Search results for: degradation factors

Authors: Farida Kaouah, Chahida Oussalah, Wassila Hachi, Salim Boumaza, Mohamed Trari

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A catalyst of ZnO nanoparticles was used in the photocatalytic process of treatment for potential use towards bisphenol A (BPA) degradation in an aqueous solution. To achieve this study, the effect of parameters such as the catalyst dose, initial concentration of BPA and pH on the photocatalytic degradation of BPA was studied. The results reveal that the maximum degradation (more than 93%) of BPA occurred with ZnO catalyst in 120 min of stirring at natural pH (7.1) under solar light irradiation. It was found that chemical oxygen demand (COD) reduction takes place at a faster rate under solar light as compared to that of UV light. The kinetic studies were achieved and revealed that the photocatalytic degradation process obeyed a Langmuir–Hinshelwood model and followed a pseudo-first order rate expression. This work envisages the great potential that sunlight mediated photocatalysis has in the removal of bisphenol A from wastewater.

Keywords: bisphenol A, photocatalytic degradation, sunlight, zinc oxide, Langmuir–Hinshelwood model, chemical oxygen demand

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Authors: Mustafa Elfituri, Jonathan Cook

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Recently, graph-based computations have become more important in large-scale scientific computing as they can provide a methodology to model many types of relations between independent objects. They are being actively used in fields as varied as biology, social networks, cybersecurity, and computer networks. At the same time, graph problems have some properties such as irregularity and poor locality that make their performance different than regular applications performance. Therefore, parallelizing graph algorithms is a hard and challenging task. Initial evidence is that standard computer architectures do not perform very well on graph algorithms. Little is known exactly what causes this. The Graph500 benchmark is a representative application for parallel graph-based computations, which have highly irregular data access and are driven more by traversing connected data than by computation. In this paper, we present results from analyzing the performance of various example implementations of Graph500, including a shared memory (OpenMP) version, a distributed (MPI) version, and a hybrid version. We measured and analyzed all the factors that affect its performance in order to identify possible changes that would improve its performance. Results are discussed in relation to what factors contribute to performance degradation.

Keywords: graph computation, graph500 benchmark, parallel architectures, parallel programming, workload characterization.

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Authors: Mohamed Gar Alalm, Ahmed Tawfik

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In this study, photo-catalytic degradation of phenol by titanium dioxide (TiO2) in aqueous solution was evaluated. The UV energy of solar light was utilized by compound parabolic collectors (CPCs) technology. The effect of irradiation time, initial pH, and dosage of TiO2 were investigated. Aromatic intermediates (catechol, benzoquinone, and hydroquinone) were quantified during the reaction to study the pathways of the oxidation process. 94.5% degradation efficiency of phenol was achieved after 150 minutes of irradiation when the initial concentration was 100 mg/L. The dosage of TiO2 significantly affected the degradation efficiency of phenol. The observed optimum pH for the reaction was 5.2. Phenol photo-catalytic degradation fitted to the pseudo-first order kinetic according to Langmuir–Hinshelwood model.

Keywords: compound parabolic collectors, phenol, photo-catalytic, titanium dioxide

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Authors: Friday Godwin Okibe, Elaoyi David Paul, Oladayo Thomas Ojekunle

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In this study, Nitrogen and Phosphorous co-doped Zinc Oxide (NPZ) was prepared through a solvent-free reaction. The NPZ was characterized by Scanning Electron Microscopy (SEM) and Fourier Transform Infrared (FTIR) spectroscopy. The photocatalytic activity of the catalyst was investigated by monitoring the degradation of para-nitrophenol (PNP) under visible light irradiation and the process was optimized using factorial design of experiment. The factors investigated were initial concentration of para-nitrophenol, catalyst loading, pH and irradiation time. The characterization results revealed a successful doping of ZnO by nitrogen and phosphorus and an improvement in the surface morphology of the catalyst. The photo-catalyst exhibited improved photocatalytic activity under visible light by 73.8%. The statistical analysis of the optimization result showed that the model terms were significant at 95% confidence level. Interactions plots revealed that irradiation time was the most significant factor affecting the degradation process. The cube plots of the interactions of the variables showed that an optimum degradation efficiency of 66.9% was achieved at 10mg/L initial PNP concentration, 0.5g catalyst loading, pH 7 and 150 minutes irradiation time.

