Unveiling the Role of Strong Metal-Support Interactions in Gold-Catalyzed CO Oxidation on MnO2 Polymorphs

The effectiveness of gold (Au)-based catalysts in CO oxidation is significantly influenced by strong metal-support interactions with surface oxygen structures, the mechanisms of which remain elusive. To investigate this property, we selected γ-MnO2, featuring Mn(-O-)2Mn and Mn-O-Mn structural motifs, and β-MnO2, characterized by Mn-O-Mn linkages, as support materials. The CO oxidation process was investigated by fabricating Au nanoparticles supported on these two MnO2 polymorphs. Our findings reveal that Au supported on β-MnO2 substantially enhanced CO oxidation, in stark contrast to the inhibitory effect observed with Au on γ-MnO2. Using operando diffuse reflectance infrared Fourier transform spectroscopy coupled with mass spectrometry, we detected an increase in the production of surface-adsorbed oxygen following Au deposition on β-MnO2. Conversely, Au supported on γ-MnO2 resulted in a diminished capacity for surface oxygen adsorption. The presence of Au+ and Mn2+ ions was identified as pivotal for CO oxidation. Moreover, the engagement of the Mn(-O-)2Mn structure in the reaction was impaired after Au loading on γ-MnO2, and the regeneration of the Mn-O-Mn linkage was similarly hindered. We propose a mechanism for the interactions between Au and the oxygen species associated with Mn(-O-)2Mn and Mn-O-Mn structures on MnO2, offering insights into the divergent catalytic behaviors exhibited by different MnO2 polymorphs.

Synthetic and analytical considerations for the preparation of amorphous metal-organic frameworks

Metal-organic frameworks (MOFs) are hybrid porous materials presenting several tuneable properties, allowing them to be utilised for a wide range of applications. To date, focus has been on the preparation of novel crystalline MOFs for specific applications. Recently, interest in amorphous MOFs (aMOFs), defined by their lack of correlated long-range order, is growing. This is due to their potential favourable properties compared to their crystalline equivalents, including increased defect concentration, improved processability and gas separation ability. Direct synthesis of these disordered materials presents an alternative method of preparation to post-synthetic amorphisation of a crystalline framework, potentially allowing for the preparation of aMOFs with varying compositions and structures, and very different properties to crystalline MOFs. This perspective summarises current literature on directly synthesised aMOFs, and proposes methods that could be utilised to modify existing syntheses for crystalline MOFs to form their amorphous counterparts. It outlines parameters that could discourage the ordering of crystalline MOFs, before examining the potential properties that could emerge. Methodologies of structural characterisation are discussed, in addition to the necessary analyses required to define a topologically amorphous structure.

Mn-MOF derived manganese sulfide as peroxymonosulfate activator for levofloxacin degradation: An electron-transfer dominated and radical/nonradical coupling process

Recently, transition metal sulfides have attracted much attention due to their better catalytic capacities as peroxymonosulfate (PMS) activator than their metal oxide counterparts. However, the systematic studies on PMS activation using transition metal sulfides are still lacking. In this work, manganese sulfide (MnS) materials were synthesized via a MOFs-derived method and utilized for PMS activation to degrade levofloxacin (LVF) in water for the first time. As expected, MnS exhibited remarkable LVF degradation efficiency by PMS activation, which was distinctly higher than Mn₂O₃. The results of quenching experiments, electro spin resonance identification and electrochemical tests indicated that electron-transfer progress was the dominant mechanism in α-MnS/PMS system. Meanwhile, the presence of ¹O₂ and radicals further became the removal of LVF by α-MnS/PMS system into a radical/nonradical coupling process. The superior electrical conductivity of α-MnS than α-Mn₂O₃ was revealed by DFT calculations, which resulted in the higher catalytic capacity of α-MnS. The result of XPS also indicated the S species in MnS accelerated the recycle of Mn(IV)/Mn(II) and then promoted the generation of radicals. Furthermore, the influence of various environmental conditions on LVF removal and the reusability of α-MnS were also investigated, which demonstrated the high application potential of α-MnS/PMS system. Finally, six possible pathways of LVF oxidation in the system were proposed based on the identified byproducts and their ecotoxicity was evaluated with ECOSAR method. This work promotes the fundamental understanding of PMS activation by α-MnS and provides useful information for practical application of manganese sulfide in water treatment.

