Search results for: atmospheric carbon dioxide

Authors: Atilla Evcin, Bahri Ersoy, Süleyman Akpınar, I. Sinan Atlı

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Ceramic, polymer and composite nanofibers are nowadays begun to be utilized in many fields of nanotechnology. By the means of dimensions, these fibers are as small as nano scale but because of having large surface area and microstructural characteristics, they provide unique mechanic, optical, magnetic, electronic and chemical properties. In terms of nanofiber production, electrospinning has been the most widely used technique in recent years. In this study, carbon nanofibers have been synthesized from solutions of Polyacrylonitrile (PAN)/ N,N-dimethylformamide (DMF) by electrospinning method. The carbon nanofibers have been stabilized by oxidation at 250 °C for 2 h in air and carbonized at 750 °C for 1 h in H2/N2. Images of carbon nanofibers have been taken with scanning electron microscopy (SEM). The images have been analyzed to study the fiber morphology and to determine the distribution of the fiber diameter using FibraQuant 1.3 software. Then polymer composites have been produced from mixture of carbon nanofibers and silicone polymer. The final polymer composites have been characterized by X-ray diffraction method and scanning electron microscopy (SEM) energy dispersive X-ray (EDX) measurements. These results have been reported and discussed. At result, homogeneous carbon nanofibers with 100-167 nm of diameter were obtained with optimized electrospinning conditions.

Keywords: electrospinning, characterization, composites, nanofiber

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Authors: Mojo Mengistu Gelasso

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The tropical forest is considered the most important forest ecosystem for mitigating climate change by sequestering a high amount of carbon. The potential carbon stock of the forest can be influenced by many factors. Therefore, studying these factors is crucial for understanding the determinants that affect the potential for woody carbon storage in the forest. This study was conducted to evaluate the potential for woody carbon stock and how it varies based on plant community types, as well as along altitudinal, slope, and aspect gradients in the Munessa dry Afromontane forest. Vegetation data was collected using systematic sampling. Five line transects were established at 100 m intervals along the altitudinal gradient between two consecutive transect lines. On each transect, 10 quadrats (20 x 20 m), separated by 200 m, were established. The woody carbon was estimated using an appropriate allometric equation formulated for tropical forests. The data was analyzed using one-way ANOVA in R software. The results showed that the total woody carbon stock of the Munessa forest was 210.43 ton/ha. The analysis of variance revealed that woody carbon density varied significantly based on environmental factors, while community types had no significant effect. The highest mean carbon stock was found at middle altitudes (2367-2533 m.a.s.l), lower slopes (0-13%), and west-facing aspects. The Podocarpus falcatus-Croton macrostachyus community type also contributed a higher woody carbon stock, as larger tree size classes and older trees dominated it. Overall, the potential for woody carbon sequestration in this study was strongly associated with environmental variables. Additionally, the uneven distribution of species with larger diameter at breast height (DBH) in the study area might be linked to anthropogenic factors, as the current forest growth indicates characteristics of a secondary forest. Therefore, our study suggests that the development and implementation of a sustainable forest management plan is necessary to increase the carbon sequestration potential of this forest and mitigate climate change.

Keywords: munessa forest, woody carbon stock, environmental factors, climate mitigation

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Authors: Mengistu Gelasso Mojo

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The tropical forest is considered the most important forest ecosystem for mitigating climate change by sequestering a high amount of carbon. The potential carbon stock of the forest can be influenced by many factors. Therefore, studying these factors is crucial for understanding the determinants that affect the potential for woody carbon storage in the forest. This study was conducted to evaluate the potential for woody carbon stock and how it varies based on plant community types, as well as along altitudinal, slope, and aspect gradients in the Munessa dry Afromontane forest. Vegetation data was collected using systematic sampling. Five line transects were established at 100 m intervals along the altitudinal gradient between two consecutive transect lines. On each transect, 10 quadrats (20 x 20 m), separated by 200 m, were established. The woody carbon was estimated using an appropriate allometric equation formulated for tropical forests. The data was analyzed using one-way ANOVA in R software. The results showed that the total woody carbon stock of the Munessa forest was 210.43 ton/ha. The analysis of variance revealed that woody carbon density varied significantly based on environmental factors, while community types had no significant effect. The highest mean carbon stock was found at middle altitudes (2367-2533 m.a.s.l), lower slopes (0-13%), and west-facing aspects. The Podocarpus falcatus-Croton macrostachyus community type also contributed a higher woody carbon stock, as larger tree size classes and older trees dominated it. Overall, the potential for woody carbon sequestration in this study was strongly associated with environmental variables. Additionally, the uneven distribution of species with larger diameter at breast height (DBH) in the study area might be linked to anthropogenic factors, as the current forest growth indicates characteristics of a secondary forest. Therefore, our study suggests that the development and implementation of a sustainable forest management plan is necessary to increase the carbon sequestration potential of this forest and mitigate climate change.

Keywords: munessa forest, woody carbon stock, environmental factors, climate mitigation

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Authors: Dalila Hocine, Mohammed Said Belkaid, Abderahmane Moussi

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In this study, pure rutile TiO2 thin films were directly synthesized on silicon substrates by Atmospheric Pressure Chemical Vapor Deposition technique (APCVD) using TiCl4 as precursor. We studied the physicochemical properties and the optical properties of the produced coatings by means of standard characterization techniques of Fourier Transform Infrared Spectroscopy (FTIR) combined with UV-Vis Reflectance Spectrophotometry. The absorption peaks at 423 cm-1 and 610 cm-1 were observed for the rutile TiO2 thin films, by FTIR measurements. The absorption peak at 739 cm-1 due to the vibration of the Ti-O bonds, was also detected. UV-Vis Reflectance Spectrophotometry is employed for measuring the optical band gap from the measurements of the TiO2 films reflectance. The optical band gap was then extracted from the reflectance data for the TiO2 sample. It was estimated to be 3.05 eV which agrees with the band gap of commercial rutile TiO2 sample.

