Bimetallic metal-organic framework as a high-performance peracetic acid activator for sulfamethoxazole degradation

Amino-functionalized MIL-101(Fe)-NH2 as efficient peracetic acid activator for selective contaminant degradation: Unraveling the role of electron-donating ligands in Fe(IV) generation

Peracetic acid-based advanced oxidation processes (PAA-AOPs), which generate various reactive radicals, have garnered substantial attention for degradation emerging contaminants (ECs). However, nonselective radical-based PAA-AOPs often suffer from interference by water matrix components, causing low contaminants removal efficiency. This study explores the use of amino-(NH2)-functionalized metal-organic frameworks (MIL-101(Fe)-NH2) as heterogeneous catalysts for PAA activation, enabling the generation of high-valent iron- (Fe)-oxo species (Fe(IV)) capable of efficiently degrading ECs (80 -100 %, within 30 min). The Fe(II) clusters in MIL-101(Fe)-NH2, modulated by electron-donating -NH2 groups, play a pivotal role in Fe(IV) generation. Scavenger and probe experiments confirmed Fe(IV) as the primary reactive species responsible for ECs degradation. Density functional theory calculations demonstrated that the four-electron transfer to generate Fe(IV) has lower free energy than the two-electron transfer to generate organic radicals (e.g., CH3COO• and CH3C(O)OO•). Furthermore, thermodynamically unfavorable CH3COO• desorption further promotes Fe(IV) generation. The PAA/MIL-101(Fe)-NH2 system efficiently degraded SMX (kapp= 121.2 -287.2 M-1s-1) and other ECs (kapp= 40 -432 M-1s-1) with minimal interference from water matrix components and excellent reusability. This study demonstrates that MIL-101(Fe)-NH2 is a robust catalyst for PAA activation and provides a novel approach for selectively generating Fe(IV) for ECs degradation.

Enhanced Mn(II)/peracetic acid by nitrilotriacetic acid to degrade organic contaminants: Role of Mn(V) and organic radicals

In this work, it was found that the presence of nitrilotriacetic acid (NTA) could enhance the elimination of sulfamethoxazole (SMX) significantly in Mn(II)/peracetic acid (PAA) process. NTA firstly complexed with Mn(II) to produce Mn(II)-NTA complex, which could activate PAA producing CH3C(O)O· and Mn(III)-NTA complex. Subsequently, Mn(V) was generated via two-electron transfer between Mn(III)-NTA complex and PAA. According to the results of UV-vis spectrum analysis, scavenging experiments and chemical probe method, organic radicals and Mn(V) were proved to participate in SMX abatement and Mn(V) was the predominant reactive oxidant. Four possible degradation pathways of SMX in Mn(II)/PAA/NTA process including hydroxylation, amino oxidation, bond cleavage and coupling reaction were proposed based on six identified degradation products. Mn(II)/PAA/NTA process worked only in acidic and neutral conditions and the increase in PAA, Mn(II) or NTA concentration could accelerate SMX removal. This study provides a strategy for improving PAA activation by Mn(II) and an insight into SMX degradation mechanism by Mn(II)/PAA/NTA process.

Revealing the vital role of sulfur site on the surface of pyrite in 1O2 formation for promoting ciprofloxacin degradation via peracetic acid activation

Pyrite has been widely utilized to activate oxidants for water treatment, yet the regulation of reactive oxygen species (ROS) by sulfur sites on its surface has been overlooked. In this study, the surface sulfur sites were regulated by thermal modification of natural pyrite in the N2 atmosphere (denoted as P-X, where X represented pyrolysis temperatures ranging from 400 to 700 °C), and these modified pyrites were employed to activate peracetic acid (PAA) for ciprofloxacin (CIP) degradation. The results revealed that the degradation rate of CIP increased as the reduced sulfur content increased, with the P600/PAA system achieving the highest apparent degradation rate (kobs = 0.0999 min-1). Quenching experiments and electron paramagnetic resonance (EPR) analysis identified various ROS involved in the P-X/PAA system, with hydroxyl radical (·OH) and singlet oxygen (1O2) identified as dominant reactive species responsible for CIP degradation. The reduced sulfur sites served as the primary active sites facilitating the conversion of organic radicals (·CH3C(O)OO) into superoxide radicals (·O2-) and 1O2. Furthermore, the P600/PAA system demonstrated robust adaptability under both acidic and neutral pH conditions, efficiently degrading CIP even in the presence of complex matrices such as Cl-, NO3-, SO42-, NH4+, or humic acid (HA) in water bodies, although HCO3- was found to inhibit CIP degradation. This study significantly enhances our understanding of the interaction between reduced sulfur sites and ROS in PAA-based advanced oxidation processes (AOPs), offering a promising technology for efficient antibiotic treatment in water purification.

