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To achieve the CO2 emission control as the urgent task of Carbon Peak and Carbon Neutrality, the CO2 desorption experiments were performed with a new tri-solvent MEA-EAE(2-(ethylamino)ethanol)-DEEA(N, N-diethylethanolamine) with five solid acid catalysts: blended catalysts of γ-Al2O3/H-ZSM-5 = 2:1, H-Beta (Hβ), H-mordenite, HND-8, and HND-580 as H2SO4 replacement. A series of sets of experiments were performed in a typical recirculation process by means of both heating directly at 363 K and temperature programming method within 303~358 K to evaluate the key parameters: average desorption rate (ADR), heat duty (HD), and desorption factors (DF). After analyses, the 0.5 + 2 + 2 mol/L MEA-EAE-DEEA with catalyst HND-580 possessed the best CO2 desorption act at relatively low amine regeneration temperatures with minimized HD and the biggest DF among the other catalysts. Comparing with other tri-solvents + catalysts studied, the order of DF was MEA-BEA-DEEA + HND-8 > MEA-EAE-DEEA + HND-580 ≈ MEA-EAE-DEEA + HND-8 > MEA-EAE-AMP + HND-8. This combination has its own advantage of big cyclic capacity and wider operation region of CO2 loading range of lean and rich amine solution (αlean~αrich), which is applicable in an industrial amine scrubbing process of a pilot plant in carbon capture.

Metal sulfides are recognized as potential candidates for the anode materials of lithium ion batteries (LIBs) because of their high theoretical capacity. However, the low reaction kinetics of metal sulfides leads to their poor cycle life and rate performance, which limits their practical application in the field of energy storage. In this work, we synthesized a self-assembled carbon-free vanadium sulfide (V3S4) nanosheet via a facile and efficient method. The unique mesoporous nanostructure of V3S4 can not only accelerate the migration of ions/electrons, but also alleviate the volume expansion during the lithium ion insertion/extraction process. When used as the anode material of LIBs, the carbon-free V3S4 electrode exhibits remarkable electrochemical performance with ultra-high charge capacity (1099.3 mAh g-1 at 0.1 A g-1), superior rate capability (668.8 mAh g-1 at 2 A g-1 and 588.8 mAh g-1 at 5 A g-1) and impressive cycling ability (369.6 mAh g-1 after 200 cycles at 10 A g -1), which is very competitive compared with those of most metal sulfides-based anode materials reported so far. The strategy in this work provides inspiration for the rational design of advanced nanostructured electrode materials for energy storage devices.

Herein, thiourea (TA) was firstly used as the structure-directing agent to simultaneously tune the morphology and surface acidity of CeO2(w/o) synthesized via one-pot hydrothermal treatment, and exhibits better enhancement on its NH3-SCR activity than urea (UA). In addition, CeO2-TA(10) obtained at the suitable TA/Ce molar ratio of 10 presents the superior NH3-SCR activity in a broad temperature window. The introduction of thiourea promotes the formation of cubic CeO2 nanocubes in catalyst, but not the nanoparticles formed in CeO2(w/o) and CeO2-UA(10). Furthermore, the cubic CeO2 nanocubes mainly expose the crystal faces of {100}, which is helpful to the formation of more oxygen vacancies on the surface of CeO2-TA(10). At the same time, the formation of the specific sulfate species (CeOSO4) is also promoted under the influence of thiourea, thus simultaneously tunes the surface acidity of CeO2(w/o) by enhancing the Bronsted acid sites, although its Lewis acid sites are significantly decreased due to the diminution of the BET surface area. Compared with urea, the using of thiourea as the structure-directing agent also adjusts the physical-chemical properties of CeO2(w/o) and promotes its chemisorbed oxygen concentration. The results presented herein give a new thought for the development of state-of-the-art cerium-based catalysts for the NH3-SCR reaction.

