Zeolitic imidazolate framework-supported Prussian blue analogues as an efficient Fenton-like catalyst for activation of peroxymonosulfate

A one-stone-two-birds strategy for cellulose dissolution, regeneration, and functionalization as a photocatalytic composite membrane for wastewater purification

Photocatalytic membranes integrate membrane separation and photocatalysis to deliver an efficient solution for water purification, while the top priority is to exploit simple, efficient, renewable, and low-cost photocatalytic membrane materials. We herein propose a facile one-stone-two-birds strategy to construct a multifunctional regenerated cellulose composite membrane decorated by Prussian blue analogue (ZnPBA) microspheres for wastewater purification. The hypotheses are that: 1) ZnCl2 not only serves as a cellulose solvent for tuning cellulose dissolution and regeneration, but also functions as a precursor for in-situ growth of spherical-like ZnPBA; 2) More homogeneous reactions including coordination and hydrogen bonding among Zn2+, [Fe(CN)6]3- and cellulose chains contribute to a rapid and uniform anchoring of ZnPBA microspheres on the regenerated cellulose fibrils (RCFs). Consequently, the resultant ZnPBA/RCM features a high loading of ZnPBA (65.3 wt%) and exhibits excellent treatment efficiency and reusability in terms of photocatalytic degradation of tetracycline (TC) (90.3 % removal efficiency and 54.3 % of mineralization), oil-water separation efficiency (>97.8 % for varying oils) and antibacterial performance (99.4 % for E. coli and 99.2 % for S. aureus). This work paves a simple and useful way for exploiting cellulose-based functional materials for efficient wastewater purification.

Peroxymonosulfate activation by iron-cobalt bimetallic phosphide modified nickel foam for efficient dye degradation

Novel catalysts with multiple active sites and rapid separation are required to effectively activate peroxymonosulfate (PMS) for the removal of organic pollutants from water. Therefore, an integrated catalyst for PMS activation was developed by directly forming Co-Fe Prussian blue analogs on a three-dimensional porous nickel foam (NF), which were subsequently phosphorylated to obtain cobalt-iron bimetallic phosphide (FeCoP@NF). The FeCoP@NF/PMS system efficiently degraded dye wastewater within 20 min. The system exhibited excellent catalytic degradation over a broad pH range and at high dye concentrations due to the presence of unique asymmetrically charged Coa+ and Pb- dual active sites formed by cobalt phosphides within FeCoP@NF. These active sites significantly enhanced the catalytic activity of PMS. The activation mechanism of PMS involves phosphorylation that accelerates electron transfer from FeCoP@NF to PMS, to generate SO4·-, ·OH, O2·-, and 1O2 active species. Three-dimensional FeCoP@NF could be readily recycled and showed good stability for PMS activation. In this study, a highly efficient, stable, and readily recyclable integrated catalyst was developed. This catalyst system effectively resolves the separation and recovery issues associated with conventional powder catalysts and has a wide range of potential applications in wastewater treatment.

Cerium oxide /Co-Co Prussian blue analogue composite catalyst for enhanced peroxymonosulfate activation for effective removal of tetracycline hydrochloride from water

In this paper, a novel CeO2/Co3[Co(CN)6]2 (CeO2/PBACo-Co) composite was prepared with co-precipitation and utilized to activate peroxymonosulfate (PMS) to eliminate tetracycline hydrochloride (TCH). Catalyst screening showed that the composite with a CeO2:PBACo-Co mass ratio of 1:5 (namely, 0.2-CeO2/PBACo-Co) had the best performance. The degradation efficiency of TCH in 0.2-CeO2/PBACo-Co/Oxone system was investigated. The experimental results illustrated that 98% of 50 mg/L TCH and 48.5% of TOC were degraded by 50 mg/L 0.2-CeO2/PBACo-Co and 400 mg/L Oxone within 120 min at 25 °C and initial pH 5.3. Recycling studies showed that the elimination rate of TCH can still achieve 85.8% after five cycles, suggesting that 0.2-CeO2/PBACo-Co composite processes good reusability. Trapping experiments and EPR tests revealed that the reaction system produced multiple active species (1O2, O2•-, SO4•-, and •OH). We proposed the catalytic mechanism of 0.2-CeO2/PBACo-Co for PMS activation, which mainly involves the promoted Co3+/Co2+ cycle by Ce3+ donated electrons. These results indicate that CeO2/PBACo-Co composite is an effective catalyst for wastewater remediation.

