Search results for: carbon substrates

Authors: John Gichimu Mbaka, Jan Helmrich Martin von Baumbach, Celia Somlai, Denis Köpfer, Andreas Maeck, Andreas Lorke, Ralf Schäfer

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Leaf litter decomposition is an important process providing energy to biotic communities. Additionally, methane gas (CH4) has been identified as an important alternative source of carbon and energy in some freshwater food webs.Flow regulation and dams can strongly alter freshwater ecosystems, but little is known about the effect of small impoundments on leaf litter decomposition and methane derived carbon in streams. In this study, we tested the effect of small water storage impoundments on leaf litter decomposition rates and methane derived carbon. Leaf litter decomposition rates were assessed by comparing treatment sites located close to nine impoundments (Rheinland Pfalz state, Germany) and reference sites located far away from the impoundments.CH4 concentrations were measured in eleven impoundments and correlated with the δ13C values of two subfamilies of chironomid larvae (i.e. Chironomini and Tanypodinae). Leaf litter break down rates were significantly lower in study sites located immediately above the impoundments, especially associated with a reduction in the abundance of shredders. Chironomini larvae had the lower mean δ13C values (‒29.2 to ‒25.5 ‰), than Tanypodinae larvae (‒26.9 to ‒25.3 ‰).No significant relationships were established between CH4 concentrations and δ13C values of chironomids (p> 0.05).Mean δ13C values of chironomid larvae (mean: ‒26.8‰, range: ‒ 29.2‰ to ‒ 25.3‰) were similar to those of sedimentary organic matter (SOM) (mean: ‒28.4‰, range: ‒ 29.3‰ to ‒ 27.1‰) and tree leaf litter (mean: ‒29.8 ‰, range: ‒ 30.5‰ to ‒ 29.1‰). In conclusion, this study demonstrates that small impoundments may have a negative effect on leaf litter decomposition in forest streams and that CH4 has limited influence on the benthic food web in stream impoundments.

Keywords: river functioning, chironomids, Alder tree, stable isotopes, methane oxidation, shredder

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Authors: Yue Feng, Chun-jiang Wang, Zhi-long Huang

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The study of the sedimentary environment of Mesoproterozoic marine deposits in North China has attracted special attention in recent years. It is not clear that the sedimentary environment and the cause of formation of the sandstone strip and its internal carbonate cements and pyrite in the Mesoproterozoic Chuanlinggou Formation in North China. In this study, drilling core samples in North China were identified by microscopy, and their petrological characteristics such as mineral composition and structure were identified. The geochemical data of carbon and oxygen isotopes, total organic carbon (TOC) contents and total sulfur (TS) contents were obtained by processing and analyzing the samples. The samples are mainly quartz particles with low compositional maturity, combined with low value of TOC, it shows that the sedimentary environment of the sandy clastic is a sandy littoral sedimentary environment with relative strong hydrodynamic force, and then the sandstone strip in black shale are formed by the deposition of gravity flow. Analysis of TS values reflect sandstone bands formed in hypoxic environments. The carbonate cements and the pyrite in the sandstone belt are authigenic. The carbon isotope values of authigenic carbonate cements are negatively biased in comparison with the carbonate isotope of carbonate rocks in the same period, but it is more biased than the carbon isotopic values of anaerobic oxidation of methane (AOM) genetic carbonate rocks. Authigenic pyrite may be mainly due to the formation of HS- by the action of bacterial sulfate reduction (BSR) and Fe²⁺, their causes are in contact. This indicates that authigenic carbonate cements are mainly carbonate precipitates formed but are significantly affected by the effects of AOM. Summary, the sedimentary environment of the sandstone zone in the Chuanlinggou Formation in the North China is a shallow sea facies with iron rich and anoxic.

Keywords: sandstone strip, sedimentary environment, authigenic carbonate cements, authigenic pyrite, The Chuanlinggou group, North China

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Authors: Carla Palencia-Aguilar

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Calculations of Net Carbon Balance can be obtained by means of Net Biome Productivity (NBP), Net Ecosystem Productivity (NEP), and Net Primary Production (NPP). The latter is an important component of the biosphere carbon cycle and is easily obtained data from MODIS MOD17A3HGF; however, the results are only available yearly. To overcome data availability, bands 33 to 36 from MODIS MYD021KM (obtained on a daily basis) were analyzed and compared with NPP data from the years 2000 to 2021 in 7 sites where surface mining takes place in the Colombian territory. Coal, Gold, Iron, and Limestone were the minerals of interest. Scales and Units as well as thermal anomalies, were considered for net carbon balance per location. The NPP time series from the satellite images were filtered by using two Matlab filters: First order and Discrete Transfer. After filtering the NPP time series, comparing the graph results from the satellite’s image value, and running a linear regression, the results showed R2 from 0,72 to 0,85. To establish comparable units among NPP and bands 33 to 36, the Greenhouse Gas Equivalencies Calculator by EPA was used. The comparison was established in two ways: one by the sum of all the data per point per year and the other by the average of 46 weeks and finding the percentage that the value represented with respect to NPP. The former underestimated the total CO2 emissions. The results also showed that coal and gold mining in the last 22 years had less CO2 emissions than limestone, with an average per year of 143 kton CO2 eq for gold, 152 kton CO2 eq for coal, and 287 kton CO2 eq for iron. Limestone emissions varied from 206 to 441 kton CO2 eq. The maximum emission values from unfiltered data correspond to 165 kton CO2 eq. for gold, 188 kton CO2 eq. for coal, and 310 kton CO2 eq. for iron and limestone, varying from 231 to 490 kton CO2 eq. If the most pollutant limestone site improves its production technology, limestone could count with a maximum of 318 kton CO2 eq emissions per year, a value very similar respect to iron. The importance of gathering data is to establish benchmarks in order to attain 2050’s zero emissions goal.

