Sustainable use of biofuel by recycling ash to forests: treatment of biofuel ash

The influence of treatment techniques on leaching properties of alkaline species from biofuel ash is investigated in this paper. Ash samples from combustion of biofuels in a circulating fluidized bed and grate-firing combustion plants are studied. The samples are treated using three different treatment techniques; self-hardening, thermal treatment, and hardening bythe addition of binding materials. Nontreated and treated samples are evaluated for the leaching properties of the alkaline compounds and, furthermore, are characterized with respect to both physical and chemical characteristics. The results show the influence of treatment techniques on the physical structure and leaching characteristics of alkaline species. Results also indicate that ash samples show different behavior when treated with different methods, i.e., the influence of treatment technique on controlling the leaching properties is highly dependent on the initial chemical composition of ash. It was also found that there is an interaction between leaching of limited and easily soluble species, e.g., calcium and potassium leaching. Therefore, to control the leaching rate of alkaline species from ash, the characteristics that correlate the leaching properties of both easily and limited soluble species need to be adjusted.     

Structure–properties-performance relationships in complex epoxy nanocomposites: A complete picture applying chemorheological and thermo-mechanical kinetic analyses

Herein the kinetics of network formation (cross-linking) and network degradation (thermal decomposition) in a complex system based on epoxy resin reinforced with hyperbranched amino polymer-functionalized nanoparticles (HAPF) were discussed. Five classes of nanoparticles, that is, nano-SiO₂, halloysite nanotubes (HNTs), HNTs@nano-SiO₂ core/shell, HAPF/nano-SiO₂, HAPF/HNTs@nano-SiO₂ core/shell were loaded at 0.5, 1.0, 2.0 (optimal loading among prepared samples), and 5 wt% were examined. Parameters of the cure kinetics and degradation were correlated, and the mechanical properties were interpreted in terms of microstructure and rheological analyses. The isothermal chemorheological cure kinetics study (60, 70, and 80°C) revealed a low activation energy for epoxy/HAPF/HNTs@nano-SiO₂ core/shell nanocomposite (72.21 kJ/mol), compared with the blank epoxy (79.99 kJ/mol). Correspondingly, gel time of the system decreased from 1040 to 515 to 237 s upon isotherms of 60, 70, and 80°C, respectively. Tensile strength was also increased vividly (ca. 32%), possibly due to the strong interfacial adhesion, which reflected in an induced shear yielding. Nitrogen-mediated thermal decomposition kinetics suggested an average degradation activation energies of ca. 150 and 210 kJ/mol for the assigned nanocomposites and the blank epoxy, respectively. Overall, there was a complete agreement between the kinetics of network formation and network degradation in the studied epoxy nanocomposite. This work enables understanding of structure-properties-performance in complex epoxy nanocomposites.     

An investigation of water-flow pressure distribution on bridge piers under flood loading

This study simulates the flood effect on piers using a finite volume method in the ANSYS-FLUENT package. The pier is modelled as a non-structural column with a rectangular and a circular cross-section. To simplify the methodology, the pier, as well as the bed and side walls, is assumed to have non-slip boundaries for the fluid domain. A crucial feature of this investigation is the consideration of the effect of water while it is flowing around an object like a bridge pier and the distribution of pressure along the pier height. A numerical model is proposed to explore the influence of variation of velocity on the hydrodynamic force and pressure distribution exerted on piers. A significant finding is that the shape of the pier cross-section has a significant effect on the fluid pressure exerted on bridge piers under flood loading. It is noted that the AS5100 method is appropriate for a conservative estimation of the pressure on rectangular piers, whereas the technique will have a risky safety margin for bridge piers with a circular cross-section and need to be used with caution.     

Piperine—The Bioactive Compound of Black Pepper: From Isolation to Medicinal Formulations

Piperine is the major bio‐active component of pepper, which imparts pungency and biting taste to it. This naturally occurring alkaloid has numerous demonstrated health effects and beneficial therapeutic properties; nevertheless, its biological applications are limited due to its poor solubility in aqueous environments. This emphasizes an implementation of advanced extraction approaches which could enhance the extraction yield of piperine from pepper and also the development of new formulations containing piperine to improve its in vivo bioavailability. This paper presents a review on the therapeutic and medicinal effects of piperine, its isolation from pepper fruit and the development of new formulations for its medicinal (pharmaceutical) applications. A thorough review on conventional and advanced separation techniques for the extraction of piperine from pepper is presented and an outline of the most significant conditions to improve the extraction yield is provided and discussed. Different methods used to measure and quantify the isolated piperine are also reviewed. An overview of biotechnological advancements for nanoparticle formulations of piperine or its incorporation in lipid formulations, which could enhance its bioavailability, is also presented.     

Kinetic study of CO hydrogenation over co-precipitated iron–nickel catalyst

The kinetic of the Fischer–Tropsch synthesis over a Fe–Ni/Al₂O₃ catalyst was investigated in a fixed bed micro reactor. Experimental conditions were varied as follow: reaction pressure 2–10 bar, H₂/CO feed ratio of 2/1 and space velocity of 96–450 cm³(STP)/h/gram_catalyst at the temperature range 523–573 K. On the basis of carbide-enol mechanism and Langmuir–Hinshelwood–Hougen–Watson (LHHW) type rate equations, seventeen kinetic expressions for CO consumption were tested and interaction between adsorption HCO and dissociated adsorption hydrogen as the controlling step gave the most plausible kinetic model. The activation energy was 46.5 kJ/mole for optimal kinetic model.     

