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ASEAN Journal of Chemical Engineering

AJChE
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Published by Universitas Gadjah Mada

ISSN : 26555409 EISSN : 26555409 DOI : https://doi.org/10.22146/ajche.52004

Core Subject : Science, Engineering,

Biochemistry, Genetics & Molecular Biology Chemical Engineering, Chemistry & Bioengineering Chemistry

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

Arjuna Subject : Teknik Kimia (semua kategori) - Kimia Proses dan Teknologi

Articles 13 Documents

1 2

Search results for , issue "Vol 2, No 1 (2002)" : 13 Documents clear

Rotating Biological Contactor for Biological Treatment of Poultry Processing Plant Wastewater Using Saccharomyces Cerevisiae Dr. Gashem Najafpour; Punita Nook Naidu; Azlina Harun Kamaruddin
ASEAN Journal of Chemical Engineering Vol 2, No 1 (2002)
Publisher : Department of Chemical Engineering, Universitas Gadjah Mada

Biological treatment using attached growth on a rotating biological contactor(RBC) was implemented for wastewater from poultry industries, which containsa high level of organic compounds due to the slaughtering, rendering of bonesand fats, and plucking processes. The wastewater mostly consists of proteins,blood, fat and feathers. Nutrients available in the wastewater may enhance thegrowth of microorganisms, thus, it allows biological treatment to be usedeffectively. On the other hand, there are problems associated with biologicaltreatment processes such as nutrients promoting algae growth. The controlvariables for the attached growth in RBC were wastewater detention time, effectivesurface for attached growth, disc submerged level in the wastewater basin, shaftrotation for aeration, pH control and supplementary nutrients. The attachedgrowth resulted to high COD refPoval. The best treatment was obtained after 24hours with 29 % disc submergence level. The effective surface area for cellgrowth was 10.7 m2 using 60 discs mounted on a shaft. The microorganismused for the attached microbial growth was Saccharomyces cerevisiae. The shaftwas rotating at 11 rpm. The treatment was improved with the addition of 1 v/vof 0.1 molar sodium hydroxide solution to the wastewater for controlling pH. A91 % COD removal was obtained with RBC operating at optimum conditions,with a DO concentration of 3.98 mg/l.Key words: Rotating biological contactors, Aerobic treatment, Poultry processing wastewater,Saccharomyces cereuisiae,Attached growth.

Gas Holdup and Gas-Liquid Mass Transfer Investigations in an Oscillatory Flow in a Baffled Column Taslim Taslim; Mohd Sobri Takriff
ASEAN Journal of Chemical Engineering Vol 2, No 1 (2002)
Publisher : Department of Chemical Engineering, Universitas Gadjah Mada

Gas holdup and gas-liquid mass transfer were investigated in a vertical baffled column. Pure carbon dioxide (C02) was used as the dispersed phase and tap water was used as the continuous phase. Gas holdup and mass transfer rate of C02 were measured under semi-batch condition, while the liquid phase was measured in batch mode. Gas holdup was estimated as the volume fraction of the gas in the two-phase mixture in the column. Mass transfer was expressed in terms of the liquid-side volumetric mass transfer coefficient (kLa). The effects of oscillation frequency, oscillation amplitude and gas flow rate on gas holdup andmass transfer were also determined. The results showed that a significant increase in gas holdup and mass transfer could be achieved in an oscillatory baffled column compared to a bubble column. Gas holdup and mass transfer were correlated as a function of power density and superficial gas velocity. Keywords: gas holdup, mass transfer coefficient, power density, superficial gas velocity

Application 0f Draft Tube in the Reduction of Backmixing Rate in Oscillatory Flow in a Baffled Column Mohd Sobri Takriff; Zuhrina Masyitah
ASEAN Journal of Chemical Engineering Vol 2, No 1 (2002)
Publisher : Department of Chemical Engineering, Universitas Gadjah Mada

Oscillatory flow in a baffled tube/column is an efficient way to enhance mixing in a straight smooth column. However, liquid oscillation moving back and forth across the baffle causes backmixing which is a disadvantage when plug flow is desired. This paper presents results from a study conducted to reduce the backmixing rate in oscillatory flow in a baffled column with the use of a draft tube. Results of this study showed that backmixing increases with oscillation velocity and decreases with liquid flow rate. The use of a draft tube reduces backmixing. The backmixing reduction is proportional to the ratio of L/Do However, the draft tube can not be extended too long because it disrupts the flow behavior in the column and creates dead zones near the baffle region. The draft tube length is maximized by extending it to both sides of the baffle, provided that the L/De on each side of the baffle is at 0.67 or less.