Keywords: nitrogen and phosphorous co-doped Zno, p-nitrophenol, photocatalytic degradation, optimization, factorial design of experimental

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Authors: Stephen V. Crowder, Jonathan W. Lane

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With short production development times, there is an increased need to demonstrate product reliability relatively quickly with minimal testing. In such cases there may be few if any observed failures. Thus it may be difficult to assess reliability using the traditional reliability test plans that measure only time (or cycles) to failure. For many components, degradation measures will contain important information about performance and reliability. These measures can be used to design a minimal test plan, in terms of number of units placed on test and duration of the test, necessary to demonstrate a reliability goal. In this work we present a case study involving an electronic component subject to degradation. The data, consisting of 42 degradation paths of cycles to failure, are first used to estimate a reliability function. Bootstrapping techniques are then used to perform power studies and develop a minimal reliability test plan for future production of this component.

Keywords: degradation measure, time to failure distribution, bootstrap, computational science

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Authors: Min-Hwa Lim, Mi-Jeong Park, Ho-Young Jung

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Imidazolium-brominated polyphenylene oxide (Im-bPPO) is based on the functionalization of bromomethylated poly(2,6-dimethyl-1,4-phenylene oxide) (BPPO) using 1-Methylimdazole. For the purpose of long cycle life of vanadium redox battery (VRB), the chemical stability of Im-bPPO, sPPO (sulfonated 2,6-dimethyl-1,4-phenylene oxide) and Fumatech membranes were evaluated firstly in the 0.1M vanadium (V) solution dissolved in 3M sulfuric acid (H2SO4) for 72h, and UV analyses of the degradation products proved that ether bond in PPO backbone was vulnerable to be attacked by vanadium (V) ion. It was found that the membranes had slightly weight loss after soaking in 2 ml distilled water included in STS pressure vessel for 1 day at 200◦C. ATR-FT-IR data indicated before and after the degradation of the membranes. Further evaluation on the degradation mechanism of the menbranes were carried out in Fenton’s reagent solution for 72 h at 50 ◦C and analyses of the membranes before and after degradation confirmed the weight loss of the membranes. The Fumatech membranes exhibited better performance than AEM and CEM, but Nafion 212 still suffers chemical degradation.

Keywords: vanadium redox flow battery, ion exchange membrane, permeability, degradation, chemical stability

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Authors: Farida Kaouah, Wassila Hachi, Lamia Brahmi, Chahida Ousselah, Salim Boumaza, Mohamed Trari

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The feasibility of using solar irradiation instead of UV light in photocatalysis is a promising approach for water treatment. In this study, photocatalytic degradation of a widely used textile dye, Acid Blue 25 (AB25), with noble metal loaded ZnO photocatalyst (Ag/ZnO), was investigated in aqueous suspension under solar light. The results showed that the deposition of Ag as a noble metal onto the ZnO surface, improved the photodegradation of AB25. . The effect of different parameters such as catalyst dose, initial dye concentration, and contact time was optimized and the optimal degradation of AB25 (97%) was achieved for initial AB25 concentration of 24 mg L−1 an catalyst dose of 1 g L−1 at natural pH (5.42) after 180 min. The kinetic studies were achieved and revealed that the photocatalytic degradation process obeyed to Langmuir–Hinshelwood model and followed a pseudo-first order rate expression. This work envisages the great potential that sunlight photocatalysis has in the degradation of dyes from wastewater

Keywords: acid dye, photocatalytic degradation, sunlight, zinc oxide, noble metal, Langmuir–Hinshelwood model

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Authors: O. P. Yadav

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Nano-size Ag-N co-doped ZnO/CuO composite photo-catalyst has been synthesized by chemical method and characterized using XRD, TEM, FTIR, AAS and UV-Vis spectroscopic techniques. Photo-catalytic activity of as-synthesized nanomaterial has been studied using degradation of methyl orange as a probe under UV as well as visible radiations. Ag-N co-doped ZnO/CuO composite showed higher photo-catalytic activity than Ag- or N-doped ZnO and undoped ZnO-CuO composite photo-catalysts. The observed highest activity of Ag-N co-doped ZnO-CuO among the studied photo-catalysts is attributed to the cumulative effects of lowering of band-gap energy and decrease of recombination rate of photo-generated electrons and holes owing to doped N and Ag, respectively. Effects of photo-catalyst load, pH and substrate initial concentration on degradation of methyl orange have also been studied. Photo-catalytic degradation of methyl orange follows pseudo first order kinetics.

