The possible utilization of rice husk activated carbon as an adsorbent for the removal of methylene blue dye from aqueous solutions has been investigated. In this study, activated carbons, prepared from low -cost rice husk by sulfuric acid and zinc chloride activation, were used as the adsorbent for the removal of methylene blue, a basic dye, from aqueous solutions. Effects of various experimental parameters, such as adsorbent dosage and particle size, initial dye concentration, pH and flow rate were investigated in column process. The maximum uptakes of methylene blue by activated rice husk carbon at optimized conditions (particle sizes: 140 µm; Flow rate: 1.4 mL/min; pH: 10.0; initial volume of methylene blue: 50 mL and initial concentration of methylene blue: 4.0 mg/L etc.) were found to 97.15%. The results indicate that activated carbon of rice husk could be employed as low-cost alternatives to commercial activated carbon in waste water treatment for the removal of basic dyes. This low cost and effective removal method may provide a promising solution for the removal of crystal violet dye from wastewater.

Aerosol particulate matter (PM 10 and PM 2.5 ) and trace gases (SO 2 , NO 2 , CO and O 3 ) were sampled at five locations in greater Dhaka, Bangladesh, between January and April 2006. Particulate matter was collected on microfiber filters with a low-volume sampler, and trace gases (SO 2 , NO 2 , and O 3 ) were collected with an impinger equipped with PM samplers. Carbon monoxide was determined using the Indicator Tube method. The total average concentrations of SO 2 , NO 2 , CO, and O 3 were 48.3, 21.0, 166.0 and 28 μg m -3 , respectively. The total average concentrations of SO 2 and NO 2 were much lower than the annual average guideline values of the World Health Organization (WHO). The total average O 3 concentration was also much lower than the daily maximum values established by WHO (average of 100 μg m -3 for an 8-h sample). The total average concentrations of five sites were 263, 75.5 and 66.2 μg m -3 for SPM, PM 10 and PM 2.5 , respectively. The mass of PM 2.5 is approximately 88% of the PM 10 mass, indicating that fossil fuel is the main source of PM in Dhaka. An atomic absorption spectrophotometer was used to determine the heavy metal concentrations in the PM 2.5 size fraction. The total average concentrations of As, Cd, Cu, Fe, Pb, and Zn in PM 2.5 were 6.3, 13, 94, 433, 204, and 381 ng m -3 , respectively. The Pb concentration in Dhaka shows a decreasing tendency, presumably due to the ban on the use of leaded fuel. The overall trace metal concentrations in Dhaka are higher than those in European (e.g., Spain, Norway) and East Asian (e.g., Taiwan) locations, but lower than those measured in Southeast Asian (Kanpur, Delhi, Mumbai, India; Lahore, Pakistan) cities.

Malnutrition may not itself give rise to glucose intolerance, and serum magnesium deficiency seems to be a consequence rather than a cause of diabetes mellitus.

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