Effective solid–solid and microwave-assisted formation of folic acid@titanium oxide nanoparticles for enhanced batch adsorptive uptake of toxic Cd(II) and Cu(II) pollutants

Abstract

Synthesis of complicated multi-constituent nanocomposites for adsorption, removal and photocatalytic decomposition of miscellaneous pollutants is a tedious process with respect to the cost of synthesis, methodology and characterization of the produced materials. To find out a simple, short, and direct approach for preparation of an efficient nanomaterial from only two components is a challenging target. Therefore, it is aimed in this investigation to design and generate a potential nanosorbent by only combination of folic acid (Fol-Ac) with titanium oxide nanoparticles (TiO2NPs) via simple solid–solid and microwave-assisted formation of a novel Fol-Ac@TiO2NPs nanosorbent in less than 15 min. The assembled nanosorbent was confirmed by determination of the surface coverage using thermal gravimetric analysis 187.4 mg/g (425.6 µmol g−1), homogenous particles distribution with average particle size (56.92–96.74 nm) based on the TEM imaging. The surface was loaded with several effective and related functional groups to Fol-Ac and TiO2NPs as detected from the FT-IR analysis. The characterized Fol-Ac@TiO2NPs was then used as a novel nanosorbent to capture Cd(II) as a highly toxic divalent metal ion and Cu(II) as a moderately toxic ion via batch mode under the contribution of numerous experimental parameters. Zero charge point of Fol-Ac@TiO2NPs was identified at pHPZC = 6.6 to match with the optimum capture at pH 6.0–7.0 for both Cd(II) plus Cu(II) pollutants. Other parameters as reaction time and temperature as well as metal concentration were also performed and modeled to characterize the possible mechanisms via evaluation of the kinetic, thermodynamic and adsorption isotherm investigations, respectively. Fol-Ac@TiO2NPs nanosorbent was efficiently recycled providing 96.67–97.03 % and 91.34–92.47 % stability after the first and fifth cycles, respectively. Moreover, the efficient usage of Fol-Ac@TiO2NPs for uptake of Cd(II) plus Cu(II) pollutants from contaminated water samples was successfully performed providing 98.32–83.97 % and 93.45–83.39 %, respectively.