Keywords: degradation, nanocomposite, photocatalyst, spectroscopy, XRD

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Authors: Jaroslav Fiala, Jaroslav Kaiser, Pavel Zlabek, Vaclav Mentl

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The X-ray diffraction technique was recognized as a useful tool for the assessment of material degradation degree after a long-time service. In many industrial applications materials are subjected to degradation of mechanical properties as a result of real service conditions. The assessment of the remnant lifetime of components and structures is commonly based on correlated procedures including numerous destructive, non-destructive and mathematical techniques that should guarantee reasonable precise assessment of the current damage extent of materials in question and the remnant lifetime assessment. This paper summarizes results of an experimental programme concentrated on mechanical properties degradation of welded components. Steel an Al-alloy test specimens of base metal, containing welds and simple weldments were fatigue loaded at room temperature to obtain Woehler S-N curve. X-ray diffraction technique was applied to assess the degradation degree of material as a result of cyclic loading.

Keywords: fatigue loading, material degradation, steels, AL-alloys, X-ray diffraction

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Authors: Bayan Alqassem, Israa A. Othman, Mohammed Abu Haija, Fawzi Banat

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The treatment of wastewater from highly toxic pollutants is one of the most challenging issues for humanity. In this study, the advanced oxidation process (AOP) was employed to study the catalytic degradation of phenol using different ferrite catalysts which are CoFe₂O₄, CrFe₂O₄, CuFe₂O₄, MgFe₂O₄, MnFe₂O₄, NiFe₂O₄ and ZnFe₂O₄. The ferrite catalysts were prepared via sol-gel and co-precipitation methods. Different ferrite composites were also prepared either by varying the metal ratios or incorporating chemically reduced graphene oxide in the ferrite cluster. The effect of phosphoric acid treatment on the copper ferrite activity. All of the prepared catalysts were characterized using infrared spectroscopy (IR), X-ray diffraction (XRD) and scanning electron microscopy (SEM). The ferrites catalytic activities were tested towards phenol degradation using high performance liquid chromatography (HPLC). The experimental results showed that ferrites prepared through sol-gel route were more active than those of the co-precipitation method towards phenol degradation. In both cases, CuFe₂O₄ exhibited the highest degradation of phenol compared to the other ferrites. The photocatalytic properties of the ferrites were also investigated.

Keywords: ferrite catalyst, ferrite composites, phenol degradation, photocatalysis

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Authors: Ivandic Kreso, Spiranec Miljenko, Kavur Boris, Strelec Stjepan

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This article discusses the possibility of using dilatometer tests (DMT) together with in situ seismic tests (MASW) in order to get the shape of G-g degradation curve in cohesive soils (clay, silty clay, silt, clayey silt and sandy silt). MASW test provides the small soil stiffness (G_o from v_s) at very small strains and DMT provides the stiffness of the soil at ‘work strains’ (M_DMT). At different test locations, dilatometer shear stiffness of the soil has been determined by the theory of elasticity. Dilatometer shear stiffness has been compared with the theoretical G-g degradation curve in order to determine the typical range of shear deformation for different types of cohesive soil. The analysis also includes factors that influence the shape of the degradation curve (G-g) and dilatometer modulus (M_DMT), such as the overconsolidation ratio (OCR), plasticity index (IP) and the vertical effective stress in the soil (s_vo'). Parametric study in this article defines the range of shear strain g_DMT and G_DMT/G_o relation depending on the classification of a cohesive soil (clay, silty clay, clayey silt, silt and sandy silt), function of density (loose, medium dense and dense) and the stiffness of the soil (soft, medium hard and hard). The article illustrates the potential of using MASW and DMT to obtain G-g degradation curve in cohesive soils.

