Maximum Photocatalytic Degradation Research Articles

Innovative S-Scheme heterojunctions: Boosting methylene blue degradation and antimicrobial efficacy with Ni–CoS@S-g-C3N4

The release of waste, including organic dyes from various industries, directly into water bodies significantly contributes to environmental pollution. Consequently, there is a need for photocatalytic materials that can effectively remove harmful pollutants from water, ensuring its purity and safety. Carbon-based photocatalysts have garnered significant attention in this context because of their exceptional stability, high conductivity, and very small band gap. In the current project, a series of CoS, Ni–CoS, and Ni–CoS/S-g-C3N4 with different concentrations of S-g-C3N4 were synthesized using a simple, efficient, and cost-effective co-precipitation technique, while S-g-C3N4 was constructed through a thermal degradation process using thiourea as a precursor. The produced photocatalysts underwent characterization utilizing sophisticated analytical methods including FTIR, XRD, SEM, and EDX. The photocatalytic degradation behavior of the prepared photocatalysts was assessed using a UV–visible spectrophotometer, and the doping of Ni-metal was found to significantly enhance the degradation rate of methylene blue (MB), a standard pollutant dye in the order of CoS < %8Ni–CoS <8%Ni–CoS@50 % S-g-C3N4.the maximum photocatalytic degradation was shown by the nanocomposites (8%Ni–CoS@50 % S-g-C3N4) i.e. 94 %. The EIS spectra for CoS, 8 % Ni–CoS, and Ni–CoS/50 % SCN were analyzed, and their antimicrobial effectiveness was evaluated.

Beta-cyclodextrin–Phyllanthus emblica emulsion for zinc oxide nanoparticles: Characteristics and photocatalysis

Abstract This study presents a new approach for producing zinc oxide nanoparticles (ZnONPs) utilizing an emulsion of beta-cyclodextrin (β-CD) and Phyllanthus emblica fruit extract. When synthesized, the particles were around 90 ± 5 nm in size. The zeta potential investigation yielded a value of −27.1 mV. The generated ZnONPs exhibited 83.70% anti-oxidant activity as well as good radical scavenging capabilities. The catalytic activity of ZnONPs was investigated using rhodamine B dye, and they displayed that maximum photocatalytic degradation was found to be 90.32% when exposed to UV light and 50.5% when not exposed to UV light. The kinetic investigation of photocatalytic degradation employs pseudo-first-order rate kinetics, with a rate constant of 2.5 × 10−2 under UV irradiation and 1.1 × 10−2 without irradiation. Anti-bacterial tests against Escherichia coli bacteria demonstrated the particles’ anti-bacterial characteristics. Anti-cancer studies were carried out using KB-31 cancer cells at varying particle concentrations. The studies confirmed that the particles produced are anti-cancer. In conclusion, this study reports a new green synthesis method to fabricate ZnONPs with high anti-microbial, anti-oxidant, and anti-cancer properties and suitable for various biomedical applications.

Green synthesis of Silver-iron-zinc oxides nanocomposite via Embelia schimperia leaf extract for photo-degradation of antibiotic drug from pharmaceutical wastewater

The co-precipitation approach is used in the current study to create an environmentally friendly Ag/Fe/ZnO nanocomposites utilizing an aqueous leaf extract of Embelia schimperia. The synthesized nanocomposite was characterized using Fourier-transform infrared, UV, X-ray, UV–vis, DLS, TGA, and SEM to determine its functional group, structure, bandgap energy, size distribution, a mass of loss, and energy gain or loss, and morphological structure, respectively. The bioactive components of Embelia schimperia, synthesized Ag/Fe/ZnO NCs and degradation of Amoxicillin via photocatalyst were assessed. The response surface methodology of central composite design (CCD) was used to examine and optimize the effects of three independent variables on the degradation of Amoxicillin under visible light. According to the experimental findings, the maximum photocatalytic degradation efficiency was achieved at green synthesized Ag/Fe/ZnO NCs dosage of 100 mg, a concentration of Amoxicillin of 30 mg/L and a radiation time of 180 min. Their findings show that Embelia schimperia extract-derived Ag/Fe/ZnO nanocomposites is a promising alternative for degradation of pharmaceuticals contamination of wastewater via photocatalytic under the given conditions.

