Publications by authors named "Guoguang Liu"

81 Publications

Synchronous construction of a porous intramolecular D-A conjugated polymer via electron donors for superior photocatalytic decontamination.

J Hazard Mater 2021 Sep 29;424(Pt B):127379. Epub 2021 Sep 29.

School of Environmental Science and Engineering, Guangdong University of Technology, Guangzhou 510006, China. Electronic address:

The development of conjugated polymers with intramolecular donor-acceptor (D-A) units has the capacity to enhance the photocatalytic performance of carbon nitride (g-CN) for the removal of antibiotics from ambient ecosystems. This strategy addresses the challenge of narrowing the band gap of g-CN while maintaining its high LUMO position. For this study, we introduced the above donor units into g-CN to construct intramolecular D-A structures through the copolymerization of dicyandiamide with creatinine, which strategically extended light absorption into the green region and expedited photoelectron separation. The introduction of electron donor blocks kept the LUMO distributed on the melem, which maintained the high LUMO energy level of the copolymer with the potential to generate oxygen radicals. The as-prepared porous D-A conjugated polymer enhanced the photocatalytic degradation of sulfisoxazole with kinetic constants 5.6 times higher than that of g-CN under blue light and 15.3 times higher under green light. Furthermore, we surveyed the degradation mechanism including the effective active species and degradation pathways. This study offers a new perspective for the synchronous construction of a porous intramolecular D-A conjugated polymer to enhance water treatment and environmental remediation capacities.
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http://dx.doi.org/10.1016/j.jhazmat.2021.127379DOI Listing
September 2021

Superhigh co-adsorption of tetracycline and copper by the ultrathin g-CN modified graphene oxide hydrogels.

J Hazard Mater 2021 Sep 29;424(Pt B):127362. Epub 2021 Sep 29.

Guangzhou Key Laboratory Environmental Catalysis and Pollution Control, Guangdong Key Laboratory of Environmental Catalysis and Health Risk Control, School of Environmental Science and Engineering, Institute of Environmental Health and Pollution Control, Guangdong University of Technology, Guangzhou 510006, China.

Development of economic and efficient absorbent for the simultaneous removal of antibiotics and heavy metals is needed. In this study, a three-dimensional porous ultrathin g-CN (UCN) /graphene oxide (GO) hydrogel (UCN-GH) was prepared by co-assembling of UCN and GO nanosheets via the facile hydrothermal reaction. Characterizations indicated that the addition of UCN significantly decreased the reduction of CO and O-CO related groups of GO during the hydrothermal reaction and introduced amine groups on UCN-GH. The UCN-GH exhibited excellent ability on the co-removal of Cu(II) (q = 2.0-2.5 mmol g) and tetracycline (TC) (q = 1.2-3.0 mmol g) from water. The adsorption capacities were increased as UCN mass ratio increasing. The mutual effects between Cu(II) and TC were examined through adsorption kinetics and isotherm models. Characterizations and computational chemistry analysis indicated that Cu(II) is apt to coordinate with the amine groups on UCN than with oxygen groups on GO, which accounts for the enhanced adsorption ability of UCN-GH. In the binary system, Cu(II) acts as a bridge between TC and UCN-GH enhanced the removal of TC. The effects of pH and regular salt ions on the removal of Cu(II)/TC were examined. Moreover, the prepared UCN-GH also showed comparable co-adsorption capacities in practical water/wastewater.
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http://dx.doi.org/10.1016/j.jhazmat.2021.127362DOI Listing
September 2021

Effective stabilization of atomic hydrogen by Pd nanoparticles for rapid hexavalent chromium reduction and synchronous bisphenol A oxidation during the photoelectrocatalytic process.

J Hazard Mater 2021 Aug 20;422:126974. Epub 2021 Aug 20.

School of Environmental Science and Engineering, Guangdong University of Technology, Guangzhou 510006, China. Electronic address:

Atomic hydrogen (H*) plays a vital role in the synchronous redox of metallic ions and organic molecules. However, H* is extremely unstable as it is easily converted to hydrogen. Herein, we designed a novel strategy for the effective stabilization of H* to enhance its utility. The synthesized Pd nanoparticles grown on the defective MoS (DMS) of TiO nanowire arrays (TNA) (TNA/DMS/Pd) photocathode exhibited rapid Cr(VI) reduction (~95% in 10 min) and bisphenol A (BPA) oxidation (~97% in 30 min), with the kinetic constants almost 24- and 6-fold higher than those of the TNA photocathode, respectively. This superior performances could be attributed to: (i) the generated interface heterojunctions between TNA and DMS boosted the separation efficiencies of photogenerated electrons, thereby supplying abundant valance electrons to lower the overpotential to create a suitable microenvironment for H* generation; (ii) the stabilization of H* by Pd nanoparticles resulted in a significant increase in the yield of hydroxyl radical (•OH). This research provides a new strategy for the effective utilization of H* toward rapid reduction of heavy metals and synchronous oxidation of the refractory organics.
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http://dx.doi.org/10.1016/j.jhazmat.2021.126974DOI Listing
August 2021

Construction of double-functionalized g-CN heterojunction structure via optimized charge transfer for the synergistically enhanced photocatalytic degradation of sulfonamides and HO production.

J Hazard Mater 2021 Aug 10;422:126868. Epub 2021 Aug 10.

School of Environmental Science and Engineering, Guangdong University of Technology, Guangzhou 510006, China. Electronic address:

Herein, supporting g-CN embedded with benzene-ring (BCN) on P-modified g-CN (PCN) successfully synthesized the homogeneous photocatalyst BCN/PCN (PBCN) via a simple thermal polymerization reaction. Under blue-light (LED) irradiation, the optimized PBCN (0.448 min) demonstrated excellent photocatalytic performance, attaining over 74 times the degradation rate for sulfisoxazole (SSZ) in contrast to non-functionalized g-CN (CN, 0.006 min). Theoretical calculations revealed that the substitution of heterocyclic rings in the g-CN triazine networks with benzene-rings enabled them to serve as electron donors, while promoting photoinduced spatial charge dissociation. Further, the carrier PCN tended to serve as electron acceptors to form electron-rich corner-phosphorous sites. Reactive species experiments demonstrate that the O˙ and h constituted the primary photocatalytic mechanism of SSZ degradation. The potential SSZ degradation routes were predicted based on the transformation products via mass spectrometry. Finally, the composite materials also exhibited excellent photocatalytic activity in the conversion of solar energy to chemical energy (HO). This study guides the rational modification of g-CN-based semiconductors to achieve green energy production and beneficial ecological applications.
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http://dx.doi.org/10.1016/j.jhazmat.2021.126868DOI Listing
August 2021

Removal of lead ions by two FeMn oxide substrate adsorbents.

