SEPARATION AND PURIFICATION TECHNOLOGY
·
2022
·
IF 9.136
Wei Luo,Lin Deng,Jun Hu,Bohui Xu,Chaoqun Tan
Dimetridazole (DMZ) is widely used as a veterinary antibiotic, but it is recalcitrant in the water environment. The residual of DMZ has raised widespread concern because of its harmful effects on human health and environmental safety. This work aimed to investigate the degradation of DMZ and the corresponding formation of halonitromethanes (HNMs) during the ultraviolet (UV)/chlorine process. The UV/chlorine process presented an excellent performance in DMZ degradation. The observed degradation rate constant of DMZ by UV/chlorine was 1.4 × 10 −1 min −1 . The hydroxyl radicals (·OH) and chlorine radicals (·Cl) were the predominant reactive species for DMZ degradation, and corresponding contributions were 79.8% and 13.7%, respectively. With the increase of free chlorine dosage, the degradation efficiency of DMZ firstly increased and then slightly decreased, while the formation of HNMs increased after 40 min UV/chlorine treatment. The higher degradation efficiency of DMZ was observed at acid circumstances, while higher HNMs formation was found at alkaline conditions due to base-catalyzed hydrolysis and less degradation of HNMs. The presences of Cl – , Br – , HCO 3 – and humic acid (HA) inhabited the degradation of DMZ. Furthermore, the possible degradation pathways of DMZ were proposed based on five intermediate products identified by UPLC/MS. Overall, the UV/chlorine was an efficient method for DMZ removal, but the formation of HNMs from DMZ should be evaluated before using UV/chlorine.
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ACS ES&T Water
·
2022
·
IF 0
Yibing Sun,Hongchao Li,Shengli Zhang,Ming Hua,Jieshu Qian,Bingcai Pan
Heterogeneous peroxymonosulfate (PMS)-based advanced oxidation processes (AOPs) are under extensive investigation for their great potential in water remediation. The understanding of the PMS activation mechanism is crucial but still debatable. Here, we describe a thorough investigation of the mechanism involved in PMS activation by using molybdenum disulfide (MoS2) as a catalyst. This MoS2/PMS system exhibited intriguing target-dependent reactivity. Further comprehensive experimental results excluded the major contributions of various possible species, including HO•, SO4•–, O2•–, 1O2, homogeneous Mo(VI), and heterogeneous Mo(VI). We then proposed a surface ≡Mo–OOSO3– complex as the major reactive species, while SO4•– derived from the decomposition of ≡Mo–OOSO3– acted as the secondary reactive species for pollutant removal. This complex could oxidize pollutants through the oxygen-atom-transfer mechanism and perform both nucleophilic and electrophilic attacks. This work provides novel perspectives for the mechanistic understanding of heterogeneous PMS-based AOPs for water remediation.
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Environmental Science-Water Research & Technology
·
2022
·Vol. 8
·期 3
·586-596
·
IF 5.819
Zhiquan Li,Congwei Luo,Fengxun Tan,Daoji Wu,Xuedong Zhai,Shishun Wang,Xiaoxiang Cheng,Fumiao Zhang,Mingli Li,Qiao Ma
As an endocrine disruptor, bisphenol A (BPA) is a severe threat to human health. In this study, nitrate (NO3−) photolysis with a low-pressure UV lamp (LP-UV) was employed to degrade BPA in different aqueous solutions. Results showed that BPA could be decomposed efficiently in the UV/NO3− process. Moreover, the contributions of UV irradiation (4.1%), ˙OH (52.7%), and reactive nitrogen species (43.2%) were obtained. The observed rate constant of BPA degradation (kobs) increased with NO3− concentration since more active species were generated in high NO3− concentration. The BPA degradation rate was significantly accelerated as the pH value rose. This was ascribed to the increase of the molar absorption coefficient and the amount of ionic BPA under alkaline conditions. kobs declining with increasing BPA concentration resulted from the inner filter effect and the competition of more generated intermediate products. The increasing kobs with the addition of HCO3−/CO32− (0–10 mM) was explained as the accumulation of ˙NO2 in the presence of HCO3−/CO32− in UV/NO3− process. The effect of Cl− (0–20 mM) could be ignored in this study, which suggested that reactive chlorine radicals degraded BPA effectively. The kobs reduced acutely when NOM (0–5 mgC L−1) existed in the solution, and this could be ascribed to the dual roles of the NOM inner filter effect and reactive radical scavenging effect. Further, several degradation products were detected, and possible transformation pathways were put forward. Remarkably, the acute toxicity of BPA was slightly enhanced then decayed in the UV/NO3− process.
