期刊：
Chemical Engineering Journal,2023年465:142730 ISSN：1385-8947
通讯作者：
Zhou, Shuai(zs402606665@126.com)
作者机构：
[Zhou, Shuai; Duan, Yi; Xiang, Chao; Tang, Zhenping] Univ South China, Hunan Prov Key Lab Pollut Control & Resources Reus, Hengyang 421001, Peoples R China.;[Gao, Yuanyuan; Hua, Yilong; Zhou, Shuai; Wei, Fuxing; Zhu, Feiyu; Jiang, Tianyun; Tang, Zhenping] Univ South China, Hunan Prov Key Lab Rare Met Minerals Exploitat & G, Hengyang 421001, Peoples R China.;[Wang, Yayi] Tongji Univ, Coll Environm Sci & Engn, State Key Lab Pollut Control & Resources Reuse, Siping Rd, Shanghai 200092, Peoples R China.
通讯机构：
[Shuai Zhou] H;[Yayi Wang] S;State Key Laboratory of Pollution Control and Resources Reuse, College of Environmental Science and Engineering, Tongji University, Siping Road, Shanghai 200092, China<&wdkj&>Hunan Province Key Laboratory of Pollution Control and Resources Reuse Technology, University of South China, Hengyang 421001, China<&wdkj&>Hunan Province Key Laboratory of Rare Metal Minerals Exploitation and Geological Disposal of Wastes, University of South China, Hengyang 421001, China
摘要：
Although oxygen-containing functional groups generated during unavoidable aging play a key role in improving the adsorption performance of heavy metals by microplastics (MPs), little is known about the contribution of such groups to the interactions between highly toxic radioactive heavy metals and aged MPs. Here, we used a combination of batch experiments and density functional theory calculations to examine the effects and mechanisms of aging and the produced oxygen-containing functional groups, i.e., C═O, –OH, phenolic hydroxyl (–OHm), and –COOH, on the adsorption behavior of representative radionuclide uranium (U) on polystyrene (PS) MPs. The kinetic experimental results showed that the amount of U adsorption by the aged PS MPs was significantly higher than that of virgin PS MPs (P < 0.05). Binding-energy and thermodynamic data indicated that the affinity of PS MPs to a typical U species, i.e., uranyl, followed the order of PS═O–OHm > PS═O > PS–COOH > PS–OH > PS–OHm > virgin PS. Characterization and surface potential analyses demonstrated that the electronegative oxygen atoms in oxygen-containing functional groups in the aged PS MPs increased along with the aging time, and could serve as potential sites for electrostatic interactions with uranyl. Intramolecular interaction calculations confirmed that hydrogen bonding by oxygen-containing functional groups could strengthen the interactions between uranyl and aged PS MPs via electrostatic and polarization effects. Our findings provide an in-depth understanding of the role of aging in U adsorption by MPs, which is critical for assessing the fate of coexisting radionuclides and MPs in the environment, and their associated risks.
摘要：
Anchors constitute a common form of structural support in geotechnical engineering. Precise identification of ultra-early-stage (UES) anchoring quality is crucial to ensure the integrity of the secondary lining. To address grout defects in the UES of anchors, a calculation method for UES anchor wave velocity was introduced. Indoor experiments and numerical simulations were conducted for non-destructive testing (NDT) of anchors in the UES, analyzing time-domain waveform characteristics and wave velocity variations. A method for identifying grout defects in the UES of anchors was proposed. The results indicate that the proposed wave velocity calculation method offers a more precise estimation of UES wave velocity for anchors compared to the traditional approach. This enhancement enables a more precise evaluation of the development of solid phases in the anchoring medium. As the solid phase develops, the wave velocity and first wave amplitude of the anchor gradually decline, while the response time of the bottom reflection increases. Grout defects lead to amplified amplitudes in both time-domain and frequency-domain signals, accompanied by a heightened occurrence of peaks in the frequency domain. The waveform distortion region before the bottom reflection is caused by grout defects. In the time-domain signals of defective anchors, a waveform distortion region is observed before the bottom reflection. By assessing the magnitude of the absolute value of the ratio between the amplitude of characteristic reflection points within the distortion region and the amplitude of the first wave, effective identification of grout defects in the UES of anchors can be accomplished.