Mutual inhibition effects on the synchronous conversion of benzene, toluene, and xylene over MnOx catalysts

Advancing the practical application of catalytic oxidation technology demands for illustrating the synchronous conversion behavior of various volatile organic compounds (VOCs) over catalysts. Here, the mutual effects of benzene, toluene and xylene (BTX) were examined for their synchronous conversion on the surface of the MnO₂ nanowire. Competitive adsorption of xylene (absorption energy (E_ads): -0.889 eV) facilitated its prior conversion and impeded the oxidization of toluene and benzene over the catalyst. The turnover frequencies were 0.52 min^-1 (benzene), 0.90 min^-1 (toluene) and 2.42 min^-1 (xylene) for mixed BTX conversion over the MnO₂. Doping MnO₂ with K⁺, Na⁺ and Ca²⁺ could enhance its ability to oxidize the individual VOCs but did not alter the conversion mechanism of mixed BTX over the catalyst. When reducing the competitive effects in the adsorption of BTX, the oxidation performance of catalysts would depend on their ability to oxidize toluene and benzene. K-MnO₂ showed superior properties, i.e. specific surface area, highly low-valent Mn species, high lattice oxygen content, and abundant oxygen vacancy, and then exhibited superior performance during long-term operation (90% conversion in 800 min). The present study uncovered the co-conversion mechanism of multiple VOCs and significantly leveraged the catalytic oxidization technology for VOCs removal in practical application.

Research Progress of a Composite Metal Oxide Catalyst for VOC Degradation

Volatile organic compounds (VOCs) are atmospheric pollutants that have been of concern for researchers in recent years because they are toxic, difficult to remove, and widely sourced and easily cause damage to the environment and human body. Most scholars use low-temperature plasma biological treatment, catalytic oxidation, adsorption, condensation, and recovery techniques to treat then effectively. Among them, catalytic oxidation technology has the advantages of a high catalytic efficiency, low energy consumption, high safety factor, high treatment efficiency, and less secondary pollution; it is currently widely used for VOC degradation technology. In this paper, the catalytic oxidation technology for the degradation of multiple types of VOCs as well as the development of a single metal oxide catalyst have been briefly introduced. We also focus on the research progress of composite metal oxide catalysts for the removal of VOCs by comparing and analyzing the metal component ratio, preparation method, and types of precursors and the catalysts' influence on the catalytic performance. In addition, the reason for catalyst deactivation and a correlation between the chemical state of the catalyst and the electron distribution are discussed. Development of a composite metal oxide catalyst for the catalytic oxidation of VOCs has been proposed.

Mn(CeZr)Ox chelation-induced synthesis and its hydrothermal aging characteristics for catalytic abatement of toluene

In this work, Mn(CeZr)O_x was synthesized by using chelation-induced synergistic self-assembly strategy for the combustion of toluene. The physicochemical properties of the synthesized catalysts were characterized by XRD, ICP-MS, SEM, TEM, XPS and N₂ sorption. The Mn(CeZr)O_x catalyst with T₉₀ = 225 °C exhibited improved catalytic performance than the original MnO_x catalyst (T₉₀ = 260 °C) and had significant low-temperature activity. The relationship between catalyst activity and structure was analyzed. By substituting Ce and Zr elements into the hollow microspheres of MnO₂, oxygen vacancies were produced. The main factors affecting the catalytic activity of the catalyst and the reason why it remained high catalytic activity after a long period of hydrothermal treatment were discussed. After hydrothermal aging, the original pore structure of Mn(CeZr)O_x catalyst collapsed and the specific surface area decreased, but the overall crystallinity of the catalyst increased and the content of oxygen species in the lattice increased. The distribution of Mn and oxygen species on the catalyst surface changed significantly after hydrothermal treatment. The appropriate ratio of Mn⁴⁺ to Mn³⁺ and the ratio of lattice oxygen to adsorbed oxygen species are beneficial to the redox reaction cycle.

