Removal of chromium (VI) using spirulina assisted synthesized mesoporous iron oxide nanoparticles

Abstract

Worldwide demand for clean and safe drinking water is a serious concern due to sharply rising industrialization and the growing population. In this work, Spirulina (microalgae) based green synthesis of mesoporous iron oxide nanoparticles (MIONPs) was performed for the adsorption of chromium (VI) in an aqueous solution. Synthesized MIONPs were characterized by XRD, FT-IR, Raman Spectroscopy, Zeta Potential, Particle Size Analyzer, and FESEM with EDX. The mesoporous nature of synthesized material was confirmed using Brunauer–Emmett–Teller (BET) with a pore diameter of 3.837 nm. The adsorption mechanism of Chromium (VI) by synthesized MIONPs was explained using XPS analysis. The various other parameters including pH, Temperature, ion concentration, adsorbent dose, and contact time were also studied in batch experiments for chromium removal. The synthesized material shows the best adsorption efficiency on pH 2, 100 min of contact time, and a temperature of 70 ℃. The Langmuir isotherm model with an adsorption efficiency of 92.8505 mg/g shows better adsorption than the Freundlich isotherm model for synthesized material. The pseudo-second-order model with chemisorption kinetics explains better chromium adsorption with an R2 value of 0.99863 than the pseudo-first-order model. Regeneration studies analyse the recyclable use of green synthesized MIONPs during the adsorption of chromium. This study could be useful for the removal of multiple heavy metals at a time from drinking water safely without harming the ecosystem and hence it is employable to meet the sustainability goals.