Degradation of Diclofenac under Irradiation of UV Lamp and Solar Light Using ZnO Photo Catalyst

Diclofenac sodium (DCF) is a non-steroidal anti-inflammatory drug mainly used as an analgesic, arthritic and anti-rheumatic. This study deals with the degradation of diclofenac by photo catalytic-based advanced oxidation processes. Artificial UV lamp and solar rays have been applied to activate the ZnO catalyst, thereby generating highly oxidizing species. These species initiate the degradation process of the drug, which results in intermediates that finally dissociate into carbon dioxide and water. The solar reactor system is comprised of quartz and borosilicate tubes alternatively for the absorption and transmission of the solar rays to the pollutant sample. The degradation rate has been analyzed by composition analysis using high performance liquid chromatography. TOC and COD tests have also been conducted for degraded samples. ZnO catalyst loading was tested from 0.1 gm/L to 1 gm/L and the degradation rate showed a rising trend up to 0.250 gm/L, but further increase in loading resulted in a drop in degradation. Similarly, degradation is higher in acidic condition as compared to neutral or basic pH. The results showed a higher degradation rate for UV lamp irradiation as compared to the solar system. Moreover, TOC and COD reduction is also found to be higher for UV lamp photo catalysis.

Removal of Flotation Collector O-Isopropyl-N-ethylthionocarbamate from Wastewater

Flotation collector O-isopropyl N-ethylthionocarbamate (IPETC) is widely used for separation of sulfide ores. Its removal from water by several oxidation processes was studied. Photocatalytic oxidation with air in the presence of iron salts, utilizing solar irradiation or artificial UV-A light is very efficient. Oxidation leads through the formation of O-isopropyl N-ethylcarbamate and several other reaction intermediates to total decomposition of organic compound in the final stage in 1 day. Similar results were obtained with a Fenton type oxidation with hydrogen peroxide and iron salts. Treatment with sodium hypochlorite yields mainly O-isopropyl N-ethylcarbamate. The formation of this compound in wastewaters can be of concern, since simple alkyl carbamates are cancer suspect agents.

OXIDATIVE STRESS CAUSED BY UV RADIATION AND THE USE OF FTIR METHOD TO STUDY ITS EFFECT ON THE BIOLOGICAL TISSUES

Oxidative stress is caused by an imbalance between reactive oxygen species (ROS) generation and the capacity of antioxidant ROS scavenging systems and plays an essential role in the pathogenesis of many diseases. It is connected with cell damage, such as lipid peroxidation of membranes. One important source of oxidative stress is UV radiation, which can come from the natural environment or artificial sources like welding. While sources of artificial UV radiation emit specific wavelengths depending on the application, occupational exposure to natural UV radiation has a continuous spectrum from 290 nm to 400 nm. Oxidative stress can be measured by synchrotron radiation-based Fourier Transform Infrared (SR-FTIR) microspectroscopy. Oxidative effect of UV can be studied on human postoperative tissue. Here we show an in vitro study of the effect of UV C on the oxidative stress in human eye postoperative tissue.

Ag-TiO2 Nanocomposites: visible or solar light driven plasmonic photocatalysis?

Background: The demand for photocatalytic processes assisted by solar radiation has stimulated the upgrading of established systems, as the semiconductor modification with noble metals. Objective: the synthesis, characterization, and photocatalytic activity evaluation of the Ag-TiO2, against sulfamethoxazole molecule, and investigate the significance of the plasmonic phenomenon in Visible (450 - 1000nm) and UV-Vis (315-800 nm) radiation. Methods: Different nanocomposites Ag/TiO2 ratios were synthesized by the deposition of Ag nanoparticles on the TiO2 surface by in-situ photoreduction, and then calcinated at 400°C for 2 hr. The chemical-physical properties of the materials were examined by UV-Vis Diffuse Reflectance (UV-Vis DRS) Scanning Electronic Microscopy (SEM), Transmission Electronic Microscopy (TEM), X-Ray Energy Dispersive Spectroscopy (EDS). The experiments were conducted in a cooled photochemical reactor irradiated by halogen lamp (250W). The degradation of Sulfamethoxazole was monitored by HPLC-DAD. Results: Although the prepared photocatalysts show an intense plasmonic band centered at 500 nm, no photocatalytic activity was observed in the process assisted by artificial visible radiation ( ≥ 450 nm). In processes assisted by artificial UV-Vis radiation, the photolysis rate of the model compound (sulfamethoxazole) was higher than the photocatalytic rate, and in the absence of UV radiation, all the reactions were inhibited. The positive effect of the presence of silver nanoparticles onto the TiO2 surface was only evidenced in studies involving solar radiation. Conclusion: The results suggest the need for a balance between UV and Vis radiation to activate the nanocomposite and perform the sulfamethoxazole degradation.

