Eco-friendly Cadmium Removal Using Novel Modified Clay/Alginate Floatable Beads: A Sustainable Solution for Water Pollution Mitigation

Abstract

Water contamination by heavy metals has become a very alarming issue in all industrialized countries. The present study explores the development of a sustainable and eco-friendly approach to removing cadmium from water sources. A simple method is applied to synthesize floatable beads from a combination of natural clay, alginate, and eco-friendly modifiers, which makes them highly effective at capturing cadmium ions from aqueous solutions. The chemical and physical properties of natural clay (NC) and R-(Clay/Alg@Fe–Ni) composite beads were assessed by several techniques (XRD, BET, FT-IR, SEM, and TGA/DTG). The effects of experimental factors were optimized to maximize the adsorption of Cd (II). Furthermore, the study evaluates the kinetic and equilibrium aspects of cadmium adsorption and assesses the performance of the adsorbents. The results reveal that the adsorption of Cd (II) is most accurately described by the Langmuir and Sips isotherm model and the pseudo-second-order (PSO) kinetic model. These observations imply that the adsorbent's surface exhibits a uniform adsorption behavior, with chemical adsorption primarily governing the adsorption mechanism under optimal conditions. The adsorption capacity (95.7 mg/g) of R-(Clay/Alg@Fe–Ni) is three times greater than that of the unmodified NC, representing an improvement of 64.28%. Inner-sphere complexes involving oxygen-containing functional groups, physical adsorption, ion exchange, and electrostatic interactions were the primary mechanisms for removing Cd (II) ions. Overall, this study indicates that the modified clay/alginate floatable beads exhibit remarkable efficiency in cadmium removal.