Photooxidation Research Articles

Suppressing Effect of Flavonoid Compounds on Lipids Photooxidation of Sheep Red Blood Cells and Oleic Acid Photooxidation

ABSTRACTPhotosensitizers and pigments in raw meat such as porphyrins, riboflavin, and myoglobin after incorporation with light beam prompt the generation of singlet oxygen (1O2) from triplet oxygen (3O2) and cause oxidative rancidity of meat products. In this study, the results of photooxidation reactions of sheep erythrocyte (red blood cell) model as a model rich in hemoglobin and phospholipids bilayer, and oleic acid model were obtained by 1H NMR spectroscopy, TBARS assay, and iodometric titration. In both models, the rate of lipid photooxidation in the presence of hydroalcoholic extracts of Turmeric (Curcuma longa L.) and Cumin (Cuminum cyminum L.) as natural antioxidants, Butyl hydroxytoluene (BHT) as a synthetic antioxidant, and sodium azide (NaN3) as a well‐known 1O2 scavenger were decreased in the order of NaN3 > Turmeric > Cumin > BHT. It was proven that during the photooxidation process, there is a direct association between the amount of flavonoid compounds and 1O2 scavenging.

Effects of photooxidation exposure time on the modification of cassava starch: a comprehensive study on chemical, functional, structural, and morphological properties

Photooxidation is one of the green technologies that can be used to modify starch. This process produces oxidized starch which induces alterations in the starch structure and functional properties. Photooxidation of starch can be influenced by hydrogen peroxide concentration, exposure time, slurry concentration, ultraviolet (UV) intensity, addition of lactic acid, and temperature. This study aims to evaluate the effect of photooxidation exposure time on the chemical, functional, structural, and morphological properties of cassava starch. Cassava starch was modified using a UV catalysator reactor and treated with photooxidation using a combination of hydrogen peroxide and UV irradiation for 15, 30, and 45 min. The result showed that the longer exposure time produced starch with higher amylose, carboxyl contents, solubility, water absorption capacity, oil absorption capacity, and color L*. Moreover, the longer time of the photooxidation process caused a decrease in the pH value, swelling power, and pasting properties. Photooxidation decreased the relative crystallinity values and damaged the granule morphology of the modified cassava starch. These results showed that photooxidation successfully modified cassava starch.

Porous Bimetallic Ti-MOFs for Photocatalytic Oxidation of Amines in Air.

A family of microporous titanium-containing metal-organic frameworks (denoted as M2Ti-CPCDC, M = Mn, Co, Ni) has been synthesized by using a bimetallic [M2Ti(μ3-O)(COO)6] cluster and a tritopic carbazole-based organic ligand H3CPCDC. M2Ti-CPCDC are stable and display permanent porosity for N2 and CO2 uptake, ranking among the most porous titanium-based metal-organic frameworks. M2Ti-CPCDC crystals exhibit n-type semiconductor behavior. Further catalytic studies demonstrate that all M2Ti-CPCDC materials are applicable for triggering photo-oxidative reactions of amines in air. More specifically, amines with electron-donating groups afford the aldehydes as the main products, while amines bearing electron-withdrawing groups give rise to imines as the main product. Among them, Mn2Ti-CPCDC exhibit the best photocatalytic activity, with conversion of benzylamine up to 99% and selectivity of 99%. Mn2Ti-CPCDC could be recycled in at least three runs while retaining crystallinity and catalytic activity. The reaction mechanism indicates that photoinduced hole (h+), superoxide radical anion (O2·-), and singlet oxygen (1O2) are the main active species involved in the photo-oxidation process.

Cefadroxil photodegradation processes sensitized by natural pigments: mechanistic aspects and impact on the antimicrobial function.

