High Reduction Efficiency Research Articles

Monolithic Catalysts Supported by Emulsion-Templated Porous Polydivinylbenzene for Continuous Reduction of 4-Nitrophenol.

A monolithic catalyst was fabricated through an emulsion-templating method, postpolymerization modification, and in situ loading of active constituents. To achieve a high specific surface area, divinylbenzene (DVB) was solely employed as the monomer, while the porous structure was adjusted with the porogen content and the types of initiators. Then, anchor points were introduced on the pore wall through nitration and amination of the polymeric scaffold. Using a controlled "silver mirror reaction", monolithic catalysts were obtained after loading of silver nanoparticles (Ag NPs), which was verified from morphological and crystallinity characteristics. The catalytic performance of the resultant monolithic catalyst was determined with the model reduction of 4-nitrophenol (4-NP). In static catalysis, the monolithic catalyst was proved to have a reactively high apparent rate constant and a good reusability. Furthermore, a flow reactor was fabricated with the monolithic catalyst, showing a high efficiency and long-term durability for the continuous reduction of 4-NP. This work broadened the adjustment of porous structures and the subsequent application for emulsion-templated monoliths.

Boosting ethylene yield via a synergistic 2D/0D nanostructured VCu layered double hydroxide/TiO2 catalyst in electrochemical CO2 reduction

A VCu LDH/TiO2 nanocomposite showed high catalytic efficiency in CO2 electrochemical reduction, achieving superior faradaic efficiency for ethylene production, highlighting potential for scalable CO2-to-energy conversion processes.

Development of an eco-friendly mobile plant for car wash wastewater recovery

The global increase in the number of vehicles has a negative impact on the sustainable development due to the increased energy consumption, noise, and air pollution, as well as the increased water consumption used for car wash. The car wash is one of the main after-sale services in the automobile sector. If car wash wastewater (CWW) could be reused, fresh water customarily used in car washing could be preserved. To achieve this goal, it is necessary to implement ?on-site? wastewater treatment systems (i.e. at car wash stations). In this research, a novel pilot plant is developed for ?on site? treatment of CWW. This pilot plant presents combined methods. It consists of three innovative modules: a multipurpose reactor (for coagulation/flotation, aeration/oxidation), deep bed filter (for filtration), and a two-stage bed coalescer (for coalescence filtration). In all these units packing materials are very light (expanded polystyrene (EPS) and polyurethane (PU)) and therefore energy consumption is significantly low. The pilot plant has a simple and light construction, so that it can be easily moved. It has shown very high COD reduction efficiency as well as removal efficiencies of suspended solids, and oil/grease, thus exhibiting high potentials for water recovery at car wash stations.

The construction of an alkynyl-containing porous polymer for enhanced photocatalytic H2O2 generation

The construction of a porous organic polymer with an acetylene active site for simultaneous double-ended hydrogen peroxide production with high oxygen reduction efficiency.

Visualization of the Two-Phase Flow Behavior Involved in Enhanced Dense Phase Carbon Dioxide Pasteurization by Means of High-Speed Imaging

This research explores the two-phase flow behavior involved in enhanced dense phase carbon dioxide inactivation of E. coli DH5α, which has been shown to possess a high microbial reduction efficiency of up to 3.7 ± 0.4 log. We present an experiment in which the liquid sample was pressurized with liquid carbon dioxide to 8.2 MPa and, after saturation, was forced to flow through a mini tube. An experimental setup was developed to visualize the flow patterns (plug, slug and churn flows) occurring in the mini tube by means of high-speed imaging. The values of the wall shear stress were estimated within the mini tube with the help of the gas slug velocities (8–9 m/s) and were compared with threshold shear stress values reported for the disruption of fresh E. coli cells. The results suggest that the preliminary pressurization phase may cause a substantial destabilization of the cell wall of E. coli DH5α.

