Peroxydisulfate Activation Research Articles

Visible light-driven Cl-g-C3N4 activated peroxydisulfate process for TMP efficient degradation in a wide pH range

A narrow pH-applicability range can impact the actual treatment efficiency of AOPs, so the application of a wide pH range in AOP technology has garnered significant attention. In this study, the Cl-doped g-C3N4 as a visible light catalyst to activate the peroxydisulfate (PDS) process, named Vis/Cl-g-C3N4/PDS, was developed for trimethoprim (TMP) degradation in a wide pH range of 3–11. Results show that the Vis/Cl-g-C3N4/PDS process exhibited degradation efficiencies for TMP that were 1.39 times and 7.74 times higher than those of the Vis/Cl-g-C3N4 process and the Vis/g-C3N4 process, respectively. The Vis/Cl-g-C3N4/PDS process perfectly achieved degradation rates of over 98 % for TMP within a wide pH range of 3–11. It concluded that the high efficiency of the Vis/Cl-g-C3N4/PDS process in degrading TMP over a wide pH range was caused by the two co-existing reactive oxygen species (ROS) generation mechanism pathways: the photocatalytic activation of PDS and the light-assisted hydrolysis of PDS. Moreover, after 3 h of illumination in the Vis/Cl-g-C3N4/PDS process, a degradation range of 85.7 %–97.8 % was demonstrated in various real water matrices including of tap water, secondary sedimentation tank effluent, surface water, and aquaculture water. This study provided practical significance for the practical application of AOPs in water environmental pollution control.

Enhanced levofloxacin degradation through efficient activation of peroxymonosulfate using N-doped bulged multilayer Graphene: Harnessing interface structure to regulate carrier concentration and transport speed

Nitrogen (N)-doped carbon materials are regarded as potential catalysts for advanced oxidation procedures due to their efficiency and environmentally friendly nature. Nevertheless, the low carrier concentration, slow charge transfer, and limited mass transfer efficiency hinder satisfactory catalytic performance. Herein, we present the novel use of graphite nanosheets as precursors to synthesize nanoporous N-doped mesoporous expanded and bulged multilayer graphene (EG@N-x) with varying proportions for peroxydisulfate (PMS) activation. The EG@N-2.5 catalyst demonstrates a degradation rate of 0.140 min−1, and over 90 % of LEVO (24 mg/L) was decomposed in 10 min. Additionally, the EG@N-2.5/PMS system possessed a broad pH range of efficiency (1.0–7.0), exceptional anti-interference performance against anions and humic acid (HA), and marvelous reusability, which can be attributed to the superior PMS activation performance of EG@N-x by lowering the EHOMO − ELUMO (EPD = 0.014433) gap, and reducing the adsorption binding energy (Eads = -2.33 eV), enhancing the amount of charge transfer (Q = 0.6190 e) in the EG@N-x/PMS system. The removal of LEVO is primarily attributed to the mechanism of singlet oxygen (1O2) mechanism and the metastable reactive complexes in electron transfer. Decarboxylation, defluorination, and depiperazinylation are three dominant reaction pathways. Moreover, the EG@N-x/PMS system demonstrates adequate mineralization of LEVO under various organic and environmental conditions, reducing effluent biotoxicity.

Constructing a Z-Scheme Co3O4/BiOBr Heterojunction to Enhance Photocatalytic Peroxydisulfate Oxidation of High-Concentration Rhodamine B: Mechanism, Degradation Pathways, and Toxicological Evaluations.

