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1.
Heliyon ; 10(7): e27682, 2024 Apr 15.
Article in English | MEDLINE | ID: mdl-38601637

ABSTRACT

The emergence of new suppliers and energy resources has reshaped the energy market in terms of contractual structures and pricing systems. The market shifts were accelerated in response to the latest Russian-Ukraine crisis, impacting natural gas supply chains from financing projects to contracting volumes. The increased demand for liquified natural gas volumes intensified the need to switch from long-term oil-indexed contracts to short-term gas-indexed contracts. Those shifts were anticipated to influence the selling strategies for the expected added 49 MTPA of Qatari LNG, wherein increasing the share of spot selling would be reflected in higher economic performance. This study used forecasted prices to investigate potential Qatari LNG selling strategies. Initially, projections of the most dominant pricing systems used for pricing Qatari LNG (i.e., brent, Henry Hub, Title Transfer Facility, and Japan Korea Marker) were estimated between 2023 and 2040. While Qatar has been relying on long-term oil-indexed contracts, the second step estimated annual LNG revenues under different combinations of selling strategies (i.e., long-term and spot sales). Finally, the influence of varying brent slopes on the estimated revenues was measured. Due to data limitations and non-stationarity, the double exponential smoothing model was selected among the different tested models. Considering current market dynamics, forecasts of the double exponential smoothing model showed an upward price trend until 2040. An annual average increase of 1.24% for the studied pricing systems was reported. Reducing the share of long-term brent-indexed contracts to 70% and dedicating the remaining 30% of volumes to spot sales yielded the highest premiums for revenue estimates. An average annual revenue of $62 bn was reported for the 70/30 strategy, around 6% higher than the 100% brent-indexed contracts strategy. The findings revealed that diversifying the selling approach and introducing spot sales can enhance revenues. From the buyers' perspective, the outcomes support policymakers in understanding the implications of escalated prices driven by a lack of liquidity investments.

2.
Heliyon ; 10(6): e27713, 2024 Mar 30.
Article in English | MEDLINE | ID: mdl-38524540

ABSTRACT

Food waste has become a source of concern as it is generated abundantly worldwide and needs to be valorised into new products. In this study, cucumber, tomato, and carrot wastes were investigated as pyrolysis feedstocks as a single component (cucumber), a binary component mixture (cucumber and tomato), and a ternary component blend (cucumber, tomato, and carrot). Fourteen scenarios were simulated and evaluated based on varying the feedstock blend (single, binary, and tertiary), temperature (300 and 500 °C), and feedstock moisture content (5, 20, and 40%). Using an established empirical model, the effect of these parameters on product yields, techno-economic implications, energy requirements, and life cycle analysis (LCA) outcomes were investigated. The best performers of each scenario were determined, and their strengths and weaknesses were identified and compared with other scenarios. In terms of product yields, all three systems (single, binary, and tertiary) followed a similar pattern: bio-oil yields increased as temperature and feedstock moisture content increased, while biochar yields decreased as temperature and feedstock moisture content increased. The production of syngas, on the other hand, was only observed at elevated temperatures. The total energy requirement exhibited an increase with increasing temperature and feedstock moisture content. The economic evaluation revealed that the return on investment (ROI) value for the single component at 5% moisture content at 300 °C is 29%, with a payback period (PB) of only 3.4 years, which is potentially very appealing. The water footprint increased with increasing pyrolysis temperature but decreased with increasing moisture content in all scenarios. The land footprint is observed to remain constant despite changes in process conditions. The study's findings contribute to the pyrolysis process's scalability, technological advancement, and commercialisation.

3.
PLoS One ; 19(3): e0299350, 2024.
Article in English | MEDLINE | ID: mdl-38427638

ABSTRACT

Agricultural Remote Sensing has the potential to enhance agricultural monitoring in smallholder economies to mitigate losses. However, its widespread adoption faces challenges, such as diminishing farm sizes, lack of reliable data-sets and high cost related to commercial satellite imagery. This research focuses on opportunities, practices and novel approaches for effective utilization of remote sensing in agriculture applications for smallholder economies. The work entails insights from experiments using datasets representative of major crops during different growing seasons. We propose an optimized solution for addressing challenges associated with remote sensing-based crop mapping in smallholder agriculture farms. Open source tools and data are used for inter and intra-sensor image registration, with a root mean square error of 0.3 or less. We also propose and emphasize on the use of delineated vegetation parcels through Segment Anything Model for Geospatial (SAM-GEOs). Furthermore a Bidirectional-Long Short-Term Memory-based (Bi-LSTM) deep learning model is developed and trained for crop classification, achieving results with accuracy of more than 94% and 96% for validation sets of two data sets collected in the field, during 2 growing seasons.