Density Functional Theory Study of CuAg Bimetal Electrocatalyst for CO2RR to Produce CH3OH

Converting superfluous CO2 into value-added chemicals is regarded as a practical approach for alleviating the global warming problem. Powered by renewable electricity, CO2 reduction reactions (CO2RR) have attracted intense interest owing to their favorable efficiency. Metal catalysts exhibit high catalytic efficiency for CO2 reduction. However, the reaction mechanisms have yet to be investigated. In this study, CO2RR to CH3OH catalyzed by CuAg bimetal is theoretically investigated. The configurations and stability of the catalysts and the reaction pathway are studied. The results unveil the mechanisms of the catalysis process and prove the feasibility of CuAg clusters as efficient CO2RR catalysts, serving as guidance for further experimental exploration. This study provides guidance and a reference for future work in the design of mixed-metal catalysts with high CO2RR performance.

Synergistic Optimization of Morphology and Vacancies on Diatomic Rhodium Catalysts Dispersed on Carbon Nitride for Efficient Photocatalytic Reduction of CO2

AbstractDiatomic site catalysts (DAC) have better performance with higher metal content and more flexible active sites compared with single atomic site catalysts (SAC). Herein, the authors for the first time achieved Rh2 DAC on loose porous g‐C3N4 hollow nanospheres with N‐vacancies and applied to photocatalytic CO2 reduction reaction, overcoming the current limitations of the low electron–hole recombination rate and prolong the lifetime of the photogenerated carrier. The high specific surface area of hollow nanosphere facilitates the uniform dispersion and anchoring of Rh2 diatomic pairs, while the N‐vacancies induce a stable 3N/Rh‐Rh/1N2C coordination between the carrier and Rh2 diatomic pairs. The local charges on the support framework with N vacancies tend to be transferred to Rh2 diatomic site by 3N/Rh‐Rh/1N2C bridge, which made the charge enriched Rh2 diatomic site become the active center of reaction, enhance charge separation efficiency of Rh2/HCNS‐Nv. Compared with Rh1 SAC, further Density Functional Theory (DFT) calculation confirms that Rh2 DAC can effectively stabilize rate‐limiting intermediates CHO*, and well weaken the C─O bond strength in CH3O* species, promote the generation and separation of CH4, resulting in high CO2 reduction efficiency and CH4 electron selectivity of up to 91.65%.

Environmental Performance of the Stormpav Permeable Pavement Using the Stormwater Management Model (SWMM)

Urban stormwater runoff is contaminated with a variety of pollutants, including total suspended solids (TSS) and total phosphorus (TP), as a result of non-source pollution from transportation, residences, and businesses, as well as sediment from human activities and construction sites. These pollutants are expected to degrade the water quality in local rivers and streams, impairing the quality of marine life and contaminating drinking water supplies. This study evaluates the environmental performance of a permeable pavement system in an urban catchment using the stormwater management model (SWMM). Two pavement systems with different hydraulic designs were compared to reduce runoff, increment of groundwater storage and the environmental parameters assessments on total suspended solids (TSS) and Total Phosphorus (TP). The first system comprises a StormPav, which is the UNIMAS innovated green pavement with subsurface hollow cylindrical micro-detention pond storage of about 70% void content. The second system consists of porous concrete (PC) pavement assembled in a layered of coarse and fine particles to ensure water can infiltrate through, with about 40% void content. The environmental impact assessment was applied at Padungan Commercial Centre in the Kuching City of Malaysia. The case study simulated in low impact development (LID) sub-catchment in SWMM to obtain the runoff, infiltration and environmental quality performance. In the assessment, it was found that, for both pavement systems, higher stormsat shorter duration resulted in higher reduction efficiency. The StormPav is more effective in reducing runoff, while presenting a lower value for environmental assessments in removing TSS and TP compared to PC.