From wastewater to clean water: Recent advances on the removal of metronidazole, ciprofloxacin, and sulfamethoxazole antibiotics from water through adsorption and advanced oxidation processes (AOPs)

Antibiotics released into water sources pose significant risks to both human health and the environment. This comprehensive review meticulously examines the ecotoxicological impacts of three prevalent antibiotics-ciprofloxacin, metronidazole, and sulfamethoxazole-on the ecosystems. Within this framework, our primary focus revolves around the key remediation technologies: adsorption and advanced oxidation processes (AOPs). In this context, an array of adsorbents is explored, spanning diverse classes such as biomass-derived biosorbents, graphene-based adsorbents, MXene-based adsorbents, silica gels, carbon nanotubes, carbon-based adsorbents, metal-organic frameworks (MOFs), carbon nanofibers, biochar, metal oxides, and nanocomposites. On the flip side, the review meticulously examines the main AOPs widely employed in water treatment. This includes a thorough analysis of ozonation (O3), the photo-Fenton process, UV/hydrogen peroxide (UV/H2O2), TiO2 photocatalysis, ozone/UV (O3/UV), radiation-induced AOPs, and sonolysis. Furthermore, the review provides in-depth insights into equilibrium isotherm and kinetic models as well as prospects and challenges inherent in these cutting-edge processes. By doing so, this review aims to empower readers with a profound understanding, enabling them to determine research gaps and pioneer innovative treatment methodologies for water contaminated with antibiotics.

Unlocking the power of activated carbon-mediated peracetic acid activation for efficient antibiotics abatement in groundwater: Coupling the processes of electron transfer, radical production, and adsorption

The activation of peracetic acid (PAA) by activated carbon (AC) is a promising approach for reducing micropollutants in groundwater. However, to harness the PAA/AC system's potential and achieve sustainable and low-impact groundwater remediation, it is crucial to quantify the individual contributions of active species. In this study, we developed a combined degradation kinetic and adsorption mass transfer model to elucidate the roles of free radicals, electron transfer processes (ETP), and adsorption on the degradation of antibiotics by PAA in groundwater. Our findings reveal that ETP predominantly facilitated the activation of PAA by modified activated carbon (AC600), contributing to ∼61% of the overall degradation of sulfamethoxazole (SMX). The carbonyl group (CO) on the surface of AC600 was identified as a probable site for the ETP. Free radicals contributed to ∼39% of the degradation, while adsorption was negligible. Thermodynamic and activation energy analyses indicate that the degradation of SMX within the PAA/AC600 system requires a relatively low energy input (27.66 kJ/mol), which is within the lower range of various heterogeneous Fenton-like reactions, thus making it easily achievable. These novel insights enhance our understanding of the AC600-mediated PAA activation mechanism and lay the groundwork for developing efficient and sustainable technologies for mitigating groundwater pollution. ENVIRONMENTAL IMPLICATION: The antibiotics in groundwater raises alarming environmental concerns. As groundwater serves as a primary source of drinking water for nearly half the global population, the development of eco-friendly technologies for antibiotic-contaminated groundwater remediation becomes imperative. The innovative PAA/AC600 system demonstrates significant efficacy in degrading micropollutants, particularly sulfonamide antibiotics. By integrating degradation kinetics and adsorption mass transfer models, this study sheds light on the intricate mechanisms involved, emphasizing the potential of carbon materials as sustainable tools in the ongoing battle for clean and safe groundwater.