Subject(s)
Agriculture , Satellite Imagery , Agriculture/methods , Farms , Seasons , Crops, Agricultural
4.
Foods ; 12(21)2023 Oct 25.
Article in English | MEDLINE | ID: mdl-37959033

ABSTRACT

Maritime transportation plays a critical role for many Arab countries and their food security and has evolved into a complex system that involves a plethora of supply chain stakeholders spread around the globe. This inherent complexity brings huge security challenges, including cargo loss and high burdens in cargo document inspection. The emerging blockchain technology provides a promising tool to build a unified maritime cargo tracking system critical for cargo security. This is because blockchains are a tamper-proof distributed ledger technology that can store and track data in a secure and transparent manner. Using the State of Qatar as a case study, this research introduces the Global Maritime Ledger (GM-Ledger), which will aid authorities in verifying, signing and transacting food certificates in an efficient manner. The methodology of this research includes reviewing past publications, identifying the requirements of various players in the Qatari food import-export industry and then creating a smart contract framework that will efficiently manage the work with necessary human intervention as and when required. The result of this work is the formation of a solid framework that can be employed in future works. This work realized that employing web3 solutions for the food import sector is highly viable and that with the right social, economic and policy reforms, it is possible to transform the entire food system to bear healthy transparency and power balance in global supply chains. In conclusion, this study argues that BCT has the ability to assist the government and other players to minimize fraud and maximize food supply chain stakeholder participation.

5.
Heliyon ; 9(7): e17773, 2023 Jul.
Article in English | MEDLINE | ID: mdl-37496899

ABSTRACT

The food needs of the increasing global population, inefficiencies in supply chains, customer expectations and environmental concerns are the challenges to meeting resource-intensive protein needs sustainably. Collectively, this increases the need to enhance sustainability in the beef sector. This study proposes a sliding time-window-based multi-period livestock production model using mixed-integer linear programming (MILP) to simultaneously balance economic and environmental losses. It identifies the optimal finishing time using frame score (FS) and feed conversion ratio (FCR), targeting flexibility by allowing variable growth periods to reduce food/nutritional losses while meeting the variability in demands with minimum inventory levels. Furthermore, sequencing and assigning animals to facilities with optimum separation time is applied to avoid bad handling of animals and ensure quality meat with hygienic standards for longer shelf life. The system boundary of the proposed model includes beef farms and processing facilities. Compared to the recently proposed batch processing models over seven months with a herd size of 1980 animals, the findings reduce the average forage needed by ∼126.90 kips and methane emissions by ∼2560 kg, with a significant benefit in terms of the live animals' weight gain by ∼10,276 lbs.

6.
Glob Chall ; 7(6): 2200229, 2023 Jun.
Article in English | MEDLINE | ID: mdl-37287589

ABSTRACT

The objective of this paper is to present a comprehensive perspective on the development of a long-term low-emission development strategy for Qatar, in line with the Paris Agreement. The methodology used in this paper takes a holistic approach by analyzing national strategies, structures, and mitigation measures from other countries, and synthesizing these with Qatar's unique context in terms of its economy, energy production, and consumption, as well as its energy-related emission profile and characteristics. The findings of this paper identify key considerations and elements that policymakers would need to take into account when developing a long-term low-emission vision for Qatar, with a particular emphasis on its energy sector. The policy implications of this study are significant for policymakers in Qatar, as well as for other countries facing similar challenges in their transition to a sustainable future. This paper contributes to the discourse on energy transition in Qatar and provides insights that can inform the development of potential routes to reduce greenhouse gas emissions in Qatar's energy system. It serves as a foundation for further research and analysis and can contribute to the development of more effective and sustainable policies and strategies for low-emission development in Qatar and beyond.