Synthesis and application of amine functionalized silica mesoporous magnetite nanoparticles for removal of chromium(VI) from aqueous solutions

In this research, novel nanoparticles of Kit-6 mesoporous silica magnetite were synthesized with 9.6 nm pore diameter and 241.68 m² g^?1 surface area. The synthesized mesoporous magnetite nanoparticles (MMNPs) were functionalized with amine groups. Scanning electron microscopy, powder X-ray diffraction, Fourier transform infrared spectroscopy and nitrogen adsorption–desorption method confirmed the morphology and structure of the synthesized nanoparticles. The amine functionalized MMNPs were used for sorption of toxic chromate ions from aqueous samples. The effect of various experimental parameters (four factors at three levels) on the sorption efficiency of Cr(VI) was studied and optimized via Taguchi L₉ (3⁴) orthogonal array experimental design. At optimum conditions, the sorption of the Cr(VI) was best described by a pseudo second-order kinetic model with R² = 0.9999 and q_eq = 129.8 mg g^?1, suggesting chemisorption mechanism. Adsorption data were fitted well to the Langmuir isotherm and the synthesized sorbent showed complete ion removal with 185.2 mg g^?1sorption capacity.     

Experimental and numerical studies on bubble dynamics in nonpressurized foaming systems

This work explores the influence of rheological properties on polymer foam development in nonpressurized systems. To understand the complex contributions of rheology on the mechanism of bubble growth during different stages of foam processing, visualization studies were conducted by using a polymer‐foaming microscopy setup. The evolving cellular structure during foaming was analyzed for its bubble surface density, bubble size, total bubble projected area, and bubble size distribution. Morphological analysis was used to determine the rheological processing window in terms of shear viscosity, elastic modulus, melt strength and strain‐hardening, intended for the production of foams with greater foam expansion, increased bubble density and reduced bubble size. A bubble growth model and simulation scheme was also developed to describe the bubble growth phenomena that occurred in nonpressurized foaming systems. Using thermophysical and rheological properties of polymer/gas mixtures, the growth profiles for bubbles were predicted and compared to experimentally observed data. It was verified that the viscous bubble growth model was capable of depicting the growth behaviors of bubbles under various processing conditions. Furthermore, the effects of thermophysical and rheological parameters on the bubble growth dynamics were demonstrated by a series of sensitivity studies. POLYM. ENG. SCI., 54:1947–1959, 2014. © 2013 Society of Plastics Engineers     

Multiobjective optimization of polymerization reaction of vinyl acetate by genetic algorithm technique with a new replacement criterion

A multiobjective optimization procedure based on genetic algorithm has been developed to determine optimum operational conditions of polymerization reaction. In this article by using a new selection criterion to choose the next generation members with better quality, optimization efficiency is improved and the number of generations to obtain Pareto optimal set reduced. In this proposed method a novel replacement criterion based on ranking level information and proximity of solutions to the Pareto optimal front is used to choose the next generation members. The polymerization of vinyl acetate has been chosen as an example. Two objective functions, which used in this study, are maximization of the weight average molecular weight up to the desired value and minimization of the residual initiator concentration. A Pareto optimal set of objective functions has been obtained by application of a Pareto set filter operator. Furthermore, the influence of genetic algorithm parameters on the efficiency and convergence of genetic algorithm is studied by changing cross over and mutation probabilities. Because of the flexibility and generality of genetic algorithm, this optimization method is a useful technique with lots of potentials in determination of optimum value of operation parameters. POLYM. ENG. SCI., 2008. © 2008 Society of Plastics Engineers     

Impact of the wet spinning parameters on the alpaca-based polyacrylonitrile composite fibers: Morphology and enhanced mechanical properties study

The study examined the effect of different wet spinning parameters (e.g., total solid content, coagulation bath concentration, drawing, and stretching) on the morphology and mechanical properties of the wet spun alpaca/polyacrylonitrile (PAN) composite fibers. The alpaca/PAN composite fibers were wet spun using 10, 20, and 30% of alpaca particles along with the PAN polymer. The shear-thinning or non-Newtonian flow behavior was observed among the dope solutions with different solid content. The cross-sectional fiber morphology showed the bean-shaped characteristic for the control PAN fibers, whereas the alpaca/PAN composite fibers exhibited almost circular shape. “Cavity healing” was observed, where noticeable voids and porous areas were demolished in the cross section of the composite fibers, by changing the total solid content and coagulation bath concentration. Although the control PAN fibers exhibited the highest tenacity with lower fiber diameter, the alpaca/PAN composite fibers showed a gradual deterioration in tenacity while adding alpaca particles into the PAN polymeric matrix. Nevertheless, due to the increment in the total solid content, higher draw ratio, and stretching of the fibers, the tenacity, molecular orientation, and the crystallinity of the composite fibers were increased.     

Energy harvesting,cooperative spectrum sensing,and data transmission improvement in energy‐efficient multichannel cognitive sensor networks

In this paper, we investigate the energy harvesting capability in a multichannel wireless cognitive sensor networks for energy‐efficient cooperative spectrum sensing and data transmission. Spectrum sensors can cooperatively scan the spectrum for available channels, whereas data sensors transmit data to the fusion center (FC) over those channels. We select the sensing, data transmission, and harvesting sensors by setting the sensing time, data transmission time, and also harvesting time to maximize the network data transmission rate and improve the total energy consumption in the multichannel network under global probability of false alarm and global probability of detection constraints. We formulate our optimization problem and employ the convex optimization method to obtain the optimal times and nodes for spectrum sensing, data transmission, and harvesting energy in each subchannel for multiband cognitive sensor networks. Simulation results show that in our proposed algorithm, the network data transmission rate is improved while more energy is saved compared with the baseline methods with equal sensing time in all subchannels.