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The opposite electrostatic potential between the oxygen atoms on the carbonate ion and the hydrogen atoms on PVDF makes the potassium carbonate–ethylene glycol deep eutectic solvent suitable for electrode material separation.

Based on an electric potential test, Fe3+ was selected as an intermediate for synergistic salt leaching of valuable metals from spent LFP and NCM cathodes, while keeping PO43− separated in the residue as FePO4.

A novel UiO-66-F4 nanosheet MOFs is reported for piezocatalytic water splitting, realizing a high H2 evolution rate of 178.5 μmol g−1 within 5 h under ultrasonic mechanical vibration (110 W, 40 kHz).

Municipal solid waste (MSW) classification has become a hot topic with the requirement of “zero waste city”; however, incinerators are designed unclassified currently. Therefore, it is difficult to keep around the rated value of evaporation capacity. Herein, we investigated the effects of evaporation capacity on the formation and removal of PCDD/Fs in a full-scale incinerator firstly. The formation of PCDD/Fs at the 110 % evaporation was lower than that of 100 % from the primary superheater to economizer, as high oxygen concentration. After flue gas flowed through the position of activated carbon injection, PCDD/F emissions at the 100 % evaporation were lower than that at the 110 % as the primary air volume at 110 % was 1.21 times that of 100 %. It had no significant effects on the PCDD/F emissions of the stack gas for an increase approximate 10 % of the evaporation capacity. Although the removal efficiencies of PCDD/F congeners varied in the four parts of the air pollution control devices (APCDs), while it was similar for the effects of APCDs on the removal efficiencies of PCDD/Fs between the two operating conditions. For the two different operating conditions, the removal efficiencies of congeners were kept at high levels (96.32–99.81 %) after flue gas flowed through APCDs and the removal efficiencies of the less-chlorinated congeners general were higher than those in the more-chlorinated congeners. And the removal efficiencies of PCDFs were much higher than PCDDs. These findings provide some new option for controlling PCDD/F emissions in a full-scale incinerator under the MSW classification.

Recently, localized surface plasmon resonances (SPRs) of metallic nanoparticles (NPs) have been widely used to construct plasmonic nanohybrids for heterogeneous photocatalysis. For example, the combination of plasmonic Au NPs and TiO2 provides pure TiO2 visible-light activity. The SPR effect induces an electric field and consequently enhances light scattering and absorption, favoring the transfer of photon energy to hot carriers for catalytic reactions. Numerous approaches have been dedicated to the improvement of SPR absorption in photocatalysts. Here, we have designed a core@shell-satellite nanohybrid catalyst whereby an Ag NP core, as a plasmonic resonator featuring unique dual functions of strong scattering and near-field enhancement, is encapsulated by SiO2 and TiO2 layers in sequence, with Au NPs on the outer surface, Ag@SiO2@TiO2-Au, for efficient plasmonic photocatalysis. By varying the size and number of Ag NP cores, the Au SPR can be tailored over the visible and near-infrared spectral region to reabsorb the scattered photons. In the presence of the Ag core, the incident light is efficiently confined in the reaction suspension by undergoing multiple scattering, thus leading to an increase of the optical path to the photocatalysis. Moreover, using numerical analysis and experimental verifications, we demonstrate that the Ag core also induces a strong near-field enhancement at the Au-TiO2 interface via SPR coupling with Au. Consequently, the activity of the TiO2-Au plasmonic photocatalyst is significantly enhanced, resulting in a high H2 production rate under visible light. Thus, the design of a single structural unit with strong scattering and field enhancement, induced by a plasmonic resonator, is a highly effective strategy to boost photocatalytic activity.

Highly dispersed iron nanoclusters on carbon (FeNC@C) hold great promise for wastewater purification in Fenton-like reactions. The microenvironment engineering of central Fe atom is promising to boost the activation capacity of FeNC@C, which is however remains a challenge. This study developed a self-sacrificed templating strategy to S, N-codoped carbon supported Fe nanoclusters (FeNC@SNC) activator and find the key role of sulfur heteroatoms in regulating the electron structure of Fe sites and final activation property. Investigations revealed that the FeNC@SNC composite exhibited unusual bifunctional activity in both peroxymonosulfate (PMS)- and periodate (PI)-based Fenton-like reactions. We also offered insights into the differences between the degradation of organics by the FeNC@SNC/PMS and FeNC@SNC/PI systems. Specifically, under identical conditions, the FeNC@SNC/PMS system delivered a higher oxidation capability and stronger resistance to nontarget matrix constituents, but showed more severe Fe leaching than the FeNC@SNC/PI system. Furthermore, while mediated electron-transfer process was identified as the major route for pollutant decomposition in both systems, the high-valent Fe-oxo species [Fe (IV)] was the auxiliary reactive species found only in the FeNC@SNC/PMS system. Based on these findings, our results provide profound insights into the design of active and durable Fe-based activators toward highly efficient Fenton-like reactions.

