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Boey P.-L.,Universiti Sains Malaysia | Ganesan S.,Universiti Sains Malaysia | Maniam G.P.,Universiti Malaysia Pahang | Khairuddean M.,Universiti Sains Malaysia | Efendi J.,Ibnu Sina Institute for Fundamental Science Studies
Energy Conversion and Management | Year: 2013

Studies on heterogeneous acid catalysts for converting free fatty acids into biodiesel have been intensified over the years. This paper focuses on the optimization of a new catalyst system, ferric-alginate as a heterogeneous acid catalyst to esterify lauric acid into methyl laurate. Methanol to lauric acid molar ratio and catalyst amount was optimized using response surface methodology (RSM). The best reaction conditions to achieve methyl laurate yield of 99% was found to be 0.16:1 ferric-alginate to lauric acid mass ratio and 16:1 methanol to lauric acid molar ratio. The reaction time and temperature was fixed at 3 h and methanol refluxing temperature, respectively. The optimized reaction conditions were also used to esterify palm fatty acid distillate to give 89% methyl esters conversion. The acid value of palm fatty acid distillate (PFAD) was reduced from 228 to 0.8 mg KOH/g PFAD. © 2012 Elsevier Ltd. All rights reserved.


Eisazadeh A.,University of Technology Malaysia | Kassim K.A.,University of Technology Malaysia | Nur H.,Ibnu Sina Institute for Fundamental Science Studies
Applied Clay Science | Year: 2012

The poor engineering properties of soils containing high amounts of clay minerals can be altered through chemical stabilization, resulting in a material suitable for geotechnical applications. The primary objective of this research was to study the time-dependent changes in the structure of lime stabilized montmorillonitic and lateritic clays using solid state nuclear magnetic resonance (SS-NMR) and Fourier transform infrared (FTIR) spectroscopy. The 29Si and 27Al MAS NMR spectra of montmorillonite dominated soils indicated that the reaction products of the attack on the tetrahedral sheets were mainly responsible for the formation of new composites that bound the soil particles together. Furthermore, the coating of iron (hydr)oxides on the surface of the laterite clay particles retarded the pozzolanic reactions. The presence of lime in the soil-stabilizer matrix was also confirmed by a new band observed in the FTIR spectra. From the geotechnical point of view, the lime treated bentonite showed the highest degree of improvement with an approximately 11-fold strength increase in comparison to the natural soil within 8-month curing periods. © 2012 Elsevier B.V.


Setiabudi H.D.,University of Technology Malaysia | Jalil A.A.,University of Technology Malaysia | Triwahyono S.,Ibnu Sina Institute for Fundamental Science Studies | Triwahyono S.,University of Technology Malaysia
Journal of Catalysis | Year: 2012

The effects of iridium loading on the properties of Ir/Pt-HZSM5 and n-pentane isomerization were studied. XRD, IR, and NMR results indicated that increasing iridium loading did not much change the properties of catalysts, but eliminated the perturbed silanol groups at 3700 and 3520 cm -1, whereas IR and ESR spectroscopy confirmed that increasing iridium loading continuously decreased the permanent Lewis and Bronsted acid sites and inhibited the formation of protonic acid sites induced by hydrogen. At low iridium loading (0-0.3 wt%), cracking process proceed through dimerization-cracking step, whereas high iridium loading (0.5-2.0 wt%) reduces the contribution of dimerization-cracking step and promotes the contribution of hydrogenolysis. The excessive amount of iridium loading, with the presence of a low amount of active protonic acid sites and hydrogen gas, accelerated the hydrogenolysis process. The activity of Ir/Pt-HZSM5 was marginal in the absence of hydrogen, showing the dependence of activity on promotive effect of hydrogen. © 2012 Elsevier Inc. All rights reserved.


Kimi M.,University of Technology Malaysia | Yuliati L.,Ibnu Sina Institute for Fundamental Science Studies | Shamsuddin M.,University of Technology Malaysia
International Journal of Hydrogen Energy | Year: 2011

A series of Cd0.1SnxZn0.9-2xS solid solution was successfully synthesized by hydrothermal method and employed as photocatalyst for photocatalytic hydrogen evolution under visible light irradiation. The structures, optical properties and morphologies of the solid solutions were studied by X-ray diffraction, diffuse reflectance UV-visible spectroscopy and field emission scanning electron microscopy. From the characterizations, it was confirmed that Sn can form solid solution with Cd 0.1Zn0.9S and the high crystallinity can be maintained as well. Among all samples, the highest photocatalytic activity was observed on Cd0.1Sn0.01Zn0.88S photocatalyst, with average rate of hydrogen production 3.52 mmol/h, which was ca. 1.5 times higher than the Cd0.1Zn0.9S photocatalyst. In addition to the high activity, the Cd0.1Sn0.01Zn0.88S also showed high stability at long irradiation time. The role of Sn in preventing electron-hole recombination and photocorrosion was proposed. © 2011, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.


