•Operative parameters of HTL substantially influence the property and yield of bio-crude.•HTL produced a higher viscosity bio-crude than pyrolysis.•Apart from the temperature, pressure, biomass to ...solvent ratio altered the bio-crude yield.•Bio-crude generated by HTL scores over pyrolysis except for higher sulphur, yield, and viscosity.•TEA and LCA established variations in yield and properties of fuels with varying operating conditions.
An in-depth, comprehensive, and critical review of the hydrothermal liquefaction (HTL) technology for maximum yield of biocrude with enhanced properties has been undertaken. The feedstocks, process parameters, kinetic of HTL for bio-crude production have been systematically examined and collated from a board range of research. In the coverage of Techno-Economic Analysis (TEA) and Life Cycle Assessment (LCA) of HTL of feedstocks, this review overcomes the failure of existing literature to give due weightage to those crucial issues. HTL is introduced by the direct use of wet biomass that eliminates the drying unit, reduction in total expenditure, and conversion of materials into solid and liquid fuels at moderate temperatures (250–400 °C) and pressures (10–35 MPa). The introduction of hot pressurized water results in a lower yield of tar with higher energy proficiency. The biomass is delineated via elemental composition, renewable feedstock potential, and evaluation of dry versus wet biomass feedstocks. HTL is comprehensively reviewed through the process mechanisms, depolymerization reactions of biomass, hydrothermal liquefaction process of dry and wet lignocellulose feedstocks, and the effect of operating parameters. The product(s) description and evaluation, process advancements, energy efficiency, and kinetic investigation in relation to HTL form the final parts of this review. This review is aimed at optimization and commercialization of the HTL technology to meet the demands of the biofuel sector, the researcher working in the thermochemical conversion of feedstocks, and the development of new HTL reactors.
The objective of image segmentation is to extract meaningful objects. A meaningful segmentation selects the proper threshold values to optimize a criterion using entropy. The conventional multilevel ...thresholding methods are efficient for bi-level thresholding. However, they are computationally expensive when extended to multilevel thresholding since they exhaustively search the optimal thresholds to optimize the objective functions. To overcome this problem, two successful swarm-intelligence-based global optimization algorithms, cuckoo search (CS) algorithm and wind driven optimization (WDO) for multilevel thresholding using Kapur’s entropy has been employed. For this purpose, best solution as fitness function is achieved through CS and WDO algorithm using Kapur’s entropy for optimal multilevel thresholding. A new approach of CS and WDO algorithm is used for selection of optimal threshold value. This algorithm is used to obtain the best solution or best fitness value from the initial random threshold values, and to evaluate the quality of a solution, correlation function is used. Experimental results have been examined on standard set of satellite images using various numbers of thresholds. The results based on Kapur’s entropy reveal that CS, ELR-CS and WDO method can be accurately and efficiently used in multilevel thresholding problem.
The dependence of temperature on the fluorescence lifetime and fluorescence intensity ratio using Stark sublevels and thermally coupled (close lying) levels in triply ionized rare earth ions, doped ...into a variety of glasses and fibers, have been reviewed. Also, it is claimed that not only for the two closely lying levels of triply ionized rare earth ion of the same kind, but also for two different triply ionized rare earth ions, having their excited levels very close to each other, may be used to monitor the temperature.
The use of nanoemulsion in augmenting dermal and transdermal effectiveness of drugs has now well established. The development of nanoemulsion based semisolid dosage forms is an active area of present ...research. However, thickening or liquid-to-semisolid conversion of the nanoemulsions provides opportunities to the formulation scientist to explore novel means of solving instability issues during transformation. Extending knowledge about the explicit role of nature/magnitude of zeta potential, types of emulsifiers and selection of appropriate semisolid bases could place these versatile carriers from laboratory to industrial scale. This article reviews the progressive advancement in the delivery of medicament via nanoemulsion with special reference to the dermal and transdermal administration. It is attempted to explore the most suitable semi solid dosage form for the particular type of nanoemulsion (o/w, w/o and others) and effect of particle size and zeta potential on the delivery of drugs through dermal or transdermal route. Finally, this review also highlights the basic principles and fundamental considerations of nanoemulsion manufacture, application of nanoemulsion based semisolid dosage forms in the dermal/transdermal administration and basic considerations during the nanoemulsion absorption into and through skin.
