B,N-decorated carbocatalyst based on Fe-MOF/BN as an efficient peroxymonosulfate activator for bisphenol A degradation

Roles of BOCu sites and graphite nitrogen on persulfate non-radical activation for tetracycline degradation

The activation of peroxymonosulfate (PMS) by carbon-based catalysts is deemed to be a promising method for the degradation of refractory organic contaminants in wastewater. Herein, a Cu-doping strategy in B and N co-doped carbon nanotubes with highly dispersed BOCu sites and graphite nitrogen were successfully synthesized for activating PMS to degradate tetracycline. The best removal rate of tetracycline within 60 min (97.63 %) was obtained by the 1.5 % Cu-BNC and the degradation rate was increased by 17.9 times. The enhanced catalyst activity was attributed to the promoting the cycle of the Cu(I)/Cu(II) redox pair by the formed BOCu sites, and the accelerating the electron transfer process by the adsorption of graphitic N for PMS. The non-free radical pathway including 1O2 and electron transfer played a dominant role in the 1.5 % Cu-BNC/PMS system. The degradation intermediates of TC were identified and three possible degradation pathways were proposed. Further toxicity analysis of the intermediates showed that the 1.5 % Cu-BNC/PMS system had a significant effect on weakening and reducing the biological toxicity and mutagenicity of TC. Moreover, it presented an excellent degradation performance in raw natural water. In general, the proposed regulation of carbon-based catalysts via the coordination-driven effect provides ideas for efficient wastewater treatment.

Crystal Plane Regulation Promotes the Oriented Conversion of Radicals in Heterogeneous Persulfate Catalyzed Oxidation Process

In heterogeneous persulfate-catalyzed oxidation systems, the mechanism underlying the crystal plane effects of the catalyst on the selective conversion of reactive oxygen species (ROS) remains ambiguous. In this study, nano-Co3O4 catalysts with varying crystallinity and exposure levels of (111) crystal planes are prepared via a hydrothermal method. Compared to low crystalline catalysts, high crystallinity catalysts predominantly expose (111) planes containing higher concentrations of Co2+ and oxygen vacancies (Ov), resulting in an increase degradation efficiency of p-nitrobenzaldehyde (4-NBA) from 74.5% to 100%. Radical quenching experiments and EPR characterization reveal that the degradation of 4-NBA occurs through a radical pathway, and quantification of radicals demonstrates that increasing exposure levels of (111) planes effectively promote radical yield (CSO4•- increase from 18.2 to 172.8 µm and C•OH increase from 1 to 58.9 µm). Furthermore, XPS and DFT calculations indicate that high crystallinity catalyst possesses more Ov active sites on (111) planes. The presence of Ov not only facilitates the adsorption of PMS molecules but also enhances electron transfer from Co2+ to PMS, leading to directed formation and efficient transformation of radicals. This study presents a novel strategy for promoting efficient radical formation in persulfate-activated systems.

Zr-based multivariate metal-organic framework for rapid extraction of sulfonamide antibiotics from water and food samples

Based on multiple ligands strategy, a series of multivariate metal organic frameworks (MTV-MOFs) named as PCN-224-DCDPSx were prepared using one-pot solvothermal method to extract and remove sulfonamide antibiotics (SAs). The pore structure and adsorption performance can be further regulated by modulating the doping ratios of medium-tetra(4-carboxylphenyl) porphyrin and 4,4'-dicarboxydiphenyl sulfones. The MTV-MOFs of PCN-224-DCDPS1.0 possesses very large specific surface area (1625 m2/g). Using PCN-224-DCDPS1.0 as sorbent, a dispersive solid-phase extraction method was developed to extract and preconcentrate SAs from water, eggs, and milk prior to high performance liquid chromatography analysis. The limits of detection of method were determined between 0.17 and 0.27 ng/mL with enrichment factors ranging 214-327. The adsorption can be finished within 30 s, and the recovery rate remains above 80 % after 10 repeated uses. The adsorption capacities of sorbent were determined from 300 to 621 mg/g for sulfadiazine, sulphapyridine, sulfamethoxydiazine, sulfachlorpyridazine, sulfabenzamide, and sulfadimethoxine. The adsorption mechanisms were investigated and can be attributed to π-π interactions, hydrogen bonds, and electrostatic interactions. This work represents a method for preparation of MTV-MOFs and uses as sorbent for extraction and enrichment of trace pollutants from complex samples.

