Fukui Index Research Articles

The design and preparation of PDI modified NH2-MIL-101(Fe) for high efficiency removal of dimethoate in peroxymonosulfate system: Performance, mechanism, pathway and toxicity assessment

The widespread use of organophosphorus pesticide dimethoate (DMT) in agriculture poses a threat to human health. In this work, the perylene tetracarboxylic diimide (PDI) modified NH2-MIL-101(Fe) (PDI/MIL) with strong covalent bond C(=O)–N were designed and prepared by a step solvothermal method. The synergistic effect between photocatalytic and peroxymonosulfate (PMS) activation for the DMT elimination over PDI/MIL was gained. Interestingly, PDI/MIL(1:10)/PMS showed boosting degradation efficiency (95.6%) for DMT under 18 min simulated sunlight irradiation. Its apparent reaction rate constant was 24.7 times higher than that of NH2-MIL-101(Fe)/PMS. Moreover, its reusability, stability and mineralization ability were evaluated, and a remarkable mineralization rate of 95.3% with 90 min was achieved. The enhanced activity were attributed to the formation of amide bond that exhibited superior charger transport ability and amount of produced active species. Combined the results obtained from the HPLC-MS and molecular structure characteristics of DMT analyzed by Fukui index, the degradation pathways were proposed. The toxicity of intermediates were predicted by Ecological Structure Activity Relationship (ECOSAR), Toxicity Estimation Software Tool (T.E.S.T.), and Vibrio fischeri experiments. Our work provided deep insights into the mechanisms of DMT degradation via photocatalysis-activated PMS over organic semiconductor modified metal organic frameworks.

Efficient Preparation of S-Scheme Ag/AgBr/BiOBr Heterojunction Photocatalysts and Implications for Degradation of Carbendazim: Mechanism, Pathway, and Toxicology.

Carbendazim (CBZ), as a highly effective benzimidazole fungicide, has a good control effect on various crops caused by fungi. However, excessive use of CBZ in water, atmosphere, soil, and crops has serious effects. The efficient degradation of CBZ is an effective way to reduce its toxic effect. In this work, the type of S-scheme Ag/AgBr/BiOBr heterojunction photocatalyst was effectively prepared by a simple one-step solvothermal in situ method and first applied to the mineralization and degradation of CBZ. The effects of the molar ratio of AgBr to BiOBr, catalyst dosage, CBZ concentration, pH value of the original solution, and inorganic salt ions on the photocatalytic degradation performance of CBZ were comprehensively studied. The results showed that, under visible light irradiation, 0.9-Ag/AgBr/BiOBr (0.9-AAB) exhibited the best photocatalytic degradation performance (88.9%) against the concentration at 10 mg/L of CBZ in original solutions with pH of 10. However, the degradation effect was also good at pH 7. After 90 min, the degradation efficiency reached 86.0%, corresponding to a TOC removal efficiency of 84.0%. The results indicate that the main active species are 1O2 and •O2- free radicals according to the free radical quenching experiments and electron spin resonance spectra. Combined with the XPS characterization results, the electron transfer mechanism of the S-scheme heterojunction was deeply revealed. Additionally, the degradation pathway of CBZ was proposed through both the intermediate identification and the theoretical calculation derived from the DFT Fukui index. Finally, the toxicity of CBZ and the degradation intermediates were predicted based on the T.E.S.T.

Mechanism for Site-Selective Hydroboration of C70 Fullerene with Borane by DFT-D3 Study.

