Search results for: Metal Organic Frameworks

Authors: Blessings Masuku

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Background: Considering that Africa is urbanizing faster than any other region globally, managing cities in the global South has become the centerpiece for the New Urban Agenda (i.e., a shared vision of how we rethink, rebuild, and manage our cities for a better and more sustainable future). This study is centered on governance and planning of urban informality practices with particular reference to the relationship between the state, informal actors (e.g., informal traders and informal dwellers), and other city stakeholders who are public space users (commuters, businesses, and environmental activists), and how informal actors organize themselves to lobby the state and claim for their rights in the city, and how they navigate their everyday livelihood strategies. Aim: The purpose of this study is to examine and interrogate contemporary approaches, policy and regulatory frameworks to urban spatial planning and management of informality in one of South Africa’s busiest and major cities, Johannesburg. Setting: The study uses the metropolitan region of the city of Johannesburg, South Africa to understand how this contemporary industrial city manages urban informality practices, including the use of public space, land zoning and street life, and paying a closer look at what progress has been made and gaps in their inclusive urban policy frameworks. Methods: This study utilized a qualitative approach that includes surveys (open-ended questions), archival research (i., e policy and other key document reviews), and key interviews mainly with city officials, and informality actors. A thematic analysis was used to analyze the data collected. Contribution: This study contributes to large urban informality scholarship in the global South cities by exploring how major cities particularly in Africa regulate and manage informality patterns and practices in their quest to build “utopian” smart cities. This study also brings a different perspective on the hacking ways used by the informal actors to resist harsh regulations and remain invisible in the city, which is something that previous literature has barely delved in-depth.

Keywords: inclusive planning and governance, infrastructure systems, livelihood strategies urban informality, urban space

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Authors: Rabih O. Al-Kaysi, Lingyan Zhu, Muhannah K. Al-Muhannah, Christopher J. Bardeen

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(E)-3-(Anthracen-9-yl)acrylic acid (9-AYAA) 1 exhibits a strong photomechanical response in bulk crystals but is challenging to grow in microcrystalline form. High quality microcrystals of this molecule could not be grown using techniques like sublimation, reprecipitation, and the floating drop method. If the tertbutyl ester of 9-AYAA is used as a starting material, however, high quality, size-uniform microwires could be grown via acid catalyzed hydrolysis. 9-AYAA microwires with uniform length and thickness were produced after a suspension of (E)-tert-butyl 3-(anthracen-9-yl)acrylate ester 2 microparticles was tumble-mixed in a mixture of phosphoric acid and sodium dodecyl sulfate at 35 °C. The dependence of the results on temperature, surfactant and precursor concentration, and mixing mode was investigated. This chemical reaction-growth method was extended to grow microplates of 9-anthraldehyde 3 using the corresponding acylal 4 as the starting material. Under 475 nm irradiation, the 9-AYAA microwires undergo a photoinduced coiling–uncoiling transition, while the 9-anthraldehyde microplates undergo a folding–unfolding transition.

Keywords: photomechanical, surfactant, organic crystals, uniform

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Authors: Abdullah Al-Nassri, Ahmed Al-Alawi

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Seaweeds are classified into three groups: red, green, and brown. Each group of seaweeds consists of several types that have differences in composition. Even at the species level, there are differences in some ingredients, although in general composition, they are the same. Environmental conditions, availability of nutrients, and maturity stage are the main reasons for composition differences. In this study, two red seaweed species, Melanothamnus somalensis & Gelidium omanense, were collected in September 2021 from Sadh (Dhofar governorate, Oman). Five organic solvents were used sequentially to achieve extraction. The solvents were applied in the following order: hexane, dichloromethane, ethyl acetate, acetone, and methanol. Preparative HPLC (PrepLC) was performed to fraction the extracts. The chemical composition was measured; also, total phenols, flavonoids, and tannins were investigated. The structure of the extracts was analyzed by Fourier-transform infrared spectroscopy (FTIR). Seaweeds demonstrated high differences in terms of chemical composition, total phenolic content (TPC), total flavonoid content (TFC), and total tannin content (TTC). Gelidium omanense showed high moisture content, lipid content and carbohydrates (9.8 ± 0.15 %, 2.29 ± 0.09 % and 70.15 ± 0.42 %, respectively) compared to Melanothamnus somalensis (6.85 ± 0.01 %, 2.05 ± 0.12 % and 52.7 ± 0.36 % respectively). However, Melanothamnus somalensis showed high ash content and protein (27.68 ± 0.40 % and 52.7 ± 0.36 % respectively) compared to Gelidium omanense (8.07 ± 0.39 % and 9.70 ± 0.22 % respectively). Melanothamnus somalensis showed higher elements and minerals content, especially sodium and potassium. This is attributed to the jelly-like structure of Melanothamnus somalensis, which allows storage of more solutes compared to the leafy-like structure of Gelidium omanense. Furthermore, Melanothamnus somalensis had higher TPC in all fractions except the hexane fraction than Gelidium omanense. Except with hexane, TFC in the other solvents’ extracts was significantly different between Gelidium omanense and Melanothamnus somalensis. In all fractions, except dichloromethane and ethyl acetate fractions, there were no significant differences in TTC between Gelidium omanense and Melanothamnus somalensis. FTIR spectra showed variation between fractions, which is an indication of different functional groups.

