关键词：
S -type heterostructure;Tetracycline hydrochloride;Photocatalysis;tc-COF
摘要：
Photocatalytic oxidation is a promising technology for wastewater treatment. It is a more desirable method than other conventional wastewater treatment approaches due to its low cost, environmental friendly, and capability to completely degrade pollutants into environmentally safe products under appropriate conditions. Among some photocatalysts, covalent organic frameworks with high photoactivity are recognized as stable and feasible materials for this purpose. In this work, highly-effective photocatalyst of S-type heterostructure tc-COF was successfully synthesized by using ultrasonic delamination treatment sp2c-COF nanosheets (sp2c-NS) and py-NH2COF nanosheets (Py-NH2-NS) via a secondary solvent heating method. The preparation was initiated by synthesizing sp2c-COF and py-NH2-COF successfully adopting pyrene templates by solvothermal method. The study focused on physicochemical characterization and photocatalytic activity of tc-COF. The photocatalytic ability of tc-COF was carried out to degrade tetracycline under visible light. The results indicate that tc-COF not only shows excellent photocatalytic activity for tetracycline degradation of 94.8 % at 90 min under visible light illumination, but also has good photocatalytic degradation performance at wide initial pH values, coexisting ions, and actual water sources. Surprisingly, it has excellent stability and recyclability, it can afford high oxidative degradation (87.3 %) even after 5 successive recycles. The degradation mechanism was discussed by various methods such as active species trapping experiment, electron paramagnetic resonance determination and related electrochemical analysis. In addition, the main degradation intermediate products and the possible pathways of TC degradation were detected and proposed according to LC - MS technology. This work provided a new strategy for the preparation of hetero-structured COF which could be served as an advantageous photocatalyst for the treatment of pharmaceutical industry wastewater.
摘要：
Pyrene-based covalent organic frameworks (sp(2)c-COF and Py-NH2-COF) were successfully prepared via a solvothermal route. Upon the irradiation of visible light, COFs were used to degrade tetracycline hydrochloride (TC) in aqueous solution. The results showed that sp(2)c-COF exhibited much better photocatalytic activity than Py-NH2-COF. 73.5 and 3.1% TC could be degraded within 90.0 min with the initial concentration of 20 mg/L via sp(2)c-COF and py-NH2-COF under visible-light irradiation, respectively. The influence of bond connection types on the visible-light catalytic ability of COFs was explored. Electrochemical impedance spectroscopy (EIS) results proved that sp(2)c-COF had a higher photogenerated electron-hole separation efficiency. X-ray photoelectron spectroscopy (XPS) and Mott-Schottky plots revealed that the band gaps of sp(2)c-COF and Py-NH2-COF were 1.98 and 2.28 eV, respectively, resulting in sp(2)c-COF having a higher electron carrier transport efficiency. Importantly, sp(2)c-COF exhibits good reusability, affording 70.3% degradation efficiency even after 5 successive recycles. Active species trapping experiments and electron paramagnetic resonance (EPR) and electrochemical analyses were performed to consult the proposed degradation mechanism. This work indicates that the COF with C=C bonds could improve electron hole separation and electron carrier transport more effectively than the COF with C=N bonds in the photocatalytic process, which led to a more effective way of transmission of pi conjugation across the two-dimensional (2D) lattice and thus enhanced the electron delocalization. So it was more beneficial for the degradation of tetracycline.
