Synthesis of Hematite Nanodiscs from Natural Laterites and Investigating Their Adsorption Capability of Removing Ni2+ and Cd2+ Ions from Aqueous Solutions

In this work, disc-like hematite (Fe2O3) nanoparticles were prepared using a readily available inexpensive earth material, ferruginous laterite, via a low-cost synthesis route. Prepared hematite nanoparticles were characterized using X-Ray diffraction (XRD), inductively coupled plasma mass spectroscopy (ICP-MS), particle size analyzer (PSA), Fourier transform infrared (FT-IR) spectroscopy, scanning electron microscopy (SEM), and nitrogen adsorption-desorption analyzer. The performance of hematite nanoparticles was evaluated as a heavy metal ion adsorbent. Batch adsorption experiments were conducted to study the adsorption behaviour of Ni2+ and Cd2+ ions as a function of the amount of adsorbent, contact time, and pH. Adsorption data fitted to the linearized Langmuir and Freundlich kinetic models were compared and discussed. The correlation coefficient (R2) was used to determine the best fit kinetic model. Our data fitted the Langmuir kinetic model well and the highest adsorption efficiencies were found to be 62.5 mg/g for Ni2+ and 200 mg/g for Cd2+, respectively. Due to high surface area, pore volume with active sites, and sorption capabilities, hematite nanoparticles can be used as efficient and economical nano-adsorbents for the removal of Ni2+ and Cd2+ ions from industrial wastewater.