The dichromate ion (Cr2O72-) is a highly toxic and carcinogenic pollutant in wastewater, which requires accurate and rapid monitoring techniques. In this study, a water-stable copper-based metal-organic framework (Cu-OCH3 MOF) is developed as a fluorescent sensor for detecting Cr2O72- in aqueous media. The copper ions in this MOF exhibit mixed oxidation states of Cu2+ and Cu+, which is important for fluorescence detection. The MOF shows an excitation maximum at 310 nm and an emission maximum at 393 nm, with a quantum yield of 17.61% and a fluorescence lifetime of 9.3 ns. In an aqueous solution of Cr2O72- (1 mM, pH ≈ 4.68), the sensor achieves a quenching efficiency of approximately 95%, together with fast response, high sensitivity, a wide linear range (0.0209-1 mM), and a low detection limit of (6.27 ± 0.005) × 10-6 M. The sensing mechanism is based on the inner filter effect (IFE) and dynamic quenching effect (DQE), where the absorption band of Cr2O72- overlaps with both the excitation and emission spectra of the MOF, leading to efficient fluorescence quenching.

The Cu-OCH 3 MOF, synthesized via a solvothermal method, exhibits excellent fluorescence properties and stability for detecting Cr 2 O 7 2− in aqueous solution.

The unprecedented growth of electric vehicles featuring lithium-ion batteries has led to a significant increase in the amount of waste generated, posing pressing waste management challenges for both industry professionals and environmental regulators. To address these issues, conventional pyrometallurgical, hydrometallurgical, and direct recycling methods are commonly employed to promote sustainable battery development. However, these methods are often hindered by laborious purification processes and the generation of low-profit products such as Li2CO3, CoSO4, NiSO4, etc. Herein, an upcycling technology involving a low-temperature solid-to-solid reaction and water leaching procedures is introduced to transform spent LiCoO2 cathode materials into value-added cobalt sulfide-based electrocatalysts. The regenerated electrocatalysts exhibit exceptional performance in the oxygen evolution reaction, surpassing that of the benchmark RuO2 catalyst. This proposed upcycling method provides researchers with an alternative way to convert the metallic components of waste lithium-ion batteries into high-value Co-, Ni-, Fe-, and Mn-based catalysts.

Carbon dots (CDs) are zero-dimensional fluorescent carbon nanomaterials prized for their low toxicity, simple, low-cost preparation, tunable photoluminescence and good biocompatibility. This article systematically reviews recent advances in the application of CDs in food detection, outlining common synthesis methods (top-down and bottom-up approaches) and their respective advantages and limitations. The luminescence mechanisms of CDs (size-dependent emission, surface defect states and molecular fluorophores) and their sensing mechanisms are thoroughly discussed. This review also summarizes CDs-based sensors for detecting heavy metals, anions, pathogenic microorganisms, common food additives and functional food components, with a focus on key performance metrics (detection limit, linear range, selectivity) and their applications. By analyzing the limitations of existing CDs-based sensors, this article identifies major challenges: relatively low quantum yield, narrow linear detection ranges, frequent limitations to single-target sensing and constraints in scalable and high-purity production. Corresponding improvement strategies are proposed, including enhancing quantum yield through surface passivation and heteroatom doping, designing red/near-infrared emitters to reduce matrix interference, developing novel sensing mechanisms and exploring greener and scalable synthesis and purification routes. Through systematic analysis and optimization of CDs' properties, CDs are expected to become promising tools for rapid, accurate and low-cost food safety detection in the future.

An efficient, eco-friendly and cost-effective strategy for the recovery of precious metals from spent lithium-ion batteries (LIBs) is of great significance for the sustainable natural resource utilization and environmental protection. Herein, a low-temperature solid-to-solid reaction combined water leaching technology is proposed for the preferential extraction of Li from spent LiCoO2 batteries. In the solid-to-solid reaction, crystal water released from the oxalic acid dihydrate acts as a lubricant and initiates the reduction reaction to convert the spent LiCoO2 into water-soluble Li salts (LiHC2O4 or Li2C2O4) and water-insoluble CoC2O4. After water leaching, the collected Li-rich solution and the Co-rich residue are separately transformed into Li2CO3 and Co3O4. Additionally, a defect-enriched Co3O4 is prepared by water quenching process, exhibiting excellent performances towards oxygen evolution reaction. This work not only achieves a facile, low-cost and energy-saving strategy for recycling spent LIBs, but also proposes a vacancy-defected engineering route for electrocatalyst design in energy-related applications.

