摘要：
Carbon nitride had unique structure and electronic properties, and had wide application prospects in the field of photocatalysis. However, the rapid photogenerated carrier recombination efficiency and low photocatalytic activity limit its use. Defect construction was considered to be an effective strategy to improve the photocatalytic activity of carbon nitride. In this paper, nitrogen defective carbon nitride was prepared by formic acid assisted pyrolysis. The formic acid was used to regulate the top atoms and effectively shorten the band gap. Second, the gas released during pyrolysis contributed to the construction of porous structures. SEM, TEM, BET, XPS were used to confirm the presence of nitrogen defective sites. When it was used to photocatalyze the degradation of tetracycline, the main antibiotic pollutant in Dongting Lake, the degradation rate of 95.1 % was achieved in 60 min. Compared with conventional carbon nitride, the degradation rate constants were 0.04751 min-1 and 0.02110 min-1, respectively. Compared with CN, the degradation rate constant of FCN-5 was increased 2.2 times. The photocatalytic degradation activity was verified by photochemical experiments. center dot O2- and 1O2 active radicals dominate the photocatalytic degradation process. The ecological safety of Dongting Lake water samples repaired by defective carbon nitride has been confirmed, and the toxicity of antibiotics to the germination and growth of legumes has been effectively alleviated. Five cycles of the experiments ensured that the material can be reused. The above work provided reference and basis for the development and design of defective carbon nitride for water body restoration in Dongting Lake basin.
关键词：
Constructed wetland;Nitrogen removal;Tidal flow;Macroporous zeolite spheres;Microbial structure and function
摘要：
Tidal flow constructed wetlands (TFCWs) enhance the process of microbial denitrification, while, the influence of substrate pore structure on denitrification are not clear. Herein, we prepare macroporous zeolite ball (MZ) by pore construction technique, and equipped as substrate in TFCWs, to explore the influence of MZ on the structure and function of microbial community. Results show ed that MZ has porous morphology both on the surface and inside. The removal rate of NH4+-N was 12% higher than that of the control. Surface characteristics of MZ provided more attachment sites for microorganisms. BugBase phenotypic and FAPROTAX prediction results showed that MZ had a wider ecological niche, and aerobic bacteria and anaerobic bacteria coexisted on the surface, the main denitrification functional bacteria are Massilia, Pseudarthrobacter, Hydrogenophaga, Acidovorax and Pseudomonas. This study is conducive for improving the purification efficiency of constructed wetland.
摘要：
Advanced oxidation technology represented by hydroxyl radicals has great potential to remove residual antibiotics. In this study, we systematically compared the metronidazole (MTZ) degradation behavior and mechanism in the UV and UV/H2O2 systems at pH 3.00 condition. The results show that the initial reaction rates were 0.147 and 1.47 mu M min(-1) in the UV and UV/H2O2 systems, respectively. The main reason for the slow direct photolysis of MTZ is the relatively low molar absorption coefficient (2645.44 M-1 cm(-1)) and quantum yield (5.9 x 10(-3) mol Einstein(-1)). Then, we measured k(MTZ,center dot OH) as 2.79 (+/- 0.12) x 10(9) M-1 s(-1) by competitive kinetics, and calculated k(MTZ,center dot OH) and [(OH)-O-center dot](SS) as 2.43 (+/- 0.11) x 10(9) M-1 s(-1) and 2.36 x 10(-13) M by establishing a kinetic model based on the steady-state hypothesis in our UV/H2O2 system. The contribution of direct photolysis and (OH)-O-center dot to the MTZ degradation was 9.9% and 90.1%. (OH)-O-center dot plays a major role in the MTZ degradation, and (OH)-O-center dot was the main active material in the UV/H2O2 system. This result was also confirmed by MTZ degradation and radicals' identification experiments. MTZ degradation increases with H2O2 dosage, but excessive H2O2 had the opposite effect. A complex matrix has influence on MTZ degradation. Organic matter could inhibit the degradation of MTZ, and the quenching of the radical was the main reason. NO3- promoted the MTZ degradation, while SO42- and Cl- had no effect. These results are of fundamental and practical importance in understanding the MTZ degradation, and to help select preferred processes for the optimal removal of antibiotics in natural water bodies, such as rivers, lakes, and groundwater
作者：
Su, Rongkui;Xie, Tianzhi;Yao, Haisong;Chen, Yonghua;Wang, Hanqing;...
期刊：
International Journal of Environmental Research and Public Health,2022年19(22):14968- ISSN：1661-7827
通讯作者：
Yiting Luo<&wdkj&>Yonghua Chen
作者机构：
[Xie, Tianzhi; Su, Rongkui; Yao, Haisong; Chen, Yonghua] Cent South Univ Forestry & Technol, Sch Environm Sci & Engn, Changsha 410004, Peoples R China.;[Dai, Xiangrong; Su, Rongkui] PowerChina Zhongnan Engn Corp Ltd, Changsha 410004, Peoples R China.;[Wang, Hanqing] Cent South Forestry Univ, Sch Civil Engn, Changsha 410018, Peoples R China.;[Wang, Hanqing] Hunan Engn Res Ctr Full Life Cycle Energy Efficie, Changsha 410018, Peoples R China.;[Wang, Yangyang] Henan Univ, Coll Geog & Environm Sci, Kaifeng 475004, Peoples R China.