Keywords: titanium dioxide, physicochemical properties, APCVD, FTIR, band gap

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Authors: Mardin Abdalqadir, Paul Adzakro, Tannaz Pak, Sina Rezaei Gomari

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Climate change and global warming recently became significant concerns due to the massive emissions of greenhouse gases into the atmosphere, predominantly CO2 gases. Therefore, it is necessary to find sustainable and inexpensive methods to capture the greenhouse gasses and protect the environment for live species. The application of naturally available and cheap adsorbents of carbon such as clay minerals became a great interest. However, the minerals prone to low storage capacity despite their high affinity to adsorb carbon. This paper aims to explore ways to improve the pore volume and surface area of two selected clay minerals, ‘montmorillonite and kaolinite’ by acid treatment to overcome their low storage capacity. Montmorillonite and kaolinite samples were treated with different sulfuric acid concentrations (0.5, 1.2 and 2.5 M) at 40 °C for 8 hours to achieve the above aim. The grain size distribution and morphology of clay minerals before and after acid treatment were explored with Scanning Electron Microscope to evaluate surface area improvement. The ImageJ software was used to find the porosity and pore volume of treated and untreated clay samples. The structure of the clay minerals was also analyzed using an X-ray Diffraction machine. The results showed that the pore volume and surface area were increased substantially through acid treatment, which speeded up the rate of carbon dioxide adsorption. XRD pattern of kaolinite did not change after sulfuric acid treatment, which indicates that acid treatment would not affect the structure of kaolinite. It was also discovered that kaolinite had a higher pore volume and porosity than montmorillonite before and after acid treatment. For example, the pore volume of untreated kaolinite was equal to 30.498 um3 with a porosity of 23.49%. Raising the concentration of acid from 0.5 M to 2.5 M in 8 hours’ time reaction led to increased pore volume from 30.498 um3 to 34.73 um3. The pore volume of raw montmorillonite was equal to 15.610 um3 with a porosity of 12.7%. When the acid concentration was raised from 0.5 M to 2.5 M for the same reaction time, pore volume also increased from 15.610 um3 to 20.538 um3. However, montmorillonite had a higher specific surface area than kaolinite. This study concludes that clay minerals are inexpensive and available material sources to model the realistic conditions and apply the results of carbon capture to prevent global warming, which is one of the most critical and urgent problems in the world.

Keywords: acid treatment, kaolinite, montmorillonite, pore volume, porosity, surface area

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Authors: Dilip Depan, Austin Simoneaux, William Chirdon, Ahmed Khattab

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In this study, we present a novel approach to synthesize polymer nanocomposites with nanohybrid shish-kebab architecture (NHSK). For this low-density and high density polyethylene (PE) was crystallized on various carbon nano-fillers using a novel and convenient method to prepare high-yield NHSK. Polymer crystals grew epitaxially on carbon nano-fillers using a solution crystallization method. The mixture of polymer and carbon fillers in xylene was flocculated and precipitated in ethanol to improve the product yield. Carbon nanofillers of varying diameter were also used as a nucleating template for polymer crystallization. The morphology of the prepared nanocomposites was characterized scanning electron microscopy (SEM), while differential scanning calorimetry (DSC) was used to quantify the amount of crystalline polymer. Interestingly, whatever the diameter of the carbon nanofiller is, the lamellae of PE is always perpendicular to the long axis of nanofiller. Surface area analysis was performed using BET. Our results indicated that carbon nanofillers of varying diameter can be used to effectively nucleate the crystallization of polymer. The effect of molecular weight and concentration of the polymer was discussed on the basis of chain mobility and crystallization capability of the polymer matrix. Our work shows a facile, rapid, yet high-yield production method to form polymer nanocomposites to reveal application potential of NHSK architecture.

Keywords: carbon nanotubes, polyethylene, nanohybrid shish-kebab, crystallization, morphology

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Authors: Milad Nooshadi, Alessandro Manzardo

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CO₂ emissions in the atmosphere continue to rise, mostly as a result of the combustion of fossil fuels. CO₂ injection into the oceans and geological formation as a process of physical carbon capture are two of the most promising emerging strategies for mitigating climate change and global warming. The purpose of this research is to evaluate the two mentioned methods of CO₂ sequestration and to assess information on previous and current advancements, limitations, and uncertainties associated with carbon sequestration in order to identify possible prospects for ensuring the timely implementation of the technology, such as determining how governments and companies can gain a better understanding of CO₂ storage in terms of which media have the most applicable capacity, which type of injection has the fewer environmental impact, and how much carbon sequestration and storage will cost. The behavior of several forms is characterized as a near field, a far field, and a see-floor in ocean storage, and three medias in geological formations as an oil and gas reservoir, a saline aquifer, and a coal bed. To determine the capacity of various forms of media, an analysis of some models and practical experiments are necessary. Additionally, as a major component of sequestration, the various injection methods into diverse media and their monitoring are associated with a variety of environmental impacts and financial consequences.