Nickel-doped red mud-based Prussian blue analogues heterogeneous activation of H2O2 for ciprofloxacin degradation: waste control by waste

Red mud (RM) is a typical bulk solid waste with Fe/Al/Si/Ca-rich characteristics that has been used to prepare various heterogeneous catalysts such as iron-based catalysts and supported catalysts. Prussian blue analogues (PBA) is a low-cost, environmentally friendly, and active site rich iron-based metal organic framework, but its catalytic properties are adversely affected by their easy aggregation. In this study, nickel-doped RM-based PBA (RM-Ni PBA) was synthesized by acid dissolution-coprecipitation method for the degradation of ciprofloxacin (CIP). The characterization showed that RM-Ni PBA was a material with excellent dispersibility, large specific surface area, and abundant active sites. The degradation results showed that the removal efficiency of CIP in the RM-Ni PBA/H2O2 system was 16.63, 1.78, and 1.81 times that of RM, RM-PB, and Ni PBA, respectively. It was found that 1O2 was the main reactive oxygen species (ROS) dominated the degradation process, and its formation was accompanied by the mutual conversion of Ni(II)/Fe(II) and Ni(III)/Fe(III). Notably, the degradation process maintained a satisfactory efficiency over a wide pH range (3-9) and exhibited strong anti-interference ability against impurities such as Cl-, SO42-, and NO3-. The components and contents of RM-Ni PBA remained relatively stable during the degradation process. In addition, the degradation intermediates of CIP were identified, and possible degradation pathways were proposed. This study is expected to provide theoretical basis and technical guidance for the application of RM-based heterogeneous catalyst in the treatment of antibiotic wastewater.

3D Pathways Enabling Highly-Efficient Lithium Reservoir for Fast-Charging Batteries

Enhancing the mobility of lithium-ions (Li+) through surface engineering is one of major challenges facing fast-charging lithium-ion batteries (LIBs). In case of demanding charging conditions, the use of a conventional artificial graphite (AG) anode leads to an increase in operating temperature and the formation of lithium dendrites on the anode surface. In this study, a biphasic zeolitic imidazolate framework (ZIF)-AG anode, designed strategically and coated with a mesoporous material, is verified to improve the pathways of Li+ and electrons under a high charging current density. In particular, the graphite surface is treated with a coating of a ZIF-8-derived carbon nanoparticles, which addresses sufficient surface porosity, enabling this material to serve as an electrolyte reservoir and facilitate Li+ intercalation. Moreover, the augmentation in specific surface area proves advantageous in reducing the overpotential for interfacial charge transfer reactions. In practical terms, employing a full-cell with the biphasic ZIF-AG anode results in a shorter charging time and improved cycling performance, demonstrating no evidence of Li plating during 300 cycles under 3.0 C-charging and 1.0 C-discharging. The research endeavors to contribute to the progress of anode materials by enhancing their charging capability, aligning with the increasing requirements of the electric vehicle applications.

Effective activation of peroxymonosulfate by CoCr-LDH for removing organic contaminants in water: from lab-scale to practical applications

In this study, CoCr layered double hydroxide material (CoCr-LDH) was prepared and used as an effective catalyst for peroxymonosulfate (PMS) activation to degrade organics in water. The prepared CoCr-LDH material had a crystalline structure and relatively porous structure, as determined by various surface analyses. In Rhodamine B (RhB) removal, the most outstanding PMS activation ability belongs to the material with a Co:Cr molar ratio of 2:1. The removal of RhB follows pseudo-first-order kinetics (R2 > 0.99) with an activation energy of 38.23 kJ/mol and efficiency of 98% after 7 min of treatment, and the total organic carbon of the solution reduced 47.2% after 10 min. The activation and oxidation mechanisms were proposed and the RhB degradation pathways were suggested with the key contribution of O2•- and 1O2. Notably, CoCr-LDH can activate PMS over a wide pH range of 4 - 9, and apply to a wide range of organic pollutants and aqueous environments. The material has high stability and good recovery, which can be reused for 5 cycles with a stable efficiency of above 88%, suggesting a high potential for practical recalcitrant water treatment via PMS activation by heterogeneous catalysts.