Keywords: chemical composition, organic extract, Omani seaweeds, biological activity, FTIR

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Authors: V. D. Povolockiy, V. E. Roshchin, Y. Kapelyushin

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Smelting of copper matte is followed by production of a large amount of slag. This slag mostly contains silicates and can be utilized in a construction industry. In addition to silicates it also contains Fe; if the Fe content is high, the density of the silicate phases increases and such a slag cannot be used as an additive for the concrete. Furthermore, slags obtained during copper matte production contain copper, sulphur, zinc and some other elements. Fe is the element with the highest price in these slags. An extraction of Fe is possible even using the conventional methods, e.g., the addition of slag to the charge materials during production of sinter for the blast furnace smelting. However, in this case, the blast furnace hot metal would accumulate sulphur and copper which is very harmful impurity for the steelmaking. An accumulation of copper by the blast furnace hot metal is unacceptable, as copper cannot be removed during further steelmaking operations having a critical effect on the properties of steel. In present work, the technological scheme for non-waste utilization of the copper smelting slags has been suggested and experimentally confirmed. This scheme includes a solid state reduction of Fe and smelting for the separation of cast iron and slag. During solid state reduction, the zinc vapor was trapped. After the reduction and smelting operations, the cast iron containing copper was used for the production of metal balls with increased mechanical properties allowing their utilization for milling of ore minerals. Such a cast iron could also be applied in the production of special types of steel with copper. The silicate slag freed from Fe might be used as a propping agent in the oil industry, or granulated for application as an additive for concrete in a construction industry. Thereby, the suggested products for a Mini Mill plant with non-waste utilization of the copper smelting slags are cast iron grinding balls for the ore minerals, special types of steel with copper, silicate slag utilized as an additive for the concrete and propping agents for the oil industry.

Keywords: utilization of copper slag, cast iron, grinding balls, propping agents

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Authors: Cindy Woods

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After years of implacable neoliberal globalization, multinational corporations have moved from the periphery to the center of the international legal agenda. Human rights advocates have long called for greater corporate accountability in the international arena. The creation of the Global Compact in 2000, while aimed at fostering greater corporate respect for human rights, did not silence these calls. After multiple unsuccessful attempts to adopt a set of norms relating to the human rights responsibilities of transnational corporations, the United Nations succeeded in 2008 with the Guiding Principles on Business and Human Rights (Guiding Principles). The Guiding Principles, praised by some within the international human rights community for their recognition of an individual corporate responsibility to respect human rights, have not escaped their share of criticism. Many view the Guiding Principles to be toothless, failing to directly impose obligations upon corporations, and call for binding international obligations on corporate entities. After decades of attempting to promulgate human rights obligations for multinational corporations, the existing legal frameworks in place fall short of protecting individuals from the human rights abuses of multinational corporations. The Global Compact and Guiding Principles are proof of the United Nations’ unwillingness to impose international legal obligations on corporate actors. In June 2014, the Human Rights Council adopted a resolution to draft international legally binding human rights norms for business entities; however, key players in the international arena have already announced they will not cooperate with such efforts. This Note, through an overview of the existing corporate accountability frameworks and a study of Newmont Mining’s Minas Conga project in Peru, argues that binding international human rights obligations on corporations are necessary to fully protect human rights. Where states refuse to or simply cannot uphold their duty to protect individuals from transnational businesses’ human rights transgressions, there must exist mechanisms to pursue justice directly against the multinational corporation.

Keywords: business and human rights, Latin America, international treaty on business and human rights, mining, human rights

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Authors: Pradeep Lamichhane, Nima Pourali, E. V. Rebrov, Volker Hessel

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Nitrogen fixation is critical for plants for the biosynthesis of protein and nucleic acid. Most of our atmosphere is nitrogen, yet plants cannot directly absorb it from the air, and natural nitrogen fixation is insufficient to meet the demands. This experiment used a fast-modulated surface-confined atmospheric pressure plasma created by a 6 kV (peak-peak) sinusoidal power source with a repetition frequency of 68 kHz to fix nitrogen. Plasmas have been proposed for excitation of nitrogen gas, which quickly oxidised to NOX. With different N2/O2 input ratios, the rate of NOX generation was investigated. The rate of NOX production was shown to be optimal for mixtures of 60–70% O2 with N2. To boost NOX production in plasma, metal oxide catalysts based on TiO2 were coated over the dielectric layer of a reactor. These results demonstrate that nitrogen activation was more advantageous in surface-confined plasma sources because micro-discharges formed on the sharp edges of the electrodes, which is a primary function attributed to NOX synthesis and is further enhanced by metal oxide catalysts. The energy-efficient and sustainable NOX synthesis described in this study will offer a fresh perspective for ongoing research on green nitrogen fixation techniques.

Keywords: nitrogen fixation, fast-modulated, surface-confined, sustainable

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Authors: Sultana Afrin Nipa

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Life on Earth cannot thrive or survive without water. Water is intimately tied with community, culture, spirituality, identity, socio-economic progress, security, self-determination, and livelihood. Thus, access to water is a United Nations recognized human right due to its significance in these realms. However, there is often conflict between those who consider water as the spiritual and cultural value and those who consider it an economic value thus being threatened by economic development, corporate exploitation, government regulation, and increased privatization, highlighting the complex relationship between water and culture. The Colorado River basin is home to over 29 federally recognized tribal nations. To these tribes, it holds cultural, economic, and spiritual significance and often extends to deep human-to-non-human connections frequently precluded by the Westphalian regulations and settler laws. Despite the recognition of access to rivers as a fundamental human right by the United Nations, tribal communities and their water rights have been historically disregarded through inter alia, colonization, and dispossession of their resources. Law of the River such as ‘Winter’s Doctrine’, ‘Bureau of Reclamation (BOR)’ and ‘Colorado River Compact’ have shaped the water governance among the shareholders. However, tribal communities have been systematically excluded from these key agreements. While the Winter’s Doctrine acknowledged that tribes have the right to withdraw water from the rivers that pass through their reservations for self-sufficiency, the establishment of the BOR led to the construction of dams without tribal consultation, denying the ‘Winters’ regulation and violating these rights. The Colorado River Compact, which granted only 20% of the water to the tribes, diminishes the significance of international legal frameworks that prioritize indigenous self-determination and free pursuit of socio-economic and cultural development. Denial of this basic water right is the denial of the ‘recognition’ of their sovereignty and self-determination that questions the effectiveness of the international law. This review assesses the international legal frameworks concerning indigenous rights and water justice and aims to pinpoint gaps hindering the effective recognition and protection of Indigenous water rights in Colorado River Basin. This study draws on a combination of historical and qualitative data sets. The historical data encompasses the case settlements provided by the Bureau of Reclamation (BOR) respectively the notable cases of Native American water rights settlements on lower Colorado basin related to Arizona from 1979-2008. This material serves to substantiate the context of promises made to the Indigenous people and establishes connections between existing entities. The qualitative data consists of the observation of recorded meetings of the Central Arizona Project (CAP) to evaluate how the previously made promises are reflected now. The study finds a significant inconsistency in participation in the decision-making process and the lack of representation of Native American tribes in water resource management discussions. It highlights the ongoing challenges faced by the indigenous people to achieve their self-determination goal despite the legal arrangements.

