## 3 Results and Discussion
### Fixed-Bed Adsorption
\begin{table}
\begin{tabular}{l c c c c c c c c c c c c} \hline \hline \multicolumn{1}{c}{} & \multicolumn{3}{c}{**Modified Dose Response**} & \multicolumn{3}{c}{**[PERSON]**} & \multicolumn{3}{c}{**[PERSON]**} & \multicolumn{3}{c}{**[PERSON]**} \\ \hline  & **a** & **b** & **Q\({}_{o}\)** & **R\({}^{2}\)** & **K\({}_{a}\)** & **W** & **R\({}^{2}\)** & **K\({}_{t}\)** & **Q\({}_{o}\)** & **R\({}^{2}\)** & **K\({}_{ym}\)** & **t\({}_{50}\)** & **R\({}^{2}\)** \\ \hline Co & 4.49 & 12.15 & 1.69 & _0.994_ & 0.05 & 2.72 & _0.995_ & 0.05 & 1.76 & _0.995_ & 0.18 & 26.52 & _0.992_ \\ Cu & 4.81 & 167.02 & 20.68 & _0.998_ & 0.004 & 35.13 & _0.998_ & 0.004 & 22.77 & _0.998_ & 0.01 & 360.37 & _0.998_ \\ Fe & 6.45 & 17.32 & 2.23 & _0.999_ & 0.05 & 3.50 & _0.997_ & 0.05 & 2.27 & _0.997_ & 0.18 & 36.91 & _0.996_ \\ Mn & 10.29 & 16.18 & 2.10 & _0.999_ & 0.09 & 3.26 & _0.999_ & 0.09 & 2.12 & _0.999_ & 0.28 & 34.22 & _0.998_ \\ Ni & 3.09 & 13.20 & 1.80 & _0.987_ & 0.04 & 2.85 & _0.956_ & 0.04 & 1.84 & _0.956_ & 0.17 & 27.37 & _0.992_ \\ Zn & 7.35 & 15.07 & 1.87 & _0.995_ & 0.07 & 3.05 & _0.999_ & 0.07 & 1.98 & _0.999_ & 0.23 & 31.79 & _0.998_ \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Breakthrough model parameters for MTS9140 at 5 BV/hour flow rate. Figure 6: Breakthrough curves of metals from PLS pumped through MTS9140 at 5 BV/h (pH 1.56). Co = \(\square\), Cu = \(\Diamond\), Fe = \(\Diamond\), Mn = \(\times\), Ni = \(\blacktriangle\), Zn = \(\Diamond\). D noted lines = best-fitting breakthrough model (see Table 3). As was the case for batch pH and sulphate concentration screening, no published data exists studying the fixed-bed adsorption of metals using Puromet MTS9140. Under dynamic operation, MTS9140 displayed the same Cu-selective extraction properties as under previous batch experiments. All other metals present in the PLS reached complete breakthrough within the first 5 BV and exhibited very little overshoot (C\({}_{t}\)/C\({}_{o}\) > 1). The brief period of overshoot observed in Figure 6, which increased slightly as flow rate decreased (Figure 7), indicating that, upon entry to the column, metals were momentarily adsorbed but rapidly displaced as Cu began to load. The fact that all other metals reach complete breakthrough long before Cu indicated that it was not competition for remaining active sites that led to the displacement of metals, but instead that Cu was able to replace metal counter ions immediately upon contact and before resin saturation. All breakthrough models were able to describe metal loading to MTS9140 with a high degree of accuracy (Tables 2-4), with the MDR model generally outperforming other models for Cu. Results of MDR modelling revealed Cu operating capacities of 19.84 mg/g \begin{table}
\begin{tabular}{l c c c c c c c c c c c c c} \hline \hline \multicolumn{1}{c}{} & \multicolumn{3}{c}{**Modified Dose Response**} & \multicolumn{3}{c}{**[PERSON]**} & \multicolumn{3}{c}{**[PERSON]**} & \multicolumn{3}{c}{**[PERSON]**} \\ \hline  & **a** & **b** & **Q\({}_{o}\)** & **R\({}^{2}\)** & **K\({}_{a}\)** & **W** & **R\({}^{2}\)** & **K\({}_{t}\)** & **Q\({}_{o}\)** & **R\({}^{2}\)** & **K\({}_{ym}\)** & **t\({}_{50}\)** & **R\({}^{2}\)** \\ \hline Co & 16.67 & 9.56 & 1.46 & _0.996_ & 0.09 & 2.25 & _0.997_ & 0.09 & 1.46 & _0.997_ & 0.333 & 57.52 & _0.999_ \\ Cu & 9.74 & 206.45 & 32.04 & _0.999_ & 0.002 & 48.75 & _0.997_ & 0.002 & 31.66 & _0.997_ & 0.01 & 1223.9 & _0.997_ \\ Fe & 10.46 & 9.16 & 0.94 & _0.999_ & 0.07 & 1.48 & _0.999_ & 0.07 & 0.96 & _0.999_ & NA & NA & NA & _NA_ \\ Mn & 16.14 & 9.63 & 1.08 & _0.999_ & 0.10 & 1.66 & _0.999_ & 0.10 & 1.08 & _0.999_ & 0.30 & 57.72 & _0.999_ \\ Ni & 16.57 & 9.69 & 1.18 & _0.999_ & 0.09 & 1.81 & _0.999_ & 0.09 & 1.18 & _0.999_ & 0.29 & 57.94 & _0.999_ \\ Zn & 9.97 & 10.25 & 1.13 & _0.996_ & 0.06 & 1.73 & _0.996_ & 0.06 & 1.13 & _0.996_ & 0.17 & 61.52 & _0.996_ \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Breakthrough model parameters for MTS9140 at 2 BV/hour flow rate. at 10 BV/h, 20.68 mg/g at 5 BV/h, and 32.04 mg/g at 2 BV/h.