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.

Simultaneous degradation of binary fluoroquinolone antibiotics by B and N in-situ self-doped guar gum hydrogel

Using guar gum (GG) as the raw material and borax (B) as the cross-linker, zeolitic imidazolate framework-8 (ZIF-8) was in-situ loaded into the 3D network of GG hydrogel, forming a highly efficient catalytic material GG-B-ZIF-8 combined with a subsequent low-temperature calcination process. In GG-B-ZIF-8 activated peroxymonosulfate (PMS) system, binary norfloxacin (NOR) and ciprofloxacin (CIP) could be removed simultaneously, with the degradation efficiency of >99.9% within 1 h. This system was adaptable to a wide pH range of 3.0-9.0, and was also highly resistant to 5-20 mM Cl- and 10-40 mg/L humic acid. The degradation process was dominated by free radical O2•-, non-radical 1O2 and electron transfer, with eleven degradation products identified for NOR and nine for CIP via eight possible degradation pathways. Finally, the potential eco-toxicity of NOR, CIP and degradation intermediates was evaluated using the ECOSAR method.

Optimization of iron-ZIF-8 catalysts for degradation of tartrazine in water by Fenton-like reaction

Optimization of iron zeolitic imidazole framework-8 (FeZIF-8) nanoparticles, as heterogeneous catalysts, were synthesized and evaluated by the Fenton-like reaction for to degrade tartrazine (Tar) in aqueous environment. To achieve this, ZIF-8 nanoparticles were modified with different iron species (Fe2+ or Fe3O4), and subsequently assessed through the Fenton-like oxidation. The effect of different parameters such as the concentration of hydrogen peroxide, the mass of catalyst and the contact time of reaction on the degradation of Tar by Fenton-like oxidation was studied by using the Box-Behnken design (BBD). The BBD model indicated that the optimum catalytic conditions for Fenton-like reaction with an initial pollutant concentration of 30 ppm at pH 3.0 were T = 40 °C and 12 mM of H2O2, 2 g/L of catalyst and 4 h of reaction. The maximum Tar conversion value achieved with the best catalyst, Fe1ZIF-8, was 66.5% with high mineralization (in terms of decrease of total organic carbon - TOC), 44.2%. To assess phytotoxicity, the germination success of corn kernels was used as an indicator in the laboratory. The results show that the catalytic oxidation by Fenton-like reaction using heterogeneous iron ZIF-8 catalysts is a viable alternative for treating contaminated effluents with organic pollutants and highlighted the importance of the validation of the optimized experimental conditions by mathematical models.

Prussian blue analogues derived magnetic FeCo@GC material as high-performance metallic peroxymonosulfate activators to degrade tetrabromobisphenol A over a wide pH range

Metal-organic frame (MOF) materials can effectively degrade organic pollutants, whereas the MOF is rapidly hydrolysed in water and has poor stability and low reusability. However, in the current advanced oxidation process (AOP) system, the removal effect of pollutants under alkaline condition is not ideal. In this study, a magnetic composite material derived from MOF was synthesised and used as a new catalyst for rapid degradation of tetrabromobisphenol A (TBBPA). Compared to precarbonisation, FeCo@GC formed a conductive graphite carbon skeleton, retained the complete rhombododecahedron structure, had a larger specific surface area and provided more active sites for peroxymonosulfate (PMS) activation. The target pollutant TBBPA (20 mg/L) was completely degraded within 30 min, and the mineralisation rate reached 40.98% in the FeCo@GC (150 mg/L) and PMS (1 mM) systems, owing to the synergistic interaction between Fe, Co and graphite carbon. The reactive oxygen species (ROS) involved in the reaction were determined to be SO4•-, ·OH, 1O2 and O2•- by electron paramagnetic resonance and free radical scavenging experiments, and the 1O2 played a dominant role. Based on the results of LC-MS analysis results, the main degradation pathways of TBBPA involve three mechanisms: the debromination reaction, hydroxylation and cleavage of the benzene ring. In addition, compared with previous AOP systems, FeCo@GC/PMS overcomes the disadvantage of poor degradation effect of TBPPA under alkaline conditions, has a wide range pH (3-11) application and has the best effect on TBBPA degradation under alkaline conditions. FeCo@GC has an excellent cycle performance, with a removal rate of re-calcined material of 88.52% after five cycles. Therefore, FeCo@GC can be used as a promising and efficient catalyst for removing environmental organic pollutants.

