Effect Of Irradiation Time Research Articles

An S-scheme TiO2/g-C3N4 nanocomposite effectively degrades phenanthrene under visible light

It is a challenge to effectively degrade phenanthrene (PHE) pollutants, which are widely present in aquatic environments, in order to reduce harm to humans and ecosystems. In this study, an S-scheme TiO2/g-C3N4 photocatalytic system is constructed using 0D TiO2 nanospheres and 2D g-C3N4 nanosheets for the removal of PHE from water under sunlight irradiation. The effects of irradiation time, quality ratio of TiO2 to g-C3N4, and cycle time on the performance of the TiO2/CN photocatalyst are investigated. The experimental results show that the ratio of TiO2 to g-C3N4 significantly affects the photocatalytic activity of the photocatalyst. Under the optimal ratio of TiO2 to g-C3N4 (50 % TiO2/CN), the apparent reaction rate constant for phenanthrene reached 0.00796 min−1, which is 11.5 times higher than that of pure TiO2 (0.00069 min−1). The tests of optical performance and photoelectrochemical properties further confirmed that the construction of the TiO2/g-C3N4 S-type photocatalyst successfully enhanced the spatial separation efficiency of photogenerated carriers and ensured a continuous supply of energy during the redox reaction process. Converting highly toxic phenanthrene into a non-toxic green degradation product provides an practical strategy for the safe treatment of PHE in aqueous environments through the use of visible-light-driven heterojunction photocatalysts. Additionally, the data collected on phenanthrene degradation in this study will provide valuable references for developing degradation methods for other PAHs, such as naphthalene, anthracene, and pyrene.

Bio-Mediated Synthesis of ZnO Nano Photocatalyst using C. gigantea (L.): Microstructural Study for Rapid Degradation of Organic Pollutants from Aqueous Medium

The purpose of this paper was to synthesize ZnO nanoparticles (NPs) from Calotropis gigantea (L.) and use them as photocatalyst for the elimination of wastewater contaminants, methyl orange (MO), and paracetamol (PCM) by UV irradiation. The UV-Vis absorption spectra show a peak at a wavelength of 374 nm with excitonic band gap of 3.41 eV. The hexagonal unit cell with mean crystallite size of 29.13 nm was found from the XRD pattern. The FESEM images confirms the formation of nanostructures. The bio-mediated nanoparticles are used as nano photocatalysts to eliminate MO and PCM. The effects of irradiation time, photocatalyst dose, dye concentration, and solution pH on photodegradation were studied in MO. Furthermore, the photodegradation of paracetamol was also investigated.

Effects of irradiation time on the structural, elastic, and optical properties of hexagonal (wurtzite) zinc oxide nanoparticle synthesised via microwave-assisted hydrothermal route

Effects of irradiation time on the structural, elastic, and optical properties of hexagonal (wurtzite) zinc oxide nanoparticle synthesised via microwave-assisted hydrothermal route

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.

Poly ortho-chloroaniline and poly ortho-chloroaniline titanium dioxide quantum dots for photo-degradation of organic hazardous materials

Conjugated polymers have recently been under active investigation as promising alternatives to use in photocatalysis. This is due to their unique advantages of low cost, high chemical stability, and molecularly tunable optoelectronic properties. This work explores the easy way to synthesize efficient poly ortho-chloroaniline (pO-CAN) via the chemical oxidative polymerization of O-CAN. Titanium dioxide quantum dots (TiQD) have been prepared and used in preparation of (pO-CAN)/TiQD. X ray diffraction, FTIR, UV &Visible spectra, TGA, surface area, EDX and TEM measurements were used to characterize all prepared polymers. The photocatalytic activities of all recent polymers were investigated by the photodegradation of methyl orang dye as an organic hazardous chemical in an aqueous medium was assessed using a 100-watt xenon lamp light source and direct sunlight for industrial wastewater samples. The effect of irradiation time on photodegradation performance of the dye in presence of recent polymers. (pO-CAN)/TiQD demonstrated high photocatalytic properties, with 79.9 % efficiency, as opposed to 48.8 % for (pO-CAN) only while it is 92.8 % for TiQD. When (pO-CAN), TiQD, and (pO-CAN)/TiQD are present during the recycling processes in the presence of all created samples up to six times, the photodegradation rate decreases by about 57.18, 9.61 and 9.51 % respectively. Also, the recycling and photodegradation performance of the industrial wastewater samples were evaluated and observed interested results.

