Zero-Valent Copper-Mediated Peroxymonosulfate Activation for Efficient Degradation of Azo Dye Orange G

Contribution of 1O2 in the efficient degradation of organic pollutants with Cu0/Cu2O/CuO@N-C activated peroxymonosulfate: A Case study with tetracycline

Peroxymonosulfate-mediated advanced oxidation processes (PMS-AOPs) degrading organic pollutants (Tetracycline (TC) as an example) in water with singlet oxygen (1O2) as the main reactive oxygen has received more and more attention. However, the generation mechanism of 1O2 is still unclear. Consequently, this study investigates the 1O2 formation mechanism during the activated PMS process using a nitrogen-copper-loaded carbon-based material (Cu0/Cu2O/CuO@N-C), synthesized by thermally decomposing organobase-modified HKUST-1 via a one-pot method. It was discovered that incorporating an organobase (Benzylamine) into the metal organic framework (MOF) precursor directs the MOF's self-assembly process and supplements its nitrogen content. This modification modulates the Nx-Cu-Oy active site formation in the material, selectively producing 1O2. Additionally, 1O2 was identified as the dominant reactive oxygen species in the Cu0/Cu2O/CuO@N-C-PMS system, contributing to TC degradation with a rate of 70.82%. The TC degradation efficiency remained high in the pH range of 3-11 and sustained its efficacy after five consecutive uses. Finally, based on the intermediates of TC degradation, three possible degradation pathways were postulated, and a reduction in the ecotoxicity of the degradation products was predicted. This work presents a novel and general strategy for constructing nitrogen-copper-loaded carbon-based materials for use in PMS-AOPs.

Textile dye removal in wastewater by peroxymonosulfate (PMS) activation on a zero-valent iron nanoparticle-modified ultrafiltration catalytic membrane (nZVI@PES)

The use of the nano zero-valent iron (nZVI) nanoparticle-based advanced oxidation systems in conjunction with an activator such as peroxymonosulfate (PMS) to generate hydroxyl and sulfate radicals for the degradation of organic pollutants has been extensively used in recent studies. In this study, a nZVI-modified polyethersulfone (PES) membrane (nZVI@PES) was produced successfully by attaching the nZVI catalytic nanoparticles on the surface of a commercial microporous polymeric membrane material using a simple and easy filter press coating method. The presence of nZVI nanoparticles on the nZVI@PES membrane was confirmed by XRD, SEM, and EDS analyses. The nZVI@PES membrane was applied in the dead-end filtration system in the presence of the PMS activator to treat the reactive black 5 (RB5) dye solution. The effect of catalyst loading, RB5 dye concentration, PMS dosage, and pH level on the nZVI@PES membrane/PMS system was investigated. Quenching experiments were carried out to identify the reactive species responsible, and reusability tests were conducted on the membrane. The highest decolorization efficiency (96.8%) was obtained at 20 mg/L RB5 dye solution, initial pH of 3, the nZVI loading of 5 mg/cm2, and the PMS dosage of 300 mg/L at the end of a reaction time of 30 min. The formation of HO•, [Formula: see text], [Formula: see text] and, 1O2 was confirmed by quenching experiments. The results indicate that the nZVI@PES membrane/PMS system could successfully treat wastewater contaminated with an organic dye.

Accelerated Removal of Acid Orange 7 by Natural Iron Ore Activated Peroxymonosulfate System with Hydroxylamine for Promoting Fe(III)/Fe(II) Cycle

In this study, peroxymonosulfate (PMS) was activated by cheap and readily available natural iron ore to remove Acid Orange 7 (AO7) in water with the assistance of hydroxylamine (HA). Results show that the presence of HA could accelerate the Fe(II)/Fe(III) cycle on the ore surface, promoting the activation of PMS to generate reactive oxidative species. The effects of ore dosage, PMS dosage, HA dosage and initial pH on the degradation of AO7 were investigated in the HA/Ore/PMS system. Under the optimal conditions, the removal of AO7 could reach 93.1% during 30 min, which was 41.4% higher than the ore/PMS system. The AO7 removal increased with the increase of HA, PMS and ore dosage, but was unaffected by the initial solution pH. Based on radical scavenging experiments and EPR tests, the dominant reactive species in the HA/Ore/PMS system were revealed to be the sulfate radical (SO4•−), singlet oxygen (1O2), superoxide radical (O2•−) and hydroxyl radical (•OH), which were responsible for the AO7 degradation. Furthermore, the possible reaction mechanism of PMS activation was proposed. This study provides an efficient technique for the removal of azo dye organic contaminant in water, which has great practical significance.