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Journal of Flow Chemistry
·
2023
·Vol. 13
·期 3
·311-323
·
IF 2.7
Song Jing,Cui Yongjin,Wang Yujun,Wang Kai,Deng Jian,Luo Guangsheng
The nitration of toluene with mixed acid is one of the most representative nitration reactions. Accurate kinetic study is essential for controlling the reaction and designing reactors. Due to the characteristics of fast rate, high exothermicity and heterogeneity in toluene nitration, the effects of mass and heat transfer may result in inaccurate determination of kinetics. In this work, the adiabatic temperature rises of the reaction system were studied to provide precise ranges of experimental conditions for accurately controlling the reaction rate and heat release rate in a liquid–liquid microflow system. The adiabatic temperature rise was successfully controlled to below 0.3 °C. The effects of mass and heat transfer on the reaction rate were completely eliminated, so that the kinetic study was carried out under the control of intrinsic kinetics only. The activation energy for toluene nitration was determined to be 28.00 kJ/mol. The activation energies for the formation of o -nitrotoluene and p -nitrotoluene were obtained for the first time, which were 25.71 and 31.91 kJ/mol, respectively. The obtained kinetic models can predict the reaction performance of toluene nitration very well.
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高影响因子
JOURNAL OF HAZARDOUS MATERIALS
·
2023
·
IF 13.6
Jun Wang,Hao Lv,Xiandong Tong,Wei Ren,Yi Shen,Lun Lu,Yang Zhang
In order to minimize the knowledge gap between single and binary pollutants degradation by persulfate-based advanced oxidation processes (PS-AOPs), iron-loaded N-doped carbon nanotubes (Fe-NCNT) and its acid-washing sample (Fe-NCNT-W) were synthesized as peroxymonosulfate (PMS) activator for simultaneous oxidation of acid orange 7 (AO7) and electron-rich (phenol/ibuprofen) or electron-deficient pollutants (nitrobenzene/benzoic acid). Mechanistic studies revealed that both radical (HO•, SO 4 •− ) and nonradical (electron-transfer, high-valent iron) pathways involved for organic oxidation in Fe-NCNT/PMS system, while electron-transfer pathway (ETP) and high-valent iron-oxo species accounted for pollutant degradation at the surface and inner space of Fe-NCNT-W, respectively. The oxidation performances in single or binary systems were systematically investigated. In comparison to benchmark radical-based (Fe 2+ /PMS), nonradical ETP (NCNT/PMS) and mixed (Fe-NCNT/PMS) systems, Fe-NCNT-W/PMS outperformed superior performance toward oxidation of binary pollutants with little inference from solution pH or background substances, which could also be fabricated into membrane reactor for actual dyeing sewage treatment . Such superiorities should be mainly ascribed to the particular selectivity and intensive treatment of nonradical pathways in Fe-NCNT-W/PMS system with nanoconfinement effect. This work affords novel insights into the treatment of combined pollution via PMS activation by engineered nanomaterials .
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高影响因子
SEPARATION AND PURIFICATION TECHNOLOGY
·
2023
·
IF 8.6
Lunhong Ai,Shiyu Yang,Wei Wei,Yuanyaun Li,Xinyu Zheng,Jing Jiang
Development of a new catalytic system with synergistic multiple active sites to effectively promote the activation of peroxymonosulfate (PMS) is crucial for the control of emerging organic pollutants in water, but it is still challenging. Herein, we explore robust CoP x -implanted porous N-doped carbon frameworks (CoP x @NC) to effectively activate PMS and eliminate tetracycline (TC). The cobalt phosphides in CoP x @NC spontaneously create the distinctive charge imbalance to form asymmetrically charged Co δ+ and P δ− as dual active sites to efficiently enhance catalytic activity, while the positively polarized carbon induced by neighboring electronegative N atoms in CoP x @NC contributes to high catalytic efficiency in parallel. As an advanced catalyst, CoP x @NC displays excellent catalytic performances in PMS activation toward efficient TC degradation with an improved rate constant of 0.137 min −1 and a favorable k-value of 1.43 μmol s −1 g −1 . Mechanistic analysis clearly unveils that the non-radical pathway (singlet oxygen 1 O 2 and direct electron transfer) in CoP x @NC/PMS system dominantly governs the TC degradation along with cooperative radical (SO 4 ·− and ·OH) pathway. This study enriches the charge imbalance strategy for catalyst design and highlights a new catalytic platform to activate PMS for efficient pollutant degradation in water.
