Widya Mandala Surabaya Catholic University

Surabaya, Indonesia

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Susanti C.E.,Widya Mandala Surabaya Catholic University
Advanced Science Letters | Year: 2017

CBR model is an approach to problem-based learning solution in a case study. CBR Model learners hone not only to identify problems but to know and understand the main source is the cause for the emergence of these problems so as to provide appropriate solutions as the strategic decisions and actions. This ability is important to have the students remember the students prepared by educational institutions in order to become a superior human being. © 2017 American Scientific Publishers All rights reserved.

Ahmed I.N.,National Taiwan University of Science and Technology | Nguyen P.L.T.,National Taiwan University of Science and Technology | Huynh L.H.,Can Tho University | Ismadji S.,Widya Mandala Surabaya Catholic University | Ju Y.-H.,National Taiwan University of Science and Technology
Bioresource Technology | Year: 2013

Bioethanol production from the shedding bark of Melaleuca leucadendron (Paper-bark Tree, PBT) was studied using subcritical water (SCW) pretreatment at various severities (So). High ethanol production was attained by implementing a factorial design on three parameters (So, solid loading and enzyme loading) in simultaneous saccharification and fermentation (SSF) mode. Ethanol concentration of 63.2gL-1 corresponding to ethanol yield of 80.9% were achieved from pretreated biomass (So=2.37) at 0.25gmL-1 solid and 16FPUg-1 glucan enzyme loadings. Similarly at 0.15gmL-1 solid loadings both high ethanol concentration (43.7gL-1) and high ethanol yield (91.25%) were achieved. Regression analysis of experimental results shows that all process parameters had significant role on maximum ethanol production, glucose solubility, ethanol yield and ethanol volumetric productivity. SSF of SCW treated PBT biomass is economically feasible for production of bioethanol. © 2013 Elsevier Ltd.

Soetaredjo F.E.,Widya Mandala Surabaya Catholic University | Ayucitra A.,Widya Mandala Surabaya Catholic University | Ismadji S.,Widya Mandala Surabaya Catholic University | Maukar A.L.,Widya Mandala Surabaya Catholic University
Applied Clay Science | Year: 2011

A potential application of KOH/bentonite as a catalyst for biodiesel production was studied. A series of KOH/bentonite catalysts was prepared by impregnation of bentonite from Pacitan with potassium hydroxide. The ratios between KOH and bentonite were 1:20, 1:10, 1:5, 1:4, 1:3, and 1:2. The characterization of KOH/bentonite and natural bentonite was conducted by nitrogen adsorption and XRD analysis. The effects of various reaction variables on the yield of biodiesel were investigated. The highest yield of biodiesel over KOH/bentonite catalyst was 90.70 ± 2.47%. It was obtained at KOH/bentonite 1:4, reaction time of 3. h, 3% catalyst, methanol to oil ratio of 6, and the reaction temperature at 60 °C. © 2010 Elsevier B.V.

Ismanto A.E.,Widya Mandala Surabaya Catholic University | Wang S.,Widya Mandala Surabaya Catholic University | Soetaredjo F.E.,Widya Mandala Surabaya Catholic University | Ismadji S.,Widya Mandala Surabaya Catholic University
Bioresource Technology | Year: 2010

Cassava peel was used as the precursor for activated carbon-based electrodes which were then prepared by a combination of chemical and physical activation. The surface of the activated carbon was treated with the oxidative chemical agents, 98 wt.% H 2SO 4, 65 wt.% HNO 3, and 30 wt.% H 2O 2 solutions. The surface modification had no significant effect on the specific surface area, but greatly influenced the surface chemistry of the carbons. The presence of oxygen-containing groups increased the polarity and hydrophilicity of activated carbon, and thus improved the performance of the activated carbon-based electrode. As a result, the specific capacitance of the HNO 3 modified AC-electrode reached 264.08 F/g, an increase of 72.6% compared to the original one. The results indicate that cassava peel waste can potentially be applied as a raw material for the production of low cost-high performance activated carbon electrode materials for Electric Double Layer Capacitors (EDLCs). © 2010 Elsevier Ltd. All rights reserved.

Suryaputra W.,Widya Mandala Surabaya Catholic University | Winata I.,Widya Mandala Surabaya Catholic University | Indraswati N.,Widya Mandala Surabaya Catholic University | Ismadji S.,Widya Mandala Surabaya Catholic University
Renewable Energy | Year: 2013

The waste Capiz shell was utilized as raw material for catalyst production for biodiesel preparation. During calcination process, the calcium carbonate content in the waste capiz shell was converted to CaO. This calcium oxide was used as catalyst for transesterification reaction between palm oil and methanol to produce biodiesel. The biodiesel preparation was conducted under the following conditions: the mole ration between methanol and palm oil was 8:1, stirring speed was 700 rpm, and reaction temperature was 60 °C for 4, 5, and 6 h reaction time. The amount of catalyst was varied at 1, 2, 3, 4, and 5 wt %. The maximum yield of biodiesel was 93 ± 2.2%, obtained at 6 h of reaction time and 3 wt % of amount of catalyst. In order to examine the reusability of catalyst developed from waste of capiz (Amusium cristatum) shell, three transesterification reaction cycles were also performed. © 2012 Elsevier Ltd.

