Synthesis and characterization of stabilized oxygen-releasing CaO2 nanoparticles for bioremediation

Bioremediation is one of the general methods to treat pollutants in soil, sediment, and groundwater. However, the low concentration and restricted dispersion of dissolved oxygen (DO) in these areas have limited the efficiency of remediation especially for microorganisms that require oxygen to grow. Calcium peroxide (CaO2) is one of the oxygen-releasing compounds and has been applied to magnify the remediation efficacy of polluting areas. In this study, CaO2 nanoparticles (NPs) were synthesized and evaluated by wet chemistry methods as well as dry and wet grinding processes. The characteristics of CaO2 particles and NPs were analyzed and compared by dynamic light scattering, transmission electron microscopy, scanning electron microscopy, and X-ray powder diffraction. Our results showed that wet-grinded CaO2 NPs had an average particle size of around 110 nm and were more stable compared to other particles from aggregation and sedimentation tests. In addition, we also observed that CaO2 NPs had better DO characteristics and patterns; these NPs generated higher DO levels than their non-grinded form. Accordingly, our results suggested that wet-grinding CaO2 particles to nanoscale could benefit their usage in bioremediation.