We studied the hydroboration of the C70 fullerene using both B3LYP-D3(BJ)/6-311G(d,p) and M06-2X-D3/6-311G(d,p) levels of theory, incorporating the empirical dispersion interaction, and Fukui index calculations. Potential energy surfaces (PESs) and Gibbs free energy surfaces (GFESs) were calculated for the pathways from four BH3 adducts (located at the AB, CC, D, and E sites) on the C70 to eight products formed by the 1,2-addition of BH3 across the four [6,6]-ring fused bonds (AB, CC, DE, and EE) and across the two [5,6]-ring fused bonds (AA and DD). These pathways are two-step consecutive reactions. We denoted the positions on the fullerene cage as A through E, from the pole to the equator, based on the D5h symmetry of the C70 fullerene. In the first step reaction, the product ratios for the four adduct intermediates should be as the primary intermediate BH3(D), the secondary intermediate BH3(AB), the tertiary intermediate BH3(CC), and the minor intermediate BH3(E), based on the Fukui indices. In addition, in the second step reaction, transition states (TSs) from four adduct intermediates to eight product isomers, namely, BH2(A)H (B) to BH2(E)H (E), were obtained using the QST2 method. The calculated reaction coordinates showed exothermic reactions for all bonds except the EE bond. We also confirmed the transition states by frequency calculations and intrinsic reaction coordinate (IRC) analyses. The PESs and GFESs suggest spontaneous processes for the four isomers, of which the primary products are BH2(A)H (B) and its isomer BH2(B)H (A), the secondary product is BH2(C)H (C), and the tertiary product is BH2(D)H (D), all formed through adduct intermediates. Therefore, through the hydroboration reaction of C70, we could predict and design the site selectivity of C70 by controlling the energy barrier of the transition state in the second step of the reaction. This implies that we could selectively synthesize mainly BH2(B)H (A) isomers across the AB-[6,6]-ring fused bond and also design BH2(D)H(D) isomers across the DD-[5,6]-ring fused bond. Also, the calculations of formation rate constants can well simulate the experimental ratio of two C70H2 isomers by the hydrolysis of BH2(A)H(B), BH2(B)H(A), and BH2(C)H(C) products at room temperature.

Boosting charge separation and active sites exposure by hollow S-scheme MoSe2/Fe2O3 heterojunction for enhanced photocatalytic peroxymonosulfate activation towards ciprofloxacin removal

Regulating the properties of heterogeneous catalyst for efficient peroxymonosulfate (PMS) activation to pollutants degradation remains a challenge in photo-assisted Fenton-like reaction (PF) system. In this study, the novel S-scheme MoSe2/Fe2O3 (H-FMS) heterojunction with hollow nanostructure was successfully developed as visible-light-driven PMS activator for removal of ciprofloxacin (CIP). The prepared H-FMS catalyst in PMS/H-FMS/light system exhibits outstanding photocatalytic performance for CIP degradation, achieving 95.92 % removal of 5 mg/L CIP in 30 min with 0.5 mM PMS. The construction of S-scheme heterojunction provides photoinduced carriers with longer lifetime and higher redox abilities, thus sufficient photogenerated carriers are supplied to directly activate PMS. Simultaneously, the hollow nanostructure possessing multiple light reflection and scattering behaviors further facilitates the utilization of visible light. More importantly, high concentration of photoinduced electrons with high reduction ability in MoSe2 is conducive to continuous exposure of Mo4+ active sites for PMS activation through cycling between transition metal valence states. Overall, effectively separated electron-hole pairs and continuously exposed transition metal active sites both contribute to efficient activation of PMS as well as multi-path generation of ROS, leading to significant improvement in CIP degradation. The results of quenching experiment, electron spin resonance (ESR) technology, liquid chromatography-mass spectrometry (LC-MS) and density functional theory (DFT) calculation confirm that both free radicals (SO4∙-, •OH and O2∙-) and non radicals (1O2 and h+) attack the active sites of CIP possessing high Fukui index, thus contributing to CIP degradation. This work would provide a novel insight for future development and application of photocatalytic PMS activation catalysts in water remediation.

Synergism of Computational Simulation Technique and Machine Learning Algorithm for Prediction of Anticorrosion Properties of Some Antipyrine Derivatives.

