Green synthesis of zinc oxide nanoparticles using Eucalyptus leaf extract for effective calcium removal from groundwater

This study explores the challenge of groundwater contamination by calcium ions (Ca2⁺) through the green synthesis of zinc oxide nanoparticles (ZnO NPs) using Eucalyptus leaf extract. This eco-friendly approach offers a sustainable solution compared to traditional chemical treatments. The characterization of the synthesized nanoparticles was performed using X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM). The nanoparticles exhibited an average size of 42 nm and demonstrated a high removal efficiency of 80% for calcium ions with an adsorption capacity of 120 mg/g. XRD analysis confirmed a well-defined crystalline structure, while SEM revealed a uniform distribution of hexagonal and spherical morphologies. FTIR spectra indicated the presence of functional groups that contribute to nanoparticle stabilization. Adsorption experiments conducted at room temperature, within a pH range of 7–8, and a stirring rate of 100 rpm, showed that a weight ratio of ZnO NPs to calcium ions of 1:20 and a contact time of 120 min achieved optimal calcium removal efficiency.