Display omitted
•This study examined the potential of waste biorefineries in developing countries.•Waste biorefineries can achieve circular economy, especially in developing countries.•Waste in ...developing countries is a promising source of energy and value-added products.•Selection of waste to energy technologies depend on regional waste characterization.•Decision to select among the types of waste biorefineries requires LCA study.
This paper aims to examine the potential of waste biorefineries in developing countries as a solution to current waste disposal problems and as facilities to produce fuels, power, heat, and value-added products. The waste in developing countries represents a significant source of biomass, recycled materials, chemicals, energy, and revenue if wisely managed and used as a potential feedstock in various biorefinery technologies such as fermentation, anaerobic digestion (AD), pyrolysis, incineration, and gasification. However, the selection or integration of biorefinery technologies in any developing country should be based on its waste characterization. Waste biorefineries if developed in developing countries could provide energy generation, land savings, new businesses and consequent job creation, savings of landfills costs, GHG emissions reduction, and savings of natural resources of land, soil, and groundwater. The challenges in route to successful implementation of biorefinery concept in the developing countries are also presented using life cycle assessment (LCA) studies.
In the Kingdom of Saudi Arabia (KSA), millions of Muslims come to perform Pilgrimage every year. Around one million ton of municipal solid waste (MSW) is generated in Makkah city annually. The ...collected MSW is disposed of in the landfills without any treatment or energy recovery. As a result, greenhouse gas (GHG) emissions and contamination of the soil and water bodies along with leachate and odors are occurring in waste disposal vicinities. The composition of MSW shows that food waste is the largest waste stream (up to 51%) of the total generated MSW. About 13% of the food waste consists of fat content that is equivalent to about 64 thousand tons per year. This study aims to estimate the production potential of biodiesel first time in Makkah city from fat/oil fractions of MSW and highlight its economic and environmental benefits. It has been estimated that 62.53, 117.15 and 6.38 thousand tons of biodiesel, meat and bone meal (MBM) and glycerol respectively could be produced in 2014. A total electricity potential of 852 Gigawatt hour (GWh) from all three sources based on their energy contents, Higher Heating Value (HHV) of 40.17, 18.33 and 19 MJ/kg, was estimated for 2014 that will increase up to 1777 GWh in 2050. The cumulative net savings from landfill waste diversion (256 to 533 million Saudi Riyal (SAR)), carbon credits (46 to 96 million SAR), fuel savings (146 to 303 million SAR) and electricity generation (273 to 569 million SAR) have a potential to add a total net revenue of 611 to 1274 million SAR every year to the Saudi economy, from 2014 to 2050 respectively. However, further studies including real-time data about annual slaughtering activities and the amount of waste generation and its management are critical to decide optimum waste management practices based on life cycle assessment (LCA) and life cycle costing (LCC) methodologies.
•Polystyrene comprises 14.7% of municipal solid waste in Saudi Arabia.•The optimum temperature for pyrolysis was 450°C at 75min retention time.•At optimum conditions liquid fuel was 76% by mass of ...polystyrene.•The liquid fuel had a high energy value of 41.2GJ/t and density (0.92g/cm3).•The liquid fuel had low pour point (−18°C) and freezing point (−64°C).
This paper aims to investigate the effect of temperature and reaction time on the yield and quality of liquid oil produced from a pyrolysis process. Polystyrene (PS) type plastic waste was used as a feedstock in a small pilot scale batch pyrolysis reactor. At 400°C with a reaction time of 75min, the gas yield was 8% by mass, the char yield was 16% by mass, while the liquid oil yield was 76% by mass. Raising the temperature to 450°C increased the gas production to 13% by mass, reduced the char production to 6.2% and increased the liquid oil yield to 80.8% by mass. The optimum temperature and reaction time was found to be 450°C and 75min. The liquid oil at optimum conditions had a dynamic viscosity of 1.77mPas, kinematic viscosity of 1.92cSt, a density of 0.92g/cm3, a pour point of −60°C, a freezing point of −64°C, a flash point of 30.2°C and a high heating value (HHV) of 41.6MJ/kg this is similar to conventional diesel. The gas chromatography with mass spectrophotometry (GC–MS) analysis showed that liquid oil contains mainly styrene (48%), toluene (26%) and ethyl-benzene (21%) compounds.
The complex juvenile/maturity transition during a plant's life cycle includes growth, reproduction, and senescence of its fundamental organs: leaves, flowers, and fruits. Growth and senescence of ...leaves, flowers, and fruits involve several genetic networks where the phytohormone ethylene plays a key role, together with other hormones, integrating different signals and allowing the onset of conditions favorable for stage progression, reproductive success and organ longevity. Changes in ethylene level, its perception, and the hormonal crosstalk directly or indirectly regulate the lifespan of plants. The present review focused on ethylene's role in the development and senescence processes in leaves, flowers and fruits, paying special attention to the complex networks of ethylene crosstalk with other hormones. Moreover, aspects with limited information have been highlighted for future research, extending our understanding on the importance of ethylene during growth and senescence and boosting future research with the aim to improve the qualitative and quantitative traits of crops.
