Search results for: photo degradation

Authors: Abdul Rahim Al Umairi, Mohamed Gamal El-Din

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The removal of the selected contaminants of emerging concerns (CECs) presented under related environmental conditions by Peracetic Acid (PAA) and PAA-UV photolysis processes was examined in this study. A mixture of (CECs) (pesticides and pharmaceutical compounds) was prepared inclean water and treated with different doses of PAA (3.2, 6.4, and 9.6 mg/L) under different pH values (5.2, 7.2, and 9.2). The results revealed that the reactivity of the selected CECs with PAA was classified into three groups: Group 1 poorly reactive (removal <25%), Group2 moderately reactive (removal 25% to 50%), and Group 3 highly reactive (> 50%). Group1 includes atrazine (ATZ) and fluconazole (FCL), Group2 includes carbamazepine (CBZ), sulfamethoxazole (SMX), trimethoprim (TMP), mecoprop (MCPP), diazinon (DZN) and Group 3 includes perfluorooctanoic acid (PFOA) and clindamycin (CLN). The pH was found to affect the CECs' degradation differently, for Group 1 and Group 3, better removal was achieved in the acidand alkaline medium. In contrast, for Group 2 pH effects were not well pronounced. PAA-UV photolysis processes were explored to degrade the recalcitrant indicators compounds: ATZ (Group1) and SMX(Group2). PAA-UV process showed no improvement in the removal of ATZ. In contrast, PAA-UV removed SMX drastically with a pseudo decay rate constant of 0.014 cm2/mJ compared to 0.002 cm2/mJ by UV alone. The contribution of hydroxyl radical to the degradation process using the PAA-UV process was found to be negligible. This study illustratedPAA's capability on the degradation of the CECs presented in relative environmental conditions and unveiled the potential of using PAA-UV processes as advanced oxidation processes.

Keywords: advanced oxidation process, contaminants of emerging concerns, peracetic acid, hydroxyl radical

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Authors: Johannes Bibinger, Sebastian Eibl, Hans-Joachim Gudladt

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This study considers the influence of different irradiation scenarios on the thermal degradation of carbon fiber-reinforced polymers (CFRP). Real threats are simulated, such as fires with long-lasting low heat fluxes and nuclear heat flashes with short-lasting high heat fluxes. For this purpose, coated and uncoated quasi-isotropic samples of the commercially available CFRP HexPly® 8552/IM7 are thermally irradiated from one side by a cone calorimeter and a xenon short-arc lamp with heat fluxes between 5 and 175 W/cm² at varying time intervals. The specimen temperature is recorded on the front and backside as well as at different laminate depths. The CFRP is non-destructively tested with ultrasonic testing, infrared spectroscopy (ATR-FTIR), scanning electron microscopy (SEM), and micro-focused computed X-Ray tomography (μCT). Destructive tests are performed to evaluate the mechanical properties in terms of interlaminar shear strength (ILSS), compressive and tensile strength. The irradiation scenarios vary significantly in heat flux and exposure time. Thus, different heating rates, radiation effects, and temperature distributions occur. This leads to unequal decomposition processes, which affect the sensitivity of the strength type and damage behaviour of the specimens. However, with the use of surface coatings, thermal degradation of composite materials can be delayed.

Keywords: CFRP, one-sided thermal damage, high heat flux, heating rate, non-destructive and destructive testing

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Authors: S. Divya, M. Jose

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Over the past years, industrial dyes have emerged as a significant threat to aquatic life, extensively detected in drinking water and groundwater, thus contributing to water pollution due to their improper and excessive use. To address this issue, the utilization of core-shell structures has been prioritized as it demonstrates remarkable efficiency in utilizing light energy for catalytic reactions and exhibiting excellent photocatalytic activity despite the availability of various photocatalysts. This work focuses on the photocatalytic degradation of Nd₂O₃@SiO₂ CSNs under UV light irradiation against MB and RhB dyes. Different characterization techniques, including XRD, FTIR, and TEM analyses, were employed to reveal the material's structure, functional groups, and morphological features. VSM and XPS analyses confirmed the soft, paramagnetic nature and chemical states with respective atomic percentages, respectively. Optical band gaps, determined using the Tauc plot model, indicated 4.24 eV and 4.13 eV for Nd₂O₃ NPs and Nd₂O₃@SiO₂ CSNs, respectively. The reduced bandgap energy of Nd₂O₃@SiO₂ CSNs enhances light absorption in the UV range, potentially leading to improved photocatalytic efficiency. The Nd₂O₃@SiO₂ CSNs exhibited greater degradation efficiency, reaching 95% and 96% against MB and RhB dyes, while Nd₂O₃ NPs showed 90% and 92%, respectively. The enhanced efficiency of Nd₂O₃@SiO₂ CSNs can be attributed to the larger specific surface area provided by the SiO₂ shell, as confirmed by surface area analysis using the BET surface area analyzer through N₂ adsorption-desorption.

Keywords: core shell nanocomposites, rare earth oxides, photocatalysis, advanced oxidation process

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Authors: Yingjeng James Li, Lung-Yu Sung, Huan-Jyun Ciou

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Durability of Membrane Electrode Assembly for Proton Exchange Membrane Fuel Cells was evaluated in both steady state and accelerated decay modes. Steady state mode was carried out at constant current of 800mA / cm2 for 2500 hours using air as cathode feed and pure hydrogen as anode feed. The degradation of the cell voltage was 0.015V after such 2500 hrs operation. The degradation rate was therefore calculated to be 6uV / hr. Accelerated mode was carried out by switching the voltage of the single cell between OCV and 0.2V. The durations held at OCV and 0.2V were 20 and 40 seconds, respectively, meaning one minute per cycle. No obvious change in performance of the MEA was observed after 10000 cycles of such operation.

