2022
Juve J-MA, Li F, Zhu Y, Liu W, Ottosen LDM, Zhao D, Wei Z.
Concentrate and degrade PFOA with a photo-regenerable composite of In-doped TNTs@AC. Chemosphere [Internet]. 2022;300:134495.
访问链接Abstract“Concentrate-and-degrade” is an effective strategy to promote mass transfer and degradation of pollutants in photocatalytic systems, yet suitable and cost-effective photocatalysts are required to practice the new concept. In this study, we doped a post-transition metal of Indium (In) on a novel composite adsorptive photocatalyst, activated carbon-supported titanate nanotubes (TNTs@AC), to effectively degrade perfluorooctanoic acid (PFOA). In/TNTs@AC exhibited both excellent PFOA adsorption (>99% in 30 min) and photodegradation (>99% in 4 h) under optimal conditions (25 °C, pH 7, 1 atm, 1 g/L catalyst, 0.1 mg/L PFOA, 254 nm). The heterojunction structure of the composite facilitated a cooperative adsorption mode of PFOA, i.e., binding of the carboxylic head group of PFOA to the metal oxide and attachment of the hydrophobic tail to AC. The resulting side-on adsorption mode facilitates the electron (e‒) transfer from the carboxylic head to the photogenerated hole (h+), which was the major oxidant verified by scavenger tests. Furthermore, the presence of In enables direct electron transfer and facilitates the subsequent stepwise defluorination. Finally, In/TNTs@AC was amenable to repeated uses in four consecutive adsorption-photodegradation runs. The findings showed that adsorptive photocatalysts can be prepared by hybridization of carbon and photoactive semiconductors and the enabled “concentrate-and-degrade” strategy is promising for the removal and degradation of trace levels of PFOA from polluted waters.
Fan J, Sun X, Liu Y, Zhao D, Hao X, Liu W, Cai Z.
New insight into environmental photochemistry of PAHs induced by dissolved organic matters: A model of naphthalene in seawater. Process Safety and Environmental Protection [Internet]. 2022;161:325-333.
访问链接AbstractThe photochemical behavior of a model PAH, naphthalene, was investigated under simulated sunlight irradiation with different dissolved organic matter (DOM) in seawater. The results revealed that naphthalene was prone to direct photolysis (Φd = 1.34 × 10-3) and could be degraded by 3DOM*/1O2-induced reactions with fulvic acid (FA) and humic acid (HA) at low concentrations. However, the DOM at a high level dramatically decreased the kobs due to the higher light attenuation and radical competition effect. The presence of FA resulted in lower 3DOM*/1O2 generation and quantum yield compared with HA, but it achieved higher degradation kinetics due to the higher reactivity between 3FA* and naphthalene and their lower binding effect. The naphthalene degradation in natural water with different depths and DOM were modeled based on the experimental results, which revealed the important role of indirect photolysis initiated by inorganic constituents. Moreover, several degradation intermediates were identified by GC-MS and three possible pathways were proposed. The Quantitative Structure Activity Relationships (QSAR) evaluation revealed that some intermediates are more toxic than original naphthalene. This study offers further insights into the photochemical behavior of PAHs, which will facilitate our understanding of the persistence and ecological risks of organic contaminants in natural waters.
Liu X, Li F, Liu Y, Li P, Chen L, Li B, Qian T, Liu W.
Degradation of diclofenac in a photosensitization-like photocatalysis process using palladium quantum dots deposited graphite carbon nitride under solar light. Journal of Environmental Chemical Engineering [Internet]. 2022;10:107545.
