Synergistic adsorption of cationic dyes using montmorillonite/sodium alginate dual-network aerogels: Mechanistic insights and performance evaluation

Abstract

The rapid expansion of light industries has led to a dramatic increase in dye-contaminated wastewater, creating an urgent need for innovative and scalable remediation technologies. In this work, we report a novel two-step in-situ gel-crosslinking strategy for fabricating montmorillonite/sodium alginate (MMT/SA) dual-network aerogels. Homogeneous internal crosslinking was achieved through the controlled reaction between calcium carbonate and glucono-δ-lactone (GDL), effectively overcoming the nonuniform crosslinking gradients commonly observed in conventional calcium-chloride-mediated methods. The engineered composite system integrates the high adsorption capacity of montmorillonite, a natural molecular sieve for dye contaminants, with the dual functionality of SA in three-dimensional network formation and active adsorption participation. The optimized internal crosslinking architecture enables a pronounced synergistic adsorption effect, yielding an aerogel with excellent performance. The material demonstrated a maximum cationic dye adsorption capacity of 383.75 mg/g. Intraparticle diffusion model and thermodynamic analyses collectively confirmed that the adsorption process occurred spontaneously. The bicontinuous network structure facilitates synergistic enhancement through complementary mechanisms of montmorillonite intercalation and alginate coordination while maintaining favorable biosafety characteristics. These findings provide a promising and practically scalable design strategy for developing high-performance adsorbents for industrial wastewater treatment.

Keywords

Montmorillonite / Sodium alginate / Aerogel / Cationic dyes / Methylene blue

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