This study aimed to predict the selected antipyrine compounds' inhibitory efficiencies and anticorrosion properties in a hydrochloric acid (HCl) environment. Molecular descriptors and input variables were obtained using density functional theory (DFT), and the variance inflation factor (VIF) was employed to reduce redundant variables, leading to the selection of seven quantum chemical descriptors as input variables. Using machine learning techniques such as K-nearest neighbor (KNN) and artificial neural network (ANN), a predictive model was built for 39 antipyrine compounds with known corrosion inhibition efficiencies for carbon and low alloy steel in hydrochloric acid solutions. The models' predictive capability was assessed using cross-validation, with the ANN model showing superior performance, achieving a coefficient of determination (R2) value of 0.715 compared to 0.548 for the KNN model. Performance metrics such as the mean square error (MSE), mean absolute error (MAE), and root-mean-square error (RMSE) further confirmed the superiority of the ANN model over the KNN model. The corrosion inhibition efficiencies (CIEs) of the selected antipyrine compounds ranged from 68.78 to 99.79%, with compound A1 demonstrating the highest CIE of 99.79% and compound A3 the lowest, as evaluated by the ANN model. Analysis of Fukui index parameters obtained from the Mulliken population analysis suggested that the nucleophilic and electrophilic sites play a crucial role in the interactions between the inhibitor and the metal atom through electron donor-acceptor interactions. Moreover, the energy of adsorption (Eads) in kcal·mol-1 decreased in the order of A1 (-187.8) > A2 (-132.0) > A2 (-84.4), with the high negative value of Eads indicating strong and spontaneous adsorption. Further analysis using radial distribution functions and molecular dynamics simulations revealed that inhibitor A1 exhibited predominantly chemisorption, inhibitor A2 showed a mixed type, and inhibitor A3 demonstrated predominantly physisorption, aligning well with the results of the predictive studies.

Interface and Defect Engineering in 3D Co3O4‐Ov/TiO2 to Boost Simultaneous Removal of BPA and Cr(VI) upon Photoelectrocatalytic/Peroxymonosulfate (PEC/PMS) System

AbstractThe combination of photoelectrocatalytic (PEC) and peroxymonosulfate (PMS) is an innovative strategy for environmental treatment. And fabricating a highly efficient photoelectrode is the most pivotal factor in PEC reactions. This study designs an advanced Co3O4‐Ov/TiO2 photoelectrode by a dual‐modification strategy encompassing interface engineering and defect engineering. The photoelectric characterization validates the synergy of oxygen vacancies and dual heterojunctions. Simulated electron density distribution and Kelvin probe force microscopy (KPFM) elucidate the charge transfer pathway between Co3O4‐Ov and TiO2. 1O2 and SO4 .− are confirmed to be primarily responsible for the BPA oxidation in PEC/PMS system by radical scavenger experiments and the EPR technique. And the attack sites of BPA are precisely identified based on the Fukui index. Furthermore, density functional theory (DFT) calculations testify that Co3O4‐Ov can improve the adsorption capacity of PMS and reduce the energy barrier of the reaction process, while XPS analysis showed Co3+/Co2+ redox couple can accelerate PMS activation. Enhanced anode oxidation can effectively promote cathode reduction and consequently Co3O4‐Ov/TiO2‐PMS/PEC system presents a superior removal of both pollutants within only 15 min with fast kinetics (0.15 min−1 for BPA, 0.29 min−1 for Cr(VI)). This work provides unique insight into designing a highly efficient PMS/PEC system for simultaneous pollutant treatment.

Persistent luminescent ZnAl-LDH nanosheets for all-weather degradation of nitenpyram and tetracycline: Superoxide radical induction, life cycle analysis and engineering applications

Photocatalysts designed for all-weather applications, capable of efficient charge carrier separation, are set to transform the adoption of photocatalysis-driven advanced oxidation processes in wastewater management. In this investigation, an energy-storing ZnAl-LDH@SrAl2O4:Eu2+, Dy3+ (SALDH) was synthesized successfully, optimized for the photocatalytic selective degradation of NTP and tetracycline hydrochloride (TC) under varying weather conditions, with 100 % degradation of both NTP and TC within 75 min. Remarkably, SALDH demonstrates energy storage capabilities that markedly reduce energy demands relative to traditional photocatalytic approaches. The primary reactive species identified were O2−, and the Fukui index, computed via density-functional theory (DFT), identified the specific interaction sites of O2− on NTP molecules. Utilizing the energy retention properties of SALDH, a novel, environmentally friendly device was engineered for processing organic pollutants in agricultural wastewater. This system harness the energy from solar radiation to induce the oxidation of pollutants. The experiments that were performed in the both artificially prepared lab-scale and actual agricultural WWT plants indicated the degradation efficiencies of 36 % and 37 %, respectively. As seen during the day, both SALDH and persulfate were capable of effectively decomposing organic contaminants; at night, the SA’s luminescence maintained the oxidative ability of ZnAl-LDH. Meanwhile, SALDH combines the corrosion resistance of ZnAl-LDH with good metal compatibility, enabling SALDH to effectively improve the photostability of long afterglow. This work contributes to the existing knowledge on the degradation of organic pollutants by efficient photocatalysts and points to possible implementations in water treatment processes.