Zinc(ii) and cadmium(ii) amorphous metal-organic frameworks (aMOFs): study of activation process and high-pressure adsorption of greenhouse gases

Two novel amorphous metal-organic frameworks (aMOFs) with chemical composition {[Zn2(MTA)]·4H2O·3DMF} n (UPJS-13) and {[Cd2(MTA)]·5H2O·4DMF} n (UPJS-14) built from Zn(ii) and Cd(ii) ions and extended tetrahedral tetraazo-tetracarboxylic acid (H4MTA) as a linker were prepared and characterised. Nitrogen adsorption measurements were performed on as-synthesized (AS), ethanol exchanged (EX) and freeze-dried (FD) materials at different activation temperatures of 60, 80, 100, 120, 150 and 200 °C to obtain the best textural properties. The largest surface areas of 830 m2 g-1 for UPJS-13 (FD) and 1057 m2 g-1 for UPJS-14 (FD) were calculated from the nitrogen adsorption isotherms for freeze-dried materials activated at mild activation temperature (80 °C). Subsequently, the prepared compounds were tested as adsorbents of greenhouse gases, carbon dioxide and methane, measured at high pressures. The maximal adsorption capacities were 30.01 wt% CO2 and 4.84 wt% CH4 for UPJS-13 (FD) and 24.56 wt% CO2 and 6.38 wt% CH4 for UPJS-14 (FD) at 20 bar and 30 °C.

Defective Ultrafine MnOx Nanoparticles Confined within a Carbon Matrix for Low-Temperature Oxidation of Volatile Organic Compounds

The development of catalysts for volatile organic compound (VOC) treatment by catalytic oxidation is of great significance to improve the atmospheric environment. Size-effect and oxygen vacancy engineering are effective strategies for designing high-efficiency heterogeneous catalysts. Herein, we explored the in situ carbon-confinement-oxidation method to synthesize ultrafine MnO_x nanoparticles with adequately exposed defects. They exhibited an outstanding catalytic performance with a T₉₀ of 167 °C for acetone oxidation, which is 73 °C lower than that of bulk MnO_x (240 °C). This excellent catalytic activity was primarily ascribed to their high surface area, rich oxygen vacancies, abundant active oxygen species, and good reducibility at low temperatures. Importantly, the synthesized ultrafine MnO_x exhibited impressive stability in long-term, cycling and water-resistance tests. Moreover, the possible mechanism for acetone oxidation over MnO_x-NA was revealed. In this work, we not only prepared a promising material for removing VOCs but also provided a new strategy for the rational design of ultrafine nanoparticles with abundant defects.

The high thermal stabilizing capability of noble metals (Pd and Au) supported by SBA-15 and the impact on CO oxidation

Precious metal nanoparticles (NPs) are attractive for use in the field of catalysis because of their precisely controlled sizes and shapes.

Insights into the Adsorption of VOCs on a Cobalt-Adeninate Metal-Organic Framework (Bio-MOF-11)

With increasingly severe air pollution brought by volatile organic compounds (VOCs), the search for efficient adsorbents toward VOC removal is of great significance. Herein, an adenine-based metal-organic framework, namely, bio-MOF-11 [Co₂(ad)₂(CH₃CO₂)₂·0.3EtOH·0.6H₂O, ad = adeninate], was synthesized via a facile method, and its VOC adsorption was reported for the first time. This novel bio-MOF-11 was investigated by employing four common VOCs (i.e., methanol, acetone, benzene, and toluene) as adsorbates. The saturated adsorption capacity of these targeted VOCs on bio-MOF-11 was estimated to be 0.73-3.57 mmol/g, following the order: toluene < benzene < acetone < methanol. Furthermore, with the adsorption temperature increasing from 288 to 308 K, the saturated adsorption capacity was reduced by 7.3-35.6%. It is worth noting that acetone adsorption is most sensitive to temperature ascribed to its low boiling point and strong polar nature. Meanwhile, owing to the molecular sieve effect, the adsorption capacity appears negatively correlated to the size of VOC molecules. Besides, the abundant exposed nitrogen atoms and amino groups in bio-MOF-11 cavities facilitate the adsorption of polar VOC molecules. This work promotes the fundamental understanding and practical application of bio-MOF for adsorptive removal of VOCs.