Kimi M.,University of Technology Malaysia | Yuliati L.,Ibnu Sina Institute for Fundamental Science Studies | Shamsuddin M.,University of Technology Malaysia
Journal of Photochemistry and Photobiology A: Chemistry | Year: 2012

A series of Cu-doped Cd 0.1Zn 0.9S solid solution with various amounts of Cu dopant was successfully prepared by hydrothermal method. The properties and the photocatalytic activity of the prepared samples for hydrogen production under visible light irradiation were compared to those prepared by co-precipitation method. The Cu-doped Cd 0.1Zn 0.9S samples prepared by hydrothermal method showed both improved crystallinity and photoabsorption ability as compared to the undoped sample. On the other hand, even though Cu-doped Cd 0.1Zn 0.9S prepared by co-precipitation method also showed improved photoabsorption ability in the visible light region, the samples showed poor crystallinity compared to the undoped one. With the same amount of Cu dopant, all samples prepared by hydrothermal method were found to exhibit higher photocatalytic activity for hydrogen production than the samples prepared by co-precipitation method. It was revealed that the amount of Cu dopant, crystallinity and narrow band gap energy are important factors to obtain highly active and stable photocatalysts. © 2012 Elsevier B.V. All rights reserved.


Jalil M.A.,Ibnu Sina Institute for Fundamental Science Studies
International journal of nanomedicine | Year: 2011

BACKGROUND: A novel nanomicro syringe system was proposed for drug storage and delivery using a PANDA ring resonator and atomic buffer. A PANDA ring is a modified optical add/drop filter, named after the well known Chinese bear. In principle, the molecule/drug is trapped by the force generated by different combinations of gradient fields and scattering photons within the PANDA ring. A nanomicro needle system can be formed by optical vortices in the liquid core waveguide which can be embedded on a chip, and can be used for long-term treatment. By using intense optical vortices, the required genes/molecules can be trapped and transported dynamically to the intended destinations via the nanomicro syringe, which is available for drug delivery to target tissues, in particular tumors. The advantage of the proposed system is that by confining the treatment area, the effect can be decreased. The use of different optical vortices for therapeutic efficiency is also discussed.


Hasan M.H.,University of Malaya | Mahlia T.M.I.,University of Malaya | Mahlia T.M.I.,University of Syiah Kuala | Nur H.,Ibnu Sina Institute for Fundamental Science Studies
Renewable and Sustainable Energy Reviews | Year: 2012

The global energy consumption is likely to grow faster than the population growth. The fuel consumption was growing from 6630 million tons of oil equivalents (Mtoe) in 1980 to 11,163 Mtoe in 2009. This projected consumption will increase 1.5% per year until 2030 and reach 16,900 Mtoe and the main drivers of this growth are mostly developing countries in Asia. Indonesia is one of the developing countries and energy supply is an important factor for all-around development. The country's energy consumption still depends on non-renewable energy such as crude oil, coal and natural gas as sources of energy. Utilization of fossil fuel continuously contributes to huge amount of greenhouse gases emission that leads to climate change. Facing such an unfavorable situation, the government of Indonesia prioritizes on energy supply securities by diversification of energy resources. The energy mixes in Indonesia based on five main resources; these are crude oil, natural gas, coal, hydropower, and renewable energy. Although the country encourages utilizing renewable energy, the contribution is only around 3%. Considering natural condition and geography, this country is blessed with great potential of renewable energy such as solar energy, wind energy, micro hydro and biomass energy. Noting the potential of renewable and sustainable energy resources in the country, the government must pay more attention on how to utilize it. Many efforts have been done to promote renewable energy such as to create energy policy and regulations, yet it still did not give any satisfactory result. Government, non-government agencies and the public should take a more proactive step to promote and use renewable energy in order to achieve the secure and environmentally sustainable energy resources. © 2011 Elsevier Ltd. All rights reserved.


