A novel approach to preparation of nano-adsorbent from agricultural wastes (Saccharum officinarum leaves) and its environmental application

Abstract

Saccharum officinarum leaves (SL) assisted nano-silica (NS) were synthesized and used as adsorbent to remove Pb²⁺ and Zn²⁺ from aqueous solutions. The crystalline nature, functional group, and morphology structure of synthesized NS were characterized by X-ray powder diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), field emission-scanning electron microscopy (FESEM) with EDS mapping, and transmission electron microscopy (TEM). The surface area and charge of the NS were also analyzed by Brunauer-Emmett-Teller (BET) and zeta potential analysis. Removal efficiency of Pb²⁺ and Zn²⁺ from aqueous solutions was carried out under batch mode studies (pH, dose, equilibrium time with initial heavy weight metal ion concentration). The adsorption parameters were determined using pseudo-first-order, pseudo-second-order, Langmuir, and Freundlich models. The kinetics and isotherms data were well fitted with pseudo-second-order and both Langmuir and Freundlich isotherm models. The maximum adsorption capacities for Pb²⁺ and Zn²⁺ onto NS at room temperature (37 °C) were found to be 148 mg/g and 137 mg/g, respectively. Finally, we conclude that the NS synthesized from SL leaves (agricultural waste material) were found to be economically viable, promising adsorbent for metal ions from aqueous solutions and also efficient technology for waste management.

Keywords: Isotherms; Kinetics; Metal removal; Nano-adsorbent; Saccharum officinarum leaves.