Selective CO2‐to‐Syngas Conversion Enabled by Bimetallic Gold/Zinc Sites in Partially Reduced Gold/Zinc Oxide Arrays

AbstractElectrocatalytic CO2‐to‐syngas (gaseous mixture of CO and H2) is a promising way to curb excessive CO2 emission and the greenhouse gas effect. Herein, we present a bimetallic AuZn@ZnO (AuZn/ZnO) catalyst with high efficiency and durability for the electrocatalytic reduction of CO2 and H2O, which enables a high Faradaic efficiency of 66.4 % for CO and 26.5 % for H2 and 3 h stability of CO2‐to‐syngas at −0.9 V vs. the reversible hydrogen electrode (RHE). The CO/H2 ratios show a wide range from 0.25 to 2.50 over a narrow potential window (−0.7 V to −1.1 V vs. RHE). In situ attenuated total reflection surface‐enhanced infrared absorption spectroscopy combined with density functional theory calculations reveals that the bimetallic synergistic effect between Au and Zn sites lowers the activation energy barrier of CO2 molecules and facilitates electronic transfer, further highlighting the potential to control CO/H2 ratios for efficient syngas production using the coexisting Au sites and Zn sites.

Selective CO2 -to-Syngas Conversion Enabled by Bimetallic Gold/Zinc Sites in Partially Reduced Gold/Zinc Oxide Arrays.

Electrocatalytic CO2 -to-syngas (gaseous mixture of CO and H2 ) is a promising way to curb excessive CO2 emission and the greenhouse gas effect. Herein, we present a bimetallic AuZn@ZnO (AuZn/ZnO) catalyst with high efficiency and durability for the electrocatalytic reduction of CO2 and H2 O, which enables a high Faradaic efficiency of 66.4 % for CO and 26.5 % for H2 and 3 h stability of CO2 -to-syngas at -0.9 V vs. the reversible hydrogen electrode (RHE). The CO/H2 ratios show a wide range from 0.25 to 2.50 over a narrow potential window (-0.7 V to -1.1 V vs. RHE). In situ attenuated total reflection surface-enhanced infrared absorption spectroscopy combined with density functional theory calculations reveals that the bimetallic synergistic effect between Au and Zn sites lowers the activation energy barrier of CO2 molecules and facilitates electronic transfer, further highlighting the potential to control CO/H2 ratios for efficient syngas production using the coexisting Au sites and Zn sites.

Prodigious catalytic activity towards reduction of 4-hydroxynitrobenzene sodium salt using one-pot synthesized ZnO-Pd nanobolts

4-Hydroxynitrobenzene sodium salt (4-HNBS) is primarily used to manufacture pesticides, p-aminophenol, paracetamol, and dye intermediates. However, it is released into aquatic systems, which can cause severe health issues in humans. Therefore, novel approaches for detoxifying excessive 4-HNBS must be devised using ultralow amounts of cost-effective catalysts with high reduction efficiencies. To that end, an innovative one-pot, sustainable, and cost-effective method was developed in this study to synthesize ZnO–Pd nanobolt catalysts. The nanobolts were characterized using UV–vis spectroscopy, dynamic light scattering analysis, X-ray diffractometry, field-emission scanning electron microscopy, transmission electron microscopy (TEM), and energy-dispersive X-ray spectroscopy (EDS). TEM images indicated that the nanobolts were 13.8–66.6-nm-thick and that they had a 44.5-nm-diameter central hole. The EDS results suggested that the weight percentages of Zn, O, and Pd were 37.12 %, 23.63 %, and 39.24 %, respectively. This is the first report on the catalytic conversion of 4-HNBS into 4-hydroxyaniline sodium salt (4-HAS), whereas previous studies have mainly focused on converting small amounts of 4-hydroxynitrobenzene (4-HNB) into 4-HAS using high catalyst concentrations. Additionally, the reusability of the catalyst was studied to prevent the problems encountered in large-scale remediation. The synthesized nanobolts exhibited outstanding catalytic properties for converting 4-HNBS to 4-HAS. The rate constant k was estimated to be 0.068 min−1 from the linear plot of ln(C/C0) versus the conversion time. Notably, the nanobolts achieved 99 % reduction of 0.125 mM 4-HNBS after only 30 min of incubation.

