Presence Of Ultraviolet Radiation Research Articles

Kinetic study of adsorption and photocatalytic degradation of methylene blue dye using TiO2 nanoparticles with activated carbon

Activated carbon (AC) exhibits limited adsorption capacity for pollutants. Conversely, titanium dioxide (TiO2) demonstrates excellent photocatalytic performance, making it a popular choice for pollutant removal. This study investigates the removal of methylene blue (MB) dye from wastewater using AC, TiO2@AC-2, and TiO2@AC-10 samples via adsorption and photocatalysis. The Energy Dispersive analysis of x-rays (EDAX) has confirmed the presence of Ti, C and O in the prepared samples without any impurities. All the diffraction peaks in x-ray diffractograms indicated the presence of pure anatase TiO2 (tetragonal phase) with no evidence of any other phase. Fourier transform infrared spectroscopy (FTIR) analysis identified a peak around 545 cm−1 in the TiO2@AC-2 sample, indicative of O-Ti-O stretching vibrations. This peak shifted to 602 cm−1 in the TiO2@AC-10 sample. Raman spectroscopy confirmed the presence of carbon (D and G bands) at 1310–1347 cm−1 and 1582–1597 cm−1. Additionally, characteristic Raman active bands for anatase TiO2 were observed at 154 cm−1 (Eg), 204 cm−1 (Eg), 398 cm−1 (B1g), 508 cm−1 (A1g), and 628 cm−1 (Eg). N2 adsorption–desorption isotherms revealed a mesoporous structure for all samples (AC, TiO2@AC-2, and TiO2@AC-10) with hysteresis loops, indicating pores ranging from 2 nm to 50 nm in diameter. Reflectance spectra of TiO2@AC-2 and TiO2@AC-10 displayed absorption edges at 368 nm and 385 nm, respectively, corresponding to a direct band gap of approximately 3.22 eV. Subsequently, these prepared samples were effectively employed for the removal of methylene blue (MB) dye from wastewater utilizing both adsorption and photocatalysis method. Under dark conditions, 20 mg L−1 doses of TiO2@AC-2 and TiO2@AC-10 resulted in 60% and 36% dye adsorption within 60 min respectively. In the presence of UV radiation, the degradation of dye was observed to be 74% and 95% by TiO2@AC-2 and TiO2@AC-10 respectively. This observation indicates that TiO2 nanoparticles along with AC leads to enhanced photocatalytic activity. The Langmuir–Hinshelwood model reveals lower rate constants for AC compared to the composite samples. This is likely because AC lacks inherent catalytic activity, requiring UV light to trigger adsorption. Conversely, TiO2@AC-10 exhibits the highest rate constants (K1 = 24.25 × 10−3 min−1 and K2 = 82.71 × 10−3 min−1), aligning with its higher TiO2 content confirmed by EDAX analysis. This suggests a significantly faster photocatalytic rate and superior degradation efficiency, even at a low sample concentration (20 mg L−1).

Enhancing photocatalytic performance: Studying the synthesis and characterization of AgI-tuned TiO2/ZnO hybrid ternary nanocomposites

Eliminating phenol and other contaminants from wastewater is an essential step in addressing environmental issues. Using tailored photocatalysts is essential for the effective degradation of phenol via photocatalysis. The main objective of this study is to produce TiO2/ZnO/AgI nanocomposites employing the reflux approach in order to enhance the degradation of phenol in the presence of UV radiation. The nanocomposite incorporates TiO2 and ZnO, resulting in a narrowed band gap that enhances photocatalytic activity. The addition of AgI enhances electron transport capacities, resulting in an inclusive augmentation in performance. The physicochemical properties of the nanocomposite were extensively investigated applying an array of advanced techniques including as XRD, BET, FESEM, TEM, EDX and TGA spectroscopy practices. The combined effect of TiO2, ZnO, and AgI exhibits an approximately 100 % degradation of phenol, exceeding the individual performance of each component. The outcomes indicated that the operational parameters have a substantial impact on the photocatalytic activity, and the addition of H2O2 also improves degradation. The ideal conditions require a low concentration of H2O2 and a dose of 0.3 g/350 mL of nanocomposite. The reaction rate constant was reported as 6.96 × 10−3 min−1 under optimised conditions. The ternary nanocomposite exhibited recyclability for four successive cycles, eventually displaying ∼88 % degradation. The TiO2/ZnO/AgI nanocomposite system exhibits significant photocatalytic efficiency, which has important consequences for addressing environmental concerns caused by the persistent existence of various organic contaminants in water sources.