7.
Heliyon ; 9(6): e16358, 2023 Jun.
Article in English | MEDLINE | ID: mdl-37265620

ABSTRACT

The expectation in global demand for liquified natural gas (LNG) remains bullish in the coming years. Despite the unprecedented impact of the COVID-19 pandemic, and the oil price wars between OPEC and Russia in 2020, causing oversupply and falling prices, the LNG markets continue to demonstrate flexibility and resilience in delivering the needs of different sectors, whilst helping achieve the emissions targets. This is attributed to the high competitiveness amongst LNG producers and suppliers, providing greater confidence for medium-to-long term demand. However, the uncertainties in the current outlook for the return of demand and price growth in the post-COVID period pose difficulty for new liquefaction project investment decisions in the pre-Investment Decision Phase (pre-FID). Accordingly, the consideration of new production and selling strategies is needed in the early design stages of projects to cope with the shift in buyers' sentiments favouring increased reliance on spot and short-term uncontracted volumes, as well as incorporating additional flexibility into long-term contracts. In this study, the economic valuation of the flexible Air Product's AP-X liquefaction technology was investigated considering the modelling of price volatilities, using the mean-reverting jump-diffusion pricing model and Monte Carlo simulation, assuming different demand level scenarios in the high-income Asia Pacific markets based on historical trends. The results clearly demonstrate that embedding flexibility within an LNG production system allows producers and suppliers to diversify selling strategies, and take advantage of the lucrative market conditions when demand and prices increase, and hedge against market risks when demand and prices are low.

8.
Heliyon ; 9(4): e15344, 2023 Apr.
Article in English | MEDLINE | ID: mdl-37151622

ABSTRACT

For decades, the notion of 'Free Zones' has remained complex and ambiguous. Despite considerable efforts in this regard, the concept of 'Free Zones' and its components have not been sufficiently explored. To further consolidate the related literature, this study conducted a literature review on the terminology of the Free Zone and its components using a systematic review method based on literature and international organizations such as the UNCTAD. This study provides needed general knowledge about the nature of Free Zones. It also presents the classifications and types of economic zones, and provides insight into what distinguishes Free Zones and economic zones from one another. Furthermore, it aggregates the Free Zone into its constituting components, concluding with insight into future research by identifying relevant challenges and gaps.

9.
RSC Adv ; 13(9): 5687-5722, 2023 Feb 14.
Article in English | MEDLINE | ID: mdl-36816069

ABSTRACT

The increasing concentration of carbon dioxide (CO2) in the atmosphere has compelled researchers and policymakers to seek urgent solutions to address the current global climate change challenges. In order to keep the global mean temperature at approximately 1.5 °C above the preindustrial era, the world needs increased deployment of negative emission technologies. Among all the negative emissions technologies reported, direct air capture (DAC) is positioned to deliver the needed CO2 removal in the atmosphere. DAC technology is independent of the emissions origin, and the capture machine can be located close to the storage or utilization sites or in a location where renewable energy is abundant or where the price of energy is low-cost. Notwithstanding these inherent qualities, DAC technology still has a few drawbacks that need to be addressed before the technology can be widely deployed. As a result, this review focuses on emerging trends in direct air capture (DAC) of CO2, the main drivers of DAC systems, and the required development for commercialization. The main findings point to undeniable facts that DAC's overall system energy requirement is high, and it is the main bottleneck in DAC commercialization.