Keywords: colorado river, indigenous rights, law of the river, water governance, water justice

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Authors: Chatkaew Tansakul, Saovajit Nanruksa, Surasak Chonchirdsin

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Heavy metals in the environment can be occurred by both natural weathering process and human activity, which may present significant risks to human health and the wider environment. A number of heavy metals, i.e. Arsenic (As) and Manganese (Mn), are found with a relatively high concentration in the northern part of Thailand that was assumptively from natural parent rocks and materials. However, scarce literature is challenging to identify the accurate root cause and best available explanation. This study is, therefore, aim to gather heavy metals data in 5 provinces of the North of Thailand where PTT Exploration and Production (PTTEP) public company limited has operated for more than 20 years. A thousand heavy metal analysis is collected and interpreted in term of Enrichment Factor (EF). The trend and distribution of heavy metals in soil and sediment are analyzed by considering altogether the geochemistry of the regional soil and rock. . In addition, the relationship between land use and heavy metals distribution is investigated. In the first conclusion, heavy metal concentrations of (As) and (Mn) in the studied areas are equal to 7.0 and 588.6 ppm, respectively, which are comparable to those in regional parent materials (1 – 12 and 850 – 1,000 ppm for As and Mn respectively). Moreover, there is an insignificant escalation of the heavy metals in these studied areas over two decades.

Keywords: contaminated soil, enrichment factor, heavy metals, parent materials in North of Thailand

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Authors: Nayab Kanwal, Noor Us Saher

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The management and utilization of food resources is becoming a big issue due to rapid urbanization, wastage and non-sustainable use of food, especially in developing countries. Therefore, the use of seafood as alternative sources is strongly promoted worldwide. Marine pollution strongly affects marine organisms, which ultimately decreases their export quality. The monitoring of contamination in marine organisms is a good indicator of the environmental quality as well as seafood quality. Monitoring the accumulation of chemical elements within various tissues of organisms has become a useful tool to survey current or chronic levels of heavy metal exposure within an environment. In this perspective, this study was carried out to compare the previous and current levels (Year 2012 and 2014) of heavy metals (Cd, Pb, Cr, Cu and Zn) in crabs marketed in Karachi and to estimate the toxicological risk associated with their intake. The accumulation of metals in marine organisms, both essential (Cu and Zn) and toxic (Pb, Cd and Cr), natural and anthropogenic, is an actual food safety issue. Significant (p>0.05) variations in metal concentrations were found in all crab species between the two years, with most of the metals showing high accumulation in 2012. For toxicological risk assessment, EWI (Estimated weekly intake), Target Hazard quotient (THQ) and cancer risk (CR) were also assessed and high EWI, Non- cancer risk (THQ < 1) showed that there is no serious threat associated with the consumption of shellfish species on Karachi coast. The Cancer risk showed the highest risk from Cd and Pb pollution if consumed in excess. We summarize key environmental health research on health effects associated with exposure to contaminated seafood. It could be concluded that considering the Pakistan coast, these edible species may be sensitive and vulnerable to the adverse effects of environmental contaminants; more attention should be paid to the Pb and Cd metal bioaccumulation and to toxicological risks to seafood and consumers.

Keywords: cancer risk, edible crabs, heavy metals pollution, risk assessment

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Authors: Michael A. Sprayberry, Vincent C. Paquit

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Process parameter optimization in metal powder bed electron beam melting (MPBEBM) is crucial to ensure the technology's repeatability, control, and industry-continued adoption. Despite continued efforts to address the challenges via the traditional design of experiments and process mapping techniques, there needs to be more successful in an on-the-fly optimization framework that can be adapted to MPBEBM systems. Additionally, data-intensive physics-based modeling and simulation methods are difficult to support by a metal AM alloy or system due to cost restrictions. To mitigate the challenge of resource-intensive experiments and models, this paper introduces a Multi-Objective Reinforcement Learning (MORL) methodology defined as an optimization problem for MPBEBM. An off-policy MORL framework based on policy gradient is proposed to discover optimal sets of beam power (P) – beam velocity (v) combinations to maintain a steady-state melt pool depth and phase transformation. For this, an experimentally validated Eagar-Tsai melt pool model is used to simulate the MPBEBM environment, where the beam acts as the agent across the P – v space to maximize returns for the uncertain powder bed environment producing a melt pool and phase transformation closer to the optimum. The culmination of the training process yields a set of process parameters {power, speed, hatch spacing, layer depth, and preheat} where the state (P,v) with the highest returns corresponds to a refined process parameter mapping. The resultant objects and mapping of returns to the P-v space show convergence with experimental observations. The framework, therefore, provides a model-free multi-objective approach to discovery without the need for trial-and-error experiments.