Photostability Study of Avobenzone in Commercial Sunscreen SPF 45 with Additional SolaStay® Quencher Upon Sun Exposure

Avobenzone combined with various concentrations of Ethylhexyl Methoxycrylene (SolaStay® S1 quenchers) aims to see photostability studies. So that in this study tested the effect of SolaStay® S1 quenchers, SolaStay® quencher concentration, and the effect of irradiation time with sunlight on the photostability of avobenzone in commercial sunscreen formulations SPF 45. As well as determining the best SPF 45 commercial sunscreen formulations with the addition of Quenchers. The method used in this study is the spectroscopic method which uses two UV-VIS and HPLC spectrophotometer analyser. Based on the research data obtained in the presence of a quencher showed good photostability to avobenzone at certain quencher concentrations. Compared to F0, the effect of the addition of the quencher was very good, as seen from the relatively low decrease in the photodegradation rate compared to without the addition of the quencher. Viewed from the overall results, FSOL1 with the addition of 3% SolaStay® is the best SPF 45 sunscreen formulation of all formulations. This is seen from the small photodegradation results every time and the effect of skin effects was low. Keywords: Avobenzone, Quencher, Photostability, Photodegradation, SolaStay®, Sunscreen

Irradiation time dependent of the ZnO/GO composite formation on the photodegradation of Rhodamine B

Rhodamine B (Rh B) is one of the dyes used in the dyeing of paints, acrylic, and fabrics as well as biological products. A high concentration of Rh B is highly toxic and dangerous to living organisms when directly discharged into water. Therefore, in this study, the degradation of Rh B in water by zinc oxide/graphene oxide (ZnO/GO) composite was investigated. The zinc oxide (ZnO) was recovered from zinc ash, waste from galvanization industries, by acid leaching process using hydrochloric acid (HCl), while the graphene oxide (GO) was synthesized by modified Hummers method. The nanocomposite of ZnO/GO was synthesized using microwave irradiation and characterized by means of Field Emission Scanning Electron Microscope (FE-SEM), X-Ray Diffraction (XRD), and Fourier Transform Infrared (FTIR). The effect of irradiation time during ZnO/GO nanocomposite formation on the photocatalysis activity of the ZnO/GO in degrading Rhodamine B under UV rays was studied. The irradiation time was varied for 6, 8, and 10 minutes. The characterization results confirm that ZnO, GO, and ZnO/GO have been successfully synthesized. The ZnO/GO nanocomposite was also responsive to UV rays and able to degrade Rh B, as one of the examples of water pollutants. The highest degradation of Rhodamine B is achieved by the ZnO/GO nanocomposite prepared at 10 minutes of irradiation. The results of this study demonstrate that microwave irradiation time affects the ability of the nanocomposite to degrade Rhodamine B.

Effect of irradiation time by Light Emitting Diode on Water sorption of two different glass ionomer restoratives, in-vitro study

Effect of irradiation time by Light Emitting Diode on Water sorption of two different glass ionomer restoratives, in-vitro study

Auramine O UV Photocatalytic Degradation on TiO2 Nanoparticles in a Heterogeneous Aqueous Solution

Amongst the environmental issues throughout the world, organic synthetic dyes continue to be one of the most important subjects in wastewater remediation. In this paper, the photocatalytic degradation of the dimethylmethane fluorescent dye, Auramine O (AO), was investigated in a heterogeneous aqueous solution with 100 nm anatase TiO2 nanoparticles (NPs) under 365 nm light irradiation. The effect of irradiation time was systematically studied, and photolysis and adsorption of AO on TiO2 NPs were also evaluated using the same experimental conditions. The kinetics of AO photocatalytic degradation were pseudo-first order, according to the Langmuir–Hinshelwood model, with a rate constant of 0.048 ± 0.002 min−1. A maximum photocatalytic efficiency, as high as 96.2 ± 0.9%, was achieved from a colloidal mixture of 20 mL (17.78 μmol L−3) AO solution in the presence of 5 mg of TiO2 NPs. The efficiency of AO photocatalysis decreased nonlinearly with the initial concentration and catalyst dosage. Based on the effect of temperature, the activation energy of AO photocatalytic degradation was estimated to be 4.63 kJ mol−1. The effect of pH, additional scavengers, and H2O2 on the photocatalytic degradation of AO was assessed. No photocatalytic degradation products of AO were observed using UV–visible and Fourier transform infrared spectroscopy, confirming that the final products are volatile small molecules.