Highly Efficient Photocatalytic Degradation of Imidacloprid Based on Iron Metal-Organic Frameworks of Mesoporous NH2-MIL-88b/Graphite Carbon Nitride Nanocomposites by Visible Light Driven in Aqueous Media.

Pesticides that protect crops from insects and other pests are some of the main causes of water pollution. Imidacloprid (IMC) is the most widely used insecticide in the world and should be removed from the environment. This work aims to prepare mesoporous nanocomposites to increase the photodegradation efficiency of IMC. To improve the surface properties and enhance the photocatalytic activity, mesoporous nanocomposites with different weight ratios of graphite carbon nitride (CN = 125, 250, and 500 mg) were prepared by the solvothermal method. Mesoporous NH2-MIL-88b(Fe)/graphite carbon nitride (CN = 250 mg, NH2-MCN-2) nanocomposites showed the best photocatalytic performance. To save the time and cost of the experiments, central composite design (CCD) and response surface methodology (RSM) were used and the results were obtained as the initial concentration of IMC (20 mg L-1), amount of photocatalyst (0.76 g L-1), pH = 5, and degradation time ∼46 min. The maximum photocatalytic degradation efficiency estimated by the model was obtained at 96.31%, which is very close to the actual value of 95.47%. The mesoporous NH2-MCN-2 nanocomposite showed excellent stability and suitable reusability with a maximum degradation of 84.5% after five cycles. Results obtained from kinetic studies indicated a rate constant value of 0.08 min-1, and isotherm models showed that equilibrium data are more consistent with the Langmuir model in photocatalytic degradation. Electrochemical experiments showed significant improvement in the electron transfer rate and photocatalytic activity of the mesoporous NH2-MCN-2 nanocomposite. Different trapping agents were used to investigate the effective active species in IMC photodegradation, and it was determined that the hole (h+) and OH radical (•OH) play the main role. The possible mechanism for IMC photocatalytic degradation was suggested by Mott-Schottky (M-S) electrochemical impedance.

Structural feature, morphology and optical properties of g-C3N4 decorated CuO-Fe3O4 nano composite for electrocatalytic and photocatalytic applications

The present work, novel growth of ternary CuO-Fe3O4/g-C3N4 nanocomposites (NCs) with three different ratio (CuO-Fe3O4:g-C3N4 = 90:10; 75:25 and 50:50), binary CuO-Fe3O4 nanocomposite (NC) and its pristine g-C3N4, CuO and Fe3O4 was synthesized and characterized by XRD, SEM with EDX, TEM, Raman, XPS, UV-DRS and PL. The XRD pattern exhibited the diffraction peaks of g-C3N4 (hexagonal) and CuO (monoclinic) and Fe3O4 (FCC) and the CuO-Fe3O4 mixing of monoclinic and cubic phases along with CuO (−111) direction. The TEM analysis shows the dispersion of CuO-Fe3O4 on g-C3N4 sheets in the CuO-Fe3O4/g-C3N4 (50:50) NC. From the XPS spectra, the oxidation states of Cu2p, Fe2p, O1s, C1s, and N1s, as well as their orbital bonding, are analyzed. The bandgap was calculated by photon energy vs ILD and (F(R∞)hv)2 by using UV-DRS spectrum. The catalyst, CuO-Fe3O4/g-C3N4 (50:50)@NF had a low overpotential of 69 mV at the current density of 10 mA cm2, close to the value of 20 % Pt (45 mV). A chronoamperometry test demonstrated that CuO-Fe3O4/g-C3N4 (50:50)@NF works efficiently for more than 30 h at a high current density of 15 mA cm−2 indicating the strong stability of CuO-Fe3O4/g-C3N4 (50:50)@NF. The maximum photocatalytic degradation efficiency against Rhodamine-B was found to be 99.51 % and crystal violet degradation efficiency is 98.02 % by using CuO-Fe3O4/g-C3N4 (50:50).