Enhancement of ionizing radiation-induced catalytic degradation of antibiotics using Fe/C nanomaterials derived from Fe-based MOFs

In present work, we studied a novel Fe/C nanomaterial fabricated using Fe-based metal organic frameworks (MOFs) as precursors through thermal pyrolysis to catalyze gamma irradiation-induced degradation of antibiotics, cephalosporin C (CEP-C) and sulfamethazine (SMT) in aqueous solution. The MOFs-derived Fe/C nanomaterials (DMOFs) had the regular octahedrons structure of MOFs and contained element C, Fe and O, while Fe° with a fraction of Fe₃O₄ and Fe₂O₃ were identified. Results showed that DMOFs addition could accelerate the generation of OH during gamma irradiation, while the intermediates of bonds cleavages of antibiotic molecules and OH addition were identified. DMOFs were more effective to improve the decomposition of antibiotic having the higher adsorption capacity like SMT. The degradation rate of CEP-C and SMT increased by 1.3 times and 1.8 times, and TOC reduction at 1.0 kGy reached 42 % and 51 %, respectively by gamma/DMOFs treatment, while only 20.2 % (CEP-C) and 4.5 % (SMT) of TOC reduction were obtained by γ-irradiation alone. The crystal structure, functional groups and magnetism of DMOFs changed slightly after gamma irradiation, which made it possible to be reused. DMOFs were promising to enhance the degradation of antibiotics during gamma irradiation.

A redox-active covalent organic framework for the efficient detection and removal of hydrazine

The removal and detection of soluble hydrazine is of importance due to its harm to soil and subterranean water, but challenging. Herein, we preferentially disposed a porous and redox active covalent-organic framework (DAAQ-TFP COF, denoted as DQ-COF) to simultaneously removal and detect hydrazine. Electroactive sites (anthraquinone units) can be intelligently incorporated into the channel walls/pores of COF. DQ-COF has high crystallinity and good thermal stability, and DQ-COF dropped onto nickel matrix (DQ-COF/Ni composite) still retains high surface area, characterized by PXRD, FT-IR, nitrogen adsorption and TGA. Subsequently, a detailed study of DQ-COF towards hydrazine uptake and detection potentials is explored. DQ-COF as adsorbent unfolds strong removal ability towards hydrazine, the maximum removal capacity of which is up to 1108 mg g^-1, following Friedrich and pseudo-second-order kinetic models. Meanwhile, the DQ-COF supported on nickel renders attractive electrochemical properties, which is efficiently responsive to hydrazine at a part per billion (ppb) level, coupled with a wide linear range (0.5 ˜ 1223 μM), low detection limit (0.07 μM) and high anti-interference ability. There is no other COFs with such a favorable capability in synchronous removal and selective detection towards hydrazine, probably applying in superintending water quality and disposing wastewater.

Taming NO oxidation efficiency by γ-MnO2 morphology regulation

Nitric oxide (NO) emitted from the combustion of fossil fuels has drawn global concern, and the oxidation of NO contributes greatly to the DeNO_x process.

Amorphous-to-crystalline transition and photoluminescence switching in guest-absorbing metal–organic network thin films

Amorphous-to-crystalline (aMOF-to-MOF) transition and simultaneous quenching of luminescence are seen upon water absorption for Nd-terephthalate thin films grown using ALD/MLD method.

