Activation of peroxymonosulfate by Fe-N complexes embedded within SBA-15 for removal of organic contaminants via production of singlet oxygen

Abstract

Persulfates are recognized as promising oxidants and an alternative to Fenton reaction for water treatment. However, activation methods in hand restrict the practical application. Herein, we explore the possibility of Fe-N complexes being a catalyst for persulfate activation for the first time. The catalyst denoted as Fe-Im-SBA was synthesized from ferric chloride, imidazole, and SBA-15 at high temperature. The internal pore structure of Fe-Im-SBA was maintained well; Fe, N and C elements are evenly distributed on the catalyst. This catalyst presents an extraordinarily catalytic activity for Rh B removal by PMS activation with a removal rate of Rh B that reached up to 97.0% in the first 5 min. It also performed well in a wide pH range with complete removal of Rh B in pH ranged from 0.5 to 10, suggesting the stability of this catalyst in both acidic and alkaline conditions. It also showed high adaptability to degrade different kinds of pollutants, which could give an attractive advantage of Fe-Im-SBA for environmental implications. Through X-ray absorption spectroscopies analysis, it shows that the active sites of Fe-Im-SBA are composed of Fe-N₄ sites and Fe₂–N₂ sites. ¹O₂ were proved to generate in the Fe-Im-SBA/PMS system and serve as the major ROS. Meanwhile, graphitic carbon can accelerate the transfer of electrons, which may also be the reason for its high catalytic performance.