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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.

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.

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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