Photodegradation Process Research Articles

DyMnO3: Synthesis, Characterization and Evaluation of Its Photocatalytic Activity in the Visible Spectrum.

DyMnO3 is a p-type semiconductor oxide with two crystal systems, orthorhombic and hexagonal. This material highlights its ferroelectric and ferromagnetic properties, which have been the subject of numerous studies. Nevertheless, its photocatalytic activity has been less explored. In this work, the photocatalytic activity of DyMnO3 is evaluated through the photodegradation of MG dye. For the synthesis of this oxide, a novel and effective method was used: polymer-decomposition. The synthesized powders contain an orthorhombic phase, with a range of absorbances from 300 to 500 nm and a band gap energy of 2.4 eV. It is also highlighted that, when using this synthesis method, some of the main diffraction lines related to the orthorhombic phase appear at 100 °C. Regarding its photocatalytic activity, it was evaluated under visible light (λ = 405 nm), reaching a photodegradation of approximately 88% in a period of 30 min. Photocurrent tests reveal a charge carrier separation (e-,h+) at a 405 nm wavelength. The main reactive oxygen species (ROS) involved in the photodegradation process were radicals, OH•, and photo-holes (h+). These results stand out because it is the first time that the photodegradation capability of this oxide in the visible spectrum has been evaluated.

Carbon quantum dot implanted graphite carbon nitride nanorod with enhanced photocatalytic activity: Mechanisms, degradation pathway and DFT calculation

Graphitic carbon nitride (g-C3N4) is recognized as a promising photocatalyst for energy and environmental remediation. However, its performance has been limited by issues such as sluggish photocarrier transfer and inadequate light absorption. To address such challenges, we fabricated an innovative photocatalyst by implanting zero-dimensional carbon quantum dots (CQDs) within one-dimensional g-C3N4 nanorods. The CQD incorporation accelerated the charge separation/transfer, simultaneously, broadened the light-harvesting ability through the up-converted fluorescent properties. Density functional theory calculations were applied to gain insights into the influence of implanted CQDs on the band gap and charge behavior of CQDs/g-C3N4. Moreover, the π-π conjugation between the g-C3N4 and CQD enabled the photogeneration of charge carriers. As a result, the CQDs/g-C3N4 photocatalyst exhibited superb photocatalytic degradation under visible light irradiation, and the removal rates of tetracycline (TC) was 94.3%, surpassing that of pure g-C3N4 by 1.2 times. Additionally, CQDs/g-C3N4 processed excellent reusability and mineralization for TC degradation. The photocatalytic degradation pathway of TC was proposed using LC-MS. Mechanisms studies revealed that the photogenerated holes (h+), hydroxyl (•OH) and superoxide radicals (•O2–) were the primary reactive species responsible for driving the photodegradation process. This study provided a valuable strategy for the design of efficient and stable photocatalysts for antibiotic wastewater remediation.

Distinguishable photocatalytic activity of nano polyaniline with quantum dots metal oxide as photocatalysts for photodegradation of Dianix blue dye and different industrial pollutants

Nanopolyaniline (PAN) polymers have recently been under active investigation as promising photocatalysts. In this work, a simple modified sol–gel method is used to make nano PAN polymers, and a chemical polymerization method is used to make nano polyaniline titanium dioxide quantum dots (PAN-TiQD) polymers as an active photocatalyst during the photodegradation of Dianix blue dye as an organic pollutant under xenon light. The traditional colloidal sol–gel method and the microwave-assisted hydrothermal method were used to make TiQD, which was then mixed with nanoPAN to make PAN-5 % TiQD (W/W) nanocomposites. Characterizations like XRD, FTIR, UV and visible diffuse reflectance spectra, TGA, surface area, EDX, and TEM were used to characterize the nanoPAN and PAN-TiQD that were made. Also, the photocatalytic activity of all synthesized polymers was investigated by the photodegradation process of Dianix blue dye as an organic hazardous pollutant in aqueous medium using a xenon photoreactor with an initial power of 75 W/Cm2. The effects of irradiation time and photocatalyst type on the photodegradation process efficiency of Dianix blue dye were examined. After 3 h of photodegradation processes, the photodegradation efficiency of PAN-TiQD reached 69 % compared to 36 % of nanoPAN due to the fact that it contains 5 % TiQD as a highly active catalyst, which reached 91 %. As an added value for this study, a significant contribution is the examination of eight hazardous industrial wastewater samples, which were assessed under direct sunlight and were in accordance with the KSA environmental permissible limit of 1000 ppm.Finally, the recycling processes in the presence of all synthesized catalysts were investigated and evaluated six times. The photodegradation rate of the recycling processes of Dianix blue dye was highly decreased in the presence of nano PAN than PAN-TiQD, while it had a low decreasing percentage in the case of TiQD. The recycling process using sunlight for industrial pollution samples was investigated at one of the KSA textile plants by using six synthetic catalysts and assessing COD and TOC values.