10.
Foods ; 12(2)2023 Jan 04.
Article in English | MEDLINE | ID: mdl-36673322

ABSTRACT

Finding a balance between the capacity for production and the rising demand for food is the first step toward achieving food security. To achieve sustainable development on a national scale, decision-makers must use an energy, water, and food nexus approach that considers the relationships and interactions among these three resources as well as the synergies and trade-offs that result from the way they are handled. Therefore, this paper evaluates the Energy-Water-Food Nexus Profile of Qatar at a superstructural level by applying the Business-As-Usual (BAU) storyline; thus, trends of past data have been used to provide future projections to 2050 using the statistical prediction tools such as the compound annual growth rates of food demand (CAGRFD), international supply (CAGRFI), and the average local food supply change factor (c¯). Once the BAU storyline has been generated, the source-to-demand correlations have been defined for each food category. Such correlations include the annual and average ratios of the local food supply to the total demand (i.e., αi and α¯) and the ratios of the local food supply to the international supply (i.e., ßi and ߯). In addition, as an effort to identify the required action to reach food self-sustainability, the additional local food supply to achieve (xi,add) and its ratio to the local demand (γ) have been defined. The highest average ratio of the local food supply to the total demand (αi) was found for the meat category, which was estimated to be 48.3%. Finally, to evaluate the feasibility of attaining food self-sustainability in Qatar, the water consumption (Vw,i) and its corresponding required energy for each food category have been estimated.

11.
Chemosphere ; 313: 137425, 2023 Feb.
Article in English | MEDLINE | ID: mdl-36460158

ABSTRACT

Polyethersulfone (PES) is a widely used polymer for ultrafiltration (UF) membrane fabrication. In the current study, carbide-derived carbon (CDC) oxidized by acid treatment was utilized as a filler to fabricate a novel PES composites UF membranes. The successful oxidation of CDC was validated from presence of oxygen containing functional groups and improved oxygen content, from 5.08 at.% for CDC to 26.22 at.% for oxidized CDC (OCDC). The OCDC PES UF membranes were prepared at different loadings of OCDC between 0.5 and 3.0 wt%. The membrane porosity, pore size and surface free energy found to be improved while a noticeable reduction in water contact angle was observed with OCDC loading implying the improved hydrophilicity of PES membranes. Consequently, the pure water flux found to improve from 151.6 to 569.6 (L/(m2. h)) for the 3.0 wt% modified OCDC membrane (M-3) which is 3.8 folds of the bare PES membrane. The antifouling characteristics were evaluated by humic acid (HA) filtration. The results revealed a significant enhancement in HA rejection with OCDC loading, the highest rejection was 96.8% for M-3 membrane. Additionally, the adsorption capacity of OCDC modified membranes found to decrease with OCDC loading indicating improved rejection of HA from the membrane surface. Moreover, M-3 demonstrated the maximum flux recovery ratio (FRR) of 92.3%. Reusability of the fabricated membranes was evaluated by deionized water/humic acid cycling filtration. The FRR was higher than 86.7% over three cycles of pure water/HA filtration for 140 min, indicated the excellent stability and reusability of the membranes. Overall, the OCDC was an effective filler for enhancing the PES UF membranes antifouling and permeability properties.


Subject(s)
Biofouling , Ultrafiltration , Ultrafiltration/methods , Carbon , Humic Substances/analysis , Biofouling/prevention & control , Membranes, Artificial , Polymers , Water
12.
J Environ Manage ; 323: 116223, 2022 Dec 01.
Article in English | MEDLINE | ID: mdl-36261981

ABSTRACT

Jatropha curcas L. (JCL) is one of the most prominent energy crops due to its superior agronomical traits, where it can grow in non-arable lands and harsh climates with minimal water requirements. A significant number of studies were published on the utilisation of JCL for biofuel production, whereas there are no studies on its use in greenbelt (GB) or windbreak technologies reported thus far. Meanwhile, a few approaches on the delineation of greenbelts to fight desertification in the arid regions exist in literature. This study presents a novel approach to delineate a multipurpose energy-greenbelt using JCL crop for biofuel production, as well as to preserve the soil and enhance air quality, thereby helping to combat desertification and sand-dust storms (SDS). The methodology is demonstrated using a case study in the state of Qatar for the diversification of its renewable energy resources. Moreover, Qatar is also suffering from land degradation due to erosion factors and desert creep. A multi-dimensional approach is proposed for this purpose using satellite and meteorological data to initially select the optimal plantation sites that potentially contribute to the highest possible biofuel yield. The spatial analysis was carried out using the analytical hierarchy process (AHP) technique for multi-criteria decision making in the geographic information system (ArcGIS). In addition, the Landsat and MODIS satellite imagery were utilised in combination with historical records from the weather stations to evaluate the patterns of SDS, land degradation and urban expansion, to best define optimal GB pathway. COMSOL Multiphysics software was subsequently employed to evaluate the performance of Jatropha-GB and determine its optimal density. The different solutions for GB delineation spans 166.6-227.8 km length and (6 × 6 m) of field density. It is expected that the economic and environmental benefits from the derived GB configuration include: (a) protection of up to 87% of Qatar farms against further deterioration; (b) yield of up to 36 M gallon of green liquid fuels; (c) capture of 0.33 M tonnes of CO2 per 1 km GB-depth annually; and (d) provide a better air quality for around 95% of the Qatar population.