Cu/N co-doped biochar activating PMS for selective degrading paracetamol via a non-radical pathway dominated by singlet oxygen and electron transfer

The non-free radical oxidation pathway (PMS-NOPs) of peroxymonosulfate (PMS) holds significant promise for practical wastewater treatment applications, owing to its low oxidation potential, high PMS utilization rate, and robust anti-interference capability in the degradation of pollutants. A novel activator copper nitrogen co-doped porous biochar (Cu-N-BC) with rich defect edges and functional groups was obtained by adding Cu and N to the biochar matrix generated by sodium alginate through pyrolysis in this study. Under the condition of 1 mM PMS, 30 mg/L activator was used to activate PMS and achieve efficient degradation of 10 mg/L paracetamol (PCT) within 15 min, with a high reaction rate constants (kobs) of 0.391 min-1. The activation mechanism of the Cu-N-BC/PMS/PCT system was a non-radical activation pathway with the dominance of singlet oxygen (1O2) and the presence of catalyst-mediated electron transfer. The graphite nitrogen, pyridine nitrogen, and Cu-N coordination introduced by Cu/N co-doping, as well as the carbon skeleton and CO functional group of biochar, were considered active sites that promote the 1O2 generation. The Cu-N-BC/PMS system exhibits strong stability, eco-friendliness, effective mineralization, and interference resistance across diverse pH levels (3-11) and interfering ions, including Cl-, H2PO4-, NO3-, SO42-, and humic acid. Remarkably, it efficiently degrades PCT in tap and lake water, achieving a notable 63.73% TOC mineralization rate, with leached copper ions below 0.02 mg/L. This research introduces a novel method for obtaining metal nitrogen carbon activators and enhances understanding of PMS non-radical activation pathways and active sites.

Advances and challenges in the removal of organic pollutants via sulfate radical-based advanced oxidation processes by Fe-based metal-organic frameworks: A review

Organic contaminants, notorious for their complexity and resistance to degradation, are prevalent in aquatic environments, posing severe threats to ecosystems. Sulfate radical-based advanced oxidation processes (SR-AOPs), known for their stability and high effectiveness, have become a common choice for treating organic wastewater. Metal-organic framework materials (MOFs) have garnered substantial attention due to their facile chemical manipulation, unique structural configurations, and other favorable properties. Therefore, this article critically reviews recent advances in research involving the utilization of Fe-based MOFs (Fe-MOFs) and their derivatives in SR-AOPs. Specifically, it highlights the manipulation of influencing factors within the system to enhance the degradation of organic pollutants. The mechanisms and applications underlying the degradation of organic pollutants in the SR-AOPs system are also elucidated.

Non-radical activation of low additive periodate by carbon-doped boron nitride for acetaminophen degradation: Significance of high-potential metastable intermediates

Metal-free environmental-friendly and cost-effective catalysts for periodate (PI) activation are crucial to popularize their application for micropollutant removal in water. Herein, we report that carbon-doped boron nitride (C-BN) can efficiently activate PI to degrade acetaminophen under very low oxidant doses (40 μM) and over a relatively wide pH range (3-9). As expected, the significant reduction in periodate addition is likely to be due to the higher chemical utilization efficiency achieved by a non-radical oxidation pathway. This involved two main mechanisms, the electron transfer process mediated by the high-potential metastable C-BN-900-PI* complex and singlet oxygen. In this case, the CO groups and defects on the C-BN surface were identified as key active sites for PI activation. Notably, the prepared C-BN-900 had good cycling performance and the degradation efficiency is recovered after simple annealing. The existence of HCO3- and HA significantly inhibited the reaction, whereas Cl-, SO42-, and NO3- had little effect on the degradation of ACE. Overall, this study provides a new alternative method to regulate the non-radical pathway of boron nitride/periodate system.