Cefadroxil is a widely used antibiotic with a low elimination efficiency in wastewater treatments plants, so it represents a contaminants of emerging concern that should be removed. The photosensitization process that involves natural pigments and visible sunlight can be offered as an environmentally friendly alternative to be considered for Cefadroxil degradation. In this investigation, we carried out a mechanistic and kinetic approach to Cefadroxil photodegradation sensitized by Riboflavin and Humic Acid, in individual and combined processes. Our experiments indicate that Cefadroxil is able to interact with the excited states of Riboflavin as well as with the photogenerated reactive oxygen species, with an important contribution of singlet oxygen. The antibiotic was less sensitive to the photodegradation in the presence of Humic Acids and in the mixture of Riboflavin and Humic Acids. Self-sensitization processes and internal filter effects are proposed as possible explanations for the observed phenomenon. The reaction between Cefadroxil and singlet oxygen showed a dependence with the pH of the medium, the photodegradation kinetic constants are greater at alkaline pH compared to neutral pH. The reaction is favored when the anionic species of the antibiotic is present. Microbiological tests on S. aureus indicated that the antibiotic reduce its antimicrobial activity as a consequence of the photooxidative process mediated by singlet oxygen. We believe that the results are relevant since, the sensitized photodegradation process could lead to the oxidation of Cefadroxil and to the progressive loss of its antimicrobial function, this fact could contribute to the decrease in the generation of bacterial multi-resistance to antibiotics in the environment.

A convenient strategy for mitigating microplastics in wastewater treatment using natural light and ZnO nanoparticles as photocatalysts: A mechanistic study

Polypropylene microplastics (PPMPs) are one of the major emerging contaminants in the ecosystem due to their frequent usage and improper disposal practices. These PPMPs enter ecosystems via wastewater effluent plants and cause severe environmental health issues. In addition, quantifying PPMPs smaller than 50 μm in wastewater plant extraction is very difficult. Thus, the current study was designed to mitigate the PPMPs using zinc oxide nanoparticles (ZnONPs) as a photocatalyst under sunlight. The photocatalytic reaction was examined using spectroscopic techniques and microscopic imaging. The findings indicated that the weight loss percentage of PPMPs increased, and a decrease in UV–Vis DRS peak intensities was observed. The spectroscopic results elucidated the formation of free radicals, which affect the PPMPs and lead to the formation of carbonyl, allylic, and unsaturated groups. Further, EDS reports clarified that there is increased oxygen content due to the photooxidation process and the disintegration of the polymer chain owing to decreased carbon levels. Overall, ZnO photocatalyst absorbs photons from the visible spectrum of sunlight and forms free radicals, which affect the PPMPs to initiate polymer deterioration. Also, the current study revealed the mechanistic pathway of PPMP degradation under the photocatalytic reaction as proposed in the results obtained above.

ADDITIONAL PURIFICATION BY ULTRAVIOLET RADIATION OF RED SPD DYE AFTER ELECTROCHEMICAL DESTRUCTION

Surface water pollution by industrial wastewater is one of the serious environmental problems of the Republic of Uzbekistan. A significant source of pollution is the textile industry, whose wastewater contains organic dyes and various related substances. This article presents the results of a study of the photooxidation of the active dye Red SPD after electrochemical degradation in an electrolytic cell with insoluble anodes. Studies have been carried out to determine the efficiency of active chlorine synthesis in the process of electrolysis of chloride solutions, the effect of active chlorine concentration, electrolyte composition, power consumption when using the combined electrochemical/ultraviolet irradiation process, and changes in the spectral characteristics of the dye solution for carrying out the photooxidation process have been studied. The technological parameters of the method of photooxidative post-treatment in treated water after electrochemistry are established, considering the concentration of oxidizing agents. The maximum current output of active chlorine occurs at a treatment time of 10 minutes. The use of NaCl as an electrolyte in comparison with Na2SO4 showed the best result in the purification process. When using NaCl with a concentration of 1.625 g L-1 in the composition of a sulfate-containing electrolyte, it can reduce the concentration of Red SPD to 1.0 mg L-1. Photooxidative degradation can become an alternative for post-treatment of wastewater from textile enterprises. The developed technology confirms the efficiency of using the combined cleaning method.

