Natural Sunlight Irradiation Research Articles

Nanoarchitectonics of zirconium modified ZnTiO3 for photo and electro-catalysts in dye degradation and water splitting applications

Perovskite oxides are attractive in the catalytic application owing to their stability, tuning characteristics, and easy synthesis process. Here, ZnTi1-xZrxO3 (x = 0.5) (abbreviated as ZZT0.5) is synthesized under the chemical precursor solution decomposition method and calcined at 700 °C for 3 h. The cubic phase nanosized material exhibits cubic shape morphology with the proper ratio of the existing elements as from observed structural and morphological characterizations. In the photocatalytic dye degradation under natural sunlight irradiation, the materials show >90% color degradation of congo red and murexide. The observed result in the presence of solar light irradiation highlights an elevated photocatalytic efficiency. The pseudo-first-order degradation process shows a high correlation coefficient with good stability of the material in the reusable study. This ZnTiO3-based perovskite material has not been used previously in electrocatalytic water splitting. During oxygen evolution reaction (OER), and hydrogen evolution reaction (HER) conditions, the material deposited on NF substrate showed 335 mV and 165 mV overpotential at 10 mA cm−2 current density, respectively which is indicative of notable electrocatalytic water splitting activity of the perovskite material designed herein. The long-term chronoamperometry (CA) study confirms the material's stability during both HER and OER conditions with negligible loss in activity over a period of 12 h. The post-catalytic characterizations confirm the robust nature of the material possessing the same phase characteristics. As an earth-abundant, low-cost material, the material designed herein shows the significant activity of environmental sustainability in terms of water treatment as well as green hydrogen production via electrolysis.

Insights into the mechanisms of natural organic matter on the photodegradation of indomethacin under natural sunlight and simulated light irradiation

Indomethacin (INDO) is an antipyretic and analgesic pharmaceutical that has been widely detected in the aquatic environment. Photodegradation is an essential pathway for removal of INDO in sunlit surface water, however the effect of dissolved organic matter (DOM) on its photodegradation and the ecotoxicity of photodegradation products are largely unknown. In this study, the effect of DOM on the photodegradation of INDO under both natural and simulated light irradiation was studied. The results showed that indirect photolysis is the main photodegradation pathway of INDO in presence of DOM where 3DOM* plays the most important promoting role. Compared to commercial DOM (SRNOM and SRFA), DOM extracted from local-lake water (SLDOM) promoted the photodegradation to the highest extent. Although the steady-state concentrations of 3DOM* of SRNOM and SRFA were higher than SLDOM, their inhibition effect surpassed SLDOM namely higher light screening effect and phenolic antioxidant concentrations. The photodegradation pathway in pure water is different from that in DOM system where the decarboxylation of acetic acid chain and the oxidative fracture of indole ring are the main degradation pathways. Density Functional Theory (DFT) calculation further supports the proposed degradation pathways of INDO. ECOSAR calculation showed that the toxicity of INDO photodegradation products to aquatic organisms may maintain or even exceed its parent compound. Therefore, comprehensive understanding of the impact of DOM on the photodegradation of INDO is of crucial significance for evaluating its ecological risk in the natural environment.

Synthesis and Characterization of Poly(vanillin pyrrole)/Zinc Oxide Composite for Photocatalysis Application under Natural Sunlight Irradiation

Synthesis and Characterization of Poly(vanillin pyrrole)/Zinc Oxide Composite for Photocatalysis Application under Natural Sunlight Irradiation

Influence of Radical Scavenger on Radiation Synthesis of Graphene Oxide/TiO2 Nanotubes/Ag Nanoparticles Nanocomposites and Their Dye Photodegradation Efficiency

