摘要：
The simultaneous electro-oxidation of Ni (II)-citrate and electrodeposition recovery of nickel metal were attempted in a combined electro-oxidation-electrodeposition reactor with a boron-doped diamond (BDD) anode and a polished titanium cathode. Effects of initial nickel citrate concentration, current density, initial pH, electrode spacing, electrolyte type, and initial electrolyte dosage on electrochemical performance were examined. The efficiencies of Ni (II)-citrate removal and nickel metal recovery were determined to be 100% and over 72%, respectively, under the optimized conditions (10 mA/cm(2), pH 4.09, 80 mmol/L Na2SO4, initial Ni (II)-citrate concentration of 75 mg/L, electrode spacing of 1 cm, and 180 min of electrolysis). Energy consumption increased with increased current density, and the energy consumption was 0.032 kWh/L at a current density of 10 mA/cm(2) (pH 6.58). The deposits at the cathode were characterized by scanning electron microscopy (SEM), energy-dispersive spectrometry (EDS), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). These characterization results indicated that the purity of metallic nickel in cathodic deposition was over 95%. The electrochemical system exhibited a prospective approach to oxidize metal complexes and recover metallic nickel. (C) 2022 The Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences. Published by Elsevier B.V.
期刊：
Journal of Building Engineering,2022年62:105375 ISSN：2352-7102
通讯作者：
Dong Xie
作者机构：
[Wang, Chenhua; Liu, Junjie] Tianjin Univ, Sch Environm Sci & Engn, Tianjin Key Lab Indoor Air Environm Qual Control, Tianjin, Peoples R China.;[Wang, Chenhua; Xie, Dong; Yu, Chuck Wah] Univ South China, Sch Civil Engn, Natl & Local Joint Engn Res Ctr Airborne Pollutant, Hengyang, Peoples R China.
通讯机构：
[Dong Xie] N;National & Local Joint Engineering Research Center for Airborne Pollutants Control and Radioactivity Protection in Buildings, School of Civil Engineering, University of South China, Hengyang, China
摘要：
To reduce hazards due to the radon dispersion on occupants, careful consideration of multi -parameters of stratum ventilation is necessary, including air supply velocity, temperature, angle and air outlet position. In this study, the radon dispersion in a typical office with stratum ventilation was evaluated based on experimental measurements and computational fluid dy-namics (CFD) modelling. Besides, the ventilation performance of each scheme was evaluated by using a technique of order preference by similarity to the ideal solution (TOPSIS) method. Results showed that the mentioned factors and their interactions could pose important impacts on the indoor environment. Combining with TOPSIS, the optimal operation of the stratum ventilation was determined. Compared with the worst ventilation scheme, the ventilation effectiveness was increased by 77.4%, the air distribution performance index (ADPI) was increased by 38.1% and the radon radiological effective dose rate was reduced by 63.4%. The findings may form an important mitigation control strategy to effectively minimize radioactive exposure in indoor environments.
摘要：
The reduction of soluble U(VI) to insoluble U(IV) by photocatalytic technology is considered to be a valid method to remove U(VI) from aqueous. Herein, g-C3N4/Ag/TiO2 Z-scheme heterojunction was synthesized for photocatalytic U(VI) reduction application. The SEM, XRD and XPS characterization results showed that the ternary g-C3N4/Ag/TiO2 composite photocatalyst was synthesized successfully. g-C3N4/Ag/TiO2 exhibited excellent photocatalytic reduction performance for U(VI) under visible light irradiation. After 30 min irradiation, the removal rate of U(VI) was above 99%. XPS indicated that the majority of U(VI) on the surface of g-C3N4/Ag/TiO2 was reduced to U(IV). In addition, the photocatalytic activity of g-C3N4/Ag/TiO2 has been kept significantly after five rounds of experiments, indicating the good stability. g-C3N4/Ag/TiO2 exhibited better photocatalytic reduction of U(VI) under visible light irradiation, which is mainly ascribed to Z-scheme photocatalytic mechanism assisted by the LSPR effect (Local Surface Plasmon Resonance). Ag with plasmon resonance effect on the loading has a strong absorption of photon energy. In addition, an intermediate charge transfer channel is formed between Ag and the semiconductor to inhibit the combination of photogenerated electrons and holes, resulting in a significant increase in the photocatalytic activity of the photocatalyst. This idea has some significance in design of other composite photocatalytic system.
期刊：
Construction and Building Materials,2022年343:127953 ISSN：0950-0618
通讯作者：
Tao, Qiuwang(taoqiuwang@usc.edu.cn)
作者机构：
[Deng, Du; Li, Zhujing; Chen, Zhenfu; Tao, Qiuwang; Jin, Dan; Luo, Lincheng] Univ South China, Sch Civil Engn, Hengyang 421001, Hunan, Peoples R China.;[Deng, Du; Chen, Zhenfu; Tao, Qiuwang; Luo, Lincheng] Univ South China, China Nucl Ind Key Lab High Performance Concrete, Hengyang 421001, Hunan, Peoples R China.;[Deng, Du; Li, Zhujing; Chen, Zhenfu; Tao, Qiuwang; Jin, Dan; Luo, Lincheng] Univ South China, Hunan Prov Key Lab High Performance Special Concre, Hengyang 421001, Hunan, Peoples R China.;[Xie, Liping] China Nucl Ind 22ND Construct Co Ltd, Yichang 443101, Hubei, Peoples R China.