Engineering anisotropic silver nanoparticles/TiO2 nanocomposites and its photodegradation process optimization under polychromatic light irradiation

AbstractIn this work, we engineered the functionalization of titanium dioxide (TiO2) with silver nanoparticles (AgNP) of different morphologies aiming the application of TiO2/AgNP nanocomposites as a smart photocatalytic material for environmental purposes. The characterizations confirmed TiO2‐Ag Schottky barrier formation, which allows the electron transfer process at the materials interface, increasing charge carriers lifetime. The photocatalysis process using methyl orange as a pollutant model in water and polychromatic Hg lamp was first maximized using factorial design statistics. Photodegradation kinetic evaluations showed that the nanocomposites were up to nine times more efficient than bare TiO2. The results show that dependence on AgNP size does not follow simple rules, while anisotropic AgNPs promoted higher efficiencies. Mechanism evaluation shows that photocatalysis occurred by three main routes: i) photoreduction of pollutant adsorbed on TiO2 surface; ii) reduction by radical superoxide; and iii) by hot electrons back injection on TiO2 conduction band. The effects ii and iii occurred preferentially at anisotropic nanostructures corners. In this scenario, photodegradation rates followed the order rod≥prisms>spheres. Therefore, this work systematic evaluated the influence of nanoparticle's morphology in the photocatalytic power of a TiO2/AgNP and points anisotropic AgNP‐functionalized nanocomposite as a promising nanomaterial for further environmental applications.

All-solid-state Z-scheme nanojunction PW12/Ag/ZnO photocatalyst: Effective carriers transfer promotion and enhanced visible light driven

By coupling two semiconductors with favorable band gap, ZnO (PS I) and Keggin-type tungstophosphate (PW12, PS II), an interesting all-solid-state Z-scheme photocatalyst PW12/Ag/ZnO has been designed and synthesized. In the developed composite PW12/Ag/ZnO, noble metal silver nanoparticle as an efficient conductor constructs an efficient spatial charge separation and carriers transfer process. By controlling reaction conditions, the UV–Vis absorption of Ag nanoparticles in the designed all-solid-state Z-scheme complex is gradually improved from about 400 nm to near infrared region. Benefited from its effective visible light absorption, the developed photocatlyst exhibits favorable UV-visible response, enhanced photocatalytic performance with optimum photodegradation of PW12/Ag-4/ZnO-6 for model dye (RhB ca. 99.93% at pH=6) and high reaction kinetics. Results show that the migration pathway of the charge carriers in this ternary system is significantly altered in counterparts of binary catalysts PW12/Ag and PW12/ZnO. The synergy catalysis interaction occurs between ·OH and ·O2− during the photodegradation process of PW12/Ag/ZnO composites. This work offers insights into the construction of efficient and stable all-solid-state Z-scheme heterostructures based on POMs.

Efficient green light-based photocatalytic removal of bilirubin by a biocompatible nanocomposite of nitrogen doped graphene quantum dots/Au

