•CO2-saturated brine significantly reduced hydrophilicity of sandstone•Sandstone is significantly less hydrophilic when exposed to CO2-water mixtures•Sandstone is originally strongly water-wet but ...turns weakly water-wet when CO2 is present at reservoir conditions
CO2-rock wettability is a key parameter which governs CO2 trapping capacities and containment security in the context of CO2 geo-sequestration schemes. However, significant uncertainties still exist in terms of predicting CO2 rock wettability at true reservoir conditions. This study thus reports on wettability measurements via independent Nuclear Magnetic Resonance (NMR) experiments on sandstone (CO2–brine systems) to quantify Wettability Indices (WI) using the United States Bureau of Mines (USBM) scale. The results show that CO2 (either molecularly dissolved or as a separate supercritical phase) significantly reduced the hydrophilicity of the sandstone from strongly water-wet (WI ≈ 1) to weakly water-wet (WI = 0.26), and associated with that the water-wetness of the rock for the two-phase systems. This was caused by additional protonation of surface silanol groups on the quartz, induced by carbonic acid. Capillary pressure and relative permeability curves and residual CO2 saturation were also measured; these results were compared with literature data, and general consistency was found. NMR T2 distribution measurements also demonstrated preferential water displacement in large pores (r > 1 µm) following scCO2 flooding, while no change was observed for smaller pores (r < 1 µm). These insights add confidence to the assessments of CO2-rock wettability and therefore reduce project risk. This work thus aids in the implementation of large-scale CO2 sequestration.
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•Production and optimisation of an economic medium to high strength Eco-efficient SCC.•RSM and multi-objectives optimisation used to maximise flow and compressive strength.•Models for ...both flow and compressive strength have been developed and verified.
This study aims to produce and optimize Eco-efficient self-compacting concrete (SCC) mixes using multi-waste substitutions. The main input parameters of mixes were total binder, fine aggregate and water contents whereas slump flow and compressive strength were the two main operational responses of produced concrete. Limestone powder (LP) and waste Polyethylene Terephthalate (PET) were used in concrete as parts of cement and fine aggregate respectively with high range water reducing admixture (SP) as part of water. Response Surface Methodology (RSM) and multi-objectives optimization using Minitab 17 statistical software were employed for this purpose.
Twenty SCC mixes were designed and checked experimentally using Central Composite Design (CCD) concept in RSM. Mathematical models were established and evaluated using analysis of variance test (ANOVA) according to the experimental results. This is in order to define the effectiveness degree of design parameters on the properties required and to adjust the derived mathematical models. Multi-objectives optimization process was adopted to determine the optimum values of the input parameters. The optimization revealed that the optimum values of the input factors, LP, PET and SP were 20.1%, 2.4% and 1.16% by weight respectively. These theoretical values were checked experimentally and the achieved responses were quiet similar or higher than the best proposed mix.
It was deduced that the developed models can be used to ensure a speedy mix design process by achieving maximum tested properties of eco-efficient SCC.
In order to meet climate goals, both CO2 capture and storage (CCS) and CO2 capture and utilization (CCU) have been identified as increasingly important technologies for mitigating CO2 emissions that ...are difficult to avoid. In this work, the CO2 utilization, or more specifically, the CO2 conversion to fuels and urea, considering the large demand for CO2, as well as the CO2 mineralization are surveyed and reviewed. The content of this review includes technologies – all the way from the laboratory studies to the industrial applications – their current status, and future potential. CCS is included for a comparison concerning the costs. Also, aspects as the CO2 impurities and the effect of it as well as various requirements concerning the CO2 impurity are included. Many recent studies show that CCU, especially CO2 conversion to fuels, will play an essential role in mitigating CO2 emissions, while developed methods and technologies are not yet mature. More research work needs to be conducted to improve the process efficiency via developing catalysts and reducing the cost of producing H2 that is used as a reactant for fuel synthesis. Moreover, current literature also shows that impurities will affect the process of both CCS and CCU, while the work of studying their influence, especially on CCU, is still scarce. The cost of CCS has been estimated combined with impurities, while studies on cost estimation for CCU are still limited, and the cost, in general, is relatively high with the currently available technologies.
