Construction and elucidation of zerovalent iron@terephthalic acid/iron oxide catalyst to activate peroxymonosulfate for accelerating and long-lasting NOx removal

Abstract

Recently peroxymonosulfate (PMS)-based advanced oxidation techniques (AOTs) have been widely used nowadays for pollutant removal. However, Fenton/Fenton-like reactions using Fe-based catalysts are highly promising for the NOx treatment due to their improved catalytic efficiency, low cost, and offering effectual reactive oxygen species (ROS). However, the long-term reusability without generating (Fe) sludge and its inactivation due to the non-spontaneous conversion of Fe(II)/Fe(III) are problematic. Hence, a variety of catalysts had been employed to activate Fe(II) and for efficient ROS generation. In this work, we designed a single metal-based stable and heterogeneous Fenton-like technology (SMHFT) with Fe3O4 (base material) functionalized using 2-amino terephthalic acid (ATA) to increase stability and surface area. The Fe3O4@ATA composite was finally decorated using solid zero-valent-iron (Fe0) (i.e., MTAFe0), where terminal Fe0 offers an active surface for ultrafast PMS activation and efficient ROS generation. The ROS containing SO4-•, HO•, and 1O2 entities are entirely used for NO oxidation with better mass transfer without using an electron (e-) mediator and restored Fe-efficiency. The electron paramagnetic resonance (EPR) and various scavengers verified the ROS participating in NO oxidation significantly, as well as in-situ regeneration of the catalyst. The synthesized MTAFe0 showed ∼ 94 % efficiency, and the density functional theory (DFT) elucidated PMS adsorption and its ultrafast activation by ROS generation. Finally, the reusability of MTAFe0 was investigated, and it showed over 90% efficiency after 10-continuous cycles. Hence, the developed SMHFT system has great potential for fast NO removal with long-term utilization, which is promising and could be implemented sustainability for air pollution treatment.