PROTEOMIC SIGNATURES OF MICROBIAL ADAPTATION TO THE HIGHEST UV -IRRADIATION ON EARTH: LESSONS FROM A SOIL ACTINOBACTERIUM

In the Puna region, the total solar irradiation and the UV incidence is the highest on Earth, thus, restraining the physiology of individual microorganisms and the composition of microbial communities. UV-resistance of microbial strains thriving in High-Altitude Andean Lakes was demonstrated and their mechanisms were partially characterized by genomic analysis, biochemical and physiological assays. In this work, we present the molecular events involved in the adaptive response of the model HAAL extremophilic actinobacterium Nesterenkonia sp. Act20 under artificial UV-B radiation, herein called as UV-resistome. Proteomic profiles of cultures exposed to different UV-experimental conditions showed that the leading systems for adaptation to the UV-challenge in-vitro are DNA repair and antioxidant mechanisms.

Effect of Composite Composition in Nanofiber for Degradation of Humic Acid Solution

One of the basic needs for human is clean water. Many lowlands and marshy areas in larger islands in Indonesia such as Sumatra and Kalimantan are the source of peat water. This type of water is harmful for people living in such areas and it cannot be used directly for drinking and living. According to the standard quality of good water, peat water does not meet the requirements as a source of water for daily life. Peat water is acidic, red-brownish coloured, and it contains higher organic matters especially humic acid and its derivatives. Photocatalysis process is one of the promising way to treat solution that contains humic acid. This research aims to pre-eliminary study activity of PVDF-TiO2/ZnO nanofiber for degradation of humic acid solution. Photocatalytic activities were studied inside photoreactor system with artificial UV radiation with 254 nm wavelength. The percentage of degradation after contacting humic acid solution to photocatalyst was determined by measuring humic acid solution before and after degradation by using UV-Vis spectrophotometer with maximum lambda in 219 nm. The rate constants were calculated and the results were 0,03909 min-1 and 0.02832 min-1 respectively for PVDF-4%TiO2/ZnO and PVDF-8%TiO2/ZnOnanofibers and it is in pseudo first order kinetic model.

A detailed look at monoterpene oxidation reactions: results from the CERVOLAND field campaign and MCM modelling

<p>Atmospheric oxidation reactions can be studied in the field, in the lab and by modelling, with each methodic approach having advantages and issues. The main drawback for field experiments is that both chemical and non-chemical processes (emission, advection, vertical dilution, etc.) can simultaneously impact the chemical composition of ambient air, making it difficult to assess their respective contributions. For this purpose, a mobile atmospheric chamber (DouAir) has been developed to trap ambient air at a measurement site and to investigate the chemistry taking place in this isolated air mass. Since the environment within the chamber is controllable, oxidation processes can be measured and modelled with relative ease, so that the underlying chemistry can be better understood.</p><p>During July 2018 the DouAir chamber was brought to the Landes Forest in the southwest of France for the CERVOLAND field campaign (Characterisation of Emissions and Reactivity of Volatile Organic compounds in the LANDes forest). The reactor was used to trap real air masses coming from the surrounding forest - consisting mainly of Pinus pinaster trees - and the captured air was subsequently oxidised within the chamber. Different oxidation regimes were studied: dark oxidation, light oxidation by natural sunlight and light oxidation by artificial UV light with a known spectrum. Oxidation processes within the chamber were monitored by a variety of online instruments, including PTR-ToF-MS (for VOCs), PERCA (for peroxy radicals), O3 and NOx analysers, and CPC (for particles).</p><p>Here, we present the experimental results from the CERVOLAND field campaign under different oxidation conditions and the results from the 0-D modelling of these experiments using MCM. The focus is on measured and modelled monoterpene oxidation products and possible explanations for measurement-model discrepancies.</p>

Effect of silver doping on structural and photocatalytic circumstances of ZnO nanoparticles

This article describes the synthesis of ZnO nanoparticles (Nps) using the co-precipitation method and then calcinated at 500oC for 2 h. The photo activity of ZnO nanoparticles was examined in photo decolorization of methyl green dye under artificial UV -A light. This prepared photocatalyst (ZnO Np) was modified his surface by 2% Ag doped using the photo deposition method under inert gas for 3h. The characterization of undoped and 2% Ag doped ZnO Nps were estimated by Fourier-transform infrared spectroscopy (FT-IR), X-ray Diffraction (XRD), and Atomic force microscopy (AFM). In FT-IR analysis, the new peaks occurred around 624-778 cm-1 confirmed the Ag really is doped on prepared ZnO Np. Based on data from XRD, the mean crystal size was reduced with doped the 2% Ag. The AFM images for the prepared photocatalysts ensure that the shapes of all samples are semi-spherical with nanometer size. Series of kinetics experiments were performed for the photocatalytic decolourization of methyl green dye using undoped and 2% Ag doped ZnO nanoparticle and found to be pseudo-first-order kinetics.

Vasyl Holovach — Doctor of Biological Sciences, Professor (1924–1987)

Vasyl Holovach was doctor of biological sciences, professor. The main directions of scientific activity were elucidation of the etiology of chronic hematuria in cattle and research pertaining to the study of impact of artificial UV radiation sources on metabolism in the body of young cattle.