Keywords: durability, lifetime, membrane electrode assembly, proton exchange membrane fuel cells

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Authors: Jinyoung Choi, Hyun-A Kim, Sunmook Lee

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The effects of environmental stress factors such as storage conditions on the deterioration phenomenon and the characteristic of the display glass were studied. In order to investigate the effect of chemical stress on the glass during the period of storage, the respective components of commercial glass were first identified by XRF (X-ray fluorescence). The glass was exposed in the acid, alkali, neutral environment for about one month. Thin film formed on the glass surface was analyzed by XRD (X-ray diffraction) and FT-IR (Fourier transform infrared). The degree of corrosion and the rate of deterioration of each sample were confirmed by measuring the concentrations of silicon, calcium and chromium with ICP-OES (Inductively coupled plasma-optical emission spectrometry). The optical properties of the glass surface were confirmed by SEM (Scanning electron microscope) before and after the treatment. Acknowledgement—The authors gratefully acknowledge the financial support from the Ministry of Trade, Industry and Energy (Grant Number: 10076817)

Keywords: corrosion, degradation test, display glass, environmental stress factor

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Authors: S. Shanthi

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Catalyzed oxidation processes show extraordinary guarantee for application in numerous wastewater treatment ranges. Advanced oxidation processes are emerging innovation that might be utilized for particular objectives in wastewater treatment. This research work provides a solution for removal a refractory organic compound 2,4-dichlorophenoxyaceticacid a common water pollutant. All studies were done in batch mode in a constantly stirred reactor. Alternative ozonation processes catalysed by transition metals or granular activated carbon have been investigated for degradation of organics. Catalytic ozonation under study are homogeneous catalytic ozonation, which is based on ozone activation by transition metal ions present in aqueous solution, and secondly as heterogeneous catalytic ozonation in the presence of Granular Activated Carbon (GAC). The present studies reveal that heterogeneous catalytic ozonation using GAC favour the ozonation of 2,4-dichlorophenoxyaceticacid by increasing the rate of ozonation and a much higher degradation of substrates were obtained in a given time. Be that it may, Fe2+and Fe3+ ions decreased the rate of degradation of 2,4-dichlorophenoxyaceticacid indicating that it acts as a negative catalyst. In case of heterogeneous catalytic ozonation using GAC catalyst it was found that during the initial 5 minutes of contact solution concentration decreased significantly as the pollutants were adsorbed initially. Thereafter the substrate started getting oxidized and ozonation became a dominates the treatment process. The exhausted GAC was found to be regenerated in situ. The percentage reduction of the substrate was maximum achieved in minimum possible time when GAC catalyst is employed.

Keywords: ozonation, homogeneous catalysis, heterogeneous catalysis, granular activated carbon

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Authors: Ayoola T. Brimmo, Mohamed I. Hassan

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The push to mitigate the aluminum smelting industry’s enormous energy consumption and high emission releases is now even more persistent with the recent climate change happenings. Common approaches to achieve this have been focused on improving energy efficiency in the pot line and cast house sections of the smelter. However, the conventional energy efficiency analyses are based on the first law of thermodynamics, which do not shed proper light on the smelter’s degradation of energy. This just gives a general idea of the furnace’s performance with no reference to locations where improvement is a possibility based on the second law of thermodynamics. In this study, we apply exergy analyses on the pot line and cast house sections of the smelter to identify the locality and causes of energy degradation. The exergy analyses, which are based on a real life smelter conditions, highlight the possible locations for technology improvement in a typical smelter. With this established, methods of minimizing the smelter’s exergy losses are assessed.

Keywords: exergy analysis, electrolytic cell, furnace, heat transfer

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Authors: Mohammad Anwar, Hamid Ullah Khan, Shah Waliullah

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Recently, environmental education is an essential element in avoiding environmental degradation around the globe that needs new articles and policymakers’ emphasis. Hence, the present article examines the impact of environmental education on environmental knowledge, environmental behavior, and environmental attitudes in Indonesia. The present research also investigated the moderating role of government support in environmental education, environmental knowledge, environmental behavior, and environmental attitude in Indonesia. A questionnaire was used as the primary data collection method. The smart PLS was utilized to test the association among variables and the hypotheses of the study. The results revealed that environmental education had a significant and positive linkage with environmental knowledge, environmental behavior, and environmental attitude in Indonesia. The findings also exposed that government support significantly moderated environmental education, environmental knowledge, and environmental behavior in Indonesia. The findings of this research would provide help to the policymakers in establishing the policies related to environmental education and reducing environmental degradation.

Keywords: environmental education, environmental knowledge, environmental behavior, environmental attitude, government support

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Authors: Joelle Penniston, E. B. Gueguim-Kana

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Biohydrogen has been identified as a promising alternative to the use of non-renewable fossil reserves, owing to its sustainability and non-polluting nature. pH is considered as a key parameter in fermentative biohydrogen production processes, due to its effect on the hydrogenase activity, metabolic activity as well as substrate hydrolysis. The present study assesses the influence of regulating pH on dark fermentative biohydrogen production. Four experimental hydrogen production schemes were evaluated. Two were implemented using suspended cells under regulated pH growth conditions (Sus_R) and suspended and non-regulated pH (Sus_N). The two others regimes consisted of alginate immobilized cells under pH regulated growth conditions (Imm_R) and immobilized and non-pH regulated conditions (Imm_N). All experiments were carried out at 37.5°C with glucose as sole source of carbon. Sus_R showed a lag time of 5 hours and a peak hydrogen fraction of 36% and a glucose degradation of 37%, compared to Sus_N which showed a peak hydrogen fraction of 44% and complete glucose degradation. Both suspended culture systems showed a higher peak biohydrogen fraction compared to the immobilized cell system. Imm_R experiments showed a lag phase of 8 hours, a peak biohydrogen fraction of 35%, while Imm_N showed a lag phase of 5 hours, a peak biohydrogen fraction of 22%. 100% glucose degradation was observed in both pH regulated and non-regulated processes. This study showed that biohydrogen production in batch mode with suspended cells in a non-regulated pH environment results in a partial degradation of substrate, with lower yield. This scheme has been the culture mode of choice for most reported studies in biohydrogen research. The relatively lower slope in pH trend of the non-regulated pH experiment with immobilized cells (Imm_N) compared to Sus_N revealed that that immobilized systems have a better buffering capacity compared to suspended systems, which allows for the extended production of biohydrogen even under non-regulated pH conditions. However, alginate immobilized cultures in flask systems showed some drawbacks associated to high rate of gas production that leads to increased buoyancy of the immobilization beads. This ultimately impedes the release of gas out of the flask.

