Engineered composites for water decontamination from heavy metals and emerging pollutants

The scarcity of clean water is a growing global concern, and proper wastewater management is essential to prevent environmental contamination. Conventional treatment methods, such as ultrafiltration, flocculation, coagulation, adsorption, and biological processes, are often limited by high costs and energy demand, incomplete removal of pollutants, and the generation of secondary wastes. This work focuses on the development of innovative, sustainable, and efficient materials for wastewater treatment. Biocompatible and biodegradable sodium alginate-based hydrogels were prepared and added with nanomaterials, including magnetic nanoparticles and graphene oxide-based magnetic nanosheets, to enhance the adsorption capacity for heavy metals. The influence of crosslinker concentration and nanofiller loading on mechanical stability and adsorption efficiency was systematically studied. In parallel, graphitic carbon nitride (g-C3N4) and its heteroatom-doped derivatives (Br, P, and B) were synthesized via co-pyrolysis and post-pyrolysis approaches. Doped g-C3N4 materials were obtained from different precursors, enabling investigation of the effects of chemical structure on photocatalytic activity. The photocatalysts were tested for the degradation of organic dyes (Rhodamine B) and emerging pharmaceutical pollutants (sulfamethoxazole and atenolol), using UV-Vis spectrophotometry and HPLC, showing significant improvement compared to pristine g-C3N4. Overall, the combination of modified alginate hydrogels and heteroatom-doped g-C3N4 provides a versatile, cost-effective, and environmentally friendly approach for the removal of inorganic and organic pollutants from water, demonstrating potential for large-scale water purification and environmental remediation applications.