Catalytic Degradation Performance Research Articles

Silver-loaded tannic acid modified Ti3C2 catalyst to efficiently catalyze the degradation of dyes

Ag@Ti3C2-TA nanocomposite catalyst was elaborately constructed by a simple and green method with Ti3C2 as the carrier, tannic acid (TA) as the modifier, and silver nitrate as the precious metal precursor. A series of characterizations were used to analyze morphology and microstructure of the resulting catalyst. The degradation behaviors of the catalyst were studied with rhodamine B (RB) and methyl orange (MO) as the model dyes. The result demonstrated that Ag@Ti3C2-TA exhibited efficient catalytic degradation performance toward both RB and MO, and the degradation percentage increased with the growth of TA content in the catalyst. The catalytic degradation process conformed to the quasi-level kinetic model, and catalytic reaction rate constants of Ag@Ti3C2-TA for RB and MO were 0.972 and 1.478 min−1, respectively. The catalytic degradation percentage of Ag@Ti3C2-TA toward RB and MO still remained above 80% even after 10 catalytic cycles, indicating high degradation percentage and considerable catalytic stability.

Novel ternary Cu0-coupled core-shell Fe0/C nanoparticles micro-electrolysis system toward degradation of organic pollutants: Synergistic effects and removal mechanism

A ternary micro-electrolysis system consisting of carbon-coated metallic iron with Cu nanoparticles (Fe0/C@Cu0) was synthesized for the degradation of sulfathiazole (STZ). Fe0/C@Cu0 catalysts exhibited excellent reusability and stability owing to the inner tailored Fe0 with persistent activity. The connection between Fe and Cu elements in the Fe0/C-3@Cu0 catalyst prepared with iron citrate as iron source exhibited a tighter contact than the catalysts prepared with FeSO4·7H2O and iron(II) oxalate as iron sources. Especially, unique core-shell structure of Fe0/C-3@Cu0 catalyst is more conducive to promoting the degradation of STZ. A two-stage reaction with rapidly degradation followed by gradual degradation was revealed. The mechanism of STZ degradation could be explained by the synergistic effects of Fe0/C@Cu0. Carbon layer with remarkable conductivity allowed electrons from Fe0 transferred freely to the Cu0. The electron-rich Cu0 releases electrons, facilitating the degradation of STZ. Furthermore, the high potential difference between cathode (C and Cu0) and anode (Fe0) accelerate the corrosion of Fe0. Importantly, Fe0/C@Cu0 catalysts exhibited excellent catalytic performance for sulfathiazole degradation in landfill leachate effluent. Results presented provide a new strategy for treatment of chemical wastes.

A new two-fold interpenetrating metal-organic framework based on polyoxometalate: Synthesis, structure, efficient hydrogen evolution and dye degradation

A new POMs-based metal–organic framework (POMOF) with interpenetrated 2-fold architecture compound: [(Ni3(bpp)3·(H2O)11(PW9ⅥW3ⅤO40)]·2H2O (1) (bpp = 3, 5′-bis(pyrid-4-yl)pyridine) has been synthesized under hydrothermally method by introducing a pyridyl-containing rigid ligand into polyoxometalate (POMs) system. In compound 1, the Ni ions simultaneously coordinate with N-donor linker bpp and O-donor linker POM to form 3D frameworks with a large stacking channel. and the 3D frameworks further interpenetrate into each other to form a 2-fold POMOFs architecture. Moreover,the as-obtained POMOF with narrow band (2.07eV) facilitates electron transfer and porous structure for mass transfer. Compound 1 had a high photocatalytic degradation activity of RhB dye with a degradation rate of 90%. At the same time, the as-prepared compound produced excellent catalytic activity and high stability for hydrogen evolution reaction (HER), which manifest an overpotential only 74.6 mV for HER (10 mA cm−2) and Tafel slope of 111 mV dec−1 in 1 M KOH. Our research provides that the as-prepared catalyst possesses bifunctional catalytic performance for both HER and dye degradation.

S-Scheme 2D/2D Heterojunction of ZnTiO3 Nanosheets/Bi2WO6 Nanosheets with Enhanced Photoelectrocatalytic Activity for Phenol Wastewater under Visible Light.