Sci Total Environ 2021 Jun 6;773:145670. Epub 2021 Feb 6.

School of Environmental Science and Engineering, Guangdong University of Technology, Guangzhou, Guangdong 510006, China.

Lead pollution has become a global concern due to its ubiquity and persistence. This study describes two FeMn oxide substrate adsorbents, namely, FeMn binary oxides (FMBO) and mesoporous FeMn binary oxide (MFMBO) covered with tannic acid film ([email protected] and [email protected]), for the treatment of Pb in water. The characterization results showed that TA was successfully coated onto the surfaces of FMBO and MFMBO. The maximum capacities of Pb on [email protected] and [email protected] were 322.08 and 357.14 mg g, respectively, which were twice those of FMBO and MFMBO. The adsorption of Pb on the adsorbents was a spontaneous, endothermic process with increasing disorder through thermodynamics studies. An overall mechanism was proposed for Pb adsorption, the improved adsorption performance of [email protected] and [email protected] is ascribed to the mesoporous characteristics and the introduction of hydroxyl groups. Further investigation indicated the adsorption of Pb could be attributed to electrostatic interactions on [email protected] and [email protected], and cation exchange existed through the formation of these internal surface complexes. The Pb-loaded adsorbents could be effectively desorbed in a dilute hydrochloric acid solution, promoting recycling and reuse of the regenerated adsorbents. These results warrant the promising application of [email protected] and [email protected] for the removal of Pb, and this work first proposed TA film-modified FMBO and MFMBO to improve its adsorption capacity in the application of environmental remediation.
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http://dx.doi.org/10.1016/j.scitotenv.2021.145670DOI Listing
June 2021

Interaction of graphene oxide with artificial cell membranes: Role of anionic phospholipid and cholesterol in nanoparticle attachment and membrane disruption.

Colloids Surf B Biointerfaces 2021 Jun 9;202:111685. Epub 2021 Mar 9.

State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing, Jiangsu 210023, China.

A mechanistic understanding of the interaction of graphene oxide (GO) with cell membranes is critical for predicting the biological effects of GO following accidental exposure and biomedical applications. We herein used a quartz crystal microbalance with dissipation monitoring (QCM-D) to probe the interaction of GO with model cell membranes modified with anionic lipids or cholesterol under biologically relevant conditions. The attachment efficiency of GO on supported lipid bilayers (SLBs) decreased with increasing anionic lipid content and was unchanged with varying cholesterol content. In addition, the incorporation of anionic lipids to the SLBs rendered the attachment of GO partially reversible upon a decrease in solution ionic strength. These results demonstrate the critical role of lipid bilayer surface charge in controlling GO attachment and release. We also employed the fluorescent dye leakage technique to quantify the role of anionic lipids and cholesterol in vesicle disruption caused by GO. Notably, we observed a linear correlation between the amount of dye leakage from the vesicles and the attachment efficiencies of GO on the SLBs, confirming that membrane disruption is preceded by GO attachment. This study highlights the non-negligible role of lipid bilayer composition in controlling the physicochemical interactions between cell membranes and GO.
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http://dx.doi.org/10.1016/j.colsurfb.2021.111685DOI Listing
June 2021

Integration of oxygen vacancies into BiOI via a facile alkaline earth ion-doping strategy for the enhanced photocatalytic performance toward indometacin remediation.

J Hazard Mater 2021 Jun 24;412:125147. Epub 2021 Jan 24.

School of Environmental Science and Engineering, Guangdong University of Technology, Guangzhou 510006, China. Electronic address:

Bismuth oxyiodide (BiOI) has garnered intense attention in the field of photocatalysis for environmental remediation; however, it suffers from a high electron-hole recombination rate. In this study, for the first time, we report on a facile strategy for the creation of oxygen vacancies in BiOI via strontium (Sr) doping. The as-prepared 0.45-SrBiOI demonstrated significantly enhanced photocatalytic degradation of indometacin under visible light exposure, which was almost 10 folds higher than pristine BiOI. This augmented photocatalytic performance was ascribed to the accelerated separation of charge carriers by oxygen vacancies, as well as Sr ion trapping electrons. Reactive species determination experiments revealed that O, O, and h were the dominant active species. Finally, potential indometacin degradation pathways were proposed based on the identification of degradation by-products and theoretical calculations. This study offers new perspectives for the synthesis of highly efficient and cost effective BiOI-based photocatalysts, and provides a promising strategy toward advanced environmental remediation.
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http://dx.doi.org/10.1016/j.jhazmat.2021.125147DOI Listing
June 2021

Scutellaria baicalensis Georgi polysaccharide ameliorates DSS-induced ulcerative colitis by improving intestinal barrier function and modulating gut microbiota.

Int J Biol Macromol 2021 Jan 4;166:1035-1045. Epub 2020 Nov 4.

