Water pollution caused by organic wastewater has become a serious concern worldwide. Fenton oxidation process is one of the most effective and suitable methods for the abatement of organic ...pollutants. However, the process has three obvious shortcomings: the narrow working pH range, the high costs and risks associated with handling, transportation and storage of reagents (H2O2 and catalyst), the significant iron sludge related second pollution. In order to overcome these shortcomings, various optimized Fenton processes have been widely studied. Therefore, a summary of the study status of Fenton optimization processes is necessary to develop a novel and high efficiency organic wastewater treatment method. Based on the optimization perspective, taking shortcomings of Fenton process as a breakthrough, the fundamentals, advantages and disadvantages of single Fenton optimization processes (heterogeneous Fenton, photo-Fenton and electro-Fenton) for organic wastewater treatment were reviewed and the corresponding reaction mechanism diagrams were drawn in this paper. Then, the feasibility and application of the coupled Fenton optimization processes (photoelectro-Fenton, heterogeneous electro-Fenton, heterogeneous photoelectro-Fenton, three-dimensional electro-Fenton) for organic wastewater treatment were discussed in depth. Additionally, the effect of some important operation parameters (pH and catalyst, H2O2, organic pollutants concentration) on the degradation efficiency of organic pollutants was studied to provide guidance for the optimization of operation parameters. Finally, the possible future research directions for optimized Fenton processes were given. The review aims to assist researchers and engineers to gain fundamental understandings and critical view of Fenton process and its optimization processes, and hopefully with the knowledge it could bring new opportunities for the optimization and future development of Fenton process.
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•Review of single Fenton optimization processes for organic wastewater treatment.•Review of coupled Fenton optimization processes for organic wastewater treatment.•Key operational parameters are discussed.•Insights into future research directions for optimized Fenton processes.
•Composition and properties of biomass were summarised.•Comparative characterization between biomass and coal was given.•Advantages of biomass composition and properties were described.•Disadvantages ...of biomass composition and properties were discussed.
An extended overview of the advantages and disadvantages of biomass composition and properties for biofuel application was conducted based on reference peer-reviewed data plus own investigations. Initially, some general considerations and comparisons about composition and properties of biomass and coal as the most popular solid fuel are addressed. Then, some of the major advantages related to the composition and properties of biomass and/or biomass ash (BA) are discussed. They include: (1) high values of volatile matter, H, structural organic components, extractives and reactivity of biomass, water-soluble nutrient elements and alkaline-earth elements in biomass and BA, and pH of BA; and (2) low values of C, fixed C, ash, N, S, Si and initial ignition and combustion temperatures of biomass, and low contents of many trace elements including hazardous ones in biomass and BA. Further, some of the major disadvantages connected with the composition and properties of biomass and/or BA are described. They comprise: (1) high values of moisture and O in biomass, water-soluble fraction, alkaline and halogen elements, and some hazardous trace elements in biomass and BA; (2) low values of energy density (bulk density and calorific value), pH and ash-fusion temperatures of biomass, and bulk density and size of BA; (3) highly variable composition and properties of biomass and BA; and (4) indefinite availability of sustainable biomass resources for production of biofuels. Finally, a discussion about the availability of sustainable biomass resources for production of biofuels and biochemicals is given. It was found that the disadvantages of biomass for biofuel and biochemical applications prevail over the advantages; however, the major environmental, economic and social benefits appear to compensate the technological and other barriers caused by the unfavourable composition and properties of biomass.
This survey presents a thorough overview of the main types of biomaterials used for the manufacturing of implants. The use of different materials for the creation and refinement of medical devices ...aims at optimizing their properties and raising the level of safety for the patients. The purpose of the study is to classify the most common bulk materials used in medicine according to their nature, interaction with the host tissues and their function in the organisms. Some important advantages and disadvantages of the different classes of implant materials are considered. In the last few years there is a strong tendency toward the surface modification of biomedical devices. Various trends in processing of the materials are focused on increasing their corrosion resistance, wear resistance, biocompatibility and microbiological properties.
•Five mixture design methods for SCC based on different principles are reviewed.•Feature and flow chart of mixture design procedure for each method is presented.•Advantages and disadvantages of each ...method is compared.•It provides valuable suggestions for choosing appropriate design method for SCC.
Mixture design is a very important step in production and application of concrete. Many mixture design methods have been proposed for self-compacting concrete (SCC). This paper presents a critical review on SCC mixture design methods in publications. Based on principles, those methods can be classified into five categories including empirical design method, compressive strength method, close aggregate packing method and methods based on statistical factorial model and rheology of paste model. The procedures, advantages and disadvantages of each method were discussed. The most appropriate method should be chosen according to actual situations to obtain high quality SCC with satisfactory properties.
