Eco-friendly chitosan-gelatin/stone wool-ulexite cryogel for the adsorption of crystal violet, norfloxacin, and bacteria from aqueous media.

The widespread contamination of water by dyes, pharmaceuticals, and pathogenic microorganisms poses a major global challenge, creating an urgent need for efficient and environmentally friendly remediation materials. This study reports a multifunctional hybrid adsorbent composed of chitosan, gelatin, stone wool, and ulexite for the removal of crystal violet and norfloxacin, and the adsorption of two bacterial strains (Escherichia coli and Staphylococcus aureus) from aqueous solutions. The adsorbent was synthesized via a cryogelation process and comprehensively characterized using FTIR, XPS, SEM-EDS, Micro-CT, gas adsorption, AFM, DMA, and cytotoxicity analyses. The results confirmed a uniform elemental distribution, preserved structural integrity, strong mechanical stability, a hybrid porous architecture, and non-cytotoxic behaviour. Response Surface Methodology was employed to identify statistically significant variables and optimize the adsorption process for crystal violet and norfloxacin. The adsorbent has maximum adsorption capacities of 192.7 mg g-1 for crystal violet and 12.8 mg g-1 for norfloxacin, 7.9 × 109 CFU g-1 for E. coli and 1.1 × 1010 CFU g-1 for S. aureus. Adsorption isotherms for crystal violet and norfloxacin were best described by the Langmuir model, indicating monolayer adsorption on a homogeneous surface. Kinetic data followed the pseudo-second-order model, suggesting a surface-controlled rate-limiting step. Thermodynamic analysis revealed that the adsorption process was spontaneous and endothermic. Owing to its high mechanical integrity and reusability, the developed composite is a promising candidate for the adsorption of organic, pharmaceutical, and biological contaminants from water systems.