访问链接AbstractThe widely spilled diclofenac (DCF) in water has attracted broad attention because of its potential environmental risk. In this work, palladium quantum dots (PQDs) deposited g-C3N4 photocatalysts (PCNs) were fabricated through a two-step process, i.e., initial thermal polymerization followed by an in-situ reduction for PQDs deposition. In addition, the synthesized g-C3N4 (43.09 m2/g) composing of ultrathin sheets had 4 times larger specific surface area than bulk g-C3N4 (8.73 m2/g), thus offered abundant sites for reaction. The optimized material (PCN2) with 1 wt% PQDs loading content achieved the highest cost-efficiency for DCF degradation, and exhibited a kinetic rate constant (k1) of 0.072 min−1, which was 8 times higher than bulk g-C3N4. The mechanisms on enhanced photocatalytic activity of PCN are interpreted as: (1) decoration of PQDs can alter the optical band structure of g-C3N4, leading to a narrowed bandgap; (2) PQDs can act as electron transfer mediator to retard the recombination of photogenerated charge carriers; and (3) a photosensitization-like electron transfer pathway occurs from highest occupied molecular orbital (HOMO) of DCF to conduction band (CB) of g-C3N4 by means of PQDs. Radical quenching experiments and electron spin resonance (ESR) analysis indicated •O2- was the primary radical for DCF degradation. Density functional theory (DFT) calculation combined intermediates identification further revealed that the Cl11 and N12 atoms with high Fukui index (f 0) were more venerable to attack. PCN2 also remained good stability after five continuous cycles for DCF degradation, showing the great potential for practical application in water treatment area.
Wang J-F, Liu Y, Shao P, Zhu Z-Y, Ji H-D, Du Z-X, Wang C-C, Liu W, Gao L-J.
Efficient ofloxacin degradation via photo-Fenton process over eco-friendly MIL-88A(Fe): Performance, degradation pathways, intermediate library establishment and toxicity evaluation. Environmental Research [Internet]. 2022;210:112937.
访问链接AbstractThe high-throughput production of the eco-friendly MIL-88A(Fe) was achieved under mild reaction conditions with normal pressure and temperature. The as-prepared MIL-88A(Fe) exhibited efficient photo-Fenton catalytic ofloxacin (OFL) degradation upon visible light irradiation with good stability and reusability. The OFL (20.0 mg/L) was completely degraded within 50 min under visible light with the aid of MIL-88A(Fe) (0.25 g/L) and H2O2 (1.0 mL/L) in aqueous solution (pH = 7.0). The hydroxyl radicals (·OH) are the main active species during the photo-Fenton oxidation process. Meanwhile, the degradation intermediates and the corresponding degradation pathways were identified and proposed with the aid of both ultra-high performance liquid chromatography tandem quadrupole time-of-flight mass spectrometry (UHPLC-Q-TOF-MS) and density functional theory (DFT) calculations. Finally, the degradation product library was firstly established to identify intermediate transformation products (TPs) with their variation of concentration, and their corresponding toxicologic activities were assessed via Toxtree and T.E.S.T software as well. Finally, the MIL-88A is efficient and stable with four cycles’ catalysis operations, demonstrating good potential for water treatment.
Liu Z, Liu Y, Sun X, Ji H, Liu W, Cai Z.
Construction of Z-scheme Ag/AgVO3/carbon-rich g-C3N4 heterojunction for enhanced photocatalytic degradation of sulfamethiadiazole: DFT calculation and mechanism study. Chemical Engineering Journal [Internet]. 2022;433:133604.
访问链接AbstractA novel Z-scheme Ag/AgVO3/carbon-rich g-C3N4 heterojunction with excellent solar-light-driven photocatalytic activity was constructed via a facile hydrothermal-calcining method. The Ag/AgVO3/carbon-rich g-C3N4 composites displayed superior performance for the photocatalytic degradation of sulfamethiadiazole (SFZ) under solar irradiation. The optimal composite with a 10 wt% Ag/AgVO3 content showed the highest photocatalytic activity, its degradation rate constant (k) for SFZ degradation was ∼13 and 30 times than that of carbon-rich g-C3N4 (CCN) and Ag/AgVO3, respectively. Furthermore, •O2– was identified as the most crucial reactive species in the Z-scheme photocatalysis system. The greatly improved photocatalytic activities are derived from the built-in electric field (BIEF) of CCN and efficient Z-scheme charge transfer with Ag nanoparticles as charge transmission-bridge. The possible photocatalytic degradation mechanism and pathway over Ag/AgVO3/carbon-rich g-C3N4 were proposed based on LC-MS analysis and density functional theory (DFT) calculation, and the toxicity of intermediates was evaluated by Quantitative structure–activity relationship (QSAR) based prediction. In summary, this work provides new insight into constructing highly efficient Z-scheme photocatalyst, which is promising for implementation in surface water remediation.