Research progress of metal-organic framework-based material activation of persulfate to degrade organic pollutants in water

The rapid development of industry in recent years has led to the introduction of serious pollutants into water bodies, and there is an urgent need for efficient organic degradation technologies. At present, selective peroxynitrite (PS) oxidation (SR-AOPs) is an effective way to treat pollutants in water bodies, and it is necessary to select a suitable material for the activation of peroxynitrite. Metal-organic frameworks (MOFs), with their tunable structure, large specific surface area, and tunable ligand molecules exhibit excellent reactivity and catalytic performance in the activation of persulfate. With MOF-based materials for PS activation as a novel advanced oxidation technology, this study reviews MOFs and their composites and derived materials. The current research status of activated persulfate for the treatment of organic pollutants in water, the influence of different systems on the degradation performance are discussed, and the activation and degradation mechanisms are discussed; the problems of the above materials in the degradation of organic pollutants are summarized, and research directions based on the coupled activated persulfate system of MOF materials are proposed.

High yielded Co-C derived from polyester-Cobalt carbothermal reduction for efficient activation of peroxymonosulfate to degrade levofloxacin

A kind of high yield and recyclable Cobalt-Carbon composite (Zn₁Co₅/P_nC) was prepared by carbothermal reduction process, in which the cobalt acetate and zinc acetate were considered as Zn and Co precursors, and the polyester waste was evolved as the carbon precursor. The morphology, structure and composition of the composite were characterized using scanning electron microscopy, X-ray diffraction and X-ray photoelectron spectroscopy. Results showed that evaporation of zinc contributed to the formation of porous carbon structure, and the Co nanoparticles were wrapped and protected by the porous carbon matrix. The Zn₁Co₅/P_nC activated peroxymonosulfate (PMS) system (Zn₁Co₅/P_nC/PMS) was constructed to degrade the levofloxacin (LEV). The activity and mechanism of LEV degradation was understood. The LEV degradation efficiency was high to 96.60% within 90 min in the presence of Zn₁Co₅/P₄C. Moreover, the Zn₁Co₅/P₄C still maintained favorable PMS activation performance after five-cycle runs. The results show that the Zn₁Co₅/P₄C played positive role in activating the PMS, it may be due to the facts that the polyester derived carbon could supported the Co while the evaporated Zn could increase the surface area of Zn₁Co₅/P₄C, leading to the increased activity. The possible degradation pathways were proposed by identifying the intermediate products through liquid chromatography-mass spectrometry analysis. This study put forward a promising method to use polyester waste to synthesize high yield cobalt-carbon composite for degrading the antibiotic in wastewater.

Peroxymonosulfate activation by magnetic CoNi-MOF catalyst for degradation of organic dye

In this work, Fe₃O₄/CoNi-MOF was synthesized by a simple solvothermal method. The catalytic performance of 0.2-Fe₃O₄/CoNi-MOF toward PMS activation was studied by degradation of 20 mg/L methylene blue (MB). The results indicated that 0.2-Fe₃O₄/CoNi-MOF had good catalytic ability, the removal rate of MB was 99.4% within 60 min with 125 mg/L PMS and 150 mg/L catalyst. Quenching experiment and electron paramagnetic resonance (EPR) analysis revealed that the singlet oxygen (¹O₂), superoxide radical (•O₂^-) and sulfate radical (SO₄^•-) played a crucial role in the catalytic degradation process. Meantime, mechanism of PMS activation by 0.2-Fe₃O₄/CoNi-MOF was proposed, the electrons donated by Fe²⁺ can also enhance the Co-Ni cycles. In conclusion, Fe₃O₄/CoNi-MOF composite catalyst has the advantages of simple preparation, excellent catalytic activity and reusability, which is an effective catalyst for water pollution control.