Effect of irradiation time on characteristics of Gd2O3:Er,Yb NPs by laser ablation in liquid

Effect of irradiation time on characteristics of Gd2O3:Er,Yb NPs by laser ablation in liquid

Effect of chemical desulfurization on coal properties and sulfur structure based on microwave technology

AbstractUnder the two frequency microwave conditions of 915 and 2450 MHz, orthogonal tests were designed to investigate the effects of organic acid reagent, microwave irradiation time, and mixing time of additives and coal samples on the desulfurization effect of coal. Results show that the effect of irradiation time on the experimental desulfurization efficiency under frequency microwave conditions is large and is the main factor. The desulfurization effect under 915 MHz microwave condition is better than 2450 MHz microwave condition. Two sets of experimental optimal coal samples were used for characterization and analysis. Thermogravimetric analysis revealed that the combustion temperature range of the coal samples is shortened and the integrated combustion index is considerably higher after the microwave irradiation experiment. Fourier‐transform infrared spectroscopy analysis showed that the overall chemical structure of the coal samples does not change significantly after the experimental treatment. X‐ray photoelectron spectroscopy analysis showed that the intensity of organic sulfur in coal samples is weakened after microwave irradiation, the characteristic peaks of thiols and thioethers are reduced to a great extent, and an increase in the intensity of sulfoxide organic sulfur is observed. On the basis of the results of experimental analysis and quantum chemical simulation calculations, the mechanism of organosulfur structure removal under the action of microwave is revealed.

Light-induced synthesis and characterization of “Clickable” polyacrylamide hydrogels

Hydrogels are important three-dimensional network polymers for various technologies ranging from tissue engineering to bio-sensing due to their high water absorption, biocompatibility and non-toxic characteristics. A desirable feature of hydrogels is to possess suitable functionalities for post modification that can support their extended applications. In the present work, we report a facile synthesis of clickable polyacrylamide hydrogel by photopolymerization using acrylamide and propargyl acrylate in the presence of different photoinitiators and in the absence of any additional conventional crosslinking agent under ultraviolet (UV) and visible light. The effect of irradiation time on gel fraction, swelling degree and compressive elasticity was investigated. Thiol-ene, thiol-yne and copper-catalyzed azide-alkyne cycloaddition click functionality of the produced hydrogels were confirmed by using respective fluorescent click components.

Assessment of ablation damage on quartz ceramics through experiment and 3D modelling considering a dynamic heat source

The effects of irradiation time (IT), laser power (LP), and spot diameter (SD) on the damage caused to quartz ceramics under continuous-wave laser irradiation were investigated through an orthogonal experiment. The experimental results show that the LP has the dominant effect on the depth of an ablation pit, while the SD has the greatest impact on the diameter of the ablation centre. The diameter and depth of the ablation pit were both positively correlated to the irradiation energy. The bubbles and molten silica transition layer affected the laser beam's reflection and transmission properties, leading to the incident laser beam scattering into the entire ablation pit and forming an elliptical ablation pit. Furthermore, a 3D finite element (FE) model considering a dynamic heat source was developed to simulate the laser damage process. The shape and dimension of the ablation pit predicted by the FE model were consistent with those obtained through the experiment, demonstrating the effectiveness and rationality of the model. The FE analysis results show that the different ablation rates in the radial and depth directions significantly influence the morphology of the ablation pits. The temperature gradient in the transition region increases while the thickness of the transition region decreases as the LP increases. This indicates that a large LP will lead to greater thermal stress in this area and result in more microcracks.

Photocatalytic degradation of Janus Green Blue dye in wastewater by green synthesised reduced graphene oxide-silver nanocomposite

ABSTRACT In this study, green synthesis of reduced graphene oxide-Ag (rGO-Ag) nanocomposite was carried out via bioreduction of Ag salt and graphene oxide (GO) using waste dry cell battery rod and Corchorus olitorius extract as GO precursor and reducing agent, respectively. Characterisation of rGO-Ag nanocomposite was achieved by UV/Vis spectroscopy, XRD, SEM, FTIR and BET analyses. Photocatalytic degradation of Janus Green blue (JGB) dye was conducted in batch mode. Effects of irradiation time, photocatalyst composition, temperature and recyclability were investigated. BET surface area of the nanocomposite was 532.914 m2/g with pore size of 2.136 nm. Optimal percentage photo-removal and equilibrium adsorption capacity of JGB dye by the nanocomposite achieved were 95.72% and 120.48 mg/g, respectively. Photocatalytic adsorption process followed more accurately Freundlich model implying multilayer adsorption onto rGO-Ag surface. Adsorption kinetics fitted perfectly into pseudo-second-order model while the enthalpy change is endothermic. The photocatalyst exhibited considerable stability, efficiency and was successfully applied for the removal of JGB in wastewater samples.