摘要：
The beneficial reuse of cement-treated waste sludge in construction sector is an intractable challenge in the context of sustainable development. To exploit the potential of magnesium oxychloride cement (MOC) as cementing binder in substitution for Portland cement, various inorganic/organic additives are imported to overcome the key defect of MOC – instability in water and improve the water resistance of MOC solidified sludge. To achieve this goal, the mechanical and microstructural studies by compressive strength, water immersion, shear strength, compressibility, X-ray diffraction and scanning electron microscopy tests are comprehensively examined. Key outcomes reveal that: (i) Compressive strength, shear strength and water resistance of MOC solidified sludge can be significantly improved by a reasonable dosage of chemical additives, especially for phosphoric acid (3%), citric acid (4%) and urea–formaldehyde resin (12%), (ii) Shear strength versus normal stress relationship can be well represented by the approximately linear function, while cohesion and internal friction angle show an upward tendency with standard curing age and later a downward trend with water immersion period, (iii) Yielding stress exhibits a tendency of first rise and then fall with curing age, but compression index has a trend of first decline and then increase, and (iv) Lamellar Mg(OH)2, rod-like/plate-like phase 5 and phase 3 are identified as the major hydrated products conducive to the excellent performance of additive-modified MOC solidified sludge. A better understanding of the improvement of chemical additives on MOC solidified sludge is helpful to synthesize MOC that exhibits properties suitable for application as a cementing binder.
摘要：
Electrocatalytic oxidation is commonly restricted by low degradation efficiency, slow mass transfer, and high energy consumption. Herein, a synergetic electrocatalysis system was developed for removal of various drugs, i.e., atenolol, florfenicol, and diclofenac sodium, as well as actual pharmaceutical wastewater, where the newly-designed single-atom Zr embedded Ti(4)O(7) (Zr/Ti(4)O(7)) and hierarchical CuFe(2)O(4) (CFO) microspheres were used as anode and microelectrodes, respectively. In the optimal reaction system, the degradation efficiencies of 40mg L(-1) atenolol, florfenicol, and diclofenac sodium could achieve up to 98.8%, 93.4%, and 85.5% in 120min with 0.1g L(-1) CFO at current density of 25mA cm(-2). More importantly, in the flow-through reactor, the electrooxidation lasting for 150min could reduce the COD of actual pharmaceutical wastewater from 432 to 88.6mg L(-1), with a lower energy consumption (25.67kWh/m(3)). Meanwhile, the electrooxidation system maintained superior stability and environmental adaptability. DFT theory calculations revealed that the excellent performance of this electrooxidation system could be ascribed to the striking features of the reduced reaction energy barrier by single-atom Zr loading and abundant oxygen vacancies on the Zr/Ti(4)O(7) surface. Moreover, the characterization and experimental results demonstrated that the CFO unique hierarchical structure and synergistic effect between electrodes were also the important factors that could improve the system performance. The findings shed light on the single-atom material design for boosting electrochemical oxidation performance.
通讯机构：
[Taotao Zeng] H;Hunan Province Key Laboratory of Pollution Control and Resources Reuse Technology, University of South China, Hengyang, 421001, Hunan, China
摘要：
The use of modified biochar for the remediation of heavy metal (HM) has received much attention. However, the immobilization mechanism of biochar to multiple HMs and the interaction of different forms of HMs with microorganisms are still unclear. K(2)HPO(4)-modified biochar (PBC) was produced and used in a 90-days immobilization experiment with soil collected from a typic lead-zinc (Pb-Zn) mining soil. Incubation experiments showed that PBC enhanced the transformation of Cd, Pb, Zn and Cu from exchangeable (Ex-) and/or carbonate-bound forms (Car-) to organic matter-bound (Or-) and/or residual forms (Re-). After scanning electron microscopy-energy dispersive X-ray spectrometer (SEM-EDS), X-ray diffractometry (XRD), fourier transform infrared (FTIR), thermogravimetric analysis (TGA) and X-ray photoelectron spectroscopy (XPS) analysis, the mechanisms of HM immobilization by PBC were proposed as precipitation (PO(4)(3-), HPO(4)(2-), OH(-) and CO(3)(2-)), electrostatic attraction, complexation (-COOH, -OH and R-O-H) and the indirect roles of soil parameter variations (pH, moisture and microbial community). Microbial community analysis through high-throughput sequencing showed that PBC reduced bacterial and fungal abundance. However, addition of PBC increased the relative proportions of Proteobacteria by 15.04%-42.99%, Actinobacteria by 4.74%-22.04%, Firmicutes by 0.76%-23.35%, Bacteroidota by 0.16%-12.34%, Mortierellomycota by 4.00%-9.66% and Chytridiomycota by 0.10%-13.7%. Ex-Cd/Pb/Zn, Car-Cd/Zn and Re-Cd/Pb/As were significantly positively (0.001<P≤0.05) correlated with bacterial phyla of Crenarchaeota and Methylomirabilota, and Re-Cu and Ex-/Car-/Fe-Mn oxide-bound (Fe-Mn-)/Or-As were significantly positively correlated (0.001<P≤0.05) with the bacterial phyla of Proteobacteria and Bacteroidota. While Car-Cd/Zn and Re-Pb/As were positively correlated (0.01<P≤0.05) with fungal phyla of Ascomycota, Glomeromycota, Kickxellomycota, Basidiomycota and Mucoromycota. The bacterial network contained more complex interactions than the fungal network, suggesting that bacteria play a larger role in HMs transformation processes. The results indicate that PBC is an effective agent for the remediation of HMs polluted soil in Pb-Zn mining areas.