Keywords: carbon sequestration, ocean storage, geologic storage, carbon transportation

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Authors: Atefeh Kalantari

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The increase in population and energy consumption has caused environmental crises such as the energy crisis, increased pollution, and climate change, all of which have resulted in a decline in the quality of life, especially in urban environments. Iran is one of the developing countries which faces several challenges concerning energy use and environmental sustainability such as air pollution, climate change, and energy security. On the other hand, due to its favorable geographic characteristics, Iran has diverse and accessible renewable sources, which provide appropriate substitutes to reduce dependence on fossil fuels. Sustainable development programs and post-carbon cities rely on implementing energy policies in different sectors of society, particularly, the built environment sector is one of the main ones responsible for energy consumption and carbon emissions for cities. Because of this, several advancements and programs are being implemented to promote energy efficiency for urban planning, and city experts, like others, are looking for solutions to deal with these problems. Among the solutions provided for this purpose, low-carbon design can be mentioned. Among the different scales, the neighborhood can be mentioned as a suitable scale for applying the principles and solutions of low-carbon urban design; Because the neighborhood as a "building unit of the city" includes elements and flows that all affect the number of CO2 emissions. The article aims to provide criteria for designing a low-carbon and carbon-free neighborhood through descriptive methods and secondary data analysis. The ultimate goal is to promote energy efficiency and create a more resilient and livable environment for local residents.

Keywords: climate change, low-carbon urban design, carbon-free neighborhood, resilience

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Authors: Neha Asthana, Vishal Krishna Prasad

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Reverse logistics and green supply chain form an interconnected and interwoven network of parameters that contribute to enhancement and incremental exchange in the triple bottom line in the consistently changing and fragmenting markets of the globalizing markets of today. Reverse logistics not only contributes to completing the supply chain in a comprehensive and synchronized manner but also contributes to a significant degree in optimizing green supply chains through procedures such as recycling, refurbishing etc. contributing to waste reduction. Carbon trading, owing to its limitations in the global context and being in a nascent stage seeks plethora of research to determine its full application in synergy with reverse logistics and green supply chain.

Keywords: reverse logistics, carbon trading, carbon emissions, green supply chain

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Authors: Mitsuhiro Okayasu, Lele Yang, Koji Shimotsu

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The effects of microstructural characteristics on the mechanical and hydrogen embrittlement properties of 1,800MPa grade hot stamping carbon steel were investigated experimentally. The tensile strength increased with increasing the hot stamping temperature until around 921°C, but that decreased with increasing the temperature in more than 921°C due to the increment of the size of lath martensite and prior austenite. With the hot stamping process, internal strain was slightly created in the sample, which led to the slight increment of the hardness value although no clear change of the microstructural formation was detected. Severity of hydrogen embrittlement was investigated using the hot stamped carbon steels after the immersion in a hydrogen gas, and that was directly attributed to the infiltration of the hydrogen into their grain boundaries. The high strength carbon steel with tiny lath martensite microstructure could make severe hydrogen brittleness as the hydrogen was strongly penetrated in the grain boundaries in the hydrogen gas for a month. Because of weak embrittlement for the as-received carbon (ferrite and pearlite), hydrogen embrittlement is caused by the high internal strain and high dislocation density. The hydrogen embrittlement for carbon steel is attributed to amount of the hydrogen immersed in-between grain boundaries, which is caused by the dislocation density and internal strain.

Keywords: hydrogen embrittlement, hot stamping process, carbon steel, mechanical property

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Authors: Alvaro Ramírez, Martín Muñoz-Morales, Ester López- Fernández, Javier Llanos, C. Ania

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Carbon blacks are value-added materials typically produced through the incomplete combustion or thermal decomposition of hydrocarbons. Traditionally, they have been used as catalysts in many different applications, but in the last decade, their potential in green chemistry has gained significant attention. Among them, the electrochemical production of H₂O₂ has attracted interest because of their properties as high oxidant capacity or their industrial interest as a bleaching agent. Carbon blacks are commonly used in this application in a catalytic ink that is drop-casted on supporting electrodes and acts as catalysts for the electrochemical production of H₂O₂ through oxygen reduction reaction (ORR). However, the different structural and electrochemical behaviors of each type of carbon black influence their applications. In this line, the term ‘carbon black’, has to be considered as a generic name that does not guarantee any physicochemical properties if any further description is mentioned. In fact, different specific surface area (SSA), surface functional groups, porous structure, and electro catalysts effect seem very important for electrochemical applications, and considerable differences were found during the analysis of four types of carbon blacks. Thus, the aim of this work is to evaluate the influence of SSA, porous structure, oxygen functional groups, and structural defects to differentiate among these carbon blacks (e.g. Vulcan XC72, Superior Graphite Co, Printex XE2, and Prolabo) for H₂O₂ production via ORR, using carbon paper as electrode support with improved selectivity and efficiency. Results indicate that the number and size of pores, along with surface functional groups, are key parameters that significantly affect the overall process efficiency.