Subject(s)
Biofuels , Jatropha , Conservation of Natural Resources , Sand , Carbon Dioxide , Desert Climate , Soil , Dust , Water
13.
Heliyon ; 8(8): e10274, 2022 Aug.
Article in English | MEDLINE | ID: mdl-36061036

ABSTRACT

In 2018, the global annual consumption of Polyethylene terephthalate (PET) bottles was approximately 27.64 million tons, with one million bottles sold worldwide every minute. Unmanaged PET bottles in the environment lead to a series of negative effects on the health of humans and ecosystems. Therefore, the objective of this research was to evaluate the sustainability of eight different PET waste bottle treatment methods using a holistic multi-criteria decision-making approach that combined the technique for order of preference by similarity to ideal solution (TOPSIS) with analytic hierarchy (AHP; TOPSIS-AHP) and coefficient of variation (COV; TOPSIS-COV) approaches. To the best of our knowledge, TOPSIS-COV has not yet been used for waste management. The treatment methods were compared and analyzed against twelve different performance criteria representing three pillars of sustainability: environmental, economic, and social. Both approaches determined closed-loop recycling to be optimal for treating PET waste bottles. The weights of performance indicators obtained using the COV and AHP approaches were comparable, except for cost, photochemical oxidant potential, and human toxicity. The large dispersion in the values of the photochemical oxidant potential causes it to have a higher weight in the COV approach. For cost, the weight was higher using the AHP approach by approximately 12%, which reflects the preference of decision-makers to reduce costs of ventures.

14.
Sensors (Basel) ; 22(17)2022 Aug 24.
Article in English | MEDLINE | ID: mdl-36080806

ABSTRACT

Tumor-derived exosomes may provide biomarkers for cancer treatment. Using sputtering technology, an affinity-based device to capture exosomes was developed using nanoporous substrate (NPG)-coated silicon microscopy. Immunology-based techniques detect and purify exosomes using gold coating with a specific antigen. Inverted fluorescent microscopy was used to detect target exosomes quantitatively utilizing fluorescent nanospheres as the label. We quantified the expression of CD63 surface protein markers on exosomes from conditioned culture media of breast cancer cells. The exosomes that targeted specific proteins with controls were statistically analyzed and compared to those that targeted non-specific proteins. Results from SEM showed that the exosomes were circular, between 30 and 150 nanometers in size. The porous gold substrates captured more exosomes than the nonporous substrates. Nitric acid treatments at different times resulted in a variety of pore sizes. Despite the increase in the size of the pores, the number of exosomes found in the porous gold substrate treated for 10 min nearly doubled compared to the one treated for 5 min. In this work, a fluorescence biosensor was developed to detect breast cancer exosomes using nanoporous gold substrates (NPG). Assay and model exosomes of specific breast cancer cells showed that exosomes exhibit diagnostic surface protein markers, reflecting the protein profile of their parent cells. Furthermore, the specific binding between the exosome surface antibodies and the targets identified the CD63 biomarkers on the exosome, suggesting these markers' diagnostic potential. This study can accelerate exosome research in determining tumor-related exosomes and develop novel cancer diagnostic methods.


