Publications (2)0 Total impact
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Article: Influence of weekdays, weekends and bandhas on surface ozone in Kathmandu valley
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ABSTRACT: In this paper, variations of nitric oxide (NO), nitrogen dioxide (NO2), oxides of nitrogen (NOx), ozone (O3) and total oxidant (OX) concentration in ambient air of Kathmandu valley are presented. O3 behavior during weekdays, weekends and bandhas (general strike) is analyzed and the mechanism related to it is discussed. The increased NO2/OX ratio with increasing NOx concentration and the inverse relation between NOx and O3 imply that the residual O3 remaining after the NO–NO2–O3 reaction chain controlled O3 concentration in the valley atmosphere and the radical channel was likely to have a minor contribution. The higher positive correlation coefficient for O3 variation during weekdays and bandhas, weekdays and weekends suggests common sources for the weekends and bandhas O3 variation. The higher O3 concentration during weekends and bandhas compared to weekdays was due to less destruction of O3. Enhanced reduction in traffic emission levels, enforcement of stringent emission standards within the valley and the surroundings may help to address the O3 problem in the valley atmosphere.Atmospheric Research. -
Article: Vanadium removal from water by waste metal sludge and cement immobilization
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ABSTRACT: The present study was first carried out to investigate the adsorption potential of metal sludge (a waste product of electroplating industry) in removing vanadium from water. The adsorption capacity of metal sludge for vanadium was found 24.8 mg/g at 25 °C. The adsorption was studied as a function of contact time (0.5–10 h), concentration (1.5 × 10−4–9.5 × 10−4 M) and temperature (25 and 45 °C) by batch method. The adsorption has been found to be endothermic and data conform to Langmuir model. The analysis of kinetic data indicates that present adsorption system is a pseudo-first-order process and intraparticle diffusion controlled. After adsorption studies, the metal-laden sludge adsorbent was immobilized into the cement for its ultimate disposal. Physical properties such as initial and final setting time, compressive strength of cement stabilized wastes were tested to see the effect of metal-laden sludge in cement. The results of present study clearly reveal that metal sludge can be fruitfully employed in treating industrial effluents containing vanadium and further safely dispose of by immobilizing it into cement. The proposed technology provides a two-fold advantage of wastewater treatment and solid waste management.Chemical Engineering Journal.