Porous Metal Organic Framework (MOF) derived dimorphic (n-ZnO/p-NiO) Z-scheme heterojunction anchored with MWCNTs (ternary nano-architecture): A novel approach for optimization of photodegradation mechanism and kinetics of Congo red (CR) dye

Global efforts to combat water pollution, especially from organic dyes like Congo red, emphasize the use of advanced nanomaterials for sewage purification. Metal-Organic Frameworks (MOFs), known for their crystalline structures and versatile properties, have become pivotal in wastewater treatment research. Integrating MWCNTs into MOF derived composite nanostructures is a strategic advancement, boosting the efficiency of photocatalytic systems and addressing environmental concerns. This study details the synthesis of a novel Z-scheme heterojunction nanocomposite (n-ZnO/p-NiO) incorporating multi-walled carbon nanotubes (MWCNTs), achieved via a solvothermal method using metal-organic framework (MOF) as a template. The study uses XRD, FTIR, FESEM, BET, UV, and PL for comprehensive nanocomposite characterization, offering insights into its structural, morphological, and optical properties. The resultant nanocomposite displays high surface area, sturdy pore arrangement, and consistent morphology. MWCNTs influence crystal growth and optical absorption, enhancing surface hydroxyl group concentration and acting as electron acceptors. This results in decreased photo oxidation and improved overall stability under light exposure in the composite. The composite achieves 92 % Congo red degradation in 60 min under UV light, showcasing superior dye adsorption capacity. This underscores its potential as an efficient photocatalyst for environmental remediation and wastewater treatment.

Tunable multicolor supramolecular assemblies based on phosphorescence cascade energy transfer for photocatalytic organic conversion and anti-counterfeiting

Making full use of the captured energy by phosphorescence light-harvesting systems (PLHSs) and the tunable photoluminescence in energy transfer process to realize the multiple applications is still the challenge of PLHSs research. In this study, we have successfully constructed a highly effective PLHS with tunable multicolor luminescence and efficient conversion of photosensitizer types, which can further be used in photocatalytic organic conversion, information anti-counterfeiting and storage. The supramolecular polymer of BDBP-CB[8], which is generated by cucurbit[8]uril (CB[8]) and 4-(4-bromophenyl)-pyridine derivative (BDBP), realizes a phosphorescence emission and a change in luminescence color. Notably, white light emission was achieved and the logic gate systems were constructed utilizing the application of adjustable luminescence color. More interestingly, PLHS can be constructed by employing BDBP-CB[8] as energy donors, Sulforhodamine 101 (SR101) and Cyanine5 (Cy5) as energy acceptors, which results in a remarkably tunable multicolor photoluminescence to achieve the information storage. Furthermore, we have also found that BDBP-CB[8] can serve as type II photosensitizer for the effective production of singlet oxygen (1O2) during the photooxidation process of styrene in aqueous environments, attaining a remarkable output rate reaching as high as 89 %. Particularly, compared with 1O2 produced by type II photosensitizer BDBP-CB[8], the construction of PLHS can effectively convert type II photosensitizer to type I photosensitizer and efficiently generate superoxide anion radical (O2•−), which can be used for photocatalytic cross-dehydrogenative coupling (CDC) reaction in the aqueous solution with a yield of 90 %. Thus, we have created a PLHS that not only achieves tunable multicolor emission for information anti-counterfeiting and storage, but also realizes the conversion of reactive oxygen species (ROS) for different types photocatalytic oxidation reactions.

Pilot scale advanced photo-oxidation processes for remediation of pharmaceutical wastewater. A case study

Pilot scale advanced photo-oxidation processes for remediation of pharmaceutical wastewater. A case study

Light Sensing beyond Vision: Focusing on a Possible Role for the FICZ/AhR Complex in Skin Optotransduction.

Although our skin is not the primary visual organ in humans, it acts as a light sensor, playing a significant role in maintaining our health and overall well-being. Thanks to the presence of a complex and sophisticated optotransduction system, the skin interacts with the visible part of the electromagnetic spectrum and with ultraviolet (UV) radiation. Following a brief overview describing the main photosensitive molecules that detect specific electromagnetic radiation and their associated cell pathways, we analyze their impact on physiological functions such as melanogenesis, immune response, circadian rhythms, and mood regulation. In this paper, we focus on 6-formylindolo[3,2-b]carbazole (FICZ), a photo oxidation derivative of the essential amino acid tryptophan (Trp). This molecule is the best endogenous agonist of the Aryl hydrocarbon Receptor (AhR), an evolutionarily conserved transcription factor, traditionally recognized as a signal transducer of both exogenous and endogenous chemical signals. Increasing evidence indicates that AhR is also involved in light sensing within the skin, primarily due to its ligand FICZ, which acts as both a chromophore and a photosensitizer. The biochemical reactions triggered by their interaction impact diverse functions and convey crucial data to our body, thus adding a piece to the complex puzzle of pathways that allow us to decode and elaborate environmental stimuli.