Keywords: biohydrogen, sustainability, suspended, immobilized

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Authors: María José Patiño-Ropero, Manuel Alcamí, Al Mokhtar Lamsabhi, José Luis Alonso-Prados, Pilar Sandín-España

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Tralkoxydim, commercialized under different trade names, among them Splendor® (25% active ingredient), is a cyclohexanedione herbicide used in wheat and barley fields for the post-emergence control of annual winter grass weeds. Due to their physicochemical properties, herbicides belonging to this family are known to be susceptible to reaching natural waters, where different degradation pathways can take place. Photolysis represents one of the main routes of abiotic degradation of these herbicides in water. This transformation pathway can lead to the formation of unknown by-products, which could be more toxic and/or persistent than the active substances themselves. Therefore, there is a growing need to understand the science behind such dissipation routes, which is key to estimating the persistence of these compounds and ensuring the accurate assessment of environmental behavior. However, to our best knowledge, any information regarding the photochemical behavior of tralkoxydim under natural conditions in an aqueous environment has not been available till now in the literature. This work has focused on investigating the photochemical behavior of tralkoxydim herbicide and its commercial formulation (Splendor®) in the ultrapure, river and spring water using simulated solar radiation. Besides, the evolution of detected degradation products formed in the samples has been studied. A reversed-phase HPLC-DAD (high-performance liquid chromatography with diode array detector) method was developed to evaluate the kinetic evolution and to obtain the half-lives. In both cases, the degradation rates of active ingredient tralkoxydim in natural waters were lower than in ultrapure water following the order; river water < spring water < ultrapure water, and with first-order half-life values of 5.1 h, 2.7 h and 1.1 h, respectively. These findings indicate that the photolytical behavior of active ingredients is largely affected by the water composition, and these components can exert an internal filter effect. In addition, tralkoxydim herbicide and its formulation showed the same half-lives for each one of the types of water studied, showing that the presence of adjuvants in the commercial formulation has not any effect on the degradation rates of the active ingredient. HPLC-MS (high-performance liquid chromatography with mass spectrometry) experiments were performed to study the by-products deriving from the photodegradation of tralkoxydim in water. Accordingly, three compounds were tentatively identified. These results provide a better understanding of the tralkoxydim herbicide behavior in natural waters and its fate in the environment.

Keywords: by-products, natural waters, photodegradation, tralkoxydim herbicide

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Authors: Hao Yang, Lei Chen, Ting Mei, Jianbang Zheng

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Currently, the uncooled PbSe photodetectors in the mid-infrared range (2-5μm) with sensitization technology extract more photoelectric response than traditional ones, and enable the room temperature (300K) photo-detection with high detectivity, which have attracted wide attentions in many fields. This technology generally contains the film fabrication with vapor phase deposition (VPD) and a sensitizing process with doping of oxygen and iodine. Many works presented in the recent years almost provide and high temperature activation method with oxygen/iodine vapor diffusion, which reveals that oxygen or iodine plays an important role in the sensitization of PbSe material. In this paper, we provide our latest experimental results and discussions in the stoichiometry of oxygen and iodine and its influence on the polycrystalline structure and photo-response. The experimental results revealed that crystal orientation was transformed from (200) to (420) by sensitization, and the responsivity of 5.42 A/W was gained by the optimal stoichiometry of oxygen and iodine with molecular density of I2 of ~1.51×1012 mm-3 and oxygen pressure of ~1Mpa. We verified that I2 plays a role in transporting oxygen into the lattice of crystal, which is actually not its major role. It is revealed that samples sensitized with iodine transform atomic proportion of Pb from 34.5% to 25.0% compared with samples without iodine from XPS data, which result in the proportion of about 1:1 between Pb and Se atoms by sublimation of PbI2 during sensitization process, and Pb/Se atomic proportion is controlled by I/O atomic proportion in the polycrystalline grains, which is very an important factor for improving responsivity of uncooled PbSe photodetector. Moreover, a novel sensitization and dopant activation method is proposed using oxygen ion implantation with low ion energy of < 500eV and beam current of ~120μA/cm2. These results may be helpful to understanding the sensitization mechanism of polycrystalline lead salt materials.

Keywords: polycrystalline PbSe, sensitization, transport, stoichiometry

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Authors: Humaira Khan, Mohsin Javed, Sammia Shahid

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The reinforced photocatalytic activity of graphene oxide (GO) along with composites of ZnO nanoparticles and copper-doped ZnO nanoparticles were studied by synthesizing ZnO and copper- doped ZnO nanoparticles by co-precipitation method. Zinc acetate and copper acetate were used as precursors, whereas graphene oxide was prepared from pre-oxidized graphite in the presence of H2O2.The supernatant was collected carefully and showed high-quality single-layer characterized by FTIR (Fourier Transform Infrared Spectroscopy), TEM (Transmission Electron Microscopy), SEM (Scanning Electron Microscopy), XRD (X-ray Diffraction Analysis), EDS (Energy Dispersive Spectrometry). The degradation of methylene blue as standard pollutant under UV-Visible irradiation gave results for photocatalytic activity of dopants. It could be concluded that shrinking of optical band caused by composites of Cu-dopped nanoparticles with GO enhances the photocatalytic activity.