Synthesizing stable MOF materials with good adsorption capability in a relatively green way is well worth investigating. In this work, a stable Ce-UiO-66-NH2 MOF was constructed from Ce(iv) salts and a bifunctional ligand, 2-amino terephthalic acid, in a mixture of water and ethanol at room temperature. The MOF solid was fully characterized and its adsorption properties for methylene blue were investigated in detail. Ce-UiO-66-NH2 showed excellent removal ability of MB over a wide pH range, the adsorption process followed a pseudo-second-order kinetic model, and the isothermal adsorption data fit well with a Langmuir model with a maximum capacity of 427 mg g-1. Moreover, a spontaneous heat adsorption process was concluded from thermodynamic study, and this MOF sorbent can be reused for several cycles with its structural stability maintained. A possible mechanism for MB adsorption was also proposed. Ce-UiO-66-NH2 was synthesized in water and ethanol at room temperature for effective removal of MB in aqueous solution.

Copper nanoclusters (CuNCs) as a new type of probe for environmental contaminants are gaining increasing attention because of its low cost, superior water dispersibility, wide availability and excellent optical properties. Compared with the other probes such as quantum dots and organic dyes, CuNCs show much more potential in practical application for their excellent photostability, large Stokes shift, low toxicity and other preponderance, especially in the fields of biosensing and environmental monitoring. Recently, the template-assisted synthesis of metal nanoclusters (MNCs) has been widely studied. A variety of templates such as proteins, small thiol molecules, polymers, and DNA with different spatial configuration have been used for the preparation of MNCs so far. This review primarily described recent advances in CuNCs in terms of the synthesis of CuNCs from different templates, the methods to improve the fluorescence (FL) properties of CuNCs, as well as the basic detection mechanisms based on the FL properties or catalytic properties. Finally, to promote the practical application of CuNCs probes, the challenges and prospects of CuNCs multifunctional probes are also discussed.

With the increase of agricultural production, the utilization of biomass waste has become the focus of current research. In this study, Si-containing carbon dots (Si-CDs) were prepared from peanut shells by one-pot hydrothermal method. These Si-CDs exhibit peroxidase-like activity and can catalyze H 2 O 2 oxidation of 3,3′,5,5′-tetramethylbenzidine (TMB) to produce a chromogenic reaction, while cysteine (Cys) can reduce the oxidation product of TMB (ox-TMB) to discolor it. A method for the determination of Cys using Si-CDs as peroxidase was developed. In addition, the effect of environmental factors on the enzyme-like reaction was investigated. The experimental results showed that the best catalytic effect was achieved at pH = 2.5, reaction temperature of 60 °C, and reaction time of 55 min when the concentrations of TMB and H 2 O 2 were 5 mmol·L −1 and 2.75 mmol·L −1 , indicating that Si-CDs still have the potential for enzymatic activity in extreme environments. The decrease in absorbance of the system (ΔA) showed a good linear relationship with Cys in the range of 5–100 μmol·L −1 , and the limit of detection was 0.037 μmol·L −1 . This sensor was successfully used for the determination of edible Cys content.

Hydroquinone (H2Q) present in water is becoming a growing problem in both daily life and industry, with various harmful effects on human health. Therefore, the detection of H2Q is very important. The Carbon dot-based sensor is considered an effective method to detect H2Q. In this work, Pericarpium citri reticulatae carbon dots (P-CDs) were synthesized by a one-pot hydrothermal method for wide linear sensing of H2Q. An orthogonal test was used to expand the active site and fluorescence properties of P-CDs. Under optimal conditions, the P-CDs exhibit an extremely stable blue fluorescence and a quantum yield (QY) of up to 15.4%. In the range of 5-1000 mu M, compared with the currently reported carbon dot-based H2Q sensors, the fluorescence intensity (FL) of P-CDs shows good linearity with the variation of H2Q concentration and a higher linear range. Moreover, the sensor demonstrates a low detection limit of 0.058 mu M. The possible detection mechanism is based on the synergistic action of static quenching and IFE. This method has been successfully applied to the determination of H2Q in real samples, and the P-CDs-based sensor has the potential to detect H2Q in various complex scenes.

