Insight into the degradation of methomyl in water by peroxymonosulfate. Issue 4 (August 2021)

• Record Type: Journal Article
• Authors: Hayat, Waseem; Zhang, Yongqing; Huang, Shaobin; Hussain, Imtyaz; Huang, Renfeng
• Is Part Of: Journal of environmental chemical engineering. Volume 9:Issue 4(2021)
• Publication Date: 2021-08
• Subjects: Pesticides pollution -- Carbamate pesticide -- PMS oxidation -- Singlet oxygen -- Zero-valent iron; Chemical engineering -- Environmental aspects -- Periodicals; Environmental engineering -- Periodicals; Chemical engineering -- Environmental aspects; Environmental engineering; Periodicals; 660.0286
• DOI: 10.1016/j.jece.2021.105358
• Languages: English
• ISSNs: 2213-2929

Abstract

Abstract: Methomyl (MET) is a carbamate pesticide frequently used in agriculture, globally. Its high solubility makes it a potential water pollutant. MET can be removed by peroxymonosulfate (PMS)-based advanced oxidation processes. This study explains MET degradation by PMS-Only, pyrite (PyR)-PMS and zero-valent iron (ZVI)-PMS systems. The degradation by PMS-Only, PyR-PMS and ZVI-PMS systems was 85.4%, 94.9% and 87.0%, respectively. The generation of reactive oxygen species (ROS) and their role in degradation was elucidated by electron paramagnetic resonance (EPR) and free-radical quenching analyses, respectively. EPR analysis indicated the presence of sulfate (SO4 − ) and hydroxyl ( OH) radicals. The degradation in PMS-Only and ZVI-PMS systems was not significantly inhibited by tert-butyl alcohol (TBA) and methanol (MeOH), which suggests that the degradation in both systems was not majorly carried out by SO4 − and OH. However, furfuryl acid (FFA) resulted in reduced degradation by applied systems, which showed that singlet oxygen ( 1 O2 ) was mainly responsible for degradation in all systems. These results showed that MET was majorly degraded by non-radical PMS oxidation. PMS-Only system resulted in an almost equal degradation, compared with PyR-PMS and ZVI-PMS systems. So, detailed analysis was carried out for PMS-Only system. Hence, experiments were conducted to investigate the effect of PMS concentration, MET concentration, pH and temperature on the degradation by PMS-Only system, which showed that PMS-Only system was efficient from pH 5.0 to pH 9.0, and from 10.0 °C to 40.0 °C. Further, PMS-Only system has a potential for effective degradation in real waters because it resulted in 66.5%, 63.7% and 60.4% degradation in tap water, lake water and sewage water, respectively. Graphical Abstract: ga1 Highlights: Methomyl (MET) was degraded by peroxymonosulfate (PMS)-Only, zero-valent iron (ZVI)-PMS and pyrite (PyR)-PMS systems. Singlet oxygen ( 1 O2 ) played the major role in degradation by applied systems. PyR-PMS system induced degradation by following radical and non-radical mechanisms. PMS-Only system has been more efficient for degradation over pH 5.0–9.0. PMS-Only system induced a good degradation in real water matrices.