Mohd Ekhsan J.,Ibnu Sina Institute for Fundamental Science Studies | Lee S.L.,Ibnu Sina Institute for Fundamental Science Studies | Nur H.,Ibnu Sina Institute for Fundamental Science Studies
Applied Catalysis A: General | Year: 2014

Silica-titania modified by impregnation of niobium oxide and phosphoric acid (P/Nb/Ti-Si) possesses both oxidative active site and Brønsted acid. Results of the catalytic evaluation in consecutive transformation of 1-octene to 1,2-octanediol through formation of 1,2-epoxyoctane suggested that Nb 2O5 was a more important oxidative active site compared to tetrahedral Ti species. Besides, co-existence of Nb2O5 and PO4 3- modifiers was crucial for Brønsted acidity formation. However, the amount of Brønsted acid created was strongly dependent on the synthesis method that was greatly influenced by the interfacial interaction between Nb2O5 and PO 4 3- in the material to produce NbOPO4 3-H+ bonding. It has been demonstrated that the P/Nb/Ti-Si was an excellent oxidative-acidic bifunctional catalyst to produce 1,2-octanediol. © 2013 Elsevier B.V.


See H.H.,University of Basel | See H.H.,Ibnu Sina Institute for Fundamental Science Studies | Stratz S.,University of Basel | Hauser P.C.,University of Basel
Journal of Chromatography A | Year: 2013

A flow-through arrangement for electrodriven extraction across a polymer inclusion membrane was developed. Sample introduction into the donor chamber was continuous, while the acceptor solution was stagnant. By adjustment of the total volume of the donor solution pumped through the cell the best compromise between enrichment factor and extraction time can be set. The enriched extract was analyzed by capillary electrophoresis with contactless conductivity detection. Membranes of 20. μm thickness were employed which consisted of 60% cellulose triacetate as base polymer, 20% o-nitrophenyl octyl ether as plasticizer, and 20% Aliquat 336. By passing through 10. mL of sample at a flow rate of 1. mL/min the model analytes glyphosate (a common herbicide) and its major metabolite aminomethylphosphonic acid could be transported from the aqueous donor solution to the aqueous acceptor solution with efficiencies >87% in 10. min at an applied voltage of 1500. V. Enrichment factors of 87 and 95 and limits of detection down to 43 and 64. pg/mL were obtained for glyphosate and aminomethylphosphonic acid, respectively. The intra- and interday reproducibilities for the extraction of the two compounds from spiked river water were about 6 and 7% respectively when new membranes were used for each experiment. For consecutive extractions of batches of river water with a single piece of membrane a deterioration of recovery by about 16% (after 20 runs) was noted, an effect not observed with purely aqueous standards. © 2013 Elsevier B.V.


Ati A.A.,Ibnu Sina Institute for Fundamental Science Studies | Othaman Z.,Ibnu Sina Institute for Fundamental Science Studies | Samavati A.,Ibnu Sina Institute for Fundamental Science Studies
Journal of Molecular Structure | Year: 2013

Improving the magnetic response of nanocrystalline nickel ferrites is the key issue in high density recording media. A series of cobalt substituted nickel ferrite nanoparticles with composition Ni(1-x )CoxFe2O4, where 0.0 ≤ x ≤ 1.0, are synthesized using co-precipitation method. The XRD spectra revealed the single phase spinel structure and the average sizes of nanoparticles are estimated to be 16-19 nm. These sizes are small enough to achieve the suitable signal to noise ratio in the high density recording media. The lattice parameter and coercivity shows monotonic increment with the increase of Co contents ascribed to the larger ionic radii of the cobalt ion. The specific saturation magnetization (Ms), remanent magnetization (Mr) and the coercivity (Hc) of the spinel ferrites are further improved by the substitutions of Co+2 ions. The values of Ms for NiFe 2O4 and CoFe2O4 are found to be 43.92 and 78.59 emu/g, respectively and Hc are in the range of 51-778 Oe. The FTIR spectra of the spinel phase calcinated at 600 C exhibit two prominent fundamental absorption bands in the range of 350-600 cm-1 assigned to the intrinsic stretching vibrations of the metal at the tetrahedral and octahedral sites. The role played by the Co ions in improving the structural and magnetic properties are analyzed and understood. Our simple, economic and environmental friendly preparation method may contribute towards the controlled growth of high quality ferrite nanopowders, potential candidates for recording. © 2013 Elsevier B.V. All rights reserved.

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