Aqueous solutions of graphene oxide (GO), TiO2 nanotubes (TNTs), and silver nanoparticles (AgNPs) were synthesized through a facile, single-step radiolytic method at room temperature and ambient pressure. The resulting material, referred to as GO-TNTs-AgNPs (GTA), was investigated for its potential application in the photodegradation of Rhodamine-B (RhB) dye. This synthesis process relies on the interaction of high-energy gamma rays from a 60Co source with the water in the aqueous solutions. The main objective of this study was to evaluate the effect of irradiation dose and the presence of polyethylene glycol (PEG) solution on the combination within the nanocomposite materials. The inefficiency of GTA synthesis experimentally was in agreement with the hydroxyl radical (HO•) scavenger. Then, the irradiated materials were structurally characterized using various spectroscopic methods (Fourier transform infrared (FTIR), X-ray diffraction (XRD), Raman spectroscopy, and ultraviolet-visible absorption (UV–Vis)). Scanning electron microscopy (SEM) studies reveal the variable morphology of nanocomposites. GTA samples in water exhibited significantly higher degradation efficiency on Rhodamine B dye under natural sunlight irradiation conditions.

Preparation of magnetic CuO/Fe3O4/ZnO photocatalyst for complete degradation of methylene blue under natural sunlight irradiation

A ternary CuO/Fe3O4/ZnO photocatalyst was successfully produced using a low-temperature hydrothermal method. Subsequently, the prepared photocatalyst was used to degrade Methylene Blue (MB) dye under natural sunlight irradiation. In this system, the catalyst gained magnetic properties by incorporating Fe3O4 in the ZnO nanostructure. However, the resulting photocatalytic performance was reduced, compared to the bare ZnO. To remedy this issue, a p-type CuO semiconductor was coupled to form a p-n junction between CuO and ZnO. The optimal content of CuO was 0.3 mole percent. The ternary CuO/Fe3O4/ZnO composite enhanced the removal efficiency (100%), while the mineralization was about 51.4% within 50 min under sunlight irradiation in a neutral medium. The as-prepared catalyst retained its efficiency to degrade MB dye and remained highly stable, even after six consecutive cycles. The degradation mechanism was investigated based on identifying the degradation products using liquid chromatography-mass spectrometry.

Sunlight-assisted photocatalytic degradation of tartrazine in the presence of Mg doped ZnS nanocatalysts

In this work, Mg2+ doped ZnS nanoparticles were prepared by solvothermal method, using ethanol as solvent at 135 °C.The nanoparticles were characterized by XRD, SEM, UV–vis and PL. After doping, XRD revealed a reduction in lattice parameter, confirming Mg2+ substitution into the ZnS host lattice. The UV–vis study indicated that the incorporation of Mg2+ ions does not modify the band gap width of the nanoparticles. The PL spectra measured at 325 nm excitation wavelength, reveals that the photogenerated electrons of Zn0·9Mg0·1S have a slower recombination rate than ZnS nanoparticles. The XPS finding confirm that the chemical environment of the elements has been affected by the presence of the Mg2+. The Valence Band Maximum (VBM) was determined to be 0.2eV for ZnS and 1eV for Zn0·9Mg0·1S, respectively. These findings confirm the perturbation of electronic properties when Mg2+ is added to the ZnS. The photocatalytic ability was estimated through the degradation of tartrazine under natural-sunlight irradiation. Zn0.9Mg0.1S shows a high photocatalytic activity, compared to ZnS nanoparticles. The photocatalytic degradation was studied through different parameters, such as: the source of irradiation, the pH, the dye concentration, the catalyst concentration, and the recyclability. The degradation investigation shows that tartrazine is better oxidized at free pH = 6,7, with a dye concentration of 20 mg/L and a catalyst dosage of 1 g/L. Zn0.9Mg0.1S degraded 98% of tartrazine under natural-sunlight irradiation. In addition, the catalyst retained a good photo-degradation capacity, even after many treatment cycles. The scavengers study confirmed that the main active species responsible for the photocatalytic degradation of tartrazine were the oxidation groups (O2•-).

