Search

Perfluorooctanoic acid (PFOA) has drawn increasing attention as a highly persistent organic pollutant. The inherent stability, rigidity and potential toxicities characteristics make it a challenge to develop efficient technologies to eliminate it from water. Photocatalytic technology, as one advanced method, has been widely used in the degradation of PFOA in water. In this review, recent progress in the design of photocatalysts including doping, defects engineering, heterojunction and surface modification to boost the photocatalytic performance toward PFOA is summarized. The relevant degradation mechanisms were also discussed in detail. Finally, future prospect and challenges are proposed. This review may provide new guidelines for researchers to design much more efficient photocatalysts applied in the elimination of PFOA. [Display omitted] • Photocatalytic degradation of PFOA from water was reviewed. • Multiple strategies for improving degradation efficiency of PFOA were categorized. • The underlying degradation mechanisms of PFOA were summarized. • Future prospect and challenges toward photocatalytic degradation of PFOA from water were proposed. [ABSTRACT FROM AUTHOR]

The piezoelectric polarization electric field induced by the non-centrosymmetric triangular holes of g-C 3 N 4 was beneficial to promote the separation and transport of photogenerated carrier. The porous structure of porous tubular g-C 3 N 4 (PTCN) facilitated the absorption of visible light, and its thin and highly extended cambered tube wall lamellae and large specific surface area per unit cross-sectional area facilitated the response of mechanical vibration, thus improving the piezo-photocatalytic performance. The piezo-photocatalytic degradation rates of tetracycline hydrochloride (TCH), ciprofloxacin (CIP), rhodamine B (RhB) and methylene blue (MB) by PTCN were 89%, 51%, 100% and 100% within 30 min, respectively. The yield of H 2 O 2 reached 196.6 μM within 120 min. Photocurrent intensity, finite element simulation, DFT calculation, PFM and free radical quantification experiments were conducted to explain the reason for the high piezoelectric performance of PTCN, and the reason for the higher piezoelectric properties of the tubular structure than the bulk structure was also analyzed in depth. This work filled the research gap of tubular g-C 3 N 4 in piezo-photocatalysis and made up the research gap of the influence of material morphology structure on piezoelectric properties, which provided a new reference and incentive for future piezoelectric photocatalysis research. [Display omitted] • Porous tubular g-C 3 N 4 was obtained by simple wet precursors calcination. • Thin tube wall improved the piezo-photocatalytic performance of tubular g-C 3 N 4. • DFT calculation and finite element simulation revealed piezoelectric properties of PTCN. • Piezoelectricity enhanced photogenerated carrier separation and radical generation. [ABSTRACT FROM AUTHOR]

Social development is accompanied by technological progress, which commonly leads to the expansion of pollution As an essential resource of modern medical treatment, antibiotics have become a hot topic in the aspect of environmental pollution. In this study, we first used fish scales to synthesize N, P-codoped biochar catalyst (FS-BC) as peroxymonosulfate (PMS) and peroxydisulfate (PDS) activator to degrade tetracycline hydrochloride (TC). At the same time, peanut shell biochar (PS-BC) and coffee ground biochar (CG-BC) were prepared as reference materials. Among them, FS-BC exhibited the best catalytic performance due to the excellent defect structure (I D /I G = 1.225) and the synergism of N, P heteroatoms. PS-BC, FS-BC and CG-BC achieved degradation efficiencies of 86.26%, 99.71% and 84.41% for TC during PMS activation and 56.79%, 93.99% and 49.12% during PDS, respectively. In both FS-BC/PMS and FS-BC/PDS systems, non-free radical pathways involved singlet oxygen (1O 2), surface-bound radicals mechanism and direct electron transfer mechanism. Structural defects, graphitic N and pyridinic N, P–C groups and positively charged sp 2 hybridized C adjacent to graphitic N were all critical active sites. FS-BC has the potential for practical applications and development because of its robust adaptation to pH and anions and stable re-usability. This study not only provides a reference for biochar selection, but also suggests a superior strategy for TC degradation in the environment. [Display omitted] • SynThesis of a novel N, P co-doped fish scale biochar catalyst. • The degradation efficiency of TC can reach 99.71% in FS-BC/PMS system. • Differences in the activation mechanism of FS-BC on PMS and PDS do not appear. • The activation mechanism only involved non-free radical mechanism. [ABSTRACT FROM AUTHOR]

