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•Various morphologies of core–shell tungsten oxide@carbon composite electrodes were synthesized.•The urchin-like W18O49@C HCDI cathode achieved high SAC of 32.25 mg g−1 at ...1.2 V.•Excellent cycling stability over 200 cycles with negligible metal leaching was displayed.•Such core@carbon shell structure with particular morphology provides inspirations for future research.
W18O49 has been considered as a promising candidate for electrochemical applications, but it suffers from unsatisfactory electrical conductivity, low specific surface area, poor structural stability, and the corresponding morphology dependent capacitive deionization (CDI) performance has not been reported. Herein, we explored the novel composites of various morphologies of W18O49 encapsulated by a carbon shell (W18O49@C) as hybrid capacitive deionization (HCDI) cathode for water desalination. The as-obtained W18O49@C exhibited unique structures, allowing synergistic effects of ion intercalation and electric-double-layer capacitance, fast ion penetration, rapid electron transfer, and dissolution prevention of the active core materials. Among the three morphologies of W18O49@C, urchin-like W18O49@C (UWC) presented appropriate pore size distribution, the largest specific surface area and specific capacitance, the highest degree of graphitization and carbon content, consequently achieving excellent desalination capacity. Furthermore, an outstanding cycling stability over 200 cycles as well as a high charge efficiency and a low energy consumption were displayed for the UWC electrode. This study illustrates the great promise of urchin-like core–shell tungsten oxide@carbon composite in HCDI and paves a way for rational design of highly efficient and stable electrode materials for water desalination.
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•Versatile applications of TMP electrocatalysts in environmental fields were reviewed.•Synthetic approach and improvement strategies of TMP electrocatalysts were summarized.•The ...related mechanisms during reaction process of TMP electrocatalysts were discussed.•Challenges and prospect of TMP electrocatalysts toward environmental applications were presented.
Highly active, stable and low-cost electrocatalysts are critical to make environment-related electrocatalytic techniques commercially viable. Nanostructured transition metal phosphides (TMPs) have emerged as efficient and promising electrocatalysts in environmental applications owing to their tunable electronic structure, earth-abundance reserves as well as unique physiochemical properties. In this work, the up-to-date versatile applications of TMP electrocatalysts in environment-related fields were reviewed, including carbon dioxide electroreduction, nitrate electroreduction, urea electrooxidation, electrocatalytic treatment of organic wastewaters, and electroporation bacterial inactivation. In addition, various synthetic approach and improvement strategies of TMP electrocatalysts were summarized. Finally, future challenges and prospects of TMP electrocatalysts toward environmental applications were pointed out. This review should be of value to promote the development of TMP electrocatalysts and construct high-activity TMP electrocatalysts to tackle multiple environmental problems.
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•Degradation of SMX was positively related with activities of enzymes and microbes.•The combined biochar-compost would weaken each other's remediation effects.•HCGs increased the ...bacterial diversity but reducedthe bacterial richness.•LCGs enhanced the bacterial richness but reduced the bacterial diversity.•HCGs raised functional gene RAs of amino metabolism but lowered those of carbohydrate.
Biochar and compost, two common amendments, were rarely conducted to investigate their combined influence on enzymatic activities and microbial communities in organic-polluted wetlands. This article described the effects of biochar/compost on degradation efficiency of sulfamethoxazole (SMX) and ecosystem responses in polluted wetland soil during the whole remediation process. 1% biochar (SB1) increased degradation efficiency of SMX by 0.067% ascribed to the increase of dehydrogenase and urease. 5% biochar (SB5) decreased degradation efficiency by 0.206% due to the decrease of enzymes especially for dehydrogenase. 2% compost (SC2), 1% biochar & 2% compost (SBC3), both 10% compost (SC10) and 5% biochar & 10% compost (SBC15) enhanced degradation efficiency by 0.033%, 0.015% and 0.222%, respectively, due to the increase of enzymes and biomass. The degradation efficiency was positively related to biomass and enzymatic activities. High-throughput sequencing demonstrated that HCGs (SB5, SC10, SBC15) improved the bacterial diversities but reduced richness through introducing more exogenous predominance strains and annihilated several inferior strains, while LCGs (SB1, SC2, SBC3) exhibited lower diversities but higher richness through enhanced the RAs of autochthonal preponderant species and maintained some inferior species. Additionally, HCGs raised the RAs of amino and lipid metabolism gene but lowered those of carbohydrate compared with LCGs.