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In this study, for the first time, the approximate solution of Black–Scholes option pricing distributed order time-fractional partial differential equation by means of Legendre and Chebyshev wavelets ...is considered. The operational matrices of Legendre and Chebyshev wavelets for integer order derivative and distributed order fractional derivative are derived. Furthermore, the combination of Gauss–Legendre quadrature formula and standard Tau method along with the obtained operational matrices reduces the distributed order time-fractional Black–Scholes model (DOTFBSM) into the system of linear algebraic equations. Convergence analysis, error bounds and numerical stability of the proposed approach are discussed in detail. The presented scheme is applied on three test examples and numerical experiments confirm the theoretical results and illustrate robustness of the presented method. The results produced by current approach are found to be more accurate than some available results.
Volatile organic compounds (VOCs) encompass hundreds of high production volume chemicals that have been used in a wide range of household and industrial products. Widespread use of products that ...contain VOCs resulted in their ubiquitous occurrence in the environment, with elevated concentrations frequently found in indoor environments. Human exposure to VOCs is pervasive and has been a topic of concern, due to the mutagenic, neurotoxic, genotoxic, and carcinogenic potentials of these chemicals. Although several previous articles described toxic effects of VOCs, relatively less is known on their human exposure and body burdens. VOCs have been determined in human breath condensate, blood, feces, and urine. This review updates the information on the environmental occurrence, toxicity, sources and pathways of human exposure, metabolism and elimination, and biomonitoring of exposure to VOCs. Indoor air is a major source of human exposure to VOCs. Higher atmospheric concentrations of VOCs have been reported in Asian countries than in North American and European countries. Elevated concentrations of four widely studied VOCs namely, benzene, toluene, ethylbenzene and xylene (BTEX) were reported in air from newly constructed or renovated homes (1.3–350 μg/m3) and e-waste workshops (2.45–3,10,000 μg/m3). BTEX were also found in consumer products such as shoe polish, whiteout, leather cleaner and ink at notable concentrations (e.g., ~92,600 μg/g). Traditional methods of exposure assessment of VOCs entailed measurement of these chemicals in indoor air and determination of inhalation exposure dose. SStudies on VOC exposure assessment mainly focused on occupationally exposed individuals. Recent developments in biomonitoring of urinary metabolites of VOCs present accurate assessment of exposures and internal body burdens. Biomonitoring studies of VOCs offer novel biomarkers for the assessment of airway inflammation, lung injury, neurological disorders, immune dysfunction and cancers in populations. Considering the very high production volume (at billions of pounds annually), known toxicity, and widespread human exposures, significance of VOCs in eliciting adverse health effects in populations will be a subject of increasing public health concern for years to come.
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•VOCs are found at higher levels in indoor air (10s to 100s of μg/m3 ) than in outdoor air.•Besides carcinogenicity, VOCs are potent central nervous system toxicants.•VOCs are metabolized quickly and yield several toxic metabolites that are excreted in urine.•Up to 38 VOC metabolites can be measured in urine at concentrations of hundreds to thousands of ng/mL.•Urinary VOC metabolites are valuable biomarkers to link health effects of these chemicals.
Sugarcane-molasses-based post-methanated distillery waste is well known for its toxicity, causing adverse effects on aquatic flora and fauna. Here, it has been demonstrated that there is an abundant ...mixture of androgenic and mutagenic compounds both in distillery sludge and leachate. Gas chromatography-mass spectrometry (GC-MS) analysis showed dodecanoic acid, octadecanoic acid,
-pentadecanoic acid, hexadecanoic acid, β-sitosterol, stigmasterol, β-sitosterol trimethyl ether, heptacosane, dotriacontane, lanosta-8, 24-dien-3-one, 1-methylene-3-methyl butanol, 1-phenyl-1-propanol, 5-methyl-2-(1-methylethyl) cyclohexanol, and 2-ethylthio-10-hydroxy-9-methoxy-1,4 anthraquinone as major organic pollutants along with heavy metals (all mg kg
): Fe (2403), Zn (210.15), Mn (126.30, Cu (73.62), Cr (21.825), Pb (16.33) and Ni (13.425). In a simultaneous analysis of bacterial communities using the restriction fragment length polymorphism (RFLP) method the dominance of
sp. followed by
sp. as autochthonous bacterial communities growing in this extremely toxic environment was shown, indicating a primary community for bioremediation. A toxicity evaluation showed a reduction of toxicity in degraded samples of sludge and leachate, confirming the role of autochthonous bacterial communities in the bioremediation of distillery waste
.
