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A novel approach to environmental pollution management/remediation techniques using derived advanced materials

Singh R, Samuel MS, Ravikumar M, Ethiraj S, Kirankumar VS, Kumar M, et al.

Chemosphere, 2023 Dec;344:140311.
PMID: 37769916 DOI: 10.1016/j.chemosphere.2023.140311

The carbon dioxide (CO2) crisis is one of the world's most urgent issues. Meeting the worldwide targets set for CO2 capture and storage (CCS) is crucial. Because it may significantly reduce energy consumption compared to traditional amine-based adsorption capture, adsorption dependant CO2 capture is regarded as one of the most hopeful techniques in this paradigm. The expansion of unique, critical edge adsorbent materials has received most of the research attention to date, with the main objective of improving adsorption capacity and lifespan while lowering the temperature of adsorption, thereby lowering the energy demand of sorbent revival. There are specific materials needed for each step of the carbon cycle, including capture, regeneration, and conversion. The potential and efficiency of metal-organic frameworks (MOFs) in overcoming this obstacle have recently been proven through research. In this study, we pinpoint MOFs' precise structural and chemical characteristics that have contributed to their high capture capacity, effective regeneration and separation processes, and efficient catalytic conversions. As prospective materials for the next generation of energy storage and conversion applications, carbon-based compounds like graphene, carbon nanotubes, and fullerenes are receiving a lot of interest. Their distinctive physicochemical characteristics make them suitable for these popular study topics, including structural stability and flexibility, high porosity, and customizable physicochemical traits. It is possible to precisely design the interior of MOFs to include coordinatively unsaturated metal sites, certain heteroatoms, covalent functionalization, various building unit interactions, and integrated nanoscale metal catalysts. This is essential for the creation of MOFs with improved performance. Utilizing the accuracy of MOF chemistry, more complicated materials must be built to handle selectivity, capacity, and conversion all at once to achieve a comprehensive solution. This review summarizes, the most recent developments in adsorption-based CO2 combustion capture, the CO2 adsorption capacities of various classes of solid sorbents, and the significance of advanced carbon nanomaterials for environmental remediation and energy conversion. This review also addresses the difficulties and potential of developing carbon-based electrodes for energy conversion and storage applications.

Matched MeSH terms: Carbon Dioxide/chemistry
The Application of Graphene and Its Derivatives to Energy Conversion, Storage, and Environmental and Biosensing Devices

Ali Tahir A, Ullah H, Sudhagar P, Asri Mat Teridi M, Devadoss A, Sundaram S

Chem Rec, 2016 06;16(3):1591-634.
PMID: 27230414 DOI: 10.1002/tcr.201500279

Graphene (GR) and its derivatives are promising materials on the horizon of nanotechnology and material science and have attracted a tremendous amount of research interest in recent years. The unique atom-thick 2D structure with sp(2) hybridization and large specific surface area, high thermal conductivity, superior electron mobility, and chemical stability have made GR and its derivatives extremely attractive components for composite materials for solar energy conversion, energy storage, environmental purification, and biosensor applications. This review gives a brief introduction of GR's unique structure, band structure engineering, physical and chemical properties, and recent energy-related progress of GR-based materials in the fields of energy conversion (e.g., photocatalysis, photoelectrochemical water splitting, CO2 reduction, dye-sensitized and organic solar cells, and photosensitizers in photovoltaic devices) and energy storage (batteries, fuel cells, and supercapacitors). The vast coverage of advancements in environmental applications of GR-based materials for photocatalytic degradation of organic pollutants, gas sensing, and removal of heavy-metal ions is presented. Additionally, the use of graphene composites in the biosensing field is discussed. We conclude the review with remarks on the challenges, prospects, and further development of GR-based materials in the exciting fields of energy, environment, and bioscience.

