Environmental Science-Nano
·
2023
·Vol. 10
·期 10
·2744-2753
·
IF 7.3
Jiaxin Lv,Ruixin Chen,Zhen Wu,Yang Bai,Han Song,Chen Tian,Mengye Wang,Zhang Lin
The enrichment of microplastics in polar ice is a typical phenomenon discovered in recent years. Thus, it is worthwhile to explore the degradation behavior of microplastics in frozen environments, which is crucial to evaluate their impact on polar ecosystems. Here, taking polystyrene (PS) as an example, the degradation behaviors of MPs in frozen anoxic Fe(II)-containing solutions were investigated. The results revealed that PS degradation rate in frozen solution was 14.6-fold higher than that in water. Mechanism study showed that freezing-induced aggregation and extrusion of PS enhanced the generation of environmentally persistent free radicals (EPFRs), which in turn contributed to the formation of H2O2. Moreover, freezing-induced enrichment of Fe(II) further interreacted with H2O2 to form Fe(IV) and OH free radicals at a pH of ∼6.5, and thus accelerated the degradation of PS. Such reaction was accompanied by the formation of Fe(III)-containing products, which would further react with aged PS to produce new EPFRs and Fe(II). Such cycles of aged PS/EPFRs and Fe(III)/Fe(II) continued to accelerate the degradation of PS in the frozen solution. This study provides an overlooked pathway for microplastic degradation in frozen Fe(II)-containing solutions, which would be of key importance to understand the degradation behaviors of microplastics in frozen environments.
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SEPARATION AND PURIFICATION TECHNOLOGY
·
2023
·
IF 8.6
Zhipeng Luo,Yao Xu,Diyong Tang,Li Lu,Yuanfang Li,Mengmeng Zhang,Jie Sun
For persulfate-based advanced oxidation process, the non-radical pathway is an important route due to the selective oxidation of pollutants and its strong tolerance to complex water bodies. However, the selective oxidation mechanism of organic pollutants needs further elaboration. Herein, we demonstrate a facile hydrothermal pretreatment and high-temperature carbonization route to synthesize the nitrogen-doped porous biochar (NHBC-1). Owing to the well-developed hierarchical porous structure, the created internal active defects, and tailored nitrogen dopants, the NHBC-1 catalyst exhibited excellent catalytic activity for peroxydisulfate (PDS) activation. The results show that pyridinic N facilitated the adsorption of PDS on NHBC-1 to form the highly active NHBC-PDS* complex. Meanwhile, graphitic N and the defective structures promoted the electron-transfer process, thus allowing the efficient catalytic performance of the NHBC/PDS system for phenol oxidation via an electron-transfer dominated pathway. In addition, the system exhibited versatile applicability for the remediation of various organic pollutants in different actual water matrices with wide pH adaptability and satisfactory mineralization efficiency. More importantly, the selective oxidation mechanism of organic contaminants was revealed. Specifically, only the pollutant with oxidation potential lower than that of the NHBC-PDS* complex (0.91 V) can be effectively eliminated. This study not only provides a facile route for the rational designing of a cost-affordable biochar catalyst for PDS activation, but also offers valuable insights into the understanding of selective oxidation of organic contaminants via an electron-transfer dominated pathway.
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ENVIRONMENTAL RESEARCH
·
2023
·
IF 8.3
Fengguo Tian,Jianzhi Qiao,Wentian Zheng,Yang Lei,Shengtao Jiang,Yanbiao Liu
Phosphorus scarcity and the deleterious ecological impact of the release of organophosphorus pesticides have emerged as critical global issues. Previous research has shown the ability of electrochemistry to induce the precipitation of calcium phosphate from phosphorus-laden wastewater to recover the phosphorus. The current study presents a flow-through electrochemical system consisting of a column-shaped electrochemical reactor, a tubular stainless-steel (SS) cathode, and a titanium suboxides (TiSO) anode. This system simultaneously oxidizes tetrakis (hydroxymethyl) phosphonium sulfate (THPS) and recycles phosphates. The influence of current density, flow rate, and initial calcium ions concentration were examined under continuous flow operation. To enhance the electrochemical reactor's performance, we elevated the current density from 5 to 30 mA cm −2 , which caused the phosphorus recovery efficiency to increase from 37% to 72% within 120 min, accompanied by an enhancement of the THPS mineralization efficiency from 57% to 90%. These improvements were likely due to the higher yield of reactive species chloride species (Cl • ) formed at the TiSO anode and the higher local pH at the cathode. By investigating the formation of Cl • at the TiSO anode, we found that THPS mineralization exceeded 75% in the presence of NaCl at a current density of 20 mA cm −2 . The demonstrated performance of the flow-through electrochemical system should enable the utilization of anodic oxidation-cathodic precipitation for the recovery of phosphorus from organophosphorus-contaminated wastewater.