Evaluation of a hybrid advanced oxidation process for removal of pirimicarb insecticide in aqueous media: Statistical optimization and estimation of electrical energy consumption

AbstractIn this paper, the role of periodate and persulfate as inorganic oxidants were studied in presence of ultraviolet radiation and titanium dioxide nanoparticles as a hybrid advanced oxidation photocatalytic processes for degradation and mineralization of the pirimicarb insecticide in aqueous media. The effects of several factors such as the ultraviolet irradiation, initial oxidant concentration, titanium dioxide nanoparticles dosage, and pH on the process performance were investigated. The process optimization was performed by the central composite design as a tools of response surface methodology for 30 mg L−1 of the insecticide initial concentration at 25°C and 10 min of degradation process. A degradation efficiency of about 86% and 85% have been obtained for the persulfate and periodate processes, respectively, in the optimum conditions. The mineralization efficiency of the process using persulfate and periodate were about 35% and 46% after 60 min, respectively. The kinetic studies show that both processes follow a pseudo‐first‐order kinetic model and the rate constants were 0.1483 min−1 for the persulfate and 0.1152 min−1 for the periodate process. Generally, it can be concluded that this method is suitable for the degradation and mineralization of toxic aromatic compounds.

Ultraviolet Protection From a Patented Amino Acid Complex Technology.

  This study aimed to investigate the ultraviolet (UV) protection/repair benefits of a patented Amino Acid Complex (AAComplex). I) AAComplex was incubated with dermal fibroblasts, with/without UVA, and collagen I was measured with a GlasBoxPlus device. II) A lotion, with/without AAComplex (1%) was applied topically to skin explants, following UVA irradiation, and quantified for health-related biomarkers (TNFalpha, histamine, and MMP-1). III) A broad spectrum sunscreen with SPF 46 and a skincare serum containing AAComplex (2%) were assessed using epidermal equivalents, in the presence of UV irradiation, for effects on IL-1alpha, thymine dimers, Ki-67, filaggrin and Nrf2. I) Collagen I synthesis in dermal fibroblasts was significantly decreased after UVA compared to without UV. The presence of AAComplex prevented this decrease. II) UVA irradiation of skin explants increased histamine, TNFα, and MMP-1. Hydrocortisone aceponate cream significantly decreases all 3 biomarkers. AAComplex contained lotion also significantly decreased all 3 biomarkers, the no AAComplex control lotion only reduced histamine. III) With the regimen of sunscreen + AAComplex contained skincare serum, the significant reduction in IL-1alpha was observed along with a complete recovery of Ki-67 and stimulation of filaggrin and Nrf2T. No thymine dimer positive cell was observed indicating the most positive skin impact from the regiment.  Conclusion: This research using different human skin models demonstrated that AAComplex can provide protection and damage repair caused by UV, at the ingredient level also when formulated in a serum or lotion formula. Skin may be best protected from UV damage when the regimen is used.   J Drugs Dermatol. 2024;23(5):366-375. doi:10.36849/JDD.7916.

Solvothermal synthesis of Bi12TiO20/Bi4Ti3O12 heterostructure with highly efficient photodegradation of MO under UV irradiation

The sillenite-structured bismuth titanate (Bi12TiO20) is thought to be a viable photocatalyst for environmental remediation. However, the performance of Bi12TiO20 as a photocatalyst is severely constrained by its limited range of light sensitivity and the rapid photoinduced electron-hole pair recombination. A practical and effective way to overcome these limitations is to combine Bi12TiO20 with adequate photocatalysts to create heterojunctions. Here, a one-step solvothermal technique is used to synthesize Bi12TiO20/Bi4Ti3O12 heterojunction (BTO). The electric field that exists between B12TiO20, Bi4Ti3O12 and the closed interfacial contacts had a synergistic effect on the constructed composites, which resulted in high charge transfer abilities. Therefore, the BTO heterojunction demonstrated increased photocatalytic efficacy in the presence of ultraviolet irradiation. The MO removal efficiency of optimal BTO was 97.15%, significantly higher than that of pure Bi2O3 (46.9%). Furthermore, the cycling experiment demonstrated that the BTO heterojunction is stable and reusable. The probable mechanism of photocatalytic MO oxidation over BTO heterojunction was studied by various scavengers. The •OH radicals and holes played essential roles in BTO system of photocatalytic oxidation process.

