Porphyrin-based chemistry has reached an unprecedented period of rapid development after decades of study. Due to attractive multifunctional properties, porphyrins and their analogues have emerged as ...multifunctional organometals for environmental and energy purposes. In particular, pioneer works have been conducted to explore their application in pollution abatement, energy conversion and storage and molecule recognition. This review summarizes recent advances of porphyrins chemistry, focusing on elucidating the nature of catalytic process. The Fenton-like redox chemistry and photo-excitability of porphyrins and their analogues are discussed, highlighting the generation of high-valent iron oxo porphyrin species. Finally, challenges in current research are identified and perspectives for future development in this area are presented.
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•Comprehensive study of porphyrin species in environmental and energy applications.•Mechanism of the generation of high-valent iron oxo porphyrin species.•Photoexcitability of porphyrins as efficient photocatalysts to produce 1O2 or O2−.•Challenges and future prospects in current researches.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
Plant invasion potentially alters ecosystem carbon (C) and nitrogen (N) cycles. However, the overall direction and magnitude of such alterations are poorly quantified. Here, 94 experimental studies ...were synthesized, using a meta-analysis approach, to quantify the changes of 20 variables associated with C and N cycles, including their pools, fluxes, and other related parameters in response to plant invasion. Pool variables showed significant changes in invaded ecosystems relative to native ecosystems, ranging from a 5% increase in root carbon stock to a 133% increase in shoot C stock. Flux variables, such as above-ground net primary production and litter decomposition, increased by 50-120% in invaded ecosystems, compared with native ones. Plant N concentration, soil graphic removed and graphic removed concentrations were 40, 30 and 17% higher in invaded than in native ecosystems, respectively. Increases in plant production and soil N availability indicate that there was positive feedback between plant invasion and C and N cycles in invaded ecosystems. Invasions by woody and N-fixing plants tended to have greater impacts on C and N cycles than those by herbaceous and nonN-fixing plants, respectively. The responses to plant invasion are not different among forests, grasslands, and wetlands. All of these changes suggest that plant invasion profoundly influences ecosystem processes.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NMLJ, NUK, OILJ, PNG, SAZU, SBCE, SBMB, UL, UM, UPUK
A microbial fuel cell system with intimately coupled photocatalytic-electrogenic anode (photocatalytic-MFC) was proposed for the synergetic degradation of 2,4,6-trichlorophenol (2,4,6-TCP) which has ...a structure of three chlorine groups connecting to a phenol ring and is well recognized as a recalcitrant pollutant for its high toxicity, bioaccumulation and persistence. The photocatalytic-electrogenic anode was prepared by coating mpg-C3N4 on a carbon felt anode, followed by inoculating with municipal sewage and acclimating with 2,4,6-TCP at gradient concentrations. Improved TCP degradation was achieved, showing 79.3% of TCP removal in 10 h with an original concentration of 200 mg L−1, which was higher than that obtained with the unilluminated MFC (66.0%) and the photocatalytic-only process (56.1%). The coupled photocatalytic-electrogenic process demonstrated different degradation pathways compared with the photocatalytic-only process, with one open-chain compound (2-chloro-4-keto-2-hexenedioic acid, 2-CMA) detected in the photocatalytic-MFC system. Microbial community analysis revealed that Pseudomonas, instead of Geobacter observed in the unilluminated MFC bioanode, dominated in the photocatalytic-electrogenic anode MFC biofilm, which might be responsible for enhanced current generation in the coupled system. In addition, biofilm rich with Rhodococcus on air-cathode was also responsible for the enhanced TCP removal. This research provides an efficient strategy for the treatment of wastewater with recalcitrant contaminants by intimate-coupling of the photocatalytic and the electrogenic processes.
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•An MFC with intimately coupled photocatalytic-electrogenic anode was proposed.•TCP removal of 79.3% was achieved within 10 h with the coupled system.•An open-chain compound was detected in the coupled MFC system for TCP degradation.•Pseudomonas was dominated in the coupled anode biofilm for efficient TCP removal.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Polyether polyols can improve the performance of waterborne epoxy curing agent. In this paper, intermediates were synthesized from polyether triols with epoxy resin E‐51 and introduced into the epoxy ...curing agent by reacting with TETA. This paper focuses on the process of synthesizing the intermediates. The 2K waterborne epoxy coating film prepared with polyether triols‐modified waterborne epoxy curing agent exhibits desirable corrosion protection capacity and neutral salt spray resistance up to 600 h. In addition, the 2K waterborne epoxy coating film prepared using the modified waterborne epoxy curing agent with polyether triols displayed improved surface appearance, mechanical properties, and water resistance.
Curing schematic of waterborne epoxy dispersion and polyether triols modified waterborne epoxy curing agent.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
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•Joint application of Fenton’s reagent and CaO improves sludge drying performance.•Conditioners reduce the amounts of both free and bound water in dewatered sludge.•Conditioners ...create porous structure and efficiently promote sludge heat transfer.•Emissions of S- and N-containing gases during sludge drying are greatly suppressed.•Decreased odor emissions are related to the variations in sludge-S and -N species.