CeO

Solid amine adsorbents are among the most promising CO2 adsorption technologies for biogas upgrading due to their high selectivity toward CO2, low energy consumption, and easy regeneration. However, in most cases, these adsorbents undergo severe chemical inactivation due to urea formation when regenerated under a realistic CO2 atmosphere. Herein, we demonstrated a facile and efficient synthesis route, involving the synthesis of nano-Al2O3 support derived from coal fly ash with a CO2 flow as the precipitant and the preparation of polyethylenimine (PEI)-impregnated Al2O3-supported adsorbent. The optimal 55%PEI@2%Al2O3 adsorbent showed a high CO2 uptake of 139 mg·g-1 owing to the superior pore structure of synthesized nano-Al2O3 support and exhibited stable cyclic stability with a mere 0.29% decay per cycle even under the realistic regenerated CO2 atmosphere. The stabilizing mechanism of PEI@nano-Al2O3 adsorbent was systematically demonstrated, namely, the cross-linking reaction between the amidogen of a PEI molecule and nano-Al2O3 support, owing to the abundant Lewis acid sites of nano-Al2O3. This cross-linking process promoted the conversion of primary amines into secondary amines in the PEI molecule and thus significantly enhanced the cyclic stability of PEI@nano-Al2O3 adsorbents by markedly inhibiting the formation of urea compounds. Therefore, this facile and efficient strategy for PEI@nano-Al2O3 adsorbents with anti-urea properties, which can avoid active amine content dilution from PEI chemical modification, is promising for practical biogas upgrading and various CO2 separation processes.

Piezocatalysis provides a promising strategy for directly converting weak mechanical energy into chemical energy. In this work, we report a simple one-step hydrogen reduction route for the simultaneous generation of surface defects and heterojunctions in Sr0.5Ba0.5Nb2O6 nanorods fabricated by a molten salt synthesis method. The as-fabricated Sr0.5Ba0.5Nb2O6/Sr2Nb2O7 nanocomposites with controllable oxygen vacancies exhibited excellent piezocatalytic activity under ultrasonic vibration, with an about 7 times enhancement of the rate constant (k = 0.0395 min-1) for rhodamine B degradation and an about 10 times enhancement of the water-splitting efficiency for hydrogen generation (109.4 μmol g-1 h-1) for the optimized sample (H2 annealed at 500 °C) compared to pristine Sr0.5Ba0.5Nb2O6 nanorods. This work demonstrates the essential role of a well-modulated oxygen vacancy concentration in the piezocatalytic activity and provides an inspiring guide for designing self-generated heterojunction piezocatalysts.

Syngas production from biomass gasification is a promising technology, which is widely used in the chemical industry. Crop straw and red mud are typical agricultural and industrial wastes, respectively, which are cheap and widespread; however, they cause serious environmental pollution due to the open burning of straw and the toxicity and alkalinity of red mud. In the present work, we converted crop straw into syngas by chemical looping gasification using red mud as a sinter-resistant oxygen carrier. The reactivity of red mud, the syngas yields, and the air pollutant emissions under different conditions were systematically investigated through a thermo-gravimetric analyzer and mass spectrometer. Compared with pure Fe2O3, red mud can promote the syngas yields from crop straw gasification owing to the presence of inert Al2O3 and SiO2. Red mud can effectively reduce the emission of air pollutants owing to the presence of alkaline components such as CaO and Na2O. As the Fe2O3/fuel mass ratio increases, the syngas yield increases and the air pollutant emissions simultaneously reduce; whereas the syngas yield and the air pollutant emissions decrease with increasing heating rate. After calcination at high temperature, the structure of red mud remains stable with slight agglomeration, and can be easily regenerated. Therefore, the promising results provide a breakthrough for efficient utilization and disposal of both crop straw and red mud.

