Dissolved copper and iron ions are regarded as friendly and economic catalysts for peroxymonosulfate (PMS) activation, however, neither Cu(II) nor Fe(III) shows efficient catalytic performance because of the slow rates of Cu(II)/Cu(I) and Fe(III)/Fe(II) cycles. Innovatively, we observed a significant enhancement on the degradation of organic contaminants when Cu(II) and Fe(III) were coupled to activate PMS in borate (BA) buffer. The degradation efficiency of Rhodamine B (RhB, 20 mu mol/L) reached up to 96.3% within 10 min, which was higher than the sum of individual Cu(II)- and Fe(III)- activated PMS process. Sulfate radical, hydroxyl radical and high-valent metal ions (i.e., Cu(III) and Fe(IV)) were identified as the working reactive species for RhB removal in Cu(II)/Fe(III)/PMS/BA system, while the last played a predominated role. The presence of BA dramatically facilitated the reduction of Cu(II) to Cu(I) via chelating with Cu(II) followed by Fe(III) reduction by Cu(I), resulting in enhanced PMS activation by Cu(I) and Fe(II) as well as accelerated generation of reactive species. Additionally, the strong buffering capacity of BA to stabilize the solution pH was satisfying for the pollutants degradation since a slightly alkaline environment favored the PMS activation by coupling Cu(II) and Fe(III). In a word, this work provides a brand-new insight into the outstanding PMS activation by homogeneous bimetals and an expanded application of iron-based advanced oxidation processes in alkaline conditions. (c) 2024 The Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences. Published by Elsevier B.V.

To overcome the shortcomings of Fe(Ⅱ)/peroxydisulfate (PDS) system including the limited working pH range and large iron sludge production, a Fe-doped alginate (Fe-Alg) catalyst was prepared and combined with hydroxylamine (HA) to continuously activate PDS for the removal of organic pollutants in neutral condition. Due to the strong reductive capability of HA, it could significantly enhance the catalytic capability of Fe-Alg for PDS. The results of characterization suggested that Fe(Ⅲ)/Fe(Ⅱ) was evenly distributed in Alg through its complexation with carboxyl groups, and the reduction of Fe(Ⅲ) to Fe(Ⅱ) initiated by HA enabled Orange G (OG) to be continuously degraded in the Fe-Alg/HA/PDS system. The results of quenching experiments suggested that SO4∙- and HO• played a dominant role for OG removal in the Fe-Alg/HA/PDS process. The effect of influence factors (e.g. initial pH, HA concentration, Fe-Alg dose and PDS concentration) and water matrix components (i.e. SO42-, NO3-, Cl-, HCO3- and dissolved organic matters (DOM)) on the performance of Fe-Alg/HA/PDS system was systematically investigated. Other refractory organic contaminants, including diclofenac (DCF), sulfamethoxazole (SMX), oxytetracycline (OTC) and bisphenol AF (BPAF) were also efficiently eliminated in Fe-Alg/HA/PDS system, suggesting the feasibility of this system for the treatment of organic pollutants. This work provides a method to optimize Fe(Ⅱ)/PDS system and a novel process applied to degrade refractory pollutants.

Hydrogen-bonded organic frameworks (HOFs) are emerging porous materials that show high structural flexibility, mild synthetic conditions, good solution processability, easy healing and regeneration, and good recyclability. Although these properties give them many potential multifunctional applications, their frameworks are unstable due to the presence of only weak and reversible hydrogen bonds. In this work, the development history and synthesis methods of HOFs are reviewed, and categorize their structural design concepts and strategies to improve their stability. More importantly, due to the significant potential of the latest HOF-related research for addressing energy and environmental issues, this work discusses the latest advances in the methods of energy storage and conversion, energy substance generation and isolation, environmental detection and isolation, degradation and transformation, and biological applications. Furthermore, a discussion of the coupling orientation of HOF in the cross-cutting fields of energy and environment is presented for the first time. Finally, current challenges, opportunities, and strategies for the development of HOFs to advance their energy and environmental applications are discussed.