Critical trigger of self-assembled bimetallic Fe/Mn-MOF with SnS2 heterojunctions by persulfate activation for efficient tetracyclines photodegradation

Developing advanced strategies, including exposing active site centers, regulating coordination environments, controlling crystallographic facets, optimizing electronic structures and constructing defects for enhancing photocatalytic performance is of great significance to improving the ecosystem. In this study, a novel self-assembled bimetallic Fe/Mn-MOF with SnS2 Z-scheme heterojunction photocatalyst was designed using a facile multistep solvothermal method. Benefiting from the interfacial heterojunction synergistic effect, the photocatalysts exhibited an outstanding catalytic performance. Nearly 91.4% efficiency of tetracyclines was degraded within 80 min through the assistance of a persulfate-based advanced oxidation process. DFT calculations utilizing the Fukui index identified the sites vulnerable to attack by the active species. As demonstrated by the trapping experiments and electron spin resonance (ESR), the involved oxygen-active species (•O2− and 1O2) facilitated the rapid degradation of tetracycline. The degradation pathways were further guided in the elucidation of the rationale mechanism and the toxicity of derived intermediates was revealed. This work opens a new strategy for the rational design of bimetallic photocatalysts, emphasizing interface-modulated heterojunctions for efficient solar energy conversion.

Insight into the nonradical selective oxidation mechanism for versatile organic pollutants removal by perovskite activated peroxymonosulfate system

The heterogeneous catalysis of peroxymonosulfate (PMS) through nonradical pathway has shown many advantages in environmental remediation. It is necessary to unveil the factors affecting oxidation routes and selectivity toward different organic pollutants. Herein, a series of ABO3-type BiFexCo1-xO3 perovskite catalysts were fabricated via simple hydrothermal process to realize the changeover of catalytic activity and mechanism in PMS activation and pollutants oxidation. The as-prepared BiFe0.5Co0.5O3 (BFCO-3) achieved a 98 % removal efficiency of SMZ with a high kinetic constant (kobs = 0.334 min−1) in 10 min. The superior catalytic performance was ascribed to the introduction of bimetals at B-site, which enhanced electron donating capacity to PMS, confirming by d-band center calculations. Several parameters such as inorganic anions and humic acids affected the SMZ degradation slightly, owing that singlet oxygen was verified to be the primary reactive species in the BFCO-3/PMS system. Moreover, twelve organic pollutants including amoxicillin crystalline (AMX), cephalexin hydrate (CFX), ciprofloxacin (CIP), levofloxacin (LFX), Sulfadiazine (SDZ), sulfamethoxazole (SMZ), 4-acetamidophenol (ACP), benzoic acid (BA), bisphenol A (BPA), carbamazepine (CBZ), metronidazole (MNZ) and naproxen (NPX) were utilized to investigate the selective oxidation mechanism. A linear correlation between lnkobs and their half-wave potential (φ1/2) values (except for BA and MNZ) suggesting the dominant role of nonradical catalysis where phenolic compounds with lower anodic potential tend to lose electrons are more easily degraded. Furthermore, the reactive sites of representative SMZ for electrophilic species attack were precisely identified based on the Fukui index. And the degradation intermediates of SMZ were further determined by LC-MS/MS technology for proposing their degradation pathway and predicting ecotoxicity. This study not only provides an efficient advanced oxidation system for organic pollutants removal but also advances our understanding of the selective oxidation mechanism in nonradical-dominated catalytic process.