Eliminating indoor formaldehyde (HCHO) pollution at room temperature is highly needed to improve the environment while saving energy. Herein, Pd/CeO2 catalysts with different morphologies of the CeO2 support were employed to investigate their performance for HCHO oxidation. The Pd/CeO2 nanocube (Pd/CeO2-C) catalyst exhibited excellent catalytic activity compared to commercial CeO2 and CeO2 nanorods. HCHO can be completely converted into CO2 and H2O over the Pd/CeO2-C (0.64 wt% Pd) catalyst at a weight hourly space velocity of 36 000 mL g−1 h−1 at room temperature. Multiple characterization results confirmed that the strong interfacial interaction between Pd and the CeO2-C support guarantees a high percentage of metallic Pd on the CeO2-C surface and its high dispersion, which is crucial for the oxidation of formaldehyde at low temperature. The in situ diffuse reflectance infrared Fourier transform results indicated that CO, formate and dioxymethylene species are the main intermediates over the Pd/CeO2-C catalyst, and the active O species is responsible for their decomposition and oxidation. This work may promote the practical application of high performance Pd-based catalysts for indoor HCHO purification and related catalytic processes.

Adsorption and photocatalytic oxidation are promising technologies for eliminating antibiotics (e.g. tetracycline) in aquatic environments. However, traditional powdery nanomaterials are limited by drawbacks of difficult separation and lack of synergistic function, which do not conform to the practical demand. Herein, we developed a simple one-step gelation-pyrolysis route to fabricate hydrophilic three-dimensional (3D) porous photocatalytic adsorbent, in which CuO nanoparticles are uniformly and firmly embedded in nitrogen-doped (N-doped) porous carbon frameworks. The obtained N-doped carbon/CuO bulky composites exhibited excellent ability to adsorb tetracycline hydrochloride (TC), which was subsequently photo-oxidized under visible light. Their hydrophilic nature favors the adsorption processes toward TC, with a maximum adsorption capacity reaching 25.03 mg∙g−1. In addition, >94.4% of TC molecules could be photo-degraded in 4 h with good cycling efficiency after three consecutive tests. Finally, a reaction scheme for removal process of TC was proposed. The obtained 3D porous N-doped carbon/CuO nanocomposites show great promise for efficient removal of antibiotics in aqueous solution by synergistically utilizing adsorption and photocatalytic oxidation processes.

As an alternative renewable energy, upgraded biogas by separating CH4 and CO2 can be used to replace natural gas in automobiles and power grids. Adsorption using solid amine adsorbents is a promising technology for CO2 separation, yet the high cost and complex preparation of support materials have seriously hindered its industrial application. In this study, we developed a green and economical method to prepare nano-SiO2 supports and silica-based solid amine adsorbents; i.e., coal fly ash (CFA) derived nano-SiO2 supports, produced using CO2-assisted precipitation technology without adding templates or pore-expanding agents, were impregnated with polyethylenimine (PEI) to synthesize PEI@nano-SiO2 adsorbents for biogas upgrading via adsorbing CO2. The as-synthesized “40%-PEI@SiO2-6%” adsorbent possessed an initial CO2 uptake of 131 mg g−1 under simulated biogas flow, and showed high adsorption selectivity with a CH4 uptake of

In contaminated soil, pristine biochar has poor applicability for immobilizing vanadium (V), which mainly exists as oxyanions in soil. To elucidate the immobilization potential and biotic/abiotic stabilizing mechanisms of a ferrous sulfate (FS)-modified sludge biochar in a V-contaminated soil from a mining area, we investigated the effects of biochar addition on the soil characteristics, growth of alfalfa, leachability, bioavailability, speciation, and fractionation of V, and changes in the microbial community structure and metabolic response. The results showed that the water extractable, acid-soluble (F1), and pentavalent fractions of V in soil decreased by up to 99 %, 95 %, and 55 %, respectively, whereas the reducible and (F2) oxidizable (F3) fractions increased by up to 45 % and 76 %, respectively. After the soil was treated with the FS-modified biochar for 90 d, the V concentration in the roots and shoots of alfalfa (Medicago sativa L.) decreased by up to 81.5 % and 96 %, respectively. The changes in the speciation, fractionation, and efficient immobilization of V in the studied soil were due to the combined effects of the biochar-induced decrease in soil pH, adsorption and precipitation by elevated iron concentrations, reduction and complexation due to an increase in the organic matter content, and microbial reduction by Proteobacteria.