Overestimation of 1O2 role in N-doped carbon materials/peroxymonosulfate system: The misleading of furfuryl alcohol quenching effect

Singlet oxygen (¹O₂) is frequently observed in persulfate-based advanced oxidation processes (PS-AOPs), however its significance in the removal of organic compounds is debatable. To evaluate the role of ¹O₂, some organic pollutants that have been proven to be successfully degraded by ¹O₂ in earlier research were selected as the targeted pollutants of this study. In the activation of peroxymonosulfate (PMS) using Co-BTC (a type of metal-organic framework)/melamine derived nitrogen-doped carbon material (Co-BTC/10MNC) as the catalyst, ¹O₂ and surface-bound SO₄^•- are discovered, however only surface-bound SO₄^•- was the dominant species. The degree of inhibition of furfuryl alcohol (FFA) on the removal of organics is reliant on the reaction rates of SO₄^•- and organics, rather than on the quenching impact of FFA on ¹O₂. The lower k_SO4•- organics have, the easier it is for FFA to inhibit their removal. In short, the quenching effect of FFA is not solid evidence to identify ¹O₂. Besides, it is found that the influence of HCO₃^- is related to the second order reaction rate constant (k_HCO3•) between HCO₃^• and organics, implying that the selective removal of some organics is due to that corresponding inorganic radicals (Cl^•, NO₃^•, HCO₃^• or HPO₄^•-) have good ability to degrade these organics, rather than ¹O₂ as the key reactive oxygen species.

Adsorption and fenton-like oxidation of ofloxacin in wastewater using hybrid MOF bimetallic Fe/Ni nanoparticles

Since ofloxacin (OFX) is one of many common antibiotics, which effluxes into aquatic environment in relatively high concentration, it has become of significant environmental concern due to the potential for increased antibiotic resistance. In this study, an innovative functional Fe/Ni@ZIF-8 composite was successfully used for the Fenton-like oxidation of OFX, with a OFX removal efficiency >98% under optimal conditions. FTIR analysis confirmed that OFX removal occurred via adsorption to Fe/Ni@ZIF-8 by a combination of π-π bond intercalation and electrostatic interaction, while XPS revealed that the Fe/Ni NPs in Fe/Ni@ZIF-8 were also involved in oxidation. Furthermore, LC-MS analysis identified the presence of several OFX degradation products post exposure, which indicted that Fe/Ni NPs in Fe/Ni@ZIF-8 reacted with H₂O₂ to form •OH, leading to Fenton-like oxidation of OFX. Thus overall, OFX removal by Fe/Ni@ZIF-8 involved both adsorption to ZIF-8 and Fenton-like oxidation by Fe/Ni NPs. A synergistic mechanism for OFX removal by Fe/Ni@ZIF-8 was thus proposed. The removal efficiency of the synthesized catalysts remained high (above 65%) even after a 5th reuse cycle, which reflected the high stability of Fe/Ni@ZIF-8. Overall, this study demonstrated that Fe/Ni@ZIF-8 had significant potential for the removal of OFX from wastewaters with a removal efficiency >90%.

Peroxymonosulfate activation through ferromagnetic bimetallic spinel sulfide composite (Fe3O4/NiCo2S4) for organic pollutant degradation

