International Journal of Engineering
Volume:25 Issue: 4, Nov 2012

The integration of batch fermentation and membrane-based pervaporation process in a membrane bioreactor (MBR) was studied to enhance bioethanol production compared to conventional batch fermentation operated at optimum condition. For this purpose, a laboratory-scale MBR system was designed and fabricated. Dense hydrophobic Polydimethylsiloxane (PDMS) membrane was used for pervaporation. For fermentation, pure stock culture of Saccharomyces cerevisiae as microorganism and glucose as substrate were used. Compared to conventional batch fermentation, the MBR resulted in increase of cell density, decreasing ethanol inhibition, improved productivity and yield, and resumption of clean and concentrated ethanol. These effects can be attributed to the presence of membrane as a selective separation barrier for removal of ethanol from fermentation broth. The ethanol productivity increased at least by 26.83% over conventional batch fermentation; while concentrated ethanol was obtained in the condensate of cold-trap. Furthermore, ethanol concentration in permeated side was approximately 6 to 7 times higher than that of the broth. Some biological kinetic models were investigated for determination of growth rate kinetics in conventional and MBR batch fermentation. The best results were obtained using the Monod kinetic model.

In this study, the adsorption behavior of anionic dyes from aqueous solution onto mesoporous carbon material (CMK-1) and modified with polymer (PANI/CMK-1) has been investigated as a function of parameters such as adsorbent dose (0.08-0.8 g/L), solution pH 3–10, contact time and initial concentration (10-100 mg/L). The influence of these parameters on the adsorption capacity has been studied using the batch process. The experimental data were analyzed by the Langmuir and Freundlich isotherms. The adsorption isotherm was found to follow the Freundlich model.The structural order and textural properties of the synthesized materials were studied by XRD, SEM, and nitrogen adsorption–desorption analysis. The characteristic results indicated that the modification was successfully done. This study showed that modified nanoporous carbon materials are excellent adsorbents for the removal of anionic dyes from wastewater.

This study investigated the feasibility of Date-palm) Phoenix dactylifera (Leaf Ash (DLA) (an inexpensive agricultural-byproduct) as an application to adsorb Pb(II) ions. An adsorption process was carried out to evaluate initial concentration Pb(II) ions, adsorbent dose, contact time, pH and temperature on the systematic removal of Pb(II). The effects were examined and results showed that removal efficiency decreased with an increase of initial Pb(II) concentration and optimum removal efficiency of 99.72% was at 50 mg/l Pb(II) solution, 0.5 g/l DLA dose and pH level of 5. The results showed that with increased dose of adsorbent dose, Pb(II) adsorption also increased. The equilibrium data were analyzed using the Langmuir and Freundlich isotherm models by nonlinear regression analysis at 20, 30 and 40 ˚C. It was found that the Langmuir isotherm model fitted better than the Freundlich isotherm model. However, the kinetic adsorption of Pb(II) ions was tried using three kinetic models, the pseudo-first-order, the pseudo-second-order and the intra-particle diffusion model and these tests demonstrated that the overall adsorption process was the one most suited to the pseudo-second-order kinetic model. Thermodynamic parameters, Gibbs free energy (∆G˚), enthalpy (∆H˚), and entropy (∆S˚) were also evaluated, with application of the van’t Hoff equation that describes the dependence of equilibrium constant on temperature. Final evaluation of the thermodynamics of Pb(II) adsorption onto DLA demonstrated that adsorption was spontaneous and endothermic.

Researches show that the strength criterion is inadequate for design of structures against seismic loads. Since structures yield and experience plastic deformation under strong ground motion, considering structural damage with inelastic behavior may be a considerable criterion for design and control of the structures.In this paper, three steel structures with dual system consisting of intermediate moment resisting frames and concentrically braced ones were selected and designed based on ASD method of UBC-97. Then, for evaluating inelastic behavior, these structures were subjected to three earthquake records and the nonlinear dynamic analyses were done by the PERFORM 3D (VER 4.0.1) software. Next, hysteretic energy and damage measure were computed for all members of the structures in all stories. Finally, it has been tried to find a method for reducing the damage of structural elements and making the damage distribution uniform among structural members of each story.