Recycling of spent lithium-ion batteries (LIBs) has drawn considerable attention in recent years, as an economic solution to the resource shortage. Selective ammonia leaching is recognized as an economical and environment-friendly method, yet it is difficult to separate and reuse the valuable metals from the leachate. In this study, we proposed an NH3-(NH4)2CO3-Na2SO3 leaching system to selectively recover the valuable metals from commercial LiNixCoyMn1-x-yO2 (NCM) and spent NCM. For single-stage leaching, 79.1% of the lithium, 86.4% of the cobalt, and 85.3% of the nickel were selectively leached under optimal conditions, and a mere 1.45% of the manganese was dissolved in the solution. The leaching process in the NH3-(NH4)2CO3-Na2SO3 system was consistent with the surface chemical reaction control model. For multistage leaching, almost all metals (98.4% of the lithium, 99.4% of the cobalt, 97.3% of the nickel) could be leached and a high-purity (>99%) MnCO3 product was simultaneously obtained. The introduction of CO32- not only led to the production of MnCO3 with wide application prospects, but also greatly reduced the consumption of the reducing agent. This study is thus beneficial for recycling of the valuable metals and synthesis of the MnCO3 product from the spent LIBs.

In the present work, we report the growth of all-inorganic perovskite nanorings with dual compositional phases of CsPbBr3 and CsPb2Br5 via a facile hot injection process. The self-coiling of CsPbBr3-CsPb2Br5 nanorings is driven by the axial stress generated on the outside surface of the as-synthesized nanobelts, which results from the lattice mismatch during the transformation of CsPbBr3 to CsPb2Br5. The tailored growth of nanorings could be achieved by adjusting the key experimental parameters such as reaction temperature, reaction time and stirring speed during the cooling process. The photoluminescence intensity and quantum yield of nanorings are higher than those of CsPbBr3 nanobelts, accompanied by a narrower full width at half maximum (FWHM), suggesting their high potential for constructing self-assembled optoelectronic nanodevices.

Adsorption and photocatalysis are promising strategies to remove pollutants of dyes and antibiotics from wastewater. In this study, we demonstrate a rapid microwave-assisted hydrothermal route for the assembly of 2D copper-porphyrin Metal-Organic Frameworks (Cu-TCPP MOFs) within 1 h. The resulting 2D Cu-TCPP nanosheets with excellent crystallinity and a large surface area (342.72 m2/g) exhibited outstanding adsorption performance for typical dyes with adsorption capacities of about 185 mg/g for rhodamine B, 625 mg/g for methylene blue, and 290 mg/g for Congo red, respectively, as well as for representative antibiotics with adsorption capacities of about 130 mg/g for oxytocin, 150 mg/g for tetracycline, and 50 mg/g for norfloxacin, respectively. Meanwhile, the as-prepared 2D Cu-TCPP showed good photocatalytic degradation activity of pollutants after adsorption under irradiation by visible light, reaching removal efficiencies of 81.2 and 86.3% toward rhodamine B and norfloxacin, respectively. These results demonstrate the promising potential of 2D Cu-TCPP for use in the removal of contaminants from wastewater.

Current disposal methods of sewage sludge (SS) and its incinerated ash (ISSA) do not allow for the recycling of the phosphorus (P) present. The aim of this study was to fabricate a P compound ferti...

Ferro-, piezo-, and pyroelectric materials are emerging as potential candidates for converting various forms of primary energy from the ambient environment (e.g., sunlight, mechanical, and thermal ...

Developing highly active single-atom catalysts is one of the most significant issues for future renewable energy technologies. Here we present a facile but effective and efficient strategy for synthesizing colloidal Co single-atom catalysts with excellent catalytic activity using a copolymer, poly(isobutylene-alt-maleic anhydride) (ISOBAM-104), as a stabilizing agent. The catalytic activity of the as-prepared colloidal single-atom catalyst for hydrogen generation from hydrolysis of KBH4 in an alkaline solution was as high at about 14 300 mL-H2 min−1 g-Co−1, which was even higher than that of its Pt, Pd or Rh counterpart. Such a high catalytic activity of the colloidal catalyst was attributable to the in situ formed and well-stabilized Co single-atoms whose existence was confirmed by aberration-corrected high-angle annular dark-field scanning transmission electron microscopy. Moreover, quantum chemical calculations reveal that ISOBAM-104 has a higher binding energy with the Co catalyst than with the well-known conventional protective agents, including poly(N-vinyl-2-pyrrolidone), starch, carboxymethylcellulose sodium, polyvinyl alcohol, sodium polyacrylate and polyethylene glycol. In addition, the use of as-prepared Co catalysts resulted in a much lowered barrier for the dissociation reaction of BH4− than in the cases of using Pt, Pd and Rh counterpart catalysts.

