Visible Light Irradiation Time Research Articles

Visible light degradation of antibiotics catalyzed by nanoporous carbon/V2O5 nanocomposite: structural, optical and electrochemical properties

In this study, nanoporous carbon (NPC) decorated V2O5 (NPC/V2O5) nanocomposite synthesized by a hydrothermal technique using biomass-derived NPC nanoflakes towards the application of berberine hydrochloride (BH) dye degradation under visible light irradiation. The prepared samples were characterized by X-ray Diffraction (XRD), Raman spectroscopy, Field Emission Scanning Electron Microscopy (FE-SEM), Transmission Electron Microscopy (TEM), Energy-Dispersive X-ray (EDX), UV–Visible and Photoluminescence (PL) spectroscopy. Charge transfer resistance was measured by electrochemical impedance spectroscopy (EIS) and liner sweep voltammetry (LSV). XRD studies confirm the orthorhombic crystal structure of NPC/V2O5 nanocomposite. FE-SEM and TEM analysis validate their particle-like and sheet-like morphology of V2O5 and NPC respectively. Further, UV–visible DRS and PL spectra of the green synthesized NPC/V2O5 nanocomposite exhibited a low band-gap and reduced recombination rate compared to the pure counterpart which is better light-absorbing ability in the visible light region. Batch experiments represent the incorporation of NPC and V2O5 would lead to an increase the photocatalytic performance of NPC/V2O5 toward BH dye degradation. During the photocatalytic reaction, the NPC/V2O5 nanocomposite degraded rate around 97.7 % against BH dye within 80 min while pure V2O5 degraded 92.5 % of BH dye under same visible light irradiation time. Finally, the cyclic stability experiment exhibits the photocatalyst even stable after five consecutive tests.

Fe3O4/ZnO/L-lysine functionalized graphene oxide a promising nanocomposite with double Z-scheme visible photocatalytic and dark catalytic activity for water remediation

Developing multifunctional catalysts for efficient pollutant degradation in dark and visible light conditions represents a significant advancement in water remediation technology. This study reports the synthesis of a novel Fe3O4/ZnO/Lys-rGO nanocomposite via environmentally friendly methods that exhibit catalytic-photocatalytic activity for efficient degradation of organic pollutants. The synergistic effect of compositing Lys-rGO, a bio-organic component with a narrow band gap (1.08 eV), into the Fe3O4/ZnO inorganic composite induces a double Z-scheme mechanism by providing two pathways for effective charge separation in the visible photocatalytic activity of the nanocomposite. Additionally, the stored electrons in the very conductive Lys-rGO layers offer active sites for the catalytic activity of the nanocomposite in the dark. Meanwhile, ZnO generates reactive oxygen species (ROS) through surface oxygen vacancies, further contributing to the nanocomposite’s dark catalytic activity. The degradation of various organic pollutants (Methylene Blue, Tetracycline, Ciprofloxacin, Rhodamine B, and their mixture), as well as Congo Red, with low catalyst dosage and visible light irradiation time, demonstrates the high performance and versatility of this nanocomposite. This research highlights the potential of Lys-rGO in compositing with semiconductors to design multifunctional catalysts for cost-effective sustainable water purification technologies.

High efficient COVID-19 waste co-pyrolysis char/TiO2 nanocomposite for photocatalytic reduction of Cr(VI) under visible light.

Titanium dioxide (Titania) nanoparticle-coated biochar derived through co-pyrolysis of COVID-19 waste face mask (WFM) and Moringa oleifera seed cake (MO) provides an effective way to alleviate toxic metal in wastewater. This study investigates the effects of Biochar/titania photocatalyst preparation, characterization, and its photoreduction of Cr(VI). The morphological and functional modifications in the catalyst were identified using X-Ray diffraction, scanning electron microscopy, Fourier transform infrared spectroscopy, ultraviolet spectrophotometer, surface area analysis, and Raman spectrophotometer, respectively. The influencing parameters, namely, pH, photocatalyst dosage, initial pollutant concentration, and visible light irradiation time, have been investigated. The findings reveal that the Cr(VI) reduction by the photocatalyst was highly facilitated by photocatalytic process. The prepared photocatalyst shows higher and faster reduction rate of Cr(VI) and also improves the catalyst stability. The photoreduction of Cr(VI) ensembles well with pseudo-first order kinetics. At 180 min of reaction time, maximum Cr(VI) reduction of 98.65% was achieved at pH 2, 0.3 g/L catalyst dosage, and 10 ppm initial concentration, respectively. The synthesized photocatalyst shows excellent recycling performance up to 7 times, and these studies proved that the prepared catalyst is cost-effective and efficiently employed for removing pollutants.