Enhancing textile wastewater decolorization: harnessing the power of diverse oxidants in photo-oxidation process with response surface methodology

Enhancing textile wastewater decolorization: harnessing the power of diverse oxidants in photo-oxidation process with response surface methodology

Development of a novel LED-IoT photoreactor for enhanced removal of carbamazepine waste driven by solar energy

This study introduces an innovative LED-IoT photoreactor, representing a significant advancement in response to the demand for sustainable water purification. The integration of LED-IoT installations addresses the challenge of intermittent sunlight availability, employing LEDs with a spectrum mimicking natural sunlight. Passive Infra-Red (PIR) sensors and Internet of things (IoT) technology ensure consistent radiation intensity, with the LED deactivating in ample sunlight and activating in its absence. Utilizing a visible light-absorbing photocatalyst developed through sol-gel synthesis and mild-temperature calcination, this research demonstrates a remarkable carbamazepine removal efficiency exceeding 95% under LED-IoT system illumination, compared to less than 90% efficiency with sunlight alone, within a 6-h exposure period. Moreover, the designed photocatalytic system achieves over 60% mineralization of carbamazepine after 12 h. Notably, the photocatalyst demonstrated excellent stability with no performance loss during five further cycles. Furthermore, integration with renewable energy sources facilitated continuous operation beyond daylight hours, enhancing the system's applicability in real-world water treatment scenarios. A notable application of the LED-IoT system at an operating sewage treatment plant showed nearly 80% efficiency in carbamazepine removal from sewage in the secondary settling tank after 6 h of irradiation, coupled with nearly 40% mineralization efficiency. Additionally, physicochemical analyses such as XPS and STA-FTIR confirm that the carbamazepine photooxidation process does not affect the surface of the photocatalyst, showing no adsorption for degradation products.

Antimicrobial Packaging for Plum Tomatoes Based on ZnO Modified Low-Density Polyethylene.

Food safety and quality are major concerns in the food industry. Despite numerous studies, polyethylene remains one of the most used materials for packaging due to industry reluctance to invest in new technologies and equipment. Therefore, modifications to the current materials are easier to implement than adopting whole new solutions. Antibacterial activity can be induced in low-density polyethylene films only by adding antimicrobial agents. ZnO nanoparticles are well known for their strong antimicrobial activity, coupled with low toxicity and UV shielding capability. These characteristics recommend ZnO for the food industry. By incorporating such safe and dependable antimicrobial agents in the polyethylene matrix, we have obtained composite films able to inhibit microorganisms' growth that can be used as packaging materials. Here we report the obtaining of highly homogenous composite films with up to 5% ZnO by a melt mixing process at 150 °C for 10 min. The composite films present good transparency in the visible domain, permitting consumers to visualize the food, but have good UV barrier properties. The composite films exhibit good antimicrobial and antibiofilm activity from the lowest ZnO composition (1%), against both Gram-positive and Gram-negative bacterial strains. The homogenous dispersion of ZnO nanoparticles into the polyethylene matrix was assessed by Fourier transform infrared microscopy and scanning electron microscopy. The optimal mechanical barrier properties were obtained for composition with 3% ZnO. The thermal analysis indicates that the addition of ZnO nanoparticles has increased thermal stability by more than 100 °C. The UV-Vis spectra indicate a low transmittance in the UV domain, lower than 5%, making the films suitable for blocking photo-oxidation processes. The obtained films proved to be efficient packaging films, successfully preserving plum (Rome) tomatoes for up to 14 days.