Du P, Liu W, Rao Z, Wang J.
Accelerated Oxidation of Organic Micropollutants during Peracetic Acid Treatment in the Presence of Bromide Ions. ACS ES&T Water [Internet]. 2022;2:320-328.
访问链接AbstractPeracetic acid (PAA), an alternative disinfectant of chlorine, has drawn increasing attention in the application of wastewater treatment. However, little is known about the influence of water matrices on PAA-induced organic micropollutant (OMP) degradation. Here, we found that the coexisting bromide ions (Br–) in water can trigger the oxidation of OMP during PAA treatment but probably result in higher ecotoxicity. Br– can efficiently decompose PAA with a species-specific rate constant (kPAAH/Br–) of 0.198 ± 0.003 M–1·s–1. The thus generated HOBr led to a significant abatement (31.8–81.3%) of OMPs (17α-ethinylestradiol, sulfamethoxazole, naproxen, and phenol) after a 1 h reaction at pH 7.1. The coexisting H2O2 component in the PAA solution can competitively consume HOBr and inhibit OMP transformation. The OMP degradation in the PAA/Br– process was highly pH-dependent and preferred acidic conditions. Furthermore, a comprehensive model was established to simulate the reaction kinetics of the OMP degradation by the PAA/Br– process with good accuracy. High-performance/electrospray ionization-triple quadrupole mass spectrometry results indicated the generation of various brominated products, with higher model-predicted toxicity than their parent compounds. This work significantly advances the understanding of the role of Br– in OMP oxidation by PAA and alerts the possible environmental health risks.
Pan F, Ye Y, Wang Q, Fu J, Xia D, Liu W.
Effect and Mechanism of Titanium Nanomaterials on Microbial Community Structure and Function in Sequencing Batch Reactor. ACS ES&T Water [Internet]. 2022;2:395-404.
访问链接Abstract{ A series doses (0–1.0 g/L) of titanium dioxide (TiO2) and titanate nanotubes (TNTs) were added into the sequencing batch reactor (SBR) to investigate the biological effect of titanium nanomaterials. TNTs and TiO2 showed a moderate suppressing effect on SBR performance, while TiO2 seemed to be more toxic. Further, 0.04 g/L TiO2 resulted in significant inhibition on the removal of methylene blue (p < 0.05
Luo M, Zhang H, Zhou P, Xiong Z, Huang B, Peng J, Liu R, Liu W, Lai B.
Efficient activation of ferrate(VI) by colloid manganese dioxide: Comprehensive elucidation of the surface-promoted mechanism. Water Research [Internet]. 2022;215:118243.
访问链接AbstractCurrent research focuses on introducing additional energy or reducing agents to directly accelerate the formation of Fe(IV) and Fe(V) from ferrate (Fe(VI)), thereby ameliorating the oxidation activity of Fe(VI). Interestingly, this study discovers that colloid manganese dioxide (cMnO2) can remarkably promote Fe(VI) to remove various contaminants via a novel surface-promoted pathway. Many lines of evidence suggest that high-valent Fe species are the primary active oxidants in the cMnO2−Fe(VI) system, however, the underlying activation mechanism for the direct reduction of Fe(VI) by cMnO2 to generate Fe(IV)/Fe(V) is eliminated. Further analysis found that Fe(VI) can combine with the vacancies in cMnO2 to form precursor complex (cMnO2−Fe(VI)*), which possesses a higher oxidation potential than Fe(VI). This makes cMnO2−Fe(VI)* is more vigorous to oxidize pollutants with electron-rich moieties through the electron transfer step than alone Fe(VI), resulting in producing Fe(V) and Fe(IV). The products of Fe(VI) decay (i.e., Fe(II), Fe(III), and H2O2) are revealed to play vital roles in further boosting the formation of Fe(IV) and Fe(V). Most importantly, the catalytic stability of cMnO2 in complicated waters is superior to popular reductants, suggesting its outstanding application potential. Taken together, this work provides a full-scale insight into the surface-promoted mechanism in Fe(VI) oxidation process, thus providing an efficient and green strategy for Fe(VI) activation.