A novel and high-efficiency sludge pretreatment method by combination of freezing and calcium hypochlorite (CH) for promoting the anaerobic fermentation performance was reported in this work. Experimental results indicated that a maximum biohydrogen production of 18.18 ± 0.43 mL/g volatile suspended solids (VSS) was realized by freezing (-5 °C) combined with CH (0.12 g/g VSS) pretreatment, which was 1.19, 4.05 and 11.36 times to that from the sole CH, sole freezing and control fermenters, respectively. Mechanism study showed that freezing + CH pretreatment efficiently disintegrated sludge flocs, producing abundant substrates for anaerobic fermentation. Model substances degradation experiment showed that the biochemical processes were all suppressed by freezing + CH method, but the suppressive degrees for hydrogen-consuming processes were greater than hydrogen-producing processes. 16S rRNA analysis revealed that the microbial community in freezing + CH treated reactor was more beneficial to hydrogen generation than that in the control, because the abundance of functional microbes was enriched from 6.81 % to 34.95 % by the co-treatment. Furthermore, sludge dewatering performance, including settleability, dewaterability and filterability, was enhanced by freezing + CH pretreatment.

To reduce the extensive energy penalty of CO₂ desorption process of amine-based CO₂ capture technology, the combination of “coordinative effect” with “heterogeneous catalysis” was adopted into “MEA+BEA+AMP” tri-solvents at special concentrations (0.1–0.5+2+2 mol/L) with solid base catalysts “CaCO₃” and various solid acid catalysts “γ-Al₂O₃, H-ZSM-5, and blended γ-Al₂O₃/H-ZSM-5”. Experiments were performed to evaluate if there were synergetic effects within the optimization of amine blend concentrations and catalyst selections. Reaction schemes were investigated within the tri-solvents to understand the absorption and desorption mechanisms of coordinative effect. CO₂ absorption was performed at 40 °C, and CO₂ desorption was performed at 90 °C. Five tri-solvent compositions with various catalysts were investigated in terms of initial absorption rate (Iₐbₛ), initial desorption rate (Idₑₛ), heat duty (H), and cyclic capacities, which were categorized into absorption–desorption parameters systematically. The results indicated that tri-solvents with catalysts were highly energy-efficient. The optimized tri-blend was 0.3+2+2 mol/L MEA+BEA+AMP, which performed better than the 2+2 mol/L BEA+AMP benchmark on both absorption and desorption. The optimized regeneration performance of tri-blends was 0.3+2+2 mol/L, and its relative heat duty was 32.9% of that of 5 M MEA and 66.5% of that of 2+2 M BEA+AMP. Results manifested that the combination of solid acid–base catalysts with tri-solvents containing “coordinative effects” was a promising solution to further optimize the energy efficiency of CO₂ absorption–desorption within industrial amine-based CO₂ capture processes.

To solve the multiple air pollution problems caused during waste incineration, simultaneous control of chlorinated aromatic pollutants (e.g., chlorobenzenes, chlorophenol, and dioxins) and nitrogen...

Antibiotic drugs have become dominating organic pollutants in water resources, and efficient removal of antibiotic drugs is the priority task to protect the water environment. Cu3P/SnO2 photocatalysts of various Cu3P loadings (10–40 wt% Cu3P) were synthesized using a combination of hydrothermal synthesis and a partial annealing method. Their photocatalytic activity was tested for tetracycline hydrochloride (TC-HCl) degradation under visible light irradiation. Cu3P/SnO2 samples were characterized by X-ray diffraction (XRD), N2-adsorption, ultraviolet-visible diffuse reflectance spectra (UV-vis DRS), scanning electron microscopy (SEM) and electrochemical impedance spectroscopy (EIS). The results showed that the p–n type heterostructure between Cu3P and SnO2 was successfully constructed, and addition of Cu3P to SnO2 could improve its photocatalytic activity at an optimized loading of 30 wt% Cu3P. In photocatalytic degradation studies, removal rates of around 80% were found in 30 minutes of dark reaction and 140 min of photodegradation. The removal rate was superior to that of Cu3P and SnO2 alone under the same experimental conditions. According to trapping experiments and electron spin resonance (ESR) measurements, photogenerated holes (h+) and superoxide radicals ˙O2− were considered as the main oxidation species in the present system. Finally, the reuse experiments showed high stability of Cu3P/SnO2. This study reports Cu3P as a cocatalyst combined with semiconductor SnO2 to form a highly efficient heterogeneous photocatalyst for the degradation of tetracycline hydrochloride for the first time.