UV-activated semiconductor gas sensor response measurement for formaldehyde detection

The gas sensing characteristics of ultraviolet light-emitting diodes (UV-LEDs)-activated semiconductor sensors were investigated to detect formaldehyde (HCHO) as a model volatile organic compound (VOC). As the major drawback of formaldehyde gas sensors is the low durability of the sensing material, efforts were made to establish a suitable metal oxide semiconductor and to enhance its stability throughout the sensing process. In2O3 nanoparticles (NPs) as the sensing material showed restructuring caused by exposure to different concentrations of formaldehyde in the presence of UV radiation when its morphology and structure were analyzed. UV radiation in the presence of formaldehyde was found to play a critical role in nanoparticles agglomeration, as well as its response inconsistency and instability.The novel method of measuring UV radiation elimination in the initial stages of the response curve was deemed effective for sensing layer preservation in this study. The scanning electron microscopy (SEM) results showed that this approach prevented any notable deformation in the nanoparticles’ shape and size and resulted in reproducible responses to various formaldehyde concentrations (10–50 ppm) in the steady-state and transient (5 min exposure) phases of the response curve. Hence, a short-time UV exposure has the potential to be applied in practical gas sensing applications in which the sensor can be automatically turned off a few minutes after any target gas detection. The gas sensor response slope in the transient phase of the response curve was found to be a very good indicator of target gas concentration and to obtain fast and consistent results while preserving the sensing material from restructuring. The findings of this study can be incorporated into the development of UV-LED-activated gas sensors where stable and fast response measurements of VOCs are required.

Fenton-like system of UV/Glucose-oxidase@Kaolin coupled with organic green rust: UV-enhanced enzyme activity and the mechanism of UV synergistic degradation of photosensitive pollutants

This study introduces the UV/glucose-oxidase@Kaolin (GOD@Kaolin) coupled organic green rust (OGR) system (UV/OGR/GOD@Kaolin) to investigate the promotion of glucose oxidase activity by UV light and its synergistic degradation mechanism for photosensitive pollutants, specifically targeting the efficient degradation of 4-chlorophenol (4-CP). The enzyme system demonstrates its ability to overcome drawbacks associated with traditional Fenton systems, including a narrow pH range and high localized concentration of H2O2, by gradually releasing hydrogen peroxide in situ within a neutral environment. In the presence of UV radiation under specific conditions, enhanced enzyme activity is observed, resulting in increased efficiency in pollutant removal. The gradual release of hydrogen peroxide plays a crucial role in preventing unwanted reactions among active substances. These unique features facilitate the generation of highly reactive species, such as Fe(IV)O, •OH, and •O2−, tailored to efficiently target the organic components of interest. Additionally, the system establishes a positive iron cycle, ensuring a sustained reactive capability throughout the degradation process. The results highlight the UV/OGR/GOD@Kaolin system as an effective and environmentally friendly approach for the degradation of 4-CP, and the resilience of the enzyme extends the system's applicability to a broader range of scenarios.

Development of CuO and CuO:Zn2+ nano-oxides for dye degradation and pharmaceutical studies