Keywords: dilatometer testing, MASW testing, shear wave, soil stiffness, stiffness reduction, shear strain

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Authors: Charles Amoatey

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The issue of risk in the mining industry is a global phenomenon and the Ghanaian mining industry is not exempted. The main purpose of this study is to identify the critical risk factors affecting the mining industry. The study takes an integrated view of the mining industry by examining the contribution of various risk factors to mining project failure in Ghana. A questionnaire survey was conducted to solicit the critical risk factors from key mining practitioners. About 80 respondents from 11 mining firms participated in the survey. The study identified 22 risk factors contributing to mining project failure in Ghana. The five most critical risk factors based on both probability of occurrence and impact were: (1) unstable commodity prices, (2) inflation/exchange rate, (3) land degradation, (4) high cost of living and (5) government bureaucracy for obtaining licenses. Furthermore, the study found that risk assessment in the mining sector has a direct link with mining project sustainability. Mitigation measures for addressing the identified risk factors were discussed. The key findings emphasize the need for a comprehensive risk management culture in the entire mining industry.

Keywords: risk, assessment, mining, Ghana

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Authors: H. Boucheloukh, S. Rouissa, N. Aoun, M. Beloucifa, T. Sehili, F. Parrino, V. Loddo

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To optimize water purification and wastewater treatment by heterogeneous photocatalysis, we used NiFe₂O₄ as a catalyst and solar irradiation as a source of energy. In this concept, an organic substance present in many industrial effluents was chosen: naproxen ((S)-6-methoxy-α-methyl-2-naphthaleneacetic acid or 2-(6-methoxynaphthalenyl) propanoic), a non-steroidal anti-inflammatory drug. The main objective of this study is to degrade naproxen by an iron and nickel catalyst, the degradation of this organic pollutant by nickel ferrite has been studied in a heterogeneous aqueous medium, with the study of the various factors influencing photocatalysis such as the concentration of matter and the acidity of the medium. The photocatalytic activity was followed by HPLC-UV andUV-Vis spectroscopy. A first-order kinetic model appropriately fitted the experimental data. The degradation of naproxen was also studied in the presence of H₂O₂ as well as in an aqueous solution. The new hetero-system NiFe₂O₄/oxalic acid is also discussed. The fastest naproxen degradation was obtained with NiFe₂O₄/H₂O₂. In a first-place, we detailed the characteristics of the material NiFe₂O₄, which was synthesized by the sol-gel methods, using various analytical techniques: visible UV spectrophotometry, X-ray diffraction, FTIR, cyclic voltammetry, luminescent discharge optical emission spectroscopy.

Keywords: naproxen, nickelate, photocatalysis, oxalic acid

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Authors: Kittichai Thanasupsin, Satis Sukniam

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Pavement marking is an essential task of road construction and maintenance. One of several benefits of pavement markings has been used to provide information about road alignment and road conditions ahead. In some cases, retro-reflectivity of road marking at night may not meet the standard. This degradation may be caused by internal factors such as the size of glass beads and the number of glass beads or external factors such as traffic volume, lane width, vehicle weight, and so on. This research aims to investigate the reflective efficiency of thermoplastic road marking with the glass beads. Ratios of glass beads, ranging from 359 to 553 grams per square meter on an asphaltic concrete, have been tested. The reflective efficiency data was collected at the beginning and at a specific time interval for a total of 8 months. It was found that the difference in glass beads quantity affects the rate of retro-reflectivity but does not affect the diffuse reflectivity. It was also found that other factors affect retro-reflectivity, such as duration, the position of road marking, traffic density, the quantity of glass beads, and dirt coating on top. The dirt coating on top is the most crucial factor that deteriorating retro-reflectivity.

Keywords: thermoplastic pavement marking, retro-reflectivity, diffuse reflectivity, asphalt concrete

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Authors: Bharatendra Rai

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Cutting tools are widely used in manufacturing processes and drilling is the most commonly used machining process. Although drill-bits used in drilling may not be expensive, their breakage can cause damage to expensive work piece being drilled and at the same time has major impact on productivity. Predicting drill-bit breakage, therefore, is important in reducing cost and improving productivity. This study uses twenty features extracted from two degradation signals viz., thrust force and torque. The methodology used involves developing and comparing decision tree, random forest, and multinomial logistic regression models for classifying and predicting drill-bit breakage using degradation signals.

