Enhanced heterogeneous activation of peroxymonosulfate by Ruddlesden-Popper-type La2CoO4+δ nanoparticles for bisphenol A degradation

Abstract

Abstract The scalable synthesis of stable catalysts for environmental remediation applications remains challenging. Nonetheless, metal leaching is a serious environmental issue hindering the practical application of transition-metal based catalysts including Co-based catalysts. Herein, for the first time, we describe a facile one-step and scalable synthesis of La2CoO4+δ nanoparticles containing excess oxygen interstitials (+δ) using spray-flame synthesis, and use them as a stable and efficient catalyst for activating peroxymonosulfate (PMS) towards the degradation of bisphenol A. Importantly, the La2CoO4+δ catalyst exhibits higher catalytic degradation of bisphenol A (95% in 20 minutes) and stably than LaCoO3 - x nanoparticles (60%) in the peroxymonosulfate activation system. A high-surface area and high content of Co2+ in the structure showed a strong impact on the catalytic performance of the La2CoO4+δ+PMS system. Despite its high specific surface area, our results showed a very low amount of leached cobalt (less than 0.04 mg/L in 30 minutes), indicating high chemical stability. According to the radical quenching experiments and the electron paramagnetic resonance technology SO4•–, •OH, and 1O2 were generated and SO4•– played a dominant role in bisphenol A degradation. Moreover, the La2CoO4+δ+PMS system maintained conspicuous catalytic performance for the degradation of other organic pollutants including methyl orange, rhodamine B, and methylene blue. Overall, our results showed that we developed a new synthesis method for stable La2CoO4+δ nanoparticles that can be used as a highly active heterogeneous catalyst for PMS-assisted oxidation of organic pollutants.