Comparative study of biogenic iron oxide nanoparticles from various extracts of Punica granatum and their efficient application for removal of BTEX

Abstract

This study investigated the potential of Punica granatum-mediated iron oxide nanoparticles (FeNPs) in the adsorptive removal of BTEX from wastewater. To gain insight into achieving optimum BTEX removal, the study highlighted the role of phytochemical composition in determining the features of the resulting nanoparticles and, subsequently, the FeNPs' adsorption capacity. It established the Punica granatum part that generates ideal FeNPs with optimum performance in BTEX adsorption. Three Punica granatum parts, the leaves, peels, and seeds, were utilized for the biogenic synthesis of the FeNPs, and the features and performance of the FeNPs in BTEX adsorptive removal were analyzed. It was found that the FeNPs from various Punica granatum parts, namely FeNPs-leaves, FeNPs-peels, and FeNPs-seeds, exhibited distinct features due to the unique phytochemical composition of these parts, as indicated by their total phenolic content (TPC) measurement and GC–MS analysis. The XRD result showed that bio-reduction using the leaves extract yielded magnetite, while bluish-black maghemite and yellowish-brown maghemite were obtained from the peels and seeds extracts, respectively. The three FeNPs also have different specific surface areas, at 8.61 m²/g, 48.45 m²/g, and 35.40 m²/g for FeNPs-leaves, FeNPs-peels, and FeNPs-seeds, respectively. The properties of the FeNPs influenced their BTEX adsorption capacity, with the FeNPs-peels (48.45 m²/g) and FeNPs-seeds (35.40 m²/g) exhibiting higher specific surface area than the FeNPs-leaves (8.61 m²/g), which reflected in the higher BTEX adsorption capacity obtained for the FeNPs-peels and FeNPs-seeds. The BTEX adsorption on the FeNPs mainly occurs through chemisorption in a monolayer surface, as indicated by the adsorption data fitting in pseudo-second-order and the Langmuir isotherm model.

HIGHLIGHTS • Pomegranate leaves, peels, and seeds have different concentration and composition of phytochemicals. • Bio-reduction of FeCl3 using extracts of the three pomegranate parts produced FeNPs with distinct features. • The produced FeNPs exhibited varying tendencies for the adsorptive removal of BTEX in wastewater. • The peels extract yields FeNPs with the highest BTEX adsorption capacity. • The pseudo-second-order and Langmuir isotherm models describe the processes involved in BTEX adsorption.