Keywords: degradation signal, drill-bit breakage, random forest, multinomial logistic regression

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Authors: Akshita Gaba, Ria P. Dey, Sanya Karotiya, Smrijanee Dash, Soni Gupta

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This research paper explores the significance of environmental awareness and community outreach initiatives undertaken by the Speak Up World Foundation; a non-profit organization founded in 2021. The study delves into the historical context of environmental issues, identifies the driving factors contributing to environmental degradation, and outlines tasks undertaken by the foundation to promote environmental consciousness. The paper also highlights the impact of these efforts on the community and emphasizes the need for continued dedication to ensure sustainable coexistence with our environment.

Keywords: environment, social service, organization, degradation, survey

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Authors: Mafel Obhuo, Dodeye I. Igbong, Duabari S. Aziaka, Pericles Pilidis

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An important feature of the exploitation of associated gas as fuel for gas turbine engines is a declining supply. So when exploiting this resource, the divestment of prime movers is very important as the fuel supply diminishes with time. This paper explores the influence of engine degradation on the timing of divestments. Hypothetical but realistic gas turbine engines were modelled with Turbomatch, the Cranfield University gas turbine performance simulation tool. The results were deployed in three degradation scenarios within the TERA (Techno-economic and environmental risk analysis) framework to develop economic models. An optimisation with Genetic Algorithms was carried out to maximize the economic benefit. The results show that degradation will have a significant impact. It will delay the divestment of power plants, while they are running less efficiently. Over a 20 year investment, a decrease of $0.11bn, $0.26bn and $0.45bn (billion US dollars) were observed for the three degradation scenarios as against the clean case.

Keywords: economic return, flared associated gas, net present value, optimization

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Authors: Ilma Robo, Saimir Heta, Edona Hasanaj, Vera Ostreni

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The hybrid layer, the way it is created and how it is protected against degradation over time, is the key to the clinical success of a composite restoration. The composite supports the dentinal structure exactly with the realized surface of microretension. Thus, this surface is in direct proportion to its size versus the duration of clinical use of composite dental restoration. Micro-retention occurs between dentin or acidified enamel and adhesive resin extensions versus pre-prepared spaces, such as hollow dentinal tubules. The way the adhesive resin binds to the acidified dentinal structure depends on the physical or chemical factors of this interrelationship between two structures with very different characteristics. During the acidification process, a precursor to the placement of the adhesive resin layer, activation of metaloproteinases of dental origin occurs, enzymes which are responsible for the degradation of the hybrid layer. These enzymes have expressed activity depending on the presence of Zn2 + or Ca2 + ions. There are several ways to inhibit these enzymes, and consequently, there are several ways to inhibit the degradation process of the hybrid layer. The study aims to evaluate chlorhexidine as a solution element, inhibitor of dentin activated metalloproteinases, as a result of the application of acidification. This study aims to look at this solution in advantage or contraindication theories, already published in the literature.

Keywords: hybrid layer, chlorhexidine, degradation, application

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Authors: Ritesh K. Shukla

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Degradation of biological samples in terms of macromolecules (DNA, RNA, and protein) are the major challenges in the forensic investigation which misleads the result interpretation. Currently, there are no precise methods available to circumvent this problem. Therefore, at the preliminary level, some methods are urgently needed to solve this issue. In this order, Comet assay is one of the most versatile, rapid and sensitive molecular biology technique to assess the DNA degradation. This technique helps to assess DNA degradation even at very low amount of sample. Moreover, the expedient part of this method does not require any additional process of DNA extraction and isolation during DNA degradation assessment. Samples directly embedded on agarose pre-coated microscopic slide and electrophoresis perform on the same slide after lysis step. After electrophoresis microscopic slide stained by DNA binding dye and observed under fluorescent microscope equipped with Komet software. With the help of this technique extent of DNA degradation can be assessed which can help to screen the sample before DNA fingerprinting, whether it is appropriate for DNA analysis or not. This technique not only helps to assess degradation of DNA but many other challenges in forensic investigation such as time since deposition estimation of biological fluids, repair of genetic material from degraded biological sample and early time since death estimation could also be resolved. With the help of this study, an attempt was made to explore the application of well-known molecular biology technique that is Comet assay in the field of forensic science. This assay will open avenue in the field of forensic research and development.