Nitrogen-doped graphene quantum dots/Au (NGQDs/Au) nanocomposite was synthesized by hydrothermal method followed by a photochemical route. The gram-scale nitrogen-doped graphene quantum dot was synthesized by using hydrothermal method from urea and citric acid as a precursor. By adding HAuCl4 to the prepared sample, the nitrogen-doped graphene quantum dots/Au nanocomposite was made in a straightforward photochemical process. The synthesized composite was utilized directly as a biocompatible photocatalyst for bilirubin degradation under green light irradiation.The nanocomposite was characterized using FESEM, Raman, XRD, TEM, UV–Vis spectroscopy, and PL. The quantum yield of the nanocomposite was calculated. The role of surface plasmon resonance (SPR) of Au nanoparticles in reduction of the quantum yield and quantum yield effect on the photodegradation process was investigated. The photocatalytic degradation efficiency of bilirubin in presence of the synthesized nanocomposite was measured to be nearly 74.7 % after 100 min green light irradiation, which is 5 times more than blue light used in clinical phototherapy without any photocatalyst. The optical analysis results reveal that the doping of nitrogen in GQDs and compositing with gold could accelerate the suppression of charge carrier's recombination. The future application of biocompatible photocatalysts in jaundice treatment under the green light irradiation was also approved in this research.

Synthesis of SmMnO3/Sm2O3 nanocomposites as efficient photocatalysts for organic dye degradation by sol gel pechini method

In this research, we present SmMnO3/Sm2O3 nanocomposites as a novel ferromagnetic photocatalyst, synthesized through a straightforward sol-gel Pechini method utilizing citric acid and oxalic acid as fuels. Achieving the desired morphology involved varying the fuel type and calcination temperature. Comprehensive physicochemical characterizations were conducted using X-ray diffraction analysis (XRD), scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS), transmission electron microscopy (TEM), Fourier-transform infrared spectroscopy (FTIR), vibrating sample magnetometer (VSM), diffuse reflectance spectroscopy (DRS), and Brunauer-Emmett-Teller BET. With a band gap of 2.1 eV in the visible range, the SmMnO3/Sm2O3 nanocomposites exhibit promising optical properties. The photocatalytic prowess of these nanocomposites was systematically assessed against Malachite Green and Acid Red, with optimization of key parameters such as light source, pollutant concentration, and catalyst dosage. Notably, the peak photocatalytic activity was observed for Malachite Green, achieving an impressive 96% degradation under visible light within 120 min. The elucidation of the photocatalytic mechanism employed scavengers, revealing the pivotal role of OH• in the photodegradation process. Recycling experiments demonstrated consistent and acceptable results over five cycles, affirming the recyclability and durability of the SmMnO3/Sm2O3 nanocomposites. This study introduces a novel ferromagnetic photocatalyst with notable photocatalytic efficiency, emphasizing its potential applications in environmental remediation. The novelty of this work lies in the introduction of a new nanocomposite for photocatalysis in visible light, achieving high efficiency within a short time frame of 120 min.

Study of amur cork tree bark extract-dyed paper under artificial UVA irradiation

Some ancient Chinese paper artifacts dyed with amur cork tree bark extracts are currently preserved to different extents in museums and libraries worldwide. As traditional natural plant dyes, the long-term performance of the amur cork tree bark extract-dyed handmade paper has been questioned under a preserved environment. The photodegradation process of the extract-dyed papers was examined under accelerating artificial UVA irradiation conditions according to China national standard-paper and board- accelerated aging (exposure to light). Changes during aging were analyzed by optical observation and scanning electron microscopy (SEM), X-ray diffraction (XRD), thermogravimetric analysis (TGA), Fourier transform infrared spectrometry (FTIR), pH, and tensile strength and folding endurance tests. The results showed that the main components from extracted dyes played an important role in affecting the photodegradation properties of dyed paper. The changes in surface color, pH, morphology and mechanical properties after the artificial UVA accelerated degradation tests revealed that a suitable concentration of the extract dyes for maintaining the long-term irradiation stability of the paper is important.

Investigating the Influence of Precursor Concentration on the Photodegradation of Methylene Blue using Biosynthesized ZnO from Pometia pinnata Leaf Extracts

The ZnO nanoparticles were synthesized at various precursor concentrations i.e. 0.05, 0.1, and 0.5 M by biosynthesis method based on Pometia pinnata Leaf Extracts. Initial nanoparticle concentration influenced the optical bandgap, shape, and structure of nanoparticles. The photodegradation process was carried out under UV illumination. The efficiency of MB degradation was determined by measuring the decrease in MB concentration and by analyzing the optical absorption at 663 nm recorded by UV-Vis spectroscopy. Results showed that the biosynthesized ZnO nanoparticles exhibited efficient photodegradation of MB, with a maximum degradation rate of 80% after 90 minutes of exposure to UV-C light. The study highlights the potential of Pometia pinnata leaf extracts as a low-cost and eco-friendly alternative for synthesizing ZnO nanoparticles for use in environmental remediation processes