Sunlight Induced Photocatalytic Degradation of Methylene Blue Dye by SnS2 Nanoplates Under Natural Sunlight Exposure

Removal of dyes from water bodies is a significant concern throughout the world. In this study, SnS2 nanoplates were synthesized by a hydrothermal synthetic route at 160°C, and it is effectively characterized by various techniques. The XRD peaks confirmed the hexagonal planes of SnS2. The nanoplates-like morphology was revealed by FESEM and HRTEM. The optical band gap was investigated by UV-vis DRS and showed a reflection edge with corresponding energy at 2.2 eV. The photocatalytic activity of the SnS2 nanoplates is tested against the degradation of methylene blue under natural sunlight irradiation. About 95% degradation of methylene blue is observed in 120 min with the photocatalytic degradation rate of 0.021min-1. Results confirmed that the SnS2nanoplatescould facilitate 95 % degradation of methylene dye and followed the first-order kinetic model.

Photocatalytic Degradation of Rhodamine B Dye by Bi2MoO6 Microspheres under Natural Sunlight Irradation

Removal of dyes from water bodies is a significant concern throughout the world. In this study, Bi2MoO6 microspheres were synthesized by a hydrothermal synthetic route at 180°C, and it is effectively characterized by various techniques. The XRD peaks confirmed the orthorhombic planes of Bi2MoO6. The microsphere-like morphology was revealed by FESEM and HRTEM. The optical band gap was investigated by UV-vis DRS and showed a reflection edge with corresponding energy at 2.68 eV. The photocatalytic activity of the Bi2MoO6 microsphere is tested against the degradation of rhodamine B under natural sunlight irradiation. About 90% degradation of rhodamine B is observed in 90 min with the photocatalytic degradation rate of 0.038min-1. Results confirmed that the Bi2MoO6microspherecould facilitate 90% degradation of RhB dye and followed the first-order kinetic model.

Fabrication of hierarchical flower-like WO3 nanoparticles for effective metal ions sensing and catalytic degradation of organic dyes

In this work, we report on the synthesis of flower-like tungsten oxide nanoparticles (WO3 NPs) using a simple precipitation method. This paper reports a simple method for synthesizing flower-like WO3 NPs, which can be used for environmentally treating hazardous organic pollutants. The photocatalytic degradation of model artificial Orange II and Congo red was assessed under natural sunlight irradiation. The surface morphologies, crystallinity, and binding energy of the synthesized WO3 NPs were determined. The synthesized WO3 NPs exhibited good photodegradation percentages of approximately Orange II (97.6%) and Congo red dye (98.2%) after 120 min of irradiation. Furthermore, the WO3 NPs maintained their degradation ability for up to three cycles. In addition, WO3 NPs were examined in different metal ions sensing (Hg2+, Fe2+, Cu2+, Ni2+, and Cd2+) in an aqueous solution. The results showed that the WO3 NPs exhibited excellent Cd2+ ion sensing. Based on the investigations, WO3 NPs proved to be an efficient photocatalyst and hold promise as the best material for future applications in preventing water pollution.

Size-dependent long-term weathering converting floating polypropylene macro- and microplastics into nanoplastics in coastal seawater environments

In this study, we systematically developed the long–term photoaging behavior of different-sized polypropylene (PP) floating plastic wastes in a coastal seawater environment. After 68 d of laboratory accelerated UV irradiation, the PP plastic particle size decreased by 99.3 ± 0.15%, and nanoplastics (average size: 435 ± 250 nm) were produced with a maximum yield of 57.9%, evidencing that natural sunlight irradiation–induced long-term photoaging ultimately converts floating plastic waste in marine environments into micro- and nanoplastics. Subsequently, when comparing the photoaging rate of different sized PP plastics in coastal seawater, we discovered that large sized PP plastics (1000–2000 and 5000–7000 μm) showed a lower photoaging rate than that of small sized PP plastic debris (0–150 and 300–500 μm), with the decrease rate of plastic crystallinity as follow: 0–150 μm (2.01 d−1) > 300–500 μm (1.25 d−1) > 1000–2000 μm (0.780 d−1) and 5000–7000 μm (0.900 d−1). This result can be attributed to the small size PP plastics producing more reactive oxygen species (ROS) species, with the formation capacity of hydroxyl radical •OH as follows: 0–150 μm (6.46 × 10−15 M) > 300–500 μm (4.87 × 10−15 M) > 500–1000 (3.61 × 10−15 M) and 5000–7000 μm (3.73 × 10−15 M). The findings obtained in this study offer a new perspective on the formation and ecological risks of PP nanoplastics in current coastal seawater environments.