Keywords: carbon blacks, oxygen reduction reaction, hydrogen peroxide, porosity, surface functional groups

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Authors: Kamila Widziewicz-Rzonca

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The presence of PM bound water as an integral chemical compound of suspended aerosol particles (PM) has become one of the hottest issues in recent years. The UN climate summits on climate change (COP24) indicate that PM of anthropogenic origin (released mostly from coal combustion) is directly responsible for climate change. Chemical changes at the particle-liquid (water) interface determine many phenomena occurring in the atmosphere such as visibility, cloud formation or precipitation intensity. Since water-soluble particles such as nitrates, sulfates, or sea salt easily become cloud condensation nuclei, they affect the climate for example by increasing cloud droplet concentration. Aerosol water is a master component of atmospheric aerosols and a medium that enables all aqueous-phase reactions occurring in the atmosphere. Thanks to a thorough bibliometric analysis conducted using CiteSpace Software, it was possible to identify past trends and possible future directions in measuring aerosol-bound water. This work, in fact, doesn’t aim at reviewing the existing literature in the related topic but is an in-depth bibliometric analysis exploring existing gaps and new frontiers in the topic of PM-bound water. To assess the major scientific areas related to PM-bound water and clearly define which among those are the most active topics we checked Web of Science databases from 1996 till 2018. We give an answer to the questions: which authors, countries, institutions and aerosol journals to the greatest degree influenced PM-bound water research? Obtained results indicate that the paper with the greatest citation burst was Tang In and Munklewitz H.R. 'water activities, densities, and refractive indices of aqueous sulfates and sodium nitrate droplets of atmospheric importance', 1994. The largest number of articles in this specific field was published in atmospheric chemistry and physics. An absolute leader in the quantity of publications among all research institutions is the National Aeronautics Space Administration (NASA). Meteorology and atmospheric sciences is a category with the most studies in this field. A very small number of studies on PM-bound water conduct a quantitative measurement of its presence in ambient particles or its origin. Most articles rather point PM-bound water as an artifact in organic carbon and ions measurements without any chemical analysis of its contents. This scientometric study presents the current and most actual literature regarding particulate bound water.

Keywords: systematic review, aerosol-bound water, PM-bound water, CiteSpace, knowledge domain

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Authors: Raviteja Chintala

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Water shortage in many areas of the world have predominantly increased the demand for efficient methods involved in the production of drinking water, So purification of water invoking cost effective and efficient methods is a challenging field of research. In this regard, Reverse osmosis membrane desalination of both seawater and inland brackish water is currently being deployed in various locations around the world. In the present work an attempt is made to integrate these existing technologies with novel method, Wherein carbon nanotubes at the lab scale are prepared which further replace activated carbon tubes being used traditionally. This has proven to enhance the efficiency of the water filter, Effectively neutralising most of the organic impurities. Furthermore, This ensures the reduction in TDS. Carbon nanotubes have wide range in scope of applications such as composite reinforcements, Field emitters, Sensors, Energy storage and energy conversion devices and catalysts support phases, Because of their unusual mechanical, Electrical, Thermal and structural properties. In particular, The large specific surface area, as well as the high chemical and thermal stability, Makes carbon nanotube an attractive adsorbent in waste water treatment. Carbon nanotubes are effective in eliminating these harmful media from water as an adsorbent. In this work, Candle soot method has been incorporated for the preparation of carbon nanotubes and mixed with activated charcoal in different compositions. The effect of composition change is monitored by using TDS measuring meter. As the composition of Nano carbon increases, The TDS of the water gradually decreases. In order to enhance the life time for carbon filter, Nano tubes are provided with larger surface area.

Keywords: TDS (Total Dissolved Solids), carbon nanotubes, water, candle soot

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Authors: Nidhi Nalin

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This study is theoretical modelling of the fermentation process of glucose in agricultural wastes like discarded peaches to produce hydrogen, acetic acid, and carbon dioxide using Thermotoga neopolitana bacteria. The hydrogen gas produced in this process can be used in hydrogen fuel cells to generate power, and the fermented broth with acetic acid and salts could be utilized as salty vinegar if enough acetic acid is produced. The theoretical modelling was done using SuperPro software, and the results indicated how much sugar (discarded peaches) is required to produce both hydrogen and vinegar for the process to be profitable.

Keywords: fermentation, thermotoga, hydrogen, vinegar, biofuel

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Authors: Kevser Dincer, Basma Waisi, M. Ozan Ozdemir, Ugur Pasaogullari, Jeffrey McCutcheon

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Nanofibers are defined as fibers with diameters less than 100 nanometers. They can be produced by interfacial polymerization, electrospinning and electrostatic spinning. In this study, behaviours of activated carbon nano fiber (ACNF), carbon nano-fiber (CNF), Polyacrylonitrile/carbon nanotube (PAN/CNT), Polyvinyl alcohol/nano silver (PVA/Ag) in PEM fuel cells are investigated experimentally. This material was used as gas diffusion layer (GDL) in PEM fuel cells. When the performances of these cells are compared to each other at 5x5 cm2 cell, it is found that the PVA/Ag exhibits the best performance among all. In this work, nano fiber and nano fiber/nano particles electrical conductivities have been studied to understand their effects on PEM fuel cell performance. According to the experimental results, the maximum electrical conductivity performance of the fuel cell with nanofiber was found to be at PVA/Ag. The electrical conductivities of CNF, ACNF, PAN/CNT are lower for PEM. The resistance of cell with PVA/Ag is lower than the resistance of cell with PAN/CNT, ACNF, CNF.