The pollution of phenol wastewater is becoming worse. In this paper, a 2D/2D nanosheet-like ZnTiO3/Bi2WO6 S-Scheme heterojunction was synthesized for the first time through a two-step calcination method and a hydrothermal method. In order to improve the separation efficiency of photogenerated carriers, the S-Scheme heterojunction charge-transfer path was designed and constructed, the photoelectrocatalytic effect of the applied electric field was utilized, and the photoelectric coupling catalytic degradation performance was greatly enhanced. When the applied voltage was +0.5 V, the ZnTiO3/Bi2WO6 molar ratio of 1.5:1 had highest degradation rate under visible light: the degradation rate was 93%, and the kinetic rate was 3.6 times higher than that of pure Bi2WO6. Moreover, the stability of the composite photoelectrocatalyst was excellent: the photoelectrocatalytic degradation rate of the photoelectrocatalyst remained above 90% after five cycles. In addition, through electrochemical analysis, XRD, XPS, TEM, radical trapping experiments, and valence band spectroscopy, we found that the S-scheme heterojunction was constructed between the two semiconductors, which effectively retained the redox ability of the two semiconductors. This provides new insights for the construction of a two-component direct S-scheme heterojunction as well as a feasible new solution for the treatment of phenol wastewater pollution.

Multifunctional TiO2 Nanotube-Matrix Composites with Enhanced Photocatalysis and Lithium-Ion Storage Performances.

As a multifunctional material, TiO2 shows excellent performance in catalytic degradation and lithium-ion storage. However, high electron-hole pair recombination, poor conductivity, and low theoretical capacity severely limit the practical application of TiO2. Herein, TiO2 nanotube (TiO2 NT) with a novel double-layer honeycomb structure were prepared by two-step electrochemical anodization. Honeycombed TiO2 NT arrays possess clean top surfaces and a long-range ordering, which greatly facilitates the preparation of high-performance binary and ternary materials. A binary TiO2 nanotube@Au nanoparticle (TiO2 NT@Au NP) composite accompanied by appropriately concentrated and uniformly distributed gold particles was prepared in this work. Interestingly, the TiO2 nanotube@Au nanoparticle (TiO2 NT@Au NP) composites not only showed the excellent catalytic degradation effect of methylene blue, but also demonstrated large lithium-ion storage capacity (310.6 μAh cm-2, 1.6 times of pristine TiO2 NT). Based on the realization of the controllable fabrication of binary TiO2 nanotube@MoS2 nanosheet (TiO2 NT@MoS2 NS) composite, ternary TiO2 nanotube@MoS2 nanosheet@Au nanoparticle (TiO2 NT@MoS2 NS@Au NP) composite with abundant defects and highly ordered structure was also innovatively designed and fabricated. As expected, the TiO2 NT@MoS2 NS@Au NP anode exhibits extremely high initial discharge specific capacity (487.4 μAh cm-2, 2.6 times of pristine TiO2 NT) and excellent capacity retention (81.0%).

A novel iron molybdate photocatalyst with heterojunction-like band gap structure for organic pollutant degradation by activation of persulfate under simulated sunlight irradiation.

Advanced oxidation processes (AOPs) applied to wastewater treatment have become increasingly well developed and the ability of a single technology to remove difficult organic pollutants is limited. One of the main limiting factors is the insufficient variety and quantity of active species generated during the reaction process and catalyst failure. The coupling of the two methods is a practical and effective approach. In this study, different types of semiconductor persulfate (PS) activators, iron molybdate nanoparticles (I-FeMoO4, II-FeMoO4, and III-FeMoO4), were synthesized by simple solvothermal and calcination methods and applied to photo-assisted activation of PS systems. In addition, the relationship between the intrinsic physicochemical and optoelectronic properties of FeMoO4 and the catalytic degradation performance was revealed by a series of characterization tools, and the dominant catalysts were screened. At an unadjusted pH of 4.86, 0.6g L-1 of PS and 0.4g L-1 of I-FeMoO4 could achieve efficient degradation of several difficult organic dye contaminants (rhodamine b (Rh B), methylene blue (MB), malachite green (MG), methyl orange (MO), and tartrazine (TTZ)) and other antibiotic contaminants (sulfamethoxazole (SMX), tetracycline (TC), norfloxacin (NOR), and carbamazepine (CBZ)) within 5-60min. Possible degradation mechanisms in the I-FeMoO4/PS/Light reaction system were suggested by radical trapping experiments and electron paramagnetic resonance (EPR) tests. Recovery tests demonstrated that I-FeMoO4 has good recoverable stability and did not cause secondary pollution. Finally, our study provided a new perspective on the application of coupled wastewater treatment technologies in the practical treatment of organic wastewater.

