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Abstract : Investigation on the Thermal Stability of Refined Palm Oil Produced from Membrane-Based Refining Technique
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Abstract: The main objective of this work is to study the heat stability of refined palm oil produced from membrane-based refining process. Two novel routes of refining process have been proposed in which the first one was to integrate conventional refining process with ultrafiltration (UF) membrane technology while the second route was based on the integration between conventional refining process and UF membrane-solvent extraction process. The results revealed that the two novel refining routes showed improvement on free fatty acid (FFA) stability compared with the conventional technique throughout 5-day studied period. With respect to peroxide value (PV), it is found that only the first proposed route showed very similar increasing trend with the conventional refining process. In addition to this, it is also found that the two refining routes which were operated at 260oC showed slightly better colour stability in comparison to conventionally-produced oil. Keywords: Membrane technology, solvent extraction, crude palm oil, free fatty acid, phospholipids.Download Full Article |
Abstract : Detailed Potentiometric Study of Al3+ and Cr3+ with Malic Acid in Aqueous Solutions
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Abstract: It appeared that malic acid solubilized both Al3+ and Cr3+ in aqueous solutions at all pH-values in 0.1 M NaNO3 at 25 oC. The detailed potentiometric measurements indicated that these free tri-valent metal ions released a net of three protons (3H+’s) into the solution. Free malic acid released a net of (2H+’s) into the solution from the two carboxylates. However, in the presence of metal ions malic acid effectively releases a net of three protons (3H+’s) into the solution; two from the two carboxylates and the third from the alcoholic group. The reaction mixture of Al3+:malic acid indicated the formation of a dimeric species. The proposed structure of this dimeric species is in good agreement with what has been shown in the literature. We are presenting a dimeric species that may play an important role in malate transportation across cell membrane. Formation of the Al3+-malic acid complexes cover the span of a total of 400 mV; from +250 mV to -150 mV. The Cr3+-malic acid reaction mixture indicated the formation of a dimeric species as well. Keywords: Aqueous solutions, Dimeric species, Malic acid, Al3+, Cr3+, and Speciation diagrams.Download Full Article |
Abstract : Physical and Gas Transport Properties of Asymmetric Hyperbranched Polyimide-Silica Hybrid Membranes
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Abstract: Physical and gas transport properties of the asymmetric hyperbranched polyimide (HBPI) -silica hybrid membranesprepared with a dianhydride, 4,4’-(hexafluoroisopropylidene)diphthalic anhydride (6FDA), and an asymmetric triamine, 2,4,4’-(triaminodiphenyl)ether (TADE), were investigated and compared with those of the symmetric HBPI-silica hybrid membranes prepared with a symmetric triamine, 1,3,5-tris(4-aminophenoxy)benzene (TAPOB). The HBPI-silica hybrid membranes were prepared via sol-gel reaction using hyperbranched polyamic acid of which end groups were modified with silane coupling agents, water and tetramethoxysilane. The thermal mechanical and dynamic mechanical analysis measurements confirmed that the rigidity of asymmetric HBPI was higher than that of symmetric HBPI because of the rigid and asymmetric structure of TADE monomer. In addition, the degree of branching of asymmetric HBPI is lower than that of symmetric HBPI because of the different reactivity of the three amino groups included in TADE. The rigidity and linearity of HBPIs had an effect on the progression of sol-gel reaction, consequently the gas transport properties. The increasing of the gas permeability coefficient of the asymmetric dianhydride(DA)-HBPI-silica hybrid membranes with increasing silica content was smaller than those of symmetric DA- and amine(AM)-HBPI-silica hybrid membranes. In addition, the gas permeability coefficient of the asymmetric AM-HBPI-silica hybrid membranes decreased with increasing silica content. This was due to the fact that the dispersibility of silica in the asymmetric HBPI-silica hybrids, of which polymer chain was more rigid and linear than those of symmetric HBPI-silica hybrid, was not as fine as in the symmetric HBPI-silica hybrids, and that the long and tortuous diffusion path was newly formed by hybridization with silica. Keywords: Hyperbranched Polyimide, Silica hybrid, Gas permeability, Asymmetric, Symmetric.Download Full Article |
Abstract : Neural Network Model Identification and Advanced Control of a Membrane Biological Reactor
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Abstract: System identification with different input-output structures, for a membrane biological reactor (MBR), was performed using artificial neural networks (ANN) black-box modeling. The ANN models were able to capture the dynamic flux experimental literature data. Sensitivity analyses were applied on the ANN models to quantify the effects of variation in the process inputs (backwash pressure, vacuum pressure, backwash and vacuum time) on the process output (flux rate. Sensitivity analysis was applied on the developed NN in order to find the optimum backwash scheduling. The maximum flux was attained at around 165 (L/m2·day) that corresponded to an optimum vacuum-to-backwash time ratio of 10 minutes vacuum to 2 minutes backwash. Advanced control strategy using neuro-model predictive control (NN-MPC) methodology was applied to control the MBR system. The NN-MPC parameters were tuned to attain an optimum performance. The NN-MPC was efficient in tracking the flux set-point changes by adjusting vacuum-to-backwash time ratio within the operation constraints. Keywords: Backwash, flux, optimization, sensitivity analysis, fouling control, wastewater treatment, neuro-model predictive control.Download Full Article |