Efficient degradation of cationic dyes by ZnO and ZnO–Fe(III) quantum dots under natural sunlight and UV light

Zinc oxide (ZnO) quantum dots (QDs) are very attractive to many applications due to their optical and electronic properties and low toxicity. Among the applications, ZnO has been applied to photocatalysis for degradation or organic pollutants. However, what is still not clear is the function of organic dyes that absorb in the visible region, when they are together with semiconductors known for their best photocatalytic performance in the UV region. Herein, the degradation efficiency of two cationic dyes under natural sunlight irradiation and UV light in the presence of ZnO and ZnO:Fe(III) QDs with the dopant at 0.02, 0.04, and 0.07 mol% was investigated. The QDs were prepared via sol-gel method in ethanol and the photocatalytic assays were carried out in the same environment. Fe(III)-doped ZnO QDs with 0.04 mol% gave the highest apparent rate constants with degradation percentage equal to 84.3% and 66.9%, for methylene blue (MB) and astrazon blue FGGL 300% (AB), respectively, after 7 min under sunlight irradiation. Experiments were carried out with scavengers for hydroxyl (⋅OH) and anion superoxide (O2−⋅) radicals, tert-butanol and 1,4-benzoquinone (1,4-BQ), respectively. MB degradation course did not change in the ethanolic medium, known as ⋅OH scavenger, as well as with an extra amount of tert-butanol. However, the photocatalytic efficiency strongly decreased under the presence of 1,4-BQ. Thus, it is assumed that the MB degradation route in ethanol occurs mainly through the radical species O2−⋅. The study proved to be very sustainable and eco-friendly, being carried out in an ethanolic environment and with natural sunlight. This strategy ensured maximum surface efficiency and photocatalytic activity.

Efficient photocatalytic tetracycline elimination over Z-scheme g-C3N4/Bi5O7I heterojunction under sunshine light: Performance, mechanism, DFT calculation and pathway

A series of Z-scheme heterojunction g-C3N4/Bi5O7I composites were fabricated via a facile electrostatic self-assembly procedure. The optimum 15%-g-C3N4/Bi5O7I displayed good degradation efficiency toward tetracycline (TC) under visible light irradiation. The improvement of photocatalytic efficiency was mainly attributed to the generation of photo-induced h+ and O2•− radical. The migration route of photo-induced h+ and e− between g-C3N4 and Bi5O7I was investigated by XPS analysis, EPR test, photocatalytic mechanism and DFT calculations. The degradation pathways and the toxicological simulation of TC were evaluated. It was revealed that the intermediates produced during degradation process exhibited lower toxicity than the pristine TC. In addition, 15%-g-C3N4/Bi5O7I exhibited good stability and reusability. Considering its potentials in practical application, 15%-g-C3N4/Bi5O7I displayed high photocatalytic efficiency under natural sunlight irradiation. In all, this work offered a deep insight into the photocatalytic mechanism of tetracycline degradation over bismuth-rich bismuth oxyhalide/g-C3N4 heterojunction photocatalysts.

Insight into the Charge-Ratio-Tuned Solar Vapor Generation of Polyion Complex Hydrogel/Coal Powder Composites.