School of Traditional Chinese Pharmacy, China Pharmaceutical University, Nanjing 211198, Jiangsu, PR China. Electronic address:

The aim of this study was to investigate the effect of a polysaccharide from Scutellaria baicalensis Georgi on UC. Gut microbiota dysbiosis is a worldwide problem associating with ulcerative colitis. One homogeneous polysaccharide, named SP2-1, was isolated from Scutellaria baicalensis Georgi. SP2-1 comprised mannose, ribose, rhamnose, glucuronic acid, glucose, xylose, arabinose, fucose in the molar ratio of 5.06:21.24:1.00:20.25:3.49:50.90:228.77:2.40, with Mw of 3.72 × 10 Da. SP2-1 treatment attenuated body weight loss, reduced DAI, ameliorated colonic pathological damage, and decreased MPO activity of UC mice induced by DSS. SP2-1 also suppressed the levels of proinflammatory cytokines. Additionally, the intestinal barrier was repaired due to the up-regulated expressions of ZO-1, Occludin and Claudin-5. SP2-1 remarkably enhanced the levels of acetic acid, propionic acid, and butyric acid in DSS-treated mice. Furthermore, as compared with model group, the abundance of Firmicutes, Bifidobacterium, Lactobacillus, and Roseburia were significantly increased with SP2-1 treatment. And SP2-1 could significantly inhibit the levels of Bacteroides, Proteobacteria and Staphylococcus. In conclusion, SP2-1 might serve as a novel drug candidate against UC.
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http://dx.doi.org/10.1016/j.ijbiomac.2020.10.259DOI Listing
January 2021

Defect-modified reduced graphitic carbon nitride (RCN) enhanced oxidation performance for photocatalytic degradation of diclofenac.

Chemosphere 2020 Nov 11;258:127343. Epub 2020 Jun 11.

School of Environmental Science and Engineering, Guangdong University of Technology, Guangzhou, 510006, China. Electronic address:

Hydroxyl radicals (OH) have robust non-selective oxidizing properties to effectively degrade organic pollutants. However, graphitic carbon nitride (g-CN) is restricted to directly generate OH due to its intrinsic valence band. In this study, we report a facile environmental-friendly self-modification strategy to synthesize reduced graphitic carbon nitride (RCN), with nitrogen vacancies and CN functional groups. The incorporation of CN enabled to downshift the valence band level, which endowed RCN with the capacity to directly generate OH via h. Experimental and instrumental analyses revealed the critical roles of nitrogen vacancies and CN groups in the modification of the RCN band structure to improve its visible light absorption and oxidizing capacity. With these superior properties, the RCN was significantly enhanced for the photocatalytic degradation of DCF under visible light irradiation. The self-modification strategy articulated in this study has strong potential for the creation of customized g-CN band structures with enhanced oxidation performance.
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http://dx.doi.org/10.1016/j.chemosphere.2020.127343DOI Listing
November 2020

Synthesis of a carbon dots modified g-CN/SnO Z-scheme photocatalyst with superior photocatalytic activity for PPCPs degradation under visible light irradiation.

J Hazard Mater 2021 01 21;401:123257. Epub 2020 Jun 21.

School of Environmental Science and Engineering, Guangdong University of Technology, Guangzhou, 510006, China. Electronic address:

As an emerging carbon nanomaterial, carbon dots (CDs) have superior prospects for applications in the area of photocatalysis due to their unique optical and electronic properties. In this study, a novel CDs modified g-CN/SnO photocatalyst (CDs/g-CN/ SnO) was successfully synthesized by the thermal polymerization. Under visible light irradiation, the resulting CDs/g-CN/SnO photocatalyst exhibited excellent photocatalytic activity for the degradation of indomethacin (IDM). It was demonstrated that a 0.5 % loading content of CDs led to the highest IDM degradation rate, which was 5.62 times higher than that of pristine g-CN. This improved photocatalytic activity might have been attributed to the unique up-conversion photoluminescence (PL) properties and efficient charge separation capacities of the CDs. Moreover, the combination of g-CN with SnO improved the separation of photoinduced carriers and augmented the specific surface area. Reactive species (RSs) scavenging experiments and electron spin resonance (ESR) revealed that superoxide radical anions (O) and photogenerated holes (h) played critical roles during the photocatalytic process. The results of the detection of HO and ESR confirmed that CDs/g-CN/ SnO was a Z-scheme heterojunction photocatalyst. Further, HRAM LC-MS/MS was employed to identify the byproducts of IDM, and the major IDM degradation pathways of the CDs/g-CN/SnO photocatalyst were proposed. This study provides new ideas for the design of novel CDs modified photocatalysts for environmental remediation.
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http://dx.doi.org/10.1016/j.jhazmat.2020.123257DOI Listing
January 2021

One-Step Synthesis of Hierarchical Flower-like SnO/BiOCOOH Microspheres with Enhanced Light Response for the Removal of Pollutants.

Langmuir 2020 08 20;36(30):9005-9013. Epub 2020 Jul 20.

Faculty of Environmental Science and Engineering, Guangdong University of Technology, Guangzhou 510006, PR China.

The low separation rate of electron-hole pairs in single-component photocatalysts severely limits their applications for wastewater treatment. For this study, SnO/BiOCOOH photocatalysts in flower-like microspheres were controllably synthesized via a one-step hydrothermal method and were characterized by various advanced techniques. These SnO/BiOCOOH nanocomposites demonstrated excellent photocatalytic activities for the degradation of rhodamine B (RhB), titan yellow, and levofloxacin hydrochloride (LVF). Specifically, 98.5% of RhB, 80% of titan yellow, and 85% of LVF were degraded under 5 W LED (λ = 365 nm) light irradiation within 30, 40, and 60 min, respectively. Radical trapping experiments and electron spin resonance results indicated that h was the dominant active radical, whereas ·O and ·OH played an auxiliary role in the photocatalytic system. Subsequently, a potential photocatalytic mechanism was proposed based on the experimental results.
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http://dx.doi.org/10.1021/acs.langmuir.0c00025DOI Listing
August 2020

Chemical identity and cardiovascular toxicity of hydrophobic organic components in PM.

Ecotoxicol Environ Saf 2020 Sep 11;201:110827. Epub 2020 Jun 11.