Mercury emission is an important issue during chemical looping combustion (CLC) of coal. The aim of this work is to explore the effects of different flue gas components (e.g., HCl, NO, SO

Sulfamethoxazole is a widely—used antibiotic with high water solubility and low biodegradability, which was considered a refractory environmental pollutant. Hence, a series of functionalized hybrids uniting Cu3P with TiN were prepared. The Cu3P/TiN—x composites remarkably removed the sulfamethoxazole in solution compared with Cu3P and TiN alone. All the as—prepared Cu3P/TiN—x hybrids integrated the advantages of strong adsorption and photocatalysis and achieved removal rates above 70% of sulfamethoxazole. Among the composites, the Cu3P/TiN—2 with a 1:1 molar ratio of Cu: Ti reached a 90% removal rate under dark adsorption for 30 min and subsequent photodegradation for 120 min. The enhanced performance of the Cu3P/TiN—x composites is attributed to the introduced flocculent TiN with a large specific surface area and high conductivity that provide more reactive sites and high electron transferability. Meanwhile, the strong corrosion resistance and chemical stability were also beneficial to the improved performance. Cycling experiments further demonstrate the stability and reliability of the composites. In addition, the capture experiments indicated that the superoxide radical (·O2−) and hydroxyl radical (·OH) played a major role in sulfamethoxazole degradation.

In this work, new CO

The slow kinetics of CO

The three-dimensional (3D) nanoreactor of global-local CNTs conductive network coupled with bimetallic MOFs-derived Co@N-C nanopolyhedra (denoted as gl-CNTs/Co@N-C) promotes the electrocatalytic reduction of oxygen owing to the improved mass transfer ability and stability. Here, the 1D/3D gl-CNTs/Co@N-C nanostructures with enhanced electrocatalytic properties were synthesized in one step by the direct thermolysis of Zn/Co-ZIF/MWCNTs precursor. Based on systematical optimization of the composition and structure, gl-CNTs/Co@N-C carbonaceous porous hybrids containing uniform Co nanoparticles (NPs) can not only effectively enable the conductivity but also expose more active sites. Consequently, the optimal gl-CNTs/Co@N-C nanostructure showed a significantly enhanced catalytic activity for the reduction of oxygen, the half-wave potential (E1/2) and diffusion-limited current density are 0.86 V (vs. RHE) and 5.34 mA cm−2, respectively. Moreover, this catalyst also showed long-term durability and methanol tolerance property, further highlighting the structure superiority of a precisely controllable nanoreactor.

Antibiotic drugs have become dominating organic pollutants in water resources, and efficient removal of antibiotic drugs is the priority task to protect the water environment. Cu

The MEA-DEA blended amine solvents have been a hot research topic recently. This study focused on the absorption efficiency tests of 5 mol/L MEA-DEA blended solvents in a batch and semi-batch process, with the aid of solid chemicals CaCO3 and MgCO3. 5.0 mol/L MEA solvent was used as benchmark. The absorption profiles and initial absorption rates were plotted to select the optimized mix ratio. The results indicated that 2+3M MEA-DEA had good performance in absorption with the aid of CaCO3. After comprehensive consideration, the 2+3M MEA-DEA with solid alkaline chemical (CaCO3) in the absorber and blended catalysts (γ-Al2O3/H-ZSM-5 = 2:1) in the desorber was selected as the energy efficient solution (among 1+4, 2+3, 3+2, and 4+1M MEA-DEA) for the pilot plant. It contained 72–75% of the absorption efficiency but only 46.5–50% of the heat duty compared with 5M non-catalytic MEA.