The Effects of Irradiation Time on Gelatin Methacrylate Hydrogels Used for Bone Tissue Engineering

Gelatin methacrylate (GelMA) hydrogels are a promising material for use in a variety of tissue engineering applications. Herein, we focused on identifying the optimal irradiation time necessary to photopolymerize GelMA hydrogels with visible blue light in a manner that did not adversely impact the biophysical properties of these cell-containing gels. We assessed the toxic effects of different irradiation times (3, 5, 10, 20 and 40 seconds) on BMMSCs encapsulated in a GelMA hydrogel using lithium phenyl-2,4,6 trimethylbenzoylphosphinate (LAP) as a photoinitiator. Both CCK-8 assays and Live-Dead staining were used to measure BMMSCs viability. We observed increasing compression strength as a function of increased irradiation time, although this corresponded to a reduction in swelling ratio and pore sizes. We ultimately found that when using LAP as a photoinitiator, the optimal irradiation time was 5–10 seconds, which was suitable for bone tissue engineering application. Ultimately we determined that a 5 second irradiation time was optimal for studies of encapsulated stem cells.

Using chemical agent in microwave assisted devulcanization of NR/SBR blends: An effective recycling method

The aim of this research was using a new chemical devulcanizing agent (i.e. VitaX) in devulcanization of NR/SBR blend as a model compound of tire rubber by microwave (MW) irradiation. For this purpose, the rubber compounds were prepared at different natural rubber (NR) to styrene butadiene rubber (SBR) ratios (40:60, 50:50, 60:40, 70:30 and 80:20). The rubbers were cured and then ground to particles with different mesh sizes (3, 4, 8, 16 and 30). The effect of irradiation time, stirring speed and particle size on sol/gel fractions, crosslink density (CLD) and devulcanization percent (DP) of the microwave irradiated samples was evaluated. Thereafter, effects of using VitaX and its content (0.3, 0.6, 1, 2, 3 and 4 phr) on devulcanized samples was evaluated. Results showed that using VitaX along with microwave irradiation caused decrease in the CLD and increase in the DP (from 9.51 to 34.85%) compared to the microwave assisted devulcanized samples. Finally, the raw NR/SBR rubber compound were replaced by different contents (10, 20 and 30 phr) of the chemical-microwave assisted devulcanized sample. The mechanical and curing properties of the samples were evaluated by tensile test and Oscillating Disk Rheometer (ODR), respectively. The results showed that at replacing content of 10 wt.%, decrement in the curing time and increment in the scorch time, cure rate index (CRI) and CLD was occurred in the re-vulcanized compound. The chemical-MW irradiation based devulcanization method was found to be a promising method for effective recycling of NR/SBR based rubbers such as tire rubbers.

Tin sulfide nanoparticles as photocatalysts for the degradation of organic dyes

Tin sulfide (SnS) nanoparticles were prepared from tin(II) dithiocarbamate single source precursors. Powder X-ray diffraction patterns of the SnS nanoparticles confirmed orthorhombic herzenbergite phase of tin sulfide. High-resolution transmission electron microscope images show spherically shaped tin sulfide with particles size in the range 1.0–2.8 nm. The bandgap energy obtained from Tauc plots is in the range 2.95–3.32 eV. The as-prepared SnS nanoparticles were used as nano photocatalysts for the degradation of brilliant green (BG), crystal violet (CV), methylene blue (MB) and methyl red (MR) under visible light irradiation. The degradation efficiency of BG by the SnS nanoparticles after 180 min irradiation are 76%, 81% and 70% by SnS-1, SnS-2 and SnS-3. Degradation efficiency of 66%, 90% and 75% were obtained for SnS-1, SnS-2 and SnS-3, respectively, against CV dye. While the efficiency of 79%, 97% and 93% were obtained for SnS-1, SnS-2 and SnS-3, respectively, against MB dye. The results showed that the as-prepared SnS nanoparticles are efficient photocatalyst for the degradation of BG, CV, MB and MR dyes. Liquid chromatography-mass spectrometry was used to investigate the degradation pathway of the organic dyes. The effects of irradiation time, scavengers and photostability on the photocatalysis process were also evaluated.

