Degradation of phenol by perborate in the presence of iron-bearing and carbonaceous materials

Abstract

We investigated the oxidation of phenol by perborate—a newly proposed oxidant—in the presence of iron-bearing and carbonaceous materials through batch experiments. We hypothesized that the oxidation of phenol by perborate was enhanced due to the formation of reactive oxygen species (ROS) in the presence of iron-bearing or carbonaceous materials. Zero-valent iron and ferrous iron (Fe²⁺) promoted the oxidation of phenol by perborate. Biochar, granular activated carbon, an anode carbonaceous material recovered from a spent Li-ion battery, and graphite also accelerated the oxidation of phenol by perborate. Quenching experiments with radical scavengers and electron paramagnetic resonance (EPR) analysis revealed that hydroxyl (˙OH) and superoxide (O₂˙⁻) radicals were generated and enhanced the degradation of phenol in the perborate systems. Singlet oxygen (¹O₂) was involved in the iron-bearing material–perborate systems. Moreover, we found that Persil®, a commercial perborate detergent, enhances the oxidation of phenol in the presence of iron-bearing and carbonaceous materials. Our results suggest that perborate can be used for advanced oxidation processes to remediate recalcitrant organic contaminants in natural environments and engineered systems.