Solar-driven water purification has been deemed a promising technology to address the issue of clean water scarcity. However, traditional solar distillers often suffer from low evaporation rates under natural sunlight irradiation, while the high costs of the fabrication of photothermal materials further hinders their practical applications. Here, through the harnessing of the complexation process of oppositely charged polyelectrolyte solutions, a polyion complex hydrogel/coal powder composite (HCC)-based highly efficient solar distiller is reported. In particular, the influence of the charge ratio of polyanion-to-polycation on the solar vapor generation performance of HCC has been systematically investigated. Together with a scanning electron microscope (SEM) and the Raman spectrum method, it is found that a deviation from the charge balance point not only alters the microporous structure of HCC and weakens its water transporting capabilities, but also leads to a decreased content of activated water molecules and enlarges the energy barrier of water evaporation. As a result, HCC prepared at the charge balance point exhibits the highest evaporation rate of 3.12 kg m-2 h-1 under one sun irradiation, with a solar-vapor conversion efficiency as high as 88.83%. HCC also exhibits remarkable solar vapor generation (SVG) performance for the purification of various water bodies. In simulated seawater (3.5 wt% NaCl solutions), the evaporation rate can be as high as 3.22 kg m-2 h-1. In acid and alkaline solutions, HCCs are capable of maintaining high evaporation rates of 2.98 and 2.85 kg m-2 h-1, respectively. It is anticipated that this study may provide insights for the design of low-cost next-generation solar evaporators, and broaden the practical applications of SVG for seawater desalination and industrial wastewater purification.

Photosensitive Dye as an Ideal Peroxymonosulfate Activator for Efficient Self-Degradation: A Novel Idea of Using Waste to Treat Waste.

Commonly used peroxydisulfate (PS) or peroxymonosulfate (PMS) activation methods have been limited in their practical application due to certain drawbacks, such as high cost, high energy consumption and secondary pollution. In this study, a catalyst-free alizarin green (AG) self-activating PMS catalytic system was constructed based on photosensitization properties of dye, which ultimately achieved efficient degradation of the dye activator, also the target pollutant. Here, 52.5% of the 100 mL mixture of 10 mg/L AG decomposed within 60 min with 1 mM PMS under visible-light irradiation, thereby showing a strong pH adaptation. Mechanism of AG self-activating PMS was revealed that the photo-excited AG can effectively transfer photo-induced electrons to PMS for its activation, which generates reactive oxidizing species dominated by singlet oxygen (1O2), and supplemented by hydroxyl radical (•OH), superoxide radical (O2•-) and sulfate radical (SO4•-) to realize the efficient self-degradation of the dye pollutants. Moreover, such self-catalytic system operated well under natural sunlight irradiation, indicating the great application potential in the actual wastewater treatment. Herein, photosensitive dye acted as an ideal PMS activator realizing its efficient self-degradation, which provides a novel idea of "using waste to treat waste" for developing wastewater treatment process in a high-efficiency and low-consumption way.

B–Sn/TiO2 nanoparticles for photodegradation of metronidazole antibiotics under different lights

A novel B and Sn co-doped TiO2 (B–Sn/TiO2) nanoparticle photocatalyst with different compositions was synthesized using the sol-gel method. The weight ratios of B and Sn in TiO2 were 1:9, 6:6, and 2:3, respectively. The resultant nanoparticles have completed a detailed characterization examination using XRD, FTIR, FESEM-EDS, TEM, UV–vis DRS, PL, BET, Zeta potential, and XPS. The photocatalytic activity of B–Sn/TiO2 nanoparticles was investigated for the degradation of aqueous metronidazole (MNZ) solution with UV-C and natural sunlight irradiation. Among the different compositions of the nanoparticles, B–Sn/TiO2 (1:9) exhibited better photocatalytic activity because of its high charge separation ability, confirmed by significant PL quenching. Under ideal conditions (MNZ concentration of 10 mg/L, pH 9, catalyst dosage of 20 mg), a maximum MNZ removal efficiency of ∼96% was obtained in UV-C irradiation within 120 min. However, under the same experimental conditions in natural sunlight, the removal efficiency of MNZ was ∼94% in just 60 min. The mineralization of MNZ up to ∼53% in 3 h under sunlight was studied from the decrease in TOC values. The scavenger test was used to estimate a plausible photocatalytic degradation mechanism of MNZ, and it was observed that the •O2− radical was potentially active in the degradation of MNZ. Cyclic experiments showed that B–Sn/TiO2 (1:9) was reusable for up to four cycles, confirming that it can be used as a cost-effective and environmentally friendly photocatalyst.