Photocatalytic degradation of aqueous Congo red dye pollutants by rare-earth metal oxide (CeO2) nanorods

Existing nano powder-based photocatalysts face challenges in degradation performance, particularly for the degradation of complex dyes like Congo red (CR). In this work, cerium dioxide (CeO2) nanorods are successfully fabricated combining hydrothermal synthesis with calcination for the photocatalytic degradation of CR dyes. The synthesized CeO2 nanorods possess a diameter of ∼ 100 nm based on field emission scanning electron microscopy (FE-SEM) investigation. The atomic percentages of Ce and O elements are measured to be 44.2 at% and 39.2 at%, respectively, by the energy dispersive X-ray spectroscopy (EDS). By means of X-Ray diffraction (XRD) analysis, all the prepared samples show cubic CeO2 with a small amount of Ce2O3. To validate their photocatalytic function, the CeO2 nanorods are tested towards CR dyes, where the degradation of CR solution under UV irradiation is faster than that in dark condition. A high CR degradation efficiency of up to 97.7% is revealed within 130 min photocatalytic activity. From the scavenger test, superoxide radical (•O2–) and hole (h+) are discovered to be the most reactive oxygen species generated during photodegradation process. This finding provides a simple yet effective method to fabricate highly effective photocatalytic materials for dye pollutant degradation in wastewater treatment. Future work will focus on optimizing the material properties and degradation mechanisms further, opening avenues for the scaled application of these materials.

Magnetic perovskite nanohybrid based on g-C3N4 nanosheets for photodegradation of toxic environmental pollutants under short-time visible irradiation

In this study, a magnetic perovskite nanohybrid based on g-C3N4 (gCN) nanosheets was synthesized and developed for the efficient photodegradation of toxic environmental pollutants under short-time visible irradiation. The synthesis of this nanohybrid involved the incorporation of SrTiO3:N (STO:N) and ZnFe2O4 (ZnF) onto the g-C3N4 nanosheets through a simple reflux method. Our investigation encompassed a comprehensive suite of analytical techniques, including BET, TGA, TEM, SEM, EDX, DRS, VSM, XRD, photocurrent, and FT-IR, to elucidate the physicochemical characteristics of this nanocomposite in the context of its application in photodegradation processes. The nanohybrid displayed significantly enhanced photocatalytic activity compared to its individual components, achieving a degradation efficiency of over 90% for various pollutants, including organic dyes like Rhodamine B (Rh-B), within a short irradiation time. This enhanced activity can be attributed to the synergistic effect between gCN, STO:N, and ZnF, which promotes the generation of reactive oxygen species and facilitates the degradation process. Notably, the nanocomposite containing 20 wt% STO:N perovskite and 20 wt% ZnF demonstrated the highest Rh-B degradation rate under visible light irradiation within just 30 min. Furthermore, the nanohybrid displayed excellent stability and reusability over seven consecutive runs, retaining its high photocatalytic activity even after multiple cycles of degradation. This remarkable performance can be attributed to the strong interaction between the gCN nanosheets and the magnetic perovskite components, which prevents their aggregation and ensures their efficient utilization. Additionally, the nanohybrid exhibited excellent visible light absorption, enabling the utilization of a wider range of light for degradation. This feature is particularly advantageous, as visible light is more abundant in sunlight compared to UV light, rendering the nanohybrid suitable for practical applications under natural sunlight. In conclusion, the ternary gCN-STO:N@ZnF nanocomposite represents a promising candidate for the treatment of organic pollutants in aqueous environments, offering a versatile and efficient solution.