•CCU plays an essential role in mitigating CO2 emissions, while development is immature.•The costs of CCS and CCU are relatively high compared to the present price of emitting CO2 emissions.•The impurities will affect the process of both CCS and CCU, but the work, especially on CCU, is still scarce.
Heavy metals, organic pollutants, carbon dioxide (CO2), pathogenic bacteria as the main contaminants of water, soil, and air are generated by the exponential increase in the world's population and ...industrial as well as civilization, agricultural and domestic activities. They are not only hazardous to human health but also noxious to the ecosystem, this led researchers to test and assess other effective, environmentally friendly and low-cost materials, in order to minimize these impacts. Presently, the layered silicates materials in which their structures are composed of only SiO4 tetrahedra provide many attractive physicochemical properties. Especially, magadiite which has received increasing attention in recent years, many of which environmental contaminants have been removed by adsorbents based on magadiite; that designates it to be promising material for composites and hybrids fabrication. This mineral has shown good conservation of its lamellar structure during hybridization as well as an improvement in the mechanical, chemical and thermal stability of composites containing magadiite. This review assesses the removal contaminants performance by layered silicates materials in general and the magadiite and its composites in particular. For this, the adsorption capacity of dyes, heavy metals, (CO2) and pesticides are discussed in detail, as well as the antimicrobial activity of these materials were evenly mentioned. The main properties of layered silicates in the elimination of contaminants are evaluated and the known weak points of their applying were evenly discussed in other conduce the suggestions for further research.
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•Literature investigation and opinions on the environmental applications of magadiite and its composites.•The characterization techniques used for magadiite identification has been summarized.•The adsorption capacity and selectivity of based magadiite adsorbents were compared.•Antimicrobial properties of magadiite and its composites are discussed.•Remarks on challenges and opportunities for layered silicate magadiite applications.
Carbon dioxide (CO2) is the main greenhouse gas responsible for global warming. Early prediction of CO2 is critical for developing strategies to mitigate the effects of climate change. A ...sophisticated version of the extreme learning machine (ELM), the wavelet enhanced extreme learning machine (W-EELM), is used to predict CO2 on different time scales (weekly, monthly, and yearly). Data were collected from the Mauna Loa Observatory station in Hawaii, which is ideal for global air sampling. Instead of the traditional method (singular value decomposition), a complete orthogonal decomposition (COD) was used to accurately calculate the weights of the ELM output layers. Another contribution of this study is the removal of noise from the input signal using the wavelet transform technique. The results of the W-EELM model are compared with the results of the classical ELM. Various statistical metrics are used to evaluate the models, and the comparative figures confirm the superiority of the applied models over the ELM model. The proposed W-EELM model proves to be a robust and applicable computer-based technology for modeling CO2concentrations, which contributes to the fundamental knowledge of the environmental engineering perspective. Doi: 10.28991/CEJ-2023-09-04-04 Full Text: PDF
The use of concentrated carotenoid extracts from red-ripe tomato by-products in traditional foods can improve the functional properties of the product while increasing the efficiency of industrial ...red-ripe tomatoes processing. In red tomatoes, lycopene is almost exclusively found in the all-trans-form, but during processing lycopene can undergo isomerisation to cis-lycopene isomers. The cis-lycopene isomers offer potentially better health benefits than the trans-lycopene isomers. The objectives of this study were to optimize supercritical carbon dioxide (SC-CO2) extraction parameters for the isolation of the non-polar tomato by-product fraction (oleoresin) and cis-lycopene isomers by using a central composite rotatable design (CCD) model with response surface methodology (RSM). SC-CO2 using CCD and RSM was used for the first time for the isolation of cis-lycopene isomers from tomato by-products. The best results in terms of oleoresin yield were obtained at a temperature of 73.9 °C, a pressure of 53.7 MPa and a time of 155 min, whereas the optimal extraction process parameters of cis-lycopene isomers are a 52 °C temperature, a 55 MPa pressure and a 180 min extraction time. The optimized conditions of SC-CO2 allows to obtain high yields of lycopene rich extracts (oleoresins) comprising higher percentage of cis-lycopene isomers (∼62% of total lycopene).
•Tomato by-products oleoresin was extracted using supercritical CO2.•Optimal conditions for cis-lycopene isomers extraction was determined.•Full factorial design was used to understand the effect of process variables.•The optimum conditions were 52 °C, 55 MPa and 180 min.