Guangzhou Key Laboratory of Environmental Catalysis and Pollution Control, Guangdong Key Laboratory of Environmental Catalysis and Health Risk Control, School of Environmental Science and Engineering, Institute of Environmental Health and Pollution Control, Guangdong University of Technology, Guangzhou, 510006, China; State Key Laboratory of Environmental and Biological Analysis, Department of Chemistry, Hong Kong Baptist University, Hong Kong, China. Electronic address:

Numerous experimental and epidemiological studies have demonstrated that exposure to PM may result in pathogenesis of several major cardiovascular diseases (CVDs), which can be attributed to the combined adverse effects induced by the complicated components of PM. Organic materials, which are major components of PM, contain thousands of chemicals, and most of them are environmental hazards. However, the contamination profile and contribution to overall toxicity of PM-bound organic components (OCs) have not been thoroughly evaluated yet. Herein, we aim to provide an overview of the literature on PM-bound hydrophobic OCs, with an emphasis on the chemical identity and reported impairments on the cardiovascular system, including the potential exposure routes and mechanisms. We first provide an update on the worldwide mass concentration and composition data of PM, and then, review the contamination profile of PM-bound hydrophobic OCs, including constitution, concentration, distribution, formation, source, and identification. In particular, the link between exposure to PM-bound hydrophobic OCs and CVDs and its possible underlying mechanisms are discussed to evaluate the possible risks of PM-bound hydrophobic OCs on the cardiovascular system and to provide suggestions for future studies.
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http://dx.doi.org/10.1016/j.ecoenv.2020.110827DOI Listing
September 2020

Efficient removal of triclosan via peroxymonosulfate activated by a ppb level dosage of Co(II) in water: Reaction kinetics, mechanisms and detoxification.

Ecotoxicol Environ Saf 2020 Jul 29;198:110676. Epub 2020 Apr 29.

State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing, 210023, PR China.

Triclosan (TCS), an extensively used broad-spectrum antimicrobial agent, has raised significant environmental concerns regarding its widespread occurrence in waters. In this study, the removal of TCS in aqueous solution via peroxymonosulfate (PMS) activated by an extremely low-level Co (0.02 μM) was systematically investigated. During preliminary test, TCS (10 μM) was totally degraded in 30 min by using 0.1 μM Co and 40 μM PMS at pH 7.0 with a degradation rate constant of 0.1219 min. A first-order apparent degradation rate of TCS was found with respect to the PMS concentrations. At extremely low dosage of Co (0.02 μM), the presence of NO, HCO, PLFA, and SRHA within test concentrations significantly inhibited TCS removal, while a dual effect of Cl on the degradation rate of TCS was observed. The quenching experiments verified that SO was the dominant reactive oxygen species (ROS) rather than OH. Six major intermediates were identified using TOF-LC-MS, based on which we proposed three associated reaction pathways including hydroxylation, ether bond breakage, and dechlorination. Toxicity predictions by ECOSAR software exhibited aquatic toxicity reduction of TCS after Co/PMS treatment. We outlook these findings to advance the feasibility of organic contaminants removal via Co/PMS system with Co at extremely low levels.
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http://dx.doi.org/10.1016/j.ecoenv.2020.110676DOI Listing
July 2020

Smart Removal of Dye Pollutants via Dark Adsorption and Light Desorption at Recyclable BiOCO Nanosheets Interface.

ACS Appl Mater Interfaces 2020 May 27;12(18):20490-20499. Epub 2020 Apr 27.

Centre for Clean Environment and Energy, School of Environment and Science, Gold Coast Campus, Griffith University, Queensland 4222, Australia.

The adsorbents for water treatment and purification are commonly not recyclable because of the lack of a reagent-less "switch" to readily release the adsorbed compounds. Herein, the interface of BiOCO (BOC) nanosheets is designed, synthesized, and modified with citric acid, namely, modified BiOCO (m-BOC). The m-BOC is able to selectively adsorb methylene blue (MB) in the dark and the adsorbed MB could be released in the light from m-BOC without the addition of any chemicals. The adsorption mechanism is attributed to the electrostatic attraction between positively charged MB and the negatively charged surface of m-BOC. In contrast, the desorption of MB has resulted from the photo-induced charge redistribution on the surface of m-BOC, which unlocks the coordination bond between m-BOC and the carboxylic group. As a result, BOC is recycled. Such a mechanism was verified by both experimental investigation and DFT calculation. This work provides a promising interfacial engineering strategy for the remediation of dye-polluted water and smart separation in chemical engineering.
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http://dx.doi.org/10.1021/acsami.0c02848DOI Listing
May 2020

Photochemical transformation of CN under UV irradiation: Implications for environmental fate and photocatalytic activity.

J Hazard Mater 2020 07 18;394:122557. Epub 2020 Mar 18.

Guangzhou Key Laboratory Environmental Catalysis and Pollution Control, Guangdong Key Laboratory of Environmental Catalysis and Health Risk Control, School of Environmental Science and Engineering, Institute of Environmental Health and Pollution Control, Guangdong University of Technology, Guangzhou 510006, China.

In this study, the photo-transformations of bulk CN (CN) and oxidized CN (OCN) under UV-irradiation were examined. Through NO release measurements, we found that the photo-transformation rate of OCN is higher than that of CN. Various characterization results revealed the structural and chemical properties changes of CN and OCN after photo-transformation. We proposed that under reactive oxygen species attack, CN and OCN were gradually broken into smaller fragments and finally mineralized into NO-, CO, and HO through the circular reactions of deamination-hydroxylation-decarboxylation. Through the zeta potential measurements and sedimentation experiments, the influence of photo-transformation on the water stabilities of CN and OCN were assessed. The stability of CN in water increased while the water stability of OCN decreased after photo-transformation, implying that the changes to CN-based materials caused by photo-transformation may significantly impact their environmental behaviors. Moreover, the photocatalytic activities of the photo-transformed OCN and CN substantially decreased, indicating that the structural changes might be the main reason for their photocatalytic activity loss. These findings highlight the non-negligible influence of photo-transformation on the fate of CN in aquatic environments, as well as on the photochemical stability during its use.
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http://dx.doi.org/10.1016/j.jhazmat.2020.122557DOI Listing
July 2020

GC-MS/MS analysis for source identification of emerging POPs in PM.

Ecotoxicol Environ Saf 2020 Apr 27;193:110368. Epub 2020 Feb 27.

