Nurul Widiastuti

Biopolymer-based electrolyte membranes from chitosan incorporated with montmorillonite-crosslinked GPTMS for direct methanol fuel cells

A composite membrane was fabricated from biopolymer chitosan and montmorillonite (MMT) filler as an alternative membrane electrolyte for direct methanol fuel cell (DMFC) application. To first improve the organic–inorganic interfacial morphology, the pristine MMT was pre-treated using 3-glicidoxy propyltrimethoxysilane (GPTMS) surface modifier to produce organophilic MMT (O-MMT). The GPTMS modified MMT was mixed with chitosan in acetic acid solution and cast into membranes. SEM images and FTIR analysis showed that the O-MMT was successfully incorporated into the chitosan polymer matrix. Water and methanol uptake of the Ch/O-MMT composite membranes decreased with increasing O-MMT loadings, but the ion exchange capacity (IEC) value increased. The Ch/O-MMT with 5 wt% O-MMT loading exhibited the best methanol permeability and proton conductivity characteristics among the other Ch/O-MMT membranes, which were 3.03 × 10−7 cm2 s−1 and 4.66 mS cm−1, respectively. All the results obtained from this study can be used to conclude that the chitosan membrane with O-MMT filler is a promising high performance PEM candidate for DMFC application.

Hubungan antara kekonduksian proton, sifat hidrofil dan kestabilan termal atas membran komposit kitosan/montmorillonit dengan modifikasi GPTMS dan prestasinya dalam sel bahan api metanol langsung

Chitosan based inorganic hybrid membrane is a promising organic–inorganic hybrids for the development of high performance proton exchange membrane (PEM). The immobilization of modified montmorillonite (MMT) using GPTMS within chitosan matrix would possess superior physicochemical characteristics due to more hydrogen bonding formation introduced by GPTMS. Therefore, higher number hydrogen bond formation can be expected in Ch/MMT-GPTMS membrane rather than in pure Ch membrane. A fully hydrated membrane at elevated temperatures is desirable for efficient proton conduction in the membranes. It remains a critical challenge to maintain proper hydration of the membranes for the operation of the direct methanol fuel cell (DMFC). The microstructure obtained by SEM for composites showed that filler was successfully incorporated and relatively well dispersed in the chitosan polymer matrix. The role of surface modification of MMT filler by GPTMS have increase the functional group that can form hydrogen bonding which suitable for interaction with water. High water uptake is favourable for high performance PEM to facilitate great numbers of protons hopping and diffusion through the membrane. In addition, greater hydrogen bonding formation would lead to the tighter packing of composite membrane, resulting in higher bonding strength and higher thermal resistance. The Ch/MMT-GPTMS composite membrane with 5 wt% filler loading exhibited the best proton conductivity are 4.66 mScm-1, with water contact angle value of 64.73°. A maximum power density of 0.24 mWcm-2 was obtained with a 2M methanol feed. The relationship of water contact angle, water upake, membrane swelling, thermal stability, and proton conductivity shown suitable trend, it means that all quality of them are related to the hydrophilicity properties.

Membran campuran daripada poli(eugenol sulfonat) dan polieterimida sulfonat yang menjanjikan untuk sel bahan api metanol langsung

A new polymeric membrane blended from sulfonated polyetherimide (SPEI) and poly(eugenol sulfonate) (PES) was prepared as proton exchange membrane (PEM) for direct methanol fuel cell (DMFC). The membrane was characterized by Fourier Transform Infrared Spectroscopy (FTIR), thermogravimetric analysis (TGA) and Scanning Electronic Microscopy (SEM). Ion exchange capacity (IEC), proton conductivity, methanol barrier, water uptake, water contact angle and mechanical strength of the membrane was also being determined. The new PES/SPEI membrane with 3 wt.% PES and 20 wt.% SPEI show higher IEC, water uptake, proton conductivity and methanol barrier properties as compared to Nafion 117 membrane. As a conclusion, the results indicate that the SPEI/PES membrane has potential to be employed as PEM for DMFC application.