Photocatalytic coupling technologies have emerged as popular strategies to increase the treatment efficiency of dye-containing wastewater. Herein, the Z-scheme Co3O4/BiOBr heterojunction (Z-CBH) was constructed and developed as a photocatalytic peroxydisulfate (PDS) activator for the degradation of high-concentration Rhodamine B (RhB). Multiple testing techniques were employed to confirm the formation of Z-CBHs. When 0.1 g·L-1 of Z-CBH20 and 1.0 mmol·L-1 of PDS were added simultaneously under simulated sunlight irradiation, the RhB degradation efficiency could approach 91.3%. Its reaction rate constant (0.01231 min-1) was much beyond the sum of those in the Z-CBH20/light system (0.00436 min-1) and the PDS/light system (0.0062 min-1). h+, •OH, •O2-, SO4•-, and 1O2 were detected as the dominant reactive species for RhB degradation. The potential mechanism of photocatalytic PDS oxidation was proposed. The possible intermediates were determined by high-performance liquid chromatography-quadrupole time-of-flight mass spectrometry assisted with density functional theory and Fukui theory. The possible degradation pathways of RhB degradation were put forward. The toxicological properties of RhB and its intermediates were evaluated by quantitative structure-activity relationship prediction. This work will not only provide a reference for developing photocatalytic persulfate activators but also gain an insight into the degradation pathways of RhB and the toxicity of its intermediates.

Magnetic catalysts of MnFe2O4-AC activated peroxydisulfate for high-efficient treatment of norfloxacin wastewater

Norfloxacin (NOR) wastewater with a significant corrosive effect on human tissues requires deep treatment before discharge. Peroxydisulfate (PDS) activation with catalysts is an effective advanced method for wastewater treatment, and the key to its success lies in the design, synthesis, and preparation of efficient, stable, and easily prepared catalysts. In this study, magnetic catalysts of MnFe2O4-AC were synthesized through the hydrothermal method as the basic material activated PDS. The crystal structures were characterized using various techniques, including SEM-EDS, XRD, FT-IR, and XPS. The high magnetic properties of the prepared catalysts made them easily recoverable after wastewater treatment. In addition, the study investigated the effects of operating conditions on the treatment of NOR wastewater within the Electrochemistry/MnFe2O4-AC/PDS (EC/MnFe2O4-AC/PDS) system. Under the optimal conditions of current intensity of 0.15 A, catalyst dosage of 0.100 g/L, PDS concentration of 10 mmol/L, and NOR concentration of 5 mg/L, the removal rate of NOR was 97.33 %. The increased specific surface area of MnFe2O4-AC catalysts, when compared to MnFe2O4 catalysts, benefited the activation of PDS. MnFe2O4-AC catalysts showed a good stability in activating PDS for NOR wastewater treatment without causing secondary pollution in repeated use experiments. Finally, the NOR degradation was attributed to both the generation of free radicals (SO4•- and ‧OH radicals) and non-radical processes (electrode oxidation).

Iron-decorated covalent organic framework as efficient catalyst for activating peroxydisulfate to degrade 2,4-dichlorophenol: Performance and mechanism insight

Herein, a novel two-dimensional double-pore covalent organic framework (JLNU-305) was synthesized using N,N,N',N'-tetrakis(4-aminophenyl)-1,4-phenylenediamine (TAPD) and 2,2′-bipyridine-5,5′-dicarboxaldehyde (BPDA). The extended π-π conjugated structure and nitrogen-riched pyridine in JLNU-305 (JLNU = Jilin Normal University) provide abundant binding sites for Fe doping. The obtained JLNU-305-Fe exhibited high and recycled catalytic efficiency for peroxydisulfate (PDS) activation to completely degrade 10 mg/L 2,4-dichlorophenol (2,4-DCP) within 8 min. The JLNU-305-Fe/PDS system showed excellent catalytic activity and cyclic stability. The capture experiments and electron paramagnetic resonance (ESR) analysis indicated that the catalytic behavior of JLNU-305-Fe/PDS is contributed to the synergistic effect between free radicals and non-free radicals. It is the first time to activate PDS for covalent organic frameworks (COFs) being used to degrade 2,4-DCP, which has a great potential for development and practical application in related water environment remediation.