Piezocatalysis and piezo-photocatalysis have recently emerged as promising strategies to address energy and environmental issues through harvesting mechanical energy. Herein, we report that electrical conductivity, rather than piezoelectric coefficient, is more decisive in determining piezocatalytic and piezopotential enhanced photocatalytic activities. The high electrical conductivity of Bi0.5Na0.5TiO3 leads to superior piezo-photocatalytic catalytic activity compared to other reported piezocatalysts for water splitting (H2 production of 158 μmol g−1 h−1), Cr(VI) reduction (first-order rate constant of 0.045 min−1), and degradation of organic pollutants (first-order rate constant of 0.061 min−1 for RhB) by introducing sunlight and ultrasonic mechanical vibration with a frequency of 20–80 kHz. Furthermore, the mechanical power, vibration frequency, and particle size of the material are important factors to optimize the piezocatalytic and piezo-photocatalytic performance. This work provides a useful guide to design new piezocatalytic or piezo-photocatalytic materials by synergistically considering the electrical conductivity and piezoelectric coefficient.

The municipal wastewater treatment sector requires sustainable management of sewage sludge to fundamentally contribute to building zero-waste cities. Herein, we propose an integrated material-flow strategy to make full use of sewage sludge by combining its clean transformation with cement manufacture and petrochemical synthesis. Based on the multi-stage thermochemical conversion process which could effectively reduce the emission of carbonaceous pollutants, the organic components in sludge are converted to syngas with tunable H2/CO molar ratios, while the remaining inorganic components are used to prepare eco-friendly cement clinkers. Under the conditions investigated in this study, 8.9 kmol of syngas with a gross H2/CO molar ratio of 1.7 and 1.9 tonnes of cement clinkers with a sludge-ash replacement ratio of 30.9% can be produced from one tonne of dried raw sewage sludge. The proposed strategy allows sewage sludge to be an alternative feedstock, partially replacing natural resources, to produce petrochemicals and cementitious materials, offering a new pathway to cross-sectoral synergy among municipal wastewater treatment, cement manufacture and petrochemical synthesis.

Deep eutectic solvents (DESs), as a green alternative technology, exhibit great potential to recycle valuable elements from spent lithium-ion batteries (LIBs). However, due to the weak reducing power of DESs, raising the temperature and extending the duration of processing are not efficient for screening suitable DESs for the recycling of LIBs. Here, we propose a novel, simple and robust experimental method to identify suitable DESs for recycling spent LIBs. Based on electrochemical principles, the method proposed in this study can be used to quickly determine the reducing power of DESs. As an example, a choline chloride (ChCl) and urea mixture as a DES was found to possess strong reducing power, with a Li and Co extraction efficiency of 95% from spent LIBs obtained at a reduced reaction temperature of 180 °C and reaction time of 12 h. The results are in good agreement with the results from Fukui functions calculations. The kinetic experiments revealed that the Li and Co extraction is controlled by solution and electron diffusion through the DES. Furthermore, a cubic cobalt oxide spinel (Co3O4) was obtained from the loaded DES using H2C2O4 and NaOH in the dilution–precipitation–calcination process. The current strategy demonstrates great potential for rapid and reliable screening of suitable DESs for the effective recycling of spent LIBs.

Hazardous waste incineration fly ash (HFA) is considered a hazardous waste owing to the high associated concentrations of heavy metals and soluble salts. Hence, cost effective methods are urgently needed to properly dispose HFA. In this study, geopolymers were prepared by alkali-activation technology to stabilize and solidify heavy metals in HFA. In addition, the effects of three different aluminosilicates (metakaolin, fly ash, and glass powder) on the heavy metal immobilization efficiency were investigated. Because the soluble salt content of HFA is too high for their direct placement in flexible landfill sites and water washing can lead to heavy metal leaching, water-washing experiments were conducted after alkali-activation treatment to remove soluble salts. The results suggest that the concentrations of heavy metals leached from geopolymers can satisfy the Chinese Standard limits (GB18598-2019) when the addition of aluminosilicates exceeds 20 wt%. More than 77% of Cl

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