Du P, Wang J, Sun G, Chen L, Liu W.
Hydrogen atom abstraction mechanism for organic compound oxidation by acetylperoxyl radical in Co(II)/peracetic acid activation system. Water Research [Internet]. 2022;212:118113.
访问链接AbstractPeracetic acid (PAA) has been widely used as an alternative disinfectant in wastewater treatment, and PAA-based advanced oxidation processes (AOPs) have drawn increasing attention recently. Among the generated reactive species after PAA activation, acetylperoxyl radical (CH3CO3•) plays an important role in organic compounds degradation. However, little is known about the reaction mechanism on CH3CO3• attack due to the challenging of experimental analysis. In this study, a homogeneous PAA activation system was built up using Co(II) as an activator at neutral pH to generate CH3CO3• for phenol degradation. More importantly, reaction mechanism on CH3CO3•-driven oxidation of phenol is elucidated at the molecular level. CH3CO3• with lower electrophilicity index but much larger Waals molecular volume holds different phenol oxidation route compared with the conventional •OH. Direct evidences on CH3CO3• formation and attack mechanism are provided through integrated experimental and theoretical results, indicating that hydrogen atom abstraction (HAA) is the most favorable route in the initial step of CH3CO3•-driven phenol oxidation. HAA reaction step is found to produce phenoxy radicals with a low energy barrier of 4.78 kcal mol−1 and free energy change of -12.21 kcal mol−1. The generated phenoxy radicals will undergo further dimerization to form 4-phenoxyphenol and corresponding hydroxylated products, or react with CH3CO3• to generate catechol and hydroquinone. These results significantly promote the understanding of CH3CO3•-driven organic pollutant degradation and are useful for further development of PAA-based AOPs in environmental applications.
Ding P, Ji H, Li P, Liu Q, Wu Y, Guo M, Zhou Z, Gao S, Xu W, Liu W, et al. Visible-light degradation of antibiotics catalyzed by titania/zirconia/graphitic carbon nitride ternary nanocomposites: a combined experimental and theoretical study. Applied Catalysis B: Environmental [Internet]. 2022;300:120633.
访问链接AbstractDevelopment of low-cost, high-performance photocatalysts for the effective degradation of antibiotics in wastewater is critical for environmental remediation. In this work, titanium dioxide/zirconium dioxide/graphitic carbon nitride (TiO2/ZrO2/g-C3N4) ternary composites are fabricated via a facile hydrothermal procedure, and photocatalytically active towards the degradation of berberine hydrochloride under visible light illumination. The performance is found to increase with the Ti:Zr atomic ratio in the nanocomposites, and obviously enhanced in comparison to that of the binary TiO2/g-C3N4 counterpart, due to the formation of type I/II heterojunctions that help separate the photogenerated electron-hole pairs and produce superoxide and hydroxy radicals. The mechanistic pathways are unraveled by a deliberate integration of liquid chromatography-mass spectrometry measurements with theoretical calculations of the condensed Fukui index. Furthermore, the ecotoxicity of the reaction intermediates is examined by utilizing the Toxicity Estimation Software Tool (TEST) and quantitative structure activity relationship calculations (QSAR).
Wu Y, Ji H, Liu Q, Sun Z, Li P, Ding P, Guo M, Yi X, Xu W, Wang C-C, et al. Visible light photocatalytic degradation of sulfanilamide enhanced by Mo doping of BiOBr nanoflowers. Journal of Hazardous Materials [Internet]. 2022;424:127563.
访问链接AbstractDesign of high-efficiency visible light photocatalysts is critical in the degradation of antibiotic pollutants in water, a key step towards environmental remediation. In the present study, Mo-doped BiOBr nanocomposites are prepared hydrothermally at different feed ratios, and display remarkable visible light photocatalytic activity towards the degradation of sulfanilamide, a common antibacterial drug. Among the series, the sample with 2% Mo dopants exhibits the best photocatalytic activity, with a performance 2.3 times better that of undoped BiOBr. This is attributed to Mo doping that narrows the band gap of BiOBr and enhances absorption in the visible region. Additional contributions arise from the unique materials morphology, where the highly exposed (102) crystal planes enrich the photocatalytic active sites, and facilitate the adsorption of sulfanilamide molecules and their eventual attack by free radicals. The reaction mechanism and pathways are then unraveled based on theoretical calculations of the Fukui index and liquid chromatography/mass spectrometry measurements of the reaction intermediates and products. Results from this study indicate that deliberate structural engineering based on heteroatom doping and morphological control may serve as an effective strategy in the design of highly active photocatalysts towards antibiotic degradation.