Assessing the efficacy and mechanisms of glycol-contaminated water treatment through floating treatment wetlands

Abstract The growing concerns surrounding water pollution and the degradation of ecosystems worldwide have led to an increased use of nature-based solutions (NbSs). This study assessed the feasibility of using floating treatment wetlands (FTWs) as an NbS to treat propylene glycol-contaminated water and quantitatively investigated different removal pathways. With an environmentally relevant concentration of propylene glycol (1,250 mg/L), FTWs containing Acorus calamus and mixed species demonstrated the highest average glycol mass removal efficacy (99%), followed by Carex acutiformis (98%), Juncus effusus (93%), and the control group without plants (10%) after 1 week. Additional mesocosm-scale experiments with varying FTW configurations, including surface coverage to reduce evaporation and photodegradation processes, and the addition of antibiotics to inhibit microbial activity, were conducted to quantify glycol removal pathways. Mass balance analysis results revealed that microbial biodegradation (33.3–39.7%) and plant uptake (37.9–45.2%) were the primary pathways for glycol removal. Only 15.5–19.5% of the glycol removal via evaporation and photodegradation was accounted in this study, which may be attributed to the mesocosm experimental setup (static water and no wind). Aligned with the broader discussion regarding biodiversity improvements and carbon storage capacity, this study demonstrated that FTWs are an environmentally friendly and effective NbS for addressing glycol-contaminated water.

Green synthesis of three-dimensional magnesium ferrite/titanium dioxide/reduced graphene from Garcinia mangostana extract for crystal violet photodegradation and antibacterial activity

In this study, three-dimensional porous magnesium ferrite/titanium dioxide/reduced graphene oxide (MgFe2O4-GM/TiO2/rGO (MGTG)) was successfully synthesized via green and hydrothermal-supported co-precipitation methods using the extract of Garcinia mangostana (G. mangostana) as a reducing agent. The characterization results indicate the successful formation of the nano/micro MgFe2O4 (MFO) and TiO2 on the structure of the reduced graphene oxide (rGO), which can also act as efficient support, alleviating the agglomeration of the nano/micro MFO and TiO2. The synergic effects of the adsorption and photodegradation activity of the material were investigated according to the removal of crystal violet (CV) under ultraviolet light. The effects of catalyst dosage, CV concentration, and pH on the CV removal efficiency of the MGTG were also investigated. According to the results, the CV photodegradation of the MGTG-200 corresponded to the pseudo-first-order kinetic model. The reusability of the material after 10 cycles also showed a removal efficiency of 92%. This happened because the materials can easily be recollected using external magnets. In addition, according to the effects of different free radicals ·O2 −, h+, and ·OH on the photodegradation process, the photocatalysis mechanism of the MGTG was also thoroughly suggested. The antibacterial efficiency of the MGTG was also evaluated according to the inhibition of the Gram-positive bacteria strain Staphylococcus aureus (S. aureus). Concurrently, the antibacterial mechanism of the fabricated material was also proposed. These results confirm that the prepared material can be potentially employed in a wide range of applications, including wastewater treatment and antibacterial activity.

Poly(vinyl alcohol)-tragacanth gum/Titania bio-nanocomposite film for photodecomposition of malachite green

Concerned about the contamination as a consequence of untreated wastewater worldwide, nanomaterials have been utilized for purification. Nevertheless, their separation from water is difficult after the treatment. Herein, Titania nanomaterials were embedded in a poly(vinyl alcohol)-tragacanth gum (PVA-TG) matrix, due to easy separation. The polymer matrix was cross-linked by a green agent of citric acid, and the physicochemical properties of PVA-TG/Titania bio-nanocomposite (bio-NC) films were characterized, which displayed a high swelling ratio in the water because of the addition of TG. Further, Titania nanomaterials illustrated a cube-like shape in the PVA-TG/Titania bio-NC film confirming the complete dispersion. Afterward, the photodecomposition of malachite green (MG) over this bio-NC film was studied and optimized under ultraviolet (UV) irradiation. Scavenger agents determined that the electron was produced more than other radical agents. Ultimately, the photodegradation process of MG over bio-NC films was suggested by the hydroxyl addition, singlet oxygen, and UV irradiation transformation pathways.

Facile Preparation of PVDF/CoFe2O4-ZnO Hybrid Membranes for Water Depollution.

In this investigation, CoFe2O4-PVDF and CoFe2O4-ZnO-PVDF hybrid membranes were prepared using a modified phase inversion method in which a magnetic field was applied during the casting process to ensure a uniform distribution of nanomaterials on the membrane surface. Thus, better absorption of light and increased participation of nanoparticles in the photodegradation process is ensured. The influence of nanomaterials on the crystalline structure, surface morphology, and hydrophilicity properties of the PVDF membrane was investigated. The obtained results indicated that the hybrid membrane exhibited significant differences in its intrinsic properties due to the nanomaterials addition. The hydrophilicity properties of the PVDF membrane were improved by the presence of nanoparticles. The photocatalytic decomposition of aqueous Rhodamine B solution in the presence of the prepared membrane and under visible light irradiation was tested. The hybrid membrane containing CoFe2O4-ZnO on its surface exhibited a high removal rate.