摘要：
A fluorescent magnetic chitosan-based hydrogel (FMCH) incorporating Amino-Functionalized Fe3O4 nano-particles (AF-Fe3O4 NPs) and cellulose nanofibers (CNFs) modified with carbon dots (CDs) was successfully synthesized via the crosslinking method. The FMCH was used as an adsorbent for removing Cr (VI) from aqueous solution and it exhibited encouraging adsorption performance for Cr (VI). The composition and structure of FMCH were characterized and its Cr (VI) sorption performance was evaluated. The results demonstrated that this hydrogel had 3D porous structures and a higher adsorption ability of Cr (VI). The maximum adsorption capacity of this hydrogel was measured to be 212.1 mg/g at 25 degrees C and pH 5.0. The performance of the FMCH in Cr (VI) adsorption was evaluated through a contrast experiment with the normal chitosan hydrogel without CNFs and AF-Fe3O4 NPs. The effect of the initial concentration of Cr (VI) and contact time were also evaluated. The results confirmed that the adsorption isotherm was according to the Freundlich model, and the adsorption kinetics followed the pseudo-second-order model. Furthermore, as a fluorescent sensor for Cr (VI), the detection sensi-tivity and selectivity were examined. The quantitative detection of Cr (VI) was achieved in the linear range of 20-800 mg/L. Meantime, the mechanism for highly efficient adsorption and detection of FMCH for Cr (VI) was analysed by FTIR and XPS. These results showed that the excellent sorption and sensing abilities of Cr (VI) may be mainly attributed to the porous structures which provided many active sites and ion transport channels and the additional AF-Fe3O4 NPs and CNFs modified with CDs improving the sorption ability of Cr (VI) and providing a rapid visual response to Cr (VI). It showed that the FMCH can be widely used for Cr (VI) detection and removal in wastewater.
期刊：
Chemical Engineering Journal,2023年470:144087 ISSN：1385-8947
通讯作者：
Xin Guo<&wdkj&>Yiqiang Wu
作者机构：
[Zhang, Xuefeng; Huang, Huijian; Qi, Xinmiao; Zhang, Ning; Wang, Yuanlan; Guo, Xin] College of Science, Central South University of Forestry and Technology, Changsha 410004, China;Yuelushan Laboratory Non-wood Forests Variety Innovation Center, Changsha 410004, China;[Qiao, Jianzheng; Wu, Yiqiang] College of Materials Science and Engineering, Central South University of Forestry and Technology, Changsha 410004, China;[Peng, Junwen] College of Science, Central South University of Forestry and Technology, Changsha 410004, China<&wdkj&>Yuelushan Laboratory Non-wood Forests Variety Innovation Center, Changsha 410004, China
通讯机构：
[Xin Guo; Yiqiang Wu] C;College of Science, Central South University of Forestry and Technology, Changsha 410004, China<&wdkj&>College of Materials Science and Engineering, Central South University of Forestry and Technology, Changsha 410004, China
摘要：
To address the pollution of antibiotics in water resources, a novel cellulose nanofibrils modified with carbon dots-graft-polyacrylamide/Zeolitic imidazolate framework-8 composite hydrogel (CZCH) was synthesized in this study for simultaneous adsorption and detection of tetracycline (TC). The morphology, structure, fluorescent properties, and adsorption and sensing capabilities of CZCH were comprehensively characterized using various analytical techniques. The results demonstrated the CZCH's remarkable adsorption capacity for TC that reached a maximum of 810.36 mg/g. The Langmuir model provided an excellent fit for the adsorption isotherm, while the pseudo-secondary model accurately described the adsorption kinetics. Thermodynamic analysis revealed that the adsorption process was characterized by an endothermic reaction. Impressively, the CZCH maintained 85.6% retention of its initial adsorption capacity even after undergoing five consecutive adsorption/desorption cycles. Moreover, the synthesized CZCH exhibited blue fluorescence with an absolute quantum yield of 5.1%, enabling selective and efficient detection of TC with a low limit of detection of 0.09 μg/L. Furthermore, the mechanism underlying the adsorption and detection of TC by CZCH was elucidated. Cost analysis confirmed that CZCH had a significantly lower cost of CNY 0.07 per gram of TC removal compared to activated carbon, which costs CNY 5.74. Thus, this study presents a sustainable approach for synthesizing a low-cost and multifunctional adsorbent that can be employed for the adsorption and detection of antibiotics.
