Oxidation of polystyrene nanoparticles using ozonation under catalytic and non-catalytic conditions

Abstract

Plastic pollution surfaced as a major issue across the globe affecting all compartments of the environment alike. The viciousness of plastics further elevates as they breaks down to form micro and nano sized particles which can easily enter into the body of organisms through water, air and food. These particles persist in the water stream even after conventional waste water and drinking water treatment processes and can easily get accumulate in living organisms including humans. Advanced oxidation processes (AOPs) emerged as an effective strategy for the disintegration leading to even complete mineralisation of many persistant pollutants present in the environment. Various AOP methods like photo-degradation, ozonation, electro-fenton and anodic oxidation are studied for their applicability in degrading synthetic polymer particles also. The present study evaluates the oxidative removal of polystyrene nanoparticles by ozone based oxidation in aqueous medium. Catalytic ozonation was also carried out using TiO2 and V2O5 as catalysts. Particles of 200-400nm size were synthesised by nanoprecipitation technique, suspended in aquadest of variable pH conditions (5, 7 and 9) and subjected to ozonation for 60 minutes. DLS analysis revealed about 75% size reduction of particles upon ozonation. The reduction of organic carbon content in the samples after treatment was evaluated through TOC analysis and highest TOC removal rate of 97.78% was obtained with TiO2 as catalyst at pH 7. TiO2 was an effective catalyst under all pH conditions while catalytic activity of V2O5 found to be increasing with the increase in pH. The results relieved the possibility of using ozonation as a method of nanoplastic remediation from water.