Eco-friendly cerium oxide nanoparticles: A promising solution for Congo red dye removal from water

• CeO 2 NPs were synthesized by leaf extract from Toxicodendron radicans with CeCl 3 salt • Green synthesized CeO 2 NPs were used for the adsorption of Congo red dye in water • CeO 2 NPs characterized by TGA, XRD, FTIR, SEM, BET, Zeta sizer, PZC, & Zeta potential • CeO 2 NPs (0.25 g) removed 91% of Congo red dye (40 ppm) at pH 4, and temp. 313K in 2h • Adsorption was chemical & spontaneous, with chemisorption as the rate-determining step Several health issues have been linked to the release of Congo red dye into water resources from textile industries. In this regard, the present study investigated the removal of the Congo red dye from water using green-synthesized cerium oxide nanoparticles (CeO 2 NPs). These NPs were synthesized through a novel green approach, by using CeCl 3 salt and leaf extract from Toxicodendron radicans . The successful synthesis of cerium oxide CeO 2 NPs was confirmed by morphological characterization. Under optimal conditions of pH 2, 0.25 g of adsorbent, 40 ppm of initial dye concentration, 313K temperature, and 120 minutes of contact time, the CeO 2 NPs demonstrated impressive performance, eliminating 91% of the Congo red dye. The adsorption mechanism aligned with a pseudo-second-order kinetic model, suggesting dye attachment to the adsorbent surface. The experimental findings showed a strong correlation with various isotherm models, including non-linear Dubinin and Langmuir forms, as well as both linear and non-linear Temkin and Freundlich forms. Mechanism of adsorption was found to be chemisorption with maximum adsorption efficiency (q max ) of 120.8 mg g -1 . Kinetic and thermodynamic evaluations revealed that the adsorption process was both chemical in nature and occurred spontaneously, with chemisorption identified as the limiting factor in the reaction rate. Elovich kinetic model shows an initial adsorption rate of 17 mg g -1 min -1 , which confirms favourable adsorption with chemisorption mode. Based on these results, it is concluded that the green-synthesized CeO 2 NPs are an effective amendment for the maximum removal of Congo red dye from contaminated water.