Modification of chitosan membranes with nanosilica particles as polymer electrolyte membranes

Chitosan has been widely used as polymer matrix for Polymer Electrolyte Membrane (PEM) application replacing Nafion which has shortcomings in terms of high methanol permeability that degrades the performance of fuel cells. Chitosan membranes modification is performed by adding nanosilica to prevent methanol transport through the membrane. Nanosilica is synthesized by sol-gel method and the particle diameter is obtained by analysis using Breunner Emmet Teller (BET) that is 6.59 nm. Nanosilica is mixed with chitosan solution to obtain nanosilica-chitosan as polymer electrolyte membrane. The membranes are synthesized through phase inversion method with nanosilica composition including 0; 0.5; 1; 2; 3; 5; and 10% w/w of chitosan. Characterization of the membranes indicate that the results of water swelling, proton conductivity and methanol permeability of the membrane with 3% nanosilica respectively were 49.23%, 0.231 S/cm, and 5.43 x 10−7 cm2/s. Based on the results of membrane selectivity calculation, the o...

Solvothermal and electrochemical synthetic method of HKUST-1 and its methane storage capacity

A comparison synthetic strategy of Metal-Organic Frameworks, namely, Hongkong University of Techhnology-1 {HKUST-1[Cu3(BTC)]2} (BTC = 1,3,5-benzene-tri-carboxylate) through solvothermal and electrochemical method in ethanol:water (1:1) has been conducted. The obtained material was analyzed using powder X-ray diffraction, Scanning Electron Microscopy (SEM), Fourier Transform Infrared Spectroscopy (FTIR), Thermo-Gravimetric Analysis (TGA) and Surface Area Analysis (SAA). While the voltage in the electrochemical method are varied, ranging from 12 to 15 Volt. The results show that at 15 V the texture of the material has the best degree of crystallinity and comparable with solvothermal product. This indicated from XRD data and supported by the SEM image to view the morphology. The thermal stability of the synthesized compounds is up to 320 °C. The shape of the nitrogen sorption isotherm of the compound corresponds to type I of the IUPAC adsorption isotherm classification for microporous materials with BET surface area of 629.2 and 324.3 m2/g (for solvothermal and electrochemical product respectively) and promising for gas storage application. Herein, the methane storage capacities of these compounds are also tested.

AMMONIUM REMOVAL USING BATCH AND FIXED BED COLUMN BY ZEOLITE A-CARBON SYNTHESIZED FROM COAL BOTTOM ASH

Bottom ash is coal ash waste released due to the usage of coal in the electric power plant. According to data reported by Ministry of Environment Indonesia, bottom ash waste was about 58 ton/day (Said, 2010). The coal ash waste is clasified as hazardous and dangerous waste under Indonesian regulation (PP85/1999), because it could cause self burning and negative impact to human health. Therefore, the ash waste must be utilised such as by converting the ash to become zeolite-carbon. On the other hand, ammonium is one of the significant contaminant of wastewater. The excessive presence of ammonium could cause eutrophication of stuaries, rivers, lakes and coastal seas, corrosion or biological fouling problem in industrial water system (Widiastuti et al, 2011). Zeolite is a potensial material to remove ammonium from wastewater. The zeolite framework generates one negative charge on the framework owing to the substitution of aluminum (Al3+) atom for silicon (Si4+) in the three dimensional framework of aluminosilicate tetrahedral (Englert and Rubio, 2005). The negative charge in the zeolite framework is balanced by cations such Na+, that can be exchanged by the ammonium ion. Zeolite A is a type of zeolite that has Si/Al ratio of 1 resulting in high ion exchange. This research focuses on the effectiveness of ammonium removal using batch and fixed bed column by zeolite A-carbon synthesized from coal bottom ash. The zeolite A-carbon was synthesized by fusion method in nitrogen atmosphere followed by a hydrothermal treatment (Yanti, 2009). Adsorption capacity of the synthesized zeolite was determined in batch by varying contact time (Figure 1), initialconcentration of ammonium and pH. The theoritical aspect of adsorption including adsorption isotherm and kinetics were also studied (Table 1).

Adsorption of Cu(II) Ion on Zeolite A Synthesized from Coal Bottom Ash in Fixed Bed Column System

Coal usage as a source of energy in Indonesia is increasing nowdays. In 2003, the usage of coal in the electric power plant was about 14.1% of total energy and in 2025, it will be over 34.6% (Yanti, 2009). The increase in coal usage causes the increase of coal ash waste, which was up to 500-1000 ton per day (Said, 2010). The discharged coal waste may cause self burning or self exploding and have negative effect to human health. Therefore, under Indonesian regulation (PP85/1999), coal ash is clasified as hazardous and dangerous waste (Said, 2010).In order to reduce the piling up, coal ash must be utilised. One of potential utilization of coal ash is to convert the ash to become zeolite minerals.