Fabrication of Silver-Incorporated Zn-Al Layered Double Hydroxide: Characterization and Bromide-Adsorption Performance

In this study, a novel adsorbent was developed by synthesizing Zn-Al layered double hydroxide (LDH) incorporated with silver nanoparticles (Ag-NPs), and its effectiveness in bromide removal from aqueous solutions was systematically evaluated. The X-ray Diffraction (XRD) and Fourier Transform Infrared Spectroscopy (FTIR) analyses confirmed the integration of Ag-NPs within the LDH, ensuring uniform chemical composition and structural integrity. A series of controlled batch trials, each varying a single parameter (adsorbent dose, contact time, or temperature) confirmed that over 95% of bromide (initially 5320 μg/L) was removed under optimized conditions. LDH/Ag-NPs exhibited superior performance, with kinetics well described by a second-order reaction model. Thermodynamic analysis confirmed the spontaneous and exothermic nature of bromide adsorption, with ΔG° values ranging from −2.03 to −0.73 kJ/mol as the temperature increased from 22 °C to 52 °C. In continuous-flow experiments, packed-bed column tests illustrated that LDH/Ag-NPs maintained more effective bromide removal than LDH alone over extended periods. Conductivity measurements further supported this enhancement, with LDH/Ag-NPs reducing final conductivity to 139 µS/cm, compared to 212 µS/cm for LDH. Furthermore, this study revealed the notable antimicrobial activity of LDH/Ag-NPs, as evidenced by a significant reduction in bacterial growth compared to LDH alone, highlighting its dual functionality for both bromide adsorption and water disinfection. Overall, the incorporation of Ag-NPs into LDH offers a promising strategy for developing multifunctional and sustainable water treatment systems.