Keywords: additive manufacturing, metal powder bed fusion, reinforcement learning, process parameter optimization

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Authors: Doo W. Lee, Soo J. Lee, Bye R. Yoon, Jae Y. Jho, Kyehan Rhee

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Hand exoskeletons have been developed in order to assist daily activities for disabled and elder people. A figure exoskeleton was developed using ionic polymer metal composite (IPMC) actuators, and the performance of it was evaluated in this study. In order to study dynamic performance of a finger dummy performing pinching motion, force generating characteristics of an IPMC actuator and pinching motion of a thumb and index finger dummy actuated by IMPC actuators were analyzed. The blocking force of 1.54 N was achieved under 4 V of DC. A thumb and index finger dummy, which has one degree of freedom at the proximal joint of each figure, was manufactured by a three dimensional rapid prototyping. Each figure was actuated by an IPMC actuator, and the maximum fingertip force was 1.18 N. Pinching motion of a dummy was analyzed by two video cameras in vertical top and horizontal left end view planes. A figure dummy powered by IPMC actuators could perform flexion and extension motion of an index figure and a thumb.

Keywords: finger exoskeleton, ionic polymer metal composite, flexion and extension, motion analysis

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Authors: Leo Paul Vaurs, Sonia Heaven, Charles Banks

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Municipal solid waste (MSW) is a virtually unlimited source of lignocellulosic material in the form of a waste paper/cardboard mixture which can be converted into fermentable sugars via cellulolytic enzyme hydrolysis in a biorefinery. The extraction of the lignocellulosic fraction and its preparation, however, are energy and water demanding processes. The waste water generated is a rich organic liquor with a high Chemical Oxygen Demand that can be partially cleaned while generating biogas in an Upflow Anaerobic Sludge Blanket bioreactor and be further re-used in the process. In this work, an experiment was designed to determine the critical contaminant concentrations in water affecting either anaerobic digestion or enzymatic hydrolysis by simulating multiple water re-circulations. It was found that re-using more than 16.5 times the same water could decrease the hydrolysis yield by up to 65 % and led to a complete granules desegregation. Due to the complexity of the water stream, the contaminant(s) responsible for the performance decrease could not be identified but it was suspected to be caused by sodium, potassium, lipid accumulation for the anaerobic digestion (AD) process and heavy metal build-up for enzymatic hydrolysis. The experimental data were incorporated into a Water Pinch technology based model that was used to optimize the water re-utilization in the modelled system to reduce fresh water requirement and wastewater generation while ensuring all processes performed at optimal level. Multiple scenarios were modelled in which sub-process requirements were evaluated in term of importance, operational costs and impact on the CAPEX. The best compromise between water usage, AD and enzymatic hydrolysis yield was determined for each assumed contaminant degradations by anaerobic granules. Results from the model will be used to build the first MSW based biorefinery in the USA.

Keywords: anaerobic digestion, enzymatic hydrolysis, municipal solid waste, water optimization

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Authors: Lucky Malise, Hilary Rutto, Tumisang Seodigeng

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Heavy metal contamination in waste water is a very serious issue affecting a lot of industrialized countries due to the health and environmental impact of these heavy metals on human life and the ecosystem. Adsorption using activated carbon is the most promising method for the removal of heavy metals from waste water but commercial activated carbon is expensive which gives rise to the need for alternatively activated carbon derived from cheap precursors, agricultural wastes, or byproducts from other processes. In this study activated bio-carbon derived from the carbonaceous material obtained from the pyrolysis of Marula nut shells was chemically activated and used as an adsorbent for the removal of lead (II) and copper (II) ions from aqueous solution. The surface morphology and chemistry of the adsorbent before and after chemical activation with zinc chloride impregnation were studied using SEM and FTIR analysis respectively and the results obtained indicate that chemical activation with zinc chloride improves the surface morphology of the adsorbent and enhances the intensity of the surface oxygen complexes on the surface of the adsorbent. The effect of process parameters such as adsorbent dosage, pH value of the solution, initial metal concentration, contact time, and temperature on the adsorption of lead (II) and copper (II) ions onto Marula nut activated carbon were investigated, and their optimum operating conditions were also determined. The experimental data was fitted to both the Langmuir and Freundlich isotherm models, and the data fitted best on the Freundlich isotherm model for both metal ions. The adsorption kinetics were also evaluated, and the experimental data fitted the pseudo-first order kinetic model better than the pseudo second-order kinetic model. The adsorption thermodynamics were also studied and the results indicate that the adsorption of lead and copper ions is spontaneous and exothermic in nature, feasible, and also involves a dissociative mechanism in the temperature range of 25-45 °C.

Keywords: adsorption, isotherms, kinetics, marula nut shells activated carbon, thermodynamics

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Authors: Bipul Behari Saha, Sunil Kumar Singh, P. Padmaja, Kamlesh Vishwakarma

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Dissipation study of tebuconazole in alluvial, black and deep-black clayey soils collected from paddy, mango and peanut cropland of tropical agro-climatic zone of India at three concentration levels were carried out for monitoring the water contamination through persisted residual toxicity. The soil-slurry samples were analyzed by capillary GC-NPD methods followed by ultrasound-assisted extraction (UAE) technique and cleanup process. An excellent linear relationship between peak area and concentration obtained in the range 1 to 50 μgkg-1. The detection (S/N, 3 ± 0.5) and quantification (S/N, 7.5 ± 2.5) limits were 3 and 10 μgkg-1 respectively. Well spiked recoveries were achieved from 96.28 to 99.33 % at levels 5 and 20 μgkg-1 and method precision (% RSD) was ≤ 5%. The soils dissipation of tebuconazole was fitted in first order kinetic-model with half-life between 34.48 to 48.13 days. The soil organic-carbon (SOC) content correlated well with the dissipation rate constants (DRC) of the fungicide Tebuconazole. An increase in the SOC content resulted in faster dissipation. The results indicate that the soil organic carbon and tebuconazole concentrations plays dominant role in dissipation processes. The initial concentration illustrated that the degradation rate of tebuconazole in soils was concentration dependent.