Peroxydisulfate activation by magnetic nanoflakes zero-valent iron/graphitized carbon composites for norfloxacin removal: Synergistic effect of 1O2 with surface Fe(IV)

The recycling and utilization of waste biomass resources have attracted widespread attention due to their enormous potential economic value. In this study, a magnetic zero-valent iron nanoflake-modified graphitic mesoporous carbon composite (Fe@SBCx) was prepared using ultrasound-assisted impregnation and pyrolysis strategies, and employed as an efficient peroxydisulfate (PDS) activator for the removal of the antibiotic norfloxacin (NOR) from water. The Fe@SBC1.13/PDS system exhibited excellent oxidation performance, achieving nearly complete removal (>99 %) of 10 mg/L NOR within 25 min. Singlet oxygen (1O2) and ferryl iron species (Fe(IV)) were identified as the major oxidative reactive species in the system. The formation of electron donor–acceptor complexes during the reaction facilitated the decomposition of PDS and the generation of oxidative species. Fe@SBC1.13 demonstrated satisfactory recyclability and catalytic stability. Based on density functional theory (DFT) calculations and intermediate product analysis, the degradation pathways of NOR were proposed. Moreover, the toxicity evaluation results revealed a lower bacterial cytotoxicity in the treated drainage. Overall, this study not only enriches the theoretical research on the degradation mechanisms of fluoroquinolone antibiotics in the environment but also provides a viable approach for developing highly efficient and carbon–neutral catalysts.

Cr and N co-doped biochar driving controllable peroxydisulfate activation pathways to degrade tetracycline: Pyrrolic N inducing singlet oxygen generation

Efficiently inducing nonradical pathway in peroxydisulfate (PDS) activation is promising in environmental decontamination due to the oxidation selectivity and anti-interference ability, but still remains challenges, e.g., low efficiency and high cost. In this study, a series of Cr and N co-doped biochar (Cr-N/BC) was synthesized via pyrolysis by using melamine-retanned chrome shaving (MCS) as precursors, to activate PDS toward the tetracycline (TC) degradation. The introduction of pyrrolic N on Cr-N/BC not only boosted the catalyst reactivity, but also altered the complexation state of PDS, thus triggering a shift in oxidative modes from the radical pathway into a singlet oxygen (1O2) dominated nonradical pathway, in which, the relative contribution of the nonradical oxidation to the TC degradation increased from 0 to 98%. Structure-activity relationship determination unveiled that pyrrolic N on Cr-N/BC surface greatly changed the charge distribution and chemical property of biochar, thereby facilitating the decomposition of PDS and generation of 1O2. In addition, ecotoxicological safety of the intermediates of TC in the 1O2-dominated pathway was evaluated to validate the superiority of the nonradical process. This study advances our understanding of designing reaction-oriented nonradical carbon-catalysis for selective decontamination.

Synergistic removal of sulphur-containing malodourous gases via peroxydisulfate activation in three-dimensional electrode system

A novel technology for peroxydisulfate (PDS) activation in a three-dimensional electrode system (3DES) was employed to purify sulphur-containing malodourous gases; the technical parameters of the process were optimised and the pathway of sulphur-containing malodourous substances was investigated. In 3DES, reactive substances such as SO4• ˉ, 1O2, and •OH were markedly higher, the SO4• ˉ radicals played a significant role in the context of sulphur-containing malodourous gases, and the conversion of CH3SH and CS2 was more complete. The CH3SH in the inlet gas was completely removed within 180 min, the CS2 removal was approximately 100% before 60 min, and it then tended to decline gradually. As H2S and NH3 coexisted in the inlet gas, there was no significant effect on odour removal, and the discarded absorption solution could be used to prepare nitrogen fertiliser as the efficiency of odour removal decreased. The particle electrode in 3DES not only promoted the transfer of insoluble gases into the absorption solution but also enhanced PDS activation. Consequently, the catalytic oxidation performance was greatly improved. A conversion pathway was proposed to explain the transformation of sulphur-containing components such as CH3SH and CS2. This study provides new insights for the removal of malodourous pollutants.