Nitrogen-doped metal-free granular activated carbons as economical and easily separable catalysts for peroxymonosulfate and hydrogen peroxide activation to degrade bisphenol A

The fabrication of low-cost, highly efficient, environmentally friendly, and easily separable metal-free heterogeneous catalysts for environmental remediation remains a challenge. In this study, granular nitrogen-doped highly developed porous carbons with a particle size of 0.25-0.30 mm were prepared by preoxidation and subsequent NH3 modification of a commercially available coconut-based activated carbon, and used to activate peroxymonosulphate (KHSO5) or hydrogen peroxide (H2O2) to degrade bisphenol A (BPA). The nitrogen-doped carbon (ACON-950) prepared by NH3 modification at 950 °C, with the addition of only 0.15 g/L could remove 100% of 50 mg/L BPA in 150 min, and more than 90% of the removed BPA was due to degradation. The removal rates of total organic carbon of ACON-950/KHSO5 and ACON-950/H2O2 systems reached 60.4% and 66.2% respectively, indicating the excellent catalytic activity of ACON-950. The reaction rate constant was significantly positively correlated with the absolute content of pyridinic N (N-6) and graphitic N (N-Q) and negatively and weakly positively correlated with pyrrolic N (N-5) and defects. Quenching experiments combined with electron paramagnetic resonance demonstrated that singlet oxygen was the dominant reactive oxidative species for BPA degradation. ACON-950 was characterized before and after the degradation reaction using N2 adsorption-desorption analyzer, Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS). The results confirmed the prominent contribution of both the N-6 and N-Q to the catalytic performance of nitrogen-doped carbons. The reusability of ACON-950 and its application in actual water bodies further demonstrated its remarkable potential for the remediation of organic pollutants in wastewater.

Surface reconstructed Fe@C1000 for enhanced Fenton-like catalysis: Sustainable ciprofloxacin degradation and toxicity reduction

The Fe-based catalysts typically undergo severe problems such as deactivation and Fe sludge emission during the peroxymonosulfate (PMS) activation, which commonly leads to poor operation and secondary pollution. Herein, an S-doped Fe-based catalyst with a core-shell structure (Fe@CT, T = 1000°C) was synthesized, which can solve the above issues via the dynamic surface evolution during the reaction process. Specifically, the Fe0 on the surface of Fe@C1000 could be consumed rapidly, leaving numerous pores; the Fe3C from the core would subsequently migrate to the surface of Fe@C1000, replenishing the consumed active Fe species. The X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) analyses demonstrated that the reaction surface reconstructed during the PMS activation, which involved the FeIII in-situ reduction by S species as well as the depletion/replenishment of effective Fe species. The reconstructed Fe@C1000 achieved near-zero Fe sludge emission (from 0.59 to 0.08-0.23 mg L-1) during 5 cycles and enabled the dynamic evolution of dominant reactive oxygen species (ROS) from SO4·- to FeIVO, sustainably improving the oxidation capacity (80.0-92.5% in following four cycles) to ciprofloxacin (CIP) and reducing the toxicity of its intermediates. Additionally, the reconstructed Fe@C1000/PMS system exhibited robust resistance to complex water matrix. This study provides a theoretical guideline for exploring surface reconstruction on catalytic activity and broadens the application of Fe-based catalysts in the contaminants elimination.