Spinel sulfides are a good candidate as heterogeneous catalysts for wastewater treatment through peroxymonosulfate (PMS) activation. In this paper, magnetic Fe₃O₄/NiCo₂S₄ composite was successfully synthesized by hydrothermal method. Catalyst screening displayed that the composite catalyst with a Fe₃O₄:NiCo₂S₄ molar ratio of 1:3 (i.e.,0.33-Fe₃O₄/NiCo₂S₄) is the most optimal. The results showed that 0.33-Fe₃O₄/NiCo₂S₄ composite catalyst had superior catalytic activity, achieving 99.8%,65.1% and 40.7% of RhB, COD and TOC removals within 30 min with 180 m g/L PMS and 75 mg/L catalyst. We proposed a potential catalytic mechanism of PMS activation by Fe₃O₄/NiCo₂S₄ in two aspects. On the one hand, sulfur species such as S^2- and S₂^2- enhance the Co³⁺/Co²⁺, Ni³⁺/Ni²⁺ and Fe³⁺/Fe²⁺ cycles on Fe₃O₄/NiCo₂S₄ surface. On the other hand, there is the synergistic effect of Co³⁺/Co²⁺, Ni³⁺/Ni²⁺ and Fe³⁺/Fe²⁺ cycles in activating PMS. Overall, owing to its excellent catalytic activity, reusability, and easy recovery, Fe₃O₄/NiCo₂S₄ is a potentially useful catalyst for remediation of contaminated water.

Recent progress of functional metal-organic framework materials for water treatment using sulfate radicals

Human health is being threatened by the ever-increasing water pollution. Sulfate radical (SO₄^•-)-based advanced oxidation processes (SR-AOPs) are rapidly being developed and gaining considerable attention due to their high oxidation potential and selectivity as a way to purify water by degrading organic contaminants in it. Among the catalytic materials that can activate the precursor to generate SO₄^•-, metal-organic frameworks (MOFs) are the most promising heterogeneous catalytic material in SR-AOPs because of their various structure possibilities, large surface area, ordered porous structure, and regular activation sites. Herein, an in-depth overview of MOFs and their derivatives for water purification with SR-AOPs is provided. The latest studies on pristine MOFs, MOF composites, and MOF derivatives (metal oxides, metal-carbon hybrids, and carbon materials) are summarized. The mechanisms of decomposition of pollutants in water via radical and non-radical pathways are also discussed. This review suggests future research directions for water purification through MOF-based SR-AOP.

Strategies for improving the catalytic activity of metal-organic frameworks and derivatives in SR-AOPs: Facing emerging environmental pollutants

As persulfate activator, Metal organic frameworks (MOFs) and derivatives are widely concerned in degradation of emerging environmental pollutants by advanced oxygen technology dominated by sulfate radical () (SR-AOPs). However, the poor stability and low catalytic efficiency limit the performance of MOFs, requiring multiple strategies to further enhance their catalytic activity. The aim of this paper is to improve the catalytic activity of MOFs and their derivatives by physical and chemical enhancement strategies. Physical enhancement strategies mainly refer to the activation strategies including thermal activation, microwave activation and photoactivation. However, the physical enhancement strategies need energy consumption and require high stability of MOFs. As a substitute, chemical enhancement strategies are more widely used and represented by optimization, modification, composites and derivatives. In addition, the identification of reactive oxygen species, active site and electron distribution are important for distinguishing radical and non-radical pathways. Finally, as a new wastewater treatment technology exploration of unknown areas in SR-AOPs could better promote the technology development.

Enhancement of the Catalytic Activity of Double Metal Cyanides for the Oxidation of Styrene by the Presence of Included Alcohols

In recent years, people have focused on the development of simple and efficient heterogeneous catalysts for the styrene epoxidation reaction. In this work, a FeCo double metal cyanide (DMC) was modified with C1 to C6 linear alcohols, and the prepared materials were used to catalyze the reaction of styrene epoxidation in various solvents. It is noteworthy that the styrene conversion is mainly affected by modification with alcohols, while the selectivity in styrene oxide (SO) is obviously influenced by the solvent. FeCo DMC along with MeOH exhibits the best catalytic performance, with a conversion rate of 96% and a SO selectivity of 86%, in N,N-dimethylformamide (DMF) solvent. Various physical and chemical methods were used to analyze the structures and compositions of the materials. To clarify the mechanism of the improvement, we set up an original approach to investigate the kinetics of the adsorption process between the oxidant and the catalyst, using isothermal titration calorimetry (ITC). The obtained results illustrate that the adsorption process of the oxidant on the surface of FeCo DMC can be dramatically promoted by the presence of MeOH. Such a difference in adsorption thus explains the significant improvement of its catalytic activity by modification with MeOH. This study thus provides a new fundamental understanding of DMC catalysts for the styrene epoxidation reaction.