Keywords: degradation, graphene oxide, photocatalysis, ZnO nanoparticles and copper-doped ZnO nanoparticles

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Authors: Hui-Hsin Huang, Yi-Feng Lin, Che-Chia Hu

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To date, photocatalytic wastewater treatment using solar energy has attracted considerable attention. In this study, strontium titanates with various morphologies, i.e., nanofibers and cubic-like particles, were prepared as photocatalysts using the electrospinning (ES), solid-state (SS), and sol-gel (SG) methods. X-ray diffraction (XRD) analysis showed that ES and SS can be assigned to pure phase SrTiO3, while SG was referred to Sr2TiO4. These samples displayed optical absorption edges at 385-395 nm, indicating they can be activated in UV light irradiation. Scanning electron microscope (SEM) analyses revealed that ES SrTiO3 has a uniform fibrous structure with length and diameter of several microns and 100-200 nm, respectively. After loading of nanoparticulate Ag as a co-catalyst onto the surface of strontium titanates, ES sample exhibited highest photocatalytic activity to degrade methylene orange dye solution in comparison to that of SS and SG ones. These results indicate that Ag-loaded ES SrTiO3, which has a desirable SrTiO3 phase and a facile electron transfer along the preferential direction in fibrous structure, can be a promising photocatalyst.

Keywords: photocatalytic degradation, strontium titanate, electrospinning, co-catalyst

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Authors: Jigar Shaileshumar Halpati, Aravind Kumar Chandiran

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Vacancy ordered double perovskites (VOPs) have been significantly attracting researchers due to their chemical structure diversity and interesting optoelectronic properties. Some VOPs have been recently reported to be suitable photoelectrodes for photoelectrochemical water-splitting reactions due to their high stability and panchromatic absorption. In this work, we systematically synthesized mixed tetravalent VOPs based on Cs₂RuₘPt₁-ₘX₆ (X = Cl-, Br-) and reported their structural, optical, electrochemical and photoelectrochemical properties. The structural characterization confirms that the mixed tetravalent site intermediates formed their own phases. The parent materials, as well as their intermediates, were found to be stable in ambient conditions for over 1 year and also showed incredible stability in harsh pH media ranging from pH 1 to pH 11. Moreover, these materials showed panchromatic absorption with onset up to 1000 nm depending upon the mixture stoichiometry. The extraordinary stability and excellent absorption properties make them suitable materials for photoelectrochemical water-splitting applications. PEC studies of these series of materials showed a high water oxidation photocurrent of 0.56 mA cm-² for Cs₂Ru₀.₅Pt₀.₅Cl₆. Fundamental investigation from photoelectrochemical reactions revealed that the intrinsic ruthenium-based VOP showed enhanced hole transfer to the electrolyte, while the intrinsic platinum-based VOP showed higher photovoltage. The mix of these end members at the tetravalent site showed a synergic effect of reduced charge transfer resistance from the material to the electrolyte and increased photovoltage, which led to increased PEC performance of the intermediate materials.

Keywords: solar water splitting, photo electrochemistry, photo absorbers, material characterization, device characterization, green hydrogen

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Authors: Wandera Stephen Ojumbo

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People living with hearing impairment in Uganda are one of the most excluded minority groups in the country. The Uganda National Association of the Deaf estimates that deaf people make up 3.4% of Uganda’s 43 million people. Deaf Children and youth often appear withdrawn because they face social stigma. In 2009, photojournalist Stephen Wandera Ojumbo conducted an exhibition in Kampala titled “Silent Voices with colourful Hearts” showcasing the life of deaf children at Uganda School for the Deaf, Ntinda, in order to create awareness of their plight, raising funds for the construction of a vocational centre for the deaf that didn’t continue their education due to: lack of funds, non-inclusive educational institutions, and for those who cannot read and write. These children, whose lives were exhibited in 2009, are currently youths. In Uganda, there are just five primary schools for the deaf (three of these are located in Kampala, the capital city), and barely five secondary schools for the deaf. At the moment, some deaf children only receive special needs training equivalent to primary seven levels and the majority don’t make it to secondary school education level due to the fact that English is a second language to them. There is a communication gap between speaking parents and deaf children, which leads to the breakage of family bonds. The deaf youth run away from their homes to form a community where they can communicate freely. Likewise, employment opportunities for the deaf are equally very limited. It’s for this reason that a follow-up photo exhibition was conducted to expose more about what the youthful deaf people and their guardians go through in Uganda to get jobs, live and fit in the community, how they communicate and get understood, bonding with families instead of running away to bond with fellow deaf persons. The photo exhibition under the theme “Loud Silence” was significant in showcasing the ability of deaf youths in Uganda and eliciting solutions to make a more inclusive society for the deaf. It is hoped that partners in development will join in for intervention. The methodology used included individual interviews with the deaf youth and their parents and caretakers; photography at household and community levels; document review at organizations working with the deaf; observations; and key informant interviews with relevant personnel working with the deaf. Some of the major findings include: i) Effective sign language communication is key in deaf education, family bonding, and developing a sense of belonging; ii) Love and intimacy can keep the deaf bound together; iii) Education is important; everybody should struggle even if alone; iv) Games and sports are a unifying factor and most loved among the deaf; and v) better communication skills build confidence in deaf youth. In conclusion, concerted efforts are still needed to make Uganda schools more inclusive for deaf persons. This will enable a secure future for deaf youths.