Keywords: carbon dioxide, NPP, MODIS, MINING

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Authors: Shahab Zomorodbakhsh, Hayron Nesa Motevasel

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Water soluble compoundes were attached to single-walled carbon nanotubes (SWNTs) to form water-soluble nano pigments. functionalized SWNTs were then characterized by Fourier Transform Infrared spectroscopy (FT-IR), Raman spectroscopy, UV analysis, Transmission electron microscopy (TEM)and defunctionalization test and Representative results concerning the solubility. The product can be dissolved in water and High-resolution transmission electron microscope images showed that the SWNTs were efficiently functionalized, thus the p-stacking interaction between aromatic rings and COOH of SWNTs was considered responsible for the high solubility and High transmission electron in singlewall nanotubes.

Keywords: functionalized CNTs, singlewalled carbon nanotubes, water soluble compoundes, nano pigments

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Authors: Getachew Kuma Watiro

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The need for solar energy is constantly increasing and it is widely available on the earth’s surface. Photovoltaic technology is one of the most capable of all viable energy technology and is seen as a promising approach to the control era as it is readily available and has zero carbon emissions. Inexpensive and versatile solar cells have achieved the conversion efficiency and long life of dye-sensitized solar cells, improving the conversion efficiency from the sun to electricity. DSSCs have received a lot of attention for Various potential commercial uses, such as mobile devices and portable electronic devices, as well as integrated solar cell modules. The systematic reviews were used to show the critical impact of additive C-dots in the Dye-Sensitized solar cell for energy application technology. This research focuses on the following methods to synthesize nanoparticles such as facile, polyol, calcination, and hydrothermal technique. In addition to these, there are additives C-dots by the Hydrothermal method. This study deals with the progressive development of DSSC in photovoltaic technology. The applications of single and heterojunction structure technology devices were used (ZnO, NiO, SnO2, and NiO/ZnO/N719) and applied some additives C-dots (ZnO/C-dots /N719, NiO/C-dots /N719, SnO2 /C-dots /N719 and NiO/ZnO/C-dots/N719) and the effects of C-dots were reviewed. More than all, the technology of DSSC with C-dots enhances efficiency. Finally, recommendations have been made for future research on the application of DSSC with the use of these additives.

Keywords: dye-sensitized solar cells, heterojunction’s structure, carbon dot, conversion efficiency

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Authors: Karima Chergui, Hichem Amrani, Hammoudi Mazouz, Fatiha Mezaache

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Cemented femoral resurfacings have experienced a revival for younger and more active patients. Future developments have shown that the uncemented version eliminates failures related to cementing implants. A three-dimensional finite element method (FEM) simulation was carried out in order to exploit a new resurfacing prothesis design named MARMEL, proposed by a recent study with Co–Cr–Mo material, for comparing a hip uncemented resurfacing with a novel carbon fiber/polyamide 12 (CF/PA12) composite to other hip resurfacing implants with various bio materials. From FE analysis, the von Mises stress range for the Composite hip resurfacing was much lower than that in the other hip resurfacing implants used in this comparison. These outcomes showed that the biomimetic hip resurfacing had the potential to reduce stress shielding and prevent from bone fracture compared to conventional hip resurfacing implants.

Keywords: biomechanics, carbon–fibre polyamide 12, finite element analysis, hip resurfacing

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Authors: Asha Bhardwaj, Pushpendu Biswas

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Carbon Dots (CDs) are known to be absorbing in the UV and emitting in the blue to visible region [1-2]. As CDs have high bio compatibility, high emission efficiency, are environment friendly and are nontoxic in nature, they are a material of great importance for various biomedical as well as optoelectronic applications [3-6]. For bioimaging and photothermal therapy in cancer treatment CDs should be highly photostable, show interaction with NIR band [3], show quick excretion from the body and have high Quantum yields. NIR I stands for emission in the 650-950 nm region and NIR II stands for emission in the 1000-1700 nm range [4]. Penetration depth of NIR II is larger than that of NIR-1 or visible light [5]. Also, it shows heating effect which is beneficial for selective ablation of cancer cells while not harming the healthy cells. Therefore, efforts are being made by the scientific community to synthesize CDs which emit in the NIR II region. Here we report CDs emitting in all the three regions (Visible, NIR I and NIR II) of electromagnetic spectra ranging from 300-1150 nm. Wide range emissive CDs and Fe doped CDs are prepared by a one-step hydrothermal method. Fe concentration has been increased in steps to assess the contribution from Fe incorporation in the CD lattice [6]. The CDs emit in three wavelength ranges, from 300-600 nm, 600-800 nm (NIR I) and 900 – 1150 nm (NIR II). Such kind of broad emission behaviour in single system carbon dots is being reported for the first time. Further excitation wavelength (λex) dependent emission characteristics reveal that the emission peak wavelength values are unaffected by the changing excitation wavelength in the visible region. Also, NIR I and NIR II emission is observed only for 300 and 310 nm excitation, hinting towards two photon and three photon emission [4]. Emission from 650- 1150 nm is not observed for λex > 310 nm. Additionally, as expected the absorption spectra also ranges from 250-600 nm, as compared to commonly observed blue or UV absorption in CDs. The exquisite ultra-wide range emitting nontoxic CDs can find application not only as broad band emitters but also in photothermal therapy for cancer cell theranostics.

Keywords: Broad Emission, absorption, Carbon dots, NIR Emission

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Authors: Ahmed Saheel

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Enhanced oil recovery using carbon dioxide (CO₂-EOR) is a method that can increase oil production beyond what is typically achievable using conventional recovery methods by injecting, and hence storing, carbon dioxide (CO₂) in the oil reservoir. In Libya, plans are under way to source a proportion of this CO₂ from subsurface geology that is known from previous drilling to contain high volumes of CO₂. But first these subsurface volumes need to be more clearly defined and understood. Focusing on the Al-Harouj region of central Libya, ground gravity and airborne magnetic data from the LPI database and the African Magnetic Mapping Project respectively have been prepared and processed by Libyan Petroleum Institute (LPI) and Reid Geophysics Limited (RGL) to produce a range of grids and related products suitable for interpreting geological structure and to make recommendations for subsequent work that will assist CO₂ exploration for purposes of enhanced oil recovery (EOR).