Mn-Doped material synthesized from red mud and rice husk ash as a highly active catalyst for the oxidation of carbon monoxide and p-xylene

Red muad and rice husk ash were treated without neutralization by acid to produce a support material (RR).

Tuning effect of amorphous Fe2O3 on Mn3O4 for efficient atom-economic synthesis of imines at low temperature: improving [O] transfer cycle of Mn3+/Mn2+ in Mn3O4

A novel Fe₂O₃ modified Mn₃O₄ catalyst (Fe₅Mn₅-100) has been prepared by adopting a simple co-precipitation method following low temperature baking. Fe₅Mn₅-100 showed exceptionally high catalytic activity for the production of imine.

Mesoporous Cu-Ce-Ox Solid Solutions from Spray Pyrolysis for Superior Low-Temperature CO Oxidation

Development of Pt group metal-free catalysts for low-temperature CO oxidation remains critical. In this work, active and stable mesoporous Cu-Ce-O_x solid solutions are prepared by using spray pyrolysis. The specific surface areas and pore volumes reach as high as 170 m²  g^-1 and 0.24 cm³  g^-1 , respectively. The results of CO oxidation study suggest that (1) the catalyst obtained by spray pyrolysis possesses much higher activity than those made by co-precipitation, sol-gel, and hydrothermal methods; (2) the optimal Cu_0.2 -Ce_0.8 -O_x solid solution presents a reactivity over 28 times that of both single-component CuO and CeO₂ at 70 °C. Based on the study of pure-phase Cu-Ce-O_x solid solutions by selective leaching of segregated CuO_x species, the active center for CO oxidation is confirmed as the bimetallic Cu-Ce-O site, whereas the individual CuO_x particles not only act as spectators but also block the active Cu-Ce-O sites. A low apparent activation energy of approximately 48 kJ mol^-1 is detected for CO oxidation at the Cu-Ce-O site, making Cu-Ce-O_x solid solutions able to present high activity at low temperature. Furthermore, the Cu-Ce-O_x catalysts exhibit excellent stability and thermal tolerance toward CO oxidation.

Adsorption/desorption kinetics and breakthrough of gaseous toluene for modified microporous-mesoporous UiO-66 metal organic framework

In this work, micro-mesoporous UiO-66 was successfully prepared with P123 (EO₂₀PO₇₀EO₂₀) as structure-directing agent by a simple solvothermal method. Adsorption/desorption kinetics of gaseous toluene over pristine UiO-66 and micro-mesoporous UiO-66 were investigated by breakthrough experiments, toluene vapor adsorption isotherm measurements and temperature programmed desorption (TPD) experiments. The interactions between toluene and UiO-66 samples were assessed through the Henry's law constant (K_H) and the isosteric adsorption heat (ΔH_ads). The micro-mesoporous UiO-66 crystal demonstrated 2.6 times toluene adsorption capacity of the pristine UiO-66 when the P123/Zr⁴⁺ molar ratio was 0.2. Results showed that micropore adsorption was the main adsorption process and the larger pores in micro-mesoporous UiO-66 increased molecular diffusion rate and reduced the mass transfer resistance. This result indicated that micro-mesoporous structures and defect sites had a positive effect on toluene molecules capture. The breakthrough times and the working capacities decreased with the increase of the relative humidity and adsorption temperature. A good thermal stability and reproducibility were revealed over the micro-mesoporous UiO-66 in this paper.

Enhanced adsorption performance of gaseous toluene on defective UiO-66 metal organic framework: Equilibrium and kinetic studies

In this study, defective UiO-66 materials modified with Cetyltrimethylammonium bromide (CTAB) surfactant were successfully synthesized by a simple approach. Adsorption and desorption performance as well as the corresponding kinetics of toluene vapor for UiO-66 and the modified materials were intensively studied. The physical and chemical properties of the sample were obtained by a series of characterization techniques. As indicated by the experiments, the number of missing-linker defect sites in UiO-66 were influenced by the CTAB concentration. The presence of the defect sites was served as the main active adsorption sites for efficient toluene vapor adsorption. In result, adsorptive capacity of toluene over CTAB-U-0.5 was improved to 275 mg g^-1, which was much higher than that of UiO-66 (151 mg g^-1). The effects of adsorption temperature, initial toluene concentration and relative humidity on the adsorption capacity of 1000 ppm toluene on UiO-66 were further explored. Furthermore, as-prepared CTAB-modified UiO-66 materials were used for reprocessing cycles, which showed excellent regeneration performance.

