Effective removal of Cu(II) from water by three-dimensional composite microspheres based on chitosan/sodium...

Chitosan (CS) is commonly used as an adsorbent for removing Cu(II) from water, but it has drawbacks such as solubility in dilute acid, difficulty in recycling in powder form, and short service life. This study utilized sodium alginate (SA) as a gel carrier to encapsulate CS, combined with silicon dioxide (SiO₂) to improve mechanical stability. The preparation of CS/SA/SiO₂ (SSC_1.0) involved physical blending, CaCl₂ cross-linking, and freeze-drying. Characterization methods such as SEM-EDS, FTIR, BET, and XRD were used to analyze the structural composition of SSC_1.0. The material exhibited a folded surface, porous internal cross-section, nitrogen/oxygen-containing functional groups, and thermal stability in high temperatures and various aqueous environments. The adsorption performance of SSC_1.0 on Cu(II) was evaluated under different conditions, showing a maximum adsorption capacity of 47.50 mg/g. The material maintained a removal rate above 70 % after 5 cycles. SSC_1.0 also showed the highest removal rate of Cu(II) when applied to mine wastewater treatment. Adsorption modeling indicated that the process was driven by chemical reactions and was spontaneous and heat-absorbing.'