The effect of Zn2+ doping on photocatalytic and biomedical properties of CuO synthesized by the simple hydrothermal method was analyzed in this study. The phase structure, morphology, and surface chemistry of synthesized CuO and CuO:Zn2+ samples were analyzed. XRD analysis revealed the monoclinic phase of synthesized CuO. Due to the concentration of precursors and optimization of processing conditions, the morphology of CuO appears to be like pine needles. It is transformed from pine needles to blocks by incorporating Zn into the CuO matrix. In this study, CuO and CuO:Zn2+ photocatalysts were used for the degradation of Methylene Blue (MB) dye under UV light irradiation. The photocatalytic degradation process was studied under different conditions, including time-based study, pH, and catalyst concentration. Results showed that both CuO and CuO:Zn2+ photocatalysts were effective in degrading MB dye under UV light irradiation. The rate of dye degradation increased with increasing irradiation time. Moreover, the MTT approach was employed to evaluate the cell viability of MCF-7 cancer cells both in the absence and presence of UV radiation. The proportion of MCF-7 cells destroyed was elevated due to the easy diffusion of CuO and CuO:Zn2+ nano-oxides into cancer cells in anticancer activity without UV light. The anticancer activity under UV light was augmented, which was attributed to an increase in ROS generation caused by the increased dose of these CuO and CuO:Zn2+ compounds. As a result, these CuO and CuO:Zn2+ can potentially be used as drug delivery systems, and their low toxicity and therapeutic properties make them suitable for use as photosensitizers on MCF-7 cells when exposed to UV radiation.

Some features of trichlorobiphenyls photolysis

The photolytic decomposition of the Trikhlorbifenil mixture, 2,4,5- and 2,4,6-trichlorobiphenyls under an influence of ultraviolet radiation in presence of tungsten oxide as a catalyst in a methanol medium was studied. A higher rate of photolysis of individual congeners of polychlorbiphenyls was established compared to the congeners of the Trikhlorbifenil mixture. The influence of structural features of polychlorarenes on a depth of photodecomposition and a routes of formation of photodestruction products was considered.

Breaking down process barriers: ZnSe/CdSe composite catalysts drive enhanced catalytic properties and modified membrane structures for removing humic acid from aqueous environments

In the present research, with the aim of removing humic acid from wastewater, photo-catalytic membrane reactor was utilized. Single-component catalysts including ZnSe, CdSe, as well as composite catalyst (ZnSe/CdSe) were deposited in the surface layer of polysulfone membrane via photo-grafting method, whereby ZniCdjM11i and j are ZnSe and CdSe loading concentration level membranes were synthesized. The results indicated that the ZnSe/CdSe due to its shorter bandgap, had a more effective role in the grafting process and hence adjusting the membrane pore size. The pore size of Zn4Cd4M was smaller than that of Zn4Cd0M and Zn°Cd4M, and hence the humic acid separation in the dark mode by Zn4Cd4M was 80 %, which is about 10 % greater than the value obtained by Zn4Cd0M and Zn°Cd4M. The ZnSe/CdSe due to its less photoluminescence emission, proved to be more effective in photocatalytic reactions compared to the single component catalysts. The extent of photocatalytic degradation of humic acid in the presence of UV-radiation by the Zn°Cd4M, Zn4Cd0M, and Zn4Cd4M was reported 80, 84, and 96 % respectively. Overall, due to the smaller pore size, shorter bandgap, and lower recombination, TOC removal by the Zn4Cd4M (containing composite catalyst) was reported 98 %, while this value for the Zn4Cd0M and Zn°Cd4M was reported 60 and 66 % respectively.

Temperature profiles of field-aged photovoltaic modules affected by optical degradation

Moisture ingress into PV module in the presence of ultraviolet radiation, high temperature, and other environmental stressors can affect the optical integrity of the PV module. Optical degradation can take the form of delamination, discolouration of encapsulant, metal grids corrosion, and trapped moisture or chemical species. This can influence the photon absorption and current transport properties in the PV module bulk, which can affect the module operating temperature. In the present work, the relationship between optical degradation and temperature sensitivity of 20-year-old multicrystalline silicon field-aged PV modules have been investigated. The selected PV modules were characterized using visual inspection, current-voltage (I–V) characterization, temperature coefficients profiling, current resistivity profiling, infrared (IR) thermal, ultraviolet fluorescence (UV–F), and electroluminescence (EL) imaging. PV modules affected by optical degradation show weak fluorescence and luminescence signal intensities. The average difference in cell temperature (ΔT) between the warmest and coldest cell for the PV modules investigated was found to be around 10 ± 2 °C and the average power degradation rate was approximately 0.8% per year. The underlying factor for the observed degradation is attributed to the degradation in the temperature coefficients of open circuit voltage (βVoc) and maximum power point voltage (βVmpp). The average temperature coefficient of efficiency (βηm) of the modules was found to be around −0.5%/°C. Finally, a temperature dependent resistivity method for extracting temperature coefficients from IR thermal data of PV modules has been proposed.