Prahas D.,National Taiwan University of Science and Technology | Liu J.C.,National Taiwan University of Science and Technology | Ismadji S.,Widya Mandala Surabaya Catholic University | Wang M.-J.,National Taiwan University of Science and Technology
Journal of Environmental Engineering (United States) | Year: 2012

Tetramethylammonium hydroxide (TMAH) is widely used in manufacturing thin-film transistor liquid crystal displays (TFT-LCD) and semiconductors. Because of its toxicity and nitrogen content, TMAH-containing wastewater has to be properly treated before discharge. In this study, several commercial activated carbons were characterized and used for TMAH adsorption. Activated carbon with micropores showed higher adsorption capacity for TMAH. The adsorption kinetics could be represented by pseudo-second-order model, and the Langmuir model fitted the adsorption of TMAH on activated carbon under different pH adsorption well. Higher pH was favorable for TMAH adsorption, while there was no TMAH adsorption at pH 4.7±0.2. The adsorption was spontaneous and exothermic. Exhausted carbon could be easily regenerated by 0.1 N HCl, with no considerable reduction in performance even after five cycles of adsorption-desorption. It was proposed that electrostatic interaction was the main mechanism of TMAH adsorption on the activated carbon. © 2012 American Society of Civil Engineers.

Sari Dewi D.R.,Widya Mandala Surabaya Catholic University
ARPN Journal of Engineering and Applied Sciences | Year: 2016

QFD is a methodology that helps translating customer desires into technical specifications. Rating assessment in determining the relationship between customer need and engineering characteristics are often very subjective in QFD. QFD also assume that customer satisfaction is determined linearly with the need of customers. Yet according to the model of Kano, the increase in customer satisfaction is not linear with the need of customers. This study contributes to application the mathematical modeling to maximize customer need simultaneously in minimizing customer dissatisfaction to assign product development resources. The relationship between consumer desire and technical characteristics were obtained by regression. The model was applied to cabinet design. Results showed that the output obtained by the model can assign existing resources to improve customer satisfaction and dissatisfaction. © 2006-2016 Asian Research Publishing Network (ARPN).

Kurniawati H.A.,National Taiwan University of Science and Technology | Ismadji S.,Widya Mandala Surabaya Catholic University | Liu J.C.,National Taiwan University of Science and Technology
Bioresource Technology | Year: 2014

This study aims to investigate the harvesting of microalgae by dispersed air flotation (DiAF) using natural biosurfactant saponin as the collector and chitosan as the flocculant. Two types of microalgae, Chlorella vulgaris and Scenedesmus obliquus, were used in this study. It was observed that saponin was a good frother, but not an effective collector when used alone for flotation separation of algae. However, with the pre-flocculation of 5. mg/L of chitosan, separation efficiency of >93% microalgae cells was found at 20. mg/L of saponin. Removal efficiency of >54.4% and >73.0% was found for polysaccharide and protein, respectively at 20. mg/L of saponin and chitosan each. Experimental results show that DiAF using saponin and chitosan is effective for separation of microalgae, and algogenic organic matter (AOM). It can potentially be applied in the integrated microalgae-based biorefinery. © 2014 Elsevier Ltd.

Ong L.K.,Widya Mandala Surabaya Catholic University | Effendi C.,Widya Mandala Surabaya Catholic University | Kurniawan A.,Widya Mandala Surabaya Catholic University | Lin C.X.,University of Queensland | And 2 more authors.
Energy | Year: 2013

Catalyst-free biodiesel production from non-edible Ceiba pentandra (kapok) oil via supercritical methanol transesterification was demonstrated in this work. The supercritical transesterification experiments were performed in a batch reactor at temperatures of 250-350°C, pressures of 10-18MPa, reaction times of 120-600s, and methanol to oil molar ratios of 15:1-35:1. Response surface methodology (RSM) and four-way analysis of variance (ANOVA) were applied for the design and optimization of the experiments with respect to temperature, pressure, reaction time, and molar ratio of methanol to oil simultaneously. The response (i.e., FAME yield) was fitted by a quadratic polynomial regression model using least square analysis in a five-level-four-factor central composite design (CCD). The optimum conditions were found as follows: methanol to oil molar ratio of 30:1, temperature of 322°C, pressure of 16.7MPa, and reaction time of 476s with FAME (fatty acid methyl ester) yield of 95.5%. The significance of the reaction parameters toward FAME yield was in the order of methanol to oil molar ratio>reaction time>pressure>temperature. © 2013 Elsevier Ltd.

Kurniawan A.,Widya Mandala Surabaya Catholic University | Ismadji S.,Widya Mandala Surabaya Catholic University
Journal of the Taiwan Institute of Chemical Engineers | Year: 2011

Low cost activated carbon was prepared from the press-cake residue of Jatropha curcas L. The effectiveness of this activated carbon and its modified forms (chemical and thermal activation) was evaluated for methylene blue (MB) dye removal from aqueous solution. Adsorption experiments were conducted in batch system at various pH and temperatures. The widely used isotherm models, Langmuir and Freundlich, were employed to represent equilibrium data. Kinetic data were analyzed using pseudo-first order and pseudo-second order model. Thermodynamic properties (ΔG0, ΔH0 and ΔS0) of the adsorption of methylene blue onto Jatropha carbons were also obtained. The thermal activated carbon (JAC-3) was more effective for MB dye removal compared to chemical (JAC-2) and parent (JAC-1) activated carbon. © 2011 Taiwan Institute of Chemical Engineers.

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