NGO/ZnO2/ZnO heterojunctions with self-accelerating photocatalysis for efficient degradation of organic dyes

Photocatalytic degradation of dyes using semiconductor materials has received widely attention. We employed ZnO2 as a zinc source and synthesized NGO/ZnO2/ZnO heterojunctions with self-accelerated photocatalytic function by hydrothermal technique and investigated their photocatalytic degradation performance of RhB and MO under simulated sunlight irradiation. NGO greatly improved the adsorption performance of NGO/ZnO2/ZnO on dyes, among which, the adsorption of MO dyes was 11 times higher than that of ZnO2/ZnO. While enhancing the sunlight absorption range and adsorption performance, the NGO could also rapidly transfer electrons and effectively inhibit the complexation of electron-hole pairs, further improving the photocatalytic performance. By optimizing the doping ratio of NGO, NGO/ZnO2/ZnO with the highest photocatalytic degradation activity was obtained, which was 4.4 times higher than that of ZnO2/ZnO. In addition, the acid-base resistance and cycling experiments showed that the NGO/ZnO2/ZnO-3 photocatalyst had good stability. The EPR experiments showed that ·O2− and ·OH radicals were extremely important active substances in the whole photodegradation process. Finally, the synergistic enhancement mechanism of the photocatalytic performance of ZnO by NGO and ZnO2 was revealed. This work provides a good strategy for designing ZnO composite photocatalysts to efficiently degrade organic dyes.

Deposition of SnS thin films on various substrates at room temperature

This study describes a modified SILAR technique for depositing Tin monosulphide (SnS) thin films on diverse substrates, such as glass, ITO coated glass, and OHP sheet, all at room temperature. This simple, less expensive, environmentally friendly, and industrially scalable method allows excellent control over the deposition rate and thickness, as well as many experimental flexibilities. The advantages of depositing films at room temperature include energy efficiency, cost-effectiveness, and suitability for heat-sensitive materials. The deposited SnS thin films underwent comprehensive analysis through XRD, FESEM, EDAX, XPS, TGA, and UV–visible spectroscopy to thoroughly understand their properties. The results showed that the films were polycrystalline, orthorhombic, single-phase, and nearly stoichiometric, with a bandgap value in the visible region. The deposition conditions were optimized to achieve high-quality thin films, and the impact of substrate variations on film characteristics was also investigated. The study showcased the simplicity of doping in the modified SILAR process. Furthermore, the study demonstrated the photocatalytic degradation effectiveness of SnS thin films against the dye Rhodamine B. Various analyses, including UV-visible spectroscopy studies, ROS scavenger tests, ROS indicator tests, and kinetic analysis, were performed. The photodegradation process was effectively described by the Langmuir-Hinshelwood (L-H) mechanism.

Plant leaves extract assisted eco-friendly fabrication of ZnO-SnO2@Chitosan for UV-induced enhanced photodegradation of single and ternary mixtures of Rhodamine B

