Nickel adsorption from aqueous solution using lemon peel biomass chemically modified with TiO2 nanoparticles

Adsorption technique has attracted considerable attention as a promising alternative for reducing heavy metal ions in water sources. This work is focused on the adsorption of nickel ions using lemon peel biomass chemically modified with titanium dioxide (TiO₂) nanoparticles through siloxane bonds. The biomass was characterized by FT-IR and compositional analyses to identify functional groups and elemental composition. From these measurements, it was observed peaks at 1741, 1328, and 1229 cm^?1, characteristics of CO, C–O, and C–H stretching bands, respectively. These organic bonds can be related to the existence of cellulose, lignin, and pectin biopolymers, which are present in the lemon peel biomass, as observed from the compositional analyses. After grafting TiO₂ nanoparticles onto lemon peel biomass surface, it was observed from FTIR the presence of vibrational bands at 1524, 1054, and 943 cm^?1, characteristics of –Ti-O-C, –Si-O-Si, and –Ti-O-Si functional groups. Additionally, the morphology and elemental composition of the lemon peel biomass modified with the titanium dioxide (TiO₂) nanoparticles were determined by SEM microscope, observing the presence of C, O, Ti, and Si atoms from the EDS mapping. Batch adsorption experiments were carried out to determine the effect of pH and biomass particle size on adsorption of Ni (II) ions from aqueous solution. From these experiments, maximum adsorption of Ni (II) ions of 78 ± 0.2% was obtained at pH 6.0, while no significant effects were observed for biomass particle size. Furthermore, the modification of biomass with TiO₂ nanoparticles increased up to 90 ± 0.1% the Ni (II) ions adsorption, suggesting the potential of the biomass modified with metal oxide nanoparticles for removal of heavy metal ions.