The Morphological Evolution of Self-Assembled Silver Nanoparticles under Photoirradiation and Their SERS Performance

In this study, we conducted a one-step photochemical synthesis to produce silver nanoparticles (AgNPs) with irregular morphology. The synthesis process involved the photoconversion of Ag nanoseeds into self-assembled Ag nanostructures of various morphologies using a high-pressure sodium lamp with a wavelength of 589 nm, corresponding to an energy of 2.1 eV. During the synthesis, the color of the colloidal Ag nanoseeds gradually changed as the irradiation time increased, transitioning from yellow to brown, juniper green, basil green, ocean green, aegean blue, and finally to true blue. We characterized the morphological evolution of the resulting AgNPs, as well as their optical properties and aggregation behavior, using transmission electron microscopy, UV-vis spectroscopy, and dynamic light scattering. Furthermore, we evaluated the impact of the self-assembled morphology of the AgNPs on their surface-enhanced Raman scattering efficiency, using R6G as the target analyte. The results revealed that the colloidal AgNPs synthesized under a visible light irradiation time of 1 h consisted of circular nanoplates, hexagonal nanoplates, trapezoid nanoplates, and triangular nanoplates. These colloidal AgNPs exhibited excellent SERS activity when used as an SERS-active substrate in the form of an aqueous solution, enabling the detection of low concentrations of R6G down to 10−12 M.

Visible light photocrosslinking of sugar beet pectin for 3D bioprinting applications

Herein, we report the hydrogelation of sugar beet pectin (SBP) via visible light-mediated photocrosslinking and its applications in extrusion-based 3D bioprinting. Rapid hydrogelation (<15 s) was achieved by applying 405 nm visible light to an SBP solution in the presence of tris(bipyridine)ruthenium(II) chloride hexahydrate ([Ru(bpy)3]2+) and sodium persulfate (SPS). The mechanical properties of the hydrogel could be tuned by controlling the visible light irradiation time and concentrations of SBP, [Ru(bpy)3]2+, and SPS. High-fidelity 3D hydrogel constructs were fabricated by extruding inks containing 3.0 wt% SBP, 1.0 mM [Ru(bpy)3]2+, and 1.0 mM SPS. Human hepatoblastoma (HepG2) cells encapsulated in SBP hydrogels remained viable and metabolically active after 14 d of culture. Overall, this study demonstrates the feasibility of applying SBP and a visible light-mediated photocrosslinking system to the 3D bioprinting of cell-laden constructs for tissue engineering applications.

Construction of high-proportion dual bismuth-based Z-scheme Bi3O4Cl/Bi2MoO6 photocatalytic system via in-situ growth of Bi2MoO6 on Bi3O4Cl for enhanced photocatalytic degradation of organic pollutants