Keywords: deaf, education, excluded, photo exhibition

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Authors: Arun Karoriya, Mrinal Agrawal

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Health is one of the basic requirements of human being. And today India is facing a major degradation of health at every age group. As society evolves and flourishes, there are different types of rules, norms, standards which are required to control the conduct of the human being for its well-being and growth. Right to health is one of those aspects that can be counted, discovered and examined under the purview of constitutional provisions of India. The condition of health is at downfall despite the fact that there are several policies framed by the government. There is an urgent call for rigid public health laws to ensure safe and disease free society. The effectiveness of health law has to be examined by keeping in mind that it is hampering growth and economy and society establishment. Health in any society is a main social aspect as it plays a major role for economic development. The multidimensional approach to determine it is by discussing i) rational selection and use of medicines ii) sustainable adequate financing iii) affordable prices iv)reliable health and supply systems.

Keywords: degradation, flourish, multidimensional, policies

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Authors: HoYoung Son, DongHoon Shin, WooYoung Jung

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This study presented the seismic fragility framework of concrete weir structure subjected to strong seismic ground motions and in particular, concrete aging condition of the weir structure was taken into account in this study. In order to understand the influence of concrete aging on the weir structure, by using probabilistic risk assessment, the analytical seismic fragility of the weir structure was derived for pre- and post-deterioration of concrete. The performance of concrete weir structure after five years was assumed for the concrete aging or deterioration, and according to after five years’ condition, the elastic modulus was simply reduced about one–tenth compared with initial condition of weir structures. A 2D nonlinear finite element analysis was performed considering the deterioration of concrete in weir structures using ABAQUS platform, a commercial structural analysis program. Simplified concrete degradation was resulted in the increase of almost 45% of the probability of failure at Limit State 3, in comparison to initial construction stage, by analyzing the seismic fragility.

Keywords: weir, FEM, concrete, fragility, aging

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Authors: M. S. Meon, M. N. Rao, K-U. Schröder

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Mechanical fasteners especially bolting is commonly used in joining carbon-fiber reinforced polymer (CFRP) composite structures due to their good joinability and easy for maintenance characteristics. Since this approach involves with notching, a proper progressive damage model (PDM) need to be implemented and verified to capture existence of damages in the structure. A three dimensional (3D) failure criteria of Puck is established to predict the ultimate bearing failure of such joint. The failure criteria incorporated with degradation scheme are coded based on user subroutine executed in Abaqus. Single lap joint (SLJ) of composite bolted joint is used as target configuration. The results revealed that the PDM adopted here could sufficiently predict the behaviour of composite bolted joint up to ultimate bearing failure. In addition, mesh refinement near holes increased the accuracy of predicted strength as well as computational effort.

Keywords: bearing strength, bolted joint, degradation scheme, progressive damage model

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Authors: S. V. Prabhakar Vattikuti, Chan Byon

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In this paper, we report a facile synthetic strategy of randomly disturbed Bi₂S₃ nanorods on WS₂ nanosheets, which are synthesized via a controlled hydrothermal method without surfactant under an inert atmosphere. We developed a simple hydrothermal method for the formation of heterostructured of Bi₂S₃/WS₂ with a large scale (>95%). The structural features, composition, and morphology were characterized by XRD, SEM-EDX, TEM, HRTEM, XPS, UV-vis spectroscopy, N₂ adsorption-desorption, and TG-DTA measurements. The heterostructured Bi₂S₃/WS₂ composite has significant photocatalytic efficiency toward the photodegradation of organic dye. The time-dependent UV-vis absorbance spectroscopy measurement was consistent with the enhanced photocatalytic degradation of rhodamine B (RhB) under visible light irradiation with the diminishing carrier recombination for the Bi₂S₃/WS₂ photocatalyst. Due to their marked synergistic effects, the supported Bi₂S₃ nanorods on WS₂ nanosheet heterostructures exhibit significant visible-light photocatalytic activity and stability for the degradation of RhB. A possible reaction mechanism is proposed for the Bi₂S₃/WS₂ composite.

Keywords: photocatalyst, heterostructures, transition metal disulfides, organic dye, nanorods

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Authors: Nabil Jallouli, Luisa M. Pastrana-Martínez, Ana R. Ribeiro, Nuno F. F. Moreira, Joaquim L. Faria, Olfa Hentati, Adrián M. T. Silva, Mohamed Ksibi

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Degradation and mineralization of ibuprofen (IBU) were investigated using Ultraviolet (UV) Light Emitting Diodes (LEDs) in TiO2 photocatalysis. Samples of ultrapure water (UP) and a secondary treated effluent of a municipal wastewater treatment plant (WWTP), both spiked with IBU, as well as a highly concentrated IBU (230 mgL-1) pharmaceutical industry wastewater (PIWW), were tested in the TiO2/UV-LED system. Three operating parameters, namely, pH, catalyst load and number of LEDs were optimized. The process efficiency was evaluated in terms of IBU removal using high performance liquid chromatography (HPLC) and ultra-high performance liquid chromatography coupled to tandem mass spectrometry (UHPLC-MS/MS). Additionally, the mineralization was investigated by determining the dissolved organic carbon (DOC) content. The chemical structures of transformation products were proposed based on the data obtained using liquid chromatography with a high resolution mass spectrometer ion trap/time-of-flight (LC-MS-IT-TOF). A possible pathway of IBU degradation was accordingly proposed. Bioassays were performed using the marine bacterium Vibrio fischeri to evaluate the potential acute toxicity of original and treated wastewaters. TiO2 heterogeneous photocatalysis was efficient to remove IBU from UP and from PIWW, and less efficient in treating the wastewater from the municipal WWTP. The acute toxicity decreased by ca. 40% after treatment, regardless of the studied matrix.

