An impurity is to be removed from 20 liters of a pharmaceuticalsolution by contacting it with a batch of adsorbent resin. The adsorption follows a Langmuir type adsorption isotherm where KL = 0.5 g/L and CBmax = 1.5 g/g. The concentration of the impurity in the solution is estimated to be 0.1 g/L. How much adsorbent will be needed to reduce its concentration to 0.01 g/L?