Progress in the Elimination of Organic Contaminants in Wastewater by Activation Persulfate over Iron-Based Metal-Organic Frameworks

The release of organic contaminants has grown to be a major environmental concern and a threat to the ecology of water bodies. Persulfate-based Advanced Oxidation Technology (PAOT) is effective at eliminating hazardous pollutants and has an extensive spectrum of applications. Iron-based metal-organic frameworks (Fe-MOFs) and their derivatives have exhibited great advantages in activating persulfate for wastewater treatment. In this article, we provide a comprehensive review of recent research progress on the significant potential of Fe-MOFs for removing antibiotics, organic dyes, phenols, and other contaminants from aqueous environments. Firstly, multiple approaches for preparing Fe-MOFs, including the MIL and ZIF series were introduced. Subsequently, removal performance of pollutants such as antibiotics of sulfonamides and tetracyclines (TC), organic dyes of rhodamine B (RhB) and acid orange 7 (AO7), phenols of phenol and bisphenol A (BPA) by various Fe-MOFs was compared. Finally, different degradation mechanisms, encompassing free radical degradation pathways and non-free radical degradation pathways were elucidated. This review explores the synthesis methods of Fe-MOFs and their application in removing organic pollutants from water bodies, providing insights for further refining the preparation of Fe-MOFs.

Insights to PFOS elimination with peroxydisulfate activation mediated by boron modified Fe/C catalysts: Enhancing mechanism of boron and PFOS degradation pathway

In this study, the boron-doped iron-carbon composite (Fe@B/C-2) was prepared via a simple solvothermal and secondary calcination process by using iron metal-organic frameworks (Fe-MOFs) as precursor. The obtained Fe@B/C-2 possessed abundant active sites and low iron ion leaching, and exhibited excellent performance on peroxydisulfate (PDS) activation for efficient PFOS (10 mg/L) degradation (94 %) in 60 min, with 0.2 g/L of catalyst dosage, 1.0 g/L of PDS dosage and at 5.0 of initial pH. The radical scavenging and electron paramagnetic resonance (EPR) tests demonstrated that SO4·- and ·OH were the primary active species during PFOS elimination. Under the attack of these species, PFOS was first transformed into PFOA, followed by a sequential defluorination process, and lastly mineralized into CO2 and F-. Notably, DFT results revealed that Fe species, -BC3/-BC2O structures on the carbon matrix performed crucial roles in PDS activation. The extraordinary catalytic activity of Fe@B/C-2 was attributable to the synergistic effects of Fe nanoparticles and the B-doped on carbon matrix. The doped B not only could activate the inert carbon skeleton and provided more catalytic centers, but also could accelerate the electron transfer efficiency, leading to a boost in PDS decomposition.

Mechanisms of interaction between metal-organic framework-based material and persulfate in degradation of organic contaminants (OCs): Activation, reactive oxygen generation, conversion, and oxidation

Metal-organic frameworks (MOFs)-based materials have been of great public interest in persulfate (PS)-based catalytic oxidation for wastewater purification, because of their excellent performance and selectiveness in organic contaminants (OCs) removal in complex water environments. The formation, fountainhead and reaction mechanism of reactive oxygen species (ROSs) in PS-based catalytic oxidation are crucial for understanding the principles of PS activation and the degradation mechanism of OCs. In the paper, we presented the quantitative structure-activity relationship (QSAR) of MOFs-based materials for PS activation, including the relationship of structure and removal efficiency, active sites and ROSs as well as OCs. In various MOFs-based materials, there are many factors will affect their performances. We discussed how various surface modification projects affected the characteristics of MOFs-based materials used in PS activation. Moreover, we revealed the process of ROSs generation by active sites and the oxidation of OCs by ROSs from the micro level. At the end of this review, we putted forward an outlook on the development trends and faced challenges of MOFs for PS-based catalytic oxidation. Generally, this review aims to clarify the formation mechanisms of ROSs via the active sites on the MOFs and the reaction mechanism between ROSs and OCs, which is helpful for reader to better understand the QSAR in various MOFs/PS systems.

