ASEAN Journal of Chemical Engineering
The ASEAN Journal of Chemical Engineering publishes papers on Chemical Engineering, specifically but not limited to the areas of thermodynamics, reaction kinetics, transport phenomena, process control, environment, energy, biotechnology, corrosion, separation science, powder technology, materials science, and chemical engineering education
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<![CDATA[Comparison of Steady State and Dynamic Interaction Measurements in Multiloop Control Systems ]]>
<![CDATA[Renanto Handogo]]>;
<![CDATA[Avon T. H.]]>;
<![CDATA[Joko Lelono]]>
<![CDATA[ ASEAN Journal of Chemical Engineering Vol 5, No 1 (2005) ]]>
Publisher : <![CDATA[Department of Chemical Engineering, Universitas Gadjah Mada ]]>
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DOI: 10.22146/ajche.50158
<![CDATA[The applicability of the steady-state Relative Gain Array (RGA) to measure dynamic process interactions in a multiloop control system was investigated. Several transfer function matrices were chosen, and the gains, time constants, and dead times of their elements were varied to represent the systems with dominant dynamic interactions. It was shown that the steady-state RGA method predicted the controller pairing accurately if the pairing elements recommended by RGA had the bigger gains and the same or smaller time constants compared to other elements in the corresponding rows. When these conditions were not met, the RGA would give a wrong result, and dynamic interaction measurements, such as the Average Dynamic Gain Array (ADGA) and the Inverse Nyquist Array (lNA), should be used instead to determine the best controller pairing in a multiloop control system. Keywords: Control pairing, dynamic process interaction, multiloop control systems, Relative Gain Array (RGA), and steady state.]]>
<![CDATA[Simulation of Ethyl Tert-Butyl Ether Production from Tert-Butyl Alcohol and Ethanol in Reactive Distillation ]]>
<![CDATA[Suttichai Assabumrungrat]]>;
<![CDATA[Varong Pavarajarn]]>;
<![CDATA[Darin Wongwattanasate]]>;
<![CDATA[Piyasan Praserthdam]]>
<![CDATA[ ASEAN Journal of Chemical Engineering Vol 5, No 1 (2005) ]]>
Publisher : <![CDATA[Department of Chemical Engineering, Universitas Gadjah Mada ]]>
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DOI: 10.22146/ajche.50159
<![CDATA[Reactive distillation was applied for the synthesis of ethyl tert-butyl ether (ETBE) from a liquid-phase reaction between tert-butyl alcohol (TBA) and ethanol (EtOH) catalyzed by commercial ~-zeolite catalyst with Si/AI ratio of 55. The major side reaction of this system was the dehydration of TBA to isobutene (lB). From the present researchers' previous work, it was found that B-zeolite was superior to commercial Amberlyst-15 catalyst in reaction selectivity. The kinetic parameters for the reactions, which were determined using a semibatch reactor operated at various temperatures, were used for simulation in Aspen Plus TN program. Various operating parameters, such as heat duty, molar ratio of Hz0: EtOH, and refluxratio, were investigatedfor their effectson reactive distillation performance. Keywords: ,B-zeolite,ethyl tert-butyl ether (ETBE) synthesis, and reactive distillation.]]>
<![CDATA[Synthesis of Robust Water Reuse Networks Using Fuzzy Nonlinear Programming:Mass Exchange-Based Processes ]]>
<![CDATA[Raymond Girard R. Tan]]>;
<![CDATA[Dennis E. Cruz]]>
<![CDATA[ ASEAN Journal of Chemical Engineering Vol 5, No 1 (2005) ]]>
Publisher : <![CDATA[Department of Chemical Engineering, Universitas Gadjah Mada ]]>
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DOI: 10.22146/ajche.50160