High yield M-BTC type MOFs as precursors to prepare N-doped carbon as peroxymonosulfate activator for removing sulfamethazine: The formation mechanism of surface-bound SO4•- on Co-Nx site

M-BTCs (M = Fe, Co and Mn)/melamine were used to prepare N-doped carbon materials, and their performances as activator of peroxymonosulfate (PMS) for sulfamethazine (SMZ) removal were compared. M-BTC type metal-organic frameworks (MOFs) were synthesized under room temperature, with their yield about 7.5 times of ZIF-67 which is the most used MOFs to prepare N-doped carbon materials as the catalyst of persulfate-based advanced oxidation processes. Co-BTC/melamine derived N-doped carbon materials (Co-BTC/5MNC) performed the best, even better than that of ZIF-67 derived N-doped carbon materials. Initial pH (3-9), 0-10 mM inorganic anions (Cl^-, NO₃^-, HCO₃^- and H₂PO₄^2-) and humic acid (5 and 10 mg/L) had no obvious inhibition on SMZ removal with Co-BTC/5MNC as catalyst. The results of both X-ray photoelectron spectroscopy and density functional theory (DFT) calculations indicated that N-coordinated cobalt single atom site (Co-N_x) was the possible active site of Co-BTC/5MNC. Importantly, surface-bound SO₄^•- was identified as the dominant reactive oxygen species for SMZ removal. The SO₄^•- generated through the charge transfer between PMS and catalyst, and was tightly adsorbed on Co-N_x site.

Bicarbonate-enhanced iron-based Prussian blue analogs catalyze the Fenton-like degradation of p-nitrophenol

P-nitrophenol (PNP), a widely used compound, is harmful to the environment and human health. In this study, four iron-based Prussian blue analogs (PBAs) were prepared by coprecipitation (Co-Fe PBA, Mn-Fe PBA, Cu-Fe PBA and Fe-Fe PBA). The Co-Fe PBA exhibited high peroxymonosulfate (PMS) activation performance for PNP degradation, removing over 90% of PNP in 60 min at an optimal pH of 7, temperature at 30 ℃, initial concentration of 20 mg/L, PBA dose of 0.2 g/L and PMS dose of 1 g/L. The physicochemical properties of the Co-Fe PBA were investigated by various characterization methods. The catalytic activity of PBA and the influence of various process parameters and water quality on the catalytic reaction were investigated to elucidate the mechanism of p-nitrophenol degradation by PBA-activated persulfate. Moreover, the mechanism of accelerated degradation of PNP under HCO₃^- conditions and the role of major reactive oxides were determined by EPR measurement methods and free radical trapping experiments. HCO₃^- was found to directly activate PMS to produce reactive oxygen species, and ¹O₂, ∙OH and SO₄^∙- were all greatly increased. This work presents a promising green heterogeneous catalyst for the degradation of emerging contaminants (ECs) in real wastewater with natural organic matter and coexisting anions by PMS activation.

The synthesis of zeolitic imidazolate framework/prussian blue analogue heterostructure composites and their application in supercapacitors

ZIF-67/PBA heterostructure composites was prepared by the ion-exchange method with ZIF-67 nanoparticles as host MOFs. The electrochemical performance of the ZIF-67/PBA heterostructure composites improved after low-temperature calcination.

Environmentally Benign Formation of Nickel Hexacyanoferrate-Derived Mesoframes for Heterogeneous Catalysis

The tetramethylammonium hydroxide (TMAH)-controlled alkaline etching of nickel hexacyanoferrate (NiHCF) mesocrystals is explored. The alkaline etching enables the formation of hollow framework structures with an increased surface area, the exposure of active Ni and Fe sites and the retention of morphology. The ambient reaction conditions enable the establishment of a sustainable production. Our work reveals novel perspectives on the eco-friendly synthesis of hollow and colloidal superstructures for the efficient degradation of the organic contaminants rhodamine-B and bisphenol-A. In the case of peroxomonosulfate (PMS)-mediated bisphenol-A degradation, the rate constant of the etched mesoframes was 10,000 times higher indicating their significant catalytic activity.