Visible light-driven characterisation of AgI/CeO2/rGO nanocomposites and their application in levofloxacin degradation

AgI/CeO2/rGO complexes were prepared in different proportions and characterized by XRD, SEM, TEM, FT-IR, XPS, BET, PL, I-T and EIS. The photocatalytic degradation experiments of levofloxacin (LVF) under visible light (λmax=245 nm) was performed to determined the photocatalytic activity of the composites. When the concentration of simulated pollutants is 20 mg/L and the amount of application is 15 mg, the doping ratio is AgI/CeO2/3%-rGO, and the photocatalytic effect of the nanocomposite with pH 5 is the best. The maximum photocatalytic degradation rate of 98.02% can be achieved. The cyclic stability of the composites and the kinetics were also analyzed, and possible degradation mechanisms were also proposed. The intermediates were also detected using high performance liquid chromatography-mass spectrometry(HPLC-MS) to obtain the possible degradation process. The results show that AgI/CeO2/rGO composite exhibits good photocatalytic degradation performance under visible light, and the maximum photocatalytic degradation rate for treating pollutants containing LVF is 98.02%. These findings are expected to provide important theoretical and practical guidance for environmental treatment and research and development of photocatalytic materials.

Surface Modification of p‐type ZnO Nanorods by Nitrogen Doped SiO2 Dots as an Efficient Solar Photocatalyst for Degradation of Ciprofloxacin in Water

AbstractA simple two step hydrothermal method is developed for synthesizing p‐type zinc oxide (ZnO) nanorods surface modified with nitrogen doped silicon dioxide dots (ZnO/N‐SiO2). The structure, morphology, and chemical compositions are confirmed by X‐ray diffraction, Raman spectroscopy, Fourier transformed infrared spectroscopy, X‐ray photoelectron spectroscopy, transmission electron microscopy, and by Mott‐Schottky studies. The N‐SiO2 dots on the surface of p‐type ZnO nanorods are formed during hydrothermal treatment at 90 °C (i.e., at 363 K), named as [ZnO/N‐SiO2]363K. While N‐SiO2 dots are embedded in the ZnO nanorods of the batch synthesized at 453 K. The band gap of the batches of ZnO/N‐SiO2 are wider (3.24–3.30 eV) than the pristine ZnO (3.16 eV). The modification of ZnO nanorods by the N‐SiO2 dots is corroborated by changes in the flat band potential, revealed from Mott‐Schottky measurements. The EPR and photoluminescence studies confirm p‐type ZnO attributable to zinc vacancies (VZn). The batch [ZnO/N‐SiO2]363 exhibits maximum photocatalytic degradation of ciprofloxacin in water. The specific rate constant is k′ = 0.97 min−1 g−1, which is nearly three times higher than that exhibited by the irregularly spherical pristine ZnO nanoparticles (k′ = 0.36 min−1 g−1). The enhanced photocatalytic degradation is attributed to holes mediated hydroxyl radical generation. The degradation mechanism is proposed by carrier mobility studies, radical scavenging studies and by identifying the degradation products.

V2O5 based nanocomposites with MOF and rGO for the adsorption and photocatalytic degradation of methylene blue dye