Construction of C3N4/Ag2S p-n semiconductor heterojunction coupled with Ag-induced SPR effect on CF cloth for improving photocatalytic activity

C3N4/Ag2S p-n semiconductor heterojunction coupled with Ag-induced SPR effect on carbon fiber cloth with large macroscopic area, recyclability and excellent photocatalytic performance was prepared by thermal condensation-chemical precipitation. CF/C3N4/Ag/Ag2S cloth showed strong Vis-NIR light absorption and outstanding separation efficiency of photo-generated electron and hole pairs. CF/C3N4/Ag/Ag2S cloth displayed a markedly enhanced catalytic activity (94 % of TC, 85 % of Cr(VI)) compared with CF/C3N4 cloth (52 % of TC, 50 % of Cr(VI)) or CF/Ag/Ag2S cloth (34 % of TC, 19 % of Cr(VI)), attributing to the establishment of p-n junction along with Ag SPR effect. Moreover, degradation pathways for TC were proposed utilizing HPLC-MS and Fukui index analysis, and photocatalytic mechanism was confirmed by active species experiments and DFT computations. This facile strategy provides novel approach to the synthesis of material with large macroscopic areas, recyclability, and excellent photocatalytic property for degrading contaminants from wastewater.

Floatable expanded perlite-loaded Z-scheme n-C3N5/Ag2CO3 core-shell structure with C-defects for enhanced adsorption and photodegradation of microcystin-LR: Insights into performance and mechanism

Efficient in-situ treatment of high concentrations microcystin-LR in surface waters is especially challenging. Herein, spherical floatable Z-scheme core-shell photocatalyst EP@n-C3N5/Ag2CO3 (EP@CNAC) with carbon defects was constructed using expanded perlite (EP) as floating carrier for efficient adsorption and degradation of microcystin-LR. The carbon defect sites and electron density distribution of C3N5 were investigated by DFT calculation. Benefited from synergistic effects of morphology and defect engineering, Z-scheme heterojunction, and floatability, the carrier migration kinetics and solar spectral responsiveness of EP@CNAC-3 were significantly enhanced, and 97 % of microcystin-LR was degraded within 16 min. The LC-MS, Fukui index, and electrostatic potential of microcystin-LR revealed that Adda side chain was cleaved by electrophilic attack of 1O2, while ring-opening reaction and decarboxylation were caused by nucleophilic attack of •O2- and strong oxidative properties of h+, respectively. These findings are expected to bring new insights into design of innovative floating photocatalysts and in-situ remediation mechanism of microcystin-LR.

Peroxymonosulfate activation by CoO@C catalyst from integrated recycling of spent lithium-ion battery: Performance and mechanism

Developing low-cost, highly active transition metal-based catalysts for peroxymonosulfate (PMS) activation is essential but remains challenging. Herein, we proposed a novel “waste-to-energy” strategy to derive an effective PMS activator (CoO@C) by integrally utilizing the abundant Co content in the cathodes and the defective structure of anode graphite from spent lithium-ion batteries (LIBs). The CoO@C/PMS system could completely degrade atrazine (ATZ) within 15 min, along with a robust resilience to coexisting substrate and a wide pH range of 5.0–11.0. Through quenching experiments and electron paramagnetic resonance (EPR), •OH was identified as the primary reactive oxygen species (ROS) responsible for ATZ degradation. Furthermore, electron transfer between the catalyst and PMS was examined via density functional theory (DFT) calculations to elucidate the activation mechanism. The Fukui index pinpointed the vulnerable sites of ATZ, offering insights into the possible degradation pathways along with UHPLC-MS analysis. Furthermore, CoO@C was fixed on a polyethersulfone (PES) membrane for continuous degradation of ATZ, which maintained a degradation efficiency exceeding 90 % after treating 6 L of wastewater. This research provided valuable insights into the preparation of metal-based catalysts for advanced oxidation processes and achieved the sustainable utilization of spent LIBs.