Keywords: proton exchange membrane fuel cells, electrospinning, carbon nano fiber, activate carbon nano-fiber, PVA fiber, PAN fiber, carbon nanotube, nano particle nanocomposites

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Authors: E. Güler, M. Güler

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We present some elastic parameters of cubic fluorite type uranium dioxide (UO2) with a recent EAM type interatomic potential through geometry optimization calculations. Typical cubic elastic constants, bulk modulus, shear modulus, young modulus and other related elastic parameters were calculated during research. After calculations, we compared our results not only with the available theoretical data but also with previous experimental results. Our results are consistent with experiments and compare well the former theoretical results of the considered parameters of UO2.

Keywords: UO2, elastic constants, bulk modulus, mechanical properties

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Authors: E. Güler, M. Güler

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We report some elastic quantities of cubic fluorite type plutonium dioxide (PuO2) with a recent EAM type interatomic potential through geometry optimization calculations. Typical cubic elastic constants, bulk modulus, shear modulus, young modulus and other related elastic quantities were calculated during present research. After present calculations, we have compared our results with the existing theoretical data of literature. Our results are consistent with previous theoretical findings of the considered parameters of PuO2.

Keywords: PuO2, elastic properties, bulk modulus, mechanical properties

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Authors: Amalka Nawarathna, Nirodha Fernando, Zaid Alwan

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Global carbon reduction is not merely a responsibility of environmentally advanced developed countries, but also a responsibility of developing countries regardless of their less impact on global carbon emissions. In recognition of that, Sri Lanka as a developing country has initiated promoting green building construction as one reduction strategy. However, notwithstanding the increasing attention on Embodied Carbon (EC) reduction in the global building sector, they still mostly focus on Operational Carbon (OC) reduction (through improving operational energy). An adequate attention has not yet been given on EC estimation and reduction. Therefore, this study aims to identify the reasons for the slow uptake of EC estimation in the Sri Lankan building sector. To achieve this aim, 16 numbers of global barriers to estimate EC were identified through existing literature. They were then subjected to a pilot survey to identify the significant reasons for the slow uptake of EC estimation in the Sri Lankan building sector. A questionnaire with a three-point Likert scale was used to this end. The collected data were analysed using descriptive statistics. The findings revealed that 11 out of 16 challenges/ barriers are highly relevant as reasons for the slow uptake in estimating EC in buildings in Sri Lanka while the other five challenges/ barriers remain as moderately relevant reasons. Further, the findings revealed that there are no low relevant reasons. Eventually, the paper concluded that all the known reasons are significant to the Sri Lankan building sector and it is necessary to address them in order to upturn the attention on EC reduction.

Keywords: embodied carbon emissions, embodied carbon estimation, global carbon reduction, Sri Lankan building sector

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Authors: C. Malça, N. Alves, A. Mateus

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This work was one of the tasks of the Manufacturing2Client project, whose objective was to develop a frontal deflector to be commercialized in the automotive industry, using new project and manufacturing methods. In this task, in particular, it was proposed to develop the ability to predict computationally the aerodynamic influence of flow in vehicles, in an effort to reduce fuel consumption in vehicles from class 3 to 8. With this aim, two deflector models were developed and their aerodynamic performance analyzed. The aerodynamic study was done using the Computational Fluid Dynamics (CFD) software Ansys CFX and allowed the calculation of the drag coefficient caused by the vehicle motion for the different configurations considered. Moreover, the reduction of diesel consumption and carbon dioxide (CO2) emissions associated with the optimized deflector geometry could be assessed.

Keywords: erodynamic analysis, CFD, CO2 emissions, drag coefficient, frontal deflector, fuel consumption

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Authors: Mohammed Umar Manko

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A series of batch experiments were conducted in order to investigate the feasibility of Balanitesaegyptiaca seeds based activated carbon as compared with industrial activated carbon for the removal of chromium and lead ions from aqueous solution by the adsorption process within 30 to 150 minutes contact time. The activated samples were prepared using zinc chloride and tetraoxophophate(VI) acid. The results obtained showed that the activated carbon of Balanitesaegyptiaca seeds studied had relatively high adsorption capacities for these heavy metal ions compared with industrial Activated Carbon. The percentage removal of Cr (VI) and lead (II) ions by the three activated carbon samples were 64%, 70% and 71%; 60%, 66% and 60% respectively. Adsorption equilibrium was established in 90 minutes for the heavy metal ions. The equilibrium data fitted the pseudo second order out of the pseudo first, pseudo second, Elovich ,Natarajan and Khalaf models tested. The investigation also showed that the adsorbents can effectively remove metal ions from similar wastewater and aqueous media.

Keywords: activated carbon, pseudo second order, chromium, lead, Elovich model

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Authors: Laura Frydel, Piotr M. Slomkiewicz, Beata Szczepanik

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Triclosan has been used as a disinfectant in many medical products, such as: hand disinfectant soaps, creams, mouthwashes, pastes and household cleaners. Due to its strong antimicrobial activity, triclosan is becoming more and more popular and the consumption of disinfectants with triclosan in it is increasing. As a result, this compound increasingly finds its way into waters and soils in an unchanged form, pollutes the environment and may have a negative effect on organisms. The aim of this study was to investigate the synthesis of cellulose-based halloysite-carbon adsorbent and perform its characterization. The template in the halloysite-carbon adsorbent was halloysite nanotubes and the carbon precursor was microcrystalline cellulose. Scanning electron microscope (SEM) images were obtained and the elementary composition (qualitative and quantitative) of the sample was determined by energy dispersion spectroscopy (EDS). The identification of the crystallographic composition of the halloysite nanotubes and the sample of the halloysite-carbon composite was carried out using the X-ray powder diffraction (XRPD) method. The FTIR spectra were acquired before and after the adsorption process in order to determine the functional groups on the adsorbent surface and confirm the interactions between adsorbent and adsorbate molecules. The parameters of the porous structure of the adsorbent, such as the specific surface area (Brunauer-Emmett-Teller method), the total pore volume and the volume of mesopores and micropores were determined. Total carbon and total organic carbon were also determined in the samples. A cellulose-based halloysite-carbon adsorbent was used to remove triclosan from water. The degree of removal of triclosan from water was approximately 90%. The results indicate that the halloysite-carbon composite can be successfully used as an effective adsorbent for removing triclosan from water.