Tetracycline (TCN) is a typical antibiotic with ecological toxicity, which is easy to cause bacterial drug resistance. Single-atom catalysts have a broad application prospect in the remediation of antibiotic polluted water by activated persulfate (PDS), but its catalytic properties are limited because of its high surface energy and easy aggregation. Therefore, in our manuscript, a novel nitrogen doped magnetic graphene oxide confined Fe-Co dual single-atom catalyst (Fe/Co(1:1) (S) -NMGO) was prepared by one-step molten salt assisted high temperature pyrolysis. XPS and AC-HAADF-STEM analysis indicated single-atom Fe and Co existed. Fe and Co atoms were bound to the material mainly through coordination with pyridinic N and pyrrolic N. While single-atom Fe and Co were simultaneously introduced into the modified materials, the removal rate of TCN reached 93.1%, implying the significant synergistic effect of single-atom Fe and Co on TCN removal. Molten salt assisted high-temperature pyrolysis significantly improved the TCN degradation rate. In addition, this research showed that the existence of magnetite nanoparticles was beneficial to improve the separation performance of the single-atom catalysts as well as the catalytic performance. At the same time, the effects of some key parameters (Fe/Co molar ratio, catalyst dosage, PDS dosage, initial pH, coexisting anions and humic acids) on TCN degradation in Fe/Co(1:1) (S) -NMGO/PDS system were also investigated. The catalytic potential in actual water and regeneration performance of the material were also evaluated. The possible activation mechanism and degradation pathway of TCN were proposed. These findings will provide important reference for the future design and application of single-atom-involved catalysts. [Display omitted] • Fe/Co dual single-atom catalyst was prepared by molten salt assisted pyrolysis. • Molten salts could provide a high polarity environment to destroy metal-metal bond. • Single Fe and Co atoms anchored on NMGO are verified by AC-HAADF-STEM. • TCN removal rate in this system could reach 93% at low catalyzer and PDS dosage. • Free radical (SO 4 •− >O 2 •− >HO•) oxidation were the main degradation mechanisms. [ABSTRACT FROM AUTHOR]

The sulfate radical-based advanced oxidation processes (SR-AOPs) are considered to be efficient and environmentally friendly for handling persistent organic pollutants issues. The activation of persulfate (PS) by biochar (BC) materials derived from waste biomass is the current research hotspot in SR-AOPs. Herein, we propose bimetal modified peanut hull-derived biochar (BC-Fe-1-Zn) catalysts to activate PS to degrade tetracycline (TC) with a removal efficiency of 90% in 120 min. The physicochemical properties and reaction mechanisms are well studied through the effective combination of various characterization techniques and experiments. SO 4 •– , •OH and electron transfer are all involved in the degradation of TC and SO 4 •– is the main reactive oxygen species (ROSs). The Fe and Zn oxides and the oxygen-containing functional groups on the catalyst surface are considered as the active sites for the reaction. Moreover, the influences of different factors (such as pH, catalyst dosage, PS dosage and coexisting ions) on the TC remove efficiency are studied. Simultaneously, the TC degradation products and its reasonable degradation paths are analyzed. This work provides new ideas for the rational design of biochar-supported bimetallic catalysts and revealed that using BC-Fe-1-Zn in AOPs technology to environmental remediation is a promising approach. [Display omitted] • Biochar is prepared from peanut hull and applied for activating PDS. • Transition metals Fe and Zn are successfully loaded on biochar to promote electron transfer. • The synthesized catalyst owns large specific surface area, abundant functional groups. • Sulfate radicals and hydroxyl radicals contributed to the degradation of TC. [ABSTRACT FROM AUTHOR]

Abstract It is of great significance to timely, accurately, and effectively monitor land use/cover in city regions for the reasonable development and utilization of urban land resources. The remotely sensed dynamic monitoring of Land use/land cover (LULC) in rapidly developing city regions has increasingly depended on remote-sensing data at high temporal and spatial resolutions. However, due to the influence of revisiting periods and weather, it is difficult to acquire enough time-series images with high quality at both high temporal and spatial resolution from the same sensor. In this paper we used the temporal-spatial fusion model ESTARFM (Enhanced Spatial and Temporal Adaptive Reflectance Fusion Model) to blend Landsat8 and MODIS data and obtain time-series Landsat8 images. Then, land cover information is extracted using an object-based classification method. In this study, the proposed method is validated by a case study of the Changsha City. The results show that the overall accuracy and Kappa coefficient were 94.38% and 0.88, respectively, and the user/producer accuracies of vegetation types were all over 85%. Our approach provides an accurate and efficient technical method for the effective extraction of land use/cover information in the highly heterogeneous regions. [ABSTRACT FROM AUTHOR]

This paper constructs a comprehensive evaluation system of human settlements focusing on housing conditions, urban natural environments, social economy, and public infrastructure. Principal Component Analysis and Cluster Analysis are used to analyze and rank the 2003–2013 human settlements index and create five clusters for 35 major cities in China (including municipalities, provincial capitals, and Prefecture-level cities). On the basis of four years of a spatial analysis of the human settlements index, we find that living conditions of 35 Chinese cities have significantly improved; severe air pollution persists in China, with large differences between the north and the south; weak correlation between urban human settlements and the growth rate of economic development; and the infrastructure of China's mega cities is overloaded. The results confirm and quantify growing geographic disparities and deep structural urban challenges that are associated with rapid economic growth and social change, leaving many cities in China to struggle with worsening pollution, excessive demand on existing infrastructures, and housing prices that rise faster than disposable incomes. [ABSTRACT FROM AUTHOR]