Matched MeSH terms: Carbon Dioxide/chemistry
Mapping the field of microalgae CO2 sequestration: a bibliometric analysis

Ren H, Zhou D, Lu J, Show PL, Sun FF

Environ Sci Pollut Res Int, 2023 Jul;30(32):78030-78040.
PMID: 37311860 DOI: 10.1007/s11356-023-27850-0

Microalgae CO2 sequestration has gained considerable attention in the last three decades as a promising technology to slow global warming caused by CO2 emissions. To provide a comprehensive and objective analysis of the research status, hot spots, and frontiers of CO2 fixation by microalgae, a bibliometric approach was recently chosen for review. In this study, 1561 articles (1991-2022) from the Web of Science (WOS) on microalgae CO2 sequestration were screened. A knowledge map of the domain was presented using VOSviewer and CiteSpace. It visually demonstrates the most productive journals (Bioresource Technology), countries (China and USA), funding sources, and top contributors (Cheng J, Chang JS, and their team) in the field of CO2 sequestration by microalgae. The analysis also revealed that research hotspots changed over time and that recent research has focused heavily on improving carbon sequestration efficiency. Finally, commercialization of carbon fixation by microalgae is a key hurdle, and supports from other disciplines could improve carbon sequestration efficiency.

Matched MeSH terms: Carbon Dioxide*
On-line CO, CO2 emissions evaluation and (benzene, toluene, xylene) determination from experimental burn of tropical biomass

Tawfiq MF, Aroua MK, Sulaiman NM

J Environ Sci (China), 2015 Jul 1;33:239-44.
PMID: 26141898 DOI: 10.1016/j.jes.2015.01.015

Atmospheric pollution and global warming issues are increasingly becoming major environmental concerns. Fire is one of the significant sources of pollutant gases released into the atmosphere; and tropical biomass fires, which are of particular interest in this study, contribute greatly to the global budget of CO and CO2. This pioneer research simulates the natural biomass burning strategy in Malaysia using an experimental burning facility. The investigation was conducted on the emissions (CO2, CO, and Benzene, Toluene, Ethylbenzene, Xylenes (BTEX)) from ten tropical biomass species. The selected species represent the major tropical forests that are frequently subjected to dry forest fire incidents. An experimental burning facility equipped with an on-line gas analyzer was employed to determine the burning emissions. The major emission factors were found to vary among the species, and the specific results were as follows. The moisture content of a particular biomass greatly influenced its emission pattern. The smoke analysis results revealed the existence of BTEX, which were sampled from a combustion chamber by enrichment traps aided with a universal gas sampler. The BTEX were determined by organic solvent extraction followed by GC/MS quantification, the results of which suggested that the biomass burning emission factor contributed significant amounts of benzene, toluene, and m,p-xylene. The modified combustion efficiency (MCE) changed in response to changes in the sample moisture content. Therefore, this study concluded that the emission of some pollutants mainly depends on the burning phase and sample moisture content of the biomass.

Matched MeSH terms: Carbon Dioxide/chemistry*
Moderating effect of governance on healthcare and environmental emissions

Subramaniam Y, Loganathan N, Subramaniam T

J Environ Manage, 2024 Feb;351:119646.
PMID: 38042078 DOI: 10.1016/j.jenvman.2023.119646

Governance has become indispensable within the healthcare sector, but previous studies have not explored the potential environmental benefits linked to healthcare governance. Thus, this study focuses on the role of governance in moderating healthcare and environmental emissions in 159 low, lower-middle, upper-middle and high-income countries. To do so, cross-sectional autoregressive distributed lag (CS-ARDL) techniques were applied using panel data from 1999 to 2021, followed by the computation of threshold and marginal effect of governance on healthcare and environmental emissions nexus. Findings revealed that, with the exception of high-income countries in the short run, governance has an insignificant impact on healthcare and emissions nexus in low-, lower-middle and upper-middle-income countries. Surprisingly, the findings imply that, in the long run, countries with greater levels of governance are likely to have lesser environmental impacts related to healthcare. There was also evidence indicating that low, lower-middle, upper-middle and high-income countries must reach a certain level of governance before realising the benefits of healthcare. Therefore, to achieve lower environmental impacts from healthcare, countries must promote effective governance policies that can incentivise and enforce sustainable practices and technologies in the healthcare sector.