Keywords: acute toxicity, Ibuprofen, UV-LEDs, wastewaters

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Authors: Rhoda Afriyie Mensah, Lin Jiang, Solomon Asante-Okyere, Xu Qiang, Cong Jin

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Flammability analysis of extruded polystyrene (XPS) has become crucial due to its utilization as insulation material for energy efficient buildings. Using the Kissinger-Akahira-Sunose and Flynn-Wall-Ozawa methods, the degradation kinetics of two pure XPS from the local market, red and grey ones, were obtained from the results of thermogravity analysis (TG) and microscale combustion calorimetry (MCC) experiments performed under the same heating rates. From the experiments, it was discovered that red XPS released more heat than grey XPS and both materials showed two mass loss stages. Consequently, the kinetic parameters for red XPS were higher than grey XPS. A comparative evaluation of activation energies from MCC and TG showed an insignificant degree of deviation signifying an equivalent apparent activation energy from both methods. However, different activation energy profiles as a result of the different chemical pathways were presented when the dependencies of the activation energies on extent of conversion for TG and MCC were compared.

Keywords: flammability, microscale combustion calorimetry, thermogravity analysis, thermal degradation, kinetic analysis

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Authors: Ghadeer Jalloul, Nour Hijazi, Cassia Boyadjian, Hussein Awala, Mohammad N. Ahmad, ‎Ahmad Albadarin

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In this study, we applied Fe-sensitized TiO₂ supported over embryonic Beta zeolite (BEA) zeolite ‎for the photocatalytic degradation of Tetracycline (TC) antibiotic under visible light. Four different ‎samples having 20, 40, 60, and 100% w/w as a ratio of TiO₂/BEA were prepared. The ‎immobilization of solgel TiO₂ (33 m²/g) over BEA (390 m²/g) increased its surface area to (227 ‎m²/g) and enhanced its adsorption capacity from 8% to 19%. To expand the activity of TiO₂ ‎photocatalyst towards the visible light region (λ>380 nm), we explored two different metal ‎sensitization techniques with Iron ions (Fe³⁺). In the ion-exchange method, the substitutional cations ‎in the zeolite in TiO₂/BEA were exchanged with (Fe³⁺) in an aqueous solution of FeCl₃. In the ‎doping technique, solgel TiO₂ was doped with (Fe³⁺) from FeCl₃ precursor during its synthesis and ‎before its immobilization over BEA. (Fe-TiO₂/BEA) catalysts were characterized using SEM, XRD, ‎BET, UV-VIS DRS, and FTIR. After testing the performance of the various ion-exchanged catalysts ‎under blue and white lights, only (Fe-TiO₂/BEA 60%) showed better activity as compared to pure ‎TiO₂ under white light with 100 ppm initial catalyst concentration and 20 ppm TC concentration. As ‎compared to ion-exchanged (Fe-TiO₂/BEA), doped (Fe-TiO₂/BEA) resulted in higher photocatalytic ‎efficiencies under blue and white lights. The 3%-Fe-doped TiO₂/BEA removed 92% of TC ‎compared to 54% by TiO₂ under white light. The catalysts were also tested under real solar ‎irradiations. This improvement in the photocatalytic performance of TiO₂ was due to its higher ‎adsorption capacity due to BEA support combined with the presence of Iron ions that enhance the ‎visible light absorption and minimize the recombination effect by the charge carriers. ‎

Keywords: Tetracycline, photocatalytic degradation, immobilized TiO₂, zeolite, iron-doped TiO₂, ion-exchange

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Authors: Lalita, Niladri Sarkar, Subhasis Ghosh

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Since the discovery of high temperature superconductivity (HTSC) in cuprates, several aspects of this phenomena have fascinated physics community. The most debated one is the linear temperature dependence of normal state resistivity over wide range of temperature in violation of with Fermi liquid theory. The linear-in-T resistivity (LITR) is the indication of strongly correlated metallic, known as “strange metal”, attributed to non Fermi liquid theory (NFL). The proximity of superconductivity to LITR suggests that there may be underlying common origin. The LITR has been shown to be due to unknown dissipative phenomena, restricted by quantum mechanics and commonly known as ‘‘Planckian dissipation” , the term first coined by Zaanen and the associated inelastic scattering time τ and given by 1/τ=αkBT/ℏ, where ℏ, kB and α are reduced Planck’s constant, Boltzmann constant and a dimensionless constant of order of unity, respectively. Since the first report, experimental support for α ~ 1 is appearing in literature. There are several striking issues which remain to be resolved if we desire to find out or at least get a clue towards microscopic origin of maximal dissipation in cuprates. (i) Universality of α ~ 1, recently some doubts have been raised in some cases. (ii) So far, Planckian dissipation has been demonstrated in overdoped Cuprates, but if the proximity to quantum criticality is important, then Planckian dissipation should be observed in optimally doped and marginally underdoped cuprates. The link between Planckian dissipation and quantum criticality still remains an open problem. (iii) Validity of Planckian dissipation in all cuprates is an important issue. Here, we report reversible change in the superconducting behavior of high temperature superconductor Bi2Sr2Ca2Cu3O10+δ (Bi-2223) under dynamic doping induced by photo-excitation. Two doped Bi-223 samples, which are x = 0.16 (optimal-doped), x = 0.145 (marginal-doped) have been used for this investigation. It is realized that steady state photo-excitation converts magnetic Cu2+ ions to nonmagnetic Cu1+ ions which reduces superconducting transition temperature (Tc) by killing superfluid density. In Bi-2223, one would expect the maximum of suppression of Tc should be at charge transfer gap. We have observed suppression of Tc starts at 2eV, which is the charge transfer gap in Bi-2223. We attribute this transition due to Cu-3d9(Cu2+) to Cu-3d10(Cu+), known as d9 − d10 L transition, photoexcitation makes some Cu ions in CuO2 planes as spinless non-magnetic potential perturbation as Zn2+ does in CuO2 plane in case Zn-doped cuprates. The resistivity varies linearly with temperature with or without photo-excitation. Tc can be varied by almost by 40K be photoexcitation. Superconductivity can be destroyed completely by introducing ≈ 2% of Cu1+ ions for this range of doping. With this controlled variation of Tc and resistivity, detailed investigation has been carried out to reveal Planckian dissipation underdoped to optimally doped Bi-2223. The most important aspect of this investigation is that we could vary Tc dynamically and reversibly, so that LITR and associated Planckian dissipation can be studied over wide ranges of Tc without changing the doping chemically.