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CHEMICAL ENGINEERING JOURNAL
·
2023
·
IF 15.1
Xinwei Zhu,Jimin Shen,Jing Kang,Pengwei Yan,Lei Yuan,Yizhen Cheng,Binyuan Wang,Shengxin Zhao,Zhonglin Chen
Developing highly efficient and anti-interference catalysts was still a challenge for the practical application of heterogeneous catalytic ozonation (HCO) in water decontamination. Herein, a magnetic Fe 3 C decorated biochar (Fe 3 C/BC) was prepared for HCO to achieve efficient degradation of 2,4-dichlorophenoxyacetic acid (2,4-D). The Fe 3 C/BC catalytic ozonation system promoted the degradation ratio of 2,4-D from 58.7% (ozonation alone) to 90.0% within 10 mins when the ozone dosage was 1.0 mg/L. And the observed degradation rate constant ( k obs ) of 2,4-D under catalytic ozonation system was 2.58 times that of ozonation alone. Fe 3 C/BC exhibited negligible adsorption on 2,4-D but with a significant enrichment to ozone, which realized the cooperating process of “adsorption-catalysis” at the solid–liquid interface, thus avoiding the ineffective decomposition of ozone. The dissociative adsorption of ozone molecules on the surface Fe 3 C generated surface atomic oxygen species (O* and O 2 *), which mediated the in-situ formation of hydroxyl radicals (·OH). ATR-FTIR, in-situ Raman, isotope tracing tests, and theoretical calculations were used to disclose the interface reaction processes and reveal the ·OH formation mechanism. Free radical reactions at the interface efficiently avoid the interference of coexisting ions dissolved in water. The presence of 3 mM (183 mg/L) bicarbonate had essentially little effect on the degradation of 2,4-D. The consecutive use of Fe 3 C/BC did not influence its catalytic performance and stable structure. This study provided new insight into the ·OH-dominated interfacial reaction in the HCO process.
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MICROCHIMICA ACTA
·
2023
·Vol. 191
·期 1
·1-11
·
IF 5.7
Guo Zhanghong,Zhou Lin,Chen Xuan,Song Qijun
Carbon-coated copper nanocrystals (CuNCs) with peroxidase-like activity were hydrothermally prepared by using copper acetate, citric acid (CA) and histidine (His) as the precursors. Various shaped CuNCs, including urchin-like, slab-like and spherical appearance were facilely prepared by addition of different amount of NaNO 2 in the precursor solutions. When 3,3′,5,5′-tetramethylbenzidine (TMB) was used as the substrate, the CuNCs with urchin-like appearance have greatest peroxidase-like activity and their Michaelis–Menten constant ( K m ) and the maximum rate constant (ν max ) are respectively 8.8 and 1.2 times higher than that obtained from horseradish peroxidase (HRP). The production of reactive oxygen species (ROS) was confirmed by radical quenching and electron spin resonance (ESR) tests. Subsequent studies have found that the CuNCs catalyzed color reaction of TMB can be selectively quenched by the environmental pollutant 2,4-dinitrophenylhydrazine (2,4-DNPH). Thus a new colorimetric method for the determination of 2,4-DNPH with a linear range of 0.60–20 µM was developed and a limit of detection (LOD) as low as 0.166 µM was achieved. The results obtained not only reveal the tunability of the peroxidase-like activity of Cu-based nanomaterials, but also provide a new method for the sensitive determination of environmental contaminate. Graphical abstract
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CHEMICAL ENGINEERING JOURNAL
·
2023
·
IF 15.1
Jinxiang Zuo,Donglei Fu,Pengwei Yan,Shuyu Wang,Yabin Li,Linlu Shen,Yizhen Cheng,Jimin Shen,Jing Kang,Zhonglin Chen
In this study, Al-doped NiFe 2 O 4 (NiAl x Fe 2-x O 4 ) was synthesized by the isomorphic substitution strategy, which was further employed for peroxymonosulfate (PMS) activation to remove 2,4-dichlorophenoxyacetic acid (2,4-D) in water. Doping of Al could construct oxygen vacancies (OVs) in the structure of NiAl x Fe 2-x O 4 , which further facilitates the exposure of metal sites for PMS activation. The removal rate of 2,4-D increased greatly compared to the NiFe 2 O 4 -activated process. By the density functional theory (DFT) process, it was verified that Al was more likely to replace Fe rather than Ni. OVs sites have the lowest adsorption energy of H 2 O ( E ads = -0.95 eV), and easily formed surface hydroxyl groups (–OH), which were further replaced by PMS (HSO 5 - ). The formed surface complex Me-O-O-SO 3 - was readily activated via electron transfer between O-O bond, thus promoting the cleavage of it and inducing SO 4 · - generation. This process induced the high performance of the NiAl x Fe 2-x O 4 /PMS system for effective 2,4-D degradation. Furthermore, the purified water showed relatively low toxicity. The present study proposed new insights into the interface mechanism of PMS triggering.