Matched MeSH terms: Carbon Dioxide*
Fulltext Continuous-flow Heck synthesis of 4-methoxybiphenyl and methyl 4-methoxycinnamate in supercritical carbon dioxide expanded solvent solutions

Lau PL, Allen RW, Styring P

Beilstein J Org Chem, 2013;9:2886-97.
PMID: 24367454 DOI: 10.3762/bjoc.9.325

The palladium metal catalysed Heck reaction of 4-iodoanisole with styrene or methyl acrylate has been studied in a continuous plug flow reactor (PFR) using supercritical carbon dioxide (scCO2) as the solvent, with THF and methanol as modifiers. The catalyst was 2% palladium on silica and the base was diisopropylethylamine due to its solubility in the reaction solvent. No phosphine co-catalysts were used so the work-up procedure was simplified and the green credentials of the reaction were enhanced. The reactions were studied as a function of temperature, pressure and flow rate and in the case of the reaction with styrene compared against a standard, stirred autoclave reaction. Conversion was determined and, in the case of the reaction with styrene, the isomeric product distribution was monitored by GC. In the case of the reaction with methyl acrylate the reactor was scaled from a 1.0 mm to 3.9 mm internal diameter and the conversion and turnover frequency determined. The results show that the Heck reaction can be effectively performed in scCO2 under continuous flow conditions with a palladium metal, phosphine-free catalyst, but care must be taken when selecting the reaction temperature in order to ensure the appropriate isomer distribution is achieved. Higher reaction temperatures were found to enhance formation of the branched terminal alkene isomer as opposed to the linear trans-isomer.

Matched MeSH terms: Carbon Dioxide
Non-native mangroves support carbon storage, sediment carbon burial, and accretion of coastal ecosystems

Soper FM, MacKenzie RA, Sharma S, Cole TG, Litton CM, Sparks JP

Glob Chang Biol, 2019 Aug 29.
PMID: 31465581 DOI: 10.1111/gcb.14813

Mangrove forests play an important role in climate change adaptation and mitigation by maintaining coastline elevations relative to sea level rise, protecting coastal infrastructure from storm damage and storing substantial quantities of carbon (C) in live and detrital pools. Determining the efficacy of mangroves in achieving climate goals can be complicated by difficulty in quantifying C inputs (i.e., differentiating newer inputs from younger trees from older residual C pools), and mitigation assessments rarely consider potential offsets to CO2 storage by methane (CH4 ) production in mangrove sediments. The establishment of non-native Rhizophora mangle along Hawaiian coastlines over the last century offers an opportunity to examine the role mangroves play in climate mitigation and adaptation both globally and locally as novel ecosystems. We quantified total ecosystem C storage, sedimentation, accretion, sediment organic C burial and CH4 emissions from ~70 year old R. mangle stands and adjacent uninvaded mudflats. Ecosystem C stocks of mangrove stands exceeded mudflats by 434 ± 33 Mg C ha-1 , and mangrove establishment increased average coastal accretion by 460%. Sediment organic C burial increased 10-fold (to 4.5 Mg C ha-1 yr-1 ), double the global mean for old growth mangrove forests, suggesting that C accumulation from younger trees may occur faster than previously thought, with implications for mangrove restoration. Simulations indicate that increased CH4 emissions from sediments offset ecosystem CO2 storage by only 2-4%, equivalent to 30-60 Mg CO2 -eq ha-1 over mangrove lifetime (100-year sustained global warming potential). Results highlight the importance of mangroves as novel systems that can rapidly accumulate C, have a net positive atmospheric greenhouse gas removal effect, and support shoreline accretion rates that outpace current sea level rise. Sequestration potential of novel mangrove forests should be taken into account when considering their removal or management, especially in the context of climate mitigation goals.