Keywords: linear resistivity, HTSC, Planckian dissipation, strange metal

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Authors: Geeta Negi, Pankaj, Anjana Srivastava, Anita Sharma

Abstract:

In the present study, the presence of endosulfan, imidacloprid, carbendazim, in the soil /vegetables/cereals and water samples was observed in agriculture fields of Uttarakhand. In view of biodegradation of these pesticides, nine bacterial isolates were recovered from the soil samples of the fields which tolerated endosulfan, imidacloprid, carbendazim from 100 to 200 µg/ml. Three bacterial consortia used for in vitro bioremediation experiments were three bacterial isolates for carbendazim, imidacloprid and endosulfan, respectively. Maximum degradation (87 and 83%) of α and β endosulfan respectively was observed in soil slurry by consortium. Degradation of Imidacloprid and carbendazim under similar conditions was 88.4 and 77.5% respectively. FT-IR analysis of biodegraded samples of pesticides in liquid media showed stretching of various bonds. GC-MS of biodegraded endosulfan sample in soil slurry showed the presence of non-toxic intermediates. A pot trial with Bacterial treatments lowered down the uptake of pesticides in onion plants.

Keywords: biodegradation, carbendazim, consortium, endosulfan

Procedia PDF Downloads 347

Authors: Nibedita Pani, Vishnu Tejani, T. S. Anantha Singh

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Water pollution resulting from discharge of partial/not treated textile wastewater containing high carbon and nitrogen pollutants pose a huge threat to the environment, ecosystem, and human health. It is essential to remove carbon- and nitrogen-based organic pollutants more effectively from industrial wastewater before discharging. The present study focuses on removal of carbon-based pollutant in particular COD (chemical oxygen demand) and nitrogen-based pollutants, in particular, ammoniacal nitrogen by Fenton oxidation process using Fe²⁺ and H₂O₂ as reagents. The study was carried out with high strength wastewater containing initial COD 5632 mg/L and NH⁴⁺-N 1372 mg/L. The major operating condition like pH was varied between 1.0 to 4.0. The maximum degradation was obtained at pH 3.0 taking the molar ratio of Fe²⁺/H₂O₂ as 1:1. At this pH, the removal efficiencies of COD and ammoniacal nitrogen were found to be 77.27% and 74.9%, respectively. The Fenton process can be the best alternative for the simultaneous removal of COD and NH4+-N from industrial wastewater.

Keywords: ammoniacal nitrogen, COD, Fenton oxidation, industrial wastewater

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Authors: A. Natsir, M. Nadir, S. Syahrir, A. Mujnisa, N. Purnomo, A. R. Egan, B. J. Leury

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Rumen degradation characteristic of feedstuff is one of the prominent factors affecting microbial population in rumen of animal. High rumen degradation rate of faba bean protein may lead to inconstant rumen conditions that could have a prominent impact on rumen microbial diversity. Amplified Ribosomal DNA Restriction Analysis (ARDRA) is utilized to monitor diversity of rumen microbes on sheep fed low quality forage supplemented by faba beans. Four mature merino sheep with existing rumen cannula were used in this study according to 4 x 4 Latin square design. The results of study indicated that there were 37 different ARDRA types identified out of 136 clones examined. Among those clones, five main clone types existed across the treatments with different percentages. In conclusion, the ARDRA method is potential to be used as a routine tool to assess the temporary changes in the rumen community as a result of different feeding strategies.

Keywords: ARDRA method, cattle, genomic diversity, rumen microbes

Procedia PDF Downloads 331

Authors: S. K. M. Nzaba, H. H. Nyoni, B. Ntsendwana, B. B. Mamba, A. T. Kuvarega

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Azo dye effluents, released into water bodies are not only toxic to the ecosystem but also pose a serious impact on human health due to the carcinogenic and mutagenic effects of the compounds present in the dye discharge. Conventional water treatment methods such as adsorption, flocculation/coagulation and biological processes are not effective in completely removing most of the dyes and their natural degradation by-products. Advanced oxidation processes (AOPs) have proven to be effective technologies for complete mineralization of these recalcitrant pollutants. Therefore, there is a need for new technology that can solve the problem. Thus, this study examined the photocatalytic degradation of an azo dye brilliant black (BB) using non-metal/metal codoped TiO₂. N, Pt co-doped TiO₂ photocatalysts were prepared by a modified sol-gel method using amine-terminated polyamidoamine dendrimer generation 0 (PAMAM G0), amine-terminated polyamidoamine dendrimer generation 1 ( PAMAM G1) and hyperbranched polyethyleneimine (HPEI) as templates and source of nitrogen. Structural, morphological, and textural properties were evaluated using scanning electron microscopy coupled to energy dispersive X-ray spectroscopy (SEM/EDX), high-resolution transmission electron microscopy (HRTEM), X-ray diffraction spectroscopy (XRD), X-ray photoelectron spectroscopy (XPS), thermal gravimetric analysis (TGA), Fourier- transform infrared (FTIR), Raman spectroscopy (RS), photoluminescence (PL) and ultra-violet /visible spectroscopy (UV-Vis). The synthesized photocatalysts exhibited lower band gap energies as compared to the Degussa P-25 revealing a red shift in band gap towards the visible light absorption region. Photocatalytic activity of N, Pt co-doped TiO₂ was measured by the reaction of photocatalytic degradation of brilliant black (BB) dye. The N, metal codoped TiO₂ containing 0.5 wt. % of the metal consisted mainly of the anatase phase as confirmed by XRD results of all three samples, with a particle size range of 13–30 nm. The particles were largely spherical and shifted the absorption edge well into the visible region. Band gap reduction was more pronounced for the N, Pt HPEI (Pt 0.5 wt. %) codoped TiO₂ compared to PAMAM G0 and PAMAM G1. Consequently, codoping led to an enhancement in the photocatalytic activity of the materials for the degradation of brilliant black (BB).