Keywords: Adsorption, cellulose, halloysite, triclosan

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Authors: M. Bharath, Vasudevan Raghavan, B. V. S. S. S. Prasad, S. R. Chakravarthy

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In this experimental study, effects of addition of rice husk on coal gasification in a bubbling fluidized bed gasifier, operating at atmospheric pressure with air as gasifying agent, are reported. Rice husks comprising of 6.5% and 13% by mass are added to coal. Results show that, when rice husk is added the methane yield increases from volumetric percentage of 0.56% (with no rice husk) to 2.77% (with 13% rice husk). CO and H₂ remain almost unchanged and CO₂ decreases with addition of rice husk. The calorific value of the synthetic gas is around 2.73 MJ/Nm³. All performance indices, such as cold gas efficiency and carbon conversion, increase with addition of rice husk.

Keywords: bubbling fluidized bed reactor, calorific value, coal gasification, rice husk

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Authors: Shiliang Wu, Huanxin Zhang, Aditya Kumar

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There have been increasing concerns on atmospheric mercury as a toxic and bioaccumulative pollutant in the global environment. Global change, including changes in climate change, land use, land cover and wildfires activities can all have significant impacts on atmospheric mercury. In this study, we use a global chemical transport model (GEOS-Chem) to examine the potential impacts from global change on atmospheric mercury. All of these factors in the context of global change are found to have significant impacts on the long-term evolution of atmospheric mercury and can substantially alter the global source-receptor relationships for mercury. We also estimate the global Hg emissions from wildfires for present-day and the potential impacts from the 2000-2050 changes in climate, land use and land cover and Hg anthropogenic emissions by combining statistical analysis with global data on vegetation type and coverage as well as fire activities. Present global Hg wildfire emissions are estimated to be 612 Mg year-1. Africa is the dominant source region (43.8% of global emissions), followed by Eurasia (31%) and South America (16.6%). We find significant perturbations to wildfire emissions of Hg in the context of global change, driven by the projected changes in climate, land use and land cover and Hg anthropogenic emissions. 2000-2050 climate change could increase Hg emissions by 14% globally. Projected changes in land use by 2050 could decrease the global Hg emissions from wildfires by 13% mainly driven by a decline in African emissions due to significant agricultural land expansion. Future land cover changes could lead to significant increases in Hg emissions over some regions (+32% North America, +14% Africa, +13% Eurasia). Potential enrichment of terrestrial ecosystems in 2050 in response to changes in Hg anthropogenic emissions could increase Hg wildfire emissions both globally (+28%) and regionally. Our results indicate that the future evolution of climate, land use and land cover and Hg anthropogenic emissions are all important factors affecting Hg wildfire emissions in the coming decades.

Keywords: climate change, land use, land cover, wildfires

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Authors: Vahidullah Tac, Ercan Gurses

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There have been numerous attempts at modelling carbon nanotube – polymer composites micromechanically in recent years, albeit to limited success. One of the major setbacks of the models used in the scientific community is the lack of regard to the different phases present in a nanocomposite. We employ a multi-phase micromechanical model that allows functionally grading certain phases to determine the mechanical properties of nanocomposites. The model has four distinct phases; the nanotube, the interface between the nanotube and polymer, the interphase, and the bulk matrix. Among the four phases, the interphase is functionally graded such that its moduli gradually decrease from some predetermined values to those of the bulk polymer. We find that the interface plays little role in stiffening/softening of the polymer per se , but instead, it is responsible for load transfer between the polymer and the carbon nanotube. Our results indicate that the carbon nanotube, as well as the interphase, have significant roles in stiffening the composite. The results are then compared to experimental findings and the interphase is tuned accordingly.

Keywords: carbon nanotube, composite, interphase, micromechanical modeling

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Authors: Bengan Simbarashe Manwere