Uncovering the Dinuclear Mechanism of NO2-Involved NH3-SCR over Supported V2O5/TiO2 Catalysts.

Commercial vanadium oxide catalysts exhibit high efficiency for the selective catalytic reduction (SCR) of NO with NH3, especially in the presence of NO2 (i.e., occurrence of fast NH3-SCR). The high-activity sites and their working principle for the fast NH3-SCR reaction, however, remain elusive. Here, by combining in situ spectroscopy, isotopic labeling experiments, and density functional theory (DFT) calculations, we demonstrate that polymeric vanadyl species act as the main active sites in the fast SCR reaction because the coupling effect of the polymeric structure alters the elementary reaction step and effectively avoids the high energy barrier of the rate-determining step over monomeric vanadyl species. This study unveils the high-activity dinuclear mechanism of the NO2-involved SCR reaction over vanadia-based catalysts and provides a fundamental basis for developing high-efficiency and low V2O5-loading SCR catalysts.

Highly efficient uranium (VI) remove from aqueous solution using nano-TiO2-anchored polymerized dopamine-wrapped magnetic photocatalyst

Radioactive uranium containing wastewater discharged from uranium mining and associated nonferrous metallurgy posing a serious threat to human health and aquatic ecosystem. In this paper, we attempted to use photocatalytic technology to reduction U(VI) from diluted uranium-containing wastewater and recover dispersed uranium by constructing a highly efficient photocatalyst. A polymerized dopamine (PDA)-wrapped magnetic base was introduced to support spherical anchoring of TiO2 nanoparticles, and the newly designed photocatalyst (TiO2/PDA@Fe3O4) with a particle size of 450∼700 nm had a remarkable multilayer-ball structure and displayed remarkably high recyclability and photocatalytic reduction efficiency for aqueous uranium under UV radiation. Uranyl with an initial concentration of 2.0 mg/L, and solution pH of 6.0 was ∼100% removed within 40 min, and no interference by coexisting anionic and cation ions was not observed. In determination of photocatalytic mechanism, the results showed that nanoscale TiO2 particles on TiO2/PDA@Fe3O4 surface can adsorb U(VI) efficiently and reducing them under UV radiation. Furthermore, TiO2/PDA@Fe3O4 nanocomposites displayed high stability performance, the uranium removal efficiency was greater than 83.5% after six times recycle. The proposed engineered interface fabricate strategy has the potential for use in universal hydro-stable micro/nano-particle production and may contribute to more effective uranium extraction from waste liquids.

Graphene Quantum Dots for Photocatalytic CO2 Reduction

Sustainable solar fuels production through reduction of molecular CO2 using photocatalysts is an eco‐friendly and dependable source of energy for the future and for controlling the global warming. The growth of quantum dots, especially, graphene quantum dots (GQD), has emerged as a flat 0D material offering unique properties like enhanced solar light absorption, surface reactivity, charge separation, and migration efficiency, which are invariably systemizing high solar photocatalytic CO2 reduction efficiency. In this review, the insights of thermodynamics and kinetics of CO2 reduction are discussed, followed by detailed encapsulation of modification strategies of GQDs and intrinsic analysis of CO2 reduction utilizing solar light. Progressively, the challenges and futuristic outlook of GQDs‐based photocatalytic systems for solar fuels production is also presented.

Cheap transition metal reinforced donor–acceptor covalent organic frameworks for CO2 photoreduction