Dang C, Jiang H, Zheng M, Li Z, Liu W, Fu J.
Chapter 17 The Different Toxicity and Mechanism of Titanium Dioxide (TiO2) and Titanate Nanotubes (TNTs) on Escherichia coli. In: Emerging Nanotechnologies for Water Treatment. The Royal Society of Chemistry; 2022. pp. 507-522.
访问链接AbstractAs typical titanium nanomaterials, TiO2 and titanate nanotubes (TNTs) are extensively used. Although the toxicity of nano-TiO2 under solar light has been investigated, it is not enough to evaluate its environmental toxicity because the dark environment is also important in the natural environment. In addition, little is known about the environmental toxicity and mechanism of the emerging TNTs. In this study, we investigated the toxicity of nano-TiO2 and TNTs based on the inactivation performance on Escherichia coli cells under simulated solar light and in a dark chamber, and their toxicity mechanisms were explored on a subcellular level. The inactivation performance was: nano-TiO2-solar (100.0%) > TNTs-solar (62.7%) > TNTs-dark (36.6%) > TiO2-dark (0.5%). The excellent inactivation performance of nano-TiO2 under solar light is caused by the large amount of active free radicals attacking cell organelles until peroxidation and death, which is due to the strong photocatalytic properties. The lower inactivation ability of nano-TiO2 in the dark was due to the absence of radicals and its accessible physical morphology. For TNTs, the inactivation ability under solar light is derived from a combination of its weak photocatalytic performance and morphological effects, and TNTs in a dark environment can only attack cells via physical piercing.
Liu W, Ji H, Chen L, Duan J.
Chapter 7 Application of Titanate Nanotubes for Water Treatment. In: Emerging Nanotechnologies for Water Treatment. The Royal Society of Chemistry; 2022. pp. 185-227.
访问链接AbstractTitanate nanotubes (TNTs), derived from TiO2 nanoparticles through hydrothermal treatment, have been attracting intensive research interests in recent years. Unlike the precursor TiO2 nanoparticles that have high photocatalytic activity under ultraviolet light, TNTs exhibit multi-layered and tubular structures. In addition, TNTs are composed of corrugated ribbons of edge-sharing [TiO6] octahedrons as the skeleton and H+/Na+ are located in the interlayers. Thus, TNTs usually have uniform tubular microstructures, large specific surface area, abundant functional groups (–ONa/–OH), good ion-exchange properties, high solution stability and high photoelectric quantum conversion effects. The specific physicochemical properties of TNTs indicate their great application potential in water and wastewater treatment. This chapter provides an overview of the latest research on the environmental applications and implications of TNTs. Conventional methods for the synthesis and characterization of TNTs are also summarized. TNTs and modified TNTs used as adsorbents, photocatalysts and catalysts for peroxymonosulfate/peroxydisulfate activation are systematically discussed. The environmental behaviors of aggregation and sedimentation of TNTs in water are also described.
Liu Y, Wang C-C, Liu W.
Emerging Nanotechnologies for Water Treatment. (
Liu Y, Wang C-C, Liu W). The Royal Society of Chemistry; 2022 pp. P001-542.
访问链接 Cai Z, Huang Y, Ji H, Liu W, Fu J, Sun X.
Type-II surface heterojunction of bismuth-rich Bi4O5Br2 on nitrogen-rich g-C3N5 nanosheets for efficient photocatalytic degradation of antibiotics. Separation and Purification Technology [Internet]. 2022;280:119772.