以废弃的木质素为前驱体,采用水热法,绿色、便捷地制备了木质素碳点(L-CDs).利用透射电子显微镜、紫外可见分光光度计、傅里叶红外光谱、荧光光谱对L-CDs形貌和光学性质进行了研究.结果表明,制备的碳点具有较小的尺寸,尺寸主要分布在2～4 nm,平均粒径为3.2 nm,其表面有大量的羟基等含氧基团,表现出良好的分散性,最大激发波长与最大发射波长分别为370 nm和469 nm.L-CDs在365 nm紫外灯的照射下发出强烈的蓝色荧光,以硫酸奎宁为参比,L-CDs的荧光量子产率为12％,与多数已报道的生物质碳点具有可比性.通过对反应条件进行优化,L-CDs对水中Fe3+传感灵敏,检测的线性范围为5～400 μmol/L,检测限为1.69 μmol/L,其在实际水样的检测中仍有着较高的线性相关性.L-CDs在中性及碱性环境中有较强的荧光强度,有望用于自然水样中其他有机污染物的检测.

Developing non-noble metal catalysts for methanol oxidation in fuel cells is of importance. In this work, Ni-MOF-74 was synthesized through a simple solvothermal method and fully characterized. The as-made Ni-MOF-74 modified carbon paste electrode (Ni-MOF-74/CPE) was applied for methanol electrooxidation reaction in 0.1 M NaOH solution. Ni-MOF-74 had high electrochemical stability and exhibited good electrocatalytic property for methanol oxidation, a mechanism for the reaction was proposed, the current density increases impressively on Ni-MOF-74/CPE compared with carbon paste electrode, and a really high catalytic rate constant (k(cat)) of 8.1x10(5) cm(3) . mol(-1) . s(-1) was obtained in this work. The given results indicate that Ni-MOF-74 can be a promising candidate of electrocatalysts for direct methanol fuel cells (DMFCs).

余热锅炉是催化裂化装置中重要的节能设施.由于余热锅炉省煤器经常发生泄漏,又不能单独切出,因此会影响安全生产和节能效益.文章针对上述问题分析了高温烟气取热不充分、炉膛内温度测点设计分布不均匀、激波吹灰系统故障率高、省煤器失效等原因.为了保证余热锅炉稳定有效的运行,对装置进行了一系列技术改造,包括更新省煤器布置,新增1台给水预热器,增加温度、压力测量点,吹灰系统进行升级等.经过改造,优化了操作,方便了检修,降低了维修费用,提高了余热锅炉的运行效能.

阐述了中国石油化工股份有限公司金陵分公司3.5 Mt/a催化裂化装置烟气脱硫脱硝系统核心设备投运后出现的腐蚀状况.该装置烟气洗涤塔在投用4个月后,顶部塔壁局部区域陆续发生了多处腐蚀穿孔,蚀孔周围塔壁出现了严重的腐蚀减薄现象,筒体壁厚由原来13.0 mm局部减薄到5.5 mm.从设备运行的环境、设备腐蚀的机理、设备设计制造的结构、选用的材料、施工质量等方面对烟气洗涤塔顶部塔壁的腐蚀原因进行了分析,认为SO3/H2SO4和HNO3酸液是造成腐蚀的主要介质,腐蚀环境中水气pH值达2.5 ～3.5,呈强酸性.针对这些问题提出将设备筒体材质升级为304L、降低原料硫含量、改进工艺操作参数、加强腐蚀监控等整改措施,2014年3月装置停工检修中更换了烟气洗涤塔上部筒体,材质选用304L,目前设备运行良好.

SINOPEC Jinling Company modified its start-up procedures of flue gas expander train of the No.1 FCCU to minimize the surge to the local power grid at the start-up of flue gas expander train.The expander is first impulse rotated to the 80%of the rated speed of the train before start-up of motor so as to reduce the start-up current of the motor,shorten the start-up time and ensure the safe operation of other equipment in the power grid.The procedures for impulse start-up of expander-air blower-motor train are analyzed and critical operation procedures are highlighted.Improvements are recommended to minimize the impact of start-up speed on critical parameters.

Flue gas expander is the major energy-saving equipment in fluidized catalytic cracking unit (FCCU).Its operation has a direct impact on the energy consumption of the unit.The long-term stable opera- tion of the expander is even more critical for the unit without back-up air blower.The analysis of rotor dynamic balance testing,space between different parts and rotor alignment as well as start-up procedures are analyzed and improvement measures are proposed to enhance the reliability of the flue gas expander.