In this study, a high-proportion dual bismuth-based Z-scheme Bi3O4Cl/Bi2MoO6 photocatalytic system was constructed via the in-situ growth of Bi2MoO6 on Bi3O4Cl for enhanced visible-light driven photocatalytic degradation of organic pollutants in wastewater. The effects of the particle ratio of Bi3O4Cl and Bi2MoO6, organic pollutant initial concentration, catalyst dosage, visible-light irradiation time, degradation kinetics and reused times on the photocatalytic activity of the Z-scheme Bi3O4Cl/Bi2MoO6 photocatalyst were investigated. Moreover, the study compares the photocatalytic degradation extents of norfloxacin, tetracycline, crystal violet, acridine orange and methylene blue using the Z-scheme Bi3O4Cl/Bi2MoO6 photocatalyst, and proposes a possible mechanism on the Z-scheme Bi3O4Cl/Bi2MoO6 photocatalytic system. The results indicate that the high-proportion dual bismuth-based Z-scheme Bi3O4Cl/Bi2MoO6 photocatalyst performs superior photocatalytic activity at a 1.0:1.0 particle ratio. The fuzzy contact interfaces can be formed between Bi2MoO6 and Bi3O4Cl nanoparticles due to the direct in-situ growth of Bi2MoO6 on Bi3O4Cl, which can provide channels for the photo-generated electron transfer to construct the Z-scheme Bi3O4Cl/Bi2MoO6 photocatalytic system. After five cycles, the Z-scheme Bi3O4Cl/Bi2MoO6 photocatalyst maintains high photocatalytic performance. During the photocatalytic degradation, the photo-generated holes play dominant roles, while the contributions of superoxide radical and hydroxyl radical remain approximate. Thus, this photocatalytic technology displays promising application prospects for handling organic contaminants, including antibiotics and dyes, in wastewater.

Highly effective Fe-doped TiO2 nanoparticles for removal of toxic organic dyes under visible light illumination

This article addresses the synthesis of Fe3+ doped TiO2 nanoparticles with variations of molar concentrations of Fe3+ and their adequate use as potential photocatalysts for Photocatalysis applications. Synthesized photocatalysts were characterized thoroughly by different analytical techniques in terms of morphological, chemical, structural, crystalline, optical, electronic structure, surface area etc properties. The occurrence of red shift phenomenon of the energy band gap attributes to the transfer of charges and transition between the d electrons of dopant and conduction band (CB) or valence band (VB) of TiO2. The doping of Fe3+ ions generates more trap sites for charge carriers with the surface trap sites. Thorough experimental conclusions revealed that the Fe3+ ions necessarily regulate the catalytic property of TiO2 nanomaterial. The obtained total degradation efficiency rate of Methylene Blue (MB) was 93.3% in the presence of 0.1 M Fe3+ in the host material and for Malachite Green Oxalate the efficiency was 100% in the presence of 0.05 M and 0.1 M Fe3+in the host material. In both the cases the total visible light irradiation time was 90 min. The adsorption properties of the photocatalysts have been also performed in a dark for 90 min in the presence of MB dye. However, till now there are hardly reported photocatalysts which shows complete degradation of these toxic organic dyes by visible light driven photocatalysis. of potential values of valence and conduction band shows the production of active oxidizing species for hydrogen yield and the possible mechanism of the Schottky barrier has been proposed. A schematic diagram of visible light driven Photocatalysis has been pictured showing degradation activity of Fe3+-TiO2 catalysts sample.

Highly efficient LaFeO3/Bi2WO6 Z-scheme nanocomposite for photodegradation of tetracycline under visible light irradiation: Statistical modeling and optimization of process by CCD-RSM

The major problems of the semiconductor nanomaterials in the photocatalytic applications for degradation of organic contaminants are fast recombination of photogenerated electron-hole pairs and low visible light harvesting. Therefore, we tried to resolve these drawbacks by coupling LaFeO3 nanoparticles with Bi2WO6 nanoflakes and constructing of binary Z-scheme heterojunction through the facile solvothermal synthesis approach. The photocatalytic activity of the LaFeO3/Bi2WO6 heterojunction was studied through degradation of tetracycline (TC) upon visible light irradiation. The effects of experimental parameters, including LaFeO3/Bi2WO6 dosage, initial concentration of TC, visible light irradiation time, and solution pH on the photocatalyst performance of binary nanocomposite were analyzed by response surface methodology. The results of analysis of variance confirmed that these parameters have a significant effect on the TC degradation efficiency. The value of the first-order kinetic rate constant for removal of TC using LaFeO3/Bi2WO6 was calculated 0.1291 min−1, which was 20 and 10 times higher than pure LaFeO3 and Bi2WO6, respectively. Besides, LaFeO3/Bi2WO6 was shown the excellent photocatalytic stability after 4 cycles. Furthermore, the photocatalytic pathway for photodegradation of TC by binary LaFeO3/Bi2WO6 nanocomposite was proposed according to the trapping experiments of active species and the results were signify that the h+ and .OH are the predominant reactive species for the photodegradation of TC. Overall, we believe that current novel research opens a promising route for the preparation of highly efficient LaFeO3/Bi2WO6 photocatalyst and its usage for wastewater treatment.