<![CDATA[Water consumption and effluent generation in industrial plants can be effectively reduced by maximizing utilization of partially contaminated water. A dual approach consisting of graphical pinch methods for targeting followed by the synthesis of water reuse networks using such techniques as mathematical programming is usually employed. Reliable process data is necessary for successful plant retrofitting. In most cases, however, the necessary limiting concentrations and mass loads must be deduced from limited information. It thus becomes necessary to balance the conflicting objectives of minimizing water usage and of ensuring that sufficient stream concentrations fall within their limiting values. The use of fuzzy nonlinear programming for the synthesis of robust water reuse networks is demonstrated using a four-process case study from the literature. Keywords: Fuzzy nonlinear programming, process integration, and water reuse network (WRN).]]>
<![CDATA[Water Plasma Generation Under Atmospheric Pressure for Waste Treatment ]]>
<![CDATA[Takayuki Watanabe]]>
<![CDATA[ ASEAN Journal of Chemical Engineering Vol 5, No 1 (2005) ]]>
Publisher : <![CDATA[Department of Chemical Engineering, Universitas Gadjah Mada ]]>
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DOI: 10.22146/ajche.50161
<![CDATA[DC lOO%-steam plasma characteristics were investigated for the application of halogenated hydrocarbon decomposition because steam plasmas are chemically reactive. However, plasma system generally requires complex subsystems such as steam generators and cooling units. The presented steam plasma system is a portable light-weight plasma generation system that does not require any gas supply unit. The system has high-energy efficiency because it does not need additional cooling water. Electrodes of high durability are required for a DC lOO%-steam plasma because the electrodes are exposed to reactive conditions. Thus, the electrode's characteristics were also investigated under different configurations and conditions. Keywords: CFC decomposition, halon decomposition, steam plasma, thermal plasma, and waste treatment.]]>
<![CDATA[Hydrogen Production from Synthesis Gas Using the Photosynthetic Bacterium Rhodospirillum rubrum ]]>
<![CDATA[Ghasem Najafpour]]>;
<![CDATA[Habibollah Younesi]]>
<![CDATA[ ASEAN Journal of Chemical Engineering Vol 5, No 1 (2005) ]]>
Publisher : <![CDATA[Department of Chemical Engineering, Universitas Gadjah Mada ]]>
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DOI: 10.22146/ajche.50162
<![CDATA[Production of biological hydrogen by anaerobic photosynthetic bacteria, specifically Rhodospirillum rubrum, from synthesis gas was successfully conducted at ambient temperature and pressure. The influence of initial acetate concentration as the substrate for microbial growth was investigated in a batch system. Series of experiments were conducted using serum bottles as bioreactor. The agitation rate and light intensity were adjusted at 200 rpm and 1,000 lux, respectively. The concentration of acetate as carbon source was varied from 0.5 to 3.0 g/I. It was observed that the increase in concentration of the carbon source from 2.5 to 3 g/l resulted in the decrease both in the growth of the microorganism and in hydrogen production rate. Experimental results showed that the optimum acetate concentration would be from 1 to 2 g/I. The resulting data also showed that in 1-2 g/I acetate, highest hydrogen formation and cell concentration were obtained. Additional acetate in the initial culture medium inhibited the growth of R. rubrum. An inverse relationship between acetate concentration and initial cell growth was observed. This article presents a method to calculate the mass transfer coefficient for gaseous substrates and the process parameters involved in a gas and liquid fermentation system. The procedure had been defined by experimental data for the bioconversion of CO to C02' while H20 is converted into hydrogen. Hence, a biologically-based water-gas shift reaction provided an attractive alternative improvement for renewable resources to achieve higher hydrogen production. Keywords: Anaerobic bacteria, batch culture, coefficient, CO uptake rate, mass transfer, photobiological hydrogen, and Rhodospirillum rubrum.]]>
<![CDATA[Kinetic Parameters Determination of Benzene Vapor Adsorption on Activated Carbon Using Differential Permeation Technique ]]>
<![CDATA[Aswati Mindaryani]]>;
<![CDATA[Boma W. Tyoso]]>;
<![CDATA[Wahyudi B. Sediawan]]>;
<![CDATA[Supranto Supranto]]>