Keywords: cropland soil, dissipation, laboratory incubation, tebuconazole

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Authors: Esraa Mohamed El-Fawal

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A facile solvothermal procedure was applied to fabricate zinc ferrite nanoparticles (ZnFe₂O₄ NPs). Activated carbon (AC) derived from peanut shells is synthesized using a microwave through the chemical activation method. The ZnFe₂O₄-AC composite is then mixed with a cerium-based metal-organic framework (CeMOF) by solid-state adding to formulate ZnFe₂O₄-AC/CeMOF composite. The synthesized photo materials were tested by scanning/transmission electron microscope (SEM/TEM), Photoluminescence (PL), (XRD) X-Ray diffraction, (FTIR) Fourier transform infrared, (UV-Vis/DRS) ultraviolet-visible/diffuse reflectance spectroscopy. The prepared ZnFe₂O₄-AC/CeMOFphotomaterial shows significantly boosted efficiency for photodegradation of methyl orange /methylene blue (MO/MB) compared with the pristine ZnFe₂O₄ and ZnFe₂O₄-AC composite under the irradiation of visible-light. The favorable ZnFe₂O₄-AC/CeMOFphotocatalyst displays the highest photocatalytic degradation efficiency of MB/MO (R: 91.5-88.6%, consecutively) compared with the other as-prepared materials after 30 min of visible-light irradiation. The apparent reaction rate K: 1.94-1.31 min-1 is also calculated. The boosted photocatalytic proficiency is ascribed to the heterojunction at the interface of prepared photo material that assists the separation of the charge carriers. To reach optimization, statistical analysis using response surface methodology was applied. The effect of independent parameters (such as A (pH), B (irradiation time), and (c) initial pollutants concentration on the response function (%)photodegradation of MB/MO dyes (as examples of azodyes) was investigated via using central composite design. At the optimum condition, the photodegradation efficiency (%) of the MB/MO is 99.8-97.8%, respectively. ZnFe2O₄-AC/CeMOF hybrid reveals good stability over four consecutive cycles.

Keywords: azo-dyes, photo-catalysis, zinc ferrite, response surface methodology

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Authors: Pelin Yılmaz Çetiner, Metin Mert İlgün, Nazlı Çetindağ, Emine Birci, Gizemnur Yıldız Uysal, Özcan Hatipoğlu, Ehsan Tuzcuoğlu, Gökhan Sır

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Water scarcity is an inevitable problem affecting more and more people day by day. It is a worldwide crisis and a consequence of rapid population growth, urbanization and overexploitation. Thus, the solutions providing the reclamation of the wastewater are the desired approach. Wastewater contains various substances such as organic, soaps and detergents, solvents, biological substances, and inorganic substances. The physical properties of the wastewater differs regarding to its origin such as commerical, domestic or hospital usage. Thus, the treatment strategy of this type of wastewater is should be comprehensively investigated and properly treated. The advanced oxidation process comes up as a hopeful method associated with the formation of reactive hydroxyl radicals that are highly reactive to oxidize of organic pollutants. This process has a priority on other methods such as coagulation, flocuation, sedimentation and filtration since it was not cause any undesirable by-products. In the present study, it was aimed to investigate the applicability of advanced oxidation process for the treatment of household appliances wastewater. For this purpose, the laboratory studies providing the effectively addressing of the formed radicals to organic pollutants were carried out. Then the effect of process parameters were comprehensively studied by using response surface methodology, Box-Benhken experimental desing. The final chemical oxygen demand (COD) was the main output to evaluate the optimum point providing the expected COD removal. The linear alkyl benzene sulfonate (LAS), total dissolved solids (TDS) and color were measured for the optimum point providing the expected COD removal. Finally, present study pointed out that advanced oxidation process might be efficiently preffered to treat of the household appliances wastewater and the optimum process parameters provided that expected removal of COD.

Keywords: advanced oxidation process, household appliances wastewater, modelling, water reuse

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Authors: Nelson Nenuwe

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The behavior of interacting electrons in one dimension was studied by calculating correlation functions and critical exponents at zero and external magnetic fields for arbitrary band filling. The technique employed in this study is based on the conformal field theory (CFT). The charge and spin degrees of freedom are separated, and described by two independent conformal theories. A detailed comparison of the t-J model with the repulsive Hubbard model was then undertaken with emphasis on their Tomonaga-Luttinger (TL) liquid properties. Near half-filling the exponents of the t-J model take the values of the strong-correlation limit of the Hubbard model, and in the low-density limit the exponents are those of a non-interacting system. The critical exponents obtained in this study belong to the repulsive TL liquid (conducting phase) and attractive TL liquid (superconducting phase). The theoretical results from this study find applications in one-dimensional organic conductors (TTF-TCNQ), organic superconductors (Bechgaard salts) and carbon nanotubes (SWCNTs, DWCNTs and MWCNTs). For instance, the critical exponent at from this study is consistent with the experimental result from optical and photoemission evidence of TL liquid in one-dimensional metallic Bechgaard salt- (TMTSF)2PF6.

Keywords: critical exponents, conformal field theory, Hubbard model, t-J model

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Authors: Farzaneh Fakheri Raof, Abdolkhalegh vadian

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One of the most important environmental issues in developing countries is municipal solid waste management. In this context, knowledge of the quantity and composition of solid waste provides the basic information for the optimal management of solid waste. Many studies have been conducted to investigate the impact of economic, social and cultural factors on generation trend of solid waste, however, few of these have addressed the role of religion in the matter. The present study is a field investigation on generation trend of solid waste in Mashhad, a metropolitan city in northeastern Iran. Accordingly, the religious rituals, quantity and composition of municipal solid waste were considered as independent and dependent variables, respectively. For this purpose, the quantity of the solid waste was initially determined. Afterwards, they were classified into 12 groups using the relevant standard methods. The results showed that the production rate of the municipal solid waste was 1,507 tons per day. Composing 65.2% of the whole; the organic materials constitute the largest share of the total municipal solid waste in Mashhad. The obtained results also revealed that there is a positive relationship between waste generation and the months of religious ceremonies so that the greatest amount of waste generated in the city was reported from Ramadan (as a religious month) in a way that it was significantly different from other months.

