The effect of alumina addition of 5–30% by weight on phase transformation and crystallisation properties of refractory cordierite ceramics prepared from amorphous rice husk silica followed by sintering treatment at temperature of 1230 °C was studied. The crystallinity and microstructure of the samples were characterised using X-ray diffraction (XRD) coupled with Rietveld analysis, scanning electron microscopy (SEM), respectively. Some physical properties include density, porosity, hardness, bending strength, and thermal expansion coefficient of the samples with different alumina additions were measured. The results show that addition of alumina promoted crystallisation of cordierite into crystalline spinel, corundum, cristobalite, in which with addition of 10–30% alumina, the cordierite phase was practically undetected. Addition of alumina was also found to increase the amount of spinel, while corundum and cristobalite decreased following alumina addition of 10–30%. The presence of spinel, corundum, and cristobalite resulted in increased of density, hardness, bending strength and thermal expansion coefficient, while for porosity, the opposite was observed. Thermal expansion coefficient of the samples with alumina addition of 15–30% reach the relatively constant value of 9.5 × 10−6/°C, with the main crystalline phase was spinel, accompanied by corundum and cristobalite in smaller quantities

Oriental Journal of Chemistry is a peer reviewed quarterly research journal of pure and applied chemistry. It publishes standard research papers in almost all thrust areas of current chemistry of academic and commercial importance. It provides a platform for rapid publication of quality research papers, reviews and chemistry letters. Oriental Journal of Chemistry is abstracted and indexed in almost all reputed National and International agencies.

In this study, nano-size MgO was synthesized from seawater and bittern obtained from local salt industry in Pamekasan, Madura, Indonesia, using electrochemical method. The main purpose was to study the effects of seawater pre-concentration and bittern dilution on the structure and morphology of the MgO nanoparticles produced. Electrochemical process was performed in a two-compartment electrochemical cell with a fixed potential of 18 V, for 4 h at ambient temperature, and without adjusting the pH. Solid Mg(OH)₂ produced was converted into MgO by calcination treatment at 500 °C for 4 h, and then characterized using XRD and SEM technique. The characterization results revealed that spherical or cubic crystalline MgO were successfully produced, with the particle sizes in the range of 60–100 nm.

Oriental Journal of Chemistry is a peer reviewed quarterly research journal of pure and applied chemistry. It publishes standard research papers in almost all thrust areas of current chemistry of academic and commercial importance. It provides a platform for rapid publication of quality research papers, reviews and chemistry letters. Oriental Journal of Chemistry is abstracted and indexed in almost all reputed National and International agencies.