Three solid chemicals, CaCO3, MgCO3, and BaCO3, were tested to accelerate the CO2 absorption with monoethanolamine (MEA) solvents to verify the effect of heterogeneous catalysis. The experiments were conducted in a batch process at 20 ± 0.2 °C and a semi-batch process under room temperature. For the batch process tests, CaCO3, MgCO3, and BaCO3, accelerated the CO2 absorption with MEA solutions at 1, 3, and 5 mol/L, respectively. The overall absorption periods were reduced by around 39.5%, 36.8%, and 36.8% in 3 M solution; and 31.9%, 19.1%, and 26.6% in 5 M solution. For the semi-batch process tests, CaCO3 and MgCO3 accelerated the CO2 absorption with 5 M MEA solutions by 20% and 20%, from 57 s to 45 s to reach equilibrium at loading of 0.0 mol/mol, and 16% and 12% from 75 s to 63–66 s to reach equilibrium at loading of 0.20 mol/mol. These solid chemicals were good candidates of heterogeneous catalysts of CO2–MEA absorption in an amine scrubbing process.

Porous graphitic carbon nitride (g-C3N4) was successfully synthesized by a simple bacterial etching method. Compared with bulk g-C3N4, the specific surface area of the porous g-C3N4 increased from 14.48 to 75.22 m2/g, and its photocatalytic activity was significantly enhanced by a factor of 2.49 for photocatalytic H2 evolution. The enhancement of photocatalytic activity is attributed to the enlarged specific surface area, remarkably narrowed band gap (2.28 eV) and fast electron transportation benefit from the porous structure.

The Paris Agreement and one of its goals, “carbon neutrality,” require intensive studies on CO2 absorption and desorption processes. When searching for ways of reducing the huge energy cost of CO2 desorption in the amine scrubbing process, the combination of blended amine with solid acid catalysts turned out to be a powerful solution in need of further investigation. In this study, the tri-solvent MEA (monoethanolamine) + EAE(2-(ethylamino)ethanol) + AMP(2-amino-2-methyl-1-propanol) was prepared at: 0.2 + 2 + 2, 0.5 + 2 + 2, 0.3 + 1.5 + 2.5 and 0.2 + 1 + 3 mol/L. The heterogeneous catalytic CO2 desorptions were tested with five commercial catalysts: blended γ-Al2O3/H-ZSM-5, H-beta, H-mordenite, HND-8 and HND-580. Desorption experiments were conducted via a recirculation process with direct heating at 363 K or using temperature programming method having a range of 303–363 K. Then, the average CO2 desorption rate, heat duty and desorption factors were studied. After comparison, the order of CO2 desorption performance was found to be HND-8 > HND-580 > H-mordenite > Hβ > blended γ-Al2O3/H-ZSM-5 > no catalyst. Among the other combinations, the 0.2 + 1 + 3 mol/L MEA + EAE + AMP with HND-8 had a minimized heat duty (HD) of 589.3 kJ/mol CO2 and the biggest desorption factor (DF) of 0.0277 × (10−3 mol CO2)3/L2 kJ min. This study provided a kind of tri-solvent with catalysts as an energy-efficient solution for CO2 absorption and desorption in industrial CO2 capture pilot plants.

The Support information of experimental procedures of rainfall tests and Raw data of Fig.2, Fig.3, and Fig.5

Nano-sized hollow-CdS@g-C3N4 core-shell spheres with different g-C3N4 contents were synthesized by a combined ultrasonication and chemisorption method. The materials were characterized by X-ray powder diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), transmission electron microscopy (TEM), X-ray photoelectron spectroscopic (XPS) and UV–vis diffuse reflection spectroscopy (UV–Vis), etc. The photocatalytic hydrogen production activities of these hollow core-shell spheres were evaluated in water under visible light illumination with Na2S and Na2SO3 as sacrificial reagents. Material characterizations showed that g-C3N4 was moderately coated on CdS hollow nano-spheres with intimate contacts. It was found that the g-C3N4 coating could significantly improve the photocatalytic hydrogen production rate of pure hollow CdS nano-spheres and g-C3N4 coating content of 5 wt% produced the highest hydrogen evolution rate. It is proposed that the synergistic effect of CdS core and g-C3N4 shell effectively promotes the charge separation and facilitates the transfer of corrosive holes from CdS to more robust C3N4, and therefore results in enhanced photocatalytic activity and photo-stability.

