Comparative Evaluation of Biosynthesized Nanoscale Zerovalent Iron and Iron-Oxide Nanoparticles in Mercury Adsorption

Abstract

An environmentally friendly approach was adopted in the synthesis of nanoscale zerovalent iron (NZVI) and iron oxide nanoparticles (Fe2O3). Plant extracts from aloe vera and myrtle were used as reducing agents for the synthesis of NZVI. Physical and chemical properties of the biosynthesized nanoparticles were characterized. The adsorption properties of the biosynthesized nanoparticles were evaluated by batch adsorption at varying conditions of pH, initial concentration, contact time, agitation speed, and adsorbent dosage. NZVI (81.9%) demonstrated the highest removal efficiency at pH 7 compared to Fe2O3 (77.5%). The experimental results fit the Langmuir model with a correlation efficiency of 0.973 and 0.992 for NZVI and Fe2O3, respectively. NZVI showed higher maximum adsorption capacity compared to Fe2O3. The results obtained for both adsorbents also fit to pseudo-second-order kinetics, suggesting that the adsorption of mercury to both adsorbents is a physical, monolayer, and homogeneous process.