Construction of Au quantum dots/nitrogen-defect-enriched graphite carbon nitride heterostructure via photo-deposition towards enhanced nitric oxide photooxidation

The challenge of mitigating pollution stemming from industrial exhaust emissions is a pressing issue in both academia and industry. This study presents the successful synthesis of nitrogen-defect-enriched graphite carbon nitride (g-C3N4) using a two-step calcination technique. Furthermore, a g-C3N4-Au heterostructure was fabricated through the photo-deposited Au quantum dots (QDs). When subjected to visible light irradiation, this heterostructure exhibited robust nitric oxide (NO) photooxidation activity and stability. With its fluffy, porous structure and large surface area, the nitrogen-defect-enriched g-C3N4 provides more active sites for photooxidation processes. The ability of g-C3N4 to absorb visible light is enhanced by the local surface plasmon resonance (LSPR) effect of Au QDs. Additionally, the lifetime of photogenerated charge carriers is extended by the presence of N defects and Au, which effectively prevent photogenerated electron-hole pairs from recombining during the photooxidation process. Moreover, the oxidation pathway of NO was analyzed through In-situ Fourier transform infrared (FT-IR) spectroscopy and Density Functional Theory (DFT) calculation. Computational findings revealed that the introduction of Au QDs decreases the activation energy of the oxidation reaction, thereby facilitating its occurrence while diminishing the formation of intermediate products. As a result, NO is predominantly converted to nitrate (NO3−). This work unveils a novel approach to constructing semiconductor-cocatalyst heterostructures and elucidates their role in NO photooxidation.

Photooxidation Process of Aromatic Components of Petroleum by Sunlight

Photooxidation Process of Aromatic Components of Petroleum by Sunlight

Designing a NiFe-LDH/MnO2 heterojunction to improve the photocatalytic activity for NOx removal under visible light

2D/2D heterojunctions between ultrathin NiFe-CO3 layered double hydroxide (LDH) and varying amounts of birnessite (δ-MnO2) were prepared using an environmentally friendly and cost-effective self-assembly method. The prepared samples have proven to be efficient in their application, mitigating NOx emissions via a photooxidative process. The effective creation of 2D/2D NiFe–LDH/MnO2 heterojunctions has been verified through a variety of characterisation techniques, such as XRD, FT-IR, TGA, XFR, N2 adsorption–desorption isotherms, HRTEM and SEM images, EDX, and XPS. Photocatalytic measurements have indicated that the heterojunction formed between NiFe-LDH and MnO2 modifies its photoconductive behaviour, significantly enhancing the visible light photocatalytic performance of the partners. Finally, the optimal relationship between NiFe-LDH and MnO2 in the photocatalytic process was studied. It was found that a ratio of 10:1, respectively, exhibited superior properties compared to the other composites, highlighting the best performance in the degradation of NO under visible light and notable stability during the recycling process.

Molecular dynamics simulations of the interfacial behaviors and photo-oxidation of phytosterol under different emulsion oil content

Phytosterol, recognized for its health benefits, is predominantly extracted from plants and exhibits significantly reduced stability under varying light conditions. Their photooxidation is significantly influenced by emulsion interfaces. This study examined the mechanism of interface structure on phytosterol photooxidation with unparalleled molecular precision, utilizing molecular dynamics simulations and experimental procedures. Hydrogen bonding between the hydroxyl group at the C3 position of phytosterols and water molecules, coupled with van der Waals forces between the hydrophobic regions and the oil phase, induced phytosterol molecules to disperse toward the interface. The elevated polarity of the oil phase, specifically in tributyrin, facilitated the permeation of water molecules into the oil phase. This was achieved by diminishing the emulsion's interfacial tension, thereby fostering the development of more interface or micelles, and accelerating the photooxidation process of phytosterols. These simulations unraveled that the preponderance of phytosterol distribution is localized and oxidized at the oil-water interface.

Green Light-Triggered Photocatalytic Anticancer Activity of Terpyridine-Based Ru(II) Photocatalysts.