Although Cu(II)/peroxymonosulfate (PMS) process has been successfully applied to degrade varied organic contaminants in water, the slow transformation of Cu(II) to Cu(I) that works only in alkaline conditions retards the treatment efficiency of this process. In this study, a new finding was observed, that is, oxytetraczdycline (OTC) could effectively enhance the degradation of organic pollutants in Cu(II)/PMS process where it was also removed in acidic conditions. With the addition of OTC in Cu(II)/PMS system, 85.5% of rhodamine B (RhB) was degraded in 90 min at pH 4.0, which was far more than that without OTC (36.1%), and simultaneously 98.1% of OTC was eliminated. The added OTC could form OTC-Cu(II) complexes which might powerfully improve the reduction of Cu(II) to Cu(I), exerting a positive effect on the PMS activation and subsequent degradation of RhB. Electron paramagnetic resonance (EPR) experiments assisted with radical scavenging experiments and Raman spectrum detection results suggested that Cu(III) and hydroxyl radical (HO center dot) were the predominant reactive species for RhB degradation, while OTC removal in this system was mainly ascribed to direct PMS oxidation. The Cu(II)/PMS process also showed a promising success on the synergistic degradation of OTC with the other four refractory organic pollutants, indicating the potential application of PMS oxidation in water treatment.

In recent years, the extensive utilization of ofloxacin (OFX) has led to elevated concentration of OFX compound in the aquatic environment. At the same time, the inherent recalcitrance of OFX has presented a formidable challenge for OFX degradation. In this study, lanthanum cerium perovskite (LaCeO3) was prepared by citric acid sol–gel method to activate bisulfite (BS) for the effective degradation of OFX. The results revealed that the LaCeO3/BS system removed 87.5% of OFX within 180 min with a pseudo-first-order kinetic constant of 3 × 10−3 min−1. Radical quenching experiments and electron paramagnetic resonance (EPR) spectroscopy confirmed that sulfate radicals (SO4•_) and hydroxyl radicals (HO•) were the primary reactive species responsible for OFX removal in LaCeO3/BS system. The reaction mechanism indicated that Ce in LaCeO3/BS system served as the primary active site for BS activation, and a regenerating cycle involving ≡Ce(III)/≡Ce(IV) was present. Additionally, possible intermediate products were identified by a liquid chromatograph-mass spectrometer (LC-MS), revealing potential degradation pathways of OFX. Cycle tests and energy dispersive spectrometer (EDS) data demonstrated the favorable reusability and stability of LaCeO3.

Citric acid (CA) can effectively complex with Fe(III) to improve the solubility of Fe(III) and accelerate the reduction of Fe(III) to Fe(II), while its use in Fe(III)-activated peracetic acid (PAA) system has not been reported so far. Therefore, CA was introduced into Fe(III)/PAA system in this study to degrade oxytetracycline (OTC), and the degradation efficiency and mechanism of OTC in this system were systematically investigated. The results showed that the removal efficiency of OTC in Fe(III)-CA/PAA system at pH 7.0 could reach 81.5% after 20 min, and the degradation of OTC followed pseudo-first-order kinetic. The addition of CA into Fe(III)/PAA system could effectively reduce Fe(III) to Fe(II) driving the cycle of Fe(III)/Fe(II) and accordingly enhance the OTC removal in this system. According to the results of electron paramagnetic resonance (EPR) and scavenging experiments, hydroxyl radical (HO center dot) and organic radicals (CH3C(O)O center dot and CH3C(O)OO center dot) played major roles for the degradation of OTC in Fe(III)-CA/PAA system. Four possible transformation paths of OTC in this system were proposed, including demethylation, hydroxylation, dehydrogenation and dehydration, based on five detected degradation products. This study provides an idea to improve PAA activation by Fe(III) and broadens the practical application of Fe(III) in advanced oxidation processes.

A Cu(II)/heat coactivated peracetic acid (PAA) system for enhancing diclofenac (DCF) degradation was proposed in this work. The superiority of this synergetic activation strategy for PAA, working reactive species, catalytic mechanism and effects of reaction parameters on DCF elimination in this system were simultaneously investigated. Based on our results, the DCF loss rate in Cu(II)-heat/PAA process at pH 8.0 was about 49.3 and 4.2 times of that in Cu(II)/PAA and heat/PAA processes, respectively. Increasing the reaction temperature to 60 оC not only motivated the conversion of Cu(II) to Cu(I) but also facilitated the one-electron transfer between Cu(I) and PAA, boosting the generation of radicals. Organic radicals (mainly CH3C(O)O• and CH3C(O)OO•) were evidenced to be the core oxidizing substances dominating in the destruction of DCF while hydroxyl radical (•OH) made a minor contribution in this system by electron paramagnetic resonance (EPR) method together with scavenging experiments. This study broads the eyes into enhanced PAA activation initiated by homogenous Cu(II), providing a simple but efficient tool to degrade micropollutants.