• DMD effectively predicts the state transitions of core dynamics and xenon transients. • The impact of DMD parameters on prediction performance is investigated. • Detailed analysis of the 3-D LWR Core Transient Benchmark is performed. This study proposes a method based on Dynamic Mode Decomposition (DMD) for predicting the state transitions of core dynamics and xenon transients in nuclear reactors. Both types of transients, occurring at different time or spatial scales, have significant impacts on the stability and safety of nuclear reactors. The DMD method is employed to model and predict the transient behaviors in nuclear reactors. DMD is a data-driven model simplification technique that extracts the dynamic modes, i.e., characteristic patterns, from time-series data. By applying DMD to the data of core dynamics and xenon transients, we obtain the characteristic modes of the system under different states, which are then used for predicting state transitions. Simulation experiments are conducted using the benchmark problems of the 3D LWR transient cores provided by NEACRP. The results demonstrate that the DMD-based method effectively predicts the state transitions of core dynamics and xenon transients in nuclear reactors. The accuracy and reliability of the method are validated through the analysis and comparison of predicted results with actual data. Additionally, the impact of model parameters on prediction performance is investigated, and optimization strategies are proposed to further improve the prediction results. The findings of this study offer a novel approach and insights for predicting transient behaviors in the field of nuclear energy. [ABSTRACT FROM AUTHOR]

In this work, a series of perovskite nanocrystals glasses with different concentrations of Tb3+ doped CsPbI 3 , which have excellent characteristics in terms of water resistance and cyclic thermal stability, were prepared by melt quenching and in situ crystallization methods. With the introduction of Tb3+, the photoluminescence quantum yield of CsPbI 3 was greatly improved. Considering that the two fluorescence peaks of Tb3+ and CsPbI 3 at different positions respond differently to temperature stimuli, we studied the potential application of those glasses as optical temperature detection tools in the temperature range of 80−480 K. More importantly, the results showed higher sensitivity than other tools, with the maximum absolute and relative temperature sensitivities reaching as high as 0.034 K−1 and 1.78 % K-1, respectively. This work is expected to provide an effective method for the application of CsPbX 3 in high-performance optical temperature sensing materials. [ABSTRACT FROM AUTHOR]

Abstract Particles with a diameter of <2.5 μm (PM 2.5) have serious adverse-effects on human health, which have caused widespread public concern in recent decades. Currently, most of the existing research on PM 2.5 have used linear regression analysis; very few studies on the subject have been conducted using non-linear models. This study adopts a panel threshold model, which is seldom used in environmental studies, to examine the non-linear effects of environmental regulation and economic growth on PM 2.5 in 30 OECD countries, and we also explore the key driving socio-economic factors for PM 2.5 emissions. The results of our analysis show that, along with an increase in environmental policy stringency, PM 2.5 emissions first rise and then show no significant correlations, and thus a reduction in emissions can be expected if current trends continue. As for GDP per capita, significant and negative correlations are found across the three phases divided by the panel threshold model, indicating a promoting effect for PM 2.5 mitigation. In addition, public expenditure on the air sector correlated positively with PM 2.5 concentrations, expanding the share of service economy reward to reduce air pollution, and urban population ratio exhibits an inverted U-shaped pattern. Future studies may shed more light on the regulation-PM 2.5 nexus, and more studies are needed to confirm the existence of bi-directional correlations between economic development and air pollution. Graphical abstract Unlabelled Image Highlights • Environmental regulation show different impacts on PM 2.5 at high-, mid- and low-level phases; • GDP per capita is negatively correlated with PM 2.5 at 1% level; • Expansion of service industry reduces pollution; • An inverted U-shaped relationship exist between urbanization and pollution. [ABSTRACT FROM AUTHOR]

