(C) (D) (E) (F) Figure 3: Lithium removal efficiency in a fixed-bed column with IRC 747 resin under different flow rates 10 mL.s-1 (A e B), 20 mL.s-1 (C e D) e 30 mL.s-1 (E e F). Source: Authors 3.4. Fixed-bed column performance using IRC748 resin in continuous mode The analysis of the elution profiles for the IRC 748 chelating resin, detailed in Figure 4 (A–F), demonstrates that the hydrodynamics of the fixed-bed system exert a determining influence on the purification kinetics and contaminant removal efficiency. At a flow rate of 10 mL·s⁻¹ (Plots A and B), an initial rapid adsorption stage is observed due to the high availability of active sites in the polymeric matrix. This stage is characterized by a sharp decrease in lithium concentration in the solution, progressing toward a regime where competitive exchange phenomena become predominant. Divalent cations with higher charge density, such as Ca2+, tend to displace monovalent ions like Li+ and Na+, which justifies the temporary oscillations observed until dynamic equilibrium is established. This displacement mechanism can generate temporary fluctuations in the free lithium concentration until adsorption equilibrium is reached (Abusultan et al., 2023). With the increase in flow rate to 20 mL·s⁻¹ (Figure 5 C–D) and 30 mL·s⁻¹ (Figure 5 E–F), a significant change in the kinetic performance of the process occurs. The increased volumetric flow substantially reduces the fluid residence time in the column, limiting effective contact between the solution and the active sites of the resin. This condition imposes restrictions on mass transfer between the liquid and solid phases, favoring early exhaustion of the adsorbent bed and, consequently, reducing the global efficiency of the purification process. 112
RkJQdWJsaXNoZXIy MTM0Mzk2