Effect of thermal and ultraviolet exposure on volatile organic compounds emitted from basalt‐hemp reinforced polypropylene

AbstractIn recent years, the “new car smell” has been linked to materials off‐gassing toxic volatile organic compounds (VOCs) within the chamber of vehicles. Previous studies collected air samples directly from the vehicle chamber and analyzed them using gas chromatography–mass spectrometry (GC–MS). However, there is a lack of data regarding which materials are responsible for each compound and the resulting concentrations. This preliminary research was focused on analysis of VOC emissions emitted from basalt fiber and hemp hurd‐reinforced polypropylene (PP) panels, glass fiber reinforced PP panels, and PP panels intended for interior automotive applications such as dashboards and door panels. The panels were subjected to various temperatures and UV radiation that may be experienced within a vehicle. Results showed increasing concentrations as temperature increased, and a reduction in off‐gassing in the presence of UV radiation. The major compounds detected were acetaldehyde (<41 μg/m3), acetone (<29 μg/m3), and various alkanes (<6786 μg/m3). Overall, the concentrations detected from all panels were below the suggested standards and limitations.

Mesospheric Ozone Depletion Depending on Different Levels of Geomagnetic Disturbances and Seasons

Energetic electron precipitation (EEP) into the atmosphere are considered to play an important role in the natural forcing of the ozone variability and dynamics of the middle atmosphere during magnetospheric and geomagnetic disturbances. Energetic electrons from the radiation belt spill out into the atmosphere during geomagnetic disturbances and cause additional ionization rates in the polar middle atmosphere. These rates of induced atmospheric ionization lead to the formation of radicals in ion-molecular reactions at the heights of the mesosphere with the formation of reactive compounds of odd nitrogen groups NOy and odd hydrogen groups HOx. These compounds are involved in catalytic reactions that destroy ozone. The percentage of ozone destruction can depend not only intensity of EEP but also on season where it happens. In this work, we study mesospheric ozone depletion depending on seasons and precipitating energetic electrons with energies from keV up to relativistic energies about 1 MeV, based on the NOAA POES satellites observations in 2003. For estimation ozone deplation we use a one-dimensional radiative-convective model with ion chemistry. As one of the main results, we show that, despite the intensity of EEP-induced ionization rates, polar mesospheric ozone cannot be destroyed by EEP in summer in the presence of UV radiation. In winter time, the maximum ozone depletion, at altitude of about 80 km, can reach up to 80% during strong geomagnetic disturbances. In fall and spring, the maximum ozone depletion is less intense and can reach 20% during strong geomagnetic disturbances. Linear relation of EEP induced maximum mesospheric ozone depletion depending on geomagnetic disturbances and seasons have been obtained.

Exploring the influence of free radicals on photolytic removal of nadolol from water: Mechanism of degradation and toxicity of intermediates

β-blockers are known to have negative effects on fish and other aquatic animal species, so their removal is key for preserving aquatic ecosystems. To reduce the risks related to β-blockers, it is necessary to assess their effects and develop more effective treatments such as advanced oxidation processes. Improving sewage treatments is a critical approach to reducing β-blockers in aquatic environments. In this work, for the first time, the direct and indirect photolysis of nadolol (NAD) was investigated under different light sources (simulated solar (SS), UV-LED, and UV radiations) in ultrapure water. Indirect photolysis by H2O2 showed 1.5, 2.1, and 5.6 times higher NAD degradation efficiency than direct photolysis under mentioned irradiations. This effect was particularly pronounced in the presence of UV radiation, in which the degradation efficiency of NAD was the highest (80.2%). Computational analysis based on density functional theory calculations, together with the results of NAD photodegradation efficiency in the presence of radical scavengers (isopropanol and benzoquinone), was used to propose the NAD degradation mechanism. Sixteen degradation intermediates were proposed, along with their NMR chemical shifts. Also, this study analyzed the degree of catalase activity, lipid peroxidation, and hydroxyl radicals neutralization of NAD and its photodegradation mixtures obtained after indirect photolysis. The degree of mineralization and in vitro toxicity of NAD and its degradation intermediates obtained in the presence of UV/H2O2 were assessed.