Irradiation Time of Photodynamic Therapy to the Number of Lactobacillus acidophilus

Lactobacillus acidophilus (L. acidophilus) is one of the etiological agents for dental caries and dominant in the deep carious lesion. L. acidophilus has also been identified in persistent root canal infection and also related to the failure of endodontic treatment. Photodynamic therapy is a therapeutic process involving the combination of a nontoxic photosensitizer and a light source. The excited photosensitizer reacts with reactive oxygen species (ROS), which induce injury and death of the microorganism. This study aimed to prove the effect of irradiation time of photodynamic therapy to the number of L. acidophilus. Fortytwo Eppendorf tubes were treated with 0.5 ml L. acidophilus distributed into seven groups. Group 1 as the control group received no treatment. Groups 2, 3, 4, 5, 6 and 7 were treated with a combination of 0.5 ml toluidine blue O (TBO) as a photosensitizer and 630 nm photoactivated (Fotosan®) exposure time for 10, 20, 30, 40, 50 and 60 sec. Then, all were stored in an incubator of 37ºC for 48 h. Later, the colony-forming unit (CFU) was counted for each group. There were significant differences in the number of L. acidophilus in CFU of the various irradiation times. The longer the photodynamic therapy irradiation was, the lesser the number of live L. acidophilus became. At 50 sec and 60 sec irradiation, none of the L. acidophilus was found alive.

Aggregation kinetics of UV-aged soot nanoparticles in wet environments: Effects of irradiation time and background solution chemistry

Soot nanoparticles (SNPs) undergo aging processes in aqueous systems, altering their physicochemical properties and affecting their fate and transport. This study investigated the aging effects via ultraviolet irradiation on aggregation kinetics of SNPs in water. The results showed that, compared to fresh SNPs, those irradiated for 1 day aggregated more easily in NaCl and CaCl2 solutions, with reduction of critical coagulation concentrations by 72% and 40%, respectively. Similar phenomena were found in additional six electrolyte solutions, and SNPs irradiated for > 3 days had no measurable difference in aggregation rate. The aggregation-enhancement of irradiated SNPs was more prominent at low electrolyte concentrations and pH > 4. However, in the presence of macromolecules, irradiated SNPs could be stabilized against aggregation via steric hindrance with strength of bovine serum albumin > humic acid > alginate > fulvic acid, whereas alginate further destabilized aged SNPs via calcium bridging. The fitted Hamaker constant increased from 7.8 × 10−20 (fresh) to 1.2 × 10−19 J (7-day irradiated), suggesting that decarboxylation during irradiation may weaken electrical repulsion and enhance van der Waals attraction, promoting aggregation. These results demonstrated the vital role of UV-induced aging in fate and transport of SNPs in wet environments.

Improvement of photocatalytic decomposition of methyl orange by modified MWCNTs, prediction of degradation rate using statistical models

Multi-walled carbon nanotubes (MWCNTs) have been successfully modified with TiO2 nanoparticles via a two-step hydrolysis technique. Firstly, the pristine MWCNTs are functionalized in nitric acid (HNO3) to creation of oxygen containing groups. Secondly, TiO2 nanoparticles are synthesized on the surface of functionalized MWCNTs through hydrolysis method. The synthesized samples have been used as photocatalyst for decomposition of methyl orange (MO) as dye organic pollutant. The characterization of samples using X-ray diffraction pattern (XRD) confirm the presence of TiO2 nanoparticles with mixture of anatase and rutile phases. Regarding the photocatalytic performance of TiO2 nanoparticles and modified MWCNTs with TiO2 nanoparticles, it observed that the degradation rate of MO increases by increasing the irradiation time from 5 to 35 min. The variation of degradation rate upon pH of suspension reveals that the maximum and minimum degradation rate are in acidic (pH = 3) and neutral condition (pH = 7). Meanwhile, the results show that the presence of MWCNTs leads to the enhancement of degradation rate. The analysis of variance (ANOVA) results confirm that both of main factors (irradiation time and pH) and their interaction have a significant influence on the degradation rate of MO. However, the effect of irradiation time is more than that of pH and their interaction. The graphical methods verify the quality and adequacy of the statistical models for prediction of the degradation rate.