Readily triggered activation of peroxydisulfate by three-dimensional graphene for oxidation of organic compounds: A nonradical-led mechanism involving preferred Lewis basic sites

Nonradical advanced oxidation has a distinctive excellent selectivity and reactivity. The fine-tuned O/N basic functional groups play a distinguishing role in the occurrence of nonradical pathways. However, it remains debatable regarding the principal basic species and their contribution. Consequently, identification of preferred basic sites and the correlation with the triggered activation mechanism need to be further clarified. In this study, the hydrothermal and thermal annealing method were adopted to construct heterogeneous basic sites on three-dimensional graphene (3D GN), and the activity of peroxydisulfate (PDS) activation was systematically assessed by humic acid(HA)abatement. Herein, the significantly improved catalytic capability (up to 80 %) of 3D GN-NH3⋅H2O was acquired, more than 2 times compared to that of 3D GN-NH3. The added I D/I G value of 3D GN-NH3⋅H2O from 1.05 of 3D GN to 1.08 indicated that it is less graphitized and has more structural defects. Notably, the hydrothermal modification of NH3⋅H2O enhanced both the basic oxygen and nitrogen groups (C = O/pyrrolic-N, pyridine-N). A positive correlation was displayed between the integrated basic sites ratio (34.2–71.7 %) and reaction rate (0.169–0.442 min−1) based on quantitative calculation. Moreover, the increased content of basic sites and defective sites on 3D GN-NH3⋅H2O was responsible for the hydrophobic interaction and 1O2 generated in nonradical pathways. The most reactive basic site is the pyrrolic-N which was illustrated by density functional theory (DFT) calculations. Furthermore, a possibly involved nonradical activation mechanism of 3D GNs/PDS was explored. The challenges and prospects of PDS advanced oxidation activated by carbon catalyst are evaluated. This work provides insights into a facile protocol for engineering a carbon catalyst to drive efficient PDS activation in the remediation of water environmental pollutants.

Enhanced Peroxydisulfate (PDS) Activation for Sulfamethoxazole (SMX) Degradation by Modified Sludge Biochar: Focusing on the Role of Functional Groups

Modified sludge biochar, recognized for its notable economic and environmental benefits, demonstrates potential as an effective catalyst for peroxydisulfate (PDS) activation. Nevertheless, the specific mechanisms underlying its catalytic performance require more comprehensive investigation. In this study, a modified biochar (TSBC) doped with oxygen (O) and nitrogen (N) atoms was synthesized from sewage sludge and tannin extract, which significantly enhanced the activation of PDS for the degradation of sulfamethoxazole (SMX). The TSBC/PDS system demonstrated robust performance for SMX degradation, achieving over 90% efficiency over a wide pH range (3–10). Subsequent quenching experiments demonstrated that TSBC predominantly catalyzed PDS to generate O21, which effectively degraded SMX via a non-radical pathway. The O- and N-containing functional groups in TSBC were identified as the primary catalytic sites. Besides, density functional theory (DFT) calculations revealed that the incorporation of graphitic N significantly improved the adsorption capacity of PDS on the TSBC surface. Furthermore, based on the identification of intermediates and theoretical calculations, SMX was degraded mainly by two different pathways: S-N cleavage and O21 oxidation. This study offers a foundational framework for the targeted modification of sludge biochar, thereby expanding its applications.

Peroxydisulfate Activation by Carbon Materials for the Degradation of the Herbicide Ametryn in Waters.