Keywords: Mashhad, municipal solid waste, religious months, waste composition, organic waste

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Authors: Kiurski S. Jelena, Ranogajec G. Jonjaua, Oros B. Ivana, Kecić S. Vesna

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The adsorption efficiency of fired clayey pellets of 5 and 8 mm diameter size for Cu(II) and Zn(II) ions removal from a waste printing developer was studied. In order to investigate the influence of contact time, adsorbent mass and pellet size on the adsorption efficiency the batch mode was carried out. Faster uptake of copper ions was obtained with the fired clay pellets of 5 mm diameter size within 30 minutes. The pellets of 8 mm diameter size showed the higher equilibrium time (60 to 75 minutes) for copper and zinc ions. The results pointed out that adsorption efficiency increases with the increase of adsorbent mass. The maximal efficiency is different for Cu(II) and Zn(II) ions due to the pellet size. Therefore, the fired clay pellets of 5 mm diameter size present an effective adsorbent for Cu(II) ions removal (adsorption efficiency is 63.6%), whereas the fired clay pellets of 8 mm diameter size are the best alternative for Zn(II) ions removal (adsorption efficiency is 92.8%) from a waste printing developer.

Keywords: adsorption efficiency, clayey pellet, metal ions, waste printing developer

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Authors: Yu. Mateyshina, A. Ulihin, N. Uvarov

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Supercapacitors are one of the most promising devices for energy storage applications as they can provide higher power density than batteries and higher energy density than conventional dielectric capacitors. Carbon materials with various microtextures are considered as main candidates for supercapacitors in terms of high surface area, interconnected pore structure, controlled pore size, high electrical conductivity and environmental friendliness. The specific capacitance (C) of the electrode material of the Electrochemical Double Layer Capacitors (EDLC) is known to depend on the specific surface area (Ss) and the pore structure. Activated carbons are most commonly used in supercapacitors because of their high surface area (Ss ≥ 1000 m2/g), good adhesion to electrolytes and low cost. In this work, electrochemical properties of new microporous and mesoporous carbon electrode materials were studied. The aim of the work was to investigate the relationship between the specific capacitance and specific surface area in a series of materials prepared from different organic precursors.. As supporting matrixes different carbon samples with Ss = 100-2000 m2/g were used. The materials were modified by treatment in acids (H2SO4, HNO3, acetic acid) in order to enable surface hydrophilicity. Then nanoparticles of transition metal oxides (for example NiO) were deposited on the carbon surfaces using methods of salts impregnation, mechanical treatment in ball mills and the precursors decomposition. The electrochemical characteristics of electrode hybrid materials were investigated in a symmetrical two-electrode cell using an impedance spectroscopy, voltammetry in both potentiodynamic and galvanostatic modes. It was shown that the value of C for the materials under study strongly depended on the preparation method of the electrode and the type of electrolyte (1 M H2SO4, 6 M KOH, 1 M LiClO4 in acetonitryl). Specific capacity may be increased by the introduction of nanoparticles from 50-100 F/g for initial carbon materials to 150-300 F/g for nanocomposites which may be used in supercapacitors. The work is supported by the по SC-14.604.21.0013.

Keywords: supercapacitors, carbon electrode, mesoporous carbon, electrochemistry

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Authors: Navven Desai, Veena Soraganvi

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Heavy metals such as lead, cadmium and mercury do not have biological significance hence they are known to be extremely toxic heavy metals. Water contains various heavy metals like Cadmium (Cd), Chromium (Cr), Copper (Cu), Nickel (Ni), Arsenic (As), Lead (Pb), and Zinc (Zn) etc., when it gets polluted with industrial waste water. These heavy metals cause various health effects even at low concentration when consumed by humans. Most of the heavy metals are poisonous to living organisms. Heavy metals are non-degradable and are preserved in the environment through bioaccumulation. Therefore removal of heavy metals from water is necessary. In recent years, a great deal of attentions has been focused on to the application of nanosized metal oxides to treat heavy metals, especially titanium oxides, ferric oxides, manganese oxides, aluminium oxides and magnesium oxides as adsorbent and photocatalyst. TiO2 based photocatalysts have attracted continuously increasing attention because of the excellent properties such as high light -conversion efficiency, chemical stability, nontoxic nature, low cost. The catalyst displays high photocatalytic activity because of its large surface area. In this study, the photocatalytic degradation of Lead (Pb) from aqueous solution was investigated in natural sunlight by using TiO2 as Nanomaterial. This study was performed at laboratory scale. All the experiments were carried out in the batch process. The concentration of lead was constant (25mg/lit) in the experiment and effect of titanium dioxide dose and pH were varied to study the removal efficiency of the lead by adsorption. Further study was performed on the dependence of photocatalytic reaction on the reaction temperature. The aqueous solution was prepared by Lead metal powder. TiO2 photo catalyst nanopowder used was Sisco-74629 grade. The heavy metal is analyzed with VARIAN AA 240 atomic adsorption spectrophotometer. The study shows, with increasing TiO2 dose and pH the lead removal increases. According to study, it can be concluded that the utilization of titanium dioxide accounted for higher efficiency in the removal of lead from aqueous solution.