Efficient rhodamine B dye degradation by red mud-grapefruit peel biochar catalysts activated persulfate in water

The continuous and rapid development of textile industry intensifies rhodamine B dye (RhB) wastewater pollution. Meanwhile, massive red mud (RM) solid waste generated by the industrial alumina production process poses detrimental effects to the environment after leaching. For resource utilization and to reduce the expansion of RhB pollution, RM and peel red mud-biochar composite (RMBC) catalyst were synthesized in activating peroxydisulfate (PDS) for RhB degradation. Firstly, characterization results showed that compared to RM, RMBC had a higher content of catalytically active metals (Fe, Al, Ti) (higher than 0.92-4.18%), smaller pore size, and larger specific surface area (10 times), which verified RMBC had more potential catalytic oxidation activity. Secondly, under optimal dosage (catalyst, PDS), pH 4.6, and 20 mg L-1 RhB, it was found that the RhB degradation ratio of RM was 76.70%, which was reduced to 41% after three cycles, while that of RMBC was 89.98% and 67%, respectively. The results indicated that the performance of RMBC was significantly superior to that of RM. Furthermore, the quenching experiments, electron paramagnetic resonance spectroscopy tests, FTIR, and XPS analysis showed the function of O-H, C=O, C-O, Fe-O, and Fe-OH functional groups, which converted the PDS to the active state and hydrolyzed it to produce free radicals ([Formula: see text], 1O2, [Formula: see text]) for RhB degradation. And, Q Exactive Plus MS test obtained that RhB was degraded to CO2, H2O, and intermediate products. This study aimed to raise a new insight to the resource utilization of RM and the control of dye pollution.

Sulfur-decorated Fe/C composite synthesized from MIL-88A(Fe) for peroxymonosulfate activation towards tetracycline degradation: Multiple active sites and non-radical pathway dominated mechanism

Peroxymonosulfate (PMS)-mediated advanced oxidation processes gain growing attention in degrading antibiotics (e.g., tetracycline (TC)) in wastewater for their high capacity and relatively low cost, while designing efficient catalysts for PMS activation remains a challenge. In this study, a sulfur-doped Fe/C catalyst (Fe@C-S) synthesized from iron metal-organic frameworks (Fe-MOFs) was developed for PMS activation towards TC removal. Under optimal conditions, the TC removal efficiency of Fe@C-S150/PMS system within 40 min was 91.2%. Meanwhile, the k value for Fe@C-S150/PMS system (0.2038 min-1) was 3.36-fold as high as the S-free Fe@C-based PMS system. Also, Fe@C-S150/PMS system showed high robustness in different water matrices. Further studies found that the TC degradation mechanism was mainly ascribed to the non-radical pathway (1O2 and electron transfer). Fe nanoparticles, S and CO groups on the catalyst all participated in the generation of reactive oxygen species (ROS). Besides, S species could enhance the Fe2+/Fe3+ redox cycle and accelerate the electron transfer process. This work highlights the critical role of S in enhancing the catalytic performance of Fe/C-based catalysts for PMS activation, which would provide meaningful insights into the design of high-performance PMS activators for the sustainable remediation of emerging contaminants-polluted water bodies.

pH adjustable MgAl@LDH-coated MOFs-derived Co2.25Mn0.75O4 for SMX degradation in PMS activated system

Sulfate radical-based advanced oxidation processes (SR-AOPs) is considered as one of the most promising technologies for antibiotic pollution. In this study, a core-shell catalyst of cobalt-manganese oxide derived from CoMn-MOFs coating by MgAl-LDH (Co/Mn@LDH) was synthesized for peroxymonosulfate (PMS) activation to degrade sulfamethoxazole (SMX). Degradation efficiency of nearly 100% and a mineralization efficiency of 68.3% for SMX were achieved in Co/Mn@LDH/PMS system. Mn species and out shell MgAl-LDH greatly suppressed the cobalt ions leaching, which only 23 μg/L Co ions were detected by ICP after the reaction. SO4·- was identified as dominant reactive species in the system. Furthermore, the possible reactive sites of SMX were predicted by the density functional theory (DFT) calculations. And the intermediates of SMX were detected by LC-MS and the degradation pathway was proposed based on the results above. The ECOSAR results suggested the intermediates of SMX showed a relatively low toxicity compared to SMX, indicating huge potential of utilization of Co/Mn@LDH in SR-AOPs system.