Keywords: comet assay, DNA degradation, forensic, molecular biology

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Authors: Ankur Bansal, Shashank Bishnoi

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Degradation of Sewage pipes, sewage pumping station and Sewage treatment plants(STP) is of major concern due to difficulty in their maintenance and the high cost of replacement. Most of these systems undergo degradation due to Biogenic sulphuric acid (BSA) attack. Since most of Waste water treatment system are underground, detection of this deterioration remains hidden. This paper presents a literature review, outlining the mechanism of this attack focusing on critical parameters of BSA attack, along with available models and software to predict the deterioration due to this attack. This paper critically examines the various steps and equation in various Models of BSA degradation, detail on assumptions and working of different softwares are also highlighted in this paper. The paper also focuses on the service life design technique available through various codes and method to integrate the servile life design with BSA degradation on concrete. In the end, various methods enhancing the resistance of concrete against Biogenic sulphuric acid attack are highlighted. It may be concluded that the effective modelling for degradation phenomena may bring positive economical and environmental impacts. With current computing capabilities integrated degradation models combining the various durability aspects can bring positive change for sustainable society.

Keywords: concrete degradation, modelling, service life, sulphuric acid attack

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Authors: M. Mahdavi, M. Mohseni, R. Rafiei, H. Yari

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Environmental factors can deteriorate the automotive coatings significantly. Such as UV radiations, humidity, hot-cold shock and destructive chemical compounds. Furthermore, some natural materials such as bird droppings and tree gums have the potential to degrade the coatings as well. The present work aims to study the mechanism of degradation for two automotive refinish coating (PU based) systems exposed to two types of biological materials, i.e. Arabic gum and the simulated bird dropping, pancreatin. To reach this goal, effects of these biological materials on surface properties and appearance were studied using different techniques including digital camera, FT-IR spectroscopy, optical microscopy, and gloss measurements. In addition, the thermo-mechanical behavior of coatings was examined by DMTA. It was found that cross-linking had a crucial role on the biological resistance of clear coat. The higher cross-linking enhanced biological resistance.

Keywords: refinish clear coat, pancreatin, Arabic gum, cross-linking, biological degradation

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Authors: Vishwas Chakranarayan, Mariyam Al Salman

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Despite the global environmental threats, previous approaches used to overcome these problems have failed to prevent environmental degradation. Scholars believe that entrepreneurs can help conserve habitats, combat climate change, increase freshwater availability, sustain biodiversity, and reduce environmental degradation and deforestation. The pandemic is creating a different ecosystem for fostering the eco-entrepreneurship opportunities. However, attending a course physically is a challenge for many willing learners. Therefore, it is an opportune time to contemplate on developing a social entrepreneurship curriculum which can be offered online.

Keywords: ecopreneurship, environmental problems, environmental degradation, entrepreneurship education

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Authors: M. S. Abd El-Sadek, Mahmoud A. Omar, Gharib M. Taha

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Photodegradation of methylene blue in the presence of tin dioxide (SnO₂) nanoparticles under solar light irradiation are known to be an effective photocatalytic process. In this study, pure and silver (Ag) doped tin dioxide (SnO₂) nanoparticles were prepared at calcination temperature (800ºC) by a modified sol-gel method and studied for their photocatalytic activity with methylene blue as a test contaminant. The characterization of undoped and doped SnO₂ photocatalyst was studied by X-rays diffraction patterns (XRD), transmission electron microscopy (TEM), Fourier Transform Infrared Spectroscopy (FT-IR) and Energy Dispersive X-ray Microanalysis (EDX). The catalytic degradation of methylene blue in aqueous media was studied using UV-Vis spectrophotometer to monitor the degradation process by measuring its absorption spectra. The main absorption peak of methylene blue is observed at λ= 664 nm. The change in the percent of silver in the catalyst affects the photoactivity of SnO₂ on the degradation of methylene blue. The photoactivity of pure SnO₂ was found to be a maximum at dose 0.2 gm of the catalyst with 100 ml of 5 ppm methylene blue in the water. Within 210 min of photodegradation (under sunlight) after leaving the reaction for 90 minutes in the dark to avoid the effect of adsorption, the pure SnO₂ at calcination temperature 800ºC exhibited the best photocatalytic degradation with removal percentage of 93.66% on methylene blue degradation under solar light.