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SEPARATION AND PURIFICATION TECHNOLOGY
·
2023
·
IF 8.6
Wenyuan Lu,Lanyue Qi,Dachang Dong,Xianbao Shen,Lijie Xu,Ying Zhang,Xiang Mei,Weichuan Qiao,Xuewen Guo,Yuwei Pan
In this study, g-C 3 N 4 catalysts were prepared from six different precursors including urea, melamine and its hydrochloride, dicyandiamide, thiourea, trithiocyanuric acid to compare their photocatalytic performance and the activation of three commonly seen peroxides, i.e., H 2 O 2 , peroxymonosulfate (PMS), and peroxydisulfate (PDS) under visible light irradiation. The structural and photoelectric properties were analyzed systematically. Results showed that the g-C 3 N 4 synthesized from trithiocyanuric acid (TCA-CN) showed the largest SSA (56.59 m 2 /g), the narrowest band gap (2.621 eV), and lowest carriers’ recombination rate, which correspondingly exhibited the best photocatalytic performance for the degradation of bisphenol A (BPA). Moreover, the g-C 3 N 4 synthesized by urea (U-CN) demonstrating the strongest photoelectron density, widest band gap (2.790 eV) and the most positive VB potential showed the highest activating efficiencies of all three oxidants. In general, persulfates were more competent to enhance the degradation of BPA than H 2 O 2 , and PMS showed the highest activity. The dominant reactive oxidation species (ROS) depended more on the type of peroxides than on the catalyst precursors. The effective activation of PDS by U-CN was primarily resulting from the photoelectrons to produce extra •OH to enhance compounds degradation, and high yield of 1 O 2 could be achieved by PMS activation through h + oxidation, leading to the most significant enhancement of BPA removal. The N–C 3 and NH x of U-CN were likely the sites for PMS activation. Moreover, the U-CN/LED/PMS process showed the strong adaptability to the complex water environment. This work may provide new insights into selecting highly efficient g-C 3 N 4 -based advanced oxidation processes for water remediation.
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SEPARATION AND PURIFICATION TECHNOLOGY
·
2023
·
IF 8.6
Niannian Tang,Chengbo Qian,Chengwen Zhang,Yuyuan Yao
Developing uniformly dispersed iron-based catalysts with high metal loading for selective removal of the phenolic compounds was a fundamental challenge in environmental catalysis. An isolation anchoring strategy was devised to prepare the uniformly dispersed nitrogen-doped porous carbon encapsulating iron catalyst (β-Fe@NC) with the Fe loading up to 16.33 wt%, which was attributed to a dual protective effect including anchoring effect of the 8-hydroxyquinoline (8-HQ) and isolation effect of the β-cyclodextrin (β-CD), effectively anchoring the iron and inhibiting the agglomeration of the iron nanoparticles (NPs) during high temperature pyrolysis. As a demonstration, β-Fe@NC achieved almost 100% 4-CP removal in 25 min and performed an excellent k obs (0.325 min −1 ). Moreover, β-Fe@NC showed highly selective removal performance for phenolic compounds based on the hydrophobic interaction between catalysts and contaminants. The quenching experiments and EPR detection demonstrated that the main reactive oxygen species (ROSs) was singlet oxygen ( 1 O 2 ). Notably, the β-Fe@NC/PMS system exhibited an extremely low activation energy (11.54 KJ/mol) and was even competent for pollutant removal at 0 °C. This work provides a valuable insight for the design of uniformly dispersed iron-based catalysts and the activation of PMS to selectively remove phenolic compounds.
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ChemElectroChem
·
2023
·Vol. 10
·期 18
·e202300255
·
IF 4
Jia Shen,Yating Zhu,Fengmei Zhou,Luyu Wang,Manli Guo,Yujuan Cao
Graphical Phosphorus-doped porous carbon coated graphite felt (P-GF) : It exhibited excellent hydrophilicity and infiltrating property, and it enhanced electrochemical reduction of O 2 and could significantly enhance the yield of H 2 O 2 . About 98.5 % of methylparaben could be degraded within 180 min, and four parabens could be simultaneously removed. The P-GF exhibited outstanding reusability. Pharmaceuticals and personal care products (PPCPs) are currently drawing significant attention due to their environmental impact. Electro-Fenton, one of the advanced oxidation processes (AOPs), is an efficient and comprehensive technology to degrade all kinds of organic pollutants, but the degradation efficiency relies on cathode material. In this work, phosphorus-doped porous carbon material coated graphite felt (P-GF) was prepared by adopting phytic acid as a phosphorus source through high temperature solid-state method. The microstructure and the elements composition of this fabricated material were investigated by SEM, BET and XPS. With phosphorus doping and plenty of carbon porous structures, the hydrophilicity and infiltrating property of the P-GF had been greatly improved. The prepared P-GF material enhanced the electrochemical reduction of O 2 and could significantly enhance the yield of H 2 O 2 . It was used as a cathode to degrade pollutants under a constant potential, and methylparaben (MePa) was chosen as a research model for optimizing the experimental conditions and analyzing the possible degradation pathway. The P-GF cathode achieved an excellent ability of degrading nearly 100 % of methylparaben within 3 h. The simultaneous removal ability of the P-GF to four parabens was impressed. Additionally, the P-GF material exhibited outstanding reusability.
