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2022 ◽  
Vol 12 (1) ◽  
pp. 76
Author(s):  
Muhammad Tanveer ◽  
Gokce Tezcanli ◽  
Muhammad Tahseen Sadiq ◽  
Syeda Memoona Kazmi ◽  
Nawal Noshad ◽  
...  

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.


Polymers ◽  
2022 ◽  
Vol 14 (1) ◽  
pp. 217
Author(s):  
Ladislav Dzurenda ◽  
Michal Dudiak ◽  
Eva Výbohová

The wood of maple (Acer Pseudopatanus L.) was steamed with a saturated steam-air mixture at a temperature of t = 95 °C or saturated steam at t = 115 °C and t = 135 °C, in order to give a pale pink-brown, pale brown, and brown-red color. Subsequently, samples of unsteamed and steamed maple wood were irradiated with a UV lamp in a Xenotest Q-SUN Xe-3-H after drying, in order to test the color stability of steamed maple wood. The color change of the wood surface was evaluated by means of measured values on the coordinates of the color space CIE L* a* b*. The results show that the surface of unsteamed maple wood changes color markedly under the influence of UV radiation than the surface of steamed maple wood. The greater the darkening and browning color of the maple wood by steaming, the smaller the changes in the values at the coordinates L*, a*, b* of the steamed maple wood caused by UV radiation. The positive effect of steaming on UV resistance is evidenced by the decrease in the overall color difference ∆E*. While the value of the total color diffusion of unsteamed maple wood induced by UV radiation is ∆E* = 18.5, for maple wood steamed with a saturated steam-air mixture at temperature t = 95 °C the ∆E* decreases to 12.6, for steamed maple wood with saturated water steam with temperature t = 115 °C the ∆E* decreases to 10.4, and for saturated water steam with temperature t = 135 °C the ∆E* decreases to 7.2. Differential ATR-FTIR spectra declare the effect of UV radiation on unsteamed and steamed maple wood and confirm the higher color stability of steamed maple wood.


Author(s):  
Zhiquan Li ◽  
Congwei Luo ◽  
Fengxun Tan ◽  
Daoji Wu ◽  
Xuedong Zhai ◽  
...  

As an endocrine disruptor, bisphenol A (BPA) is a severe threat to human health. In this study, nitrate (NO3-) photolysis with a low-pressure UV lamp (LP-UV) was employed to degrade...


Author(s):  
Ashish Kumar ◽  
Arathy Varghese ◽  
Vijay Janyani

AbstractThis work presents the performance evaluation of Graphene/ZnO Schottky junctions grown on flexible indium tin oxide (ITO)-coated polyethylene terephthalate (PET) substrates. The fabricated structures include chemical vapour deposition grown graphene layer on ITO-coated PET substrates. Polymethyl methacrylate assisted transfer method has been employed for the successful transfer of graphene from Cu substrate to PET. The smaller D-band intensity (1350 cm−1) compared to G-band (1580 cm−1) indicates good quality of carbon lattice with less number of defects. High-quality ZnO has been deposited through RF sputtering. The deposited ZnO with grain size 50–95 nm exhibited dislocation densities of 1.31270 × 10–3 nm−2 and compressive nature with negative strain of − 1.43156 GPa. Further, the electrical and optical characterization of the devices has been done through device I–V characterization and UV detection analysis. The UV detection capability of the device has been carried out with the aid of a UV-lamp of 365 nm wavelength. The fabricated graphene/ZnO photodetector showed good response to UV illumination. The device performance analysis has been done through a comparison of the device responsivity and detectivity with the existing detectors. The detectivity and responsivity of the fabricated detectors were 7.106 × 109 mHz1/2 W−1 and 0.49 A W−1, respectively.


Author(s):  
Alexander Kaltashov ◽  
Prabu Karthick Parameshwar ◽  
Nicholas Lin ◽  
Christopher Moraes

Abstract Photolithography is an essential microfabrication process in which ultraviolet (UV) light is projected through a mask to selectively expose and pattern a light-sensitive photoresist. Conventional photolithography devices are based on a stationary UV lamp and require carefully-designed optics to ensure that a uniform exposure dose is provided across the substrate being patterned. Access to such systems is typically limited to certain labs with domain-specific expertise and sufficient resources. The emergence of LED-based UV technologies has provided improved access to the necessary light sources, but issues with uniformity and limited exposure sizes still remain. In this work, we explore the use of a moving light source (MOLIS) for large-area lithography applications, in which the light source path speed, elevation, and movement pattern can be used to smooth out any spatial variations in source light intensity profiles, and deliver a defined and uniform cumulative UV exposure dose to a photoresist-coated substrate. By repurposing a 3D printer and UV-LED flashlight, we constructed an inexpensive MOLIS platform, simulated and verified the parameters needed to produce a uniform UV dose exposure, and demonstrate this approach for SU-8 microfabrication of features with dimensions relevant to many areas in biomedical engineering. The ready accessibility and inexpensive nature of this approach may be of considerable value to small laboratories interested in occasional and low-throughput prototype microfabrication applications.


