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Chitosan-charcoal composite was applied as a media to treat tannery effluent. The composite was prepared by a simple solution-evaporation method and the morphology of the prepared composite was characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD). Adsorption of chromium (Cr) was investigated by varying the contact time between adsorbate (Cr) and composite, pH of solution and dose of composite. The concentration of Cr was determined by atomic absorption spectroscopy (AAS). Removal of Cr was found to be dependent on pH and maximum adsorption was observed at pH 4.0. The optimum dose and contact time for Cr treatment was 40 g/L and 250 minutes respectively. The results showed that prepared composite can be used efficiently for the treatment of tannery wastewater containing chromium.

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Carbon nanotubes (CNTs) were grown over 12Mo:18Co:70MgO catalyst at 500, 700 and 900° C from C2H2 decomposition for 30 minutes using chemical vapor deposition (CVD) method. The highest yield of CNTs was observed at 700O C. The lowest diameter of CNTs appeared at 900° C. Quadruple mass spectroscopy (QMS) study on the species generated from the catalytic decomposition of C2H2 identified that the catalyst consumed C species during the growth stage of CNTs. The consumption period of C varied with temperature and showed a close relationship with the carbon yield. At 500, 700 and 900°C, the consumption periods were 12, 35 and 20 min, respectively, and the corresponding carbon yields were 7, 385 and 89%. From the XRD analysis of catalyst surface, and XRD and Raman analysis of the CNTs, it was realized that Co particles released from Co3O4, CoMoO4 and CoO-MgO were participated in CNTs growth at 500, 700 and 900° C, respectively. The Co particles acted as the transporting medium of carbon to grow CNTs. The tubes are MWNTs and grown by tip growth mode. Bangladesh J. Sci. Ind. Res. 42(2), 105-114, 2007

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