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ENVIRONMENTAL SCIENCE & TECHNOLOGY
·
2023
·
IF 11.4
Shuang Meng,Minglu Sun,Peng Zhang,Chenying Zhou,Chuanshu He,Heng Zhang,Yang Liu,Zhaokun Xiong,Peng Zhou,Bo Lai
The continuous electron supply for oxidant decomposition-induced reactive oxygen species (ROS) generation is the main contributor for the long-standing micropollutant oxidation in the iron-based advanced oxidation processes (AOPs). Herein, as a new class of co-catalysts, metal borides with dual active sites and preeminent conductive performance can effectively overcome the inherent drawback of Fenton-like reactions by steadily donating electrons to inactive Fe(III). Among the metal borides, tungsten boride (WB) exhibits a significant co-catalytic performance run ahead of common heterogeneous co-catalysts and exceptionally high stability. Based on qualitative and semi-quantitative tests, the hydroxyl radical, sulfate radical, and iron(IV)-oxo complex are all produced in the WB/Fe(III)/PDS system and Fe(IV)-induced methyl phenyl sulfoxide decomposition is up to 72%. Moreover, the production efficiency of ROS and relative proportions of radical and nonradical pathways change with various experimental conditions (dosages of PDS, WB, and solution pH) and water matrices. The rate-determining step of Fe(II) regeneration is greatly accelerated resulting from the synergetic effect between exposed metallic reactive sites and nonmetallic boron with reductive properties of WB. In addition, the self-dissolution of surface tungsten oxide and boron oxide leads to a renovated surface for sustainable Fe(III) reduction in long-term operations. Our discovery provides an efficient and sustainable strategy in the field of enhanced AOPs for water remediation.
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SEPARATION AND PURIFICATION TECHNOLOGY
·
2023
·
IF 8.6
Ruijie Xie,Ziyi Suo,Kaiheng Guo,Fada Feng,Bang Lan,Tao Zhang,Guangqin Li,Haibao Huang
Advanced oxidation processes (AOPs) could effectively remove volatile organic compounds (VOCs) when coupled with wet scrubbing process. However, it still faces challenges in achieving deep oxidation of VOCs due to the limited production of reactive oxygen species (ROS). Herein, we present the utilization of permanganate (KMnO 4 ) as a co-oxidant to enhance VOCs oxidation in UV/persulfate (PDS)/KMnO 4 system. The removal efficiency of a targeted VOC, toluene, kept high at above 90% throughout the entire long-term reaction of 4 h, which was much higher than that of UV/PDS and UV/KMnO 4 . Notably, the in-situ formed manganese oxide (MnO x ) acts as a catalyst in UV/MnO x and UV/MnO x /PDS, facilitating the generation of various ROS and thereby enhancing VOCs degradation. Electron paramagnetic resonance (EPR) and quenching experiments indicated that sulfate radical (SO 4 − ), hydroxyl radical (HO ), superoxide radical ( O 2 − ) and singlet oxygen ( 1 O 2 ) were the main ROS generated in the UV/PDS/KMnO 4 system. The overall oxidation process can be divided into three stages: the UV/KMnO 4 -dominated stage, the UV/MnO x /PDS-dominated stage, and the UV/MnO x -dominated stage. Correspondingly, HO played a major role in toluene oxidation in the UV/KMnO 4 -dominated and UV/MnO x -dominated stages, with the contributions of 48% and 52%, respectively. Meanwhile, SO 4 − played a more significant role in the UV/MnO x /PDS-dominated stage, with a contribution of 59%. Three main reaction pathways involving electron abstraction, HO addition and benzene ring opening were proposed based on the intermediates identified by proton-transfer-reaction mass spectrometry (PTR-MS). This study provided a deep understanding of KMnO 4 in improving the oxidation capacity of UV-based AOPs for VOCs degradation, emphasizing the importance of in-situ formed MnO x for promoting multiple ROS generation.
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Journal of Environmental Chemical Engineering
·
2023
·
IF 7.7
Yiqing Liu,Lin Tian,Zhenran Wang,Yongsheng Fu,Dandan Zhao
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 • ) and organic radicals (CH 3 C(O)O • and CH 3 C(O)OO • ) 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 .
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