Zinc indium sulfide coupling with graphitic carbon nitride containing non-intrinsic oxygen vacancies to form Z-scheme heterojunction for boosting photodegradation of tetracycline

A novel graphitic carbon nitride containing non-intrinsic oxygen vacancies (Vo-CN) is interfacial coupling with zinc indium sulfide (ZIS) to form Z-scheme heterojunction (VCZ) for efficient tetracycline (TC) degradation. The TC removal rate by VCZ-1 (mass ratio of Vo-CN: ZIS is 1:20, 0.2 g/L) achieves 99.86 %. VCZ-1 reveals outstanding reusability and stability with an unchanged TC degradation rate after undergoing five cycles. VCZ-1 achieves high-efficiency TC degradation in various water matrices. The experimental and DFT calculations indicate that the built-in electric field drives charges on Vo-CN transfer to ZIS, forming a Z-scheme VCZ-1 heterojunction. The strong electronic coupling effect between Vo-CN and ZIS facilitates charge exchange at the heterojunction interface. Non-intrinsic oxygen vacancies in VCZ, as binding sites for electrons and holes, effectively lower the energy barrier for singlet excitons converting to triplet excitons. The triplet excitons are induced to transfer energies to dissolved oxygen and expedite 1O2 production. 1O2 synergizes with •O2– and •OH to attack O-containing groups and hexatomic rings in TC, inducing demethylation, hydroxylation, dihydroxylation, and ring-opening reactions. Three possible degradation pathways are inferred by UPLC/MS/MS and Fukui index of TC. The ecotoxicity evaluation of intermediate products highlights the benefits of VCZ-1 photocatalytic oxidation in ensuring environmental safety. This work proposes a novel idea for constructing efficient Z-scheme photocatalysts for environmental remediation.

Construction of CoFe2O4/Fe2O3 S-type heterojunctions on biochar for activating peroxymonosulfate towards simultaneous removal of TC and Cr(VI)

The construction of S-type heterojunctions for restraining the rapid recombination of photogenerated charges is considered an efficient approach to boost redox capacity. Herein, the growth of CoFe2O4/Fe2O3 S-type heterojunctions on biochar (BC) was accomplished by thermal polymerization-hydrothermal. BC/CoFe2O4/Fe2O3 displayed a wide range of light absorption from 200 to 800 nm and enhanced photocurrent (0.41 μA cm−2). Furthermore, BC/CoFe2O4/Fe2O3 can remove tetracycline (TC) (98.84 %) and Cr(VI) (88.43 %) more efficiently compared to the CoFe2O4 (40.32 % of TC, 68.52 % of Cr(VI)) and Fe2O3 (29.81 % of TC, 53.67 % of Cr(VI)) single counterparts upon 45 min visible light irradiation in the presence of peroxymonosulfate (PMS). Free radical capture experiments revealed that •OH, •O2−, and SO4−• are the primary activated species for the removal of TC and e− is the major activated species for the removal of Cr(VI). Meanwhile, the degradation pathway of TC was monitored via LC-MS and Fukui index calculations. Combining density functional calculations (DFT) with UPS and radical capture tests, the possible mechanism of photocatalytic degradation was proposed. The findings demonstrated the remarkable photocatalytic activity and stability of the photocatalyst, evidencing the potential of BC/CoFe2O4/Fe2O3 for practical wastewater treatment.

Regulation of reactive oxygen species generation by graphitization and defect degree of Co-loaded carbon in peroxymonosulfate activation

The designing of functional groups and structured active sites is a vital strategy for efficient Peroxymonosulfate (PMS)-based advanced oxidation processes (PMS-AOPs). However, the regulation mechanism and correlation of graphitization/defect degree and reactive oxygen species (ROS) are still not fully understood for a composite catalyst. Herein, a family of metal–organic framework (MOF)-derived cobalt-nitrogen-carbon with different graphitization/defect degrees was designed and synthesized successfully to activate PMS for carbamazepine (CBZ) degradation. NC-0.6/PMS system exhibited efficient performance for several contaminants, but NC-10/PMS system preferred to remove contaminants with low electrophilicity. The correlation analysis and Fukui index calculation revealed that high graphitization and low defect degree of catalysts stimulated diverse ROS generation (•OH and 1O2) and the decreasing of graphitization was beneficial to form a single 1O2 oxidation system. The regulation of ROS was a potential approach for the selective removal of contaminants. This work provides a new insight into the mechanism transformation of ROS-oriented degradation of pollutants in PMS-AOPs.