Keywords: adsorption, heavy metals, nanomaterial, photocatalysis

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Authors: Shepherd Manhokwe, Sheron Shoko, Cuthbert Zvidzai

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In the present study, the interactive effects of temperature and cultured bacteria on the performance of a biological treatment system of yeast processing wastewater were investigated. The main objective of this study was to investigate and optimize the operating parameters that reduce organic load and colour. Experiments were conducted based on a Central Composite Design (CCD) and analysed using Response Surface Methodology (RSM). Three dependent parameters were either directly measured or calculated as response. These parameters were total Chemical Oxygen Demand (COD) removal, colour reduction and total solids. COD removal efficiency of 26 % and decolourization efficiency of 44 % were recorded for the wastewater treatment. The optimized conditions for the biological treatment were found to be at 20 g/l cultured bacteria and 25 °C for COD reduction. For colour reduction optimum conditions were temperature of 30.35°C and bacterial formulation of 20g/l. Biological treatment of baker’s yeast processing effluent is a suitable process for the removal of organic load and colour from wastewater, especially when the operating parameters are optimized.

Keywords: COD reduction, optimisation, response surface methodology, yeast processing wastewater

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Authors: Kageeporn Wongpreedee, Bongkot Phichaikamjornwut, Duangkhae Bootkul

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The technique of stone in place casting had been established in jewelry production for two decades. However, the process were not widely used since it was limited to precious stones with high hardness and high stabililty at high temperature. This experiment were tested on tourmaline which is semi-precious gemstone having less hardness and less stability comparing to precious stones. The experiment were designed into two parts. The first part is to understand the phenomena of tourmaline under the heating conditions. Natural tourmaline stones were investigated and compared inclusions inside stones tested at temperature of 500 °C, 600 °C, and 700 °C. The second part is to cast the treated tourmaline with ion-implanation under the stones in place casting conditions. The results showed that stones were able to tolerate as much as at 700 °C showing the growths of inclusions inside the stones. The second part of this experiment were compared tourmaline with ion-implantation and natural tourmaline using on stones in place casting process at different stone setting types. The results showed that the cracks and inclustions of both treat and natural tourmaline with stones in place casting were propagate due to high stress of metal contractions. The stones with ion-implatation were more likely tolerate to cracks and inclusion propagations inside the stones.

Keywords: stone in place casting, tourmaline, ion implantation, metal contraction

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Authors: Lin Gong, Holger Göbel

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In the present study, we have investigated the influence of UV/ozone treatment on pentacene-based organic field effect transistors (OFETs) with a bilayer gate dielectric. The OFETs for this study were fabricated on heavily n-doped Si substrates with a thermally deposited SiO2 dielectric layer (300nm). On the SiO2 dielectric a very thin (≈ 15nm) buffer layer of polystyrene (PS) was first spin-coated and then treated by UV/ozone to modify the surface prior to the deposition of pentacene. We found out that by extending the UV/ozone treatment time the threshold voltage of the OFETs was monotonically shifted towards positive values, whereas the field effect mobility first decreased but eventually reached a stable value after a treatment time of approximately thirty seconds. Since the field effect mobility of the UV/ozone treated bilayer OFETs was found to be higher than the value of a comparable transistor with a single layer dielectric, we propose that the bilayer (SiO2/PS) structure can be used to shift the threshold voltage to a desired value without sacrificing field effect mobility.

Keywords: buffer layer, organic field effect transistors, threshold voltage, UV/ozone treatment

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Authors: Eun-Young Yoon

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The purpose of this research is to examine how unification with North Korea is being taught in South Korea classrooms. To analysis of the curriculum and textbooks about unification in South Korean classroom, this study uses nationalism and multiculturalism as major theoretical frameworks. Major findings show that curriculum and textbooks should describe unification with North Korea more detailed and complicated. And the balancing between ‘global citizenship’ and ‘national identity’ is needed.

Keywords: global citizenship, multiculturalism, nationalism, unification education

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Authors: Oluwasanmi Teniola, Abraham Adeleke, Ademola Ibitoye, Moshood Shitu

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To establish an economical and efficient process for the recovery of gold metal from refractory gold ore obtained from Esperando axis of Osun state Nigeria, the adsorption of gold (III) from aqua reqia leached solution of the ore using bagasse nanoparticles has been studied under various experimental variables using batch technique. The extraction percentage of gold (III) on the prepared bagasse nanoparticles was determined from its distribution coefficients as a function of solution pH, contact time, adsorbent, adsorbate concentrations, and temperature. The rate of adsorption of gold (III) on the prepared bagasse nanoparticles is dependent on pH, metal concentration, amount of adsorbate, stirring rate, and temperature. The adsorption data obtained fit into the Langmuir and Freundlich equations. Three different temperatures were used to determine the thermodynamic parameters of the adsorption of gold (III) on bagasse nanoparticles. The heat of adsorption was measured to be a positive value ΔHo = +51.23kJ/mol, which serves as an indication that the adsorption of gold (III) on bagasse nanoparticles is endothermic. Also, the negative value of ΔGo = -0.6205 kJ/mol at 318K shows the spontaneity of the process. As the temperature was increased, the value of ΔGo becomes more negative, indicating that an increase in temperature favors the adsorption process. With the application of optimal adsorption variables, the adsorption capacity of gold was 0.78 mg/g of the adsorbent, out of which 0.70 mg of gold was desorbed with 0.1 % thiourea solution.

Keywords: adsorption, bagasse, extraction, nanoparticles, recovery

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Authors: Nicholas Sehube, Rosemary Kelebemang, Pogisego Dinake

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The extent of Pb contamination of shooting range soils has never been ascertained in Botswana, this was the first attempt in evaluating the deposition of Pb into the soils emanating from munitions. A total of 8 military shooting ranges were used for this study. Soil samples were collected at each of the 8 shooting ranges at the berm (stop butt), target line, 50 and 100 m from the berm. In all of the shooting ranges investigated the highest concentrations were found in the berm soils. The highest Pb concentrations of 38 406.87 mg/Kg were found in the berm soils of Thebephatshwa shooting range which is enclosed within a military camp with staff residential dwelling only a kilometre away. Most of the shooting ranges soils contained elevated levels of Pb in the ranges above 2000 mg/kg far exceeding the United States Environmental Protection Agency (USEPA) critical value of 400 mg/Kg. Mobilization of lead at high pH is attributed to low organic matter and such was the case with Thebephatshwa shooting range with a percept organic matter of 0.35±0.08. The predominant weathering products in these shooting ranges were cerussite (PbCO3), hydrocerussite (Pb(CO3)2(OH)2 and massicot (PbO). The detailed examination and characterization of the extent of pollution will help in the development and implementation of scientifically sound remediation and restoration of shooting ranges soils.