Sensitivity Analysis of the Life-Cycle Inventories of Electricity and Hydrogen as Energy Vectors for the Philippine Automative Transport Sector Raymond R. Tan; Alvin B. Culaba
ASEAN Journal of Chemical Engineering Vol 2, No 1 (2002)
Publisher : Department of Chemical Engineering, Universitas Gadjah Mada

The Philippine automotive transport sector accounts for a significant portion ofthe country's petroleum consumption and air emissions. Research in alternative fuels for road vehicles is thus an essential element in the country's long-term-electrical environmental management strategy. Two radical vehicle technologies propulsion systems and fuel hydrogen for fuel cells - are widely considered to be the most promising energy vectors from an environmental standpoint. Electric vehicles (EV) and fuel cell vehicles (FCV) are driven by electric motors; the former use electricity stored in batteries, while the latter generate electricity from the oxidation of hydrogen. Potentially, both electric power and fuel hydrogen can be sustainably produced using renewable energy sources, and their use in vehicles generates almost no direct pollution. However, life-cycle assessment (LCA) may reveal significant environmental impacts from the infrastructure required to produce and distribute these energy vectors on a commercial scale. This study quantifies the life-cycle air emissions and energy balances associated with the use of electricity and hydrogen for motor vehicle propulsion in order to determine which fuel offers more environmental benefits. The assessment uses a modified version of the GREET 1.Sa fuel cycle inventory model, with corrections made to account for Philippine conditions. Sensitivity analysis is performed in the model to determine the effect of marginal power generation mix and system transmission losses on the life-cycle inventories of both energy vectors. The results of the simulation indicate that for a given marginal power generation mix, there is no clear-cut advantage in terms of environmental performance for either hydrogen or electricity.

An Improved Method to Calculate the Conservation of Mass in the Simulation of Rapid Pressurization Depressurization in a Packed Bed Thomas S.Y Chong; William R. Paterson; David M. Scott
ASEAN Journal of Chemical Engineering Vol 2, No 1 (2002)
Publisher : Department of Chemical Engineering, Universitas Gadjah Mada

The work described here forms part of a project to model rapid pressure swing adsorption (RPSA), which is a single-bed process used for air separation. We have earlier identified a form of model and boundary conditions for an axially dispersed plug flow model that conserves mass. We solve the RPSA models numerically by spatially discretizing the partial differential equations to a system of ordinary differential equations (ODEs), which are then integrated over time. Although the formulation of our models conserves mass, our numerical simulations, however, do not perfectly conserve mass because of discretization error and rounding error. The discrepancy in the conservation of mass is computed as a guide to the numerical accuracy of the calculations. The computation of the conservation error requires the evaluation of time integrals of molar flowrates in and out of the bed. Since the velocity at the feed end of the bed changes rapidly with time, the application of quadrature to evaluate the time integrals does not provide the accuracy required. In this paper, the inadequacy is demonstrated using a simple problem, i.e. pressurization and depressurization into a non-adsorptive bed. An improved method is proposed. By transforming equations involving time integrals into ODEs, excellent accuracy is obtained. Further, this transformation minimizes the number of decision parameters that need to be specified by the users of the computer programs. Keywords: rapid pressure swing adsorption, modelling and simulation, packed bed.

CO Oxidation over Metal Oxide CatalystSupported by Indonesian Natural Zeolite Suryo Purwono
ASEAN Journal of Chemical Engineering Vol 2, No 1 (2002)
Publisher : Department of Chemical Engineering, Universitas Gadjah Mada

The objectives of this study are to attempt to develop catalysts and to find the operating conditions under which combustible waste gases concentrations in the exhaust gases can be eventually reduced to satisfy air pollution standards. The results shows that using impregnation method, nickel and vanadium metals, as active components of the catalyst, can be dispersed on the natural zeolite as catalyst support. The reaction rate measurements of catalytic oxidation of CO was done in the temperature range between 300 and 550°C using a differential micro-reactor. The catalysts used for this experiment were vanadium pentoxide and nickel oxide on activated natural zeolite. To avoid fluidization, the reactant gases were flowed downward. The results show that the reaction rate depends strongly on the bed temperature and feed concentration and is not controlled by bulk phase mass transfer and pore diffusion.

Oscillatory Flow Mixer for Pulp Bleaching Taslim Taslim; Mohd Sabri Takriff
ASEAN Journal of Chemical Engineering Vol 2, No 1 (2002)
Publisher : Department of Chemical Engineering, Universitas Gadjah Mada

This paper reports the results of an investigation on the use of oscillatory baffled column as a mixer for pulp bleaching. Unbleached hardwood kraft pulp was bleached using hydrogen peroxide. Variables studied were oscillation frequency, oscillation amplitude, and pulp consistency. The mixing process was achieved by oscillating pulp suspension in a periodically baffled column at a certain frequency and amplitude. The mixing quality of pulp bleaching was quantified using mixing index. The results showed that mixing quality improved with oscillation frequency and amplitude, but decreased with pulp consistency. This typical device is very promising as a mixer for pulp bleaching.