In the present work, vanadium pentoxide-metal organic framework (V2O5-MIL 125 MOF) and vanadium pentoxide-reduced graphene oxide (V2O5-rGO) nanocomposites were successfully synthesized using a facile low-temperature hydrothermal treatment. These nanocomposites were used as photocatalysts to study the adsorption capacity and photocatalytic degradation of methylene blue (MB) dye in an aqueous solutions, under dark and UV light conditions. The influence of adsorption on dye removal and its isotherm revealed that both the nanocomposites follow the Freundlich isotherm. The kinetics of adsorption indicated pseudo-second-order behaviour. V2O5-MIL 125 MOF and V2O5-rGO exhibited maximum dye adsorption capacities of 62 and 24 mg/g, respectively. The optimal values for maximum photocatalytic degradation were determined, and the mechanism of degradation was verified using radical scavengers. A 125 W high-pressure mercury vapour light was employed as the light source for all dye degradation studies. Maximum degradation was obtained at neutral conditions (pH 7.4) of the solution, ambient temperature (30±2˚C), and an initial dye concentration of 10 ppm. The synthesized photocatalysts V2O5-MIL 125 MOF and V2O5-rGO exhibited maximum degradation of 87% within 270 min and 82% within 300 min of UV light exposure, respectively. The adsorption and photocatalytic effects of V2O5-MIL 125 MOF and V2O5-rGO were also compared with pure vanadium pentoxide (V2O5), revealing superior activity in both cases.

Study of the photocatalytic activity of clay supported TiO2 nanoparticles for methylene blue degradation.

The photocatalytic degradation of a methylene blue (MB) solution was studied using a formulation of TiO2 nanoparticles (NPs) suspended in a commercial antibacterial paint, and supported on clay strips. All experiments were carried out in a batch reactor containing a UV-C light source and the MB solution under stirring. Parameters such as catalyst mass loading, MB concentration, as well as catalyst properties were considered for the experimental procedure. The effect of the mass loading on the photocatalytic activity of the TiO2 formulations immobilized on the clay supports was evaluated using 100, 200, and 500 mg of TiO2 on 40 mL of paint, sampling the MB solution under degradation at 0, 2, 5, 10, 20, 50, 100 and 200 min. The aliquots were analyzed by optical spectroscopy in the 400-1000 range to determine the absorbance, calculate the concentration with the Beer-Lambert equation, and obtain the amount of MB degradation. The maximum photocatalytic degradation of MB for the supported photocatalyst was 52%, 55%, and 60%, respectively. For comparison, suspended TiO2 nanoparticles lead to ca. 95% of MB photodegradation in ca. 60 min. The supported photocatalysts were tested in three consecutive cycles of 200 min to study the mechanical and photocatalytic stability. The activity of the photocatalysts with mass loading of 100 and 200 mg TiO2 decreased to ca. 35% after the three cycles, while the formulation with 500 mg TiO2 remained stable for three cycles. The final samples of each cycle were characterized by XRF, discarding erosion of the material from the support.

Coal fly ash-supported ZnO-promoted TiO2 towards UV photocatalytic degradation of anthraquinone dye: Parametric optimization, kinetics and mechanism studies

Heterogeneous photocatalysis via combination of catalyst and UV irradiation is one of the most promising advanced oxidation processes for degradation of water-soluble organic contaminants. Herein, different photocatalysts (ZnO/CFA, TiO2/CFA, and TiO2-ZnO/CFA) were synthesized via sol-gel and impregnation techniques and applied for the degradation of acid blue 25 (AB25) dye in aqueous solution under UV light in a photoreactor. Various spectroscopic techniques (XRF, XRD, BET, FTIR, UV–vis DRS, TEM and EDS) were employed to evaluate the chemical structure, functional groups, textural, and optical properties of the binary and ternary composites. TiO2-ZnO/CFA displayed rapid degradation of AB25 as compared to ZnO/CFA and TiO2/CFA, owing to the dualistic photocatalytic sites. The prepared TiO2-ZnO/CFA composite was used in synergy with the photoreactor for photocatalytic degradation process optimization, and the optimum degradation conditions in relation to initial AB25 concentration (10 mg/L), UV light intensity (18 W/m2), flow rate (12.5 L/h), and irradiation time (150 min) as input parameters were determined using Taguchi design approach. The maximum photocatalytic degradation efficiency was 98.79±0.94% under those aforementioned conditions, indicating that the synergies between the photoreactor and the TiO2-ZnO/CFA photocatalyst resulted in the effective destruction of AB25 dye molecules. Furthermore, the spent photocatalyst was easily removed from the degraded solution and reused up to nine times. After 150 mins of UV irradiation with TiO2-ZnO/CFA photocatalyst, almost complete mineralization of AB25 solution was achieved.

