene oxide (rGO), respectively. Sol-gel method was used to dope and optimize the concentration of W in TiO2 powder. UV-Vis, XPS, PL and time resolved PL spectra along with DFT calculations indicate that W6+ in TiO2 lattice creates an impurity level just below the conduction band of TiO2 to act as a trapping site of electrons, which causes to improve the lifetime of the photo-generated charges. Maximum reduction in the PL intensity and the improvement in charge carrier lifetime was observed for TiO2 doped with 1 at.% W (1W-TiO2), which also displayed the highest photo-activity for the degradation of p-nitro phenol pollutant in water. Tuning of rGO/TiO2 ratio (weight) disclosed that the highest activity can be achieved with the composite formed by taking equal amounts of TiO2 and rGO (1:1), in which the strong interaction between TiO2 and rGO causes an effective charge transfer via bonds formed near the interface as indicated by XPS. Both these optimized concentrations were utilized to form the composite rGO/1W-TiO2, which showed the highest activity in photo-degradation of p-nitro phenol (87%) as compared to rGO/TiO2 (42%), 1W-TiO2 (62%) and pure TiO2 (29%) in 180 min. XPS and PL results revealed that in the present nanocomposite, tungsten species traps the excited electron to reduce the interband recombination in the bulk, while the interaction between TiO2 and rGO creates a channel for fast transfer of excited electrons towards the latter before being recombined on the surface defect sites.

Tin dioxide as a photocatalyst for water treatment: A review

Abstract Many phenols, phthalates and other toxins are released into the environment from industrial or agricultural processes, or household waste. These compounds are often stable and difficult to degrade in wastewater facilities, thus posing a serious long-time risk. The development of novel and efficient technologies for the environmentally sustainable removal of these dangerous compounds from different sources is of crucial importance. The photocatalytic oxidation of organic pollutants in the presence of semiconductors such as tin(IV) oxide (SnO 2 ) is a green technology and seems to be a highly promising technique for water treatment and for the removal of recalcitrant compounds. The photocatalytic efficiency of SnO 2 can be enhanced via modifications in the design of the metal oxide, resulting in a lower recombination rate of electron–hole pairs and an increase in the efficiency of the semiconductor during the excitation state, which allows the degradation process of toxins to proceed under UV or visible light irradiation. This review article summarizes some of the most relevant investigations and fundamental aspects related to SnO 2 and its activity and discusses recent achievements in the modification of SnO 2 as a photocatalyst for phenol degradation.

Enhanced Photodegradation of Phenol by ZnO Nanoparticles Synthesized through Sol-gel Method

Zinc oxide (ZnO) utilization in advanced oxidation process (AOP) via solar-photocatalytic process was a promising method for alternative treating wastewater containing phenol. The ZnO photocatalyst semiconductor was synthesized by sol-gel method. The morphology of the ZnO nanostructures was observed by using scanning electron microscope (SEM) and the crystallite phase of the ZnO was confirmed by x-ray diffraction (XRD). The objective of this study was to synthesis ZnO nanoparticles through a sol-gel method for application as a photocatalyst in the photodegradation of phenol under solar light irradiation. The photodegradation rate of phenol increased with the increasing of ZnO loading from 0.2 until 1.0 g. Only 2 h were required for synthesized ZnO to fully degrade the phenol. The synthesized ZnO are capable to totally degrade high initial concentration up until 45 mg L-1 within 6 h of reaction time. The photodegradation of phenol by ZnO are most favoured under the acidic condition (pH3) where the 100% removal achieved after 2 h of reaction. The mineralization of phenol was monitored through chemical oxygen demand (COD) reduction and 92.6% or removal was achieved. This study distinctly utilized natural sunlight as the sole sources of irradiation which safe, inexpensive; to initiate the photocatalyst for degradation of phenol.

Solar Light Driven Nanostructured Fe and Cu Doped TiO<SUB>2</SUB> Photocatalyst for Degradation of Phenol

Solar Light Driven Nanostructured Fe and Cu Doped TiO<SUB>2</SUB> Photocatalyst for Degradation of Phenol

Photocatalytic degradation of phenol using Ag core-TiO2 shell (Ag@TiO2) nanoparticles under UV light irradiation

Ag@TiO2 nanoparticles were synthesized by one pot synthesis method with postcalcination. These nanoparticles were tested for their photocatalytic efficacies in degradation of phenol both in free and immobilized forms under UV light irradiation through batch experiments. Ag@TiO2 nanoparticles were found to be the effective photocatalysts for degradation of phenol. The effects of factors such as pH, initial phenol concentration, and catalyst loading on phenol degradation were evaluated, and these factors were found to influence the process efficiency. The optimum values of these factors were determined to maximize the phenol degradation. The efficacy of the nanoparticles immobilized on cellulose acetate film was inferior to that of free nanoparticles in UV photocatalysis due to light penetration problem and diffusional limitations. The performance of fluidized bed photocatalytic reactor operated under batch with recycle mode was evaluated for UV photocatalysis with immobilized Ag@TiO2 nanoparticles. In the fluidized bed reactor, the percentage degradation of phenol was found to increase with the increase in catalyst loading.

Photocatalytic Degradation of Phenol by Impure BiFeO<sub>3</sub> under Visible Light Irradiation

Impure BiFeO3 as a visible light photocatalyst for phenol degradation was synthezied via solid state method. The calcined temperatures of catalysts were studied. The characteristics of the catalysts were determined by XRD, SEM/EDS and BET. The catalysts were mainly composed of rhombohedral distorted perovskite-type BiFeO3 phase with impurity phases (B2Fe4O9, Bi25FeO40 and Bi2O3). Photocatalytic activity of phenol (5 mg/l) was studied in the impure BiFeO3 illuminated with 200 w fluorescence lamps. The catalyst amount and initial pH value of phenol solution on the photocatalytic effiency have been also investigated. In the present experiments, the catalyst calcined at 800°C shows the highest activity. The optimum loading of impure BiFeO3 and pH value were obtained to be 0.5 g/l and 6, respectively.

Ag3PO4sunlight-induced photocatalyst for degradation of phenol

Micrometric particles of Ag3PO4 were prepared by a simple precipitation method, and the as-prepared material was characterized by X-ray diffraction (XRD), field-emission scanning electron microscopy (FEG-SEM), nitrogen sorption isotherms, Raman spectroscopy and UV-visible diffuse reflectance spectrophotometry. Ag3PO4 particles showed excellent catalytic activity for degradation of phenol using simulated sunlight irradiation (Xenon lamp). After one hour of treatment, approximately 75% of phenol was completely mineralized. Additional experiments were conducted in order to evaluate the influence of dissolved oxygen in the photocatalytic process. During photodegradation assisted by Ag3PO4, it was considered that oxygen production and phenol oxidation were competitive processes.