Brazil, the largest global sugar cane producer, utilizes approximately 10 million hectares for cultivation. However, the increased use of agrochemicals in this industry raises concerns about environmental and human health impacts. Inclusively, ametryn (AMT), a pesticide intensively used in sugar cane plantations, has been detected in several water matrices at concerning levels, which evidences the urgent need for the development of technologies capable of removing this pesticide from the environment. This study investigated the removal efficiency of AMT from aquatic environments via oxidation promoted by persulfate (PS) activation mediated by carbon-based materials, such as graphene, carbon nanotubes, and activated carbon. Granular activated carbon (GAC) emerged as the most suitable material due to its clear catalytic role. A central composite design was used to evaluate and optimize the factors influencing AMT degradation and mineralization, revealing that the initial PS concentration and GAC dosage strongly impact the degradation rate and organic carbon removal in different directions. GAC was submitted to surface functionalization with N- and O-precursors to investigate how this impacts PS activation, and positive enhancements were noted with the latter, with a mineralization degree 9% superior. Experiments with real water matrices evidence the impact of other water constituents on the degradation rate of the target pollutant (k'300), which was reduced by half when performed in groundwater. Notwithstanding, the system still demonstrated a consistent capacity to remove organic content, ranging from 60 to 50% TOCremoval, regardless of the water matrix, indicating that the system might be effective in real contamination scenarios. This research highlights the potential of GAC and its modified version for remediation of AMT-contaminated water remediation.

Zr−Doped OMS−2 Nano−rods as Efficient Catalysts for Degradation of Tetracycline via Peroxydisulfate Activation

Zr−Doped OMS−2 Nano−rods as Efficient Catalysts for Degradation of Tetracycline via Peroxydisulfate Activation

Nitrogen self-doped Chlorella biochar as a peroxydisulfate activator for sulfamethazine degradation: The dominant role of electron transfer

Nitrogen-doped biochar has been proven to be an advantageous peroxodisulfate (PDS) activator. However, few studies on PDS activation by biochar prepared from biomass containing intrinsic nitrogen have been reported, and the performance and mechanism are still unclear. In this study, nitrogen self-doped Chlorella biochar (NCB) was prepared by pyrolysis. The results showed that the increase of pyrolysis temperature promoted the formation of graphitic structure in NCB, and the biochar prepared at 900 °C (NCB-900) had the best performance in activating PDS for sulfamethazine (SMZ) degradation. The NCB-900/PDS system had a wide pH applicability and excellent resistance to anion interference, as well as excellent performance in applications such as groundwater remediation. It was suggested that the graphitic nitrogen structures were the main active sites, and the sp2-hybridized graphitic carbon network was favorable for surface electron transfer in the redox reactions on the NCB-900 surface. The degradation mechanism was thoroughly investigated by electron paramagnetic resonance (EPR) test, quenching experiments, chemical probes, electrochemical measurements, and in situ Raman analysis. Rather than free radicals and singlet oxygen (1O2), surface electron transfer mediated by the NCB-900–PDS* complex dominated SMZ degradation in the NCB-900/PDS system.

The non-radical, non-ROS, and non-Cu(III) oxidation of inert pollutants significantly enhanced by CuO-MgO composites

Peroxydisulfate (PDS) is an appealing oxidant to eliminate water pollutants due to the relatively low cost and high stability compared with other peroxides. It needs to be activated for application, with non-radical producing processes being specifically preferred to obtain high selectivity and to reduce useless consumption of active species by ubiquitous chloride ions. Unfortunately, most of the current non-radical oxidation processes of PDS are ineffective toward inert pollutants. Here we report a novel non-radical PDS oxidation process initiated by CuO-MgO composites toward effective removing refractory iodinated contrast media compounds (ICMs). The optimized CuO-MgO composite was 18-times more efficient than CuO in activating PDS to remove iopamidol, a typical refractory ICM, and exhibited much lower Cu2+ leaching. Interestingly, the enhanced oxidation is not related to radicals, reactive oxygen species (ROS), or high valent Cu(III). We revealed with a series of surface characterization and density functional theory calculation that the CuO-MgO composite has Cu2+-Mg2+ heterojunctions of high electron density, thus is more active than CuO alone for PDS activation. PDS interacted with the composite surface in inner-sphere mode; consequently, the surface-bound PDS abstracted electrons directly from inert pollutants. Due to the lower oxidation power than traditional radicals, PDS/CuO-MgO oxidation of the ICM probe was insensitive to chloride and produced less hydroxyl- and nitro- degradation products. This research highlights that Cu2+-Mg2+ heterojunctions can play an important role in enhancing the non-radical and non-ROS oxidation capability of PDS toward inert pollutants.

