Question

An ion exchange resin is used to remove nitrate from a water supply with the ionic concentrations found below. The total resin capacity is 1.5 equivalents per liter of resin. a) Do the anions and cations balance? b) What volume of water can be treated with each liter of resin? c) Qualitatively, how would your answer differ if the concentration of CI^- and SO_4^2- were reversed?

Answer 1

Cations meq/L Anions meq/L 2+ 2 SO4 CI NO3 0.0 3.0 1.8 0.8 Nat 2.6 d. Do the anions and cations balance? (1 point) e. What volume of water can be treated with each liter of resin? (2 points) f. Qualitatively, how would your answer differ if the concentrations of Cl and SO were reversed? (1 point) Answer: 2cations4.8 meq/L 2anions4.8 meq/L Charges balance!. b. Each liter of resin can remove 1.5 equivalents. Only chloride is present in quantity and nitrate is well above chloride in ion exchanger preference series shown in lecture, therefore can ignore exchange of ions other than nitrate: Concentration of nitrate 1.8x 10-3 eq/L Volume treated1.5 eq 1.8 x 10-3 eq/L833 liters c. Since SO4 is above NO3 in the preference series, if SO4 were present rather than Cl, SO4 would be adsorbed instead of NO3 There were would be far less, if any, NO3 adsorption. Another resin or much greater amount of resin would be needed.