Efficient visible light-induced photocatalytic degradation of tetracycline hydrochloride using CuFe2O4 and PANI/CuFe2O4 nanohybrids.

Tetracycline hydrochloride (TC-HCl) is widely implemented as a wide-ranging antibacterial drug in medical care and animal husbandry, in spite of having negative effects on the environment and human health. Photocatalytic treatment is one of the popular techniques used to treat TC-HCl in wastewater. In this study, we have used CuFe2O4 and CuFe2O4/polyaniline (PANI) nanohybrids as photocatalysts for the degradation of TC-HCl. The metal ferrite and its nanohybrids were synthesized by co-precipitation method. FTIR, UV-Vis, XRD, and SEM-EDX were used to characterize the synthesized nanohybrids. The optical band gaps were estimated to be 2.74 eV for CuFe2O4, 1.72 eV for 1-PANI/CuFe2O4, 1.66 eV for 3-PANI/CuFe2O4, and 1.31 eV for 5-PANI/CuFe2O4. The photocatalytic performance of the nanohybrids appeared superior than pristine CuFe2O4, and maximum photocatalytic degradation was observed to be 86% within 120 min using 5-PANI/CuFe2O4 as the photocatalyst. The degraded fragments were analyzed by LCMS technique, and a tentative mechanism for the degradation of TC-HCl was proposed.

Preparation of graphitic carbon nitride (g-C3N4) for novel dielectric and photocatalytic dye removal applications

Recent developments in 2D nanomaterials have greatly expanded their use in engineering applications. Graphitic carbon nitride (g-C3N4) shows a combination of electrical conductivity, sensing and luminescence abilities, biocompatibility, and chemical stability. The present study showcases the effectiveness of g-C3N4 as a photocatalyst for removing various organic molecules from water (such as methylene blue, 4-nitrophenol, and pharmaceutical drugs) and its potential use in dielectric applications when combined with an organic polymer (polyvinylidene fluoride; PVDF). XRD patterns confirmed the formation of g-C3N4 (which is complimented by the UV-Visible and FTIR results) and PVDF-g-C3N4 composite film. SEM-EDS verified the chemical homogeneity of the as-prepared g-C3N4 powder. Maximum photocatalytic degradation was observed for methylene blue dye (96.48%) with a half-life of 24.18 min, whereas the least degradation was detected for hydroxychloroquine (53.10%) with a half-life of 90.12 min after 120 min of UV-visible exposure. 10 wt% C3N4 reinforced PVDF thick films exhibited stable dielectric properties at low temperature (below 60°C) as compared to PVDF alone. At 1 kHz, the dielectric permittivity and tangent loss of the PVDF-g-C3N4 composites come out to be ∼6 and ∼0.05, respectively (at room temperature). The AC conductivity and activation energy of the synthesized composite was also studied.

A novel oxygen-deficient core–shell ZA@ZnO1-X nanocomposite for enhanced degradation of multiple polyaromatic hydrocarbons

Persistent organic pollutants such as polyaromatic hydrocarbons (PAHs) are one of the emerging micropollutants present in several industrial effluents. Being trace refractory organics, its treatment by conventional method is very challenging. Thus, we report a novel core–shell zeolite A@oxygen-deficient ZnO (ZA@ZnO1-X) nanocomposite for degradation of PAHs mixture containing fluorene, phenanthrene, and anthracene. The hierarchical structure helps to reduce the recombination of photogenerated electron and holes pair, thereby availing more active species for photodegradation. The enhanced photodegradation efficacy is due to the synergistic effect of oxygen-defect sites in ZA@ZnO1-X and photoactive species. Core-shell ZA@ZnO1-X shows improved catalytic properties with a band gap value of 2.65 eV lower than the sole ZnO nanosheet (3.03 eV). The porous shell of the ZnO1-X structure provides an enhanced adsorption site and fully utilizes photon energy (visible light) with no aggregation because of ZA support. The maximum photocatalytic degradation is achieved by optimizing reaction parameters of 96%, 95.1%, and 93% of fluorene (0.02436 min−1), phenanthrene (0.02421 min−1), and anthracene (0.02102 min−1), respectively in 2 h at neutral pH and catalyst load 1 g/l. The primary active species responsible for PAHs degradation is h+, followed by HO•, O2•- radicals analyzed by quenching experiment. The degradation intermediates, and degraded products analysis by GC–MS gives a plausible general reaction pathway of PAHs and reveals primary intermediate is a phthalate derivative. Finally, the regeneration of active catalytic sites in the ZA@ZnO1-X photocatalyst shows its stability and reusability over five consecutive cycles.