Degradation of tetracycline by peroxymonosulfate activated with Mn0.85Fe2.15O4-CNTs: Key role of singlet oxygen

Tetracycline (TC) is a kind of electron-rich organic, and singlet oxygen (¹O₂) oxidative pathway-based advanced oxidation processes (AOPs) have represented outstanding selective degradation to such pollutants. In this paper, an excellent prepared strategy for ¹O₂ dominated catalyst was adopted. A catalyst composed of non-stoichiometric doping Mn-Fe bimetallic oxide supported on CNTs (0.3-Mn_0.85Fe_2.15O₄-CNTs) was synthesized and optimized by regulating the non-stoichiometric doping ratio of Mn & Fe and the loading amount of CNTs. Through optimization and control experiments, the optimized catalyst represented 94.9% of TC removal efficiency within 60 min in neutral condition under relatively low concentrations of Mn_0.85Fe_2.15O₄-CNTs (0.4 g/L) and PMS (0.8 mM). Through SEM and XRD characterization, Mn_0.85Fe_2.15O₄-CNTs was a hybrid of cubic Mn_0.85Fe_2.15O₄ uniformly dispersing on CNTs. By the characterization of XPS and FT-IR, more CO bonds and low-valent Mn (II) & Fe (II) appeared in Mn_0.85Fe_2.15O₄-CNTs. Reactive oxygen species (ROS) was determined by radical quenching experiments and electron spin resonance (EPR) spectroscopy, and ¹O₂ was verified to be the dominated ROS. The mechanism for PMS' activation was speculated, and more low-valent Mn (II) and Fe (II) contributed to the production of free-radical (•OH & SO₄^•-), while the reaction between PMS and the enhanced CO bond on Mn_0.85Fe_2.15O₄-CNTs played a crucial part in the generation of ¹O₂. In addition, through the comparative degradation of four different organics with distinct charge densities, the excellent selectivity of ¹O₂-based oxidative pathway to electron-rich pollutants was found. This paper supplied a good strategy to prepare catalyst for PMS activation to form a ¹O₂-dominated oxidative pathway.

Balancing Mass Transfer and Active Sites to Improve Electrocatalytic Oxygen Reduction by B,N Codoped C Nanoreactors

Mass transfer is critical in catalytic processes, especially when the reactions are facilitated by nanostructured catalysts. Strong efforts have been devoted to improving the efficacy and quantity of active sites, but often, mass transfer has not been well studied. Herein, we demonstrate the importance of mass transfer in the electrocatalytic oxygen reduction reaction (ORR) by tailoring the pore sizes. Using a confined-etching strategy, we fabricate boron- and nitrogen-doped carbon (B,N@C) electrocatalysts featuring abundant active sites but different porous structures. The ORR performance of these catalysts is found to correlate with diffusion of the reactant. The optimized B,N@C with trimodal-porous structures feature enhanced O₂ diffusion and better activity per heteroatomic site toward the ORR process. This work demonstrates the significance of the nanoarchitecture engineering of catalysts and sheds light on how to optimize structures featuring abundant active sites and enhanced mass transfer.