Since limitedly existing researches suggested Cu(II) had deficiently catalytic ability to PAA, in this work, we tested the oxidation performance of Cu(II)/PAA system on diclofenac (DCF) degradation under neutral conditions. It was found that overwhelming DCF removal could be obtained in Cu(II)/PAA system at pH 7.4 using phosphate buffer solution (PBS) compared to poor loss of DCF without PBS, and the apparent rate constant of DCF removal in PBS/Cu(II)/PAA system was 0.0359 min−1, 6.53 times of that in Cu(II)/PAA system. Organic radicals (i.e., CH3C(O)O• and CH3C(O)OO•) were evidenced as the dominant contributors to DCF destruction in PBS/Cu(II)/PAA system. PBS motivated the reduction of Cu(II) to Cu(I) through chelation effect, and then the activation of PAA by Cu(I) was facilitated. Besides, due to the steric hindrance of Cu(II)-PBS complex (CuHPO4), PAA activation was mediated from non-radical-generating pathway to radical-generating pathway, leading to desirably effective DCF removal by radicals. The transformation of DCF mainly experienced hydroxylation, decarboxylation, formylation and dehydrogenation in PBS/Cu(II)/PAA system. This work proposes the potential of coupling of phosphate and Cu(II) in optimizing PAA activation for organic pollutants elimination.

A novel FeCu anchored coal gangue (FeCu-CG) composite was prepared by a two-step (acidation and subsequent chemical reduction) method and applied in catalytic activation of peracetic acid (PAA) for sulfamethoxazole (SMX) removal in water. The BET, XPS, SEM, EDS, and XRD characterization of FeCu-CG indicated that it had a porous structure with the SBET area of 36.38 m2 g- 1 and nano-FeCu particles were successfully loaded in the CG carrier, which provided electrons and Fe(II) for PAA decomposition through the bimetallic corrosion reaction. The hydroxyl radical (HO center dot) was verified to be largely responsible for SMX elimination in FeCu-CG/PAA system. More than 96.4 % of SMX was removed by FeCu-CG/PAA in 40 min at initial pH ranging from 5.0 to 9.0. Increasing FeCu-CG dosage from 0.1 to 1.0 g L-1 could enhance SMX degradation in FeCu-CG/PAA system, but higher dosage inhibited SMX removal owing to the aggregation of FeCu-CG particles. Coexisting dissolved organic matter (DOM), HCO3- and Cl- suppressed SMX degradation. The degradation pathways of SMX by FeCuCG/PAA were proffered including hydroxylation, amino oxidation, bond cleavage and coupling reaction based on five detected degradation products.

水通道蛋白(AQPs)对水分子具有高选择性和渗透性,是介导水分子转运的膜蛋白.人工水通道一般由各种有机或无机材料(如碳材料、有机化合物以及多肽等)组装而成,旨在模仿天然水通道蛋白的结构和功能.本文介绍了天然、生物启发及合成水通道的种类、结构及其渗透机理,并比较了单分子、超分子及碳纳米材料等人工水通道在近20年间的研究进展.详细地阐述了不同的人工水通道材料特性对结构和功能的影响,并重点剖析了人工水通道的不足以及开发新型人工水通道面临的挑战,最后展望了人工水通道的未来前景.

研究了 Fe2+/过氧乙酸(Fe2+/PAA)高级氧化体系对水中三氯生(TCS)的降解.考察了初始pH、PAA投加量、常见阴阳离子(HCO3-,Cl-,Fe3+,Cu2+)和天然有机物(NOM)对TCS降解的影响,探讨了 TCS在该体系中的降解机理和转化途径.结果表明,TCS在Fe2+/PAA体系中的降解符合准一级反应动力学,其反应速率常数为0.46min-1.在TCS浓度为1 μmol·L-1,初始pH值为3.5、Fe2+投加量为10μmol·L-1、PAA投加量为1 mmol·L-1、反应温度为25℃、反应时间为20 min的条件下,TCS去除率高达95％.水中的NOM通过自由基竞争抑制TCS的降解,而共存阴阳离子的影响较小.HO·氧化是TCS降解的主要途径,但有机自由基对其的氧化作用亦不容忽视.基于TCS降解过程中检出的4种产物,提出了它的转化途径,包含醚键断裂、羟基化和脱氢.

