-1 3.18 Perchlorate (C104) is an anion that can contaminate drinking water sources, but it can be removed from water using membrane bioreactors. (a) Calculate the diffusion constants of perchlorate anions in water at 20C. (b) A membrane is being used in tests that is 0.2 m in total cross-sectional area and 225 um in thickness. Assuming diffusion occurs only through the available surface area (70% of the total), and that a perchlorate concentration on the other side is maintained at zero, at a perchlorate concentration of 100 mg L- what is (i) the effective diffusion constant and (ii) the chemical flux through the membrane? (c) An instantaneous perchlorate flux of 0.038 ug cm ?s' was measured across the membrane in tests. (i) What is the diffusion constant based on these tests? (ii) is the ratio of this actual diffusion constant to the one estimated in part b due to the area reduction? (iii) What does this suggest about the effect of the membrane on chemical diffusivity