MoS2 nanoflowers decorated with single Fe atoms catalytically boost the activation properties of peroxymonosulfate

Reductive iron species have been widely used in advanced oxidation technologies (AOPs) and have shown great potential for the catalytic degradation of various organic pollutants. However, preparing reductive iron-based catalysts that can effectively degrade organic pollutants over a wide pH range remains challenging. Herein, we constructed xFe-MoS2 nanoflowers by introducing atomically dispersed Fe into MoS2 nanosheets, which were demonstrated to catalytically boost the activation of PMS toward the Rhodamine B (RhB) degradation. At an initial concentration of 20 mg L−1, the catalyst xFe-MoS2 could complete the fading and removal of RhB in as fast as three minutes. The 4%Fe-MoS2 showed excellent catalytic performance for RhB degradation over a broad pH range (3.0–11.0), with maximal activity at pH 3.0. MoS2 showed a remarkable synergistic effect in improving the adsorption of RhB and Fe2+/Fe3+ cycling on the catalyst surface, which significantly accelerated the removal efficiency of RhB. Sulfate radicals (SO4•−) and superoxide radicals (O2•−) were identified as the predominant active species during the RhB degradation process. Furthermore, the 4%Fe-MoS2 exhibited great stability and sustainable reactivity. This study provides theoretical analysis and practical exploration of the development and utilization of MoS2 decorated with Fe single atoms for removing pollutants by activating PMS.

Preparation of FeSe2-Based Fenton Catalysts Loaded on Chloro-Methyl Styrene-Based Resins and Study of Activated Persulfate Degradation of Tetracycline

Fenton technology has excellent performance in the treatment of hard-to-degrade organics but tends to cause secondary pollution to the environment. Given its excellent adsorption capacity and the availability of mature adsorption modification studies, poly(chloromethyl styrene)-based resin (PS-Cl) has received much attention for the adsorption of heavy metal ions. However, combining the mature Fenton technology with the highly popular PS-Cl through a stable bridge to exploit the advantages of catalytic degradation performance of Fenton-like technology is the main focus of our work. The PS-NH2@FeSe2 catalyst with a core–shell structure was synthesized. The catalytic degradation of tetracycline solution in the presence of PS-NH2@FeSe2 and persulfate achieved a satisfactory effect. The removal efficiency was as high as 85.94% within 2 h, and the degradation rate constant was 0.02352 min−1. The main advantages of the PS-NH2@FeSe2 catalyst were high stability and recyclability. Thus, the catalyst would not cause secondary pollution to the environment and could still achieve a degradation efficiency of nearly 70% for TC after five times of reuse. The possible catalytic degradation pathways and potential removal mechanisms were investigated through free-radical quenching experiments and HPLC-MS detection of intermediates generated through catalytic degradation. Column experiments were conducted to investigate the effect of the catalyst on the actual removal of wastewater, and a simple flow model was developed using Yellow River water to make the integration of theory and practice possible. In conclusion, the new idea constructed with FeSe2-loaded modified resin offers promising prospects in the removal of refractory organic compounds, such as tetracycline.

Uncommonly efficient degradation performance of photocatalytic ozonation towards tetracycline over synthesizing 3-D g-C3N4 nanosheet based on Si-O-Co framework

