Q$1)$ Your company has been using a polyamide$-$based commercial reverse osmosis $($RO$)$

membrane to separate salt from water.

The properties of this RO membrane are as follows:

Pure water permeability: $1\frac{L}{m^2}.$h$.$bar and NaCl rejection: $99\%.$

A new customer wants to sell a new cellulose$-$acetate$-$based RO membrane. They claim that the

performance of this membrane is better than the polyamide$-$based RO membrane. Here is the data

provided by the customer for the new RO membrane.

This membrane reduces $12$kgNaC$\frac{l}{m^3}$ in the feed solution to $0\mathrm{.}468$kgNaC$\frac{l}{m^3}$ in the product

solution. By applying the pressure difference of $56$atm, the permeate flow rate was measured as

$3\mathrm{.}84{10}^{-8}\frac{m^3}{sec}.$ The area of the membrane used for these measurements is $4{10}^{-3}{m}^2.$ The

osmotic pressures of the NaCl solution on the feed and permeate side are $10$atm and $0\mathrm{.}4$atm,

respectively.

Evaluate if the cellulose acetate membrane performs better than the polyamide RO membrane.

Hint: Compare the pure water permeability and NaCl rejection of two membranes to evaluate the

customer's claim about the new membrane.