<![CDATA[ ASEAN Journal of Chemical Engineering Vol 5, No 1 (2005) ]]>
Publisher : <![CDATA[Department of Chemical Engineering, Universitas Gadjah Mada ]]>
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DOI: 10.22146/ajche.50163
<![CDATA[Equilibrium and kinetic data are very important for a reliable design of a large-scale adsorption system. The objective of the research was to determine the particle scale kinetic parameters of strongly adsorbed volatile organic compounds (VOCS)in activated carbon (AC) by using the differential permeation technique. The experimental rig consisted basically of upstream and downstream reservoirs separated by a slab-shaped AC that is 2 mm thick. After cleaning the slab overnight at 400 K and under vacuum condition, the experiment was started by opening the valve to allow vapor to diffuse through the AC. The upstream and downstream pressures were continuously recorded until equilibrium was reached. Another experiment was run by increasing incrementally the upstream pressure. The same experiment was carried out using nonadsorbed gas (argon) to estimate both Knudsen permeability and viscous permeability. The Knudsen, viscous, and surface diffusivities were determined by matching the total permeability against the experimental data. From the data obtained, it was found that both porosity and surface diffusivity change with loading. The surface diffusivity of benzene vapor in AC pores does not follow the Darken model, but it follows the hydrodynamic model of Gilliland, especially when the porosity is relatively constant at high loading. Keywords: Adsorption, benzene, differential permeation, kinetic, and volatile organic compounds (VOCs).]]>
<![CDATA[Removal of Dyes by Aqueous Mixed Coagulants ]]>
<![CDATA[Peik Yin Ooi]]>;
<![CDATA[Tjoon Tow Teng]]>;
<![CDATA[A. K. Mohd Omar]]>;
<![CDATA[N. A. R. Nik Norulaini]]>
<![CDATA[ ASEAN Journal of Chemical Engineering Vol 5, No 1 (2005) ]]>
Publisher : <![CDATA[Department of Chemical Engineering, Universitas Gadjah Mada ]]>
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DOI: 10.22146/ajche.50164
<![CDATA[Alum, MgCl2, and mixtures of alum and MgCl2 have been used as coagulant to remove coloring matter in the reactive dye Levafix Brill Blue EBRA. The jar test was used to determine the effectiveness and the optimal condition of the coagulation process in terms of pH of the coagulation process, coagulant dosage, percentage color removal, and floc settling time. Coagulant dosages of 1,000-5,000 ppm were studied. The treatment of textile industry wastewater was done in the treatment plant of a printing mill. The results showed that coagulation by MgCl2 and alum occurs at the removal pH ranges of 10.5-11.0 for MgCl2 and 4.0-6.0 for alum. The mixtures of MgCl2 and alum gave two distinct effective color-removal zones at pH 4-5.5 and pH 8-9.5. The addition of alum to MgCl2 shifted the optimal pH of MgCl2 from 10.5-11. 0 to 8. 0-9.5. The alum dose of 1,000-3,000 ppm in the coagulant mixture increased by 10-25 % the color removal in the alkaline zone. Floc settling time was found to (a) increase with coagulant dose and (b) take longer in the acidic color-removal zone than in the alkaline zone. The presence of alum increased the floc settling time in the alkaline zone. The study done at the treatment plant of a printing mill showed similar results. A mixture of 60% MgClz and 40% alum at an average dosage of 2,800 ppm gave a color removal of 97% and reductions of 88% for COD and 69% for suspended solids. Keywords: Chemical coagulation, color reduction, mixed coagulants, and textile waste.]]>
<![CDATA[Mathematical Model for the Prediction of Gas-Liquid Mass Transfer in Airlift Contactors ]]>
<![CDATA[P. Pavasant]]>;
<![CDATA[P. Wongsuchoto]]>;
<![CDATA[V. Suksoir]]>
<![CDATA[ ASEAN Journal of Chemical Engineering Vol 5, No 1 (2005) ]]>
Publisher : <![CDATA[Department of Chemical Engineering, Universitas Gadjah Mada ]]>
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DOI: 10.22146/ajche.50165