通讯机构：
[Yiting Luo; Yonghua Chen] A;Authors to whom correspondence should be addressed.<&wdkj&>Business College, Hunan First Normal University, Changsha 410205, China<&wdkj&>Authors to whom correspondence should be addressed.<&wdkj&>School of Environmental Science and Engineering, Central South University of Forestry and Technology, Changsha 410004, China
摘要：
Phytoremediation could be an alternative strategy for lead (Pb) contamination. K. paniculata has been reported as a newly potential plant for sustainable phytoremediation of Pb-contaminated soil. Physiological indexes, enrichment accumulation characteristics, Pb subcellular distribution and microstructure of K. paniculata were carefully studied at different levels of Pb stress (0-1200 mg/L). The results showed that plant growth increased up to 123.8% and 112.7%, relative to the control group when Pb stress was 200 mg/L and 400 mg/L, respectively. However, the average height and biomass of K. paniculata decrease when the Pb stress continues to increase. In all treatment groups, the accumulation of Pb in plant organs showed a trend of root > stem > leaf, and Pb accumulation reached 81.31%similar to 86.69% in the root. Chlorophyll content and chlorophyll a/b showed a rising trend and then fell with increasing Pb stress. Catalase (CAT) and peroxidase (POD) activity showed a positive trend followed by a negative decline, while superoxide dismutase (SOD) activity significantly increased with increasing levels of Pb exposure stress. Transmission electron microscopy (TEM) showed that Pb accumulates in the inactive metabolic regions (cell walls and vesicles) in roots and stems, which may be the main mechanism for plants to reduce Pb biotoxicity. Fourier transform infrared spectroscopy (FTIR) showed that Pb stress increased the content of intracellular -OH and -COOH functional groups. Through organic acids, polysaccharides, proteins and other compounds bound to Pb, the adaptation and tolerance of K. paniculata to Pb were enhanced. K. paniculata showed good phytoremediation potential and has broad application prospects for heavy metal-contaminated soil.
作者机构：
[谢天志; 陈永华; 苏荣葵; 刘慧; 姚海松] College of Environmental Science and Engineering, Central South University of Forestry and Technology, Changsha;430003, China;[谢天志; 陈永华; 苏荣葵; 刘慧; 姚海松] 430003, China
期刊：
Journal of Environmental Management,2021年294:113029 ISSN：0301-4797
通讯作者：
Yonghua Chen<&wdkj&>Lu Du
作者机构：
[Du, Lu; He, Langjun; Chen, Yonghua; Cai, Bin] Cent South Univ Forestry & Technol, Coll Environm Sci & Engn, Changsha 410004, Peoples R China.;[Liu, Zhiming] Eastern New Mexico Univ, Dept Biol, Portales, NM 88130 USA.
通讯机构：
[Yonghua Chen; Lu Du] C;College of Environmental Science and Engineering, Central South University of Forestry and Technology, Changsha, 410004, China
关键词：
Antioxidant enzymes;Heavy metal stress;Macleaya cordata;Soil amendments;Subcellular distribution
摘要：
Phytoremediation is an essential technique for mines' ecological restoration. Modifiers addition can alleviate the stress of heavy metals to plants and enhanced remediation efficiency. Herein, spent mushroom compost (SMC) and calcium carbonate (CaCO(3)) were added to lead-zinc mine tailings to reveal the mechanism of Macleaya cordata adaptive to heavy metals stress. Pot experiments were conducted in 100% tailing (T), 90% tailing+5% SMC+5% CaCO(3) (T+), and 100% natural soil (NS). The results indicate that SMC and CaCO(3) amendments could improve the structure and fertility of tailings, and promote the growth of M. cordata, increase the content of heavy metals accumulated in plants, enhance the synthesis of chlorophyll and increas the content of soluble protein in leaves; enhance the activities of antioxidase, that can protectcelluar components from oxidative damage. Moreover, most of Pb, Zn, and Cd existed in the cell wall and soluble components, adding SMC and CaCO(3) could promote the conversion of Pb, Zn, and Cd to chemical forms with less toxicity and migratory capability. The results of transmission electron microscopy (TEM) and Fourier transform infrared spectrometer (FTIR) showed that SMC and CaCO(3) could protect the structural integrity of cells and increase the contents of -OH, -COOH functional groups that can bind to heavy metals in cells. The addition of SMC and CaCO(3) can alleviate the stress of heavy metals on M. cordata, enhancing its adaptability to heavy metals and phytoremediation capacity.
摘要：
The contamination of toxic heavy metals was a major issue of concern in the last century. A fast-growing metal-accumulating woody plant is a promising approach for the remediation of toxic heavy metal. In this study, the transportation of heavy metals (Pb, Zn, Cu, and Cd) in Paulownia fortunei cultivated in lead-zinc slag amended with different mass ratios of peat (CK: 0; T1: 10%; T2: 20%; T3: 30%) was investigated, as well as the subcellular distribution of Pb, Zn, Cu, and Cd in Paulownia fortunei. The results showed that the accumulation content of Pb, Zn, Cu, and Cd in Paulownia fortunei were increased with peat amendment, which was in the range of 4.216 similar to 6.853, 20.905 similar to 23.017, 1.898 similar to 2.572, and 0.530 similar to 0.616 mg/pot, respectivly. The experimental group with 30% dose of peat showed the best performance on the accumulation content of Pb, Zn, Cu, and Cd, with increase rates (compared to control) of 4.088, 10.573, 1.360, and 0.294 mg/pot, respectively. The bioconcentration, translocation and transfer quantity factor of Pb, Zn, Cu, and Cd were less than 1. Fixation of cell wall and compartmentalization of vacuolar appeared to play an important role in reducing the toxicity of Pb, Zn, Cu, and Cd.