Defective Mn xZr1- xO2 Solid Solution for the Catalytic Oxidation of Toluene: Insights into the Oxygen Vacancy Contribution

Oxygen vacancy is conducive to molecular oxygen adsorption and activation, and it is necessary to estimate its contribution on catalysts, especially the doped system for volatile organic compound (VOC) oxidation. Herein, a series of doped Mn _xZr_{1- x}O₂ catalysts with oxygen vacancy were prepared by partially substituting Zr⁴⁺ in a zirconia with low-valent manganese (Mn²⁺). Compared with the corresponding mechanically mixed samples (MB-x) without oxygen vacancy, Mn _xZr_{1- x}O₂ catalysts exhibited better toluene conversion and specific reaction rate, where the differential values were calculated to estimate the contribution of oxygen vacancy on catalytic performance. The increase in oxygen vacancy concentrations in Mn _xZr_{1- x}O₂ catalysts can boost the differential values, implying the enhancement of oxygen vacancy contribution. Density functional theory (DFT) calculations further confirmed the contribution of oxygen vacancy, and molecular oxygen is strongly absorbed and activated on a defective Mn-doped c-ZrO₂ (111) surface with oxygen vacancy rather than a perfect m-ZrO₂ (-111) surface or a perfect Mn-doped c-ZrO₂ (111) surface, thus resulting in the significant improvement in catalytic activity for toluene oxidation. In situ DRIFTS spectra revealed that the oxygen vacancy can alter the toluene degradation pathway and accelerate the intermediates to convert into CO₂ and H₂O, thus leading to a low activation energy and high specific reaction rate.

Aerobic oxidation of fluorene to fluorenone over Co–Cu bimetal oxides

Aerobic oxidation of fluorene to fluorenone was achieved over Co–Cu bimetal oxides using O₂ as an oxidant in the absence of a radical initiator. Co–Cu bimetal oxides showed better catalytic performance than CuO and Co₃O₄.

A comparison study between V-SBA-15 and V-KIT-6 catalysts for selective oxidation of diphenylmethane

Vanadium incorporated mesoporous SBA-15 and KIT-6 catalysts were prepared by a direct hydrothermal method under mild acidic reaction conditions.

Cerium-based UiO-66 metal–organic frameworks explored as efficient redox catalysts: titanium incorporation and generation of abundant oxygen vacancies

For the first time, UiO-66(Ce) was endowed with greatly improved redox photocatalytic activity via Ti incorporation, based on the formation of oxygen vacancies.

Nanoporous 2D semiconductors encapsulated by quantum-sized graphitic carbon nitride: tuning directional photoinduced charge transfer via nano-architecture modulation

A reversed charge transfer pathway in photoredox catalysis has been achieved by rational structure engineering through electrostatically integrating g-C₃N₄ quantum dots with nanoporous CdS nanosheets.

Enhanced hydrophobic UiO-66 (University of Oslo 66) metal-organic framework with high capacity and selectivity for toluene capture from high humid air