Removal of Food Dye Tartrazine (E102) from Aqueous Solution using ZnO and CuO-TiO2 as Photocatalysts

Tartrazine dye has a major role in food as well as in other industrial products, like cosmetics, personal care products, pharmaceutical products and many more, therefore it is the cause of many environmental pollutions particularly water pollution. Its removal from water bodies is almost impossible with traditional techniques, because of heterogeneity in its composition. This investigation was carried out to examine the photo-catalytic degradation of food dye tartrazine (E102) from its aqueous solution, using ZnO (zinc oxide) and mixed CuO-TiO2 (copper oxide-titanium dioxide) as photo-catalysts at room temperature. The influence of several parameters, such as pH of medium, time of irradiation, concentration of dye solution and amount of catalyst was investigated. Kinetic analysis was also carried out using Langmuir – Hinshelwood approach. Maximum Photo-Catalytic Degradation (PCD) of E102 was observed to be at pH 1. Similarly significant rise in the degradation of E102 was observed with the time of irradiation, concentration of dye solution and amount of catalyst. From the results obtained it was observed that ZnO and CuO-TiO2 are effective photo-catalysts for the removal of E102 from its aqueous solution. However ZnO was observed to be more effective than CuO-TiO2 in the degradation of E102 from aqueous solution.

Visible-light-enhanced photocatalytic activity of BaTiO3/γ-Al2O3 composite photocatalysts for photodegradation of tetracycline hydrochloride

A polyacrylamide gel method combined with low temperature sintering technology was developed for fabrication of BaTiO3/γ-Al2O3 composite photocatalysts, which exhibits excellent photocatalytic activity for the degradation of tetracycline hydrochloride (TC-HCl) under simulated sunlight irradiation. The effects of BaTiO3/γ-Al2O3 mass percentages, drug concentrations and pH values on the photocatalytic activity of BaTiO3/γ-Al2O3 composite photocatalysts were investigated. The optimum BaTiO3/γ-Al2O3 mass percentage, drug concentration and pH value are 5 wt%, 50 mg/L, and 6.77, respectively. The maximum photocatalytic degradation rate of BaTiO3/(5 wt%) γ-Al2O3 composite photocatalysts for the degradation of TC-HCl was approximately 16.81 times that of γ-Al2O3. The trapping experiments and reactive oxygen species production experiments proved that reactive hole and hydroxyl radical played major role in drug degradation. The photocatalytic activity enhancement of the BaTiO3/γ-Al2O3 composite photocatalysts came from the defect states in alumina and the interfacial defects between barium titanate and alumina and the high charge transfer and separation efficiency, which resulted from the type II band arrangement structure of BaTiO3/γ-Al2O3. The above results reveal that there is a significant potential application for the BaTiO3/γ-Al2O3 composite as a photocatalyst in the photo-degradation of drugs under simulated sunlight irradiation.