Impact of ultraviolet radiation nearly overrides the effects of elevated pCO2 on a prominent nitrogen‐fixing cyanobacterium

AbstractAlthough the marine N2‐fixers Trichodesmium spp. are affected by increasing pCO2 and by ultraviolet radiation (UVR) in their habitats, little is known on their potential responses to future ocean acidification in the presence of UVR. We grew Trichodesmium at two pCO2 levels (410 and 1000 μatm) under natural sunlight, documented the filament length, growth, and chlorophyll content after its acclimation to the pCO2 treatments, and measured its carbon and N2 fixation rates under different solar radiation treatments with or without UVR. We showed that the elevated pCO2 did not significantly alter the diazotroph's growth, filament length, or pigment content, and its photosynthetic rate was only affected by solar radiation treatments rather than the pCO2 levels. The presence of UV‐A and UV‐B inhibited photosynthesis by 10–22% and 17–21%, respectively. Inhibition of N2 fixation by UV‐B was proportional to its intensity, whereas UV‐A stimulated N2 fixation at low, but inhibited it at high, intensities. Elevated pCO2 only stimulated N2 fixation under moderate levels of solar radiation. The simulated depth profile of N2 fixation in the water column showed that UV‐induced inhibition dominated the combined effects of elevated pCO2 and UVR at 0–30 m depth and the combination of these factors enhanced N2 fixation at 30–60 m depth, but this effect diminished in deeper water. Our results suggest that Trichodesmium could be influenced more by UVR than by pCO2 and their combined action result in negative effects on N2 fixation under high solar radiation, but positive effects under low to moderate solar radiation.

Investigations on effects of titanium dioxide (TiO2) nanoparticle in combination with UV radiation on breast and skin cancer cells.

In this study, we have investigated the chemotherapeutic potential of titanium dioxide (TiO2) nanoparticles on skin and breast cancer cells. The cells have treated with a 75µg/ml concentration of titanium dioxide because it is a recommended dose with proven effectiveness in vitro studies and then the cells were exposed to UV-A radiation. The combined effects of titanium dioxide and UV-A radiation on cell viability, cell cycle, plasma membrane, mitochondrial membrane potentials and apoptotic activity of the cells were investigated. The viability of SK-MEL 30 cells was measured by MTT assay and apoptotic activity of cells was determined by Annexin-V FITC/PI staining. As a result of the research, an increase was observed in the viability of cells treated with 75µg/ml titanium dioxide concentration, while a significant decrease in cell viability was observed for both cell types when UV-A radiation and TiO2 were applied together. The results also showed that the percentage of apoptotic cells increased as a result of UV + TiO2 exposure. Accordingly, it can be said that TiO2 nanoparticles may research as potential chemotherapeutic agents for skin and breast cancers, especially in the presence of UV radiation.

Ecological synthesis of nickel–zinc–aluminium layered double hydroxides (Ni–Zn–Al LDH) in flow infrared radiated agitated tubular reactor (flow-IR-ATR)

The yield of obtaining layered double hydroxides (LDHs) remains a significant challenge that limits their practical use on a large scale. The use of flow processes is an innovative approach to solving the problem. This paper describes a method for obtaining LDH nanoparticles using an agitated tube reactor heated by infrared radiation (flow-IR-ATR). As a dedicated reactor for production of LDH nanoparticles, it is able to synthesise products at a flow rate of 1.8 dm3/h and a yield of 40 g/h. In the process, LDH NPs based on zinc–aluminium hydroxides (Zn–Al LDH) and LDH NPs modified with nickel hydroxide (Ni–Zn–Al LDH), with molar ratio of Ni to Zn 0.5, were obtained. Instrumental analyses (XRD, FTIR, SEM, DLS, BET, XPS) were used to characterise the LDH nanoparticles obtained, which showed crystallite sizes from 9 to 35 nm. The nickel-containing LDHs exhibited high photocatalytic activity. After 60 min, in the presence of UV radiation (365 nm), the photodegradation efficiency of quinoline yellow (dye concentration of 100 mg/dm3) was more than 99.9%.Graphical

Effect of Poling on Photocatalysis, Piezocatalysis, and Photo-Piezo Catalysis Performance of BaBi4Ti4O15 Ceramics.