Structural concrete exposed to marine environment deserves special attention as the diffused sea salts chemically react with harden cement matrix and forms various expansive/leachable compounds leading to loss of material, strength, cracking, spalling etc. This study cover the effect of sea water on the specimens cast from two grades of concrete exposed to simulated marine environment over a year. Enhanced salt concentration i.e. 1N, 3N, 6N, 12N of the curing solution was used to get the accelerated effect. Several destructive and non destructive tests including XRD study were performed to assess the state of deterioration. From test results, it is observed that concrete exposed to sea water of different concentration suffers a loss of compression strength of around 19% and 33% respectively as compared to 28 days and 365 days of plain water cured concrete.

The effect of organic phenol on the compressive and flexural strength of a metakaolin based geopolymer is studied. It was found that 12 wt% phenol resins can increase the compressive and flexural strength by 30% and 65% respectively. In addition, the reinforcing effect of phenol resin is higher in Na-PS and Na-PSS type geopolymers rather than Na-PSDS. Two distinct endothermic peaks were detected in DTA curve which can be attributed to the release of water from phenol resin and its final thermal decomposition.

carbon nanotube Nanocomposite (HA-CNT) coatings were deposited via electrophoretic deposition (EPD). Hydroxyapatite was synthesized via microwave combustion method using calcium nitrate and glycing as starting materials. X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) revealed that pure hydroxyapatite nanoparticles have been synthesized. AISI 316L stainless steel and ethanol were used as substrate and dispersing medium, respectively. 5%wt carbon nanotube (CNT) was used as reinforcing phase. Uniform and macrocrack-free coatings were obtained both for HA and HA-5%wt CNT coatings. Scanning electron microscopy (SEM) showed that most of microcracks in HA coating has eliminated after introducing CNT as reinforcing phase. The variation of deposit weight by time and voltage is measured both for HA and HA-5%wt CNT coatings. Thickness measurements indicated that for both coatings, the thickness increases with deposition voltage. X-ray diffraction patterns indicated that HA has not decomposed after sintering at 850 ˚C for 2 hr in argon atmosphere.

The influence of the martensitic, martensitic+austenitic and austenitic structures in bending training on two-way shape memory effect (TWSME) in Ni-50.8 at %Ti and Ni-49.9 at %Ti alloys was studied. In addition of the primary structure, the effect of pre-strain, plastic strain, training cycle and training temperature on the TWSME was investigated. The prepared samples were trained in martensitic, martensitic+austenitic and austenitic states with bending deformation. The experimental results indicated that in martensitic state, the TWSME was obtained more than in the others. Also it was shown that the optimum pre-strain and number of training cycles in martensitic state than the other states are more and less, respectively. In addition it was shown that with increasing the training temperature in austenitic state, TWSME decreases.

In the current research project, sol-gel electrophoresis technique was utilized to grow titanium dioxide (TiO2) nanotubes. A titanium sol was prepared using organometallic precursors of titanium to fill the template channels. The prepared solwas driven into nanopores of porous anodic aluminum oxide templates under the influence of a DC electric field to form nanotubes on the pore walls. Tube formation was occured after chemical etching of the template pores with phosphoric acid. The simultaneous thermal analysis (STA) of the titanium gel determined the onset temperature for the anatase TiO2 crystallization. After the firing step, the phase structure of the produced nanotubes was evaluated based on the X-ray diffraction (XRD) investigations. Scanning electron microscopy and energy dispersive X-ray (SEM and EDX) studies showed that TiO2 nanotubes with uniform size and shape have been electrophoretically grown in the aluminum oxide template channels.