Copper Ferrite nanoparticles synthesised using a novel green synthesis route: Structural development and photocatalytic activity

The copper ferrite nanoparticles, recognized for their ferromagnetic characteristics, minimal conductivity, and superior electrochemical stability, were synthesized by a facile auto combustion approach using egg white as fuel via a green synthesis route. CuFe2O4 nanoparticles' structural, morphological, and optical properties were examined. XRD is used to determine the phase formation, particle size, and lattice parameter of spinel ferrite. X-ray Diffractometer (XRD), Fourier Transform Infrared Spectrometer (FTIR), Scanning Electron Microscopy (SEM), and Energy Dispersive X-ray analysis were used to rigorously examine the phase purity of the synthesized spinel ferrite. For morphological analysis, SEM and TEM were employed, whereas EDAX was used for elemental analyses. For a better knowledge of the conduction band (CB) and valence band (VB) boundaries of the produced nanoparticles, optical experiments were conducted by UV Diffuse Reflectance Spectroscopy. The degradation of Rhodamine B dye determined the photocatalytic competence of the synthesized sample under visible light. At regular intervals of time, the entire process was observed with a spectrophotometer. CuFe2O4 nanoparticles reveal a maximum photocatalytic degradation efficiency of around 94%, which is higher than that of CuFe2O4 nanoparticles prepared via other chemical route.

Photocatalytic Degradation of Dye Acid Orange Seven on Titanium Dioxide Photocatalysts Immobilized on Stainless Steel Coated Layers: Role of Catalyst Loading and Ultrasonic Treatment

Supported titanium dioxide (TiO2) was investigated for potential application in photocatalytic degradation of dye acid Orange 7 in textile wastewater. Two commercial powder photocatalysts, Degussa (P25) and Precheza (AV01), were immobilized on stainless steel plates of dimensions (75 mm × 25 mm) through Electrophoretic Deposition Process (EPD) from aqueous colloidal suspensions of n-TiO2, c=10 g.L-1 produced in methanol. Two sets of coated layers were prepared - using ultrasonically treated TiO2 colloidal suspensions and without ultrasonic treatment. The prepared coated layers were fitted onto a four-hole photocatalytic reactor operating under batch-mode conditions. As a source of UV light, Sylvania LynxS, 11W UV lamps emitting light of wavelength between 320-400 nm with maximum wavelength at λ=355 nm was used. The current study aimed to evaluate the effect of ultrasonic treatment on the catalyst’s colloidal suspension and electrophoretic deposition loading (mg/cm2) on its surface area on the resultant photocatalytic degradation of dye Acid Orange 7. The photocatalytic degradation of the dye was monitored by changes in dye absorbance for 120 minutes at an interval of 30 minutes. Changes in dye concentration were determined by ultraviolet spectrophotometry at λ = 485 nm. The initial concentration of dye Acid Orange 7 used in the experiments was c=1×10-4 mol. L-1. The findings show that 61.1 % of dye mineralization was achieved after 120 minutes of photocatalytic degradation. The optimum catalytic loading for maximum photocatalytic degradation was determined at 0.75 mg/cm2 for the two commercial powder catalysts - TiO2 (P25/AV01) in ultrasonically treated TiO2 (P25) and non-ultrasonically treated TiO2 (AV01). Ultrasonic treatment of TiO2 (P25) colloidal suspensions before immobilisation positively influenced its photocatalytic activity, whereas ultrasonic treatment negatively affected the photoactivity of TiO2 (AV01). Overall, TiO2 (AV01) proved to be more efficient by 28.6%, compared to TiO2 (P25). The results show the potential application of UV-TiO2 treatment model in the remediation of coloured dye Acid Orange textile wastewater.

Removal of tetracycline from wastewater using g-C3N4 based photocatalysts: A review

Tetracycline is currently one of the most consumed antibiotics for human therapy, veterinary purpose, and agricultural activities. Tetracycline worldwide consumption is expected to rise by about more than 30% by 2030. The persistence of tetracycline has necessitated implementing and adopting strategies to protect aquatic systems and the environment from noxious pollutants. Here, graphitic carbon nitride-based photocatalytic technology is considered because of higher visible light photocatalytic activity, low cost, and non-toxicity. Thus, this review highlights the recent progress in the photocatalytic degradation of tetracycline using g–C3N4–based photocatalysts. Additionally, properties, worldwide consumption, occurrence, and environmental impacts of tetracycline are comprehensively addressed. Studies proved the occurrence of tetracycline in all water matrices across the world with a maximum concentration of 54 μg/L. Among different g–C3N4–based materials, heterojunctions exhibited the maximum photocatalytic degradation of 100% with the reusability of 5 cycles. The photocatalytic membranes are found to be feasible due to easiness in recovery and better reusability. Limitations of g–C3N4–based wastewater treatment technology and efficient solutions are also emphasized in detail.