Insight into the photothermal boosted ofloxacin removal by magnetic CuFe2O4/pyrite waste catalyst: Mechanism, degradation pathways, and toxicity evaluation

The widespread distribution of antibiotics in natural waters has raised global concerns due to their potential threat to the aquatic environment. In this study, 40 %-CuFe2O4/pyrite waste composite material was constructed for the removal of ofloxacin (OFX) through activating H2O2 in photothermal Fenton processes. It had excellent photothermal conversion performance and could serve as a superior photothermal-Fenton catalyst. The removal efficiency of OFX was 96.13 % in the photothermal Fenton reaction, and the apparent first-order kinetics rate constant (k) was 4.33 and 12.15 times higher than in the traditional Fenton without light and 40 %-Fe/PW photothermal Fenton reaction. This could be attributed to the introduction of photothermal effect promoted collisions between substances, and expedited the reaction rate. The redox cycle of Fe(II)/Fe(III) and Cu(I)/Cu(II) in the Cu-Fe bimetal system also contributed to the removal of OFX. Besides, it exhibited excellent cycling stability, extensive adaptability for various pollutants and water properties. The order of contribution of active radicals to the removal of OFX was ∙ OH>h+ >∙O2-, and they attacked the active atoms of OFX molecule with high Fukui index. Hopefully, this study may encourage the utilization of the photothermal effect for contaminant removal and introduce a novel perspective for environmental remediation.

Discerning the role of a site cation in ACoO3 perovskites for boosting Co3+/Co2+ redox cycle for pollutant degradation: DFT calculation, mechanism and toxicity evolution

The degradation of persistent and refractory pollutants, particularly plastic and resins manufacturing wastewater, poses a significant challenge due to their high toxicity and high concentrations. This study developed a novel hybrid ACoO3 (A = La, Ce, Sr)/PMS perovskite system for the treatment of multicomponent (MCs; ACN, ACM and ACY) from synthetic resin manufacturing wastewater. Synthesized perovskites were characterized by various techniques i.e., BET, XRD, FESEM with EDAX, FTIR, TEM, XPS, EIS, and Tafel analysis. Perovskite LaCoO3 exhibited the highest degradation of MCs i.e., ACN (98.7%), ACM (86.3%), and ACY (56.4%), with consumption of PMS (95.2%) under the optimal operating conditions (LaCoO3 dose 0.8 g/L, PMS dose 2 g/L, pH 7.2 and reaction temperature 55 °C). The quantitative contribution (%) of reactive oxygen species (ROS) reveals that SO4•− are the dominating radical species, which contribute to ACN (58.3% for SO4•− radicals) and ACM degradation (46.4% for SO4•− radicals). The tafel plots and EIS spectra demonstrated that perovskites LaCoO3 have better charge transfer rates and more reactive sites that are favorable for PMS activation. Further, four major degradation pathways were proposed based on Fukui index calculations, as well as GC-MS characterization of intermediate byproducts. Based on a stability and reusability study, it was concluded that LaCoO3 perovskites are highly stable, and minimal cobalt leaching occurs (0.96 mg/L) after four cycles. The eco-toxicity assessment performed using QSAR model indicated that the byproducts of the LaCoO3/PMS system are non-toxic nature to common organism (i.e., fish, daphnids and green algae). In addition, the cost of the hybrid LaCoO3/PMS system in a single cycle was estimated to be $34.79 per cubic meter of resin wastewater.

Solar-light-driven photocatalytic degradation and detoxification of ciprofloxacin using sodium niobate nanocubes decorated g-C3N4 with built-in electric field

