Kinetics and removal formula of methyl mercaptan by ethanol absorption without neglecting solute accumulation

The wet scrubbing process is commonly adopted for organic odor treatment. In this study, methyl mercaptan (CH₃SH) was selected as a representative hydrophobic organic odorant which was treated using an ethanol solution in a scrubbing tower. Results showed that the ethanol solution can retain the ideal CH₃SH removal effect for 2.0 h. The following experimental conditions were set: intake load of 4,700 m³ m^-2 h^-1, spraying load of 5,100 L m^-2 h^-1, and volume ratio of ethanol/water at 1:5. The solute accumulation of CH₃SH in the scrubbing liquid exceeded 3.01 × 10^-4 kmol CH₃SH/kmol ethanol when the scrubbing tower operated for more than 2.0 h. The mathematical formula which neglected solute accumulation in the ethanol solution exhibited poor adaptability to the removal effect of CH₃SH by ethanol absorption. The CH₃SH removal effect of solute accumulation in the ethanol solution was explored in long-term operation. Meanwhile, the CH₃SH removal rate formula which considered solute accumulation in the ethanol solution could be calculated as η = a'-b'X₂/Y₁. The kinetic parameters of the formula fitting results were phase equilibrium constant m 0.0076, and overall mass transfer coefficient K_Y 4.98 kmol m^-2 h^-1 in the scrubbing tower. These findings can serve as a reference for engineering design and operation for the removal of CH₃SH by ethanol absorption.