Guangzhou Key Laboratory of Environmental Catalysis and Pollution Control, Guangdong Key Laboratory of Environmental Catalysis and Health Risk Control, School of Environmental Science and Engineering, Institute of Environmental Health and Pollution Control, Guangdong University of Technology, Guangzhou, 510006, China; State Key Laboratory of Environmental and Biological Analysis, Department of Chemistry, Hong Kong Baptist University, Hong Kong Special Administrative Region, China. Electronic address:

Emerging POPs have received increasing attention due to their potential persistence and toxicity, but thus far the report regarding the occurrence and distribution of these POPs in PM is limited. In this study, an extremely sensitive and reliable method, using ultrasonic solvent extraction and silica gel purification followed by gas chromatography coupled with electron ionization triple quadrupole mass spectrometry, was developed and used for the trace analysis of hexachlorobutadiene (HCBD), pentachloroanisole (PCA) and its analogs chlorobenzenes (CBs) in PM from Taiyuan within a whole year. The limits of detection and limits of quantitation of analytes were 1.14 × 10‒2.74 × 10 pg m and 3.80 × 10‒9.14 × 10 pg m. HCBD and PCA were detected at the mean concentrations of 3.69 and 1.84 pg m in PM, which is reported for the first time. Based on the results of statistical analysis, HCBD may come from the unintentional emission of manufacture or incineration of chlorinate-contained products but not coal combustion, while O-induced photoreaction was the potential source of PCA in PM. The temporal distributions of CBs in PM were closely related to coal-driven or agricultural activities. Accordingly, our study reveals the contamination profiles of emerging POPs in PM from Taiyuan.
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http://dx.doi.org/10.1016/j.ecoenv.2020.110368DOI Listing
April 2020

Ultrathin AgWO-coated P-doped g-CN nanosheets with remarkable photocatalytic performance for indomethacin degradation.

J Hazard Mater 2020 06 19;392:122355. Epub 2020 Feb 19.

School of Environmental Science and Engineering, Guangdong University of Technology, Guangzhou, 510006, China.

As a metal-free photocatalyst, the photocatalytic activity of graphitic carbon nitride (g-CN) remains restricted due to an insufficient visible-light absorption capacity, the rapid recombination of photoinduced carriers, and low surface area. Consequently, P-doped g-CN (PCN) was successfully prepared via a single -step thermal polymerization technique using phytic acid biomass and urea, which exhibited remarkable photocatalytic activity for the degradation of indometacin (IDM). The IDM degradation rate was 7.1 times greater than that of pristine g-CN (CN). Furthermore, AgWO was loaded onto the surface of the PCN, which formed a Z-scheme heterostructure that promoted the separation of photogenerated carriers. According to analyses of the chemical binding states of PCN, P atoms replaced carbon atoms in the CN framework. According to electron localization function analysis, the low ELF values of P-N facilitated the transfer of photoelectrons. The results of active species scavenging experiments confirmed that superoxide radicals were the primary active species in the photocatalytic degradation system. Finally, the photocatalytic degradation pathways of IDM were predicted through the identification of by-products and IDM reaction sites.
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http://dx.doi.org/10.1016/j.jhazmat.2020.122355DOI Listing
June 2020

Highly active metal-free carbon dots/g-CN hollow porous nanospheres for solar-light-driven PPCPs remediation: Mechanism insights, kinetics and effects of natural water matrices.

Water Res 2020 Apr 9;172:115492. Epub 2020 Jan 9.

School of Environmental Science and Engineering, Guangdong University of Technology, Guangzhou, 510006, China. Electronic address:

Pharmaceuticals and personal care products (PPCPs) are increasingly being scrutinized by the scientific community due to their environmental persistence. Therefore, the development of novel environmentally compatible and energy-efficient technologies for their removal is highly anticipated. In this work, a novel metal-free photocatalytic nanoreactor was successfully synthesized by anchoring carbon dots to hollow carbon nitride nanospheres (HCNS/CDs). The unique structure of these hollow nanospherical HCNS/CDs hybrids endowed them with a high population of reactive sites, while enhancing optical absorption due to internal light reflection. Simultaneously, the CDs served as "artificial antennas" to absorb and convert photons with low energy, due to their superior up-converting properties. Consequently, the HCNS/CDs demonstrated excellent photodegradation activities for the degradation of PPCPs under broad-spectrum irradiation. Remarkedly, 10 mg/L of naproxen (NPX) was completely degraded following 5 min of natural solar irradiation. It was further revealed that the O played a significant role during the photocatalytic process, which could lead to the decomposition of NPX. The effects of natural water matrices and the degradation of trace PPCPs further supported that this photocatalytic system may be efficaciously applied for the remediation of PPCPs contamination in ambient waterways.
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http://dx.doi.org/10.1016/j.watres.2020.115492DOI Listing
April 2020

UV-Induced Photodegradation of Naproxen Using a Nano γ-FeOOH Composite: Degradation Kinetics and Photocatalytic Mechanism.

Front Chem 2019 12;7:847. Epub 2019 Dec 12.

School of Environmental Science and Engineering, Guangdong University of Technology, Guangzhou, China.

Naproxen (NPX) is one of the most common pharmaceutical and personal care products found in surface water, which is recalcitrant to degradation by biological treatment or complete removal via traditional sewage treatment processes. In this study, nanoscale γ-FeOOH was synthesized and characterized by X-ray diffraction, scanning electron microscopy, surface analysis, and analysis of the forbidden bandwidth. Under UV irradiation, γ-FeOOH had the capacity to rapidly photodegrade NPX. The photodegradation rate of NPX was dependent on the concentration of γ-FeOOH in solution, initial NPX concentration, and pH. By increasing the concentration of γ-FeOOH, the NPX photodegradation rate was increased and then remained stable. Furthermore, the highest photodegradation rate for NPX was observed under acidic conditions. Through the analysis of the active substances (such as h, e, OH, O, and ) by electron spin resonance, the photocatalytic mechanism of NPX degradation on γ-FeOOH was determined to be semiconductor photocatalysis.
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http://dx.doi.org/10.3389/fchem.2019.00847DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6920245PMC
December 2019

A novel synthetic carbon and oxygen doped stalactite-like g-CN for broad-spectrum-driven indometacin degradation.

J Hazard Mater 2020 03 26;386:121961. Epub 2019 Dec 26.