Matched MeSH terms: Carbon Dioxide
Fulltext A thermodynamic equilibrium analysis on oxidation of methane to higher hydrocarbons

Nor Aishah Saidina Amin, Soon, Ee Peng

Pertanika Journal of Science & Technology, 2009;17(2):-.
MyJurnal

Thermodynamic chemical equilibrium analysis using, total Gibbs energy minimization method, was carried out for methane oxidation to higher hydrocarbons. For a large methane conversion and a high selectivity to higher hydrocarbons, the system temperature and oxygen concentration played a vital role, whereas, the system pressure only slightly influenced the two variables. Numerical results showed that the conversion of methane increased with the concentration of oxygen and reaction temperature, but it decreased with pressure. Nevertheless, the presence of oxygen suppressed the formation of higher hydrocarbons which mostly consisted of aromatics, but enhanced the formation of hydrogen. As the system pressure increased, the aromatics, olefins and hydrogen yields diminished, but the paraffin yield improved. Carbon monoxide seemed to be the major oxygen-containing equilibrium product from methane oxidation, whilst almost no H2O, CH3OH and HCOH were detected although traces amount of carbon dioxide were formed at relatively lower temperature and higher pressure. The total Gibbs energy minimization method is useful to theoretically analyze the feasibility of methane conversion to higher hydrocarbons and syngas at the selected temperature and pressure.

Matched MeSH terms: Carbon Dioxide
Unveiling the non-linear impact of sectoral output on environmental pollution in Malaysia

Ehigiamusoe KU, Lean HH, Somasundram S

Environ Sci Pollut Res Int, 2022 Jan;29(5):7465-7488.
PMID: 34476686 DOI: 10.1007/s11356-021-16114-4

This paper investigates the non-linear impacts of the agricultural, industrial, financial, and service sectors on environmental pollution in Malaysia during the 1980-2018 period. It employs the extended STIRPAT model and two indicators of environmental pollution (carbon dioxide emissions and ecological footprints). It uses the autoregressive distributed lag (ARDL) technique to estimate the parameters. Evidence from the study indicate that the agricultural, industrial, and service sectors have inverted U-shaped non-linear impacts on carbon dioxide emissions and ecological footprints, while the financial sector has a U-shaped non-linear relationship with carbon dioxide emissions and ecological footprint. These empirical outcomes are robust to diagnostic tests, structural breaks, and alternative estimation technique and proxies. The economic implication of this paper is that, at the early stage of sectoral growth, the pollution intensity of sectoral output increases, but after a certain turning point, a further increase in sectoral output will reduce environmental pollution. Precisely, environmental pollution will reduce if the agricultural, industrial, and service sectors exceed threshold levels of 11%, 44%, and 49% of GDP, respectively, while environmental pollution will be aggravated if financial sector exceeds a threshold level of 94%. Therefore, efforts to mitigate environmental pollution in Malaysia should integrate sectoral growth to attain sustainable development.

Matched MeSH terms: Carbon Dioxide/analysis
Antioxidant activity of Piper nigrum L. essential oil extracted by supercritical CO₂ extraction and hydro-distillation

Bagheri H, Abdul Manap MY, Solati Z

Talanta, 2014 Apr;121:220-8.
PMID: 24607131 DOI: 10.1016/j.talanta.2014.01.007

The aim of this study was to optimize the antioxidant activity of Piper nigrum L. essential oil extracted using the supercritical carbon dioxide (SC-CO₂) technique. Response surface methodology was applied using a three-factor central composite design to evaluate the effects of three independent extraction variables: pressure of 15-30 MPa, temperature of 40-50 °C and dynamic extraction time of 40-80 min. The DPPH radical scavenging method was used to evaluate the antioxidant activity of the extracts. The results showed that the best antioxidant activity was achieved at 30 MPa, 40 °C and 40 min. The extracts were analyzed by GC-FID and GC-MS. The main components extracted using SC-CO₂ extraction in optimum conditions were β-caryophyllene (25.38 ± 0.62%), limonene (15.64 ± 0.15%), sabinene (13.63 ± 0.21%), 3-carene (9.34 ± 0.04%), β-pinene (7.27 ± 0.05%), and α-pinene (4.25 ± 0.06%). The essential oil obtained through this technique was compared with the essential oil obtained using hydro-distillation. For the essential oil obtained by hydro-distillation, the most abundant compounds were β-caryophyllene (18.64 ± 0.84%), limonene (14.95 ± 0.13%), sabinene (13.19 ± 0.17%), 3-carene (8.56 ± 0.11%), β-pinene (9.71 ± 0.12%), and α-pinene (7.96 ± 0.14%). Radical scavenging activity of the extracts obtained by SC-CO₂ and hydro-distillation showed an EC₅₀ of 103.28 and 316.27 µg mL(-1) respectively.