Abstract The Astragalus grahamianus (AG) Royle ex. Benth is traditionally used for the treatment of various human disorders. The current research work is aimed to explore the neuroprotective ...anti-Parkinson effects of various fractions of Astragalus grahamianus (A. grahamianus). Fine powder of Astragalus grahamianus was extracted with 70% methanol and then fractionated with various solvents on the basis of polarity. Standard protocols were used to investigate the bioactive constituents present in the various plant fractions. In-vitro antioxidant potential of various fractions was checked using diverse free radicals. In-vivo rats model was used to determined the neuroprotective effects of methanol fraction of A. grahamianus. The results revealed that various fractions of A. grahamianus contain flavonoids, cardiac glycosides, steroids, gums, terpenes, proteins, and carbohydrates except chloroform fraction lake the presence of steroids, cardiac glycosides, gums and saponins, aqueous fraction of steroids, terpenoids, gums and saponins, n-Hexane fraction steroids, carbohydrates, alkaloids, gums and flavonoids. The highest amount of total phenolic contents was found in AGME (32.67 ± 2.3 mg GAE / g). The AGME also showed enhanced free radicals cations potential against DPPH, ABTS and H2O2, respectively. The correlation between AOA (antioxidant activity) and TPC (total phenolic contents) revealed to be substantial. Relative R2 values for ABTS, H2O2, and DPPH activity are 0.9974, 0.9845, and 0.9678, respectively. The in-vivo neuroprotective activities showed significant results. Our findings highlight significant antioxidant, and neuroprotective possessions of AGME attributed to powerful bioactive compounds.
Resumo O Astragalus grahamianus (AG) Royle ex. Benth pertence à família Fabaceae e o gênero Astragalus é tradicionalmente utilizado para o tratamento de diversas doenças humanas. O presente trabalho de pesquisa tem como objetivo explorar os aspectos benéficos das plantas que estão sendo investigados tanto in vitro, ou seja, antioxidantes, quanto in vivo (seu impacto no comprometimento da memória induzido pela neuroinflamação em ratos). Para tanto, extrato metanólico de A. grahamianus (AGME) e frações com diversos solventes foram sintetizados com base na polaridade. Os resultados revelaram que várias frações de A. grahamianus contêm flavonoides, glicosídeos cardíacos, esteroides, gomas, terpenos, proteínas e carboidratos, exceto a fração de clorofórmio, e a presença de esteroides, glicosídeos cardíacos, gomas e saponinas, fração aquosa de esteroides, terpenoides, gomas e saponinas, esteroides da fração n-hexano, carboidratos, alcaloides, gomas e flavonoides. A maior quantidade de conteúdo fenólico total foi encontrada no AGME (32,67 ± 2,3 mg GAE/g). O AGME também mostrou maior potencial de cátions de radicais livres contra DPPH, ABTS e H2O2. A correlação entre AOA (atividade antioxidante) e TPC (conteúdo fenólico total) revelou-se substancial. Os valores relativos de R2 para atividade ABTS, H2O2 e DPPH são 0,9974, 0,9845 e 0,9678, respectivamente. As atividades neuroprotetoras in vivo mostraram resultados significativos. Nossas descobertas destacam propriedades antioxidantes e neuroprotetoras significativas do AGME atribuídas a poderosos compostos bioativos.
In this study, plant-mediated copper nanoparticles (CuNPs) were synthesized. Due to its direct synthesis mechanism and eco-friendly nature, the current method accounts for the green chemistry ...approach using the fruit extract of
for the first time. The UV-visible spectrum of the CuNPs solution showed a distinct absorption peak at 588 nm. Fourier transform infrared spectroscopy confirmed that the fruit extract is responsible for the reduction as well as the stabilization of CuNPs. X-ray diffraction patterns conform the crystalline nature of CuNPs. Energy-dispersive X-ray spectroscopy was performed for elemental analysis whereas field emission scanning electron microscopy was carried out for surface morphology. Prepared CuNPs were used for the reduction of carcinogenic azo dyes methyl orange (MO) and congo red (CR). CuNPs exhibit outstanding catalytic reduction for MO and CR in the presence of NaBH
as reducing agents with the pseudo-first-order rate constants of 8.6×10
s
and 5.07×10
s
for MO and CR, respectively. Thus, natural plant materials act as cheap and environmentally friendly support for the synthesis of CuNPs and could be used for the purification of water from organic dye effluents.