School of Environmental Science and Engineering, Guangdong University of Technology, Guangzhou, 510006, China. Electronic address:

Achieving efficient solar utilization is a primary goal in the field of photocatalytic degradation of PPCPs. For this study, a broad-spectrum carbon and oxygen doped, porous g-CN (COCN) was synthesized via a simple co-pyrolysis of dicyandiamide and methylamine hydroiodide (CHN·HI). The 0.3COCN demonstrated an excellent photocatalytic degradation of indometacin (IDM), which was 5.9 times higher than bulk g-CN. The enhanced photocatalytic activity could be ascribed to the broad-spectrum utilization of solar light and improved charge separation efficiency. Reactive species (RSs) scavenging experiments have shown that O and O were the dominant active species. Further, the 0.3COCN exhibits excellent yield of hydroxyl radicals which was confirmed by electron spin resonance (ESR) spectra. Meanwhile, the degradation pathways of IDM were proposed according the HRAM LC-MS/MS and total organic carbon (TOC). This research provided a new strategy for a broad-spectrum photocatalyst, and a promising strategy for environmental remediation.
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http://dx.doi.org/10.1016/j.jhazmat.2019.121961DOI Listing
March 2020

A novel visible light controllable adsorption-desorption system with a magnetic recyclable adsorbent.

Sci Total Environ 2020 Mar 9;707:136025. Epub 2019 Dec 9.

Faculty of Environmental Science and Engineering, Guangdong University of Technology, Guangzhou 510006, PR China. Electronic address:

Convenient and energy-efficient desorption or regeneration processes are prerequisites for the development of an ideal adsorbent. For this work, a novel magnetic adsorbent (citric acid/BiOCO/FeO) was controllably synthesized via a facile hydrothermal method. The as-prepared materials demonstrated the excellent adsorption of methylene blue (MB), where ~70% of the MB was absorbed within 10 min. Interestingly, the desorption process could be triggered by visible light irradiation, and 99% of the absorbed MB was released into solution within 4 h. Further, the magnetic materials could be conveniently recovered using a magnet and regenerated via a model hydrothermal process. Even after two regeneration cycles, approximately 60% adsorption and 63% desorption abilities were retained, which suggested strong potential for the recyclability of these materials.
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http://dx.doi.org/10.1016/j.scitotenv.2019.136025DOI Listing
March 2020

FeO-assisted laser desorption ionization mass spectrometry for typical metabolite analysis and localization: Influencing factors, mechanisms, and environmental applications.

J Hazard Mater 2020 04 3;388:121817. Epub 2019 Dec 3.

Guangzhou Key Laboratory of Environmental Catalysis and Pollution Control, Guangdong Key Laboratory of Environmental Catalysis and Health Risk Control, School of Environmental Science and Engineering, Institute of Environmental Health and Pollution Control, Guangdong University of Technology, Guangzhou, 510006, China; State Key Laboratory of Environmental and Biological Analysis, Department of Chemistry, Hong Kong Baptist University, Hong Kong SAR, China. Electronic address:

FeO has been suggested as an efficient matrix for small-molecule analysis by laser desorption ionization mass spectrometry (LDI-MS), but thus far there has been no systematic study exploring the influencing factors of nano-FeO on the detection of typical metabolites, or the mechanism by which nano-FeO assists the desorption and ionization of analytes after receiving laser energy. In this study, FeO nanoparticles with different physicochemical properties were synthesized and characterized. The results revealed that smaller particle size and greater surface hydroxyl amount of nano-spherical FeO could improve the intensity and relative standard deviation of typical metabolites by LDI-MS. The thermally driven desorption process played a vital role in LDI performance, but the chemical interactions between nano-FeO and analytes did not. Good intra- or inter-spot repeatability and linearity of analytes were obtained by the optimum FeO-assisted LDI-MS. Finally, the developed method was successfully used for the rapid analysis and localization of endogenous metabolites in biofluids and whole zebrafish tissue section samples. Our results not only elucidate the influencing factors and mechanisms of nano-FeO for the detection of typical metabolites in LDI-MS but also reveal an innovative tool for the imaging of chemicals in the regions of interest in terms of eco-toxicological research.
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http://dx.doi.org/10.1016/j.jhazmat.2019.121817DOI Listing
April 2020

One-step synthesis of phosphorus/oxygen co-doped g-CN/anatase TiO Z-scheme photocatalyst for significantly enhanced visible-light photocatalysis degradation of enrofloxacin.

J Hazard Mater 2020 03 8;386:121634. Epub 2019 Nov 8.

School of Environmental Science and Engineering, Guangdong University of Technology, Guangzhou, 510006, China.

Anatase TiO nanoparticles coated with P and O co-doped g-CN were prepared via a single-step procedure. The resulting POCN/anatase TiO demonstrated remarkable performance in the degradation of enrofloxacin (ENFX). The photocatalytic activity of this heterojunction was 28.9 and 3.71 times better than that of the CN and anatase TiO, respectively. The microtopography of the POCN/anatase TiO was revealed in this study. Co-doping with P and O increased the visible light adsorption capacity of the g-CN, whereas the anatase TiO nanoparticles enhanced the adsorption properties of the ENFX and the separation of the photoinduced carriers of the POCN/anatase TiO. The O and h were the main reactive oxidative species in the photocatalytic degradation of ENFX. The results of the detection of HO and ESR confirmed that POCN/anatase TiO was a type Z-scheme photocatalyst. Finally, the ENFX degradation pathways were estimated through the detection of by-products.
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http://dx.doi.org/10.1016/j.jhazmat.2019.121634DOI Listing
March 2020

Phosphate-modified m-BiO enhances the absorption and photocatalytic activities of sulfonamide: Mechanism, reactive species, and reactive sites.

J Hazard Mater 2020 02 13;384:121443. Epub 2019 Oct 13.