3D g-C3N4/Co-MCM-48 was successfully prepared by constructing mesoporous Si-O-Co framework as the template for loading g-C3N4 nanosheet. Excellent synergistic effect and stability in photocatalytic ozonation of tetracycline (TET) were observed owe to the ordered and unique catalyst structure. The results indicated that g-C3N4/Co-MCM-48 possessed better catalytic performance for TET degradation and had an apparent advantage compared with bulk g-C3N4. The highly dispersed Co atoms in the framework acted as reaction centers of ozonation and promoted separation of photo-induced carriers, which further improved the synergistic effect and produced abundant reactive oxygen species (ROSs). Meanwhile, the increase of specific surface area provided sufficient active sites for catalysis. The degradation rate of TET by simulated solar light/g-C3N4/Co-MCM-48/O3 was close to 100% within 8 min, and both the kinetic constant and synergy index of TET degradation were 7.8 and 4.9 times as much as that of simulated solar light/g-C3N4/O3. Effects of various initial pH and Co contents on the TET degradation were studied. In addition, g-C3N4/Co-MCM-48 revealed good stability in photocatalytic ozonation process by cycling for four times, and the pathway of TET degradation was also proposed in this study. It was suggested that g-C3N4/Co-MCM-48 was an excellent catalyst for the practical application of photocatalytic ozonation.

Solid state – Green construction of starch- beaded Fe3O4@Ag nanocomposite as superior redox catalyst

In this present work, a novel approach which had been developed for the green synthesis of starch-decorated Fe3O4 @Ag nanocomposite by using one-step grinding method. The magnetic core shell nanocomposite was designed by magnetite (Fe3O4) surrounded by the starch (maize corn), a biopolymer which act as a matrix for argentum (Ag) nanoparticles. This leads to the core shell structure starch – Fe3O4 @Ag nanocomposite (NC). The morphological and physical properties of the prepared nanocomposite was characterized by FE-SEM, HR-TEM, XPS, VSM, XRD, FT-IR and UV-Vis spectroscopic studies. The average particle size of the nanocomposite was found to be 9–11 nm. In addition, the nanocomposite gains a retentivity magnetisation of 25.50 emu/g makes the NC saveable for reusability. The nanocomposite had a greater stability for more than a month was confirmed with the help of UV-DRS and XRD analysis. The main advantage of the catalyst is temperature independent; During the conversion of benzaldehyde to benzoic acid, the product yield was achieved higher at ambient condition. Furthermore, the NC exposes the outstanding catalytic performance for reductive degradation of various carcinogenic water pollutants such as Methylene Blue (MB) and Methyl Red (MR) within 14 min and 18 min respectively. Moreover, it is also capable for reduction of 4-nitrophenol in an efficient manner. Thus, the NC holds a greater activity towards oxidation and reductive degradation reaction.

Fibrous cellulose nanoarchitectonics on N-doped Carbon-based Metal-Free catalytic nanofilter for highly efficient advanced oxidation process

N-doped carbon materials have been considered as promising efficient and environment-friendly catalysts for sulfate radical-based advanced oxidation processes (SR-AOPs). Herein, we first report a facile strategy to prepare nanoporous N-doped carbon nanofilters (NCNFs) using cellulose nanofibers (CNFs) and metal–organic framework (MOF) as the superior metal-free catalytic for SR-AOPs. In this work, CNFs are employed as nanoporous templates and binders to fix ZIF-8 for fabricating ZIF-8@CNF membrane, and the as-prepared membrane was converted into NCNFs by a simple pyrolysis process. To evaluate the catalytic degradation performance of the NCNFs, methylene blue (MB) was chosen as a model contaminant. It is found that the NCNFs demonstrate a remarkable efficiency for MB removal by peroxymonosulfate (PMS) activation, and 96 % of MB (10 mg/L) was degraded in 15 min. The catalytic reaction and process including removal and washing are very simple and easy because the nanoporous N-doped carbons are fixed on CNF-derived networks. Furthermore, the reaction parameters including reaction temperature, pH, and catalyst/PMS dosage are also investigated. In addition, a series of radical quenching experiments reveal that non-radical mechanism is responsible for the degradation of MB. Importantly, the NCNFs membrane showed a good reusability by the annealing process and it can serve as a catalytic filter in practical organic dye remediation application. This present work shows that MOF derived metal-free carbon membranes have a promising avenue as catalysts for organic dye degradation and water remediation.