Keywords: codoped TiO₂, dendrimer, photodegradation, wastewater

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Authors: Layane Sara Vieira, Paulo Egidio Bernardo, Roberto Saverio Souza Costa

Abstract:

Anthropogenic occupations and agricultural explorations without concern for the preservation and sustainability of the activity result in soil degradation that can make rural activity unfeasible. The objective of this work was to characterize and evaluate the recovery costs of an area degraded by major erosion (gully) in the municipality of Monte Alto (SP). Topographic characterization was carried out by means of a planialtimetric survey with a total station. The contours of the gully, internal area, slope height, contribution area, volume, and costs of operations for the recovery of the gully were delimited. The results obtained showed that the gully has a length of 145.56 m, a maximum width of 36.61 m, and a gap of 19.48 m. The external area of the gully is 1,039.8741 m², and the internal area is 119.3470 m². The calculated volume was 3,282.63 m³. The intervention area for breaking slopes was measured at 8,471.29 m², requiring the construction of 19 terraces in this area, vertically spaced at 2.8 m. The estimated costs for mechanical recovery of the gully were R$ 19,167.84 (US$ 3.657,98).

Keywords: erosion, volumetric assessment, soil degradation, terraces

Procedia PDF Downloads 78

Authors: Jihuai Wu, Zeyu Song, Zhang Lan, Liuxue Sun

Abstract:

Solar energy is clean, open, and infinite, but solar radiation on the earth is fluctuating, intermittent, and unstable. So, the sustainable utilization of solar energy requires a combination of high-efficient energy conversion and low-loss energy storage technologies. Hence, a photo capacitor integrated with photo-electrical conversion and electric-chemical storage functions in single device is a cost-effective, volume-effective and functional-effective optimal choice. However, owing to the multiple components, multi-dimensional structure and multiple functions in one device, especially the mismatch of the functional modules, the overall conversion and storage efficiency of the photocapacitors is less than 13%, which seriously limits the development of the integrated system of solar conversion and energy storage. To this end, two typical photocapacitors were studied. A three-terminal photocapacitor was integrated by using perovskite solar cell as solar conversion module and symmetrical supercapacitor as energy storage module. A function portfolio management concept was proposed the relationship among various efficiencies during photovoltaic conversion and energy storage process were clarified. By harmonizing the energy matching between conversion and storage modules and seeking the maximum power points coincide and the maximum efficiency points synchronize, the overall efficiency of the photocapacitor surpassed 18 %, and Joule efficiency was closed to 90%. A voltage adjustable hybrid supercapacitor (VAHSC) was designed as energy storage module, and two Si wafers in series as solar conversion module, a three-terminal photocapacitor was fabricated. The VAHSC effectively harmonizes the energy harvest and storage modules, resulting in the current, voltage, power, and energy match between both modules. The optimal photocapacitor achieved an overall efficiency of 15.49% and Joule efficiency of 86.01%, along with excellent charge/discharge cycle stability. In addition, the Joule efficiency (ηJoule) was defined as the energy ratio of discharge/charge of the devices for the first time.

Keywords: joule efficiency, perovskite solar cell, photocapacitor, silicon solar cell, supercapacitor

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Authors: Ertuğ Yıldırım, Dile Kara, Salih Zeki Yıldız

Abstract:

Metal containing polymers (MCPs) are macro molecules usually containing metal-ligand coordination units and are a multidisciplinary research field mainly based at the interface between coordination chemistry and polymer science. The progress of this area has also been reinforced by the growth of several other closely related disciplines including macro molecular engineering, crystal engineering, organic synthesis, supra molecular chemistry and colloidal and material science. Schiff base ligands are very effective in constructing supra molecular architectures such as coordination polymers, double helical and triple helical complexes. In addition, Schiff base derivatives incorporating a fluorescent moiety are appealing tools for optical sensing of metal ions. MCPs are well-known systems in which the combinations of local parameters are possible by means of fluoro metric techniques. Generally, without incorporation of the fluorescent groups with polymers is unspecific, and it is not useful to analyze their fluorescent properties. Therefore, it is necessary to prepare a new type epoxy polymers with fluorescent groups in terms of metal sensing prop and the other photo chemical applications. In the present study metal containing polymers were prepared via poly functional monomeric Schiff base metal chelate complexes in the presence of dis functional monomers such as diglycidyl ether Bisphenol A (DGEBA). The synthesized complexes and polymers were characterized by FTIR, UV-VIS and mass spectroscopies. The preparations of epoxy polymers have been carried out at 185 °C. The prepared composites having sharp and narrow excitation/emission properties are expected to be applicable in various systems such as heat-resistant polymers and photo voltaic devices. The prepared composite is also ideal for various applications, easily prepared, safe, and maintain good fluorescence properties.

Keywords: Schiff base ligands, crystal engineering, fluorescence properties, Metal Containing Polymers (MCPs)

Procedia PDF Downloads 324