Substances at nanoscale, commonly known as “nanomaterials,” have always grabbed the attention of researchers for hundreds of years. Among these different types of nanomaterials, magnetic ...nanomaterials have been the focus of considerable attention during the last two decades as evidenced by an unprecedented increase in the number of research papers focusing these materials. Iron oxide magnetic nanoparticles have occupied a vital position in imaging phenomena; as drug vehicles, controlled/sustained release phenomena and hyperthermia; atherosclerosis diagnosis; prostate cancer. In fact, these are wonderful “theranostic” agents with some under clinical trials for human use. In this review, we have attempted to highlight the advances taking place in the field of magnetic nanoparticles as theranostic agents. Extensive progress has been made in the two most important parameters, namely, control over the size and shape which decide the importance of iron oxide magnetic nanoparticles by developing suitable procedures like precipitation, co-precipitation, thermal decomposition, hydrothermal synthesis, microemulsion synthesis and plant mediated synthesis. After using a suitable synthetic route, workers encounter the most daunting task linked with the materials at nanoscale i.e., the protection against corrosion. Only properly protected iron oxide magnetic nanoparticles can be further connected to different functional systems to make building blocks for application in catalysis, biology and medicines. Finally, “theranostics” which is a combined application of imaging and drug delivery has been discussed. With all the potential uses, toxicity of the of iron oxide magnetic nanoparticles has been discussed.
•Comprehensively review the technology for converting waste plastic into transport fuel.•Explain various pyrolysis processes and reactors are used in waste plastic management.•Investigate the quality ...of plastic pyrolytic oil as a fuel and how it performs in an automobile engine.•Identify the technical challenges and opportunities for waste plastic to fuel technology's industrial and commercial application.
Despite extensive research in recent years and great potential to help with energy and waste management issues, thermochemical conversion technologies of mixed waste plastics (MWP) into transport engine fuel have not yet been developed in industrial and commercial settings. This study reviewed, discussed, and summarised research findings of over 280 up to date publications, emphasising pyrolysis technologies and their product yields, qualities, challenges and opportunities. The study investigated the suitability of pyrolysis oil for automobile engine application and summarised the experimental findings of diesel engine performance and emission characteristics. Furthermore, techno-economic assessment and key challenges for commercial fuel production from plastic pyrolysis are discussed. The review found that the pyrolysis of MWP produces oil yields of up to 90% by weight, and excellent fuel properties in the pyrolysis temperature range of 500 °C−550 °C. Polystyrene individually yields the highest oil yield of 97%, followed by low-density polyethylene, high-density polyethylene and polypropylene. However, polyethylene terephthalate and polyvinyl chloride plastics are not suitable for pyrolysis because they produce harmful chlorine gas and HCl that corrode the metallic parts of the pyrolysis reactor and condenser. Engine testing with MWP oil showed delayed combustion, high heat release rate and high cylinder pressure with similar power output and brake thermal efficiency. In contrast, NOx, UHC, CO and CO2 emissions were much higher. The study found that the pyrolysis plants must process at least 50 kT/year to earn an ROI of 25%. Additional research is required to resolve the remaining issues and challenges for industrial and commercial applications.
•A novel intermittent microwave convective drying (IMCD) model was developed.•The model predicted accurately drying process, bioactive compounds and colour changes.•Effects of different IMCD ...conditions on quality changes are discussed.•The model can predict accurately quality indices over a range of IMCD conditions.
Intermittent microwave convective drying (IMCD) is an advanced drying method where volumetric heating of samples drives the drying process. Understanding of the physical effects of IMCD on simultaneous heating and mass transfer as well as quality changes during IMCD is essential to predict accurately drying processes and quality attributes of end products. However, there is a lack of studies in this particular interest area. The aim of this research was to develop an IMCD model coupled with quality degradation kinetics by integrating a simultaneous heat and mass transfer model with Maxwell’s equations for microwave heating and the chemical reaction kinetics model. The simulated results were compared with experimental results and a good agreement was observed. As it was found that power ratio (PR) had a vital role in altering quality attributes, different PR and drying conditions were considered to investigate the effects of IMCD on the drying kinetics. The simulated results showed that the model was capable of predicting accurately moisture and temperature distributions along with heath beneficial compounds, such as total phenolic content (TPC) and ascorbic acid (AA) as well as colour changes during IMCD processing. About 70% of AA was degraded during IMCD drying using PR of 1/3. However, losses were reduced when PR was reduced to 1/4 or 1/5. Likewise, TPC degraded significantly during the early stages (first 60 min) of IMCD processing but stabilised at later stages.
PDF