Simultaneous degradation and detoxification during pharmaceutical and personal care product removal are important for water treatment. In this study, sodium niobate nanocubes decorated with graphitic carbon nitride (NbNC/g-C3N4) were fabricated to achieve the efficient photocatalytic degradation and detoxification of ciprofloxacin (CIP) under simulated solar light. NaNbO3 nanocubes were in-situ transformed from Na2Nb2O6•H2O via thermal dehydration at the interface of g-C3N4. The optimized NbNC/g-C3N4-1 was a type-I heterojunction, which showed a high conduction band (CB) level of −1.68 eV, leading to the efficient transfer of photogenerated electrons to O2 to produce primary reactive species, •O2−. Density functional theory (DFT) calculations of the density of states indicated that C 2p and Nb 3d contributed to the CB, and 0.37 e– transferred from NaNbO3 to g-C3N4 in NbNC/g-C3N4 based on the Mulliken population analysis of the built-in electric field intensity. NbNC/g-C3N4-1 had 3.3- and 2.3-fold of CIP degradation rate constants (k1 = 0.173 min−1) compared with those of pristine g-C3N4 and NaNbO3, respectively. In addition, N24, N19, and C5 in CIP with a high Fukui index were reactive sites for electrophilic attack by •O2−, resulting in the defluorination and ring-opening of the piperazine moiety of the dominant degradation pathways. Intermediate/product identification, integrated with computational toxicity evaluation, further indicated a substantial detoxification effect during CIP degradation in the photocatalysis system.

Ag nanoparticle-mediated LSPR effect and electron transfer for enhanced oxidative degradation process of g-C3N5 nanoflowers

The design of photocatalytic system with broad-spectrum response to sunlight and rapid electron transfer is critical for efficient destruction of diverse contaminants in various environmental situations. Herein, self-assembled supramolecular strategy was employed to anchor Ag nanoparticles on the nanoflower-like g-C3N5 surface to construct Schottky-type catalyst (ACN-1) for efficient degradation of organic contaminants. The localized surface plasmon resonance (LSPR) effect significantly improves photocatalytic activity of materials by boosting rapid transfer of interlayer energy and photogenerated electrons and extending the absorption edge of catalysts into near-infrared light region. In actual water samples, ACN-1 entirely eliminated tetracycline (k = 1.0787 min−1) within 40 min and maintained high degradation rate (more than 80 %) under various water quality parameters. Furthermore, ACN-1 demonstrated remarkable suitability to microcystin-LR (98.9 %, k = 0.08098 min−1), sulfamethoxazole (81.2 %, k = 0.02984 min−1), and methylene blue (91.4 %, k = 0.04072 min−1). Quenching experiments and ESR tests showed that main active species in system were 1O2, •O2−, and h+. Finally, five photodegradation pathways and 26 intermediates of TC were elucidated by combining ESR signals, LC-MS and Fukui index. After photodegradation treatment, the toxicity of solution was drastically reduced and the mineralization reached 62.48 %. This study provides new insights into the design and interaction mechanisms of novel g-C3N5-based catalysts and effectively contributes to remediation strategies for emerging pollutants in water.

Comet-like Co-MOF with TiO2 nanoparticles decorated used to efficiently activate peroxymonosulfate for larotrectinib degradation through radical and non-radical pathways

Removal of emerging contaminants has drawn great concern due to their potential high risk to eco-environment system and human health. In this study, an emerging and broad-spectrum anticancer pharmaceutical, larotrectinib (LOXO), was focused on to achieve its degradation in water. A heterogenous peroxymonosulfate (PMS) activation system was constructed by using a comet-like Co-based metal–organic framework (Co-MOF) with TiO2 nanoparticles decorated. The optimized material (TiO2/Co-MOF1) showed high PMS activation efficiency, and thus 90.1 % of LOXO could be quickly degraded within 10 min. Scavenger quenching tests and electron paramagnetic resonance (EPR) analysis indicated that both radicals (OH and SO4-) and non-radical species (1O2) contributed to LOXO degradation. The two main components of Co-MOF and TiO2 nanoparticles in the composite showed a synergetic effect on PMS activation: Co-MOF offered coordination cobalt for PMS activation, while TiO2 provided abundant –OH groups for interface complexation to promote the electron transfer. In addition, 1O2 originates from directional conversion of O2– after PMS activation at the material’s surface. Moreover, density functional theory (DFT) calculation suggests that the atoms in LOXO with high Fukui index (f-) representing electrophilic attack are the reactive sites. Toxicity analysis based on quantitative structure–activity relationship (QSAR) verifies the reduced toxicity of degraded intermediates/products. This work proposed an available technology to efficiently activate PMS for anticancer drugs degradation through both radical and non-radical pathways in wastewater.