Keywords: gravity, magnetic, deduced lineaments, upward continuation

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Authors: Oluwaseun A. Oyetade, Roelof J. Kriek

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The development of effective catalysts for the oxygen evolution reaction (OER) is of great importance to combat energy-related concerns in the environment. Herein, we report a one-step solvothermal method employed for the fabrication of nickel selenide hybrids (NiSe-Ni₃Se₂) and a series of nickel selenide hybrid/multiwalled carbon nanotube composites (NiSe-Ni₃Se₂/MWCNT) as electrocatalysts for OER in alkaline media. The catalytic activities of these catalysts were investigated via several electrochemical characterization techniques, such as linear sweep voltammetry, chronoamperometric studies at constant potential, electrochemical surface area determination, and Tafel slope calculation, under alkaline conditions. Morphological observations demonstrated the agglomeration of non-uniform NiSe-Ni₃Se₂ microspheres around carbon nanotubes (CNTs), demonstrating the successful synthesis of NiSe-Ni₃Se₂/MWCNT nanocomposites. Among the tested electrocatalysts, the 20% NiSe-Ni₃Se₂/MWCNT nanocomposite demonstrated the highest activity, exhibiting an overpotential of 325 mV to achieve a current density of 10 mA.cm⁻² in 0.1 mol.dm⁻³ KOH solution. The NiSe-Ni₃Se₂/MWCNT nanocomposites showed improved activity toward OER compared to bare NiSe-Ni₃Se₂ hybrids and MWCNTs, exhibiting an overpotential of 528, 392 and 434 mV for 10%, 30% and 50% NiSe-Ni₃Se₂/MWCNT nanocomposites, respectively. These results compare favourably to the overpotential of noble catalysts, such as RuO₂ and IrO₂. Our results imply that the addition of MWCNTs increased the activity of NiSe-Ni₃Se₂ hybrids due to an increased number of catalytic sites, dispersion of NiSe-Ni₃Se₂ hybrid nanoparticles, and electronic conductivity of the nanocomposites. These nanocomposites also demonstrated better long-term stability compared to NiSe-Ni₃Se₂ hybrids and MWCNTs. Hence, NiSe-Ni₃Se₂/MWCNT nanocomposites possess the potential as effective electrocatalysts for OER in alkaline media.

Keywords: carbon nanotubes, electrocatalysts, nanocomposites, nickel selenide hybrids, oxygen evolution reaction

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Authors: Yogish Huchaiah, Chandrashekara Krishnappa

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This study considers the optimization and validation of experimental results using Multi-Functional Criteria Technique (MFCT). MFCT is concerned with structuring and solving decision and planning problems involving multiple variables. Production of biodiesel from Composite Oil Methyl Esters (COME) of Jatropha and Pongamia oils, mixed in various proportions and Biodiesel thus obtained from two step transesterification process were tested for various Physico-Chemical properties and it has been ascertained that they were within limits proposed by ASTME. They were blended with Petrodiesel in various proportions. These Methyl Esters were blended with Petrodiesel in various proportions and coded. These blends were used as fuels in a computerized CI DI engine to investigate Performance and Emission characteristics. From the analysis of results, it was found that 180MEM4B20 blend had the maximum Performance and minimum Emissions. To validate the experimental results, MFCT was used. Characteristics such as Fuel Consumption (FC), Brake Power (BP), Brake Specific Fuel Consumption (BSFC), Brake Thermal Efficiency (BTE), Carbon dioxide (CO2), Carbon Monoxide (CO), Hydro Carbon (HC) and Nitrogen oxide (NOx) were considered as dependent variables. It was found from the application of this method that the optimized combination of Injection Pressure (IP), Mix and Blend is 178MEM4.2B24. Overall corresponding variation between optimization and experimental results was found to be 7.45%.

Keywords: COME, IP, MFCT, optimization, PI, PN, PV

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Authors: L. M. Ombaka, R. S. Oosthuizen, P. G. Ndungu, V. O. Nyamori

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Understanding the role of nitrogen species on the catalytic properties of nitrogen-doped carbon nanotubes (N-CNTs) as catalysts supports is critical as nitrogen species influence the support’s properties. To evaluate the influence of pyrrolic nitrogen on the physicochemical properties and catalytic activity of N-CNTs supported Pd (Pd/N-CNTs); N-CNTs containing varying pyrrolic contents were synthesized. The catalysts were characterised by the use of transmission electron microscope (TEM), scanning electron microscope, X-ray photoelectron spectroscopy (XPS), X-ray diffraction, Fourier transform infrared spectroscopy, and temperature programmed reduction. TEM analysis showed that the Pd nanoparticles were mainly located along the defect sites on N-CNTs. XPS analysis revealed that the abundance of Pd0 decreased while that of Pd2+ increased as the quantity of pyrrolic nitrogen increased. The increase of Pd2+ species was accredited to the formation of stable Pd-N coordination complexes which prevented further reduction of Pd2+ to Pd0 during synthesis. The formed Pd-N complexes increased the stability and dispersion of Pd2+ nanoparticles. The selective hydrogenation of nitrobenzophenone to aminobenzophenone over Pd/N-CNTs was compared to that of Pd on carbon nanotubes (Pd/CNTs). Pd/N-CNTs showed a higher catalytic activity and selectivity compared with Pd/CNTs. Pyrrolic nitrogen functional groups significantly promoted the selectivity towards aminobenzophenone formation.