Magnetically recoverable sol-gel auto-combustion developed Ni1-xCuxDyyFe2-yO4 magnetic nanoparticles for photocatalytic, electrocatalytic, and antibacterial applications

Copper and dysprosium doped NiFe2O4 magnetic nanomaterials, Ni1-xCuxDyyFe2-yO4 (x = y = 0.00, 0.01, 0.02, 0.03), was prepared by utilizing sol-gel auto-combustion approach to inspect the photodegradation of methylene blue (MB) pollutant and also, to perform the electrocatalytic water splitting and antibacterial studies. The XRD analysis reveal the growth of a single-phase spinel cubic structure for produced nanomaterials. The magnetic traits show an increasing trend in saturation magnetization (Ms) from 40.71 to 47.90 emu/g along with a decreasing behaviour of coercivity from 158.09 to 156.34 Oe at lower and higher Cu and Dy doping content (x = 0.0–0.01). The study of optical band gap values of copper and dysprosium-doped nickel nanomaterials decreased from 1.71 to 1.52 eV. This will increase the photocatalytic degradation of methylene blue pollutant from 88.57% to 93.67% under natural sunlight, respectively. These findings clearly show that under natural sunlight irradiation for 60 min, the produced N4 photocatalyst displays the greatest photocatalytic activity with a maximum removal percentage of 93.67%. The electrocatalytic characteristics of produced magnetic nanomaterials for both HER and OER were examined with a Calomel electrode taking as a reference in a 0.5 N H2SO4 and 0.1 N KOH electrolyte. The N4 electrode demonstrated considerable 10 and 0.024 mA/cm2 of current density, with onset potentials of 0.99 and 1.5 V for HER and OER and also, have tafel slopes of 58.04 and 295 mV/dec, respectively. The antibacterial activity for produced magnetic nanomaterials was examined against various bacteria (Bacillus subtilis, Staphylococcus aureus, S. typhi, and P. aeruginosa) in which N3 sample produced significant inhibition zone against gram-positive bacteria (Bacillus subtilis and Staphylococcus aureus) but no zone of inhibition against gram-negative bacteria (S. typhi and P. aeruginosa). With all these superior traits, the produced magnetic nanomaterials are highly valuable for the wastewater remediation, hydrogen evolution, and biological applications.

Solar Light-Induced Photocatalytic Response of BiOCl/PANI Composite towards the Degradation of Tetracycline

Photocatalytic degradation has gained much attention as a means of reducing water contamination as, with increasing industrialization and population growth, water pollution is a menace to both individuals and the environment. In this respect, metal oxide photocatalysts demonstrate effectiveness due to their excellent properties, such as their narrow band gap and low recombination rate of charge carriers. Here, various weight ratios of BiOCl/PANI composites have been synthesized by the simple wet chemical method. The crystallinity, oxidation state and surface chemical composition of the elements were analyzed by XRD and XPS techniques. FESEM and HRTEM images verified the formation of BiOCl nanosheets, covered well with PANI nanofibers, while EDX spectra revealed the uniform distribution of elements. The high surface area of the photocatalyst with a mesoporous nature was revealed by BET analysis. Low recombination rate and narrow band gap, suitable for photocatalysis, were confirmed by PL and UV–DRS spectroscopy. The photocatalytic performance of the photocatalyst was tested for the photodegradation of rhodamine-B (Rh-B) and tetracycline (TC) under natural sunlight irradiation. Kinetic results demonstrated that the 15% BiOCl/PANI hybrid exhibits excellent photocatalytic activity, degrading 97% of Rh-B and 77% of TC with a high rate constant (for Rh-B 0.0236 min−1 and for TC 0.0106 min−1). Trapping experiments highlighted that O2•− radicals play a vital role in the photodegradation mechanism. The reusability studies confirmed the good stability of the catalyst for the degradation of Rh-B (~85%) after five sequential runs. Considering its superior properties and ease of preparation, the synthesized photocatalyst can be used for ecological remediation.