Keywords: SnO₂ nanoparticles, methylene blue degradation, photocatalysis, silver doped-SnO₂

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Authors: Bekan Bogale, Tsegaye Girma Asere, Tilahun Yai, Fekadu Melak

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Aims: To study photocatalytic degradation of methylene blue dye on cuprous oxide/graphene nanocomposite. Background: Cuprous oxide (Cu2O) nanoparticles are among the metal oxides that demonstrated photocatalytic activity. However, the stability of Cu2O nanoparticles due to the fast recombination rate of electron/hole pairs remains a significant challenge in their photocatalytic applications. This, in turn, leads to mismatching of the effective bandgap separation, tending to reduce the photocatalytic activity of the desired organic waste (MB). To overcome these limitations, graphene has been combined with cuprous oxides, resulting in cuprous oxide/graphene nanocomposite as a promising photocatalyst. Objective: In this study, Cu2O/graphene nanocomposite was synthesized and evaluated for its photocatalytic performance of methylene blue (MB) dye degradation. Method: Cu2O/graphene nanocomposites were synthesized from graphite powder and copper nitrate using the facile sol-gel method. Batch experiments have been conducted to assess the applications of the nanocomposites for MB degradation. Parameters such as contact time, catalyst dosage, and pH of the solution were optimized for maximum MB degradation. The prepared nanocomposites were characterized by using UV-Vis, FTIR, XRD, and SEM. The photocatalytic performance of Cu2O/graphene nanocomposites was compared against Cu2O nanoparticles for cationic MB dye degradation. Results: Cu2O/graphene nanocomposite exhibits higher photocatalytic activity for MB degradation (with a degradation efficiency of 94%) than pure Cu2O nanoparticles (67%). This has been accomplished after 180 min of irradiation under visible light. The kinetics of MB degradation by Cu2O/graphene composites can be demonstrated by the second-order kinetic model. The synthesized nanocomposite can be used for more than three cycles of photocatalytic MB degradation. Conclusion: This work indicated new insights into Cu2O/graphene nanocomposite as high-performance in photocatalysis to degrade MB, playing a great role in environmental protection in relation to MB dye.

Keywords: methylene blue, photocatalysis, cuprous oxide, graphene nanocomposite

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Authors: Hamed Bazrafshan, Saeideh Dabirnia, Zahra Alipour Tesieh, Samaneh Alavi, Bahram Dabir

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In this study, the removal of pollutants of a real produced water sample from an oil reservoir (a light oil reservoir), using a photocatalytic degradation process in a cylindrical glass reactor, was investigated. Using TiO₂ and Ag-TiO₂ in slurry form, the photocatalytic degradation was studied by measuring the COD parameter, qualitative analysis, and GC-MS. At first, optimization of the parameters on photocatalytic degradation of hydrocarbon pollutants in real produced water, using TiO₂ nanoparticles as photocatalysts under UV light, was carried out applying response surface methodology. The results of the design of the experiment showed that the optimum conditions were at a catalyst concentration of 1.14 g/lit and pH of 2.67, and the percentage of COD removal was 72.65%.

Keywords: photocatalyst, Ag-doped, TiO₂, produced water, nanoparticles

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Authors: Miao Yang

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PPCPs (pharmaceutical and personal care products) in water, as an environmental pollutant, becomes an issue of increasing concern. Therefore, the techniques for degradation of PPCPs has been a hotspot in water pollution control field. Since there are several disadvantages for common degradation techniques of PPCPs, such as low degradation efficiency for certain PPCPs (ibuprofen and Carbamazepine) this proposal will adopt a combined technique by using CDs (carbon nanodots)/C₃N₄ composite and ultrasonic irradiation to mitigate or overcome these shortages. There is a significant scientific problem that the mechanism including PPCPs, major reactants, and interfacial active sites is not clear yet in the study of PPCPs degradation. This work aims to solve this problem by using both theoretical and experimental methodologies. Firstly, optimized parameters will be obtained by evaluating the kinetics and oxidation efficiency under different conditions. The competition between H₂O₂ and PPCPs with HO• will be elucidated, after which the degradation mechanism of PPCPs by the synergy of CDs/C₃N₄ composite and ultrasonic irradiation will be proposed. Finally, a sonolysis-adsorption-catalysis coupling mechanism will be established which is the theoretical basis and technical support for developing new efficient degradation techniques for PPCPs in the future.