Matched MeSH terms: Carbon Dioxide/analysis*
Convergence in CO 2 emissions, carbon footprint and ecological footprint: evidence from OECD countries

Solarin SA

Environ Sci Pollut Res Int, 2019 Feb;26(6):6167-6181.
PMID: 30617875 DOI: 10.1007/s11356-018-3993-8

The aim of this paper is to augment the existing literature on convergence of CO2 emissions, by adding carbon footprint per capita and ecological footprint per capita to the convergence debate. We use the residual augmented least squares regression to examine the stochastic convergence of the environmental indices in 27 OECD countries. Furthermore, in contrast to the previous studies which mainly used the conventional beta-convergence approach to examine conditional convergence, we use a beta-convergence method that is capable of identifying the actual number of countries that contribute to conditional convergence. The sigma-convergence of the environmental indices is also examined. The results suggest that conditional convergence exists in 12 countries for CO2 emissions per capita, 15 countries for carbon footprint per capita and also 13 countries for ecological footprint per capita. There is evidence for sigma-convergence for all the three indicators. The policy implications of the results are discussed in the body of the paper.

Matched MeSH terms: Carbon Dioxide
Stochastic convergence in carbon emissions based on a new Fourier-based wavelet unit root test

Erdogan S, Solarin SA

Environ Sci Pollut Res Int, 2021 May;28(17):21887-21899.
PMID: 33410083 DOI: 10.1007/s11356-020-12033-y

Most of the existing studies on stochastic convergence of emission have not adequately considered smooth structural changes. The primary purpose of this paper is to examine the validity of stochastic convergence at different income levels by recently proposed Fourier-based wavelet augmented Dickey-Fuller test with smooth shifts. Empirical results can be summed up as follows: (i) carbon emission per capita follows the stationarity process in 35 high-income countries, while carbon emission per capita follows the stationarity process in 27 upper-middle-income countries; (ii) besides, carbon emission per capita follows stationarity process in 30 lower-middle-income countries, while carbon emission per capita follows stationarity process in 13 low-income countries; (iii) in light of these findings, it can be said that stochastic convergence among different income groups is valid. The implications of the empirical findings for environmental planning and management are discussed in the body of the paper.

Matched MeSH terms: Carbon Dioxide*
Potentially malignant disorders revisited-The lichenoid lesion/proliferative verrucous leukoplakia conundrum

Thomson PJ, Goodson ML, Smith DR

J Oral Pathol Med, 2018 Jul;47(6):557-565.
PMID: 29663518 DOI: 10.1111/jop.12716

BACKGROUND: Clinically identifiable potentially malignant disorders (PMD) precede oral squamous cell carcinoma development. Oral lichenoid lesions (OLL) and proliferative verrucous leukoplakia (PVL) are specific precursor lesions believed to exhibit both treatment resistance and a high risk of malignant transformation (MT).
METHODS: A retrospective review of 590 PMD patients treated in Northern England by CO2 laser surgery between 1996 and 2014 was carried out. Lesions exhibiting lichenoid or proliferative verrucous features were identified from the patient database and their clinicopathological features and outcome post-treatment determined at the study census date of 31 December 2014.
RESULTS: One hundred and 98 patients were identified as follows: 118 OLL and 80 PVL, most frequently leukoplakia at ventrolateral tongue and floor of mouth sites, equally distributed between males and females. Most exhibited dysplasia on incision biopsy (72% OLL; 85% PVL) and were treated by laser excision rather than ablation (88.1% OLL; 86.25% PVL). OLL were more common in younger patients (OLL 57.1 year; PVL 62.25 years; P = .008) and more likely than PVL to present as erythroleukoplakia (OLL 15.3%; PVL 2.5%; P = .003). Whilst no significant difference was seen between OLL and PVL achieving disease-free status (69.5% and 65%, respectively; P = .55), this was less than the overall PMD cohort (74.2%). MT was identified in 2 OLL (1.7%) and 2 PVL (2.5%) during follow-up.
CONCLUSION: One-third of PMD cases showed features of OLL or PVL, probably representing a disease presentation continuum. Post-treatment disease-free status was less common in OLL and PVL, although MT was infrequent.