This study focuses on analyzing the poling effect of BaBi4Ti4O15 (BBT) on the basis of photo and piezo-catalysis performance. BBT powder is prepared via a solid state reaction followed by calcination at 950°C for 4 h. BBT is characterized by an X-ray diffractometer, scanning electron microscopy, Raman spectroscopy, and X-ray photoelectron spectroscopy. The optical bandgap of BBT is evaluated with the help of Tauc's plot and found to be 3.29eV, which comes in the photon energy range of ultra-violet radiation. BBT powder is poled by using Corona poling in the presence of 2kV mm-1 of electric field. An aqueous solution of methyl blue (MB) dye in the presence of UV radiation is used to evaluate the photo/piezocatalysis performance. Photocatalysis, piezocatalysis, and photo-piezo catalysis degradation efficiencies of poled and unpoled BBT powder are tested for 120 min of UV light irradiation. Photo-piezocatalysis shows degradation efficiencies of 62% and 40% for poled and unpoled BBT powder, respectively. Poling of BBT powder shows significant enhancement in degradation performance of MB dye in aqueous solution. Scavenger tests are also performed to identify reactive species.

Study of nonadibatic effect on dissociation channels of HCNH – the issue of abundance ratio [HNC]/[HCN] in upper atmosphere revisited

The abundance ratio [HNC]/[HCN] in upper atmosphere is known to vary depending on the various conditions, like the presence of UV radiation, the temperature of the region of abundance, etc. There have been attempts to justify the related observations from kinetic as well as thermodynamic considerations. In the present work we consider the dissociation of HCNH, right after its formation from electron capture of HCNH+, as the primary source of HNC and HCN in upper atmosphere. Few years back, from our group, a study of nonadiabatic effect on low-lying excited states of HCNH was undertaken to understand the formation of HNC. Present study is to explore the nonadiabatic effects on the various dissociation channels of HCNH leading to the formation of HCN and thus to justify the abundance ratio [HNC]/[HCN] in upper atmosphere. We present here the first ever exploration of the presence of conical intersection around the transition state geometries along the intrinsic reaction coordinate for the dissociation of HCNH into HCN and HNC.

Coral recruits are highly sensitive to heavy fuel oil exposure both in the presence and absence of UV light

Oil pollution remains a prominent local hazard to coral reefs, but the sensitivity of some coral life stages to oil exposure remains unstudied. Exposure to ultraviolet radiation (UVR), ubiquitous on coral reefs, may significantly increase oil toxicity towards these critical habitat-forming taxa. Here we present the first data on the sensitivity of two distinct post-settlement life stages of the model coral species Acropora millepora to a heavy fuel oil (HFO) water accommodated fraction (WAF) in the absence and presence of UVR. Assessment of lethal and sublethal endpoints indicates that both 1-week-old and 2-month-old recruits (1-wo and 2-mo) were negatively affected by chronic exposures to HFO (7 and 14 days, respectively). Relative growth (1-wo and 2-mo recruits) and survival (1-wo recruits) at end of exposure were the most sensitive endpoints in the absence of UVR, with no effect concentrations (NEC) of 34.3, 5.7 and 29.3 μg L-1 total aromatic hydrocarbons (TAH; ∑39 monocyclic- and polycyclic aromatic hydrocarbons), respectively. On average, UVR increased the negative effects by 10% for affected endpoints, and latent effects of exposure were evident for relative growth and symbiont uptake of recruits. Other sublethal endpoints, including maximum quantum yield and tissue colour score, were unaffected by chronic HFO exposure. A comparison of putative species-specific sensitivity constants for these ecologically relevant endpoints, indicates A. millepora recruits may be as sensitive as the most sensitive species currently included in oil toxicity databases. While the low intensity UVR only significantly increased the negative effects of the oil for one endpoint, the majority of endpoints showed trends towards increased toxicity in the presence of UVR. Therefore, the data presented here further support the standard incorporation of UVR in oil toxicity testing for tropical corals.