Plasmonic resonance and type-I heterojunction interface in SrTiO3/CZTS/Ag nanocomposite for enhanced photocatalytic degradation of organic pollutants

As a novel plasmonic-heterostructure photocatalyst, the Silver (Ag)-modified SrTiO3/Cu2ZnSnS4 ternary nanocomposite was prepared through a co-precipitation method. The incorporation of Cu2ZnSnS4 (CZTS) and Ag into the SrTiO3 host phase reduced the mean particle size from 65 to 38 nm, doubled the surface area, and decreased the bandgap energy from 3.20 to 2.86 eV. A study of UV–visible diffuse reflectance spectroscopy (DRS) and valence band X-ray photoelectron spectroscopy (VB-XPS) confirmed the formation of type-I heterostructure charge transfer mechanisms between SrTiO3 and CZTS phases. Results from photoluminescence (PL), electrochemical impedance spectroscopy (EIS), and transient photocurrent experiments indicated that the ternary nanocomposite exhibits less internal resistance and a higher capacity for charge carrier separation. The effect of different photocatalytic experiment parameters on the photodegradation performance has been studied. In this regard, 90 min visible light irradiation time, 5 mg/L initial dye concentration, and 1 g/L powder dosage were found to be the best values. The designed system exhibited excellent photocatalytic performance, in which more than 99% of methylene blue (MB) dye degraded under optimum conditions. The reaction mechanism and kinetics were comparatively investigated in-depth. After a four-run cyclic experiment, the prepared photocatalyst exhibited high stability and reusability. The prepared sample demonstrated photocatalytic efficiencies of 87%, 66%, and 71% for the degradation of methyl orange (MO), Rhodamine-B (RhB), and Ciprofloxacin (CIP) pollutants, respectively.

One-Pot Facile Synthesis of CuO-CdWO4 Nanocomposite for Photocatalytic Hydrogen Production.

Hydrogen (H2) is a well-known renewable energy source that produces water upon its burning, leaving no harmful emissions. Nanotechnology is utilized to increase hydrogen production using sacrificial reagents. It is an interesting task to develop photocatalysts that are effective, reliable, and affordable for producing H2 from methanol and acetic acid. In the present study, CuO, CdWO4, and CuO-CdWO4 nanocomposite heterostructures were prepared using a cost-efficient, enviro-friendly, and facile green chemistry-based approach. The prepared CuO, CdWO4, and CuO-CdWO4 nanocomposites were characterized using X-ray diffraction pattern, Fourier-transform infrared spectroscopy, diffuse reflectance ultraviolet-visible spectroscopy, scanning electron microscopy, transmission electron microscopy, selected area electron diffraction (SAED) pattern, N2 physisorption, photoluminescence, and X-ray photoelectron spectroscopy techniques. The synthesized photocatalysts were utilized for photocatalytic H2 production using aqueous methanol and acetic acid as the sacrificial reagents under visible light irradiation. The influence of different variables, including visible light irradiation time, catalyst dosage, concentration of sacrificial reagents, and reusability of catalysts, was studied. The maximum H2 was observed while using methanol as a sacrificial agent over CuO-CdWO4 nanocomposite. This enhancement was due to the faster charge separation, higher visible light absorption, and synergistic effect between the CuO-CdWO4 nanocomposite and methanol.