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ACS ES&T Engineering
·
2023
·
IF 7.1
Dezhen Kong,Yumeng Zhao,Hongdi Guo,Mei Han,Xinru Fan,Jinkuo Li,Xu He,Jun Ma
The demands for high-efficient and green activation of peracetic acid (PAA) have triggered research in exploring carbon catalysis. Nevertheless, the efforts in designing reaction-oriented and high-performance carbon catalysts are largely impeded by an ambiguous understanding of the fundamental carbon structure–PAA activation performance relationship. Herein, we investigated the quantitative structure–activity relationship (QSAR) of carbon nanotubes (CNTs) for PAA activation and micropollutant (MP) removal, by tuning the physiochemical properties of CNT via thermal annealing. The CNT/PAA system was dominated by the nonradical direct electron transfer (DET) oxidation pathway, showing high MP removal rates under complex water matrices. By conducting QSAR analysis, improved catalytic efficacy of the surface-regulated CNTs was attributed to the reinforced DET via the elevated oxidative potential of the CNT–PAA complex and the enhanced electrical conductivity of CNT. Furthermore, the larger specific surface area and lower oxygen content of CNT gave rise to the elevated oxidative potential of the CNT–PAA complex, while the electrical conductivity of CNT was positively correlated with the graphitization degree of CNT. Overall, this work sheds light on the influence cascade of the physicochemical properties of CNT for MP removal and PAA activation, providing guidelines for the fit-for-purpose design of the DET-mediated carbon catalysts for PAA oxidation.
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JOURNAL OF HAZARDOUS MATERIALS
·
2023
·
IF 13.6
Kaiyuan Luo,Yang Shi,Rongfu Huang,Xipeng Wei,Zelin Wu,Peng Zhou,Heng Zhang,Yin Wang,Zhaokun Xiong,Bo Lai
Periodate (PI) has recently been studied as an excellent oxidant in advanced oxidation processes , and its reported mechanism is mainly the formation of reactive oxygen species (ROS). This work presents an efficient approach using N-doped iron-based porous carbon (Fe@N-C) to activate periodate for the degradation of sulfisoxazole (SIZ). Characterization results indicated the catalyst has high catalytic activity , stable structure, and high electron transfer activity. In terms of degradation mechanism, it is pointed out that the non-radical pathway is the dominant mechanism. In order to prove this mechanism, we have carried out scavenging experiments, electron paramagnetic resonance (EPR) analysis, salt bridge experiments and electrochemical experiments, which demonstrate the occurrence of mediated electron transfer mechanism. Fe@N-C could mediate the electron transfer from organic contaminant molecules to PI, thus improving the efficiency of PI utilization, rather than simply inducing the activation of PI through Fe@N-C. The overall results of this study provided a new understanding into the application of Fe@N-C activated PI in wastewater treatment .
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高影响因子
SEPARATION AND PURIFICATION TECHNOLOGY
·
2023
·
IF 8.6
Xin Liu,Peng Xu,Zhuoyu Yang,Pengfei Zhu,Baolin Hou
Zero-valent copper/air process was studied in degrading contaminants owing to in-site generation of hydrogen peroxide and reactive oxygen species, while its oxidation efficacy was restrained by the dismutation of cuprous ion. In this study, when the dosages of paracetamol, ferric ion, chloride ion and zero-valent copper were respectively 10 μM, 40 μM, 2 mM and 0.2 g/L at pH 3.0, the paracetamol elimination was greatly enhanced and increased from 9.2% to 76.5% within 30 min with adding both ferric ion and chloride ion in the zero-valent copper/air process. Hydroxyl radical and reactive chlorine species were identified as the dominant reactive oxygen species, and the contribution rates of hydroxyl radical and reactive chlorine species to eliminating paracetamol were respectively 68.2% and 28.9%. In the proposed system, zero-valent copper and cuprous ion expedited the ferric/ferrous circulation, conducing to the production of reactive oxygen species. Moreover, chloride ion coupled with cuprous ion producing the cuprous chloride complexes, and chloride ion contributed to the comproportionation between zero-valent copper with cupric ion to form cuprous chloride, receding the dismutation of cuprous ion and contributing to the formation of hydrogen peroxide and reactive oxygen species. When zero-valent copper reused for three times in the proposed system, the degradation of paracetamol reached 62%. After we increased the end pH to > 7.0 and leaching, the total copper of reaction solution was under 0.85 mg/L and the acute toxicity had no insignificant increase for discharge water. The study provided a new idea to enhance zero-valent copper/air system for the purification of pollutants.
