Polycyclic aromatic hydrocarbons (PAHs) adsorption from aqueous solution using chitosan beads modified with thiourea, TiO2 and Fe3O4 nanoparticles

Abstract

In this research paper, Chitosan beads modified with Thiourea, Titanium Dioxide (TiO 2 ) and Magnetite (Fe 3 O 4 ) nanoparticles were prepared for Naphthalene adsorption as a polycyclic aromatic hydrocarbon model. Magnetite and TiO 2 nanoparticles were prepared through co-precipitation and green chemistry method, respectively. Scanning electron microscopy (SEM) coupled to EDX detector allowed to obtain morphological information unmodified and modified beads, in which was observed the main elements introduced by the presence of Thiourea, TiO 2 and Fe 3 O 4 nanoparticles. Magnetization study performed by a vibrating sample magnetometer (VSM) revealed superparamagnetic behavior was observed for Fe 3 O 4 nanoparticles and Thiourea-Magnetite-TiO 2 modified chitosan beads (Cs-T-M-Ti). Also, textural properties were analyzed using BET and BJH methods. Adsorption, isotherms and kinetic studies in a batch system showed a maximum adsorption capacity of 133.690 mg/g for Cs-T-M-Ti beads because Fe 3 O 4 and TiO 2 nanoparticles confer a larger surface and their constituent atoms generate Donor (D)- π -acceptor interactions. Adsorption isotherm was better described using the Freundlich model and Pseudo-second order was the kinetic model that better fitted to experimental data. The high adsorption capacity shown by Cs-T-M-Ti beads allows us to affirm that it is a material with potential application in combined adsorption/(photocatalysis or photo-Fenton) processes for the removal of organic contaminants or heavy metals reduction in industrial wastewater. • Fe 3 O 4 and TiO 2 incorporation in the Chitosan structure improve its textural properties (surface area and porosity). • Thiourea-Fe 3 O 4 -TiO 2 modified chitosan beads showed high affinity to Naphthalene molecule through Donor (D)- π -acceptor interactions. • The proposed nanocomposite represents a promising alternative for potentials applications in combined adsorption/AOPs (photocatalysis or photo-Fenton) processes.