Subject(s)
Breast Neoplasms , Exosomes , Nanopores , Biomarkers/metabolism , Biomarkers, Tumor , Breast Neoplasms/diagnosis , Breast Neoplasms/metabolism , Cell Line, Tumor , Exosomes/metabolism , Female , Gold , Humans , Membrane Proteins/metabolism , Spectrophotometry
15.
Chemosphere ; 307(Pt 3): 135953, 2022 Nov.
Article in English | MEDLINE | ID: mdl-35964727

ABSTRACT

In the present work, the adsorptive removal of chromium (Cr) from water by carbide-derived carbon (CDC) was investigated. The morphology and structure of the CDC were characterized by using FTIR, SEM, TEM, XRD, and N2 adsorption-desorption measurements. The effect of adsorption parameters including contact time, initial Cr concentration, temperature, initial solution pH, and CDC dosage was examined on the removal of Cr ions. The kinetic analysis revealed that the experimental data on the removal of Cr ions on CDC is well correlated with the pseudo-second order kinetic model (with R2 > 0.999), while the equilibrium data were fitted by the Redlich-Peterson isotherm model (with R2 > 0.992). The Langmuir and Sips models were also in good compliance with the equilibrium data, indicating a monolayer coverage of Cr ions onto the CDC surface with some heterogeneous active adsorption sites. The CDC revealed a notable Langmuir adsorption capacity of 159.1 mg/g for Cr ions at pH 6 and room temperature. The thermodynamic analysis illustrated that the Cr ions elimination by CDC is a feasible adsorption process and endothermic in nature. After five adsorption/desorption cycles, less than 18% reduction in the adsorption capacity was obtained indicating the stability and reusability of the CDC. Moreover, the CDC demonstrated an excellent potential in removing the Cr ions from real brackish water. According to the adsorption data, both physical and chemical adsorption processes occurred, and the adsorption was mainly controlled by electrostatic interactions with a possible reduction of hexavalent Cr to trivalent Cr at acidic conditions.


Subject(s)
Water Pollutants, Chemical , Water Purification , Adsorption , Carbon/chemistry , Chromium/analysis , Hydrogen-Ion Concentration , Ions , Kinetics , Organic Chemicals , Water , Water Pollutants, Chemical/analysis
16.
Biomass Convers Biorefin ; : 1-30, 2022 Jul 12.
Article in English | MEDLINE | ID: mdl-35855911

ABSTRACT

With ever-growing population comes an increase in waste and wastewater generated. There is ongoing research to not only reduce the waste but also to increase its value commercially. One method is pyrolysis, a process that converts wastes, at temperatures usually above 300 °C in a pyrolysis unit, to carbon-rich biochars among with other useful products. These chars are known to be beneficial as they can be used for water treatment applications; certain studies also reveal improvements in the biochar quality especially on the surface area and pore volume by imparting thermal and chemical activation methods, which eventually improves the uptake of pollutants during the removal of inorganic and organic contaminants in water. Research based on single waste valorisation into biochar applications for water treatment has been extended and applied to the pyrolysis of two or more feedstocks, termed co-pyrolysis, and its implementation for water treatment. The co-pyrolysis research mainly covers activation, applications, predictive calculations, and modelling studies, including isotherm, kinetic, and thermodynamic adsorption analyses. This paper focuses on the copyrolysis biochar production studies for activated adsorbents, adsorption mechanisms, pollutant removal capacities, regeneration, and real water treatment studies to understand the implementation of these co-pyrolyzed chars in water treatment applications. Finally, some prospects to identify the future progress and opportunities in this area of research are also described. This review provides a way to manage solid waste in a sustainable manner, while developing materials that can be utilized for water treatment, providing a double target approach to pollution management.

17.
Methods Protoc ; 4(4)2021 Nov 22.
Article in English | MEDLINE | ID: mdl-34842786

ABSTRACT

Drug counterfeits have been an international issue for almost two decades, and the latest statistics show that fake medications will continue to penetrate legitimate pharmaceutical supply chains (PSCs). Therefore, identifying the issues faced by PSCs is essential to combat the counterfeit drug problem, which will require the implementation of technologies in various phases of the PSC to gain better visibility. In this regard, a literature review was conducted to fulfill the following objectives: (i) review the application of traceability technologies in various PSC phases to detect counterfeits; (ii) analyze the various barriers affecting the establishment of a safe PSC and the critical success factors used to overcome those barriers; and (iii) develop a conceptual framework and guidelines to demonstrate the influence of traceability technologies and success factors on overcoming the various barriers in different phases of the PSC. The major finding of this review was that traceability technologies and the critical success factors have a significant influence on overcoming the barriers to establishing a safe PSC.