Keywords: pyrrolic N-CNTs, hydrogenation reactions, chemical vapour deposition technique

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Authors: Wilaiwan Sornpoon, Sébastien Bonnet, Savitri Garivait

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Continuous measurements of greenhouse gases (GHGs) emitted from soils are required to understand diurnal and seasonal variations in soil emissions and related mechanism. This understanding plays an important role in appropriate quantification and assessment of the overall change in soil carbon flow and budget. This study proposes to monitor GHGs emissions from soil under sugarcane cultivation in Thailand. The measurements were conducted over 379 days. The results showed that the total net amount of GHGs emitted from sugarcane plantation soil amounts to 36 Mg CO2eq ha-1. Carbon dioxide (CO2) and nitrous oxide (N2O) were found to be the main contributors to the emissions. For methane (CH4), the net emission was found to be almost zero. The measurement results also confirmed that soil moisture content and GHGs emissions are positively correlated.

Keywords: soil, GHG emission, sugarcane, agriculture, Thailand

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Authors: S. Wiak, L. Szymanski, Z. Kolacinski, G. Raniszewski, L. Pietrzak, Z. Staniszewska

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The term ‘cancer’ is given to a collection of related diseases that may affect any part of the human body. It is a pathological behaviour of cells with the potential to undergo abnormal breakdown in the processes that control cell proliferation, differentiation, and death of particular cells. Although cancer is commonly considered as modern disease, there are beliefs that drastically growing number of new cases can be linked to the extensively prolonged life expectancy and enhanced techniques for cancer diagnosis. Magnetic hyperthermia therapy is a novel approach to cancer treatment, which may greatly contribute to higher efficiency of the therapy. Employing carbon nanotubes as nanocarriers for magnetic particles, it is possible to decrease toxicity and invasiveness of the treatment by surface functionalisation. Despite appearing in recent years, magnetic particle hyperthermia has already become of the highest interest in the scientific and medical environment. The reason why hyperthermia therapy brings so much hope for future treatment of cancer lays in the effect that it produces in malignant cells. Subjecting them to thermal shock results in activation of numerous degradation processes inside and outside the cell. The heating process initiates mechanisms of DNA destruction, protein denaturation and induction of cell apoptosis, which may lead to tumour shrinkage, and in some cases, it may even cause complete disappearance of cancer. The factors which have the major impact on the final efficiency of the treatment include temperatures generated inside the tissues, time of exposure to the heating process, and the character of an individual cancer cell type. The vast majority of cancer cells is characterised by lower pH, persistent hypoxia and lack of nutrients, which can be associated to abnormal microvasculature. Since in healthy tissues we cannot observe presence of these conditions, they should not be seriously affected by elevation of the temperature. The aim of this work is to investigate the influence of iron content in iron filled Carbon Nanotubes on the desired nanoparticles for cancer therapy. In the article, the development and demonstration of the method and the model device for hyperthermic selective destruction of cancer cells are presented. This method was based on the synthesis and functionalization of carbon nanotubes serving as ferromagnetic material nanocontainers. The methodology of the production carbon- ferromagnetic nanocontainers (FNCs) includes the synthesis of carbon nanotubes, chemical, and physical characterization, increasing the content of a ferromagnetic material and biochemical functionalization involving the attachment of the key addresses. The ferromagnetic nanocontainers were synthesised in CVD and microwave plasma system. The research work has been financed from the budget of science as a research project No. PBS2/A5/31/2013.

Keywords: hyperthermia, carbon nanotubes, cancer colon cells, radio frequency field

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Authors: Rabindranath Jana, Plabani Basu, Keka Rana

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Nucleating agents are widely used to modify the properties of various polymers. The rate of crystallization and the size of the crystals have a strong impact on mechanical and optical properties of a polymer. The addition of nucleating agents to the semi-crystalline polymers provides a surface on which the crystal growth can start easily. As a consequence, fast crystal formation will result in many small crystal domains so that the cycle times for injection molding may be reduced. Moreover, the mechanical properties e.g., modulus, tensile strength, heat distortion temperature and hardness may increase. In the present work, multi-walled carbon nanotubes (MWNTs) as nucleating agents for the crystallization of poly (e-caprolactone)diol (PCL). Thus nanocomposites of PCL filled with MWNTs were prepared by solution blending. Differential scanning calorimetry (DSC) tests were carried out to study the effect of CNTs on on-isothermal crystallization of PCL. The polarizing optical microscopy (POM), and wide-angle X-ray diffraction (WAXD) were used to study the morphology and crystal structure of PCL and its nanocomposites. It is found that MWNTs act as effective nucleating agents that significantly shorten the induction period of crystallization and however, decrease the crystallization rate of PCL, exhibiting a remarkable decrease in the Avrami exponent n, surface folding energy σe and crystallization activation energy ΔE. The carbon-based fillers act as templates for hard block chains of PCL to form an ordered structure on the surface of nanoparticles during the induction period, bringing about some increase in equilibrium temperature. The melting process of PCL and its nanocomposites are also studied; the nanocomposites exhibit two melting peaks at higher crystallization temperature which mainly refer to the melting of the crystals with different crystal sizes however, PCL shows only one melting temperature.