Degradation of oxytetracycline hydrochloride using photocatalysis in the presence of Fe3O4/rGO/Co-doped ZnO/g-C3N4 nanocomposite particles: Experiment, modeling, optimization and mechanistic evaluation

In recent years, semiconductor materials have shown excellent potential in the field of photocatalytic degradation of antibiotics. To prepare a photocatalyst with excellent performance, an Fe 3 O 4 /rGO/Co-doped ZnO/g-C 3 N 4 tetrameric hybrid photocatalyst was successfully prepared for the first time by means of chemical precipitation using graphene oxide as the precursor. The developed quaternary photocatalyst was used for the degradation of oxytetracycline hydrochloride (OTC), and its photocatalytic activity was investigated. The structure and morphology of the composites were characterized by XRD, SEM, HR-TEM, ESR, N 2 adsorption, PL spectroscopy and UV-Vis DRS. The effects of different parameters on the degradation process were studied by the response surface method and artificial intelligence. The results showed that Fe 3 O 4 /rGO/Co-doped ZnO/g-C 3 N 4 was successfully synthesized. Under optimal conditions, the degradation rate of OTC was approximately 82% (the Fe 3 O 4 /rGO/Co-doped ZnO/g-C 3 N 4 dose was 0.16 g, the pH was 7.0, the initial concentration of OTC was 30 mg/L, and the visible light irradiation time was 70 min). pH is the most influential variable for OTC removal. At the same time, the degradation rate of OTC remained above 50% after 5 times of recycling, indicating that Fe 3 O 4 /rGO/Co-doped ZnO/g-C 3 N 4 photocatalyst had good stability and recoverability. In addition, the results of ESR and radical trapping experiments showed that ·O 2 - and ·OH were the main active species in the OTC removal process. • The prepared tetrameric hybrid photocatalyst effectively degrades oxytetracycline hydrochloride. • Fe 3 O 4 /rGO/Co-doped ZnO/g-C 3 N 4 nanomaterials are rapidly separated after the degradation process. • Artificial intelligence is used to model and optimize the degradation process. • ∙OH and ∙O 2 - are the main oxidizing species.

Facile preparation and modification of SrTiO3 through Ni–Cd co-doping as an efficient visible-light-driven photocatalyst

Visible light-driven Ni–Cd co-doped SrTiO3 photocatalyst was prepared through a co-precipitation technique. The influence of various amounts of doped elements on the properties of the pure SrTiO3 phase has been explored. The characterization was performed employing the X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), Raman, X-ray photoelectron spectroscopy (XPS), field emission-scanning electron microscopy (FESEM), UV–visible diffuse reflectance spectroscopy (DRS), photoluminescence (PL), electrochemical impedance spectroscopy (EIS), and transient photocurrent experiments. By Ni–Cd co-doping, the average particle size was reduced from 100 to 65 nm, the band gap value was lowered from 3.2 to 2.78 eV, and the powder's surface area was increased by about 2.3 times compared with the pure phase. Low PL peak intensity, small EIS radius, and higher photocurrent density of the 5 wt% doped sample indicate higher charge transfer efficiency than the pure sample. The effect of different photocatalytic experiment parameters on the photodegradation performance has been studied. In this regard, a 60-min visible light irradiation time, 1 g mL−1 initial dye concentration, and 0.7 g L−1 powder dosage were found to be the best values. After 60 min of visible light irradiation, doped SrTiO3 with 5 wt% Ni–Cd thoroughly degraded methylene blue (MB) dye. Additionally, the superoxide radical and holes also play a significant role in photodegradation as determined by the scavenger trapping test. Compared with MB, the prepared sample demonstrated less degradation ability for methyl orange (MO) and Rhodamine-B (RhB) dyes.

Photocatalytic degradation of tetracycline hydrochloride by a Fe3O4/g-C3N4/rGO magnetic nanocomposite mechanism: modeling and optimization.

The photocatalytic degradation of antibiotics requires a good separation efficiency of photogenerated electron-hole pairs and a wide visible light absorption range. Current studies have discussed the successful preparation of ferroferric oxide/graphite carbon nitride/reduced graphene oxide (Fe3O4/g-C3N4/rGO). The phase structure and morphology of the Fe3O4/g-C3N4/rGO composites were characterized by XRD, HR-TEM, SEM, and EDS. The obtained composites were used to degrade tetracycline hydrochloride (TCH) to evaluate its photocatalytic activity. The effects of four variables on the degradation of TCH were analyzed by the response surface method and artificial intelligence (gradient regression tree, random forest, artificial neural network, etc.). The results showed that the graphite carbon nitride in the catalyst maintained its original structure and that the photocatalytic activity was significantly improved. The degradation rate of TCH was 86.7% under the optimal conditions (the Fe3O4/g-C3N4/rGO dosage was 0.1g, pH = 7.0, the initial concentration of TCH was 20mg/L, and the visible light irradiation time was 60min). At the same time, the degradation rate of TCH changed little after the material was used five times, which indicates that the stability and recyclability of the Fe3O4/g-C3N4/rGO photocatalyst were excellent. Finally, a possible photocatalytic mechanism of the Fe3O4/g-C3N4/rGO photocatalyst is proposed in this paper.