Matched MeSH terms: Carbon Dioxide
Are secondary forests second-rate? Comparing peatland greenhouse gas emissions, chemical and microbial community properties between primary and secondary forests in Peninsular Malaysia

Dhandapani S, Ritz K, Evers S, Yule CM, Sjögersten S

Sci Total Environ, 2019 Mar 10;655:220-231.
PMID: 30471590 DOI: 10.1016/j.scitotenv.2018.11.046

Tropical peatlands are globally important ecosystems with high C storage and are endangered by anthropogenic disturbances. Microbes in peatlands play an important role in sustaining the functions of peatlands as a C sink, yet their characteristics in these habitats are poorly understood. This research aimed to elucidate the responses of these complex ecosystems to disturbance by exploring greenhouse gas (GHG) emissions, nutrient contents, soil microbial communities and the functional interactions between these components in a primary and secondary peat swamp forest in Peninsular Malaysia. GHG measurements using closed chambers, and peat sampling were carried out in both wet and dry seasons. Microbial community phenotypes and nutrient content were determined using phospholipid fatty acid (PLFA) and inductively-coupled plasma mass spectrometry (ICP-MS) analyses respectively. CO2 emissions in the secondary peat swamp forest were > 50% higher than in the primary forest. CH4 emission rates were ca. 2 mg m-2 h-1 in the primary forest but the secondary forest was a CH4 sink, showing no seasonal variations in GHG emissions. Almost all the nutrient concentrations were significantly lower in the secondary forest, postulated to be due to nutrient leaching via drainage and higher rates of decomposition. Cu and Mo concentrations were negatively correlated with CO2 and CH4 emissions respectively. Microbial community structure was overwhelmingly dominated by bacteria in both forest types, however it was highly sensitive to land-use change and season. Gram-positive and Gram-negative relative abundance were positively correlated with CO2 and CH4 emissions respectively. Drainage related disturbances increased CO2 emissions, by reducing the nutrient content including some with known antimicrobial properties (Cu & Na) and by favouring Gram-positive bacteria over Gram-negative bacteria. These results suggest that the biogeochemistry of secondary peat swamp forest is fundamentally different from that of primary peat swamp forest, and these differences have significant functional impacts on their respective environments.

Matched MeSH terms: Carbon Dioxide/analysis*
Fulltext Greenhouse gas emissions resulting from conversion of peat swamp forest to oil palm plantation

Cooper HV, Evers S, Aplin P, Crout N, Dahalan MPB, Sjogersten S

Nat Commun, 2020 01 21;11(1):407.
PMID: 31964892 DOI: 10.1038/s41467-020-14298-w

Conversion of tropical peat swamp forest to drainage-based agriculture alters greenhouse gas (GHG) production, but the magnitude of these changes remains highly uncertain. Current emissions factors for oil palm grown on drained peat do not account for temporal variation over the plantation cycle and only consider CO2 emissions. Here, we present direct measurements of GHGs emitted during the conversion from peat swamp forest to oil palm plantation, accounting for CH4 and N2O as well as CO2. Our results demonstrate that emissions factors for converted peat swamp forest is in the range 70-117 t CO2 eq ha-1 yr-1 (95% confidence interval, CI), with CO2 and N2O responsible for ca. 60 and ca. 40% of this value, respectively. These GHG emissions suggest that conversion of Southeast Asian peat swamp forest is contributing between 16.6 and 27.9% (95% CI) of combined total national GHG emissions from Malaysia and Indonesia or 0.44 and 0.74% (95% CI) of annual global emissions.

