Estimation of the Overall Mass Transfer Coefficient

Using the two-film mass transfer theory, calculate the overall air-water mass transfer coefficient of MCF and BF a) in a laboratory tank for a wind speed of 0.5 m/s measured 10 cm above the water surface, and b) at the surface of a lake for a wind speed of 15 m/s measured 3 m above the water. Assume an ambient (air and water) temperature of 25C, a system specific factor () of 0.5 in water and 0.67 in air, and a unit surface area.

Table 1: Physical/chemical Properties of MCF and BF Property MCF BF Name 1,1,1-trichloroethane tribromomethane Formula C2H3C13 CHBr3 MW, g/mol 133.4 252.8 T, C 74.1 149.5 Tm, C -30.4 8.3 KH, atmL/mol (25 C) 19.5 0.60 Table 2: Environmental Data for Problem 1 Parameter MCF BF Air Conc., Ca, ng/l 0.93 0.05 Surf. Water Conc., Cw, ng/l 2.5 9.8 (at depth 0-10 m) Deepwater Conc., Cw, ng/l 1.6 3.0 (at depth 200 m) KH, seawater, atm-L/mol 6.5 (0 C) 0.20 (0 C) 23.8 (25 C) 0.86 (25 C)