Artificial photoreduction of CO2 is considered an attractive solution for simultaneously achieving carbon neutrality goals and solving the energy shortage crisis. In this study, a donor–acceptor (D–A) covalent organic framework (COF), COF-BT, comprising (1,1′-biphenyl)-3,3′,5,5′-tetracarbaldehyde and 4,4′-(2,1,3-benzothiadiazole-4,7-diyl)bis[benzenamine] was prepared, and cheap CoO was introduced into COF-BT via a two-step impregnation-calcination process to obtain Co-COF-BT with immobilized transition metals. Photoelectrochemical experimental and theoretical results indicate that the D–A structure of Co-COF-BT reduces the band gap, enhances visible light absorption, inhibits electron–hole recombination, and prolongs the life of photogenerated carriers. The introduction of CoO provides additional active sites, and the Co-S bond in Co-COF-BT provides an additional channel for ultrafast electron migration from the COF-BT unit to the CoO active center, which increases charge mobility and reduces the energy barrier formed by *COOH intermediates. Thus, the excellent photocatalytic CO2 reduction activity of Co-COF-BT is achieved with a CO yield of 2423 μmol g−1h−1 and selectivity > 99% under visible light. The superior photocatalytic performance is attributed to the synergistic effect of D–A moieties and CoO in Co-COF-BT. This study not only presents a novel COF-based photocatalyst with high charge transfer efficiency and high catalytic activity in CO2 reduction but also provides a potential strategy to fine-tune photoelectronic properties by adjusting the functional building blocks and additional metal active sites.

Assessing the contaminant reduction effects of the COVID-19 pandemic in China

This paper presents a comprehensive system for assessing contaminant emissions, including the dominant contaminant reduction effects, recessive contaminant reduction effects, and contaminant reduction efficiency indexes. The system is used to evaluate the linkage changes in contaminant emissions reduction across different sectors, the ease of regulation, and the returns on emissions reduction efforts. The study's results demonstrate that firstly, COVID-19 initially reduced contaminant emissions across almost all sectors, although this effect waned over time. Secondly, applying conventional regulatory measures to sectors with high reductions in contaminant emissions may not yield the expected results. Thirdly, while some sectors may be more difficult to regulate, they may offer a higher return on investment in terms of emissions reduction. Based on the above results, the paper advocates for timely measures to consolidate environmental gains, prevent rebounding of contaminant emissions, prioritize supervision and management of easily regulated sectors, prioritize upgrading of cleaner production in sectors with high reduction efficiency indices, and increase investment in environmental technology.

Construction of high-capacitance carbonate-rich bimetallic layered (hydr)oxides onto ZIF-67–derived Co/CoO-N-carbon hybrid cubes for high-performance symmetric supercapacitors

Herein, we fabricated carbonate-rich bimetallic layered hydr(oxides) (CoMnOx), which are primarily used as active materials for supercapacitors, using a simple hydrothermal method. CoMnOx was deposited onto cobalt oxide (CoO), which was produced by pyrolyzing ZIF-67 at 800 °C under N2 atmosphere. The Co/CoO cubes synthesized using carbonized ZIF-67 (ZIFC) were covered with CoMnOx shells with high reduction efficiency and abundant Co active sites and surface O species. The effects of the carbonate species present between the CoMnOx layers and at the surface of the hybrid CoMnOx@ZIFC materials were evaluated using PXRD and XPS. The peaks at the binding energies of 290 and 400 eV in the C 1s and N 1s XPS profiles of CoMnOx@ZIFC, respectively, indicate the presence of carbonate species and coordination of CoO and Co with the N-rich carbon materials, respectively. The FE-SEM images of CoMnOx@ZIFC revealed the partial decomposition of the cubic structure of ZIFC, which agreed with previously reported data. Moreover, the elemental composition of CoMnOx@ZIFC was confirmed using EDS mapping and point analysis. The CoMnOx@ZIFC electrodes exhibited a remarkable specific capacitance/capacitor of 963 F g−1/588 C g−1 at 1 A g−1 and excellent cycling stability over 1000 cycles, which was superior to those of previously reported MOF-derived carbonate-based materials in alkaline electrolytes. The CoMnOx@ZIFC||CoMnOx@ZIFC symmetric supercapacitor exhibited an energy density of 60.75 W h kg−1 with a power density of 5947 W kg−1 and an exceptional cycling stability (>99.5 %) after 3000 cycles.