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高影响因子
WATER RESEARCH
·
2021
·
IF 11.236
Chenying Zhou,Peng Zhou,Minglu Sun,Yang Liu,Heng Zhang,Zhaokun Xiong,Juan Liang,Xiaoguang Duan,Bo Lai
The sluggish kinetics of Fe(II) recovery strongly impedes the scientific progress of Fenton reaction (Fe(II)/H 2 O 2 ) towards practical application. Here, we propose a novel mechanism that metal-free nitrogen-doped carbon nanotubes (NCNT) can enhance Fenton chemistry with H 2 O 2 as electron donors by elevating the oxidation potential of Fe(III). NCNT remarkably promotes the circulation of Fe(III)/Fe(II) to produce hydroxyl radical ( • OH) with excellent stability for multiple usages (more than 10 cycles) in the NCNT/Fe(III)/H 2 O 2 system. Although carbonyl on NCNT can act as the electron supplier for Fe(III) reduction, the behavior of NCNT is distinct from common reductants such as hydroxylamine and boron. Electrochemical analysis and density functional theory calculation unveil that nitrogen sites of NCNT can weakly bind with Fe(III) to elevate the oxidation potential of Fe(III) (named near-free Fe(III), primarily FeOH 2+ ) at pH ranging from 2.0 to 4.0. Without inputs of external stimulations or electron sacrificers, near-free Fe(III) can promote H 2 O 2 induced reduction of Fe(III) to initiate Fenton chain reactions for long-lasting generation of • OH. To our delight, it is a common property of N-doped carbon materials (e.g., graphene, carbon nanofibers, and acetylene black), our research thus provides a novel, sustainable, and green strategy for promoting Fenton chemistry.
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高影响因子
Journal of Water Process Engineering
·
2021
·
IF 5.485
Wen Huang,Yaxin Tang,Xueping Zhang,Ze Luo,Jianqiang Zhang
The pollution problem of livestock manure generated by the rapid development of farming industry is becoming more and more serious, and its conversion into functional materials through a new way is of great practical significance for its resource utilization. For the first time, nano zero-valent iron (nZVI)/biochar composites (Fe-RMC-850) were prepared by carbonizing Fe 3 O 4 -rabbit dung and used to activate PMS for degradation of sulfamethoxazole (SMX). The results showed that Fe-RMC-850 had high catalytic activity due to its rich pore, high graphitization and defective structure. When the dosage of Fe-RMC-850 and PMS were 0.3 g/L and 0.25 g/L respectively, the degradation rate of SMX could reach 100% within 20 min, and it still showed good catalytic stability after 5 cycles of experiments. The radical quenching, EPR and XPS results showed that radical and nonradical pathways acted synergistically in the degradation of SMX, in which nZVI, Fe 2+ -biochar and pyridinic N were used as the main active sites of the radical pathway. The nonradical pathway was attributed to the generation of C-O and COO by the oxygen-containing functional groups on the biochar surface. Moreover, the inherent P atoms formed P C and CPO 3 /C 2 PO 2 , thereby producing defective structures, while the graphitic carbon layer provided good electron transfer sites. Consequently, this study provides a nZVI-rabbit manure biochar composite PMS catalytic material with high organic pollutant degradation efficiency and offers a new option for the resource utilization of manure sources.
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高影响因子
DALTON TRANSACTIONS
·
2021
·Vol. 50
·期 48
·18061-18068
·
IF 4.39
Jiahui Guo,Xueqing Feng,Songrui Wang,Qikang Wu,Shanshan Lv,Yan Zhou,Han Li,Zheng Chen,Yuzhong Zhang
Novel hexagonal α-cobalt hydroxide nanosheets are synthesized through a 2-methylimidazole-induced hydrolysis strategy with cetyltrimethylammonium bromide (CTAB) as a surfactant. The weak alkaline environment provides favorable conditions for the formation of metastable α-Co(OH)2, while the same raw material will produce β-Co(OH)2 when a strong alkali solution is used. CTAB plays a vital role not only in hexagonal oriented growth, but also in the formation of the hydrotalcite-like structure of α-Co(OH)2 with high crystallinity. The crystallinity of both α- and β-Co(OH)2 is very poor without CTAB as a surfactant. The Co in this Co(OH)2−x layer presents most of the CoII and a small part of the CoIII, and the interlayer nitrate anion balances the positive charge of the host layer. The redox function produced by the CoII and CoIII of α-Co(OH)2 together with the large layer spacing jointly promotes the electron and mass transfer. The use of hydrazine hydrate for transfer hydrogenation involves the transport of protons and electrons produced by decomposition, and the rapid transport is bound to be conducive to the reduction process. Nitro compounds with varieties of functional groups can be smoothly reduced to the corresponding amines with high selectivity, when α-Co(OH)2 was used as a catalyst under mild conditions.
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高影响因子
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