Effect of waste matrix for the optimization of moisture content and calorific value of biodried material using Taguchi DOE

In this study, Taguchi approach was used to determine the influence of waste composition for the optimization of moisture content (MC) and calorific value (CV) of food waste via bio-drying process. The objective was to reduce MC and increase CV of the bio-dried material. The effect of three different levels of four factors including food (FW), paper (Pa), plastic (Pl) waste, and bulking agent (BA) were studied and optimized. The moisture content of the bio-dried material varied between 8.59 and 50.93%, whereas that of the calorific value was 11–25?MJ/kg. The results revealed optimum configurations for MC and CV as FW₁Pa₃Pl₃BA₃ and FW₁Pa₁Pl₃BA₁, respectively. Regression analysis revealed MC as a positive function of FW and BA with plastic positively correlated with calorific value. ANOVA analysis indicated that FW had more prominent effect on both MC and CV. The predicted and measured values were very close to each other. Additionally, the results realized in the confirmatory experiments at optimized conditions of CV was found to be higher than the test runs of Taguchi design, suggesting that Taguchi method was very successful in the optimization of bio-drying factors for MC and CV.     

The Effect of Axial Wall Conduction on Heat Transfer Parameters for a Parallel-Plate Channel Having a Step Change in Boundary Conditions

This article investigates the effect of an axial wall condition on the heat transfer characteristics for laminar flow through a thick-walled channel. A partition separates the channel of interest into two regions (upstream and downstream region), in which two different coolant fluids bind the channel in those regions. A numerical model was developed using a finite-difference technique to solve the conjugate heat transfer problem. The theoretical model was verified by comparing the predicated results with those obtained from the available analytical and experimental data, and good agreement was achieved. The wall thickness ratio, Biot number, and coolant fluids’ temperature difference step change were selected as the key parameters. The study shows that the significant change in those parameters could lead to an enhancement of 24% for the average Nusselt number at certain conditions.     

Effect of dietary conjugated linoleic acid, irradiation, and packaging conditions on the quality characteristics of raw broiler breast fillets

Skinless breast fillets were harvested from broilers fed with 0, 0.25, 0.5, or 1.0% conjugated linoleic acid (CLA) for 3 weeks. Fillets were either vacuum or aerobically packaged, then irradiated at 0 or 3.0 kGy using a Linear Accelerator. Breast fillets were analyzed for thiobarbituric acid reactive substances (TBARS), volatile profiles, and color at 0 and 7 days of storage at 4°C. Dietary CLA reduced TBARS, but had no effect on volatile profiles and color of breast fillets. Color a* value of breast fillets increased after irradiation. Irradiation also induced production of many volatiles, mainly alkanes and alkenes, which could be the breakdown products of unsaturated fatty acids and amino acids. High amount of dimethyl disulfide was detected in the volatiles of irradiated fillets. Low level of hexanal and pentanal in volatiles, together with low TBARS values, indicated that lipid oxidation of breast fillets after irradiation is not a big concern.     

Silver-filled polyethersulfone membranes for antibacterial applications — Effect of PVP and TAP addition on silver dispersion

Silver-filled asymmetric polyethersulfone (PES) membranes were prepared by a simple phase inversion technique. The effects of polyvinylpyrrolidone (PVP) and 2, 4, 6-triaminopyrimidine (TAP) on the surface properties of the silver-filled asymmetric membrane were investigated for antibacterial application. The dispersion of silver nanoparticles (Ag) and silver content on membrane surface were characterized using field emission scanning electron microscope (FESEM) and energy dispersive spectrometer (EDS), respectively. Results showed that smaller silver particles were formed in PES membranes when PVP and TAP were added during dope preparation. Using inductively coupled plasma mass spectrometry (ICP-MS), it is found that silver leaching has been significantly reduced up to 57% and 63% upon the addition of PVP and TAP respectively. The improved silver dispersion on membrane surfaces was able to enhance the antibacterial activity against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) as evidenced by larger inhibition ring in agar diffusion method. The filtration of E. coli suspension (optical density = 0.31 at λ = 600 nm) carried out on prepared membranes proved that PES-AgNO₃ with TAP as dispersant appeared to inhibit almost 100% bacterial growth in rich medium. Hence, overall results showed the potential of PES-AgNO₃ with TAP to be used for antibacterial applications especially in water treatment.     