School of Environmental Science and Engineering, Guangdong University of Technology, Guangzhou, 510006, China. Electronic address:

Widespread usage of the sulfonamide class of antibiotics is causing increasing ecotoxicological concern, as they have the capacity to alter ambient ecosystems. Photocatalytic technology is an attractive yet challenging strategy for the degradation of antibiotics. For this work, the phosphate modification of m-BiO (BiO-P) was prepared via a one-step hydrothermal process involving sodium bismuthate and sodium phosphate, which was employed for the degradation of sulfamethazine (SMZ) under visible light irradiation. The 0.5% BiO-P exhibited excellent photocatalytic performance, which was 1.9 times that of pure m-BiO. The photocatalytic degradation kinetics and mechanism of SMZ was investigated at different pH, whereupon it was revealed that m-BiO-P exhibited improved SMZ adsorption and photocatalytic activities in contrast to pure m-BiO. Compared with other four sulfonamide antibiotics, structures that contained additional methyl on the pyrimidine could be more easily attacked by phosphate modified m-BiO. Reactive species (RS) scavenging experiments revealed that h was primarily responsible for the degradation of SMZ. Further studies of RS by ESR technology, and the results of photoelectrochemical properties showed phosphate-modified m-BiO could make greater use of photogenerated carriers, thereby producing additional RS. Based on the HRAM LC-MS/MS and the Frontier Molecular Orbital Theory, the degradation pathways of SMZ were proposed.
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http://dx.doi.org/10.1016/j.jhazmat.2019.121443DOI Listing
February 2020

Activation of peroxymonosulfate by Fe doped g-CN /graphene under visible light irradiation for Trimethoprim degradation.

J Hazard Mater 2020 02 13;384:121435. Epub 2019 Oct 13.

School of Environmental Science and Engineering, Institute of Environmental Health and Pollution Control, Guangdong University of Technology, Guangzhou 510006, China. Electronic address:

Fe-doped g-CN / graphene (rGO) composites were investigated as catalysts for the activation of peroxymonosulfate (PMS) to degrade Trimethoprim (TMP) under visible light irradiation. The rapid recombination of photogenerated electron-hole pairs in g-CN may be suppressed by doping with Fe and incorporating rGO. The TMP degradation efficiency using 0.2% Fe-g-CN/2 wt% rGO/PMS was 3.8 times than that of g-CN/PMS. The degradation efficiency of TMP increased with higher catalyst dosages and PMS concentrations. Acidic condition (pH = 3) was observed to significantly enhance the TMP degradation efficiency from 61.4% at pH = 6 to nearly 100%. By quenching experiments and electron spin resonance (ESR), O was found to play an important role for the activation of PMS to accelerate the generation of reactive radicals for the TMP degradation. A total of 8 intermediates derived from hydroxylation, demethoxylation and carbonylation were identified through theoretical calculations and the HRAM/LC-MS-MS technique, and transformation pathways of TMP oxidation were proposed. TOC removal rate of TMP increased as reaction time was prolonged. Acute toxicity estimation by quantitative structure-active relationship analysis indicated that most of the less toxic intermediates were generated. The aim of this study was to elucidate and validate the functionality of a promising polymeric catalyst for the environmental remediation of organic contaminants.
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http://dx.doi.org/10.1016/j.jhazmat.2019.121435DOI Listing
February 2020

Evaluation and optimization of sample pretreatment for GC/MS-based metabolomics in embryonic zebrafish.

Talanta 2020 Jan 14;207:120260. Epub 2019 Aug 14.

Guangzhou Key Laboratory of Environmental Catalysis and Pollution Control, Guangdong Key Laboratory of Environmental Catalysis and Health Risk Control, School of Environmental Science and Engineering, Institute of Environmental Health and Pollution Control, Guangdong University of Technology, Guangzhou, 510006, China; State Key Laboratory of Environmental and Biological Analysis, Department of Chemistry, Hong Kong Baptist University, Hong Kong SAR, China. Electronic address:

Metabolomics tactics have been applied in the research associated with embryonic zebrafish. However, the report regarding the evaluation of impacts of sample pretreatment on metabolomics results from zebrafish embryos is limited. In the present study, different data normalization approaches, extraction solvents, and extraction strategies for off-line derivatization gas chromatography coupled with mass spectrometry-based metabolomics analysis of zebrafish eleutheroembryos were evaluated and optimized. The results showed that, when 4-chlorophenylalanine normalization, sample homogenization and pure methanol combined with ultrasonic extraction were conducted, better repeatabilities, higher signals and broader coverages of detected metabolites can be achieved. The recovery and standard deviation of most standards were in the range of 82%-121% and 6.6%-12%, respectively, while the relative standard deviation of major detected metabolites ranged from 5.4% to 19%, indicating good extraction efficiencies and method precision. Under the developed method, 87 important endogenous metabolites such as citric acid and hypoxanthine were identified by universal databases or standards among 270 extracted metabolites, which consisted of sugars, amines, amino acids, nucleotides, fatty acids, and sterols. Therefore, the results could provide a proper pretreatment protocol for the analysis of wide-coverage metabolome in embryonic zebrafish. In addition, this study highlights the impact of normalization and extraction methods on the data quality of metabolomics analysis.
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http://dx.doi.org/10.1016/j.talanta.2019.120260DOI Listing
January 2020

Transformation of atenolol by a laccase-mediator system: Efficiencies, effect of water constituents, and transformation pathways.

Ecotoxicol Environ Saf 2019 Nov 13;183:109555. Epub 2019 Aug 13.

Guangzhou Key Laboratory Environmental Catalysis and Pollution Control, Guangdong Key Laboratory of Environmental Catalysis and Health Risk Control, School of Environmental Science and Engineering, Institute of Environmental Health and Pollution Control, Guangdong University of Technology, Guangzhou, 510006, China.

In this study, we investigated the transformation of atenolol (ATL) by the naturally occurring laccase from Trametes versicolor in aqueous solution. Removal efficiency of ATL via laccase-catalyzed reaction in the presence of various laccase mediators was examined, and found that only the mediator 2, 2, 6, 6-tetramethyl-1-piperidinyloxy (TEMPO) was able to greatly promote ATL transformation. The influences of TEMPO concentration, laccase dosage, as well as solution pH and temperature on ATL transformation efficiency were tested. As TEMPO concentrations was increased from 0 to 2000 μM, ATL transformation efficiency first increased and then decreased, and the optimal TEMPO concentration was determined as 500 μM. ATL transformation efficiency was gradually increased with increasing laccase dosage. ATL transformation was highly pH-dependent with an optimum pH of 7.0, and it was almost constant over a temperature range of 25-50 °C. Humic acid inhibited ATL transformation through competition reaction with laccase. The presence of anions HCO and CO reduced ATL transformation due to both anions enhanced solution pHs, while Cl, SO, and NO at 10 mM showed no obvious influence. The main transformation products were identified, and the potential transformation pathways were proposed. After enzymatic treatment, the toxicity of ATL and TEMPO mixtures was greatly reduced. The results of this study might present an alternative clean strategy for the remediation of ATL contaminated water matrix.
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http://dx.doi.org/10.1016/j.ecoenv.2019.109555DOI Listing
November 2019

Degradation of propranolol by UV-activated persulfate oxidation: Reaction kinetics, mechanisms, reactive sites, transformation pathways and Gaussian calculation.

