Functional Surface Tailoring of Chak’o Nanoclay for Efficient Removal of Emerging Contaminants from the Mantaro River: Experimental Insights and Educational Applications in Environmental Science

This study investigated the performance of Chak'o nanoclay after sequential amine functionalization and polymeric (polystyrene sulfonate) coating for the selective removal of pharmaceuticals, pesticides, and heavy metals from water in the Mantaro River in Peru. Batch adsorption experiments were conducted using adsorbent doses of 0.5 to 2.0 g L⁻¹, contact times of 1 to 6 hours, and controlled pH levels. Analytes, including diclofenac and atrazine, were quantified using HPLC, while lead (Pb) and cadmium (Cd) were measured with ICP-MS. Under optimized conditions, the modified nano-clay achieved removal efficiencies of 92.4% for diclofenac, 93.0% for atrazine, and 99.5% for lead. The equilibrium data were best described by the Langmuir Model, indicating monolayer uptake, with maximum adsorption capacities of 45.6 mg g⁻¹ for diclofenac, 48.3 mg g⁻¹ for atrazine, 120.7 mg g⁻¹ for lead, and 104.3 mg g⁻¹ for cadmium. Kinetic fitting favored the pseudo-second-order model, suggesting that the uptake process was controlled by chemisorption. The adsorbent maintained at least 85% of its initial capacity across five regeneration cycles, including an ethanol wash and drying at 60 °C, demonstrating practical reusability. Post-treatment water met food processing standards for turbidity and dissolved solids and showed reduced microbial counts. Overall, surface-modified Chak'o nanoclay provides an effective and sustainable solution for removing co-occurring emerging contaminants and toxic metals from river water, thereby supporting safer water use in agri-food applications in pollution-affected regions.