Green and recyclable PCA nanocomposite hydrogel with superior adsorption capacity for cationic dyes in wastewater treatment

Based on polyacrylic acid (PAA), a novel nanocomposite hydrogel (PCA) was developed by incorporating carboxymethyl cellulose sodium (CMC-Na) and attapulgite (ATP) to synergistically enhance dye adsorption performance. The innovative design leveraged CMC-Na to inhibit ATP aggregation via hydrogen bonding and electrostatic interactions, while improving both dispersion stability and hydrogel hydrophilicity. This modification resulted in a well-defined porous structure, increased specific surface area, enhanced swelling behavior, and superior mechanical integrity. The optimized PCA-4 hydrogel exhibited exceptional adsorption capacities for cationic dyes—486 mg/g for methylene blue (MeB), 442 mg/g for auramine O (AO), 460 mg/g for malachite green (MG), and 450 mg/g for rhodamine B (RB), which significantly outperforming many reported adsorbents. Furthermore, the hydrogel maintained over 80 % removal efficiency after five adsorption-desorption cycles, demonstrating excellent reusability. Its adsorption behavior followed pseudo-first-order kinetics and the Langmuir isotherm model, indicating a physical adsorption-dominated process. This work presents a sustainable, high-performance adsorbent with promising potential for efficient cationic dye removal from wastewater.