访问链接AbstractA novel g-C3N5/Bi4O5Br2 surface heterojunction was developed via in-situ growth of Bi-rich Bi4O5Br2 on g-C3N5 nanosheets. The optimal composite achieved 3.6- and 16.0- times of sulfathiazole (STZ) degradation activity when compared with pristine Bi4O5Br2 and g-C3N5. The interlayer stacking morphology and extra nitrogen in triazine units significantly narrowed the conduction band of g-C3N5, which greatly promoted its visible utilization; while the bismuth-rich property of Bi4O5Br2 prolonged the excited charge carrier lifetime. Both photoluminescence and electrochemical impedance spectroscopy analysis demonstrated that the type-II surface heterojunction (g-C3N5/Bi4O5Br2) offered remarkable charge transfer and separation due to the matched energy band structure. The STZ degradation mechanism and pathways were proposed based on experiments and density functional theory calculation, and the contribution of reactive species for STZ degradation followed the order of O2∙- > h+ > OH. Moreover, the toxicity evolution of STZ was evaluated, suggesting that sufficient mineralization is required to ensure safe discharge. The Box-Behnken experimental design methodology study revealed that g-C3N5/Bi4O5Br2 exhibited high reactivity for antibiotics degradation under different water matrix. This study suggested that g-C3N5/Bi4O5Br2 has great application potential for cost-effective remediation of persistent organic contaminants by using solar light.
Zong Y, Zhang H, Zhang X, Liu W, Xu L, Wu D.
High-valent cobalt-oxo species triggers hydroxyl radical for collaborative environmental decontamination. Applied Catalysis B: Environmental [Internet]. 2022;300:120722.
访问链接AbstractThe overlooked role of high-valent cobalt-oxo species (Co(IV)) in the Co(II)/peroxymonosulfate (PMS) process was uncovered recently using methyl phenyl sulfoxide (PMSO) as the probe. Herein, we further interestingly found that Co(IV) could trigger hydroxyl radical (•OH) formation, resulting in the oxidized products distribution of PMSO heavily relied on the relative concentration of PMSO. More significantly, the generation of a series of 18O-labeled hydroxylated products (i.e., hydroxylated methyl phenyl sulfone, nitrobenzene and 4-nitrobenzoic acid) in H218O conclusively verified that •OH was triggered by Co(IV) species. Density functional theory calculation demonstrated that Co(IV) initiated •OH formation via oxo ligand protonation-induced valence tautomerization. Moreover, the oxidative contribution of Co(IV) and •OH on organic degradation was specifically dependent on the type and concentration of the substrate. This study provided deeper insights into the evolution pathway of •OH mediated by Co(IV) species and enriched the understandings on the collaborative oxidation mechanism in Co(IV)-involved processes.
Wang Y, Song Y, Li N, Liu W, Yan B, Yu Y, Liang L, Chen G, Hou L’an, Wang S.
Tunable active sites on biogas digestate derived biochar for sulfanilamide degradation by peroxymonosulfate activation. Journal of Hazardous Materials [Internet]. 2022;421:126794.
访问链接AbstractConversion of digestate into biochar-based catalysts is an effective strategy for disposal and resource utilization. The active sites on biochar correlated with reactive species formation in peroxymonosulfate (PMS) system directly. Clarifying the structure-performance relationship of digestate derived biochar in PMS system was essential for decomposition of contaminants. Herein, dairy manure digestate derived biochar (DMDB) was prepared for PMS activation and sulfamethoxazole (SMX) degradation. The higher pyrolysis temperature could promote effective sites generation. Especially, the DMDB-800 catalyst exhibited excellent performance for PMS activation, achieving 90.2% degradation of SMX within 60 min. Based on the correlation analysis between log (k) values and active sites, defects, graphite N and CO were identified as dominant sites for PMS activation. The 1O2 oxidation and surface electron transfer were critical routes for SMX degradation. Besides, the degradation pathways of SMX were proposed according to DFT calculations and intermediates determination. The cleavage of the sulfonamide bond, hydroxylation of the benzene ring and oxidation of the amino group mainly occurred during SMX degradation. Overall, this study provides deep insights into the enhanced mechanism of tunable active sites on DMDBs for PMS activation, boosting the application of digestate biochar for water treatment in advanced oxidation systems.