3.4. Effect of sample and eluent flow rate
To optimize the sample flow rate, 25 mL solutions of 1 mg L−1
cadmium and copper ions were adjusted to pH of 6.0, and
then passed through the column at flow rates in the range of
1–16 mL min−1 with a peristaltic pump. The column was then
washed with 10 mL of water to remove free metal ions. Subsequently,
5 mL of eluent was passed to desorb the coordinated
cadmium and copper ions from DPC-functionalized SBA-15. The
results in Table 2 demonstrated that sample flow rate variation in the ranges of 1–10 and 1–4 mL min−1 had no effect on the
recovery of cadmium and copper ions on DPC-SBA-15 and DPCSiO2,
respectively. On the other hand, quantitative recoveries for
cadmium and copper ions were obtained at a flow rate range of
0.5–2.0 and 1.0–3.0 mL min−1 for DPC-SBA-15 and DPC-SiO2 with
HCl (2 mol L−1).