The optimized Fenton-like activity of Fe single-atom sites by Fe atomic clusters-mediated electronic configuration modulation

The performance optimization of isolated atomically dispersed metal active sites is critical but challenging. Here, TiO2@Fe species-N-C catalysts with Fe atomic clusters (ACs) and satellite Fe-N4 active sites were fabricated to initiate peroxymonosulfate (PMS) oxidation reaction. The AC-induced charge redistribution of single atoms (SAs) was verified, thus strengthening the interaction between SAs and PMS. In detail, the incorporation of ACs optimized the HSO5- oxidation and SO5·- desorption steps, accelerating the reaction progress. As a result, the Vis/TiFeAS/PMS system rapidly eliminated 90.81% of 45 mg/L tetracycline (TC) in 10 min. The reaction process characterization suggested that PMS as an electron donor would transfer electron to Fe species in TiFeAS, generating 1O2. Subsequently, the hVB+ can induce the generation of electron-deficient Fe species, promoting the reaction circulation. This work provides a strategy to construct catalysts with multiple atom assembly-enabled composite active sites for high-efficiency PMS-based advanced oxidation processes (AOPs).

MOFs-derived CuO-Fe3O4@C with abundant oxygen vacancies and strong Cu-Fe interaction for deep mineralization of bisphenol A

A novel CuO-Fe₃O₄ encapsulated in the carbon framework with abundant oxygen vacancies (CuO-Fe₃O₄@C) was successfully prepared by thermal conversion of Cu(OAc)₂/Fe-metal organic framework. The as-prepared catalyst exhibited excellent peroxymonosulfate (PMS) activation performance, good recyclability and fast magnetic separation. Under optimal conditions, the added BPA (60 mg/L) could be completely removed by CuO-Fe₃O₄@C/PMS system within 15 min with the degradation rate constant (k) of 0.32 min^-1, being 10.3 and 246.2 times that in CuO/PMS (0.031min^-1) and Fe₃O₄/PMS (0.0013 min^-1) system. A deep mineralization rate of BPA (＞80%) was achieved within 60 min. The results demonstrated the synergistic effect of bimetallic clusters, oxygen vacancies and carbon framework was a key benefit for the exposure of more active sites, the electron donor capacity and the mass transfer of substrates, thereby promoting the decomposition of BPA. Capture experiments and EPR indicated that ¹O₂ was the predominant reactive oxygen species (ROSs). The degradation routes of BPA and the activation mechanism of PMS were proposed. This study offers an opportunity to develop promising MOFs-derived hybrid catalysts with tailored structures and properties for the practical application of SR-AOPs.

Ultrafine oxygenophilic nanoalloys induced by multifunctional interstitial boron for methanol oxidation reaction

Interface construction is one of the most feasible approaches to optimize the physical and chemical properties of noble metal-based catalysts and consequently improve their catalytic performance. Herein, the design of effective reaction interfaces by bimetallic, trimetallic or polymetallic alloying has been extensively explored. In this research, metalloid boron (B) was alloyed within palladium-iridium (Pd-Ir) nanoalloy supported on nitrogen-doped graphene (NG) to promote the methanol oxidation reaction (MOR) in alkaline media. Being benefited from this, the optimum Pd7IrBx/NG catalyst exhibited enhanced EOR activity mass activity (1141.7 mA mg-1) and long-term stability (58.2 % current density retention rate after 500 cycles of cyclic voltammetry). The mechanism was further studied by electrochemical experiments and characterization, which highlighted that the multifunctional effect of electronic effect and strain effect and kinetic optimization induced by boron doping played a very positive role on MOR.

Core-shell magnetic CFO@COF composites toward peroxymonosulfate activation for degradation of sulfamethoxazole from aqueous solution: A comparative study and mechanistic consideration