The relentless increase in drug resistance of platinum-based chemotherapeutics has opened the scope for other new cancer therapies with novel mechanisms of action (MoA). Recently, photocatalytic cancer therapy, an intrusive catalytic treatment, is receiving significant interest due to its multitargeting cell death mechanism with high selectivity. Here, we report the synthesis and characterization of three photoresponsive Ru(II) complexes, viz., [Ru(ph-tpy)(bpy)Cl]PF6 (Ru1), [Ru(ph-tpy)(phen)Cl]PF6 (Ru2), and [Ru(ph-tpy)(aip)Cl]PF6 (Ru3), where, ph-tpy = 4'-phenyl-2,2':6',2″-terpyridine, bpy = 2,2'-bipyridine, phen = 1,10-phenanthroline, and aip = 2-(anthracen-9-yl)-1H-imidazo[4,5-f][1,10] phenanthroline, showing photocatalytic anticancer activity. The X-ray crystal structures of Ru1 and Ru2 revealed a distorted octahedral geometry with a RuN5Cl core. The complexes showed an intense absorption band in the 440-600 nm range corresponding to the metal-to-ligand charge transfer (MLCT) that was further used to achieve the green light-induced photocatalytic anticancer effect. The mitochondria-targeting photostable complex Ru3 induced phototoxicity with IC50 and PI values of ca. 0.7 μM and 88, respectively, under white light irradiation and ca. 1.9 μM and 35 under green light irradiation against HeLa cells. The complexes (Ru1-Ru3) showed negligible dark cytotoxicity toward normal splenocytes (IC50s > 50 μM). The cell death mechanistic study revealed that Ru3 induced ROS-mediated apoptosis in HeLa cells via mitochondrial depolarization under white or green light exposure. Interestingly, Ru3 also acted as a highly potent catalyst for NADH photo-oxidation under green light. This NADH photo-oxidation process also contributed to the photocytotoxicity of the complexes. Overall, Ru3 presented multitargeting synergistic type I and type II photochemotherapeutic effects.

Treatment of polluted water with pesticides by photo-oxidation (Fenton photo)

In this study, advance photo oxidation (Fenton Photo) used to treat some pesticides. Three pesticides were used: spider pesticides (Pyridaben), herbicides (Atlantes), and insecticides (Acetop-20). The ferric sulphate (FeSo4.7H2O) used as oxidant agents, hydrogen peroxide as catalase and sunlight as a source of ultraviolet radiation, TOC and COD tests were used to measure organic matter the variables in treatment are time and pesticide concentration. Removable Effeciency (RE) % of COD are (31.6, 44.1, 46.4) and of TOC test are (63, 58.4, 43.5) at the treatment time (15, 30, 40) minute. According to the findings, treatment duration and pollutant concentration significantly impacted the effectiveness of the removal process.

Particulate/gaseous pollutants and solar radiation fluctuations over Bhubaneswar amidst two special events: Diwali and solar eclipse

This work presents short-term investigations to assess variations in PM2.5, PM10, SO2, NO2, O3, CO, BC, light NMHCs (ethane, ethylene, propane, propylene, and acetylene) and solar radiation at Bhubaneswar, during two special events in consecutive years: Diwali (2021 & 2022) and partial solar eclipse (2022). During 2022, PM levels were affected by meteorology and simultaneous occurrence of solar eclipse on the day after Diwali day (D-Day). Interesting atmospheric chemistry was observed due to emissions from crackers during Diwali night influencing solar flux on post-D-day, which in turn had an impact on the pollutant levels. NO2, SO2, CO, and O3 were below prescribed safety limits for both years, however, BC and NMHC concentrations were high on D-day due to contribution from crackers, biomass, and jute burning as a ritual in the state. Also, a sharp increase in CO and NO2 concentrations was noticed exactly during the most intense phase of eclipse due to cooling of atmosphere. The oxidant levels reduced as a result of sudden drop in the solar intensity during the event. In comparison to alkanes, the alkenes exhibited high O3-forming potential (97–98%) during both the years. However, in 2022 the photo-oxidation process of alkenes was affected due to reduced solar flux on D-day. Further O3 concentration on 2022 D-Day was comparatively lower (10%) than 2021 D-day with a reduction in surface O3 concentration (43.50%) almost 2 h after the eclipse. Thus, O3 chemistry during Diwali can be attributed to both natural phenomena and man-made activities.