Matched MeSH terms: Carbon Dioxide/analysis; Carbon Dioxide/metabolism
Fulltext CHARACTERISTIC OF PRASEODYMIUM OXIDE DOPED MANGANESE/RUTHENIUM CATALYST IN METHANATION: EFFECT CALCINATION TEMPERATURE

Salmiah Jamal Mat Rosid, Susilawati Toemen, Wan Azelee Wan Abu Bakar, Sarina Mat Rosid, Wan Nazwanie Wan Abdullah, Siti Maisarah Aziz

Journal of Academia Universiti Teknologi MARA Negeri Sembilan, 2021;9(1):49-55.
MyJurnal

Lanthanide element in the methanation reaction gives an excellent catalytic performance at low reaction temperature. Praseodymium is one of lanthanide element and was chosen due to its properties which are thermally stable and provide excess of oxygen in the oxide lattice. Therefore, a catalyst of Ru/Mn/Pr (5:30:65)/Al2O3 (RMP, 5:30:65/Al2O3) was prepared via wetness impregnation method and the effect of calcination temperature on the catalyst performance was investigated using FTIR analysis. The RMP/Al2O3 catalyst calcined at 800 o C was chosen as an excel catalyst with CO2 conversion of 96.9% and CH4 formation of 45.1% at 350 o C reaction temperature. From the EDX mapping, it can be observed that the distribution of all element is homogeneous at 800 o C and 900 o C except Ru, O and Al at 1000 o C calcination temperature. The image from FESEM also shows the presence of some crystal shape on the catalyst surface. From the FTIR analysis, the peak stretching and bending mode of O-H bond decreased when the calcination temperature increased.

Matched MeSH terms: Carbon Dioxide
Fulltext Development of supercritical fluid extraction for the recovery of betacyanins from red pitaya fruit (Hylocereus polyrhizus) peel: a source of natural red pigment with potential antioxidant properties

Fathordoobady, F., Manap, M.Y., Selamat, J., Singh, A.P.

International Food Research Journal, 2019;26(3):1023-1034.
MyJurnal

In the present work, supercritical fluid extraction (SFE) with CO2 as solvent and EtOH/water (v/v) as co-solvent was optimised by applying 23 factorial experimental design for the extraction of betacyanins from red pitaya fruit (Hylocereus polyrhizus) peel. Three independent variables of pressure (20-30 MPa), temperature (40-60°C) and co-solvent concentration (10-20%) were chosen for response variables. With the 2 mL/min flow rate of CO2, the dynamic time of extraction was found to be 90 min. The linear effects of main factors and interactions were evaluated. The calculated response surface model for the pressure/temperature was found to be significant for all the dependent variables. At optimal condition of SFE, the response variables were assessed as maximum extraction yield of 4.09 ± 0.69%, total betacyanins content of 25.49 ± 1.54 mg/100 mL, redness (a*) of 58.18 ± 0.82, and IC50 (antioxidant activity) of 1.34 ± 0.12 mg/mL for the experimental peel extracts. The optimal levels of independent variables were validated for the experimental responses as predicted by the mathematical model. The reliability of this method was confirmed as there was no significant difference between experimental and predicted values. The HPLC-MS profile of betacyanins extract comprised of both acylated and non-acylated betacyanins constituents.

Matched MeSH terms: Carbon Dioxide
Geochemical fractionation of hazardous elements in fresh and drilled weathered South African coal fly ashes

Akinyemi SA, Gitari WM, Thobakgale R, Petrik LF, Nyakuma BB, Hower JC, et al.

Environ Geochem Health, 2020 Sep;42(9):2771-2788.
PMID: 31900823 DOI: 10.1007/s10653-019-00511-3

The chemical reactions of dry-disposed ash dump, ingressed oxygen, carbon dioxide, and infiltrating rainwater affect mineralogical transformation, redistribution, and migration of chemical species. Composite samples of weathered coal fly ash taken at various depths and fresh coal fly ash were examined using organic petrographic, X-ray diffraction, X-ray fluorescence techniques, and successive extraction procedures. Results obtained show relative enrichment of glass, Al-Fe-oxides, calcite, and tridymite in the weathered CFA, but the fresh CFA is enriched in mullite, inertinite, maghemite, and ettringite. The enrichment of the weathered CFA in amorphous glass suggests higher reactivity when compared to fresh CFA. The evident depletion of soluble oxides in the weathered CFA is attributed to flushing of the soluble salts by percolating rainwater. Comparative enrichment of examined elements in water-soluble, exchangeable, reducible, and residual fractions of the weathered CFA is partly due to the slow release of adsorbed chemical species from the alumina-silicate matrix and diffusion from the deeper sections of the particles of coal fly ash. Sodium and potassium show enrichment in the oxidisable fraction of fresh CFA. The estimated mobility factor indicates mobility for Ca, Mg, Na, Se, Mo, and Sb and K, Sr, V, Cu, Cr, Se, and B in fresh and weathered CFAs, respectively.