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The entire African continent, comprising 55 countries, holds a 2% share of the global carbon market. The World Bank attributes the continent’s insignificant share and participation in the carbon market to the limited access to electricity. Approximately 800 million people spread across 47 African countries generate as much power as Spain, with a population of 45million. Only South Africa and North Africa have carbon-reduction investment opportunities on the continent and dominate the 2% market share of the global carbon market. On the back of the 2015 Paris Agreement, South Africa signed into law the Carbon Tax Act 15 of 2019 and the Customs and Excise Amendment Act 13 of 2019 (Gazette No. 4280) on 1 June 2019. By these laws, South Africa was ushered into the league of active global carbon market players. By increasing the cost of production by the rate of R120/tCO2e, the tax intentionally compels the internalization of pollution as a cost of production and, relatedly, stimulate investment in clean technologies. The first phase covered the 1 June 2019 – 31 December 2022 period during which the tax was meant to escalate at CPI + 2% for Scope 1 emitters. However, in the second phase, which stretches from 2023 to 2030, the tax will escalate at the inflation rate only as measured by the consumer price index (CPI). The Carbon Tax Act provides for carbon allowances as mitigation strategies to limit agents’ carbon tax liability by up to 95% for fugitive and process emissions. Although the June 2019 Carbon Tax Act explicitly makes provision for a carbon trading scheme (CTS), the carbon trading regulations thereof were only finalised in December 2020. This points to a delay in the establishment of a carbon trading scheme (CTS). Relatedly, emitters in South Africa are not able to benefit from the 95% reduction in effective carbon tax rate from R120/tCO2e to R6/tCO2e as the Johannesburg Stock Exchange (JSE) has not yet finalized the establishment of the market for trading carbon credits. Whereas most carbon trading schemes have been designed and constructed from the beginning as new tailor-made systems in countries the likes of France, Australia, Romania which treat carbon as a financial product, South Africa intends, on the contrary, to leverage existing trading infrastructure of the Johannesburg Stock Exchange (JSE) and the Clearing and Settlement platforms of Strate, among others, in the interest of the Paris Agreement timelines. Therefore the carbon trading scheme will not be constructed from scratch. At the same time, carbon will be treated as a commodity in order to align with the existing institutional and infrastructural capacity. This explains why the Carbon Tax Act is silent about the involvement of the Financial Sector Conduct Authority (FSCA).For South Africa, there is need to establish they equilibrium stability of the CTS. This is important as South Africa is an innovator in carbon trading and the successful trading of carbon credits on the JSE will lead to imitation by early adopters first, followed by the middle majority thereafter.

Keywords: carbon trading scheme (CTS), Johannesburg stock exchange (JSE), carbon tax act 15 of 2019, South Africa

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Authors: Chao Hu, Xinwen Liao, Qing-Hua Qin, Gang Wang

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The hierarchical carbon nanotube (CNT)/carbon fiber (CF)/high density polyethylene (HDPE) was fabricated via compound extrusion and injection molding, in which to author’s best knowledge CNT was employed as a nano-coatings on the surface of CF for the first time by spray coating technique. The CNT coatings relative to CF was set at 1 wt% and the CF content relative to the composites varied from 0 to 25 wt% to study the influence of CNT coatings and CF contents on the mechanical, thermal and morphological performance of this hierarchical composites. The results showed that with the rise of CF contents, the mechanical properties, including the tensile properties, flexural properties, and hardness of CNT/CF/HDPE composites, were effectively improved. Furthermore, the CNT-coated composites showed overall higher mechanical performance than the uncoated counterparts. It can be ascribed to the enhancement of interfacial bonding between the CF and HDPE via the incorporation of CNT, which was demonstrated by the scanning electron microscopy observation. Meanwhile, the differential scanning calorimetry data indicated that by the introduction of CNT and CF, the crystallization temperature and crystallinity of HDPE were affected while the melting temperature did not have an obvious alteration.

Keywords: carbon fibers, carbon nanotubes, extrusion, high density polyethylene

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Authors: Anu Shrestha, Krassi Rumchev, Ben Mullins, Yun Zhao, Linda Selvey

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Cycling is often promoted as a means of reducing vehicular congestion, noise and greenhouse gas and air pollutant emissions in urban areas. It is also indorsed as a healthy means of transportation in terms of reducing the risk of developing a range of physical and psychological conditions. However, people who cycle regularly may not be aware that they can become exposed to high levels of Vehicular Air Pollutants (VAP) emitted by nearby traffics and therefore experience adverse health effects as a result. The study will highlight the present scenario of ambient air pollution level in different cycling routes in Perth and also highlight significant contribution to the understanding of health risks that cyclist may face from exposure to particulate air pollution. Methodology: This research was conducted in Perth, Western Austral and consisted of two groups of cyclists cycling near high (2 routes) and low (two routes) vehicular traffic roads, at high and low levels of exertion, during the cold and warm seasons. A sample size of 123 regular cyclists who cycled at least 80 km/week, aged 20-55, and non-smoker were selected for this study. There were altogether 100 male and 23 female who were asked to choose one or more routes among four different routes, and each participant cycled the route for warm or cold or both seasons. Cyclist who reported cardiovascular and other chronic health conditions (excluding asthma) were not invited into the study. Exposures to selected air pollutants were assessed by undertaking background and personal measurements alone with the measurement of heart and breathe rate of each participant. Finding: According to the preliminary study findings, the cyclists who used cycling route close to high traffic route were exposed to higher levels of measured air pollutants Nitrogen Oxide (NO₂) =0.12 ppm, sulfur dioxide (SO₂)=0.06 ppm and carbon monoxide (CO)=0.25 PPM compared to those who cycled away from busy roads. However, we measured high concentrations of particulate air pollution near one of the low traffic route which we associate with the close proximity to ferry station. Concluding Statement: As a conclusion, we recommend that cycling routes should be selected away from high traffic routes. If possible, we should also consider that if the cycling route is surrounded by the dense populated infrastructures, it can trap the pollutants and always facilitate in increasing inhalation of particle count among the cyclists.