Keywords: poly(e-caprolactone)diol, multiwalled carbon nanotubes, composite materials, nonisothermal crystallization, crystal structure, nucleation

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Authors: Rima Alfaraj, Abeer Alarawi, Murtadha AlTammar

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The global energy landscape heavily relies on the oil and gas industry, which faces the critical challenge of reducing its carbon footprint. To address this issue, the integration of advanced materials like aerogels has emerged as a promising solution to enhance sustainability and environmental performance within the industry. This study thoroughly examines the application of aerogel-based technologies in the oil and gas sector, focusing particularly on their role in carbon capture and storage (CCS) initiatives. Aerogels, known for their exceptional properties, such as high surface area, low density, and customizable pore structure, have garnered attention for their potential in various CCS strategies. The review delves into various fabrication techniques utilized in producing aerogel materials, including sol-gel, supercritical drying, and freeze-drying methods, to assess their suitability for specific industry applications. Beyond fabrication, the practicality of aerogel materials in critical areas such as flow assurance, enhanced oil recovery, and thermal insulation is explored. The analysis spans a wide range of applications, from potential use in pipelines and equipment to subsea installations, offering valuable insights into the real-world implementation of aerogels in the oil and gas sector. The paper also investigates the adsorption and storage capabilities of aerogel-based sorbents, showcasing their effectiveness in capturing and storing carbon dioxide (CO₂) molecules. Optimization of pore size distribution and surface chemistry is examined to enhance the affinity and selectivity of aerogels towards CO₂, thereby improving the efficiency and capacity of CCS systems. Additionally, the study explores the potential of aerogel-based membranes for separating and purifying CO₂ from oil and gas streams, emphasizing their role in the carbon capture and utilization (CCU) value chain in the industry. Emerging trends and future perspectives in integrating aerogel-based technologies within the oil and gas sector are also discussed, including the development of hybrid aerogel composites and advanced functional components to further enhance material performance and versatility. By synthesizing the latest advancements and future directions in aerogel used for CCS applications in the oil and gas industry, this review offers a comprehensive understanding of how these innovative materials can aid in transitioning towards a more sustainable and environmentally conscious energy landscape. The insights provided can assist in strategic decision-making, drive technology development, and foster collaborations among academia, industry, and policymakers to promote the widespread adoption of aerogel-based solutions in the oil and gas sector.

Keywords: CCS, porous, carbon capture, oil and gas, sustainability

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Authors: N. Allouache, W. Elgahri, A. Gahfif, M. Belmedani

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Solar radiation is by far the largest and the most world’s abundant, clean and permanent energy source. The amount of solar radiation intercepted by the Earth is much higher than annual global energy use. The energy available from the sun is greater than about 5200 times the global world’s need in 2006. In recent years, many promising technologies have been developed to harness the sun's energy. These technologies help in environmental protection, economizing energy, and sustainable development, which are the major issues of the world in the 21st century. One of these important technologies is the solar cooling systems that make use of either absorption or adsorption technologies. The solar adsorption cooling systems are a good alternative since they operate with environmentally benign refrigerants that are natural, free from CFCs, and therefore they have a zero ozone depleting potential (ODP). A numerical analysis of thermal and solar performances of an adsorption solar refrigerating system using different adsorbent/adsorbate pairs, such as activated carbon AC35 and activated carbon BPL/Ammoniac; is undertaken in this study. The modeling of the adsorption cooling machine requires the resolution of the equation describing the energy and mass transfer in the tubular adsorber, that is the most important component of the machine. The Wilson and Dubinin- Astakhov models of the solid-adsorbat equilibrium are used to calculate the adsorbed quantity. The porous medium is contained in the annular space, and the adsorber is heated by solar energy. Effect of key parameters on the adsorbed quantity and on the thermal and solar performances are analysed and discussed. The performances of the system that depends on the incident global irradiance during a whole day depends on the weather conditions: the condenser temperature and the evaporator temperature. The AC35/methanol pair is the best pair comparing to the BPL/Ammoniac in terms of system performances.

Keywords: activated carbon-methanol pair, activated carbon-ammoniac pair, adsorption, performance coefficients, numerical analysis, solar cooling system

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Authors: R. Sarjahani, M. Sheikhattar, S. Javadpour, B. Hashemi

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Glazes and their surface characterization is an important subject for ceramic industries. Fabrication of a super smooth surface resistant to stains is a big improvement for those industries. In this investigation, surface topography of popular glazes such as Zircon and Titania based opaque glazes, calcium based matte glaze and transparent glaze has been analyzed by Marsurf M300, SEM, EDS and XRD. Results shows that surface roughness of glazes seriously depends on surface crystallinity, crystal size and shapes.

Keywords: crystallinity, glaze, surface roughness, topography

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Authors: Benyan Jiang, Dawei Xia, Yong Li

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Compact city construction is considered as an effective measure to reduce carbon emission in city lives. Toyama City started its compact city strategy in 2000 and was selected as a Japanese Environmental Model City in 2008 for its achievement. This paper takes Toyama as a study case, aiming to find how city polices affected people’s life styles and reduced carbon emission. The main materials used in this study are first-hand documents, like urban planning materials, government annual report and statistic data from transportation association. It is found that the main measures taken by Toyama City include the construction of light rail transit, increasing the frequency of buses, building park and ride parking lots. In addition to hardware facilities, it also offers flexible policies like passengers' coupons for the senior citizens and free use of parking lots by buying shopping vouchers. Besides, Toyama City encourages citizens to live within 500 meters of public transportation. People who buy an apartment near public transportation will receive 500,000 Japanese Yen. These measures have proven to their effects. Compared with 2005, in 2014, the transportation sector reduced emissions of 2.35 million tons of CO₂, 13.6%. This aspect is related to the increase in the number of cars in public transport and also related to fuel improvement.