•FCDI was explored for phosphorus removal and recovery from low-strength wastewaters.•Operational conditions were systematically investigated.•Enrichment experiments were conducted to obtain a ...concentrated phosphorus stream.
Phosphorus (P) concentrations as low as 10 mg/L P can lead to eutrophication in natural waters. Meanwhile, phosphorus is an important and non-renewable resource for humans, animals and plants. This study investigated the removal and recovery of phosphorus from low-strength wastewaters by flow-electrode capacitive deionization (FCDI) to realize the sustainable utilization of phosphorus. Effects of different operating parameters on the performance of FCDI for phosphorus removal were systematically studied, including applied voltage, flow rate and flow direction of feed water, initial phosphorus concentration, carbon black content and initial pH value. Results showed that the applied voltage and initial pH value had great influence on the phosphorus removal efficiency. The removal efficiency of phosphorus reached about 97% when the operating parameters were optimized. The FCDI system possessed good removal performance of phosphorus after six consecutive cycling tests. In addition, the low concentration of feed phosphorus solution (100 mg/L P) could be effectively concentrated by 16 times after 11 h of operation through the enrichment experiment, leading to a final concentration of 16.8 mg/L P in feed solution and 1567 mg/L P in the aqueous phase of flow electrodes. To conclude, these results revealed that FCDI system is effective in phosphorus removal and recovery, and has great application prospects in treatment of phosphorous wastewaters.
Global climate change has attracted worldwide attention. The ocean is the largest active carbon pool on the planet and plays an important role in global climate change. However, marine plastic ...pollution is getting increasingly serious due to the large consumption and mismanagement of global plastics. The impact of marine plastics on ecosystem responsible for the gas exchange and circulation of marine CO2 may cause more greenhouse gas emissions. Consequently, in this paper, threats of marine microplastics to ocean carbon sequestration are discussed. Marine microplastics can 1) affect phytoplankton photosynthesis and growth; 2) have toxic effects on zooplankton and affect their development and reproduction; 3) affect marine biological pump; and 4) affect ocean carbon stock. Phytoplankton and zooplankton are the most important producer and consumer of the ocean. As such, clearly, further research should be needed to explore the potential scale and scope of this impact, and its underlying mechanisms.
•A question that marine microplastics pose threats to OCS has been raised.•Potential threats of microplastics to ocean carbon sequestration are discussed.•Consequences of microplastics on global OCS are also introduced.•Further research is needed to understand the scale and scope of this problem.
•Ferrate modified carbon felt cathode was innovatively used for heterogeneous EF process.•The Fe-CF/EF system exhibited excellent performance for chloramphenicol degradation.•The Fe-CF cathode ...exhibited good recyclability and outstanding practicability.•Toxicity assessment confirmed an efficient toxicity reduction after 60 min treatment.•Main reactive species and possible mechanism for CAP degradation were analyzed.
In this study, a novel and efficient heterogeneous electro-Fenton (EF) process with a potassium ferrate (K2FeO4) modified carbon felt (Fe-CF) cathode was developed for chloramphenicol (CAP) removal. The catalytic activity was assessed by the comparison of different systems and the effects of multiple operating parameters (K2FeO4 dosage, initial solution pH, applied current) and co-existing constituents. Results indicated that the Fe-CF cathode exhibited excellent performance for CAP degradation (almost 100% removal efficiency within 60 min) over a wide range of pH (pH 3–9) during heterogeneous EF ascribed to the synergistic effect of embedded iron species and porous graphitic carbon structure and effective utilization of the in-situ generated H2O2. Moreover, the Fe-CF cathode possessed good recyclability with low metal leaching (98.2% CAP removal efficiency after reused for 5 times) and outstanding real water application performance. The ∙OH and O2∙− were responsible for CAP degradation, while ∙OH played a main role. Moreover, the toxicity evaluation by E. coli growth experiments demonstrated an efficient toxicity reduction in this system. Overall, a novel heterogeneous EF functional cathode with superior performance was fabricated via a green, low-cost one-step method, which shows promising application potential for actual wastewater treatment.
