Nitrophenylfurfural grafted amino functionalized silica nanoparticles for adsorptive removal of tartrazine dye from water

In the present study, the synthesis of novel nitrophenylfurfural grafted silica nanoparticles (NPF-SiNPs) having multifunctional properties is reported. Using a sol-gel process, the silica nanoparticles were functionalized with amino groups to develop amino functionalized silica nanoparticles (AFSi-NPs). Nitrophenylfurfural derivatives (para, ortho, and meta) were further grafted onto the AFSi-NP surface to prepare the NPF-SiNPs using a post-grafting approach. X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, transmission electron microscopy (TEM), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), and Brunauer-Emmett-Teller (BET) analysis were used for characterization of obtained AFSi-NPs and NPF-SiNPs. The FTIR and XRD results revealed the presence of furfural derivatives on the silica surface and BET analysis revealed a remarkable surface area of 80 m2 g-1 for NPF-SiNPs especially when p-nitrophenylfurfural was used for modification of AFSi-NPs. TEM/SEM images depicted the spherical mesoporous morphology of as-prepared NPF-SiNPs having a size of 700-800 nm. The material (NPF-SiNPs) was then effectively applied for the adsorptive removal of tartrazine (TTZ) dye from wastewater. Out of the three adsorbents (p-NPF-SiNPs, o-NPF-SiNPs, and m-NPF-SiNPs), the p-NPF-SiNPs showed higher activity towards TTZ removal. The influence of well-established adsorption parameters, including pH, p-NPF-SiNP amount, temperature, TTZ concentration, and contact time, was studied. Langmuir and Freundlich adsorption isotherm models were applied to simulate the equilibrium data. The equilibrium sorption data were better matched to the Langmuir isotherm model, as evidenced by the higher values of r2 (nearly 1), which indicated the presence of an adsorption monolayer of TTZ on the surface of p-NPF-SiNPs. The maximum Langmuir adsorption capacity was found to be 203.5 mg g-1 at 323 K. The adsorption kinetic data for adsorption of TTZ onto p-NPF-SiNPs were correlated well with the pseudo-2nd (PS)-order model. In addition, TTZ adsorption onto p-NPF-SiNPs was investigated on the molecular level using Monte Carlo and molecular dynamics simulations. Synthesis of novel nitrophenylfurfural grafted silica nanoparticles (NPF-SiNPs) having multifunctional properties is reported for removal of tartrazine dye.