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•Engineering properties and microstructure of the composites are investigated.•The positive and negative roles of PVA fibres in the composites are revealed.•This study promotes the ...recycling of industrial wastes (GGBFS and FA).•This study serves as an important reference for engineers and designers.
Alkali-activated ground-granulated blast-furnace slag (GGBFS) and fly ash (FA) geopolymers are sustainable alternatives to cement. The incorporation of polyvinyl alcohol (PVA) fibres can help minimise their shortcomings, such as drying shrinkage and brittleness, but may lead to other negative effects. Only a few studies have focused on geopolymer composites based on PVA-fibre-reinforced binary phases (GGBFS and FA). The positive and negative roles of PVA fibres in the performance of composites have not been systemically investigated in previous studies. To promote the application of the composites, the mechanical properties, workability, durability, high-temperature resistance, fibre dispersion, phases, and microstructure of composites with 0, 0.3 and 0.6 vol% of PVA fibres were systematically investigated in this study. The results showed that the incorporation of PVA fibres significantly increased the flexural and splitting tensile strengths of the GGBFS- and FA-blended and single FA-based composites at ambient and high temperatures, and the drying shrinkage was significantly reduced. On the other hand, PVA fibre incorporation caused a decrease in the compressive strength, flowability, consistency, sorptivity, and chloride penetration of the composites; however, the values are still acceptable in construction. Compared to the single FA-based composites, the GGBFS- and FA-blended composites showed improved mechanical properties, sorptivity, chloride resistance, and high-temperature resistance owing to their decreased porosity. This study serves as an important reference for engineers and designers for the use of green composites.
As the fossil fuels are depleting day by day, there is a need to find out an alternative fuel to fulfill the energy demand of the world. Biodiesel is one of the best available resources that have ...come to the forefront recently. In this paper, a detailed review has been conducted to highlight different related aspects to biodiesel industry. These aspects include, biodiesel feedstocks, extraction and production methods, properties and qualities of biodiesel, problems and potential solutions of using vegetable oil, advantages and disadvantages of biodiesel, the economical viability and finally the future of biodiesel. The literature reviewed was selective and critical. Highly rated journals in scientific indexes were the preferred choice, although other non-indexed publications, such as Scientific Research and Essays or some internal reports from highly reputed organizations such as International Energy Agency (IEA), Energy Information Administration (EIA) and British Petroleum (BP) have also been cited. Based on the overview presented, it is clear that the search for beneficial biodiesel sources should focus on feedstocks that do not compete with food crops, do not lead to land-clearing and provide greenhouse-gas reductions. These feedstocks include non-edible oils such as Jatropha curcas and Calophyllum inophyllum, and more recently microalgae and genetically engineered plants such as poplar and switchgrass have emerged to be very promising feedstocks for biodiesel production.
It has been found that feedstock alone represents more than 75% of the overall biodiesel production cost. Therefore, selecting the best feedstock is vital to ensure low production cost. It has also been found that the continuity in transesterification process is another choice to minimize the production cost. Biodiesel is currently not economically feasible, and more research and technological development are needed. Thus supporting policies are important to promote biodiesel research and make their prices competitive with other conventional sources of energy. Currently, biodiesel can be more effective if used as a complement to other energy sources.
•A critical review for Dielectrophoresis (DEP)-based hybrid devices.•A detailed theory and operating procedures of DEP-passive and DEP-active hybrid approaches are presented.•The advantages and ...limitations of each hybrid method are discussed.•Future directions in hybrid-based microfluidic platforms are proposed.
Particle separation is essential in a broad range of systems and has several biological applications. Microfluidics has emerged as a potentially transformational method for particle separation. The approach manipulates and separates particles at the micrometer scale by using well-defined microstructures and precisely managed force fields. Depending on the source of the principal manipulating forces, particle manipulation and separation in microfluidics may be classified as active or passive. Passive microfluidic devices depend on drag and inertial forces and microchannel structure, while active microfluidic systems rely on external force fields. Active microfluidics, in general, can properly control and place particles of interest in real time. Due to the low flow rate, the residual time required to apply an appropriate external manipulating force to the target particles is reduced, thereby limiting overall throughput. Passive microfluidics, on the other hand, has a simple architecture, robustness, and high throughput. Hybrid techniques, which combine active and passive processes, have been created to address the shortcomings of each while maximizing the benefits of each. Numerous hybrid techniques for particle separation have been developed. This study reviews the most recent developments in the field of hybrid devices based on dielectrophoresis. Dielectrophoresis-passive and dielectrophoresis-active hybrid approaches are described and evaluated. Dielectrophoresis-inertial, dielectrophoresis-hydrophoresis, dielectrophoresis- deterministic lateral displacement, and insulator-based dielectrophoresis are examples of dielectrophoresis-passive hybrid devices. Dielectrophoresis with acoustophoresis, magnetophoresis, and optophoresis are examples of dielectrophoresis-active devices. Each hybrid system will be assessed based on its operating principles, advantages, and disadvantages. Following that, a comprehensive explanation of dielectrophoresis physical concepts and operating procedures will be offered. As part of this review, the advantages and disadvantages of DEP-based separation devices will be examined. All these hybrid devices will be thoroughly examined and evaluated. Finally, a summary of present difficulties in the hybrid separation sector will be offered, as well as future suggestions and aspirations.