Zeolitic imidazolate framework grafted by cobalt tungstate as an efficient photocatalyst for photocatalytic oxidative desulfurization of dibenzothiophene

In this research, novel nanohybrid of zeolitic imidazolate framework supported cobalt tungstate semiconductor (ZIF-67@CoWO4) with various CoWO4 loading ratios (from 0 to 30 %wt) has been fabricated as a visible-light-driven photocatalyst for dibenzothiophene (DBT) removal from model fuel. XRD, UV-DRS, FE-SEM, EDX, BET and VSM characterizations were used to analyze the fabricated nanocomposites. At specific experimental conditions (100 mg/l DBT in model fuel, photocatalyst dosage of 2 g/l, visible light irradiation time of 2 h and H2O2/DBT mole ratio of 8:1), the ZIF-67@(1 wt%)CoWO4 sample exhibited excellent photocatalytic oxidative desulfurization (PODS) activity (96.7%) between different prepared photocatalysts, The improved reaction performance of ZIF-67@(1%wt)CoWO4 heterostructure can be attributed to the reciprocal effects of the high adsorption capacity of ZIF-67, optical properties of CoWO4 nanoparticles and the high charges separation and transfer efficiencies. Besides, the ZIF-67@CoWO4 photocatalyst possesses good stability for PODS and can be reused for five reaction cycles without a significant activity loss, indicating that it might be very useful in the deep PODS of hydrocarbon fuel.

Synthesis, Performance Measurement of Bi2SmSbO7/ZnBiYO4 Heterojunction Photocatalyst and Photocatalytic Degradation of Direct Orange within Dye Wastewater under Visible Light Irradiation.

Originally, the new catalyst Bi2SmSbO7 was synthesized by the hydrothermal synthesis method or by the solid-phase sintering method at a lofty temperature. A solvothermal method was utilized to prepare a Bi2SmSbO7/ZnBiYO4 heterojunction photocatalyst (BZHP). The crystal structure of Bi2SmSbO7 belonged to the pyrochlore structure and face-centered cubic crystal system by the space group of Fd3m. The cell parameter a was equivalent to 10.835(1) Å (Bi2SmSbO7). With Bi2SmSbO7/ZnBiYO4 heterojunction (BZH) as the photocatalyst, the removal rate (RR) of direct orange (DO) and the total organic carbon were 99.10% and 96.21% after visible light irradiation of 160 min (VLI-160M). The kinetic constant k toward DO concentration and visible light irradiation time (VLI) with BZH as photocatalyst reached 2.167 min−1. The kinetic constant k, which was concerned with total organic carbon, reached 0.047 min−1. The kinetic curve that came from DO degradation with BZH as a catalyst under VLI conformed to the second-order reaction kinetics. After VLI-160M, the photocatalytic degradation (PD) removal percentage of DO with BZH as the photocatalyst was 1.200 times, 1.268 times or 3.019 times that with Bi2SmSbO7 as the photocatalyst, ZnBiYO4 as the photocatalyst or with nitrogen-doped titanium dioxide as the photocatalyst. The photocatalytic activity (PA) was as following: BZH > Bi2SmSbO7 > ZnBiYO4 > nitrogen-doped titanium dioxide. After VLI-160M for three cycles of experiments with BZH as the photocatalyst, the RR of DO reached 98.03%, 96.73% and 95.43%, respectively, which meant that BZHP possessed high stability. By using the experiment of adding a trapping agent, the oxidative purifying capability for degradation of direct orange, which was in gradual depressed order, was as following: hydroxyl radical > superoxide anion > holes. Finally, the possible degradation pathway and degradation mechanism of DO were discussed systematically. A new high active heterojunction catalyst BZHP, which could efficiently remove toxic organic pollutants such as DO from dye wastewater after VLI, was obtained. Our research was meant to improve the photocatalytic property of the single photocatalyst.

