Synthesis of clay-based Laponite/sodium alginate composite hydrogel beads for efficient removal of methylene blue and...

The presence of heavy metals and dyes in water poses serious threats to the ecological environment and human health. Conventional powder adsorbents are significantly limited in practical applications due to their difficult separation characteristics. Therefore, the development of practical adsorbents that integrate high adsorption capacity, monolithic form, and environmental sustainability is of great importance. In this study, we fabricated novel monolithic composite gel beads (SA/Lap) by ionically crosslinking the natural polymer sodium alginate (SA) with high-purity synthetic Laponite clay prepared in our laboratory. This synthetic strategy avoids the complex purification processes and secondary pollution issues associated with natural clay modifications. The resulting SA/Lap beads combine the monolithic morphology of the hydrogel with the adsorption capability of Laponite, enabling efficient removal of dyes and heavy metal ions from water. Systematic adsorption studies using methylene blue (MB) and Cu(II) as model pollutants demonstrated that the optimal composite exhibited exceptional adsorption performance, with maximum adsorption capacities reaching 1375.29 mg/g for MB and 97.04 mg/g for Cu(II). The adsorption kinetics followed a pseudo-first-order model. Crucially, the SA/Lap beads demonstrated outstanding performance in fixed-bed column tests and cyclic adsorption experiments, maintaining high adsorption capacity and structural integrity even under high flow rate conditions, underscoring their excellent reusability and potential for continuous-flow industrial applications. This study provides a valuable strategy for designing high-performance, environmentally friendly, and economically viable adsorbents through the synergistic combination of synthetic clay minerals with biopolymers.