tailieunhanh - Chemical Pollutants in Air, Water, Soil, and Solid Wastes Phần 8

Ô nhiễm môi trường đất là hậu quả các hoạt động của con người làm thay đổi các nhân tố sinh thái vượt qua những giới hạn sinh thái của các quần xã sống trong đất. | SULFUR DIOXIDE Formula SO2 MW CAS 7446-09-5 a major air pollutant produced when soft coals oils and automobile fuels bum used as a fumigating and bleaching agent colorless gas with a strong suffocating odor liquefies at -10 C solidifies at -72 C soluble in water at 25 C . alcohol ether and chloroform highly toxic and a strong irritant. AIR ANALYSIS AÚ drawn through two pm cellulose ester membranes 1 the front filter to collect any interfering particulate sulfate and sulfite in the air and 2 the back filter treated with KOH to trap SO2 SO2 converted to K2SO on the back filter this filter treated with 10 mL mixture solution of 3 mmol NaHCO and mmol Na2CO3 K2SO dissociates into SO 2 anion which is then detennined by ion chromatography NIOSH Method 6004 1989 recommended flow rate 1 L min sample volume 100 L. Use SO 2 calibration standard to detennine the mass of so a blank analysis perfonned on the media blanks for background correction. Multiply so 2 concentration by the stoichiometric factor to calculate the concentration of SO2. Bicarbonate-carbonate eluant of the back filter may also be oxidized with a drop of 30 . . to SO 2 SO 2 formed measured by ion chromatography to calculate the concentration of so multiply the mass of so 2 found in the analysis multiplied by the stoichiometric factor . Alternatively air drawn through an impinger solution containing V I . . SO2 converted to so I2 which is measured by titration with NaOH or barium perchlorate NIOSH Method S308 1978 . Alternatively aứ drawn though a solid sorbent tube containing molecular sieve 5A SO. adsorbed on this trap desorbed on heating under He purge transported onto GC column and determined by GC MS. Characteristic mass for SO2 is 64. 1997 by CRC Press .