Preparation, Property Characterization of Gd2YSbO7/ZnBiNbO5 Heterojunction Photocatalyst for Photocatalytic Degradation of Benzotriazole under Visible Light Irradiation

The Gd2YSbO7/ZnBiNbO5 heterojunction photocatalyst was synthesized for the first time by the facile in situ precipitation method. The structural properties of a Gd2YSbO7/ZnBiNbO5 heterojunction photocatalyst were characterized by X-ray diffractometer, scanning electron microscope-X ray energy dispersive spectra, X-ray photoelectron spectrograph and UV-Vis diffuse reflectance spectrophotometer. The band gap energy (BGE) of Gd2YSbO7 or ZnBiNbO5 was found to be 2.396 eV or 2.696 eV, respectively. The photocatalytic property of Gd2YSbO7 or ZnBiNbO5 or Gd2YSbO7/ZnBiNbO5 heterojunction photocatalyst (GZHP) was reported. After a visible-light irradiation of 145 minutes (VLI-145 min), the removal rate (RER) of benzotriazole reached 99.05%, 82.45%, 78.23% or 47.30% with Gd2YSbO7/ZnBiNbO5 heterojunction (GZH), Gd2YSbO7, ZnBiNbO5 or N-doped TiO2 (NTO) as photocatalyst. In addition, the kinetic constant k, derived from the dynamic curve toward benzotriazole concentration and visible light irradiation time with GZH as a photocatalyst, reached 0.0213 min−1. Compared with Gd2YSbO7 or ZnBiNbO5 or NTO, GZHP showed maximal photocatalytic activity (PHA) for the photocatalytic degradation of benzotriazole under visible-light irradiation. The RER of total organic carbon during the photocatalytic degradation of benzotriazole reached 90.18%, 74.35%, 70.73% or 42.15% with GZH as a photocatalyst or with Gd2YSbO7, ZnBiNbO5 or NTO as a photocatalyst after VLI-145 min. Moreover, the kinetic constant k, which came from the dynamic curve toward total organic carbon concentration and visible light irradiation time with GZH as a photocatalyst, reached 0.0110 min−1. Based on above results, GZHP showed the maximal mineralization percentage ratio when GZHP degraded benzotriazole. The results showed that hydroxyl radicals was the main oxidation radical during the degradation of benzotriazole. The photocatalytic degradation of benzotriazole with GZH as a photocatalyst conformed to the first-order reaction kinetics. Our research aimed to improve the photocatalytic properties of the single photocatalyst.

Improvement in photocatalytic activity of titanium dioxide nanoparticles through doping and calcination for textile wastewater treatment under visible light

The photocatalytic degradation of commercial textile azo dye, namely C.I Acid red 2 also called as methyl red has been studied. TiO2 nanoparticles doped with zinc nitrate were made by sol–gel technique and calcined at higher temperature that leads to the formation of mixed phases and improved photocatalytic action of nanoparticles underneath visible light. The obtained nanoparticles are characterized by SEM, XRD and FTIR techniques along with zeta potential measurement. The nanoparticles were found to be crystalline with a size of around 58 nm to 192 nm. The effect of visible light irradiation time on photodegradation was investigated. Optimum pH for degradation of the dye solution was determined. The reusability of the photocatalyst was analyzed by recycling experiments. The degradation of the chosen dye was monitored using UV–Vis spectroscopy. Maximum degradation of 85 % was obtained for a time duration of 180 min. From kinetics studies it was noticed that degradation of methyl red followed pseudo second order kinetics. The results suggest that using a suitable photocatalyst and choosing the right operational settings can readily result in complete decolorization of azo dye solutions.