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•The doping of Cu added and enhanced the generating routes of ROSs.•The proposed HEEF system exhibited high efficiency, stability and economy.•Free risk of secondary pollution of ...heavy metal (Cu) was proved.•Reasonable mechanism was proposed.•Degradation pathways were speculated with several typical intermediates identified.
The degradation of tetracycline (TC) in aqueous environment has been studied by a novel heterogeneous electro-Fenton (HEEF) process using Cu-doped Fe@Fe2O3 core–shell nanoparticles (CFF) as catalyst loaded on the nickel foam as cathode. CFF was synthesized by a facile two-step reduction method and aging process, and characterized by scanning electron microscope (SEM), transmission electron microscopy (TEM), scanning transmission electron microscopy mapping (STEM-mapping), X-ray diffractometer (XRD) and X-ray photoelectron spectroscopy (XPS). The effects of operating parameters, such as the initial pH of solution, the mass ratio of Cu/Fe and aeration mode, were investigated. The prepared CFF exhibited rapid degradation (98.1% within 2 h) and high mineralization efficiency of TC (89.8% after 6 h). Furthermore, the degradation of TC in solution remained over 90% till the seventh cycle, indicating the high stability of CFF. The mechanism of the HEEF process catalyzed by CFF was also proposed. Additionally, based on the identification of main representative by-products, plausible pathways for the mineralization of TC in aqueous solution by OH was speculated.
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•Biochar for mitigating GHG emissions is reviewed.•Activity and reactivity are significant for the removal of contaminants.•The involved removal behaviors and mechanisms are ...reviewed.•Potential negative aspects of biochar applications are also discussed.•Possible improvements and outlooks of biochar applications are proposed.
With increased interest in scientific investigations and large-scale applications of lignocellulosic biomass derived biochar for environmental management, a comprehensive understanding of its function in the fragile earth environment is urgently needed. The study on the relationship between biochar properties and potential applications requires continuing research. This review provides new insights into the state-of-the-art accomplishments in the utilization of biochar in environmental management and covers three perspectives: firstly, mitigation of greenhouse gas (GHG) emissions, such as sequestration of CO2 and CH4 in global carbon pools and mitigation of N2O emissions; secondly, pollution control, including adsorptive removal and reactive removal of inorganic and organic contaminants; thirdly, potential negative aspects of biochar applications, including contaminations originated from biochar, negative alterations to soil properties and soil biota, negative impacts of biochar on GHG emissions and negative impacts of biochar migration. From a unique and comprehensive environmental perspective, this article aims to provide a critical review of updated knowledge on both positive and negative impacts of biochar for environmental management, based on an exponentially increased number of publications on the topic over the past decade.
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•A novel WO3@W18O49 branched homojunction was fabricated for the first time.•The WO3@W18O49 branched homojunction exhibit superior interfacial charge separation.•The enhanced ...interfacial charge separation was confirmed by series experiments.•A novel design strategy for full-spectrum responsive photocatalyst is proposed.•The degradation pathway of 2,4-DCP is proposed.
Interfacial charge separation is a fundamental and crucial process in photoelectric conversion for composite photocatalyst. In this work, the interfacial charge separation performance was investigated on a nonmetallic branched homojunction, which is fabricated through solvothermal growth of W18O49 nanofiber (as branches) onto WO3 microrods (as backbones). The ultrafast transfer of photogenerated electrons from the WO3 backbones to the W18O49 branches across the contact interface was demonstrated by a series of experiments and characterizations. The contrast experiment showed that the WO3@W18O49 homojunction exhibited superior interfacial electron transfer capacity to the BiVO4@W18O49 heterojunction, the calculated interfacial charge separation efficiency of WO3@W18O49 was 51.3%, which was more than twice as that of BiVO4@W18O49 (24.2%). Upon localized surface plasmon resonance excitation by low-energy NIR photons, the full-spectrum light driven photo-degradation for 2,4-DCP was realized. The branched structure favors the enhancement of light scattering and absorbing. Meanwhile, the homojunction structure leads to a low impedance interface and increased electric conductivity. Thus, the WO3@W18O49 exhibited an enhanced photocatalytic performance under both full-spectrum and NIR light irradiation. This work provides a promising approach to design and fabricate novel photocatalysts with full-spectrum response ability and enhanced charge separation.
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