Sci Total Environ 2019 Nov 6;690:878-890. Epub 2019 Jul 6.

School of Environmental Science and Engineering, Guangdong University of Technology, Guangzhou 510006, China. Electronic address:

Contamination with β-blockers such as propranolol (PRO) poses a potential threat to human health and ecological system. The present study investigated the kinetics and mechanisms of PRO degradation by UV-activated persulfate (UV/PS) oxidation. Here, the experimental results showed that the degradation of PRO followed pseudo-first-order reaction kinetics, the degradation rate constant (k) was increased dramatically with increasing PS dosage or decreasing initial PRO concentration. And increasing the initial solution pH could also enhance the degradation efficiency of PRO. Radical scavenging experiments demonstrated that the main radical species was sulfate radicals (SO), with hydroxyl radicals (HO·) playing a less important role. Meanwhile, the second-order rate constants of PRO degradation with SO and HO· were determined to be 1.94 × 10 M s and 6.77 × 10 M s, respectively. In addition, the presence of natural organic matter (NOM) and nitrate anion (NO) showed inhibitory effect on PRO degradation, whereas bicarbonate anion (HCO) and chlorine anion (Cl) greatly enhanced the degradation of PRO. Moreover, the transformation products of PRO were identified by applying ultra performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry (UPLC/Q-TOF-MS) technique. Molecular orbital calculations were used to estimate the reaction site of PRO with radicals, simultaneously. Hence, the transformation pathways including hydroxylation, dehydration, naphthalene ring opening, and the cleavage of aldehyde groups were proposed. This work enriches the mechanism of PRO degradation under UV/PS system on the basis of results obtained by experimental characterization and Gaussian theoretical calculation.
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http://dx.doi.org/10.1016/j.scitotenv.2019.07.034DOI Listing
November 2019

Enhanced Cu(II)-mediated fenton-like oxidation of antimicrobials in bicarbonate aqueous solution: Kinetics, mechanism and toxicity evaluation.

Environ Pollut 2019 Sep 29;252(Pt B):1933-1941. Epub 2019 May 29.

State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing, 210023, People's Republic of China. Electronic address:

Increasing attention has been attracted in developing new technologies to remove chlorofene (CF) and dichlorofene (DCF), which were active agents in antimicrobials for general cleaning and disinfecting. This study investigated the significant influences of bicarbonate (HCO) on the degradation of CF and DCF in the Cu(II)-mediated Fenton-like system Cu/HO. Our results indicate that HCO may play a dual role to act 1) as a ligand to stabilize Cu(II), forming soluble [Cu(HCO)(S)] species to catalyze HO producing hydroxyl radical (OH) and superoxide ion (O) and 2) as a OH scavenger. Furthermore, the reaction kinetics, mechanisms, and intermediates of CF and DCF were assessed. The apparent rate constants of CF and DCF were enhanced by a factor of 8.5 and 5.5, respectively, in the presence of HCO at the optimized concentration of 4 mM. Based on the intermediate identification and frontier electron densities (FEDs) calculations, the associated reaction pathways were tentatively proposed, including C-C scission, single or multiple hydroxylation, and coupling reaction. In addition, significant reduction in the aquatic toxicity of CF and DCF was observed after treatment with Cu/HO-HCO system, evaluated by Ecological Structure Activity Relationships (ECOSAR) program. These findings provide new insights into Cu(II)-mediated reactions to better understand the environmental fate of organic contaminants in carbonate-rich waters.
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http://dx.doi.org/10.1016/j.envpol.2019.05.148DOI Listing
September 2019

Degradation of triphenyl phosphate (TPhP) by CoFeO-activated peroxymonosulfate oxidation process: Kinetics, pathways, and mechanisms.

Sci Total Environ 2019 Sep 9;681:331-338. Epub 2019 May 9.

Guangzhou Key Laboratory Environmental Catalysis and Pollution Control, Guangdong Key Laboratory of Environmental Catalysis and Health Risk Control, School of Environmental Science and Engineering, Institute of Environmental Health and Pollution Control, Guangdong University of Technology, Guangzhou 510006, China.

The aryl organophosphate flame retardant triphenyl phosphate (TPhP) has been frequently detected in environment and biota, and the potential risks of TPhP to aquatic organisms have also been demonstrated. The degradation of TPhP by CoFeO activated peroxymonosulfate (PMS) was studied in this work. At initial pH of 7.0, 10 μM TPhP could be removed by 99.5% with 0.25 g/L CoFeO and 0.5 mM PMS after 6 min oxidation, indicating the excellent performance of CoFeO activated PMS process on the treatment of TPhP. The influence of PMS and CoFeO dosage, initial pH, humic acid (HA), and anions (Cl, NO, and HCO) on TPhP degradation were investigated systematically. Results showed that the degradation of TPhP was enhanced with increasing PMS concentrations from 0.1 to 1 mM, while it reduced as CoFeO dosage increased. TPhP degradation efficiencies depended on solution pH with neutral pH showing the optimum degradation conditions. Recycling experiment indicated that the CoFeO nanoparticles (NPs) possessed high potential for reusability. The radical identification experiments were performed and SO• was confirmed as the dominant radicals in TPhP degradation, and activation mechanism of PMS by CoFeO NPs was hence explained. Humic acids (HA) (2-20 mg/L) as the representative organic natural matter existing in environment inhibited TPhP removal. Anions including Cl, NO, and HCO all reduced TPhP degradation. In addition, TPhP degradation products were identified by liquid chromatography-mass spectrometry, and the degradation pathways of TPhP were proposed accordingly.
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http://dx.doi.org/10.1016/j.scitotenv.2019.05.105DOI Listing
September 2019
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