ABSTRACT
Background: the phenomenon of dust is a serious environmental problem in dry and semi dry regions. It has a destructive effect for the residents of such regions. Over two-thirds of Iran is in areas of dry and semi-dry climate conditions
Methods: in this research, dust fall measurements were taken in 41 stations across Yazd city using a marble dust collector [MDCO] located in different parts of the city. Next, the chemical characteristics of dust were determined using the XRF method. Finally, levels of dust fall across the 4 seasons of the year and status of the constituent elements of dust were determined through ArcGIS software and the Kriging technique. The Raster calculator function was used to make determinations of the effects of dust fall at each of the stations over the course of the year. Remote sensing system, along with maps taken from Landsat and the band combination technique were processed using ENVI software to extract vegetation density and building density maps of the studied region
Results: results showed that spring had the highest level of dust fall with a value of 200 g/cm[2]. In total, in 109 km[2] of the studied region had average dust fall of 110 g/m[2] that contributed to 12 057 tons of dust over Yazd city in 2015. The constituent elements of the dust fall according to decreasing amounts were as follows: Si>Ca>Al>C>Mg>Fe>K>Na>S>Ti>Cl>P>Mn>Sr>Zn
Conclusion: these results indicate accuracy of the Kriging technique for application in dust zoning. The factors of vegetation and green space were determined as effective on adsorbing dust. Increased building density and height of buildings also contributed to development of dust fall
ABSTRACT
Background and Aim: Activated carbon is a most common adsorbent. By emerging of new technologies, the activated carbon production methods need to be improved. The aim of this study was producing powdered activated carbon from Peganum Harmala seed under ultrasound waves for activation and its application for chromium removal from aqueous solutions
Materials and Methods: This experimental study was conducted in a batch reactor. The Peganum Harmala seeds were used for activated carbon production and Ultrasonic waves were used to activation. The BET test was done in order to determine of the specific surface area of produced activated carbon. The most important variables affecting the adsorption process were examined. For Cr[VI] determining UV/VIS Spectrophotometer T80+ at a wavelength of 540 nm was used. Data analysis was performed by Excel software
Results: The BET test results showed that the specific surface area of produced activated carbon is 442m[2]/g. The optimum pH of solution to adsorption process by both raw powder of Peganum Harmala seeds and produced powdered activated carbon adsorbents was equal 2. Adsorption data for both adsorbents were best fitted to the pseudo-second order kinetic and parameter of K[2] for the produced powdered activated carbon was obtained two times more than K[2] for raw powdered Peganum Harmala seed
Conclusion: The results showed that ultrasound is very effective in activation of carbon and produced activated carbon have high adsorption rate and specific surface area, it and can be used as an appropriate adsorbent for removal of hexavalent chromium