Fundamentals of soil stabilization Firoozi, Ali Akbar; Guney Olgun, C.; Firoozi, Ali Asghar ...
International journal of geo-engineering,
12/2017, Letnik:
8, Številka:
1
Journal Article
Recenzirano
Odprti dostop
Clayey soils are usually stiff when they are dry and give up their stiffness as they become saturated. Soft clays are associated with low compressive strength and excessive settlement. This reduction ...in strength due to moisture leads to severe damages to buildings and foundations. The soil behavior can be a challenge to the designer build infrastructure plans to on clay deposits. The damage due to the expansive soils every year is expected to be $1 billion in the USA, £150 million in the UK, and many billions of pounds worldwide. The damages associated with expansive soils are not because of the lack of inadequate engineering solutions but to the failure to identify the existence and magnitude of expansion of these soils in the early stage of project planning. One of the methods for soil improvement is that the problematic soil is replaced by suitable soil. The high cost involved in this method has led researchers to identify alternative methods, and soil stabilization with different additives is one of those methods. Recently, modern scientific techniques of soil stabilization are on offer for this purpose. Stabilized soil is a composite material that is obtained from the combination and optimization of properties of constituent materials. Adding cementing agents such as lime, cement and industrial byproducts like fly ash and slag, with soil results in improved geotechnical properties. However, during the past few decades, a number of cases have been reported where sulfate-rich soils stabilized by cement or lime underwent a significant amount of heave leading to pavement failure. This research paper addressed the some fundamental and success soil improvement that used in civil engineering field.
Flavoured and fortified olive oils - Pros and cons Lamas, Sandra; Rodrigues, Nuno; Peres, António M. ...
Trends in Food Science & Technology,
June 2022, 2022-06-00, 20220601, Letnik:
124
Journal Article
Recenzirano
Odprti dostop
Flavouring and fortifying virgin olive oils is an increasing commercial trend, aiming to meet new consumers' preferences and provide new differentiated products. These practices usually positively ...impact the oils’ sensory profile and chemical composition, increasing their natural richness on bioactive compounds. However, some negative effects have also been reported.
This review provides a summary of common flavouring/fortification techniques as well as of the usual natural agents used. Co-extraction, contact and essential oils incorporation techniques are addressed. Usually, flavouring/fortification enhances desirable sensory sensations, and shelf-life, and promotes the incorporation of bioactive compounds like antioxidants. Also, the excess of flavouring may promote the appearance of unpleasant sensory sensations and, in some cases, results in pro-oxidant activity. Fortification, in turn, involves the incorporation of extracts rich in bioactive compounds, contributing to the nutritional and healthy enrichment of the olive oil. However, fortification may also increase the oil's turbidity and/or promote the appearance of unpleasant sensory sensations, resulting in a less appealing oil, hindering the consumers' purchasing.
Although traditional in the Mediterranean, olive oil flavouring or fortification may have positive/negative effects at chemical and sensory levels. This awareness is of paramount commercial importance and can be used as a decision-maker tool for olive oil producers. Thus, the advantages/disadvantages of the different methodologies are discussed, and some perspectives and possible future directions are proposed and briefly discussed.
•Olive oil flavouring is a traditional practice in the Mediterranean region.•Aromatic plants, fruits, spices and olive tree leaves are the usual flavouring agents.•Flavouring by contact and co-extraction are the most common techniques.•Flavouring and/or fortification aims to enhance the olive oil overall quality.•Positive and negative effects on the oils chemical-sensory quality are reported.
Developing countries are faced with a lot of challenges in providing high-quality financial reports based on modern accounting regulations and practices. With its specific colonial and postcolonial ...history of socioeconomic relations, Sudan is one of a few countries that has not adopted the International Financial Reporting Standards (IFRS) either as a mandatory or as a voluntary financial reporting framework. Focusing on a sample of 142 respondents, the attitudes towards the obstacles and possible benefits of introducing the IFRS in Sudan expressed by accountants working in the industry sector are examined in the paper. This research study has shown that Sudanese accountants are highly aware of the needs and benefits of the IFRS adoption. The respondents predominantly agree that the IFRS adoption would increase the FDI inflow, reduce frauds and other unlawful activities, and improve the comparability, reliability and transparency of financial information, which currently is not the case. However, the research shows that accountants in Sudan also express a high degree of skepticism, given the numerous restrictions that they believe would make the introduction of the IFRS more difficult.
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