Fabrication of Activated Carbon@NiFe-Layered Double Hydroxides/Polyether Sulfone Nanocomposite Beads for the Adsorptive Removal of Trace Cadmium (Cd2+) and Lead (Pb2+) from Wastewater

Abstract

The removal of toxic trace metals such as cadmium (Cd2+) and lead (Pb2+) from wastewater is critical due to their persistence, bioaccumulation, and adverse health effects. In this study, a novel composite adsorbent was synthesized by integrating activated carbon with nickel–iron-layered double hydroxides (NiFe-LDH) and immobilizing the resulting nanocomposite within Polyether sulfone (PES) beads to improve stability, handling, and recyclability. The material was evaluated under varying pH, initial metal concentration, and contact time conditions. The adsorption behavior was investigated using four isotherm models and two kinetic models. The composite beads exhibited maximum adsorption capacities of 1.784 mg g−1 for Cd2+ and 5.882 mg g−1 for Pb2+. The Cd2+ adsorption followed the Langmuir isotherm model (R2 = 0.995), indicating a homogeneous monolayer adsorption, whereas Pb2+ adsorption was best described by the Freundlich model (R2 = 0.955), suggesting heterogeneous surface interactions and multiple binding sites. The kinetic analysis showed that the adsorption of both metals followed a pseudo-second-order model, supporting chemisorption as the dominant rate-controlling mechanism. The AC@NiFe-LDH/PES beads demonstrated high efficiency, structural integrity, and ease of recovery over multiple cycles, highlighting their potential as a sustainable and environmentally friendly adsorbent for trace metal removal from contaminated water.