Preparation and gas transport properties of dual‐layer polysulfone membranes for high pressure CO2 removal from natural gas

Permeability, sorption, and plasticization behaviors of dual‐layer composite membrane were studied. Polysulfone containing 10.7 wt % glycerol as additive was used for preparing a microporous membrane support. A thin top selective layer was prepared using diethylene glycol dimethyl ether as casting solvent. The overall performance of the membrane was evaluated using Scanning Electron Microscopy, and permeation and sorption tests at pressure up to 50 bar. The prepared membrane displayed high permeability at low pressure which gradually decreased with increase in pressure. Permeability of CO₂ was determined to be 84.97 Barrer at 2 bar. Membrane did not show any plasticization tendency up to the experimental pressure of 40 bar. Plasticization pressure and permeability at plasticization pressure were estimated to be 41.07 bar and 6.03 Barrer, respectively. The improved performance of the membrane is associated to the synergistic properties of the two layers prepared from different formulations of the same polymer. Thus, the dual‐layer flat sheet configuration displayed a potential in high pressure CO₂ removal from natural gas. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40924.     

Epitaxial Growth of Oriented Metalloporphyrin Network Thin Film for Improved Selectivity of Volatile Organic Compounds

This study reports an oriented and homogenous cobalt‐metalloporphyrin network (PIZA‐1) thin film prepared by liquid phase epitaxial (LPE) method. The thickness of the obtained thin films can be well controlled, and their photocurrent properties can also be tuned by LPE cycles or the introduction of conductive guest molecules (tetracyanoquinodimethane and C₆₀) into the PIZA‐1 pores. The study of quartz crystal microbalance adsorption confirms that the PIZA‐1 thin film with [110]‐orientation presents much higher selectivity of benzene over toluene and p‐xylene than that of the PIZA‐1 powder with mixed orientations. These results reveal that the selective adsorption of volatile organic compounds highly depends on the growth orientations of porphyrin‐based metal‐organic framework thin films. Furthermore, the work will provide a new perspective for developing important semiconductive sensing materials with improved selectivity of guest compounds.     

Approximate Analytical Solution of Stagnation Point Flow and Heat Transfer over an Exponential Stretching Sheet with Convective Boundary Condition

This study is concerned with the stagnation point flow and heat transfer over an exponential stretching sheet via an approximate analytical method known as optimal homotopy asymptotic method (OHAM). The governing partial differential equations are converted into ordinary nonlinear differential equations using similarity transformations available in the literature. The heat transfer problem is modeled using two‐point convective boundary condition. These equations are then solved using the OHAM approach. The effects of controlling parameters on the dimensionless velocity, temperature, friction factor, and heat transfer rate are analyzed and discussed through graphs and tables. It is found that the OHAM results match well with numerical results obtained by Runge–Kutta Fehlberg fourth‐fifth order method for different assigned values of parameters. The rate of heat transfer increases with the stretching parameter. It is also found that the stretching parameter reduces the hydrodynamic boundary layer thickness whereas the Prandtl number reduces the thermal boundary layer thickness.     

Synthesis of BaFe12O19 by solid state method and its effect on hydrogen storage properties of MgH2

Previous studies have shown that ferrites give a positive effect in improving the hydrogen sorption properties of magnesium hydride (MgH₂). In this study, another ferrite, i.e., BaFe₁₂O₁₉, has been successfully synthesised via the solid state method, and it was milled with MgH₂ to enhance the sorption kinetics. The result showed that the MgH₂ + 10 wt% BaFe₁₂O₁₉ sample started to release hydrogen at about 270 °C which is about 70 °C lower than the as-milled MgH₂. The doped sample was able to absorb hydrogen for 4.3 wt% in 10 min at 150 °C, while as-milled MgH₂ only absorbed 3.5 wt% of hydrogen under similar conditions. The desorption kinetic results showed that the doped sample released about 3.5 wt% of hydrogen in 15 min at 320 °C, while the as-milled MgH₂ only released about 1.5 wt% of hydrogen. From the Kissinger plot, the apparent activation energy of the BaFe₁₂O₁₉-doped MgH₂ sample was 115 kJ/mol which was lower than the milled MgH₂ (141 kJ/mol)_. Further analyses demonstrated that MgO, Fe and Ba or Ba-containing contribute to the improvement by serving as active species, thus enhancing the MgH₂ for hydrogen storage.