Co2+ ion exchange, at room temperature, from aqueous cobalt - sodium c
hloride solutions with NaY zeolite has been studied. The effect of con
tact time on the shape of the sorption curves of Co2+ using zeolite Y
dehydrated at 600 degrees C is similar to the one found in our previou
s work with a zeolite dehydrated at 150 degrees C. A fast sorption upt
ake is observed in which 1.8 meq of Na+ ions/g of zeolite are replaced
by cobalt ions followed by a desorption process where the uptake decr
eases to 1.2 meq/g zeolite. The Co2+ sorption using zeolite Y dehydrat
ed at 600 degrees C is increased when ethylenediamine solution is pass
ed through the zeolite. The Co2+ sorption uptake, initially 2.0 meq/g,
increases to 2.8 meq/g of zeolite. This behavior is explained by the
location and coordination of cobalt in zeolite Y sites. It is suggeste
d that the highest uptake process is due to the blocking of zeolite si
tes by a Co complex compound.