Ozonization of water can be used to control odor and for disinfection.

In the simple ozonizer sketched in Fig. P.8.1, air containing 5.0 mol % O₃ is bubbled through water at 20°C flowing at the rate of 100 kg/min. The absolute pressure in the ozonizer is 1.2 atm. The solubility of pure O₃ gas in water at 1 atm and 20°C is 0.57 g/L.

(a) What is the maximum concentration of O₃ in water that can be obtained for these conditions?

Express your result in g/L and as a mole fraction.

(b) In the actual operation, the mole fraction of O₃ in the ozonated water is 4.5 × 10⁻⁶ while the mole fraction of O₃ in the air leaving the ozonizer is 0.02. Determine the molar (mol/min) and volumetric (m3/min) flow rate of the feed air and the rate of mass transfer of O₃.

(c) Assume that the air bubbles in the ozonizer occupy a volume of 0.3 m³ and that they are, on overage, 2 mm in diameter.

Determine the mass transfer flux of O₃ at the bubble–water interface.

FIGURE P.8.1:

Transcribed Image Text:

Feed water 100 kg/min Feed air 0.05 mol O3/mol Pi Outlet air Ozonated water