Heat-duty reduction is the major challenge in CO2 desorption and amine regeneration. The use of a combination of heterogeneous catalytic desorption with improved amine solvents is a novel approach to address this issue. We studied CO2-desorption tests of noncatalytic diethylamine (DEA) solvents as a benchmark and focused on five blended amines (DEA–monoethanolamine, MEA; 4.5:0.5 to 2.5:2.5 M) with three types of catalysts (γ-Al2O3, H-ZSM-5, and 2:1 blended γ-Al2O3–H-ZSM-5) to explore the synergy effects of DEA-based amine blends with solid catalysts. The heat duty and CO2 production of each case scenario were tested for six sets of solutions with initial loading of 0.5 mol of CO2 per mole of amine at 363–378 K and were compared with those of 5 M DEA solvents. The results showed that the three catalyst conditions (blended catalyst, H-ZSM-5, and γ-Al2O3) followed different trends at rich and lean loadings. Finally, both 5 M DEA and 4.5:0.5 M DEA–MEA with blended catalysts exhibited very low heat duties of 1...

Due to the promotional effect on the surface acidity, SO2 had been usually used to improve the selective catalytic reduction of NOx with NH3 (NH3-SCR) over cerium oxide/cerium-based catalyst via gas phase sulfation. However, CS2 and COS, largely existing in the coke oven or/and gasification flue gas, exhibit stronger reducibility and present the unique physicochemical properties in acidity and reduction property compared to SO2. To the best of my knowledge, the reductive CS2 and COS had not been used to increase the NH3-SCR activity of cerium oxide/cerium-based catalyst. Therefore, the influence of CS2 and COS gas phase sulfation pretreatment on the NH3-SCR performance of CeO2(w/o) had been investigated with SO2 as comparison herein. The results indicate that the promotional effect of the sulfur-containing species pretreatment on the NH3-SCR performance over CeO2(w/o) decrease as following: CS2>COS>SO2, which is in accordance with the intensity of their reducibility. Compared with SO2, the pretreatment with CS2 could induce more Ce4+ to reduce to Ce3+ and generate more surface defects due to its stronger reducibility, leading to more oxygen defects and chemisorbed oxygen formed on the surface of CeO2(w/o). And the sulfation treatment could slightly decrease the crystallinity of cubic CeO2. The characterization results also confirm that the pretreatment with CS2 contributes to the formation of more sulfate species, not only enhances the abundance and strength of Bronsted acid sites on the CeO2(w/o) surface, but also helps to the generation of low-temperature Lewis acid sites compared to SO2. All these should be the crucial reasons for the best de-nitration activity over CeO2-CS2-3 in the operating temperature range. We expected that this research could provide a new strategy for designing novel CeO2-based NH3-SCR catalyst.

In this work, a series of highly efficient and noble metal-free Co0.2Cd0.8S/g-C3N4 nanocomposites were synthesized via a facile one-step hydrothermal strategy. The Co0.2Cd0.8S/g-C3N4 composites modified with 10 wt% g-C3N4 (CCNE10) exhibited the highest photocatalytic hydrogen evolution rate, which was 1.85-times as high as that of pure Co0.2Cd0.8S and 7.85-times higher than CdS. Furthermore, the CCNE10 catalyst was very stable in cycling hydrogen production, which is ascribed to the unique g C3N4 modified CdS@CoS structure with fast photogenerated electron transport character.

The solid catalysts, CaCO3 and MgCO3, were adopted to accelerate CO2 absorption with diethanolamine (DEA) solvent. It turned out that these solid alkaline earth metal carbonates can accelerate CO2 absorption, with overall time reduction up to 14–28% for CaCO3, and 11–28% for MgCO3. After comparing CO2 loadings and time resolved amine concentrations, the solid chemicals can enhance the CO2 absorption of DEA and became compatible with the monoethanolamine (MEA) solution at the same CO2 loading without catalysts. The Lewis base can serve as heterogeneous catalysts for the amine scrubbing process and then facilitate CO2 absorption. These results indicated the heterogeneous catalysts can partly cover the shortage of DEA with CO2 absorption, and facilitate the amine scrubbing process with shorter column with ease.