Multiwalled carbon nanotubes/zeolite composite for dye degradation under sunlight

MWCNT/Zeolite composite was successfully obtained by growing multiwalled carbon nanotubes over natural zeolite chabazite using chemical vapor deposition (CVD). The structural and morphological properties were studied using Raman spectroscopy, scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The growth of the MWCNTs on the natural zeolite exchanged with Fe and Ni was observed, which functioned as a catalyst. A higher number of structural defects was found in the nanotubes grown on the zeolite than in the commercial and pure nanotubes grown by CVD. The photocatalytic/adsorption performance of the composite was determined by following the methylene blue (MB) degradation under sunlight irradiation and dark conditions. UV–VIS spectra analysis showed that MWCNT/Zeo composite removes MB dye faster than pure MWCNT and commercial multiwall carbon nanotubes (MWCNT-Sigma). The results indicate that the MWCNT/Zeo composite's removal activity increased in the presence of natural sunlight irradiation, showing a dye discoloration of up to 98% in 210 min, with an estimated apparent rate constant of the first-order kinetics (kapp) = 1.67 × 10−2 min−1.

Photochemical degradation mechanisms and ecotoxicity of propranolol in natural water under simulated and natural sunlight irradiation

The widespread use of propranolol (PRO) has led to its detection in all types of natural water bodies, and it is hazardous to both aquatic organisms and humans. In this study, the photochemical transformation of PRO in the natural environment was investigated using both simulated and outdoor light experiments. The photodegradation of PRO was found to be faster in Pearl river water and the dissolved organic matter (DOM) solutions than that in pure water under sunlight irradiation. Quenching experiments show that the excited triplet states DOM (3DOM*) played a major role while ·OH and 1O2 played minor roles in PRO degradation. The secondary reaction rate constants of 3DOM* with PRO were determined to be (4.32 ∼ 6.38) × 108 M−1 s−1. DOM with high steady-state concentrations of the generated reactive species has higher photochemical reactivity for PRO photodegradation. Total of seven products were identified in in pure water, Pearl River water and three DOM solutions. The degradation of PRO can be mainly through hydroxyl addition, dehydration, naphthalene removal and isopropyl removal reactions. The reaction sites predicted by frontier electronic density calculations can further infer degradation pathways. The ecotoxicity of degradation products was found to be decreased relative to PRO through Ecological Structure Activity Relationship (ECOSAR) program.

Photocatalytic removal of imidacloprid containing frequently applied insecticide in agriculture industry using Co3O4 modified MoO3 composites.

Water pollution caused by the frequent utilization of pesticides in the agriculture industry is one of the major environmental concerns that require proper attention. In this context, the photocatalytic removal of pesticides from contaminated water in the presence of metallic oxide photocatalysts is quite in approach. In the present study, Orthorhombic MoO3 has been modified with varying amount of cobalt oxide through wet impregnation for the removal of imidacloprid and imidacloprid-containing commercially available insecticide. The solid-state absorption response and band gap evaluation of synthesized composites revealed a significant extension of absorption cross-section and absorption edge in the visible region of the light spectrum than pristine MoO3. The indirect band gap energy varied from ∼2.88eV (MoO3) to ∼2.15eV (10% Co3O4-MoO3). The role of Co3O4 in minimizing the photo-excitons' recombination in MoO3 was studied using photoluminescence spectroscopy. The orthorhombic shape of MoO3 was confirmed through X-ray diffraction analysis and scanning electron microscopy. Moreover, the presence of distinct absorption edges and diffraction peaks corresponding to Co3O4 and MoO3 in absorption spectra and XRD patterns, respectively verified the composite nature of 10% Co3O4-MoO3. The photocatalytic study under natural sunlight irradiation showed higher photocatalytic removal (∼98%) of imidacloprid with relatively higher rate by 10% Co3O4-MoO3 composite among all contestants. Furthermore, the photocatalytic removal (∼93%) of commercially applied insecticide, i.e., Greeda was also explored.