Keywords: Toyama, compact city, public transportation, CO₂ reduction

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Authors: Praveen K. Khatri, Neha Karanwal, Savita Kaul, Suman L. Jain

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Conversion of biomass through green chemical routes is of great industrial importance as biomass is considered to be most widely available inexpensive renewable resource that can be used as a raw material for the production of bio fuel and value-added organic products. In this regard, acid catalyzed dehydration of biomass derived pentose sugar (mainly D-xylose) to furfural is a process of tremendous research interest in current scenario due to the wider industrial applications of furfural. Furfural is an excellent organic solvent for refinement of lubricants and separation of butadiene from butene mixture in synthetic rubber fabrication. In addition it also serve as a promising solvent for many organic materials, such as resins, polymers and also used as a building block for synthesis of various valuable chemicals such as furfuryl alcohol, furan, pharmaceutical, agrochemicals and THF. Here in a sulfonated polymer impregnated carbon composite solid acid catalyst (P-C-SO3H) was prepared by the pyrolysis of a polymer matrix impregnated with glucose followed by its sulfonation and used for the dehydration of xylose to furfural. The developed catalyst exhibited excellent activity and provided almost quantitative conversion of xylose with the selective synthesis of furfural. The higher catalytic activity of P-C-SO3H may be due to the more even distribution of polycyclic aromatic hydrocarbons generated from incomplete carbonization of glucose along the polymer matrix network, leading to more available sites for sulfonation which resulted in greater sulfonic acid density in P-C-SO3H as compared to sulfonated carbon catalyst (C-SO3H). In conclusion, we have demonstrated sulfonated polymer impregnated carbon composite (P-C-SO3H) as an efficient and selective solid acid catalyst for the dehydration of xylose to furfural. After completion of the reaction, the catalyst was easily recovered and reused for several runs without noticeable loss in its activity and selectivity.

Keywords: Solid acid , Biomass conversion, Xylose Dehydration, Heterogeneous catalyst

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Authors: Benhui Fan, Fahmi Bedoui, Jinbo Bai

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Incorporated carbon nanotube-BaTiO₃ hybrids (H-CNT-BT) with core-shell structure, a better dispersion of CNTs can be achieved in a semi-crystalline polymeric matrix, polyvinylidene fluoride (PVDF). Carried by BT particles, CNTs are easy to mutually connect which helps to obtain an extremely low percolation threshold (fc). After thermal treatments, the dielectric constants (ε’) of samples further increase which depends on the conditions of thermal treatments such as annealing temperatures, annealing durations and cooling ways. Thus, in order to study more comprehensively about the influence of thermal treatments on composite’s dielectric behaviors, in situ synchrotron X-ray is used to detect re-crystalline behavior of PVDF. Results of wide-angle X-ray diffraction (WAXD) and small-angle X-ray scattering (SAXS) show that after the thermal treatment, the content of β polymorph (the polymorph with the highest ε’ among all the polymorphs of PVDF’s crystalline structure) has increased nearly double times at the interfacial region of CNT-PVDF, and the thickness of amorphous layers (La) in PVDF’s long periods (Lp) has shrunk around 10 Å. The evolution of CNT’s network possibly occurs in the procedure of La shrinkage, where the strong interfacial polarization may be aroused and increases ε’ at low frequency. Moreover, an increase in the thickness of crystalline lamella may also arouse more orientational polarization and improve ε’ at high frequency.

Keywords: dielectric properties, thermal treatments, carbon nanotubes, crystalline structure

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Authors: Sourour Chaabane, Davide Clematis, Marco Panizza

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This study investigates the oxidation of Erythrosine B (EB) food dye by a homogeneous electro-Fenton process using iron (II) sulfate heptahydrate as a catalyst, carbon felt as cathode, and Ti/RuO2. The treated synthetic wastewater contains 100 mg L⁻¹ of EB and has a pH = 3. The effects of three independent variables have been considered for process optimization, such as applied current intensity (0.1 – 0.5 A), iron concentration (1 – 10 mM), and stirring rate (100 – 1000 rpm). Their interactions were investigated considering response surface methodology (RSM) based on Doehlert design as optimization method. EB removal efficiency and energy consumption were considered model responses after 30 minutes of electrolysis. Analysis of variance (ANOVA) revealed that the quadratic model was adequately fitted to the experimental data with R² (0.9819), adj-R² (0.9276) and low Fisher probability (< 0.0181) for EB removal model, and R² (0.9968), adj-R² (0.9872) and low Fisher probability (< 0.0014) relative to the energy consumption model reflected a robust statistical significance. The energy consumption model significantly depends on current density, as expected. The foregoing results obtained by RSM led to the following optimal conditions for EB degradation: current intensity of 0.2 A, iron concentration of 9.397 mM, and stirring rate of 500 rpm, which gave a maximum decolorization rate of 98.15 % with a minimum energy consumption of 0.74 kWh m⁻³ at 30 min of electrolysis.

Keywords: electrofenton, erythrosineb, dye, response serface methdology, carbon felt

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Authors: Mohamed Ayoub

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The structures and energetics of various isomeric hydrogen bonded dimers, such as (FH…OC, FH…CO), (FH…CNH, FH…NCH), (FH…N2O, FH…ON2), and (FH…NHCO, FH…OCNH) have been investigated using DFT B3LYP with aug-cc-pVTZ basis set and by natural bond orbital (NBO) analysis. For each isomeric pair we calculated: H-bond energy (ΔEB…H), charge-transfer (QCT), where B is atom bearing lone-pairs in CO, CNH, NCH, N2O, and NHCO, H-bond distances (RB…H), the elongation of HF bond (ΔRHF) and the red-shift of HF stretching frequency (ΔVHF). We conclude that the principle difference in the relative stability between each isomeric pair is attributed to distinctive interaction of carbon and oxygen lone pairs of CO, carbon and nitrogen lone-pairs of CNH and NCH, and nitrogen and oxygen lone pairs of N2O and NHCO into the unfilled antibond on HF (σ*HF).

Keywords: charge transfer, computational chemistry, isomeric hydrogen bond, natural bond orbital

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Authors: M. E. Ali Mohsin, Agus Arsad, Othman Y. Alothman

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This study explains the influence of secondary filler on the dispersion of carbon nanotube (CNT) reinforced high density polyethylene (HDPE) nanocomposites (CNT/HDPE). In order to understand the mixed-fillers system, Montmorillonite (MMT) was added to CNT/HDPE nanocomposites. It was followed by investigating their effect on the thermal, mechanical and morphological properties of the aforesaid nanocomposite. Incorporation of 3 wt% each of MMT into CNT/HDPE nanocomposite resulted to the increased values for the tensile and flexural strength, as compared to the pure HDPE matrix. The thermal analysis result showed improved thermal stability of the formulated nanocomposites. Transmission electron microscopy (TEM) images revealed that larger aggregates of CNTs were disappeared upon addition of these two components leading to the enhancement of thermo-mechanical properties for such composites.