This work presents qualitative experimental validation of nitrosamine mechanism previously proposed by our group which stated that, without nitrogen dioxide (NO 2 ), nitrosamine could form from secondary amine reaction with only nitric oxide (NO), oxygen (O 2 ), sulfur dioxide (SO 2 ) and carbon dioxide (CO 2 ). Experimentally, N-nitrosodiethylamine (NDEA) from diethylamine reaction was confirmed by detection in both liquid and gas phases. If diethylamine could form NDEA with only NO, O 2 , SO 2 and CO 2 , other secondary amines used more commercially (e.g. piperazine (PZ) and its derivatives and diethanolamine) in the capture of CO 2 could potentially form their corresponding nitrosamines under similar conditions.

A computational chemistry approach was used to elucidate and verify the different nitrosamine formation mechanisms and pathways. These included nitrosamine formation under acid or basic environments in the presence of NO, O2, SO2 and CO2 without NO2. The results clearly showed that nitrosamine could be formed without NO2 via 2 different types of mechanisms, namely, addition and elimination forming N–N bond before proton transfer and proton transfer before N–N bond formation, respectively. The essence of these mechanisms identified in this work was that two reaction steps were required to complete both reaction mechanisms with different nitrosating agents. Two steps were both necessary neither of which could be neglected, if the nitrosamine formation reaction was to be completed. Computational simulation performed on the reactant, intermediate, transition state, and product for each set of reactions also validated the proposed mechanisms. Experiment also detected nitrosamine from the reaction of diethylami...

TiO2 and graphitic carbon (GC) composites with hierarchical pore structures were synthesized using Staphylococcus aureus (ATCC6538) as the biotemplate to modify Degussa P25 TiO2 powder. Then, the composites were applied as photocatalysts for Cr6+ reduction under visible light irradiation. X-ray diffraction, Raman spectroscopy, transmission electron microscopy, nitrogen adsorption–desorption analysis, and X-ray photoelectron spectroscopy demonstrated the presence of a GC coating layer and a unique anatase/rutile mixed crystal phase of TiO2 even after heating at 800 °C. The novel TiO2@GC composites, especially the S-P25-800 sample, which possessed abundant hierarchical mesoporous structures, exhibited strong catalytic activities in Cr6+ photoreduction under visible light. This work provides light to overcome the challenge on synthesis of GC modified TiO2 photocatalysts with the highly reactive but heat-labile anatase main crystal phase at high temperature. Furthermore, the present results demonstrated that ...

A simple hydrothermal process was developed to synthesize Co0.5Cd0.5S/g-C3N4 composite photocatalysts. The crystal structure and surface morphology were characterized with XRD and TEM. The chemical state on the material surface, the chemical structure as well as the ultraviolet–visible light response of the photocatalyst were investigated with XPS and UV–vis DRS. The hydrogen production experiments indicated that the Co0.5Cd0.5S catalyst exhibits enhanced efficiency and stability with the addition of g-C3N4, which effectively inhibited the occurrence of photo-corrosion and promoted the separation efficiency of the photogenerated electron–hole pairs. The highest rate of H2 generation from the composite catalyst is up to 6.31 mmol g−1 h−1 under visible light (λ > 400 nm).

The CO2 desorption analyses of several amines were performed to reveal the behaviour of the amine regeneration process. A typical primary amine (MEA) and two other secondary amines (MMEA and DEA) were selected, in preparation for amine solutions under different concentrations, from 1–7 mol/L. The regeneration curves were generated and plotted to describe the process. It was discovered that the specific CO2 loading (mol/mol) that distinguish the amine regeneration curves into different regions were the same for the specific amine, despite different concentrations. These points were defined as “turning points” on regeneration curves. The turning points of MEA, MMEA, and DEA are located at CO2 loadings of 0.40 mol/mol, 0.38 mol/mol, and 0.28 mol/mol, respectively. The carbamate stabilities of the three amines were compared with each other based on the slope of regeneration curves at slow region. The amine regeneration tests compared the relative heat duty at the first 2 h: MMEA > MEA >> DEA, which is the same order as carbamate stability. This article is protected by copyright. All rights reserved