•An overview of Hybrid Power Generation Systems within Mini-grids is presented.•A novel survey of PV integration into existing fossil fuel-based Power Generation Systems is performed.•Great Algerian ...South mini-grids are introduced and the experience of PV integration into three of them is assessed.•Further approaches to increase the PV penetration level of the Hybrid Power Generation Systems are proposed.
Electricity is essential in modern life, yet almost one billion people in the world, living mainly in rural and remote areas, do not have access to it. Thus, local mini-grids deployment seems to be an attractive solution for scaling up access to electricity in these areas far from the main grid. The currently implemented mini-grids worldwide rely almost entirely on fossil fuel-based Power Generation Systems (PGSs). However, the high operational expenditure and the harmful impact on the environment associated with the use of these sources are increasingly inciting countries to promote the Renewable Energy Sources (RESs) integration into those power generation systems for a more sustainable and more extended electricity supply.
In this context, the paper aims to present a comprehensive overview of the Hybrid Power Generation System (HPGS) concept application for mini-grids as well as a novel survey that analyses feedbacks from centralized PV system integration into existing fossil fuel-based PGSs achieved projects worldwide. Then, recent key figures of the Great Algerian South mini-grids and the experience of storage-less PV capacities integration into the fossil fuel-based PGSs feeding three of them are for the first time introduced. The analysis of the 2019-year operation data of the HPGSs thus formed reveals the positive outcomes retrieved from this first experience in terms of fuel saving and CO2 emissions reduction despite the proven low PV penetration level. Given the high solar PV energy potential characterizing the Great Algerian South localities, the performed overview and experiences assessment may provide an incentive for decision makers to pursue undertaking such hybridization projects and to prospect additional options that may increase the achievable PV penetration levels and thus further reduce the dependency of those localities on costly and polluting fossil fuel sources. Hence, the findings of this study will hopefully be beneficial to other mini-grid cases for either new construction or retrofitting projects.
This paper examines the relationship between the logarithms of carbon dioxide (CO2) emissions and real Gross Domestic Product (GDP) in China by applying fractional integration and cointegration ...methods. These are more general than the standard methods based on the dichotomy between stationary and non-stationary series, allow for a much wider variety of dynamic processes, and provide information about the persistence and long-memory properties of the series and thus on whether or not the effects of shocks are long-lived. The univariate results indicate that the two series are highly persistent, their orders of integration being around 2, whilst the cointegration tests (using both standard and fractional techniques) imply that there exists a long-run equilibrium relationship between the two variables in first differences, i.e. their growth rates are linked together in the long run. This suggests the need for environmental policies aimed at reducing emissions during periods of economic growth.
One of the most significant thermodynamic cycles in the refrigeration and air conditioning industry is the trans-critical carbon dioxide cycle. The fundamental trans-critical carbon dioxide ...refrigeration cycle performs poorly, which inspired researchers to develop innovative technologies to increase its energy efficiency. One of the most appealing ways to improve cycle performance is to employ a porous internal heat exchanger. For this, a porous internal heat exchanger, compressor, gas cooler, expansion valve, evaporator and experimental test rig are constructed. For the internal heat exchanger’s porous material, sea sand with porosities of 35%, 42% and 51% is used. It is also taken into account when the internal heat exchanger’s tube is empty (porosity = 100%). Investigations were conducted on the cycle refrigeration capacity, coefficient of performance, pressure drop, internal heat exchanger effectiveness, relative refrigeration capacity index and compressor power consumption per kW of refrigeration in relation to changes in the gas cooler discharge temperature, gas cooler working pressure, evaporation temperature, internal heat exchanger porosity and degree of subcooling. When the gas cooler discharge temperature was lowered from 53 to 34 °C and the porosity was reduced from 100 to 35%, the cycle refrigeration capacity and coefficient of performance were raised by 49.7% and 93%, respectively. An increase in refrigeration capacity of 46% and increase in coefficient of performance of 87.5% were the consequence of raising the degree of subcooling from 2 to 12 °C and lowering porosity from 100 to 35%. By reducing the internal heat exchanger’s porosity from 100 to 35%, the compressor’s power consumption per kW of refrigeration is reduced by around 29.6%.
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