Ion Exchange Problem

Heavy metals such as copper, cadmium, nickel, lead, and zinc are the most common metals found

in wastewater. At high concentrations, these metals can be toxic and thus the use of synthetic resins

for chelating toxic metal ions in wastewater is considered as a method for their removal. The ion

exchange resin Amberlite IRC$-718$ has an affinity for these heavy metal cations. The sodium ion

on the resin can be used in the exchange of heavy metals. The resin has a total exchange capacity

of $1\mathrm{.}35me\frac{q}{m}L$ with a bulk, wetted density of $225\frac{g}{L}.$

Experimental results from Noureddine et al$.,(2007)$ suggest that after $16$ hours of contacting a $0\mathrm{.}3$

$m\frac{g}{m}L$ solution of $Zn(C_2{H}_3{O}_2{)}_2$ with the resin, the $Z{n}^{2+}$ has an uptake $($q$)$ of $140\mathrm{.}74mgZ\frac{n^{2+}}{g}$

experimental results not denoting this.

a$.$ Write down the ion$-$exchange reaction that occurs when separating zinc from wastewater

by using the Amberlite IRC$-718$ resin.

b$.$ From the provided information, compute the molar selectivity coefficient, $K,$ for $Z{n}^{2+}$ and

compare it to the value estimated from the values taken from Table $15\mathrm{.}5$ below.

Table $15\mathrm{.}5$ Relative Molar Selectivities, $K,$ for Cations with

$8\%$ Cross$-$Linked Strong$-$Acid Resin