Keywords: ammunition, Botswana, Pb, pollution, soil

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Authors: Efe Gumuslu, Guclu Insel, Gülten Yuksek, Nilay Sayi Ucar, Emine Ubay Cokgor, Tuğba Olmez Hanci, Didem Okutman Tas, Fatoş Germirli Babuna, Derya Firat Ertem, Ökmen Yildirim, Özge Erturan, Betül Kirci

Abstract:

Although water reclamation and reuse are inseparable parts of sustainable production concept all around the world, current levels of reuse constitute only a small fraction of the total volume of industrial effluents. Nowadays, within the perspective of serious climate change, wastewater reclamation and reuse practices should be considered as a requirement. Industrial sector is one of the largest users of water sources. The OECD Environmental Outlook to 2050 predicts that global water demand for manufacturing will increase by 400% from 2000 to 2050 which is much larger than any other sector. Metal finishing industry is one of the industries that requires high amount of water during the manufacturing. Therefore, actions regarding the improvement of wastewater treatment and reuse should be undertaken on both economic and environmental sustainability grounds. Process wastewater can be reused for more purposes if the appropriate treatment systems are installed to treat the wastewater to the required quality level. Recent studies showed that membrane separation techniques may help in solving the problem of attaining a suitable quality of water that allows being recycled back to the process. The metal finishing factory where this study is conducted is one of the biggest white-goods manufacturers in Turkey. The sheet metal parts used in the cookers production have to be exposed to surface pre-treatment processes composed of degreasing, rinsing, nanoceramics coating and deionization rinsing processes, consecutively. The wastewater generating processes in the factory are enamel coating, painting and styrofoam processes. In the factory, the main source of water is the well water. While some part of the well water is directly used in the processes after passing through resin treatment, some portion of it is directed to the reverse osmosis treatment to obtain required water quality for enamel coating and painting processes. In addition to these processes another important source of water that can be considered as a potential water source is rainwater (3660 tons/year). In this study, process profiles as well as pollution profiles were assessed by a detailed quantitative and qualitative characterization of the wastewater sources generated in the factory. Based on the preliminary results the main water sources that can be considered for reuse in the processes were determined as painting and styrofoam processes.

Keywords: enamel coating, painting, reuse, wastewater

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Authors: Vishnu V. Pillai, Sunil P. Lonkar, Akhil M. Abraham, Saeed M. Alhassan

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An effectual technology for wastewater treatment is a great demand now in order to encounter the water pollution caused by organic pollutants. Photocatalytic oxidation technology is widely used in removal of such unsafe contaminants. Among the semi-conducting metal oxides, robust and thermally stable TiO2 has emerged as a fascinating material for photocatalysis. Enhanced catalytic activity was observed for nanostructured TiO2 due to its higher surface, chemical stability and higher oxidation ability. However, higher charge carrier recombination and wide band gap of TiO2 limits its use as a photocatalyst in the UV region. It is desirable to develop a photocatalyst that can efficiently absorb the visible light, which occupies the main part of the solar spectrum. Hence, in order to extend its photocatalytic efficiency under visible light, TiO2 nanoparticles are often doped with metallic or non-metallic elements. Non-metallic doping of TiO2 has attracted much attention due to the low thermal stability and enhanced recombination of charge carriers endowed by metallic doping of TiO2. Amongst, sulfur doped TiO2 is most widely used photocatalyst in environmental purification. However, the most of S-TiO2 synthesis technique uses toxic chemicals and complex procedures. Hence, a facile, scalable and environmentally benign preparation process for S-TiO2 is highly desirable. In present work, we have demonstrated new and facile solid-state reaction method for S-TiO2 synthesis that uses abundant elemental sulfur as S source and moderate temperatures. The resulting nano-sized S-TiO2 has been successfully employed as visible light photocatalyst in methylene blue dye removal from aqueous media.

Keywords: ecofriendly, nanomaterials, methylene blue, photocatalysts

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Authors: Silviya Todorova, Anton Naydenov, Ralitsa Velinova, Alexander Larin

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Catalytic combustion of methane has been extensively investigated for emission control and power generation during the last decades. The alumina-supported palladium catalyst is widely accepted as the most active catalysts for catalytic combustion of methane. The activity of Pd/Al₂O₃ decreases during the time on stream, especially underwater vapor. The following order of activity in the reaction of complete oxidation of methane was established: Co₃O₄> CuO>NiO> Mn₂O₃> Cr₂O₃. It may be expected that the combination between Pd and these oxides could lead to the promising catalysts in the reaction of complete methane. In the present work, we investigate the activity of Pd/Al₂O₃ catalysts promoted with other metal oxides (MOx; M= Ni, Co, Ce). The Pd-based catalysts modified by metal oxide were prepared by sequential impregnation of Al₂O₃ with aqueous solutions of Me(NO₃)₂.6H₂O and Pd(NO₃)₂H₂O. All samples were characterized by X-ray diffraction (XRD), temperature-programmed reduction (TPR), and X-ray photoelectron spectroscopy (XPS). An improvement of activity was observed after modification with different oxides. The results demonstrate that the Pd/Al₂O₃ catalysts modified with Co and Ce by impregnation with a common solution of respective salts, exhibit the most promising catalytic activity for methane oxidation. Most probably, the presence of Co₃O₄ and CeO₂ on catalytic surface increases surface oxygen and therefore leads to the better reactivity in methane combustion.

Keywords: methane combustion, palladium, Co-Ce, Ni-Ce

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