The inadequate handling and uncontrolled discharge of organic dyes into aquatic environments can result in elevated toxicity levels and have adverse effects on both human health and the overall ecosystem. The present work investigated the photodegradation efficiency of the ZnO-SnO2@chitosan nanocomposite (NC) for Rhodamine B (RhB) under ultraviolet (UV) irradiation. The ZnO-SnO2@chitosan nanocomposite (NC) was synthesized via a simple, eco-friendly, and less energy-intensive route, i.e., the co-precipitation method. The synthesized NC was extensively characterized using X-ray diffraction (XRD), Fourier transform-infrared spectroscopy (FTIR), UV–Vis spectroscopy, Brunauer-Emmett-Teller (BET) analysis, field emission scanning electron microscope (FE-SEM), energy dispersive X-ray (EDX) spectroscopy, and UV-Vis diffuse reflectance spectroscopy (UV-Vis DRS). The chitosan-modified nanocomposite (NC) exhibits a moderate surface area of 79 m2/g with a low band gap value of 2.72 eV. The photodegradation process depended on operational parameters, such as pH, irradiation time, temperature, dye concentration, and dosage of the photocatalyst. The degradation data of RhB dye was interpreted through a kinetic model, and the data agreed well with the pseudo-first-order kinetics. The rate constant values deciphered from the kinetic model were found to fall in the range of 0.0281–0.0182 min–1 for 25–100 mg/L of dye concentration, suggesting that the synthesized photocatalysts facilitate the dye mineralization process by reducing the activation energy barrier. The interpretation of the reaction intermediates was accomplished with the help of a GC-MS profile to understand the underlying reaction mechanism. The photodegradation potential of the synthesized NC was explored for individual dyes such as RhB, MB and CV and the mixed dye system (RhB+MB+CV). The NC performs better for individual dyes (RhB, CV, and MB), and the degradation performance diminished slightly in the case of mixed dye solution. The reusability study of the synthesized nanocomposites portrayed the successful utility of the recycled NC up to four times without any significant loss in the degradation capacity, thus making the overall degradation process economical and sustainable. The E–factor (a green chemistry metric) study infers that the NC synthesis process imposes no significant threat to the environment and can be safely used in wastewater treatment.

Do Microplastics Affect the Photodegradation of Duloxetine and Its Phototoxicity to Protozoan Spirostomum ambiguum (Müller, 1786) Ehrenberg, 1835?

As contaminants are often present in aquatic environments as mixtures, they may interact with each other and affect living organisms differently than when tested individually. Emerging pollutants such as pharmaceuticals and microplastics can be influenced by various environmental factors, with UV/Vis radiation being among the most significant. This study aimed to evaluate the photodegradation of the antidepressant duloxetine in the presence of four types of microplastics. Acute toxicity was tested using the Spirotox assay, duloxetine concentration was determined using HPLC-DAD analysis, and the resulting photodegradation products were tested using HPLC-MS/MS. Following 1 and 2 h of exposure in a sunlight simulator, the concentrations of duloxetine decreased by nine and thirteen times, respectively, while its toxicity to protozoa decreased by only two and three times. The presence of microplastics in the samples did not affect either the photodegradation process or the toxicity of duloxetine. HPLC-MS/MS analysis revealed the presence of 34 duloxetine photodegradation products. In silico toxicity analysis using the T.E.S.T. program for the protozoan Tetrahymena pyriformis indicated that one-third of the photoproducts were as toxic, and two products were found to be much more toxic than duloxetine. The high toxicity of one of these compounds was confirmed using the Spirotox test.

Amorphous iron oxyhydroxides nano precursors used for Reactive Yellow 84 removal from aqueous solutions

In this research, we investigated the potential use of amorphous iron oxyhydroxides, ferrihydrite (FHY), for the removal of persistent pollutants from aqueous solutions. Ethylenediaminetetraacetic acid (EDTA) and ethylenediamine-N, N′-disuccinic acid (EDDS) were used as complexing agents during synthesis aiming to enhance the FHY properties. Synthesized materials were characterized by X-ray diffraction, SEM and TEM Microscopy, N2 sorption/desorption, and FT-IR Spectroscopy for their mineralogy, crystallinity, morphology and size, surface properties, and the organic content in their structure. The addition of chelating agents led to differences in nanoparticles morphology, amorphic degree, and surface properties. Reactive Yellow 84 dye was chosen as a representative refractory pollutant and laboratory-scale adsorption studies were conducted at varying dye concentrations. Ca. 100 % RY 84 dye removal efficiency was achieved within one hour at dye concentrations of 5–10 mg/L for an adsorbent dosage of 1 mg/L FHY. Adsorption kinetics and isothermal studies were considered, the uptake capacity was calculated for each nanomaterial and empiric mechanistic information was derived. The results showed that ferrihydrite exhibits the best performance, with a maximum uptake capacity of 40.73 mg Reactive Yellow 84 dye per gram adsorbent followed by FHY_EDTA and FHY_EDDS (up to 35.86 mg/g). Coupling the adsorption with photodegradation processes led to a significant increase in removal efficiencies of persistent RY 84 from polluted aqueous solution, in good timing, suggesting a feasible alternative at sites where dye concentration in effluents is elevated.