Joint application of Fenton’s reagent and CaO can dramatically enhance sludge dewaterability, thus are also likely to affect subsequent thermal drying process. This study investigated the synergistic effects of the two conditioners on the thermal drying behavior of sewage sludge and the emission characteristics of main sulfur-/nitrogen-containing gases. According to the results, Fenton peroxidation combined with CaO conditioning efficiently promoted sludge heat transfer, reduced the amounts of both free and bound water, and created porous structure in solids to provide evaporation channels, thus producing significant positive effects on sludge drying performance. In this case, the required time for drying was shortened to one-third. Additionally, joint usage of Fenton’s reagent and CaO did not increase the losses of organic matter during sludge drying process. Meanwhile, they facilitated the formation of sulfate and sulfonic acid/sulfone, leading to sulfur retention in dried sludge. Both of Fenton peroxidation and CaO conditioning promoted the oxidation, decomposition, and/or dissolution of protein and inorganic nitrogen in sludge pre-treatment. As a consequence, the emissions of sulfurous and nitrogenous gases from dewatered sludge drying were greatly suppressed. These indicate that combining Fenton peroxidation with CaO conditioning is a promising strategy to improve drying efficiency of sewage sludge and to control sulfur and nitrogen contaminants during sludge thermal drying process.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
According to 3-D magnetic circuit of the transverse flux permanent magnet linear generator (TFPMLG), the area of end flux leakage is divided into several zones, and the analytical expression of axial ...end flux leakage is derived through conformal transformation. The linear machine equivalent stiffness factor is derived through the calculation of detent force. Combining the linear machine with mechanical resonance property of thermoacoustic electric generation system, the computing method on resonance spring parameters of the system is provided. A 3-D finite-element model of TFPMLG is built to analyze the flux leakage distribution. The experimental results of the linear machine verified the validity of detent force and stiffness factor theoretical derivation; the research on axial end flux leakage and resonance spring parameters provides a valuable reference to other types of linear machines.
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•A novel mechanochemically pretreatment method for efficient LIBs recycling.•Activated radical from persulfate activation facilitates the mechanochemical reaction.•The synergistic ...effect of mechanochemistry and free radicals was simulated by AIMD.
A novel mechanochemically assisted persulfate activation method was proposed in this study to enhance the leaching of valuable metals from lithium-ion batteries by combining ball-milling, advanced oxidation processes and sucrose reduction. By optimizing leaching parameters including temperature, pH, milling time and solid-to-liquid ratio, high leaching efficiencies of 97.1%, 94.0%, 87.6% and 93.8% can be achieved for Li, Ni, Co and Mn respectively. In the mechanochemical process, the breakage of covalent bonds in cathode material is facilitated by free radicals generated from zero valent iron activated ammonia persulfate as well as mechanochemical activation. To further explore the role of free radicals, the mechanism of ammonia persulfate activation by zero valent iron was elucidated, and SO4•- was identified as the dominant reactive oxygen species in the mechanochemical process. Meanwhile, the synergistic effect of mechanochemically driven crystal dissolution and sulfate radical facilitated bond cleavage was revealed by ab initio molecular dynamics simulation. Moreover, the released metal was reduced by sucrose to a lower valent state of high solubility to promote transfer to the aqueous phase during the subsequent leaching process with dilute sulfuric acid. In this work, the insight on the mechanism of mechanochemical processes strengthened by free radicals may provide an inspiration for the recovery of valuable metals from LIBs.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
As a typical urban mineral resource, spent lithium ion batteries (LIBs) contain abundant valuable metal resources, such as Li, Co, Mn and Ni, but facile separation with environmental benignity is ...challenging. Although the organic acid leaching method has been proposed to address this issue, its application is still hindered by the limitations of low leaching efficiency, high acid consumption and relatively long treatment time. Here a green and simple intensifying method is demonstrated for facile leaching of high value metals from spent LIBs using subcritical water, which combines glucose as a reductant and acetic acid as a leaching agent. More than 97% of the four metals were effectively leached from spent LIBs in 67 min under optimal conditions. Furthermore, the mechanism of the hydrothermal reaction is elucidated. Hydrothermal activation can accelerate the dissociation of the crystal structure, and the large ionization constant of acetic acid assists in maintaining a constant supply of protons in the solution. In addition, glucose can promote the reduction of dissolved metal ions to a more soluble low-valent state, and decompose to other low molecular weight organic acids that can coordinate with metal cations to promote the dissolution of metals from the cathode material. As a result, the proposed use of organic acids and glucose in subcritical reaction manifests an effective, ecofriendly, economic and sustainable strategy for metals recovery of spent LIBs.
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•A subcritical method for metals recovery from spent lithium ion batteries is proposed.•Large ionization constant of acetic acid maintains a constant supply of protons.•Glucose reduces dissolved metals to a more soluble low-valent state.•Coordination further promotes the dissolution of metals from the cathode material.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Inverted magnetorheological (MR) polishing device mainly use a magnetic sealing ring to collect polishing fluid. This collection method wears the wheel surface of the polishing wheel, affects the ...surface accuracy of the polishing wheel, and introduces machining error. In order to reduce this wear and improve recovery efficiency, a new type of collector using an air seal is proposed in this paper. Furthermore, testing method using six factors and a three-level orthogonal test table is used to study the structural parameters of the new collector. The flow fields affected by the different structural parameters were simulated, and the corresponding collection efficiency was analyzed. The results show that the air nozzle diameter has the greatest impact on the fluctuation value of the collector outlet flow, followed by the airflow velocity and nozzle spacing. Moreover, the structural parameters obtained from the orthogonal test were optimized using the control variable method. The minimum flow fluctuation and maximum flow at the collector outlet can be obtained when the nozzle diameter is 2.5 mm and the nozzle airflow velocity is 31 m/s.
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