Keywords: carbon nanodots/C₃N₄, pharmaceutical and personal care products, ultrasonic irradiation, hydroxyl radical, heterogeneous catalysis

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Authors: Mohamed Gar Alalm, Shinichi Ookawara, Ahmed Tawfik

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In the present work, photocatalytic oxidation of phenol by iron (Fe+2) doped titanium dioxide (TiO2) was studied. The source of irradiation was solar simulated light under measured UV flux. The effect of light intensity, pH, catalyst loading, and initial concentration of phenol were investigated. The maximum removal of phenol at optimum conditions was 78%. The optimum pH was 5.3. The most effective degradation occurred when the catalyst dosage was 600 mg/L. increasing the initial concentration of phenol decreased the degradation efficiency due to the deactivation of active sites by additional intermediates. Phenol photocatalytic degradation moderately fitted to the pseudo-first order kinetic equation approximated from Langmuir–Hinshelwood model.

Keywords: phenol, photocatalytic, solar, titanium dioxide

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Authors: Vishakha Parihar

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This study reports the preparation of iron metal-doped nanoparticles of Titanium dioxide by the sol-gel process and the photocatalytic degradation of dye. Nano-particles were characterized by SEM, EDX, and UV-Vis spectroscopy. The detailed study confirmed that nanoparticles have grown in high density and have good optical properties. The photocatalytic batch experiment was performed in an aqueous solution where congo red dye was used as a dye pollutant under the irradiation of ultraviolet rays created by using a mercury lamp source. Total degradation efficiency achieved was approximately 85% to 93% in the duration of 100-120 minutes of irradiation under an ultraviolet light source. The decolorization ability of this process was measured by absorbance at a maximum wavelength of 498nm. The results indicated that the iron-doped Titanium dioxide nanoparticles showed an excellent photocatalytic response to the degradation of dye under the ultraviolet light source within a very short period of time.

Keywords: titanium dioxide, nano-particles iron dope, photocatalytic degradation, Congo red dye, sol-gel process

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Authors: Marta Chiapasco, Alexandra Porter, Finn Giuliani

Abstract:

Designing polymers with a specific microstructure can affect how the polymer degrades once released in the environment. Not only the amount but also the distribution of different phases determines a polymers’ degradability. The following research investigates the use of a combination of spectroscopy analysis and thermal analysis to study changes of polymers’ amorphous and crystalline phases during degradation, comparing different microstructures of polypropylene and polyethylene. The use of nanoindentation helps study how degradation proceeds across a material by looking at changes in phases, while bulk tensile test describes when the material fails. The first results demonstrate that different microstructures have different degrading rates, with homopolymer having a linear and faster degradation compared to copolymers. The goal is to create materials that degrade at faster rates without releasing microplastics into the environment.

Keywords: degradation, microstructure, nanoindentation, Raman spectroscopy

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Authors: Malek Ali

Abstract:

Composites materials of Poly (vinyl alcohol) (PVA)/Chitosan (CS) have been synthesized and characterized successfully. HNTs have been added to composites to enhance the mechanical and degradation properties by hydrogen bonding interactions, compatibility, and chemical crosslink between HNTs and PVA. PVA/CS/HNTs composites prepared with different concentration ratio. SEM micrographs of composites surface showed that more agglomeration with more chitosan ratio. Mechanical and degradation properties were characterized and the result indicates that Mechanical and degradation of 80%PVA/5%Chitosan/15%HNTs higher than the others PVA/CS/HNTs composites.

Keywords: PVA/chitosan, composites, PVA/CS/HNTs, HNTs

Procedia PDF Downloads 256