In this work, diclofenac (DCF), a nonsteroidal anti-inflammatory drug, was effectively removed in Cu(Ⅱ)/hydroxylamine (HAm)/peroxydisulfate (PDS) system in neutral condition. It was proved that the introduction of HAm significantly enhanced DCF degradation in Cu(Ⅱ)/PDS system by accelerating Cu(Ι)/Cu(Ⅱ) cycle. According to the results of electron paramagnetic resonance (EPR) and scavenging experiments, the contribution of SO4•- and •OH to DCF degradation in Cu(Ⅱ)/HAm/PDS system was comparable at pH 7. The effects of operational parameters including initial pH, Cu(Ⅱ) dose, HAm concentration, PDS concentration and initial DCF concentration on the removal of DCF were systematically investigated, and the influence of water matrix components (i.e., SO42-, NO3-, Cl-, HCO3- and natural organic matter) on DCF degradation were also studied. Five degradation products were detected using UPLC-Q-TOF-MS, and four degradation pathways were thereby proposed including hydroxylation, dehydrogenation, dehydration and decarboxylation. The mineralization of DCF in Cu(Ⅱ)/HAm/PDS system was limited according to the result of total organic carbon (TOC) test. Various emerging contaminants were also effectively degraded in Cu(Ⅱ)/HAm/PDS system, suggesting the applicability of this system in degradation of other refractory organic contaminants. This study provides a method to enhance the treatment efficiency of Cu(Ⅱ)/PDS system and an effective way to degrade emerging contaminants at mild condition.

Bicarbonate (HCO3-) and humic substances (HS), two common water matrix components, were found to exhibit synergistic effect on diclofenac (DCF) degradation by Cu(Ⅱ)/peracetic acid (PAA) process in this work. The mechanism of their impacts on the performance of Cu(Ⅱ)/PAA system was systematically investigated and the reactive species generated in this system was identified. The results revealed that organic radicals (CH3C(O)OO• and CH3C(O)O•) and Cu(Ⅲ) were both generated in HCO3--Cu(Ⅱ)-fulvic acid (FA)/PAA system, and the presence of FA induced Cu(Ⅲ) to become the dominant reactive species for DCF degradation. In comparison with humic acid (HA), FA showed a stronger enhancement effect on DCF removal in HCO3--Cu(Ⅱ)/PAA system, which might be due to its stronger electron transfer capability. However, DCF degradation in HCO3--Cu(Ⅱ)-HS/PAA system with HA-FA mixture was similar to that with HA alone, because Cu(Ⅱ) was prior to be coordinated with HA in HA-FA mixture. The operating parameters (i.e., HCO3-, Cu(Ⅱ) and PAA concentrations) were optimized for DCF degradation. Finally, the efficient DCF degradation in real waters proved that the presence of HS and HCO3- in real waters also strongly enhanced DCF elimination by Cu(Ⅱ)/PAA process. The findings of this work suggested that HCO3- and HS, which are extensively distributed in aquatic environment, can significantly improve the performance of Cu(Ⅱ)/PAA system and this system may be an efficient technology for the removal of refractory pollutants in real waters.

Diclofenac (DCF), a non-steroidal anti-inflammatory drug, is an emerging and nonbiodegradable contaminant which is detected extensively in aquatic environment. Therefore, low cost and efficient method for DCF degradation has been the aim of many studies. In this study, DCF was efficiently removed by Cu(II)/peracetic acid (PAA) system in the presence of bicarbonate (HCO3-) and carbonate (CO32-). The concentration ratio of HCO3- to CO32- was found to have a significant effect on DCF removal, and the highest removal efficiency of DCF was obtained at [HCO3-](0) : [CO32-](0) = 9:1 due to the formation of CuCO3 and CuCO3(OH)-. According to the results of scavenging experiments and electron paramagnetic resonance (EPR), organic radicals (CH3C(=O)OO center dot and CH3C(=O)O-center dot) were considered to be mainly responsible for DCF degradation in Cu(II)-HCO3-(CO32-)/PAA system. Operational parameters including initial PAA concentration and Cu(II) dosage were optimized for DCF removal, and effect of common water matrix (i.e., natural organic matter, SO42-, NO3- and Cl-) on DCF degradation were systematically investigated. Finally, based on the detected degradation products, five probable degradation pathways of DCF were proposed including hydroxylation, decarboxylation, formylation, dehydrogenation and C-N bond cleavage.