Improved heterogeneous photo-Fenton-like degradation of ofloxacin through polyvinylpyrrolidone modified CuFeO2 catalyst: Performance, DFT calculation and mechanism

The exploitation of effective modification means to get highly active and stable catalytic materials for heterogeneous photo-Fenton-like (HPF-like) process has been enormously stimulated by the globally increased demands for water purification. Oxygen vacancies (OVs) modulation is regarded as a prevalent strategy to improve the performance of heterogeneous catalysts. Herein, the polyvinylpyrrolidone (PVP) modified CuFeO2 (PVP/CFO) catalysts were prepared to degrade ofloxacin (OFX) target pollutant in HPF-like process. The modification of PVP introduced the rich OVs and more Fe2+ active sites on PVP/CFO surface, while the aggregation of CuFeO2 particles was inhibited by the modification of PVP. The PVP/CFO catalyst with the addition of 4 g PVP in the synthesis (PVP/CFO-4) possessed more superior catalytic performance for OFX degradation than other prepared catalysts in the present work. Additionally, the as-prepared PVP/CFO-4 catalyst possessed good stability for OFX degradation in HPF-like system. The introduced OVs by PVP modification and the generated photoelectron on PVP/CFO by light excitation effectively accelerated in-situ recycling of Cu2+/Cu+ and Fe3+/Fe2+, which was beneficial for •OH/•O2– formation and OFX mineralization. The quenching experiment and EPR spectra revealed that •OH, •O2- and e- were the major active species, and h+ was auxiliary species for OFX degradation. The OFX degradation pathways were proposed by density functional theory calculation and liquid chromatography mass spectrometry. The overall toxicity of intermediates was relieved after HPF-like degradation of OFX based on quantitative structure–activity relationship predictions.

Yolk-shell Co3 O4 @Fe3 O4 /C Nanocomposites as a Heterogeneous Fenton-like Catalyst for Organic Dye Removal.

The yolk-shell Co3 O4 @Fe3 O4 /C nanocomposites with Co3 O4 as the core, Fe3 O4 /C as the shell, and a cavity structure were synthesized by the hard template method. The physical and chemical properties of the composites were characterized by SEM, TEM, XRD, TGA, XPS, BET, and VSM. The specific surface area of yolk-shell Co3 O4 @Fe3 O4 /C nanocomposites is 175.9 m2 g-1 , showing superparamagnetic properties. The yolk-shell Co3 O4 @Fe3 O4 /C nanocomposites were used as heterogeneous Fenton catalysts to activate peroxymonosulfate (PMS) to degrade MB, which showed high catalytic degradation performance. The degradation rate of MB reached 100 % within 30 min under the circumstances of the yolk-shell Co3 O4 @Fe3 O4 /C nanocomposites dosage of 0.1 g L-1 , the PMS dosage of 1.0 g L-1 , the initial MB concentration of 100 mg L-1 , an initial pH of 5.5, and a temperature of 30±2 °C. The enhanced catalytic performance of the yolk-shell Co3 O4 @Fe3 O4 /C nanocomposites can be attributed to the synergistic effect of the two catalytically active materials and the middle cavity. The effects of different operating parameters and co-existing anion species on MB degradation were also investigated. Electron paramagnetic resonance (EPR) analysis and quenching experiments confirmed that the formation of SO4 ⋅- in the yolk-shell Co3 O4 @Fe3 O4 /C/PMS system contributes to MB degradation. In addition, yolk-shell Co3 O4 @Fe3 O4 /C nanocomposites can be easily separated from the pollutant solution under the action of an external magnetic field, and the degradation rate of MB can still reach 98 % after five cycles, indicating that it has good stability and reusability and has broad application prospects in the field of water purification.

Template-directed growth of sustainable carboxymethyl cellulose-based aerogels decorated with ZIF-67 for activation peroxymonosulfate degradation of organic dyes

A novel 3D advanced oxidation catalyst ZIF-67@C-CMC/rGO based on carboxymethyl cellulose (CMC) and reduced graphene oxide (rGO) was successfully synthesized by facile in-situ growth of Zeolitic imidazolate framework-67 (ZIF-67). C-CMC/rGO aerogel crosslinked by poly (methyl vinyl ether-alt-maleic acid)/polyethylene glycol system (PMVEMA/PEG) as the host material was prepared through a template-directed growth model and exhibited outstanding mechanical properties. The sustainable composite was successfully used as an efficient catalyst for activating peroxymonosulfate (PMS) to generate SO4−· and ·OH, then leads to the removal of organic contaminants. As a result, almost 100 % of 10 ppm MB/RhB solution can be degraded within 5 min due to the combination of catalyst aerogel and PMS. What's more, the aerogel showed a wide pH tolerance range from 4 to 9 and maintained up to 93 % of the contaminant removal rate compared to the initial value after four cycles. The ZIF-67@C-CMC/rGO aerogel with high load rate and excellent catalytic degradation performance not only solved the problem of dispersion and recovery of ZIF-67 particles, but also provided a new idea for the compound wastewater purification in sulfate radical-based advanced oxidation processes (SR-AOPs).