Incorporation of N-doped biochar into submicron zero-valent iron for efficient peroxydisulfate activation in soil remediation: Performance and mechanism

The development of strategic methods to enhance the catalytic reactivity and electron efficiency of biochar-modified zero-valent iron (BC-ZVI) via mechanochemistry is highly important and desirable for the use of peroxydisulfate-based advanced oxidation processes (PDS-AOPs) in soil remediation. Herein, novel amphiphilic ball-milled N-doped biochar-ZVI composites (NBC-ZVIbm) were fabricated to activate PDS for efficient pyrene degradation in soil. The N-doped site- and alloying heterojunction-induced surface charge redistribution, directional electron transfer, and amphiphilicity of NBC-ZVIbm were verified, all of which improved the interactions among NBC-ZVIbm, PDS and pyrene. Specifically, NBC incorporation optimized PDS oxidation and pyrene adsorption on NBC-ZVIbm, forming a reaction center that efficiently accelerated the reaction. As a result, 95.5 % of 98.3 mg/kg pyrene in soil was degraded by NBC-ZVIbm/PDS within 7 d, which was 2.3 and 1.5 times greater than that of ball-milled ZVI and BC-ZVIbm, respectively; additionally, the electron efficiency of this process increased to 85.2 %. Characterization of the reaction process suggested that NBC incorporation induced directional electron transfer from ZVI to NBC for PDS activation and SO4•- generation. Subsequently, the amphiphilicity of NBC-ZVIbm promoted soil phase-pyrene desorption and migration, thereby increasing pyrene degradation. This NBC-incorporation method provides a strategy for constructing highly efficient ZVI-based catalysts for the use of PDS-AOPs in soil remediation.

Tunneling Electron-Mediated Electrochemical Activation of Peroxydisulfate for the Removal of Refractory Pollutants

Tunneling Electron-Mediated Electrochemical Activation of Peroxydisulfate for the Removal of Refractory Pollutants

Rational regulation of the electronic structure of Cu1 sites catalyst to modulate persulphate activation pathway

Single-atom CuN4 catalyst have demonstrated excellent efficiency by producing 100 % singlet oxygen (1O2) in persulfate activation system. However, 1O2-based nonradical system may not provide satisfying efficiency in refractory organic pollutants removal. Herein, we report that the bottleneck can be well tackled by refining the peroxydisulfate activation pathway in advanced oxidation processes (AOPs) via manipulating the electron structure of the catalysts. As expected, the resulting Cu-N3O with optimized electronic structure can efficiently activate peroxydisulfate (PDS) from non-radical to radical-nonradical coexist during PDS activation process, exhibiting highest normalized Kper-site value, which was up to 1.474 × 104 min-1mol-1. Both experimental and theoretical results demonstrate that the electron-rich oxygen (O) can result in more unoccupied orbitals and up-shift the d-band center, and thereby optimizes the PDS adsorption energy by producing multiple reactive oxygen species for BPA removal. This work provided a potential approach for the coordination environment modulation of SSCs to regulate persulphate activation pathway in environmental remediation.

Enhanced degradation of Rhodamine B through activating peroxydisulfate by humic acid-Fe incorporated biochar: Kinetics and mechanism studies

Sulfate radical advanced technologies (SR-AOPs) has been increasingly applied for chemical oxidation of toxic wastewater treatment, while the sluggish kinetics of Fe(III)/Fe(II) cycling remains a serious problem in its application. In this study, a novel co-catalyst of humic acid-Fe incorporated biochar (HA-Fe@BC) was successfully synthesized that can greatly accelerate the Fe(II) regeneration. More than 95 % organic pollutants could be degraded in HA-Fe@BC/peroxydisulfate (PDS) system, especially for the model pollutant Rhodamine B (an almost 8.0-fold kinetic increase). More excitingly, the superior catalytic activity of HA-Fe@BC for PDS activation may be attributed to the ample surface C-OH and C=O groups, accelerated electron transfer and formed surface HA-Fe@BC-PDS* complex with efficient oxidation activity. Radical capture, quenching experiments and electrochemical analysis confirmed that the HA-Fe@BC/PDS was caused by radicals (SO4•-+ O2•-+•OH = 68.13 %) and non-radical (surface-mediated electron transfer and 1O2 = 26.33 %) pathways. Besides, it also exhibited anti-interference performance against anions and organic matter (eg. Cl-, Br-, NO3–, and PO43-). Furthermore, the degradation pathways were proposed by LC-MS assisted with density functional theory (DFT) calculations, and the mechanism was proposed comprehensively. This work demonstrates the PDS activation by HA-Fe@BC through free radical and non-free radical pathways, which provides insight into application of biochar-based materials for wastewater treatment.