[Display omitted] • The PLQY of CsPbBr 3 /Cs 4 PbBr 6 @PDMS achieve to 71%. • CsPbBr 3 /Cs 4 PbBr 6 @PDMS composite was studied for the first time and exhibit excellent optical properties. • The stabilit ies of CsPbBr 3 against heat, water and UV light have been greatly improved. • Under the excitation of blue chip, the color coordinate is extremely close to the standard of white light color coordinate. • The as-prepared film with the color gamut that could reach to 127% of NTSC 1953 and 95% of Rec. 2020 and applied in LCD successfully. All-inorganic perovskites have been considered next-generation color converters in the backlit due to their shining optical properties. However, structural instability severely limits their pragmatic applications. Here, CsPbBr 3 /Cs 4 PbBr 6 microcrystals (MCs) were successfully embedded in polydimethylsiloxane (PDMS) films by a facile two-step method. As-prepared PDMS films containing CsPbBr 3 /Cs 4 PbBr 6 MCs (CsPbBr 3 /Cs 4 PbBr 6 @PDMS) obtain high brightness and excellent stability. Meaningfully, the PDMS films not only serve as a double protective matrix that can be used to improve the stability of CsPbBr 3 /Cs 4 PbBr 6 MCs, but also a flexible substrate with high transparency that allows the CsPbBr 3 /Cs 4 PbBr 6 @PDMS films to be used as color conversion materials for backlit displays. To our surprise, when PDMS is coated with CsPbBr 3 /Cs 4 PbBr 6 MCs, the water, thermal and photostability are greatly improved, while the photoluminescence intensity only lost by 10%. Furthermore, by mixing CsPbBr 3 /Cs 4 PbBr 6 MCs with K 2 SiF 6 :Mn4+ phosphors in PDMS, a monolithic film with high performance was obtained. Its color gamut can reach 127% of the NTSC 1953 standard and 95% of the REC. 2020 standard, exhibiting the bright prospects in the backlit display field. [ABSTRACT FROM AUTHOR]

In the face of the increasingly serious water pollution problem, sulfate radical-based advanced oxidation processes gradually developed due to their remarkable ability to degrade refractory organic pollutants. Spinel ferrite nanoparticles (NPs) and their nanocomposites (NCs) can be used as catalysts to activate peroxymonosulfate (PMS) with great catalytic performance, high stability, and reusability, which has attracted some attention of scholars in recent years. Firstly, the advantages and mechanisms of PMS activation induced by various spinel ferrite NPs and their NCs for organic pollutants removal are reviewed in this paper. Secondly, the influence factors of catalyst performance and PMS activation are discussed. Finally, the challenges of PMS activation induced by spinel ferrite NPs and their NCs are put forward and the direction of improvement is proposed. [Display omitted] • Recent advances of spinel ferrite NPs and their NCs in peroxymonosulfate activation are reviewed. • The frequently-used synthesis methods, activation mechanisms, and influence factors are discussed. • Challenges and the direction of improvement are provided. [ABSTRACT FROM AUTHOR]

The photo-Fenton-like catalytic process has shown great application potential in environmental remediation. Herein, a novel photo-Fenton-like catalyst of Bi 2 WO 6 nanosheets decorated hortensia-like CoAl-layered double hydroxides (Bi 2 WO 6 /CoAl-LDHs) was synthesized via hydrothermal process. The optimized Bi 2 WO 6 /CoAl-LDHs composite performed the high-efficiency photo-Fenton-like catalytic performance for oxytetracycline (OTC) removal (98.47%) in the mediation of visible-light and H 2 O 2. The comparative experiment, technical characterization and density functional theory calculation results indicated that the efficient photo-Fenton-like catalytic performance of Bi 2 WO 6 /CoAl-LDHs was attributed to the synergistic action of the Fenton-like process of cobalt ions in CoAl-LDHs, an internal electric field and the S-scheme heterojunction form between Bi 2 WO 6 and CoAl-LDHs, which could significantly promote the active substance formation and the photocatalytic process in the catalytic system. This study will stimulate the new inspiration of designing the efficient catalytic system for environmental remediation and other fields. [Display omitted] • Hortensia-like Bi 2 WO 6 /CoAl-LDHs composite was synthesized via hydrothermal process. • Optical-electrical properties and H 2 O 2 adsorption behavior of samples were calculated by DFT. • Bi 2 WO 6 /CoAl-LDHs composite exhibited high photo-Fenton-like catalytic activity of antibiotic. • An internal electric field and S-scheme heterojunction form between Bi 2 WO 6 and CoAl-LDHs. [ABSTRACT FROM AUTHOR]

Energy shortages and climate change call for the development of clean and sustainable energy. The development of green materials for clean energy storage and conversion is conducive to promoting the widespread use of clean energy. Conjugated microporous polymers (CMPs) have been synthesized with various structures and properties, which offer designability for the molecular structures and nanopores of conjugated skeletons. The research of CMPs in clean energy technologies is significant for the improvement of CMP-based materials and their application in energy and environmental engineering. CMPs have shown great potential for challenging energy and environmental issues such as gas adsorption, photocatalysis, solar energy conversion, and electrical energy storage and conversion. This review aims to summarize the advances of synthesis and design on CMPs, computer simulations on CMPs, and the applications of CMPs in the clean energy technologies including hydrogen evolution and storage, the adsorption and conversion of carbon dioxide, rechargeable batteries, supercapacitors, fuel cells, and photovoltaic cells. We also propose the challenges and potential chances of the synthesis and the clean energy applications of CMPs. [Display omitted] [ABSTRACT FROM AUTHOR]