3.4.3. Dynamic Adsorption

The fast adsorption process is vividly illustrated in Figure 5a. A piece of pBC-Polym-0.04 was directly immersed into the Cr(VI) solution and it was taken out after 2 s. The liquid was squeezed out that the clean water was obtained. Considering this superior property, the pBC-Polym was filled in a column to achieve flow-through adsorption. The practical image is shown in Figure 5b. Here, 25 mL of Cr(VI) solution was pumped to the column by peristaltic pump to flow through the macroscopic adsorbent with a constant velocity.

In the flow-through adsorption, effect of concentration was examined firstly. The flow velocity was set as 28.4 μL min−1. As shown in Figure 6a, the removal rate was persistently remained at above 96% when Cr(VI) concentration < 100 mg L−1. This indicated the excellent performance of pBC-Polym in dynamic process. Figure 6b revealed the relationship between influent velocity and removal efficiency in dynamic adsorption (*C*<sup>0</sup> = 50 mg L<sup>−</sup>1). The removal rate hardly decreases with the increased flow rate. This sufficiently demonstrated the high mass transfer efficiency of the ions within the body of adsorbent and strongly verified the high prospect of pBC-Polym in wastewater purification. Moreover, the adsorbent exhibited excellent ability in the treatment of diverse metal ions and organic dyes (Supplementary Section S8).

**Figure 5.** (**a**) Illustration on the fast and convenient adsorption by pBC-Polym-0.04, and (**b**) experimental apparatus for dynamic adsorption.

**Figure 6.** Effect of initial Cr(VI) concentration (**a**) and effect of velocity (**b**) on dynamic adsorption by pBC-Polym-0.02, pBC-Polym-0.04 and pBC-Polym-0.08; recycling behavior of the pBC-Polym-0.04 in Cr(VI) adsorption (**c**).