<![CDATA[A mathematical model was proposed to explain the gas-liquid mass transfer behavior in an airlift contactor (ALC). The model separated the airlift contactor into three sections: riser, gas separator, and downcomer. The riser and downcomer were described using the dispersion model whilst the gas separator was modeled as a .completely mixed tank. All parameters needed for the model were obtained from independent experiments both carried out in this work and reported elsewhere. Simulation results were compared with a number of experimental data obtained from the systems with various geometrical and operational conditions. It was shown that the model could predict the oxygen mass transfer between phases in the ALC with reasonable accuracy. Keywords: Airlift contactor (ALC), dispersion model, mass transfer, mathematical model, and verification.]]>
<![CDATA[Enhancemen Effect of Hydrogen Sulfide Over Metal Ion-Exchange Mesoporous Silicate FSM-16 for Acid Catalyzed Reactions. ]]>
<![CDATA[Lebong Andalaluna]]>;
<![CDATA[Masatoshi Sugioka]]>
<![CDATA[ ASEAN Journal of Chemical Engineering Vol 5, No 1 (2005) ]]>
Publisher : <![CDATA[Department of Chemical Engineering, Universitas Gadjah Mada ]]>
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DOI: 10.22146/ajche.50166
<![CDATA[The activity enhancement of metal ion-exchange mesoporous silicate FSM-16 (MeFSM-16) by sulfiding with hydrogen sulfide was studied using acid-catalyzed reactions, isomerization of I-butene, cis-2-butene and cyclopropane, as model reactions. It was revealed that the catalytic activities of MeFSM-16 for the acid-catalyzed reactions were remarkably enhanced after sulfiding with hydrogen sulfide. Moreover, it was observed that the optimum enhancement effect of hydrogen sulfide was obtained at the sulfiding temperature of 200°C. Infrared spectroscopic measurement of pyridine adsorption over sulfided MeFSM-16 showed that the activity enhancement of MeFSM-16 resulted in the generation of new Bronsted acid sites. Keywords: Metal ion-exchange, mesoporous silicate, hydrogen sulfide, and activity enhancement.]]>
<![CDATA[Application of Evidence Theory to Automate The Process of Removing Toxic Chromium Ions in Wastewater ]]>
<![CDATA[Mohd Marzuki Mustafa]]>;
<![CDATA[Siti Rozaimah Sheikh Abdullah]]>;
<![CDATA[Rakmi Abdul Rahman]]>
<![CDATA[ ASEAN Journal of Chemical Engineering Vol 5, No 1 (2005) ]]>
Publisher : <![CDATA[Department of Chemical Engineering, Universitas Gadjah Mada ]]>
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DOI: 10.22146/ajche.50167
<![CDATA[A new method to automate the batch process of removing toxic chromium ions from wastewater using Oempster-Shafer's (OS) evidence theory is described. The removal of the toxic chromium ions from wastewater is a good example of a process where conventional output or state feedback controllers cannot be simply applied because the concentration of the ion cannot be easily measured online or estimated from other measured parameters. The batch process of removing toxic chromium ions by adding a reducing agent involves reduction and oxidation (redox) reactions which are usually monitored using the oxidation reduction potential (ORP) probe. However, the relationship between ORP and concentration of chromium ions is difficult to establish, hence, a reliable online control is seldom achieved using output feedback control. The approach here is to treat the sequence of ORP values obtained at each sample interval as partial evidences with different degrees of belief to indicate whether the removal process has been completed or not. Using OS's theory of evidence these partial evidences are fused or aggregated to give a more reliable and robust real time control decision. In this paper, a modification is proposed to overcome deficiencies in the OS's combination rule in combining sequences of evidence from the same source. The algorithm based on this evidence theory has been tested in the laboratory, and the results obtained show that the algorithm is robust with respect to noise and process variation.Keywords: Chromium removal process, Dempster-Shafer's evidence theory, evidence aggregation, information fusion, and oxygen reduction potential (CRP).]]>