Keywords: secondary filler, montmorillonite, carbon nanotube, nanocomposite

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Authors: Nadia Allouache, Omar Rahli

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Many promising technologies have been developed to harness the sun's energy. These technologies help in economizing energy and environmental protection. The solar refrigerating systems are one of these important technologies. In addition to environmental benefits and energy saving, adsorption refrigerating systems have many advantages such as lack of moving parts, simplicity of construction and low operating costs. The work aimed to establish the main factors that affect the performances of an adsorption refrigerating system using different geometries of adsorbers and different adsorbent-adsorbate pairs. The numerical modeling of the heat and mass transfer in the system, using various working pairs, such as: activated carbon-ammonia, calcium chlorid-ammonia, activated carbon fiber- methanol and activated carbon AC35-methanol, show that the adsorber design can influence the system performances; The thermal performances of system are better in the annular configuration case. An optimal value of generating temperature is observed in annular adsorber case for which the thermal performance of the cooling system is maximal. While in the plate adsorber, above a certain value of generating temperature, the performance of the system remains almost constant. The environmental conditions such as solar radiation and pressure have a great influence in the system efficiency, and the choice of the working pair depends on the environmental conditions and the geometry of the adsorber.

Keywords: adsorber geometry, numerical modeling, optimal environmental conditions, working pairs.

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Authors: Mohsen Adabi, Mahdi Adabi, Reza Saber

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The recent advancements in nanomaterials have provided a platform to develop efficient transduction matrices for sensors. Modified electrodes allow to electrochemists to enhance the property of electrode surface and provide desired properties such as improved sensing capabilities, higher electron transfer rate and prevention of undesirable reactions competing kinetically with desired electrode process. Nanostructured electrodes including arrays of carbon nanotubes have demonstrated great potential for the development of electrochemical sensors and biosensors. The aim of this work is to evaluate the concentration of multi-walled carbon nanotubes (MWCNTs) on the conductivity of gold electrode. For this work, raw MWCNTs was functionalized and shortened. Raw and shorten MWCNTs were characterized using transfer electron microscopy (TEM). Next, 0.5, 2 and 3.5 mg of Shortened and functionalized MWCNTs were dispersed in 2 mL Dimethyl formamide (DMF) and cysteamine modified gold electrodes were incubated in the different concentrations of MWCNTs for 8 hours. Then, the immobilization of MWCNTs on cysteamine modified gold electrode was characterized by scanning electron microscopy (SEM) and the effect of MWCNT concentrations on electron transfer of modified electrodes was investigated by cyclic voltammetry (CV). The results demonstrated that CV response of ferricyanide redox at modified gold electrodes increased as concentration of MWCNTs enhanced from 0.5 to 2 mg in 2 mL DMF. This increase can be attributed to the number of MWCNTs which enhance on the surface of cysteamine modified gold electrode as the MWCNTs concentration increased whereas CV response of ferricyanide redox at modified gold electrodes did not changed significantly as the MWCNTs concentration increased from 2 to 3.5 mg in 2 mL DMF. The reason may be that amine groups of cysteamine modified gold electrodes are limited to a given number which can interact with the given number of carboxylic groups of MWCNTs and CV response of ferricyanide redox at modified gold do not enhance after amine groups of cysteamine are saturated with carboxylic groups of MWCNTs.

Keywords: carbon nanotube, cysteamine, electrochemical sensor, gold electrode

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Authors: Shasline Gedeon, Tiffany W. Ardley, Ying Wang, Nathan J. Gesmundo, Katarina A. Sarris, Ana L. Aguirre

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Drug discovery and delivery involve drug targeting, an approach that helps find a drug against a chosen target through high throughput screening and other methods by way of identifying the physical properties of the potential lead compound. Physical properties of potential drug candidates have been an imperative focus since the unveiling of Lipinski's Rule of 5 for oral drugs. Throughout a compound's journey from discovery, clinical phase trials, then becoming a classified drug on the market, the desirable properties are optimized while minimizing/eliminating toxicity and undesirable properties. In the pharmaceutical industry, the ability to generate molecules in parallel with maximum efficiency is a substantial factor achieved through sp²-sp² carbon coupling reactions, e.g., Suzuki Coupling reactions. These reaction types allow for the increase of aromatic fragments onto a compound. More recent literature has found benefits to decreasing aromaticity, calling for more sp³-sp² carbon coupling reactions instead. The objective of this project is to provide a comparison between various sp³-sp² carbon coupling methods and reaction conditions, collecting data on production of the desired product. There were four different coupling methods being tested amongst three cores and 4-5 installation groups per method; each method ran under three distinct reaction conditions. The tested methods include the Photoredox Decarboxylative Coupling, the Photoredox Potassium Alkyl Trifluoroborate (BF3K) Coupling, the Photoredox Cross-Electrophile (PCE) Coupling, and the Weix Cross-Electrophile (WCE) Coupling. The results concluded that the Decarboxylative method was very difficult in yielding product despite the several literature conditions chosen. The BF3K and PCE methods produced competitive results. Amongst the two Cross-Electrophile coupling methods, the Photoredox method surpassed the Weix method on numerous accounts. The results will be used to build future libraries.