Formulating Multiphase Medium Anti-wetting States in an Air-Water-Oil System: Engineering Defects for Interface Chemical Evolutions.

Studies which regulate macroscopic wetting states on determined surfaces in multiphase media are of far-reaching significance but are still in the preliminary stage. Herein, inspired by the wettability subassembly of fish scales, Namib desert beetle shell, and lotus leaf upper side, interfaces in the air-water-oil system are programmed by defect engineering to tailor the anti-wetting evolution from double to triple liquid repellency states. By controlling the visible light irradiation and plasma treatment, surface oxygen vacancies on CuxO@TiO2 nanowires (NWs) can be healed or reconstructed. The original membrane or the membrane after plasma treatment possesses abundant surface oxygen vacancies, and the homogeneous hydrophilic membrane shows only double anti-wetting states in the water-oil system. By the unsaturated visible light irradiation time, the surface oxygen vacancy partially healed, the heterogeneous hydrophilic-hydrophobic components occupied the membrane surface, and the anti-wetting state finally changed from double to triple in the air-water-oil system. After the illumination time reaches saturation, it promotes the healing of all surface oxygen vacancies, and the membrane surface only contains uniform hydrophobic components and only maintains double anti-wetting state in the air-oil system. The mechanism of the triple anti-wetting state on a heterogeneous surface is expounded by establishing a wetting model. The wetting state and the adhesion state of the CuxO@TiO2 NW membrane show regional specificity by controlling the illumination time and region. The underwater oil droplets exhibit the "non-adhesive" and "adhesive" state in a region with unsaturated irradiation time or in an unirradiated region, respectively. Underwater oil droplet manipulation can be accomplished easily based on switchable wettability and adhesion. Current studies reveal that defect engineering can be extended to anti-wetting evolution in the air-water-oil system. Constructing an anti-wetting interface by heterogeneous components provides reference for designing the novel anti-wetting interface.

Influence of Aloe vera and PEG on the evaluation of photocatalytic degradation of MG dye under UV light and visible light irradiation of ZnO nanomaterials

Photocatalytic degradation is an effective method to prevent the environmental pollution caused by organic pollutants. The effect of different combinations on the properties of zinc oxide was studied by preparing polyethylene glycol (PEG) capped ZnO, Aloe vera mediated ZnO, and PEG/Aloe vera combined ZnO via the sol-gel synthesis method. The size and structure of the synthesized samples were confirmed by XRD and SEM analysis. The decrease in bandgap energy value of ZnO/Aloe/PEG than ZnO/Aloe, and ZnO/PEG indicates the easy excitation of electrons in the latter. Here, the photocatalytic degradation of three different ZnO combinations was tested against Malachite Green (MG) dye with twenty minutes of UV light and visible light irradiation time. Furthermore, the photocatalytic degradation efficiency of textile dye wastewater was also evaluated by ZnO/Aloe/PEG combination under both UV light and visible light irradiation. These findings proved the overwhelming photocatalytic degradation of plant extract and surfactant based ZnO, which has been used as effective remediation to treat textile dye effluent.

Construction of graphene based photocatalysts for photocatalytic degradation of organic pollutant and modeling using artificial intelligence techniques

In this study, graphene based photocatalysts containing different silver doped titanium dioxide nanosheets (Ag-TNs-RGO) were fabricated. The successful reduction of graphene oxide (as support) was confirmed by Raman analysis. Also, powder X-ray diffraction (PXRD) analysis confirmed pure anatase phase of the obtained TiO2 nanosheets as well as Raman spectroscopy. The efficiency of Ag-TNs-RGO (0.038) for degradation of tetracycline (TC) antibiotic as an organic pollutant model under visible light and UV irradiation for 180 min was evaluated 48.57% and 77.84%, respectively. Artificial neural network (ANN) and adaptive neuro-fuzzy inference system (ANFIS) were used to describe the photocatalytic degradation process. Five degradation variables (catalyst dosage, initial concentration of TC, silver nitrate content, visible light irradiation time and ammonium persulfate (APS) concentration) were defined as the input variables of the models and the removal percentage of TC was the output. Sensitivity analysis was performed by weights method on the outputs of models.