Keywords: air pollution, carbon monoxide, cyclists' health, nitrogen dioxide, nitrogen oxide, respirable particulate matters

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Authors: Dewi Selvia Fardhyanti, Astrilia Damayanti

Abstract:

Coal tar is a liquid by-product of coal pyrolysis processes. This liquid oil mixture contains various kind of useful compounds such as benzoic aromatic compounds and phenolic compounds. These compounds are widely used as raw material for insecticides, dyes, medicines, perfumes, coloring matters, and many others. The coal tar was collected by pyrolysis process of coal obtained from PT Kaltim Prima Coal and Arutmin-Kalimantan. The experiments typically occurred at the atmospheric pressure in a laboratory furnace at temperatures ranging from 300 to 550oC with a heating rate of 10oC/min and a holding time of 1 hour at the pyrolysis temperature. Nitrogen gas has been used to obtain the inert condition and to carry the gaseous pyrolysis products. The pyrolysis transformed organic materials into gaseous components, small quantities of liquid, and a solid residue (coke) containing fixed amount of carbon and ash. The composition of gas which is produced from the pyrolysis is carbon monoxide, hydrogen, methane, and other hydrocarbon compounds. The gas was condensed and the liquid containing oil/tar and water was obtained. The Gas Chromatography-Mass Spectroscopy (GC-MS) was used to analyze the coal tar components. The obtained coal tar has the viscosity of 3.12 cp, the density of 2.78 g/cm3, the calorific value of 11,048.44 cal/g, and the molecular weight of 222.67. The analysis result showed that the coal tar contained more than 78 chemical compounds such as benzene, cresol, phenol, xylene, naphtalene, etc. The total phenolic compounds contained in coal tar is 33.25% (PT KPC) and 17.58% (Arutmin-Kalimantan). The total naphtalene compounds contained in coal tar is 14.15% (PT KPC) and 17.13% (Arutmin-Kalimantan).

Keywords: coal tar, pyrolysis, gas chromatography-mass spectroscopy

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Authors: SeyedKeivan Nateghi, Jan Kaczmarczyk

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People nowadays spend most of their time in buildings. Accordingly, maintaining a good quality of indoor air is very important. New universal matters related to the prevalence of Covid-19 also highlight the importance of indoor air conditioning in reducing the risk of virus infection. Cooling and Heating of a house will provide a suitable zone of air temperature for residents. One of the significant factors in energy demand is energy consumption in the building. In general, building divisions compose more than 30% of the world's fundamental energy requirement. As energy demand increased, greenhouse effects emerged that caused global warming. Regardless of the environmental damage to the ecosystem, it can spread infectious diseases such as malaria, cholera, or dengue to many other parts of the world. With the advent of the Covid-19 phenomenon, the previous instructions to reduce energy consumption are no longer responsive because they increase the risk of virus infection among people in the room. Two problems of high energy consumption and coronavirus infection are opposite. A classroom with 30 students and one teacher in Katowice, Poland, considered controlling two objectives simultaneal. The probability of transmission of the disease is calculated from the carbon dioxide concentration of people. Also, in a certain period, the amount of energy consumption is estimated by EnergyPlus. The effect of three parameters of number, angle, and time or schedule of opening windows on the probability of infection transmission and energy consumption of the class were investigated. Parameters were examined widely to determine the best possible condition for simultaneous control of infection spread and energy consumption. The number of opening windows is discrete (0,3), and two other parameters are continuous (0,180) and (8 AM, 2 PM). Preliminary results show that changes in the number, angle, and timing of window openings significantly impact the likelihood of virus transmission and class energy consumption. The greater the number, tilt, and timing of window openings, the less likely the student will transmit the virus. But energy consumption is increasing. When all the windows were closed at all hours of the class, the energy consumption for the first day of January was only 0.2 megajoules. In comparison, the probability of transmitting the virus per person in the classroom is more than 45%. But when all windows were open at maximum angles during class, the chance of transmitting the infection was reduced to 0.35%. But the energy consumption will be 36 megajoules. Therefore, school classrooms need an optimal schedule to control both functions. In this article, we will present a suitable plan for the classroom with natural ventilation through windows to control energy consumption and the possibility of infection transmission at the same time.

Keywords: Covid-19, energy consumption, building, carbon dioxide, energyplus

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Authors: Azeez O. Idris, Benjamin O. Orimolade, Potlako J. Mafa, Alex T. Kuvarega, Usisipho Feleni, Bhekie B. Mamba

Abstract:

We report a simple and cheaper method for the electrochemical detection of Se(IV) using carbon nanodots (CNDTs) prepared from oat. The carbon nanodots were synthesised by green and facile approach and characterised using scanning electron microscopy, high-resolution transmission electron microscopy, Fourier transform infrared spectroscopy, X-ray diffraction, and Raman spectroscopy. The CNDT was used to fabricate an electrochemical sensor for the quantification of Se(IV) in water. The modification of glassy carbon electrode (GCE) with carbon nanodots led to an increase in the electroactive surface area of the electrode, which enhances the redox current peak of [Fe(CN)₆]₃₋/₄‒ in comparison to the bare GCE. Using the square wave voltammetry, the detection limit and quantification limit of 0.05 and 0.167 ppb were obtained under the optimised parameters using deposition potential of -200 mV, 0.1 M HNO₃ electrolyte, electrodeposition time of 60 s, and pH 1. The results further revealed that the GCE-CNDT was not susceptible to many interfering cations except Cu(II) and Pb(II), and Fe(II). The sensor fabrication involves a one-step electrode modification and was used to detect Se(IV) in a real water sample, and the result obtained is in agreement with the inductively coupled plasma technique. Overall, the electrode offers a cheap, fast, and sensitive way of detecting selenium in environmental matrices.

Keywords: carbon nanodots, square wave voltammetry, nanomaterials, selenium, sensor

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