Keywords: drug discovery, high throughput chemistry, photoredox chemistry, sp³-sp² carbon coupling methods

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Authors: Kwok W. Mui, Ling T. Wong, F. Xiao, Chin T. Cheung, Ho C. Yu

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This study addresses a concept of the Sustainable Building Environmental Model (SBEM) developed to optimize energy consumption in air conditioning and ventilation (ACV) systems without any deterioration of indoor environmental quality (IEQ). The SBEM incorporates two main components: an adaptive comfort temperature control module (ACT) and a new carbon dioxide demand control module (nDCV). These two modules take an innovative approach to maintain satisfaction of the Indoor Environmental Quality (IEQ) with optimum energy consumption, they provide a rational basis of effective control. A total of 2133 sets of measurement data of indoor air temperature (Ta), relative humidity (Rh) and carbon dioxide concentration (CO2) were conducted in some Hong Kong offices to investigate the potential of integrating the SBEM. A simulation was used to evaluate the dynamic performance of the energy and air conditioning system with the integration of the SBEM in an air-conditioned building. It allows us make a clear picture of the control strategies and performed any pre-tuned of controllers before utilized in real systems. With the integration of SBEM, it was able to save up to 12.3% in simulation and 15% in field measurement of overall electricity consumption, and maintain the average carbon dioxide concentration within 1000ppm and occupant dissatisfaction in 20%.

Keywords: sustainable building environmental model (SBEM), adaptive comfort temperature (ACT), new demand control ventilation (nDCV), energy saving

Procedia PDF Downloads 636

Authors: Maryam Siyami

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Zero energy buildings refer to buildings that have zero annual energy consumption and do not produce carbon emissions. In today's world, considering the limited resources of fossil fuels, buildings, industries and other organizations have moved towards using other available energies. The idea and principle of net zero energy consumption has attracted a lot of attention because the use of renewable energy is a means and a solution to eliminate pollutants and greenhouse gases. Due to the increase in the cost of fossil fuels and their destructive effects on the environment and disrupting the ecological balance, today the plans related to zero energy principles have become very practical and have gained particular popularity. In this research, building modeling has been done in the Design Builder software environment. Based on the changes in the required energy throughout the year in different roof thickness conditions, it has been observed that with the increase in roof thickness, the amount of heating energy required has a downward trend, from 6730 kilowatt hours in the roof thickness of 10 cm to 6408 kilowatt hours in the roof thickness condition. 20 cm is reached, which represents a reduction of about 4.7% in energy if the roof thickness is doubled. Also, with the increase in the thickness of the roof throughout the year, the amount of cooling energy required has a gentle downward trend and has reached from 4964 kilowatt hours in the case of a roof thickness of 10 cm to 4859 kilowatt hours in the case of a roof thickness of 20 cm, which is a decrease equal to It displays 2%. It can be seen that the trend of changes in the energy required for cooling and heating is not much affected by the thickness of the roof (with an effect of 98%) and therefore there is no technical and economic recommendation to increase the thickness of the roof in this sector. Finally, based on the changes in the carbon dioxide produced in different states of the roof thickness, it has been observed that with the increase in the roof thickness, energy consumption and consequently the production of carbon dioxide has decreased. By increasing the thickness of the roof from 10 cm to 20 cm, the amount of carbon dioxide produced by heating the building has decreased by 27%. Also, this amount of reduction has been obtained based on the cooling system and for different amounts of roof thickness equal to 19%.

Keywords: energy consumption, green building, design builder, AHP

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Authors: Talal Hasan, Akram Mohammad

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Carbon-free combustion has great attention in today’s research for its unlimited benefits regarding various factors, and ammonia is considered a potential carbon-free alternative gas despite its flame characteristics. The Shrestha mechanism and Chemkin-Pro software will be used for numerical data. Firstly, experimental and numerical results should show good agreement to move for studying the laminar flame speed of ammonia under various conditions. Ammonia flame speed will be investigated under normal conditions (298 K, 1 atm) as well as under the influence of a range of equivalence ratios (0.6-1.8), elevated temperatures (298,323,373,423, and 473), elevated pressures (1 atm- 70 atm) and finally at varying hydrogen content (0-100%). Therefore, this work will understand the ammonia laminar flame speed characteristics and how and to what extent hydrogen can improve ammonia combustion intensity.

Keywords: laminar burning velocity, ammonia, hydrogen, combustion

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Authors: Y. T. Gebreslassie, Abrha Tadesse, R. C. Saini, Rishi Pal

Abstract:

Caffeine, known chemically as 3,7-dihydro-1,3,7-trimethyl-1H-purine-2,6-dione, is a naturally occurring alkaloid classified as an N-methyl derivative of xanthine. Given its widespread use in coffee and other caffeine-containing products, it is the most commonly consumed psychoactive substance in everyday human life. This research aimed to develop a cost-effective, sensitive, and easily manufacturable sensor for the detection of caffeine. Antraquinone-modified carbon paste electrode (AQMCPE) was fabricated, and the electrochemical behavior of caffeine on this electrode was investigated using cyclic voltammetry (CV) and square wave voltammetry (SWV) in a solution of 0.1M perchloric acid at pH 0.56. The modified electrode displayed enhanced electrocatalytic activity towards caffeine oxidation, exhibiting a two-fold increase in peak current and an 82 mV shift of the peak potential in the negative direction compared to an unmodified carbon paste electrode (UMCPE). Exploiting the electrocatalytic properties of the modified electrode, SWV was employed for the quantitative determination of caffeine. Under optimized experimental conditions, a linear relationship between peak current and concentration was observed within the range of 2.0 x 10⁻⁶ to 1.0× 10⁻⁴ M, with a correlation coefficient of 0.998 and a detection limit of 1.47× 10⁻⁷ M (signal-to-noise ratio = 3). Finally, the proposed method was successfully applied to the quantitative analysis of caffeine in pharmaceutical formulations, yielding recovery percentages ranging from 95.27% to 106.75%.

Keywords: antraquinone-modified carbon paste electrode, caffeine, detection, electrochemical sensor, quantitative analysis

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