Microporous adsorbents made of whey protein isolate (WPI) gel were developed and tested as a cation exchanger using copper ions as a challenge material. Isotherms as a function of pH were also determined and described by a modified Langmuir-style isotherm, with values of q(m), K-m, and k(1) of 68mg/g, 1.4 mg/mL and 7.634 x 10(-3) M, respectively.