Stable colloidal tetrapropylammonium manganese oxide ͑TPA-MO͒ was formed by the reduction of tetrapropylammonium permanganate with 2-butanol at room temperature. Thin films of TPA-MO were prepared using the sol-gel process by dip-coating directly onto clean nickel foils followed by heat-treatment under controlled conditions. The microstructure evolution of TPA-MO films at various calcination temperatures was characterized using Brunauer-Emmett-Teller method, X-ray diffraction, and scanning electron microscopy. The performance of these films as supercapacitors was evaluated using cyclic voltammetry in various aqueous electrolytes. These thin films exhibited excellent capacitive behavior with a specific capacitance of 720 F/g. These films also showed good reversibility and cycling stability, losing little more than 20% of their charge capacity after 1500 cycles. 4,5 As compared to other transition metal oxides such as NiO 2 , CoO, RuO 2 , and V 2 O 5 , these materials have received much attention and interest due to the low cost of raw materials, low toxicity, and environmentally friendly character.Studies of Pang et al. 4,5 have shown that sol-gel-derived MnO 2 thin films are a promising electrode material for supercapacitors due to their high reversibility, good cycling stability, and their high specific capacitance of 700 F/g. However, in spite of their favorable characteristics, the potential use of such sol-gel-derived MnO 2 films for fabricating practical devices is limited by the very dilute concentration (10 Ϫ3 M) of the MnO 2 colloidal suspension employed in coatings. Stable nanoparticles of manganese oxides having higher concentrations are difficult to prepare because of the strong tendency of manganese oxides to precipitate or coagulate during synthesis. Any increase in the MnO 2 concentration invariably leads to the destabilization of the colloidal suspension. Considerable efforts have therefore been directed toward exploring alternative precursors and approaches in order to prepare stable colloidal suspensions with higher concentrations of manganese dioxide particles.Recently, stable colloidal manganese oxides with concentrations as high as 0.57 M have been successfully prepared by incorporating tetralkylammonium cations ͑alkyl ϭ ethyl, propyl, and butyl͒ to prevent agglomerization of the negatively charged manganese oxide particles.6 Materials derived from such colloidal manganese oxides are reported to have lamellar structure with tetraalkylammonium cations intercalated between the manganese oxide layers. The manganese oxides have an average oxidation state of 3.70-3.79. 6 The pore size distribution of materials derived from such organic cation template-based manganese oxides can be well controlled by the size of the particles that constitute the templates, which can be subsequently removed by heat-treatment.In this paper, we report on the microstructural characterization of sol-gel-derived tetraproplyammonium manganese oxide ͑TPA-MO͒ thin films on nickel substrates and the electrochemical charact...

A large amount of sago pith waste (SPW) produced by the growing sago industry has become an environmental concern. Instead of disposing as waste, SPW could be converted into a hydrogel and used as a seed germination medium. In this study, a hydrogel was prepared from SPW cellulose fibres via crosslinking with epichlorohydrin (ECH). Fourier transform infrared (FTIR) characterisation showed that pure cellulose fibres extracted from the SPW were successfully crosslinked with ECH to form the hydrogel. Scanning electron microscope (SEM) micrograph of the hydrogel showed a porous microstructure. The optimum hydrogel swelling ratio at 19.9 g g -1 was obtained with 5% w/v SPW cellulose content and 5 ml ECH. In this study, the hydrogel hydration property was demonstrated by using it as a medium for maize seed germination. The germination rate (GR) was observed to be above 70% when SPW cellulose hydrogel alone was used as the medium without the needs for frequent watering.

Currently most of the aerogel-based drug delivery carriers are made from non-biodegradable materials, such as silica. In this study, highly porous cellulose aerogels with Brunauer-Emmett-Teller (BET) surface areas that varied between 22 m 2 g-1 and 525 m 2 g-1 were prepared from a sugarcane bagasse cellulose solution of various concentrations. The potential utility of cellulose aerogels as controlled release carriers was evaluated by loading methylene blue (MB) as a model hydrophilic drug. The MB loading capacity and release kinetic profiles of cellulose aerogels were observed to be substantially influenced by their BET surface areas. Under optimum conditions, a maximum loading capacity of 6.4 mg MB mg-1 cellulose aerogel was achieved with sustained release of MB from cellulose aerogels at physiological pH over a period of 23 h.

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