The visible optical driving N-S co-doped La2Ti2O7 activated peroxydisulfate for carbamazepine removal: Mechanism and performance

Carbamazepine (CBZ) as an “emerging pollutant”, which poses a threat to human health. Photocatalytic activation of peroxydisulfate (PDS)-based advanced oxidation processes (AOPs) can deep oxidation of CBZ pollutants through the generation of free radicals with high redox potential. However, most of common photocatalysts only have a narrow band gap, which limits their application under visible light. In order to broaden the band gap of photocatalysis, herein we report the N-S co-doping in La2Ti2O7 (N-S LTO) is viable, and then evaluate the visible light activation of PDS to remove the pollutants of CBZ. Compared with pure LTO and N or S mono-doped LTO, the degradation efficiency of CBZ in N-S LTO/PDS/Vis system was 2.18, 1.45, and 1.41 times improved, respectively, under the visible light irradiation condition. Furthermore, the mechanism of CBZ degradation under N-S LTO/PDS/Vis processes was explored and revealed that the HO• and SO4•− were the main substances for the breakage of CBZ molecules. The further physicochemical characterization of samples convinced the active sites in N-S LTO for PDS motivation and oxidation processes with the best separation and migration ability of carriers than other samples. Finally, combined with density functional theory (DFT) calculations, the detailed degradation pathways of CBZ were proposed. This work not only provides insight into the construction of photocatalysts with co-doping for PDS activation, but also brings an inspiration of CBZ degradation in water treatment.

In-situ construction of nitrogen-doped porous carbon nanosheets supported well-dispersed Fe3O4 nanoparticles for efficient purification of antibiotic wastewater via peroxydisulfate activation

Heterogeneous catalysts composed of transition metal oxides and carbon-based materials have displayed significant potential in persulfates activation for the elimination of diverse refractory organic pollutants. Herein, the nitrogen-doped porous carbon (N-pC) nanosheets supported well-dispersed Fe3O4 nanoparticles (Fe3O4/N-pC) were meticulously designed and fabricated. This fabrication process involved the creation of Fe3+/(CN@PDA) precursor through loading polydopamine-Fe3+ complex on graphitic carbon nitride (g-C3N4) and the following calcination process, resulting in in-situ formation of Fe3O4 nanoparticles on the N-pC nanosheets that were derived from polydopamine coated g-C3N4. The large specific surface area, coupled with accessible Fe2+/Fe3+ species, facilitated the synergy of adsorption and catalysis, enabling the rapid elimination of antibiotics via peroxydisulfate (PDS) activation. The optimal Fe3O4/N-pC catalyst demonstrated a remarkable efficacy in the degradation of tetracycline-hydrochloride (TC), reaching a quasi-first-order kinetic constant of 0.1479 min−1, which was 1.95 times that of the degradation reaction using g-C3N4 (0.0758 min−1). Mechanistic investigations revealed that both radicals (·O2-,·OH and SO4·-) and non-radical (1O2 and electron transfer) oxidation pathways were involved in TC degradation. The toxicities of degradation intermediates were assessed through a bean-sprout planting experiment and the quantitative structure-activity relationship (QSAR) analysis. This work offers some guidance on the preparation and application of heterogeneous catalysts for effectively removing organic contaminants from water.