Polyethylene glycol capped copper ferrite porous nanostructured materials for efficient photocatalytic degradation of bromophenol blue

Three different types (blank, annealed, and functionalized) of copper ferrite nanoparticles (CuFe2O4) were synthesized by the co-precipitation method. The CuFe2O4 NPs were characterized by Fourier transform infrared (FTIR), Scanning electron microscopy (SEM), X-ray diffraction (XRD), and Energy-dispersive X-ray spectroscopy (EDX) techniques. FTIR analysis confirmed that 3-APTES is successfully grafted on the surface of CuFe2O4 NPs. XRD results show the amorphous nature of blank CuFe2O4 NPs, and crystalline structure was observed for annealed and functionalized CuFe2O4 NPs. XRD results revealed that crystallite size ranges from 23.6 to 34.6 nm. SEM micrographs of blank CuFe2O4 NPs show the irregular shape and size of the nanostructure. The spherical and strongly linked structure was seen in the micrograph of functionalized CuFe2O4 NPs. EDX analysis revealed the nanostructure composed of Fe, Cu, O, and a small percentage of Si. The photocatalytic degradation efficiency of synthesized CuFe2O4 NPs was examined under UV irradiation in an aqueous medium against bromophenol blue (BPB) dye. The effect of different parameters such as irradiation time and pH on the photodegradation of BPB dye was studied by all three types of CuFe2O4 photocatalyst. Results show that the maximum photocatalytic degradation efficiency was observed for functionalized CuFe2O4 nanoparticles that degraded 98% of BPB dye in the acidic medium at pH = 1. The optimum contact time for dye degradation was 120 min by synthesized photocatalyst. Photodegradation performance of blank and annealed CuFe2O4 NPs is less than 90%. The synthesized CuFe2O4 NPs were recycled and reused, which shows good photocatalytic degradation efficiency up to 4 consecutive cycles. The kinetic model displayed that degradation reaction followed pseudo 1st order kinetics. The blank, annealed, and functionalized CuFe2O4 NPs have turnover numbers of 10.7x10 (Mudhoo et al., 2019), 12.9x10 (Mudhoo et al., 2019), and 22.2x10 (Mudhoo et al., 2019) (kg−1 sec−1) accordingly. In conclusion, all results revealed the high efficiency of prepared photocatalyst for tested hazardous dye from wastewater and encouraged more work on photodegradation of organic pollutants from wastewater.

Degradation of tetracycline using persulfate activated by a honeycomb structured S-doped g-C3N4/biochar under visible light

In this work, a novel S-doped g-C3N4/biochar (SCNBC) nanocomposite was fabricated to activate persulfate (PS) under visible light for tetracycline (TC) abatement. The maximum photocatalytic degradation efficiency of TC by the SCNBC/PS system exhibited 2.34 and 2.32 times of individual biochar (BC) and g-C3N4, respectively. This was mainly because the honeycomb tubular structure facilitated electrons transfer along the linear direction, favoring electron-hole (e−-h+) pair separation. Meanwhile, BC could serve as an electron reservoir to further inhibit e−-h+ recombination. Radical scavenging tests and electron paramagnetic resonance measurement revealed that h+ and O2− were the dominant oxidizing radicals in TC removal. Three possible degradation pathways of TC were proposed, the mechanism of which mainly included dealkylation, deamidation, dehydration, hydroxylation and ring-cleavage reactions. Overall, this work provides a facile photocatalyst to activate PS for removal of organic pollutants.