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•GDY function as co-catalyst and anchored nanoparticles to enhance the stability.•Basic structure and properties of GDY were elaborated.•The recent development in synthetic methods ...and different morphology of GDY were considered.•GDY nanocomposites for photodegradation, CO2 reduction, hydrogen evolution were explored.•Lastly, conclusion and future prospects of research on GDY-based nanomaterials.
Carbon materials are inexpensive and high‐performance nanomaterials producing ample scope for versatile applications. Graphdiyne (GDY) is a two-dimensional allotrope of carbon having sp and sp2 hybridized planar carbon atoms. GDY was firstly synthesized by Li and co-workers in 2010, having diacetylene linkages, conjugated system, wide surface spacing, and pores distribution, tunable electronic properties, good chemical stability, and semiconductor characteristics. In this review, we examine GDY properties, synthesis, bandgap tunability, and current advancement in photocatalytic applications. Recent modifications in electrical, optical, and magnetic properties and some strategies to alter the bandgap of GDY, including applying strain, doping, co-doping, morphology formulation, and heterojunction construction, are elaborated. Different structural and morphological analysis, including nanotube, nanowires, nanosheets, nanowalls, and 3D GDY framework, are also discussed. Earlier GDY studies based on theoretical analysis are being validated by experimentation for feasible photocatalytic applications. The GDY-based nanocomposites were extensively explored for photodegradation, photoreduction of CO2, photocatalytic hydrogen production. The focus of this review is to provide an in‐depth understanding of GDY and promote the advancement in the development of next-generation photocatalytic systems derived from carbon materials.
The presence of arsenic and fluoride in groundwater has been observed throughout the world. Many technologies have been developed by various research groups in order to tackle this problem. ...Adsorption has emerged as one of the best possible technique for the removal of arsenic, fluoride and many other pollutants from drinking water. Although a considerable amount of work has been published on the adsorptive removal of arsenic and fluoride, the area related to the management of spent adsorbent is not well explored. Present paper deals with the adsorptive removal of arsenic and fluoride from aqueous solution by three different types of adsorbents, namely, thermally treated laterite (TTL), acid-base treated laterite (ABTL) and aluminum oxide/hydroxide nanoparticles (AHNP). Under the experimental conditions in batch operation, the adsorption capacities of TTL, ABLT and AHNP for arsenic are found to be 6.43 μg/g, 9.25 μg/g and 48.5 μg/g respectively, whereas for fluoride, these values are found as 0.21 mg/g, 0.85 mg/g and 4.65 mg/g respectively. After adsorption, the spent adsorbents have been stabilized in the form of clay bricks. The effects of spent adsorbent concentration on the properties of bricks and their leaching properties are investigated. The bricks have been tested for various properties like density, percentage water absorption, shrinkage, compressive strength and efflorescence. The maximum values of density and shrinkage of the bricks formed are found as 2.3 g/cm3 and 10.2%, whereas the percentage water absorption and compressive strength of the bricks are found between 11 and 14% and 35 to 150 kgf/cm2 respectively. All the test results are in accordance with the criteria set by Indian Standards. The leaching test of arsenic and fluoride from the bricks reveals that their maximum values in leachate are 510 μg/L and 2.1 mg/L respectively, which are below the permissible limits of USEPA standards.
•Preparation and characterization of three different adsorbents for simultaneous removal of As and F.•Immobilization of spent adsorbent in the form of clay bricks.•Effect of ratio of spent adsorbent to clay and sintering temperature on brick properties and leaching of As and F.
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