Matched MeSH terms: Carbon Dioxide
Fulltext Bioremediation and Electricity Generation by Using Open and Closed Sediment Microbial Fuel Cells

Abbas SZ, Rafatullah M, Khan MA, Siddiqui MR

Front Microbiol, 2018;9:3348.
PMID: 30692985 DOI: 10.3389/fmicb.2018.03348

The industrial contamination of marine sediments with mercury, silver, and zinc in Penang, Malaysia was studied with bio-remediation coupled with power generation using membrane less open (aerated) and closed (non-aerated) sediment microbial fuel cells (SMFCs). The prototype for this SMFC is very similar to a natural aquatic environment because it is not stimulated externally and an oxygen sparger is inserted in the cathode chamber to create the aerobic environment in the open SMFC and no oxygen supplied in the closed SMFC. The open and closed SMFCs were showed the maximum voltage generation 300.5 mV (77.75 mW/m2) and 202.7 mV (45.04 (mW/m2), respectively. The cyclic voltammetry showed the oxidation peak in open SMFCs at +1.9 μA and reduction peak at -0.3 μA but in closed SMFCs oxidation and reduction peaks were noted at +1.5 μA and -1.0 μA, respectively. The overall impedance (anode, cathode and solution) of closed SMFCs was higher than open SMFCs. The charge transfer impedance showed that the rates of substrate oxidation and reduction were very low in the closed SMFCs than open SMFCs. The Nyquist arc indicated that O2 act as electron acceptor in the open SMFCs and CO2 in the closed SMFCs. The highest remediation efficiency of toxic metals [Hg (II) ions, Zn (II) ions, and Ag (I) ions] in the open SMFCs were 95.03%, 86.69%, and 83.65% in closed SMFCs were 69.53%, 66.57%, and 65.33%, respectively, observed during 60-80 days. The scanning electron microscope and 16S rRNA analysis showed diverse exoelectrogenic community in the open SMFCs and closed SMFCs. The results demonstrated that open SMFCs could be employed for the power generation and bioremediation of pollutants.

Matched MeSH terms: Carbon Dioxide
The heterogeneous effects of urbanisation and institutional quality on greenhouse gas emissions in Belt and Road Initiative countries

Lee HS, Arestis P, Chong SC, Yap S, Sia BK

Environ Sci Pollut Res Int, 2022 Jan;29(1):1087-1105.
PMID: 34341929 DOI: 10.1007/s11356-021-15699-0

The rise of urbanisation in Belt and Road Initiative (BRI) countries that contribute to the disruption of the ecosystem, which would affect global sustainability, is a pressing concern. This study provides new evidence of the impact of urbanisation and institutional quality on greenhouse gas (GHG) emissions in the selected 48 BRI countries from the years 1984 to 2017. The models of this study are inferred by using panel regression model and panel quantile regression model to meet the objectives of our study as it contemplates unobserved country heterogeneity. From the panel regression model, the findings indicate that although urbanisation in BRI supports the 'life effect' hypothesis that could dampen the environment quality, this effect could be reduced through better institutional quality. Using the quantile regression method, this study concludes that one-size-fits-all strategies to reduce GHG emissions in countries with different GHG emissions levels are improbable to achieve success for all. Hence, GHG emissions control procedures should be adjusted differently across high-emission, middle-emission and low-emission countries. Based on these results, this study provides novel intuitions for policymakers to wisely plan the urbanisation blueprints to eradicate unplanned urbanisation and improve institutional quality in meeting pollution mitigation goals.

Matched MeSH terms: Carbon Dioxide/analysis

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