In a packed absorption column, hydrogen sulphide (H2S) is removed from natural gas by dissolution in an amine solvent. A

[answerhappygod]

In a packed absorption column, hydrogen sulphide (H2S) is
removed from natural gas by dissolution in an amine solvent. At a
given location in the packed column, the mole fraction of H2S in
the bulk of the liquid is 6 × 10−3 , the mole fraction of H2S
in the bulk of the gas is 2 × 10−2 , and the molar flux of H2S
across the gas-liquid interface is 1× 10−5 mol s -1 m-2 . The
system can be considered dilute and is well approximated by the
equilibrium relationship, 𝑦𝐴 ∗ = 5𝑥𝐴 ∗ .
a) Find the overall mass-transfer coefficients based on the
gas-phase, 𝐾𝐺𝐴, and based on the liquid phase, 𝐾𝐿𝐴.
b) It is also known that the ratio of the film mass-transfer
coefficients is 𝑘𝐿𝐴 𝑘𝐺𝐴 = 4. Determine the mole fractions of H2S at
the interface, both in the liquid and in the gas.
c) In another absorption column with a superior packing material
there is a location with the same bulk mole fractions as stated
above. The molar flux has a higher value of 3 × 10−5 mol s -1 m-2 .
The ratio of film mass-transfer coefficients remains, 𝑘𝐿𝐴 𝑘𝐺𝐴 = 4.
The same equilibrium relationship also applies. Explain how you
would expect the overall mass-transfer coefficients and the
interfacial mole fractions to compare to those calculated in parts
a) and b).
d) In the previous parts of this problem you have considered the
thin-film model of diffusion across a gas-liquid interface. Explain
what you would expect to be the ratio of the widths of the
thin-films in the gas and liquid phases for this system if the
diffusion coefficient is 105 times higher in the gas than in the
liquid, but the overall molar concentration is 103 times higher in
the liquid than in the gas.