18.
Article in English | MEDLINE | ID: mdl-34618658

ABSTRACT

The objective of the study is to investigate the potential of carbide-derived carbon (CDC) for the adsorptive removal of nonionic t-octylphenoxy poly ethoxy ethanol (TX-100), anionic sodium dodecylbenzene sulfonate (SDBS) and cationic 1-hexadecylpyridinium bromide (HDPB) surfactants from water. The CDC was characterized using TEM, SEM, FTIR, BET, EDS, XPS methods and zeta potential measurements. The effects of adsorption parameters included initial surfactant concentration, contact time, temperature, and pH of the feed solution were evaluated. The adsorption capacity and mechanism were determined by modeling the isotherm, kinetic and thermodynamic data. The kinetics results demonstrated that the adsorption of the surfactant by CDC obeys the pseudo 2nd order model. The thermodynamic results have shown that surfactants adsorption by CDC is an endothermic and spontaneous process. The Sips model agreed with the adsorption isotherm data of SDBS with R2 of 0.987, while both Freundlich and Redlich-Peterson models comply well with adsorption data for TX-100 and HDPB. The hydrophobic and electrostatic interactions were found the dominant mechanisms of the adsorption of the surfactant by CDC. The adsorption capacities of CDC were found to be 442.4, 462.0 and 578.4 mg/g for SDBS, HDPB and TX-100, respectively.


Subject(s)
Surface-Active Agents , Water Pollutants, Chemical , Adsorption , Carbon , Hydrogen-Ion Concentration , Kinetics , Thermodynamics , Water , Water Pollutants, Chemical/analysis
19.
Sci Rep ; 11(1): 19227, 2021 Sep 28.
Article in English | MEDLINE | ID: mdl-34584160

ABSTRACT

This study presents a novel parametric investigation into the performance of a district cooling system using mono (Al2O3 and TiO2) and hybrid (Al2O3-TiO2) nanoparticles in the base fluids of water and ethylene-glycol water (EG-water) at a 20:80 ratio. The study analyses the effect of variables such as secondary fluid flow rate, evaporator and inlet temperatures, nanoparticle concentration, and air flowrate on the COP, total electrical energy consumption, and design of the district cooling unit. The analysis is performed with a thermal model developed and validated using operations data obtained from the McQuay chilled water HVAC unit operating in one of the facility plants at the Education City campus. The results of the study show that the use of nanofluids increased the overall heat transfer coefficient in the system by 6.6% when using Al2O3-TiO2/water nanofluids. The use of nanofluids in the evaporator also led to an average reduction of 23.3% in the total work input to the system and improved the COP of the system by 21.8%, 20.8% and 21.6% for Al2O3-TiO2/water, Al2O3/water, and TiO2/water nanofluids, respectively. Finally, an enhancement of 21.6% in COP was recorded for Al2O3-TiO2/EG-water nanofluids at a 5% nanoparticle volume concentration.

20.
J Environ Manage ; 287: 112345, 2021 Jun 01.
Article in English | MEDLINE | ID: mdl-33735671

ABSTRACT

In this work, the sustainable valorisation of camel manure has been studied using thermogravimetric analysis. The gasification tests were performed from ambient conditions to 950 °C at 10, 20, and 50 °C/min under an O2 environment. The TGA data were applied to determine the kinetics of the O2 gasification. Single-heating rate models (Arrhenius and Coats-Redfern) and multi-heating rate models (Distributed activation energy, Friedman, Flynn-Wall-Ozawa, Starink, and Kissinger-Akahira-Sunose) were applied to estimate the kinetics of the process. Between the two single-heating rate models, the Coats-Redfern method fitted best with the experimental data. Among the multi-heating rate models, the Flynn-Wall-Ozawa model fitted best with the experimental results. The kinetic parameters-frequency factor, activation energy, and order of reaction were estimated using the Flynn-Wall-Ozawa model (the best-fitting model) and the estimated kinetic parameters were used to calculate the thermodynamic properties-Gibbs free energy, enthalpy, and entropy. The information on these kinetic and thermodynamic properties can be useful for the design of gasifiers and for optimising the O2 gasification operating conditions.


Subject(s)
Camelus , Manure , Animals , Heating , Kinetics , Thermogravimetry
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