A core-shell covalent organic framework encapsulated Co1.2Fe1.8O4 magnetic particles (CFO@COF) was designed and prepared successfully to activate peroxymonosulfate (PMS) for sulfamethoxazole (SMX) degradation. It displays amazing catalytic reactivity since the unique interior structure and synergistic effect between COF shell and CFO core, reaching 99.8% removal of SMX (10 mg/L) within 30 min and 90.8% TOC removal. The synergy between bimetals vests high reactivity to CFO core. And the outer COF shell can stabilize the CFO core under intricate reaction conditions to restrain the leaching of Co ions (decreased from 0.75 to 0.25 mg/L). Further investigation compared the activation mechanism in two different system, CFO/PMS system and CFO@COF/PMS system. The result showed that the radical mechanism controlled by SO4⋅- guided the SMX degradation in CFO/PMS system whereas the 1O2 played a pivotal role in CFO@COF/PMS system called non-radical leading. The influences of various factors on degradation experiments and SMX degradation pathway were also studied. Most importantly, risk assessment in CFO@COF/PMS/SMX system was estimated via "ecological structure activity relationships". In most case, the toxicities of intermediates were lower than the initial samples, which confirmed the effectiveness of CFO@COF/PMS/SMX system in the reduction of toxicity of SMX.

Valorization of ball-milled waste red mud into heterogeneous catalyst as effective peroxymonosulfate activator for tetracycline hydrochloride degradation

Red mud (RM), a kind of iron-rich industrial waste produced in the alumina production process, can be utilized as a potential iron-based material for the removal of refractory organic pollutants from wastewater in advanced oxidation processes (AOPs). In this work, high-iron RM (rich in iron) was activated in a ball mill and applied as an effective activator of peroxymonosulfate (PMS) for tetracycline hydrochloride (TC-HCl) degradation. Compared with that of unmilled RM (69.7%), the TC-HCl decomposition ratios of ball-milled RM (BM-RM) (72.2%-92.0%) were all improved in the presence of PMS. Systematic characterization suggested that ball milling could optimize the physicochemical properties of RM, such as increased surface area, increased oxygen vacancies, enhanced electrical conductivity, and increased exposure of Fe(II) sites, all of which could effectively improve RM for PMS activation to degrade TC-HCl. The quenching experiments and electron paramagnetic resonance technique revealed that ¹O₂ and SO₄·^- contributed dominantly to the TC-HCl degradation. Ultra performance liquid chromatography mass spectrometry analysis combined with density functional theory calculation revealed that the degradation pathways of TC-HCl were driven by hydroxylation, N-demethylation and dehydration in BM-RM/PMS system. Based on quantitative structure-activity relationship prediction using the Toxicity Estimation Software Tool software, the toxicity of almost all intermediates was significantly reduced. An obvious inhibition effect on TC-HCl was occurred in the presence of Cl^-, whereas the presences of NO₃^- and SO₄^2- had little effect. However, HCO₃^- improved TC-HCl removal efficiency. BM-RM had a wide working pH range (pH = 3-11) and showed good stability and reusability in use. Overall, this work not only offers a simple and promising approach to improve the catalytic activity of RM, but also opens new insights into the ball-milled RM as an effective PMS activator for wastewater treatment.

Recent Advancements in MOF/Biomass and Bio-MOF Multifunctional Materials: A Review

Metal–organic frameworks (MOFs) and their derivatives have delivered perfect answers in detection, separation, solving water and electromagnetic pollution and improving catalysis and energy storage efficiency due to their advantages including their highly tunable porosity, structure and versatility. Recently, MOF/biomass, bio-MOFs and their derivatives have gradually become a shining star in the MOF family due to the improvement in the application performance of MOFs using biomass and biomolecules. However, current studies lack a systematic summary of the synthesis and advancements of MOF/biomass, bio-MOFs and their derivatives. In this review, we describe their research progress in detail from the following two aspects: (1) synthesis of MOF/biomass using biomass as a template to achieve good dispersion and connectivity at the same time; (2) preparing bio-MOFs by replacing traditional organic linkers with biomolecules to enhance the connection stability between metal ions/clusters and ligands and avoid the formation of toxic by-products. This enables MOFs to possess additional unique advantages, such as improved biocompatibility and mechanical strength, ideal reusability and stability and lower production costs. Most importantly, this is a further step towards green and sustainable development. Additionally, we showcase some typical application examples to show their great potential, including in the fields of environmental remediation, energy storage and electromagnetic wave absorption.