通讯机构：
[Wang, WL; Wang, YL] C;Cent South Univ Forestry & Technol, Coll Sci, Changsha 410004, Hunan, Peoples R China.
关键词：
Cr(6+) and carmine;Electron beam irradiation;Heterostructure;In(2)S(3)-CdIn(2)S(4)@X(X = Ag, Ag(3)PO(4), AgI);Photocatalysis
摘要：
Ternary heterostructure nanotubes of In2S3-CdIn2S4@X(X=Ag, Ag3PO4, AgI) were synthesized with enhanced photocatalytic activity for efficiently degrading pollutants. Electron beam irradiation was employed to artificially introduce interface defects to the heterostructure nanotubes. The experimental results for degrading carmine and Cr(6+) under visible light irradiation showed that the photocatalytic efficiency of In2S3-CdIn2S4 was improved to some extent by the introduction of silver compounds. DRS results confirmed that the band gaps of In2S3-CdIn2S4 were reduced to 1.62eV and 1.58eV by introducing Ag3PO4 and AgI, respectively. Interestingly, the band gap of In2S3-CdIn2S4@AgI after electron beam irradiation was further reduced to 1.56eV, resulting in that the degradation time of both Cr(6+) and carmine by In2S3-CdIn2S4@AgI after high-energy electron beam irradiation was shortened to only 5min. The XRD spectra of the photocatalysts after five cycles could maintain the original crystal form to a large extent. The OH stretching vibration peaks of In2S3-CdIn2S4@AgI after electron beam irradiation at 3387cm(-1) became wider and sharper, thus indicating that the number of free hydroxyl groups on the heterostructure surface significantly increased. PL results showed that electron beam irradiation could significantly reduce the PL emission peak and enhance the utilization of photogenerated charge carriers. EIS results further confirmed that In2S3-CdIn2S4@AgI processed by electron beam irradiation had higher photogenerated electron-hole separation efficiency. Based on the experimental results, a feasible reaction pathway and photocatalytic mechanism for the degradation of carmine was investigated. ESR results showed that the main active groups in the whole photocatalytic system were *O2(-) and h(+).
摘要：
In order to verify the properties of Konjac-kappa-Carrageenan mixed gel, some effects were studied in this paper, including kappa-Carrageenan-Konjac on their mixtures viscosity, temperature, heating time, concentration, storage temperature and time, KCl, CaCl2 and NaCl concentration in storage condition. The results showed that great synergism interaction existed among kappa-Carrageenan and Konjac gum (such as viscosity and strength) for the action of molecular power. Moreover, the suitable conditions of gelation formation were mixed gel concentration 1.0%, 80 degrees C water for 30 minutes, and then at room temperature for 6h, storage temperature (refrigeration, -5 similar to 18 degrees C), KCl concentration 0.1%, CaCl2 concentration 0.1%similar to 0.4% and NaCl concentration 0.6%similar to 0.8%. These results could be theoretical reference for mixed gel application in food industry.
摘要：
The reaction of AgNO3, 4,4'-bipyridine (bpy)/flexible 1,2-di(4-pyridyl)ethylene (dpe), diphenic acid (H(2)da) in acetic acid/alcohol aqueous solution produces, respectively, block-like crystals of [Ag-2(bpy)(2)(Hda)(2)](HAc)(2) center dot 2H(2)O (1), and [Ag-2(dpe)(2)(da)]center dot 4H(2)O (2) at room temperature. Both the above-stated compounds consist of parallel 1D infinite cationic chains, [AgL](infinity) (L=bpy and dpe), interspersed with organic da(2-) anions which play the role of charge compensation in the crystal structure. The lattice water molecules are situated among these chains, and stabilized by rich hydrogen-bonding interactions, playing a role in the orientation of the da2- in the crystal packing. Optical absorption properties and band gaps of title compounds were determined with UV/Vis/NIR diffuse reflectance spectra, and the results show that the E-g can be assessed at 3.3 eV for both compound 1 and 2. CCDC: 768737, 1; 768736, 2.