CuBi2O4 surface-modified three-dimensional graphene hydrogel adsorption and in situ photocatalytic Fenton synergistic degradation of organic pollutants

A CuBi2O4/rGH composite catalyst was prepared by modifying CuBi2O4 on the surface of a three-dimensional graphene hydrogel (rGH) via a simple water bath method. The large specific surface area and particular surface adsorption properties of rGH were beneficial for adsorbing and enriching pollutant molecules and could then be further degraded by the in situ photocatalytic Fenton synergistic effect with the addition of H2O2. The introduction of graphene not only increases the surface area and improves the adsorption properties but also accelerates the transfer and separation efficiency of the interface photogenerated charge, thereby promoting the photocatalytic Fenton degradation performance. The adsorption performance and catalytic degradation performance of the 20 % CuBi2O4/rGH composite for phenol were 1.4 and 1.3 times higher than those of CuBi2O4, respectively. Meanwhile, the removal efficiency of phenol in the adsorption and in situ photocatalytic Fenton synergistic system was as high as 80 % within 20 min. In addition, the cross-linked network structure of the 3D graphene hydrogel could be better recycled, which has significant potential in practical applications. Quenching and EPR experimental results showed that hydroxyl radicals (·OH) were the most active species in the synergistic degradation process, and the mechanism of CuBi2O4/rGH adsorption and in situ photocatalytic Fenton degradation was proposed.

Porous organic polymers (POPs) for environmental remediation.

Modern global industrialization along with the ever-increasing growth of the population has resulted in continuous enhancement in the discharge and accumulation of various toxic and hazardous chemicals in the environment. These harmful pollutants, including toxic gases, inorganic heavy metal ions, anthropogenic waste, persistent organic pollutants, toxic dyes, pharmaceuticals, volatile organic compounds, etc., are destroying the ecological balance of the environment. Therefore, systematic monitoring and effective remediation of these toxic pollutants either by adsorptive removal or by catalytic degradation are of great significance. From this viewpoint, porous organic polymers (POPs), being two- or three-dimensional polymeric materials, constructed from small organic molecules connected with rigid covalent bonds have come forth as a promising platform toward various leading applications, especially for efficient environmental remediation. Their unique chemical and structural features including high stability, tunable pore functionalization, and large surface area have boosted the transformation of POPs into various macro-physical forms such as thick and thin-film membranes, which led to a new direction in advanced level pollutant removal, separation and catalytic degradation. In this review, our focus is to highlight the recent progress and achievements in the strategic design, synthesis, architectural-engineering and applications of POPs and their composite materials toward environmental remediation. Several strategies to improve the adsorption efficiency and catalytic degradation performance along with the in-depth interaction mechanism of POP-based materials have been systematically summarized. In addition, evolution of POPs from regular powder form application to rapid and more efficient size and chemo-selective, "real-time" applicable membrane-based application has been further highlighted. Finally, we put forward our perspective on the challenges and opportunities of these materials toward real-world implementation and future prospects in next generation remediation technology.

Green and efficient synthesis of hierarchical porous carbon derived from MOF-235 for catalytic degradation of thiocyanate

Thermal-assisted ball milling is a novel method for the green and efficient synthesis of MOF-235. MOF-235-derived porous carbon exhibits excellent catalytic performance in thiocyanate degradation by persulfate activation.

Kaolin-Supported Silver Nanoparticles as an Effective Catalyst for the Removal of Methylene Blue Dye from Aqueous Solutions.

