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Cytotoxicity and haemocompatibility of γ-radiated Hap met the benchmarks according to ISO 10993-5 and ISO 10993-4 standards, respectively. Moreover, extreme antimicrobial (>98%) and moderate (∼34%) antioxidant properties were also exhibited.

A photo-catalytic composite material incorporating rice husk ash (RHA) and TiO2 (RHA:TiO2 = 75:25 and 50:50) has been developed and used to investigate the photodegradation of the well-known dye pollutant, methylene blue (MB). Photodegradation was monitored in the dark and under illumination using a halogen lamp as well as sun light to facilitate photodegradation. Both the dark reaction and photo- mineralization processes were evaluated in terms of kinetic study which revealed the validation of first-order kinetics. A parallel measurement of chemical oxygen demand (COD) was also performed for a better understanding of the degradation process. The higher degradation rate in the sun light offers an easy-to-use and environment friendly approach for the treatment of dye stuffs. However, the overall phototdegradation mechanism involved the participation of both the anodic (h+ consumption) and cathodic (e- consumption) processes which were responsible for the degradation of MB and consumption of dissolved oxygen respectively. Key words: Photo-degradation; Composite plate; Rice husk ash, Methylene blue; Adsorption. DOI: http://dx.doi.org/10.3329/bjsir.v46i1.8100 Bangladesh J. Sci. Ind. Res. 46(1), 17-26, 2011

Water in oil (W/O) microemulsions are simple preparative route for nanoparticles where water droplets dispersed in oil stabilized by surfactant or surfactant and cosurfactant monolayer act as nanoreactors to carry out chemical reactions. In this work, silver nanoparticles (AgNPs) were prepared in W/O microemulsions of cetyltrimethylammonium bromide (CTAB) and triton X-100 (TX-100) by using AgNO 3 and NaBH 4 as a precursor salt and reducing agent, respectively. To prepare microemulsions, CTAB or TX-100, 1-pentanol, cyclohexane and water were mixed with different molar ratio. AgNPs were prepared with different [AgNO 3 ] in microemulsions of CTAB with fixed water to surfactant ratio (W o ). Average particle sizes were determined from dynamic light scattering (DLS) measurements. AgNPs prepared from microemulsions of CTAB were unstable while from TX-100, NPs were stable. Aggregation kinetics was investigated by measuring the absorbance at definite time intervals at the absorption maximum, λ max of AgNPs in different media under pseudo-first-order conditions. The aggregation behavior was studied at different [AgNO 3 ]: [NaBH 4 ] and W o and the parameters were optimized to ensure formation of stable AgNPs without aggregation in microemulsions. This would help tuning the size, stability, and aggregation kinetics of AgNPs by controlling the nature of the surfactant and composition of the microemulsions.

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IntroductionSanitation remains one of the biggest development challenges in Bangladesh. Now a day, increasing concern for protection of health and environment has caused increased use of ceramic component all over the country. For manufacturing sanitary ware, the crucial state in this process is preparing the casting slip, which determines the moulding time and the quality of the finished products. Clays and kaolin are the principal raw materials which have a large effect on their technological properties for manufacturing sanitary ware (Khalev and Vlasov, 2007). Therefore the content of water and the dispersion of the solid phase should be optimized taking into account subsequent drying and sintering to ensure the maximally high parameters of the product. The main technological operations are as follows: pretreatment of raw materials, preparation of casting and glaze slips, casting a product, its setting, drying, glazing and firing. The chemical composition of the clay raw materials is one of the main indicators for selection of a component for the final mixture. Al 2 O 3 has the largest effect on the properties of ceramic articles. As the Al 2 O 3 content increases the refractoriness and mechanical strength of the material increases.SiO 2 decreases the shrinkage and it also decreases refractoriness of the product. Colouring oxides iron and titanium oxides are strong fluxes, which decrease the viscosity of the liquid phase as well as the mechanical strength of the article (Khalev and Vlasov, 2007). The most effective method for decreasing the viscosity of a ceramic slip with a constant content of the dispersion phase (water) is the use of liquefying additives (electrolytes), which usually are salts of monovalent metals (Pishch et. al., 2006). In this work, sodium silicate was used as electrolyte. Bijoypur clay, red clay, black clay, china clay and ball clay were used to prepare sanitary ware compositions. Sanitary ware used in domestic purpose can be classified as sanitary earthenware and vitreous china ware. It is found that, the range of firing temperature is from 1180 o C to 1200 o C and water absorption value 5-10% for earthenware and below 1% for vitreous china sanitary ware (Singer and Singer, 1963). There are some other basic physical properties such as linear shrinkage, bulk density, chemical compositions of the sanitary ware bodies play the main role in quality control parameters. Modulus of Rupture (MOR) is another important property for sanitary ware body. Investigations revealed the effect of qartzitic clay and kaolinitic clay on the properties of the products.Thus the aim of this work is to develop cost effective and quality vitreous china sanitary ware for domestic use in rural area. Ten different batch compositions were prepared using different ratios of the raw materials. Chemical properties, Investigation on Physico-Chemical Properties of Vitreous China Sanitary Ware from Local ClaysShahnaj Parveen* and Shirin Akter JahanInstitute of Glass and Ceramic Research and Testing (IGCRT), Bangladesh Co...

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Plaster of Paris, a well-known biomaterial, was synthesized from waste eggshells, which were chosen as an available bio-source of calcium.