Deagglomeration of High Purity Fine Alumina Powder via pH Control Andanastuti Muchtar; Norazmira Wati; Nor Azri Jaafar
ASEAN Journal of Chemical Engineering Vol 2, No 1 (2002)
Publisher : Department of Chemical Engineering, Universitas Gadjah Mada

This paper presents results from a study on the effect of the pH of suspensions on the deagglomeration of a high-purity (99.99%), fine-grained alumina powder. The pH of the suspension was varied between pH 2 and 3. It is the aim of the study to determine the best pH for a successful dispersion of the alumina powders in the suspension. A series of rheological studies and analytical work under Scanning Electron Microscopy were conducted. It was found that the best pH was pH 2. Data obtained from rheological studies using a viscometer showed that the alumina suspension prepared at pH 2 was least viscous, which may be taken as a negative indicator of the presence of agglomerates. This hypothesis is validated by visual inspection using SEM. For the pH 2 samples, a successful removal of the agglomerates in the green compact has encouraged the sinterability of the samples and thus, resulted in an earlier sintering process at a low-firing temperature. In addition, the sintering characteristics and microstructures of the samples prepared with a pH 2 suspension are also presented.

Reduction of NOx Emission from Gas TURBINE COMBUSTOR Applying Fuel-Staged Combustion Mohammad Nazri; Mohd. Jaafar
ASEAN Journal of Chemical Engineering Vol 2, No 1 (2002)
Publisher : Department of Chemical Engineering, Universitas Gadjah Mada

A two-stage lean/lean gas turbine combustor was developed with low NOx characteristics in each stage using a small radial swirler of 40-mm outlet diameter in the pilot stage. Both flame tubes were arranged in series with the smaller combustor (76 mm inside diameter) as the pilot stage and the larger combustor (140 mm inside diameter) as the main stage. The pilot stage was fuelled via vane passage fuel injector, while the main stage was fuelled around the wall of the exit plane of the pilot stage, using wall fuel injectors. Low NOx emissions were obtained when using fuel staging for methane fuel, as low as 6 ppm. A NO. reduction of more than 40 % was obtained at equivalence ratio of near 0.7, when using fuel staging compared to the non-fuel-staging test. Tests were conducted using methane as fuel. This was achieved at very small increase in carbon monoxide emissions especially near the rich region and with almost no increase at all in the unburned hydrocarbon emissions at the same equivalence ratio.Keywords: NOx emissions, fuel staging, carbon monoxide, swirler.

Effects of Shear Rate on Morphology and Gas Separation Performance as Asymetric Polysulfone Membranes Ahmad Fauzi Ismail; Lai Ping Yean
ASEAN Journal of Chemical Engineering Vol 2, No 1 (2002)
Publisher : Department of Chemical Engineering, Universitas Gadjah Mada

Asymmetric polysulfone flat sheet membranes have been produced by a dry/wet casting technique. The membranes were produced at different shear rate. Gas permeation properties were examined using pure hydrogen and nitrogen as test gases. Infrared dichroism was detected in all samples, the extent being greater in the high shear membranes. This suggests that the polymer molecules become aligned under high shear. Gas separation tests showed that the higher shear membranes exhibited greater selectivity (H!Nz)' Some of the membrane selectivities even surpass the intrinsic selectivity of the membrane polymer. Increasing shear rate during casting had decreased skin layer thickness and thus increased pressure-normalized flux. High-shear casting also enhances the molecular orientation in skin layer and, in turn, heighten selectivity of membrane. Therefore, correlation of rheological aspects with primary phase inversion parameters provides a potential platform to develop high performance asymmetric polysulfone membranes for gas separation.Key words: asymmetric membranes, gas separation, rheology, molecular orientation, super-selective, polysulfone

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Ari Pramudyantoro

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ajche.ft@ugm.ac.id

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+62274555320

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Jln. Grafika No. 2 Kampus UGM Yogyakarta Indonesia 55281

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Home Page

OAI Link

Editorial Team

Contact

Reviewer

Google Scholar

Contact Name Ari Pramudyantoro

Contact Email ajche.ft@ugm.ac.id

Phone +62274555320

Journal Mail Official ajche.ft@ugm.ac.id

Editorial Address Jln. Grafika No. 2 Kampus UGM Yogyakarta Indonesia 55281

Location Kab. sleman, Daerah istimewa yogyakarta INDONESIA

Abstract

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Abstract

Abstract

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Abstract

Contact Name
Ari Pramudyantoro

Contact Email
ajche.ft@ugm.ac.id

Phone
+62274555320

Journal Mail Official
ajche.ft@ugm.ac.id

Editorial Address
Jln. Grafika No. 2 Kampus UGM Yogyakarta Indonesia 55281

Location
Kab. sleman,

Daerah istimewa yogyakarta

INDONESIA