Metal organic frameworks (MOFs) are good absorbents that provide high specific surface area, modified pore surface and controllable pore size. The aim of this work is to prepare a MOFs material with good toluene adsorption property in the presence of water. In this paper, modified UiO-66 (University of Oslo 66) was successfully synthesized with polyvinylpyrrolidone (PVP) as structure-directing agent by a simple solvothermal method. The physical and chemical properties were obtained by a series of characterization instruments. Some missing-linker defect sites were observed on modified materials (defective UiO-66) and were known as the main active sites for toluene adsorption. The defective UiO-66 (PVP-U-0.5, 259 mg g^-1) demonstrated 1.7 times toluene adsorption capacity of the pristine UiO-66 (151 mg g^-1) when the PVP/Zr⁴⁺ ratio was 0.5. The interactions between toluene and UiO-66 and PVP-U-0.5 were assessed through the Henry's law constant (K_H) and the isosteric adsorption heat (ΔH_ads), which indicated that stronger interaction between PVP-U-0.5 and toluene molecules. Moreover, PVP-U-0.5 displayed good adsorption capacity (84 mg g^-1) at high relative humidity (70% RH). Water temperature programmed desorption experiments revealed that PVP-U-0.5 had more hydrophobic property, which provided a further possibility for practical application for the removal of toluene.

Highly Advanced Degradation of Thiamethoxam by Synergistic Chemisorption-Catalysis Strategy Using MIL(Fe)/Fe-SPC Composites with Ultrasonic Irradiation

MIL(Fe)/Fe-doped nanospongy porous biocarbon (Fe-SPC) composite was fabricated from MIL-100(Fe) via in situ growth on a unique Fe-doped nanospongy porous biocarbon (Fe-SPC) and was used as Fenton-like catalyst for advanced degradation of thiamethoxam (THIA). Fe was loaded on silkworm excrement and calcined to Fe-SPC with nanospongy and high sp² C structure. The in situ growth strategy embedded the Fe-SPC into MIL-100(Fe) crystals and formed conductive heterojunctions with an intensified interface by Fe-bridging effect, which was confirmed by negative shift of Fe³⁺ binding energy in X-ray photoelectron spectroscopy. MIL(Fe)/Fe-SPC composites exhibited high degree of crystallinity and surface area (Brunauer-Emmett-Teller: 1730 m²/g). Liquid chromatography-mass spectrometry and density functional theory simulations demonstrated that THIA was converted to a relatively stable compound (C₄H₅N₂SCl), which could be captured by MIL-100(Fe) with strong chemical bonding energy (Fe-N, -587 kJ/mol), followed by a significant geometric distortion, resulting in a thorough degradation. Efficient charge separation and synergistic chemisorption-catalysis strategy resulted in the high catalytic activity of MIL(Fe)/Fe-SPC. The composite catalyst concurrently exhibited high mineralization ratio with 95.4% total organic carbon removal (at 25 °C and 180 min) and good recycling ability under wider neutral/alkaline conditions. Endorsing to these intriguing properties, MIL(Fe)/Fe-SPC can be deemed an efficient contender for removal of hard-degradable pesticides and other environmental pollutants in practical applications.

Magnetic ion exchange resin for effective removal of perfluorooctanoate from water: study of a response surface methodology and adsorption performances

This research exhibited the use of magnetic ion exchange (MIEX) resin as an effective adsorbent for the removal of perfluorooctanoate (PFOA) in aqueous solution. The adsorption performance of PFOA was investigated by a batch experiment. All kinds of factors affecting the adsorption of PFOA, including adsorbent dosage, initial concentration, adsorption time, temperature, stirring intensity, coexistent anions, initial solution pH, natural organic matter, ion strength, and bed volume were studied. Moreover, the response surface methodology was put into use to know the key parameters affecting PFOA removal efficiency. The sorption equilibrium and kinetic data could conform well to the Langmuir and pseudo-second-order model, respectively. Thermodynamic parameters were obtained, and it was observed that the adsorption of PFOA onto MIEX resin was an endothermic and spontaneous process at the temperatures under investigation. It was summarized that both chemical absorption and physical adsorption were involved in the PFOA sorption onto the MIEX resin. Moreover, the MIEX resin could be effectively regenerated using a saturated sodium chloride solution. A series of batch experiments and characterizations demonstrated that the MIEX resin possessed a strong adsorption ability with the removal efficiency exceeding 90%, allowing a possible practical application in future water treatment.