Biodiesel production from waste cooking oil over alkaline modified zirconia catalyst

Screening and catalytic activity of alkaline modified zirconia i.e. Mg/ZrO₂, Ca/ZrO₂, Sr/ZrO₂, and Ba/ZrO₂ as heterogeneous catalyst in biodiesel production from waste cooking oil (WCO) have been investigated. The catalysts were prepared via wet impregnation of alkaline nitrate salts supported on zirconia. Physico-chemical characteristics of the catalysts were analyzed by BET surface area, XRD, FESEM and CO₂–NH₃–TPD. Among the catalysts screened, Sr/ZrO₂ exhibited higher catalytic activities. Characterization results disclosed Sr/ZrO₂ catalyst possessed balanced basic and acid site concentrations with its pore volume, surface area as well as pore diameters suitable for biodiesel production. The balanced active sites facilitated simultaneous transesterification and esterification of WCO. A plausible mechanism has been suggested for the simultaneous reactions. The effects of operating process conditions such as methanol to oil molar ratio, reaction temperature and catalyst loading on biodiesel production in the presence of Sr/ZrO₂ were investigated. Methyl ester (ME) yield at 79.7% was produced over 2.7 wt.% catalyst loading (Sr/ZrO₂), 29:1 methanol to oil molar ratio, 169 min of reaction time and 115.5 °C temperature.     

A Two-stage Immobilized Cell Bioreactor With Bacillus subtilis and Rhodococcus erythropolis for the Simultaneous Production of Biosurfactant and Biodesulfurization of Model Oil

Two vertical rotating immobilized cell reactors (VRICRs), one with the bacteria Bacillus sp. BDCC-TUSA-3 and the other with R. erythropolis, were constructed, with polyurethane foams as an attachment support. They were optimized for surfactin production and biodesulfurization (BDS) of dibenzothiophene (DBT), respectively. Then, the two bioreactors were combined to form a two-stage VRICR where an appropriate fraction of Bacillus sp. reactor effluent, containing surfactin, was mixed with the influent fed into R. erythropolis bioreactor, containing DBT in hexadecane. The BDS rate and volumetric reactor productivity were greatly increased to 210.5 mM 2HBP.kg^?1.h^?1 and 16.6 mM 2HBP.L^?1.h^?1, respectively. Sulfur concentration decreased from 398 down to <5 ppm. Additionally, surfactin was produced at high concentration (4.8 g.L^?1) with a volumetric reactor productivity of 720 mg_surfactin·L^?1.h^?1, which represents an extra added-value product that could markedly decrease operating costs. This study presents a feasible technology for efficient removal of sulfur from sulfur-containing fossil fuels and the production of biosurfactant as well.     

Compact quadrifilar helix antenna

Modifications to the geometry at the centre of the helical section of a 1/2 turn half-wavelength quadrifilar antenna are shown to provide a large reduction in the axial length compared to a conventional volute. In addition this technique provides a simple method of tuning the resonant frequency of the structure.     

Factors Influencing the Thermal Stability and Lead Sorption Capacity of Hydroxyapatite Manufactured by Precipitation Method Using Industrial Calcium Hydroxide

In this study, the thermal stability of hydroxyapatite was investigated as a function of synthesis factors such as pH, aging time, and calcination temperature. Hydroxyapatite was prepared using calcium hydroxide and orthophosphoric acid and the effect of heat treatment on lead sorption were determined by the batch equilibrium technique. Although the thermal stability of powders was independent from the synthesized condition up to 800°C the material produced at neutral pH and aged during 24 h indicated the suitable stability even at 1000°C. Also, the powder synthesized at above condition completely removed lead compared to that for the other powders.     

Design and implementation of a blind adaptive equalizer using Frequency Domain Square Contour Algorithm

Square Contour Algorithm (SCA) is a relatively new blind equalization algorithm which reduces the dispersion between the output of the equalizer and a square contour. In this paper we develop Frequency Domain Square Contour Algorithm (FD-SCA) which is based on frequency domain implementation of block based SCA. Simulation results reveal that FD-SCA exhibits the same performance as that of existing time domain SCA with significantly low computational complexity. The performance of the FD-SCA in terms of convergence rate is further enhanced using normalization in frequency bins. The complete hardware architecture for the proposed FD-SCA based on ASM design flow along with implementation results is also presented.     

Application of prioritized aggregation operators in preference voting

This paper clarifies, how a preference aggregation problem can be solved using the prioritized aggregation operators (PAO), where, a given group of candidates should be aggregated based upon their satisfaction for a collection of ranked places. The comparison results show that the proposed method can accurate aggregate a preference ranking system with less computation and without the need to solve any mathematical model. Also, a metasearch application shows the usefulness of applying the PAO for a preference aggregation. © 2010 Wiley Periodicals, Inc.     

Effect of Various Electrolytes on the Phase Separation and Thermodynamic Properties of p-Tert-Alkylphenoxy Poly (Oxyethylene) Ether in the Absence/Presence of Drugs

Cloud point (CP) measurements of 4-(1,1,3,3-tetramethylbutyl) phenyl-polyethyleneglycol (Triton X-100 (TX-100)) were performed in aqueous solution in the presence of drug Amikacin sulfate (AS)/Neomycin sulfate (NS)/(AS/NS+ different inorganic salts). In aqueous solution, the CP values of TX-100 first decrease with increasing concentration and then increase with increasing surfactant concentration. The CP values of TX-100 solutions were found to increase with the increasing concentration of the AS/NS drug. The CP values of TX-100-AS/NS mixtures were also observed to decrease with the increase of the concentration of salt. Different thermodynamic parameters such as standard free energy (), standard enthalpy () as well as the standard entropy () change of phase separation were calculated and discussed in relation to molecular interactions.