Water contamination by organic dyes has become a reason for severe environmental pollution and has been threatening the aquatic ecosystem. In this study, kaolin-supported silver nanoparticle (Ag-NP) composites were synthesized by a facile two-step adsorption-reduction method through the reduction of silver ions adsorbed onto locally available, inexpensive, and easily pretreated kaolin surfaces by using sodium borohydride (NaBH4) for the catalytic degradation of methylene blue (MB) dye in aqueous solution. The morphology, structure, surface area, and interaction of the synthesized materials were investigated by scanning electron microscopy, X-ray diffraction, Brunauer-Emmett-Teller, and Fourier transform infrared spectroscopy, respectively. Characterization results showed the successful growth of Ag-NPs on the kaolin surface. To understand the catalytic degradation performance of the catalyst, batch experiments were carried out using MB dye as a model dye. The catalytic reduction tests confirmed the importance of Ag-NPs and the high catalytic activities of the synthesized Ag-NPs/kaolin composite toward MB dye reduction. The degradation results indicated that the increased Ag-NP content on the kaolin surface through repeating cycles could effectively enhance the removal of MB dye from an aqueous solution. The kinetic analysis of the MB dye degradation of the catalyst has fitted the pseudo-first-order kinetic model. More than 97% removal efficiency was still present after five reuse cycles, demonstrating exceptional stability and reusability of the composite. In conclusion, the Ag-NPs supported kaolin (Ag-NPs/kaolin) composite was found to be a promising catalyst for the excellent catalytic activity to reduce a model dye MB from the aqueous solution in the presence of NaBH4 with catalytic efficiency higher than 97% and a reduction rate constant, k red, higher than 0.86 min-1.

Mo-Based Heterogeneous Interface and Sulfur Vacancy Synergistic Effect Enhances the Fenton-like Catalytic Performance for Organic Pollutant Degradation.

Heterogeneous Fenton-like reactions (HFLRs) based on the in situ electrochemical generation of hydrogen peroxide (H2O2) are one of the green methods to remediate organic pollutants in wastewater. However, the design of Fenton-like catalysts with specific active sites and high pollutant degradation rate is still challenging. Here, MoS2-MoC and MoS2-Mo2N catalytic cathodes with heterojunctions were successfully prepared, and the mechanism by which hydroxyl radicals and singlet oxygen (1O2) were generated cleanly without adding chemical additives other than oxygen was clarified. The composite catalysts contained more sulfur vacancies, and the catalytic cathode achieved a high paracetamol pollutant degradation efficiency with 0.17 kWh g-1 TOC specific energy consumption. And almost 5 times higher activity was achieved compared to a pure MoS2 catalytic cathode. Experimental studies confirmed that the production of 1O2 was based on the transformation of superoxide radicals by Mo6+, and 1O2 accounted for approximately 66% of the total degradation and enhanced the nonradical behavior in the reaction. This work provides a sustainable strategy for pollutant utilization, which is valuable for solving the difficult problems of HFLRs and developing new environmental remediation technologies.

Construction of Pt@CNTs/SiC Catalytic Membrane for High-Efficiency Removal of Formaldehyde and Dust

Catalytic membranes can achieve the simultaneous purification of particulate matter (PM) and gaseous pollutants, and their performance depends on the design of a catalyst and its combination with a membrane material. Herein, a novel Pt@CNTs/SiC catalytic membrane composed of a Pt@CNTs (carbon nanotubes) membrane layer and a porous SiC support was developed for the simultaneous removal of formaldehyde and PM at room temperature. The CNT membrane layer underwent vertically integrated growth on a porous SiC support, which provided the catalytic membrane with a pore size of 7.4 μm and a high gas permeance of 240.2 m3·m–2·h–1·kPa–1. The loading of Pt particles on CNTs slightly decreased the gas permeance of the catalytic membrane (219.9 m3·m–2·h–1·kPa–1) but endowed the membrane with catalytic formaldehyde degradation performance. The obtained Pt@CNTs/SiC catalytic membrane with a 240 μm thick CNT layer and 0.8% Pt loading exhibited 99.999% filtration efficiency for 300 nm SiO2 (face velocity = 1 m/min) and 72.1% formaldehyde degradation (gas flow = 49 mL/min), implying that the Pt@CNTs/SiC membrane has good application potential in the collaborative removal of various air pollutants.