Exceptional adsorption of different spectral indices of natural organic matter (NOM) by using cerium oxide nanoparticles (CONPs)

In this study, the efficiency of cerium oxide nanoparticles (CONPs) was examined for the adsorptive removal of various spectral indices of Natural Organic Matter (NOM). Two methods, viz. efficient microwave combustion (ECM) and hydroxide mediated approach (HMA), were used to synthesize CONPs. The developed materials were characterized by the field emission scanning electron microscope (FESEM) with energy dispersive X-ray (EDX) and the Fourier transform infrared spectroscopy (FTIR). Moreover, the X-ray powder diffraction (XRD) confirmed the cubic structure with an average crystal size of 20.16 nm (CONP-I) and 6.75 nm (CONP-II). The observed point of zero (pH PZC ) charge was approximately 7.0. The enhanced BET surface area (85.43 m 2 /g, 78.59 m 2 /g) and pore volume (0.007310 cm 3 /g, 0.006761 cm 3 /g) of CONPs support the higher adsorption. The effect of operational parameters (pH, contact time, and adsorbent dosage) and thermodynamical aspects of adsorption was also investigated. The Temkin isotherms described the experimental data better, with a maximum adsorption capacity of 238.9 mg/g (CONP-I) at neutral pH. Further, the experimental data can better be modeled by the pseudo-second-order kinetics (R 2 , 0.9851). Overall, CONPs possess great efficiency for the simultaneous removal of DOC (94%), UV 254 (93%), adsorption slop index (ASI) (95%), phenolic content (88%), and carboxylic content (73%).