UV/Fe2+/peracetic acid (PAA) as an efficient and novel advanced oxidation system was reported to produce reactive species (i.e., hydroxyl radicals (˙OH) and organic radicals) for triclosan (TCS) degradation.

In this work, the degradation kinetics and mechanism of diclofenac (DCF) using peracetic acid (PAA) activated by zero valent copper (ZVC) were systematically investigated. It was found that PAA could be catalyzed effectively by ZVC to produce HO center dot, CH3COO center dot and CH3COOO center dot, which were responsible for the removal of DCF. Based on the XPS, XRD and FESEM characterization results of ZVC before and after reaction, the corrosion of ZVC was occurred to produce Cu+ under acidic condition, which was the main activator for PAA, H2O2 and O2. The recommended pH for this reaction system was 3.0, and DCF degradation was enhanced gradually with increasing ZVC dose and PAA dose. The existence of Cl-, CO32-, Fe3+, Cu2+ and dissolved organic matter (DOM) promoted DCF degradation in ZVC/PAA system, while SO42- and NO3- had almost no influence on DCF removal. Six intermediates were identified in this system, and the probable degradation mechanism of DCF was thus proposed, including seven transformation pathways, i.e., hydroxylation, amidation, dechlorination-cyclizaiton, dechlorination-hydrogenation, dechlorination-hydroxylation, decarboxylation and formylation. This study provides a new method for PAA activation and DCF removal from the polluted water.

In this study, peracetic acid (PAA) activated by Fe(II) was proposed to remove diclofenac (DCF) in polluted water. It was found that Fe(II)/PAA system could effectively remove DCF at neutral condition, which has a significant advantage over classical Fenton process. According to the result of scavenging experiment, both hydroxyl radical and peroxy radical were considered to be responsible for the degradation of DCF. The influence of several operational parameters including initial pH, Fe(II) dosage, PAA concentration and common water matrix on DCF removal were investigated. 80% DCF was removed at mild condition (pH 6-7) within 60 s, and its removal rate could be enhanced with the increase in Fe(II) dosage and PAA concentration. Presence of HCO3- and natural organic matter (NOM) was proved to have a significantly negative impact on DCF degradation. Four probable degradation pathways of DCF were proposed based on the detected reaction products, including hydroxylation, C-N bond cleavage, decarboxylation and dehydrogenation.

Hydrogen peroxide (H2O2), as a green oxidant, has been widely applied into advanced oxidation processes (AOPs) for the degradation of toxic organic pollutants. The in situ generation of H2O2 can not only improve the storage and transportation safety of H2O2 but also reduce the capital and operation costs. In the present work, a novel system, i.e., multi-walled carbon nanotube‑aluminum (MWCNT-Al) composite was used to in situ generate H2O2 through micro-electrolysis. The MWCNT-Al composite was characterized and optimized. The accumulation concentration of H2O2 reached 947 mg/L at the initial pH of 9.0, the MWCNT-Al composite dosage of 8 g/L and oxygen gas flow rate of 400 mL/min after 60 min. The in situ generation of H2O2 was achieved by MWCNT-Al/O2 system, mainly owing to the direct contact between Al0 and MWCNT in MWCNT-Al composite, which accelerated the transfer of electrons from Al0 to O2, as well as the excellent electrocatalytic activity of MWCNT toward the two-electron reduction of oxygen. When H2O2 in situ generation technology was used in peroxone process (O3/H2O2 process) to degrade glyphosate in aqueous solution, the removal efficiency of TOC and total phosphorus was 68.35% and 73.27%, respectively. Finally, the possible mechanism of in situ generation of H2O2 in MWCNT-Al/O2 system was temporarily proposed.