2021 ◽  
Vol 945 (1) ◽  
pp. 012017
Author(s):  
Chin Ying Hui ◽  
Sin Jin Chung ◽  
Lam Sze Mun

Abstract A facile co-precipitation method was employed to fabricate hierarchical ZnO structure and characterized by various analytical instruments. The images of ZnO from field-emission scanning electron microscopy exhibited spheroidal morphology which composed of numerous layers of nanosheets and formed a hierarchical structure. Energy dispersive X-ray spectrum validated the presence of Zn and O atoms and its purity. X-ray diffraction pattern of ZnO revealed the establishment of hexagonal wurtzite structure. Optical property analysis disclosed that the as-fabricated ZnO had strong absorbance of wavelength from 350-410 nm with an absorption band edge of 367 nm. In this paper, the photocatalytic activity of hierarchical ZnO structure was confirmed by degradation of endocrine disrupting chemical, namely dimethyl phthalate under UV lamp irradiation. The photodegradation of dimethyl phthalate in aqueous solution over as-fabricated ZnO reached 55.9% after 60 min irradiation. The photocatalytic degradation of DMP obeyed the pseudo first-order kinetic reaction with a rate constant of 0.0166 min−1.


Minerals ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 1345
Author(s):  
Giulia Ricci ◽  
Andrea Maurizio Monti ◽  
Renato Pagano ◽  
Marco Martini ◽  
Luisa Caneve ◽  
...  

Quartz from La Sassa (Tuscany, Italy) presents a unique luminescence related to intrinsic and extrinsic defects in the crystal lattice due to the growth mechanisms in hydrothermal conditions. The bright fluorescence under the UV lamp was apparent to collectors since the early 1970s, and it entered the literature as a reference case of yellow-luminescent quartz. Early reports present the history of the discovery, the geological context, and preliminary luminescence measurements of the quartz nodules, suggesting various activators as potentially responsible of the peculiar luminescence effects: uranyl groups (UO22+), rare earths (Tb3+, Eu3+, Dy3+, Sm3+, Ce3+) and polycyclic aromatic compounds (PAH). Here, we report a full investigation of the La Sassa material, by a multi-analytical approach encompassing cathodoluminescence optical microscopy (OM-CL), laser-induced fluorescence (LIF), wavelength resolved thermally stimulated luminescence (WR-TSL), trace elements analysis by mass spectrometry (ICP-MS) and Raman spectroscopy (RS). The results provide a significant step forward in the interpretation of the luminescence mechanisms: the main luminescent centres are identified as alkali-compensated (mainly Li+ and Na+, K+ and H+) aluminum [AlO4/M+]0 centres substituting for Si, where the recombination of a self-trapped exciton (STE) or an electron at a nonbridging oxygen hole centre (NBOHC) are active.


2021 ◽  
pp. 123-131
Author(s):  
Jayabharathi Jayapal ◽  
M. Thenmozhi

In the present study, the removal of m- cresol in an aqueous medium was studied by the photoelectrocatalytic (PEC) degradation by the TiO2 suspension on dip-coated stainless steel electrode under UV lamp of the wavelength of 352nm. The performance of the PEC method on the degradation of m- cresol was studied by made the comparison with the photocatalytic oxidation (PCO) method in terms of COD removal and kinetic study. In the PEC study on the degradation of m- cresol pollutant was studied by the various parameters such as initial concentration, pH, and the bias potential. The result found that the optimum degradation efficiency of m- cresol in the PEC and PCO methods were 79.6% and 39.8% at pH 5.0. The result showed that the kinetic constants (k) in the PEC and PCO methods were -0.0116 and -0.0058 under optimum conditions. The result found that the PEC method using TiO2 coated on stainless steel electrode is two times higher than the PCO method on the degradation of m- cresol.


2021 ◽  
Vol 13 (21) ◽  
pp. 11896
Author(s):  
Evie L. Papadopoulou ◽  
Giulia Biffi ◽  
Anitha Senthamizhan ◽  
Beatriz Martín-García ◽  
Riccardo Carzino ◽  
...  

A paper sensor was designed in order to detect the presence of nanomaterials, such as ZnO and silica nanoparticles, as well as graphene nanoplatelets (GnP), based on fluorescence changes of carbon nanodots. Paper strips were functionalized with carbon nanodots using polyvinyl alcohol (PVA) as binder. The carbon nanodots were highly fluorescent and, hence, rendered the (cellulosic) paper stripes emissive. In the presence of silica and ZnO nanoparticles, the fluorescence emission of the carbon nanodots was quenched and the emission decay was shortened, whereas in the presence of GnP only emission quenching occurred. These different photoluminescence (PL) quenching mechanisms, which are evident from lifetime measurements, convey selectivity to the sensor. The change in fluorescence of the carbon dot-functionalized paper is also evident to the naked eye under illumination with a UV lamp, which enables easy detection of the nanomaterials. The sensor was able to detect the nanomaterials upon direct contact, either by dipping it in their aqueous dispersions, or by sweeping it over their powders. The use of the proposed optical sensor permits the detection of nanomaterials in a straightforward manner, opening new ways for the development of optical sensors for practical applications.


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