Multiscale Fuzzy Entropy-Based Feature Selection

In practice, it is common that there will be the same decision results under different scale conditions. Therefore, knowledge representation based on a single scale feature framework is far from meeting the needs of practical applications. Based on this, multi-scale data has received extensive attention. Feature selection is an important application of fuzzy multigranularity data analysis model. The existing multi-scale fuzzy granulation-based feature selection methods remove redundant or irrelevant features by selecting the optimal scale. However, this will lose the information corresponding to the remaining scale fuzzy granules, which will affect the classification results or learning tasks. Inspired by this, multi-scale fuzzy entropy is defined to fuse the granule information at different scales, and applied to feature selection. First, the feature with maximum multi-scale fuzzy mutual information is first selected. Then, the most significant features are gradually selected by evaluation metric that simultaneously considers the redundancy, relevance and complementary. A multi-scale fuzzy entropy-based feature selection (MFEFS) algorithm by means of this evaluation index is further designed. Finally, the proposed method is compared with some state-of-the-art methods. The experimental results show that the proposed algorithm has higher reduction efficiency than the comparison algorithms.

Construction of the copper metal-organic framework (MOF)-on-indium MOF Z-scheme heterojunction for efficiently photocatalytic reduction of Cr(VI)

A novel two-dimensional (2D)–on-3D metal–organic framework (MOF) “dimensionality-hybrid” heterostructure was established by the anisotropic growth method and exploited as the robust photocatalyst to efficiently remove Cr(VI) ions in the polluted water system under visible irradiation. The 2D Cu-MOF nanosheet was in situ grown around the 3D In-MOF nanorods, thus forming the MOF-on-MOF Z-scheme heterojunction (denoted as Cu-MOF@In-MOF). Benefiting to the large specific surface area (718.1 m2 g−1) and promoted the photoabsorption property within visible-light region, the attained Cu-MOF@In-MOF heterojunction exhibited the remarkably enhanced separation ability of photocarriers and electron transfer. Comparing with the sole MOFs (Cu-MOF and In-MOF) the 2D/3D Cu-MOF@In-MOF Z-scheme heterojunction demonstrated high photocatalytic reduction efficiency toward Cr(VI) (98%) within 1 h under visible-light irradiation (50 mg/L, pH 5.4), markedly higher than those of the sole MOFs and most of reported photocatalysts (50 mg/L, pH 5.4). Moreover, the photocatalysis mechanism of the Cr(VI) reduction by Cu-MOF@In-MOF was provided based on the analysis of energy band structure trapping experiments and electron spin resonance results. The presented MOF-on-MOF photocatalyst shows the synergistic effect of various components for efficiently photocatalytic removal of harmful pollutants in water, thus giving the great potential applications in environmental governance field.

Schwertmannite-based heterogeneous Fenton for enhancing sludge dewaterability over a wide pH range

Fe-based Fenton technology is commonly used to enhance sludge dewaterability, but it requires subsequent neutralization, resulting in excessive chemical consumption. In this study, we investigated the feasibility of using schwertmannite-composited Fe3O4 (Sch/Fe3O4) as a heterogeneous Fenton catalyst to enhance sludge dewaterability without the need for pH adjustment. A high reduction efficiency of sludge specific resistance to filtration (94.4%), moisture content (11.4%) and bound water (45.5%) after Sch/Fe3O4 +H2O2 treatment at initial pH 7.5 were obtained, suggesting that Sch/Fe3O4 +H2O2 posed good dehydration performance without any acidification. SO42- and H+ generation in Sch/Fe3O4 system played an important role in sludge pH decrease, which facilitated sludge cell lysis, intracellular water release, and provided a suitable pH for Fenton reaction. Reactive species (•OH, •O2-, and 1O2) from Sch/Fe3O4 +H2O2 could effectively destroy sludge EPS, releasing more bound water. Additionally, the negatively charged compounds were neutralized by dissolved Fe2+/Fe3+. Sch/Fe3O4, as a skeleton builder, rearranged the dissociative sludge flocs to improve the incompressibility and permeability of sludge cake. Finally, sludge treated with Sch/Fe3O4 +H2O2 achieved organic matters reserve, heavy metals reduction, further benefiting the final disposal.