通讯机构：
[Qiuwang Tao] S;School of Civil Engineering, University of South China, Hengyang 421001, Hunan Province, China<&wdkj&>China Nuclear Industry Key Laboratory of High-Performance Concrete, University of South China, Hengyang 421001, Hunan Province, China<&wdkj&>Hunan Provincial Key Laboratory of High-Performance Special Concrete, University of South China, Hengyang 421001, Hunan Province, China
关键词：
Barite;Gamma ray shielding;High temperature;Magnetite;Radiation shielding concrete;Splitting tensile strength
通讯机构：
[Qiongfang Zhuo; Junfeng Niu] S;School of Environment and Civil Engineering, Research Center for Eco-environmental Engineering, Dongguan University of Technology, Dongguan 523808, China
摘要：
In this study, TiO2 nanotube arrays (TiO2-NTA) were used as an intermediate layer to provide effective electrocatalytic activity and stability for Ti/TiO2-NTA/Ti4O7 anode. Compared with Ti/Ti4O7 anode, Ti/TiO2-NTA/ Ti4O7 anode exhibited higher oxygen evolution potential (2.40 V), larger active specific surface areas (1.81 m(2) g(-1)), stronger radical generation capacity (64.42 mu M), longer accelerated service life (56.0 h), and superior favipiravir removal ratio. The flow-through electrochemical reaction system was constructed by using the porous Ti/TiO2-NTA/Ti4O7 anode. The removal ratio, TOC removal ratio and mineralization current efficiency of favipiravir in the flow-by electrochemical system were significantly improved and the energy consumption was reduced compared with the conventional flow-by electrochemical system, verifying the superiority of the porous flow-through Ti/TiO2-NTA/Ti4O7 anode. The effects of operating parameters on the removal of favipiravir in the flow-through electrochemical reaction system were investigated. The degradation mechanisms of favipiravir are the synergetic effects of the free radical (.OH and SO4 center dot-) and the direct electron transfer. Ti/TiO2-NTA/Ti4O7 anode displayed excellent stability in five consecutive cycles, exhibited significant removal ratio (87.7%) of favipiravir from actual wastewater, and remained efficient and versatile for a wide range of typical PPCPs pollutants. Therefore, Ti/TiO2-NTA/Ti4O7 is a promising porous anode material in the engineering application.
作者机构：
[Xie, Dong; Xiao, Peilin] Univ South China, Sch Resource Environm & Safety Engn, Hengyang 421001, Peoples R China.;[Xie, Dong; Sang, Lixin; Cai, Ninghua; Dou, Xiumin] Univ South China, Sch Civil Engn, Hengyang 421001, Peoples R China.;[Xie, Dong; Wang, Hanqing; Xiao, Peilin; Sang, Lixin; Cai, Ninghua; Dou, Xiumin] Natl & Local Joint Engn Res Ctr Airborne Pollutant, Hengyang 421001, Peoples R China.;[Wang, Hanqing] Cent South Univ Forestry & Technol, Sch Civil Engn, Changsha 410000, Peoples R China.
通讯机构：
[Ninghua Cai] S;School of Civil Engineering, University of South China, Hengyang 421001, China<&wdkj&>National & Local Joint Engineering Research Center for Airborne Pollutants Control and Radioactivity Protection in Buildings, Hengyang 421001, China<&wdkj&>Author to whom correspondence should be addressed.
关键词：
wind tunnel experiment;atmospheric boundary layer;spire;rough element;field test
摘要：
To investigate the pollutant dispersion of a nuclear power plant, a field tracing experiment was carried out in neutral stratification weather with the main wind direction SSW. On this basis, a wind speed profile and turbulence intensity profile consistent with the site were created in the wind tunnel. Meanwhile, how to generate a wind field of neutral stratification in a wind tunnel was studied in detail. Finally, a 1:1000 nuclear power area model was made to conduct tracing experiments in the wind tunnel. The results show that when the horizontal and vertical distances of the spire are 300 mm and 500 mm, and the horizontal and vertical distances of the rough element are 250 mm and 500 mm. A wind speed profile with a wind profile index of 0.321 was generated in the wind tunnel (0.334 in the field test), and the wind tunnel tracer experiment had the same diffusion trend as the field, which verified the accuracy of the flow field.
摘要：
The development of eco-friendly and efficient alternative binder to conventional Portland cement is a challenging issue that deserves to be paid more attention. The mineral additive-modified magnesium potassium phosphate cement mixture was introduced in sediment solidification recycled as alternative roadbed material. The feasibility of mineral additive-MKPC blend in solidifying sediment and its mechanical performance were probed into deeply through unconfined compressive strength, durability, microstructural and mineralogical tests. The results demonstrated that it existed an optimal mineral additive content where the peak strength was achieved, and an excessive amount caused the strength degradation. The unconfined compressive strength of solidified sediment increased with curing age and exhibited a growing potential. Struvite-k crystals were identified as the major cementing phase in mineral additive-MKPC solidified sediment. C-S-H gels and Ca2P2O7 c 2H2O were recognized as secondary phases for fly ash-MKPC blend and MgSiO3 for silica fume-MKPC blend. As the molar ratio of M/P and curing age grew, the total porosity was reduced due to the pore filling of mineral grains and densification of hydrated phases. The strength of solidified sediment after durability tests showed a tendency of first decline and then increase with durability period. Overall, the superior benefits including excellent strength performance, strong resistance to external environmental damage and highly densified microstructure could be expected for mineral additive-MKPC blend in sediment solidification as a promising roadbed filling.
作者机构：
[Zhang, Xiaoling; Wang, Liangqin; Liu, Yingjiu; Liu, Jinxiang; Zeng, Taotao; Wang, Guohua] Univ South China, Hunan Prov Key Lab Pollut Control & Resources Reu, Hengyang 421001, Peoples R China.;[Wang, Aijie] Chinese Acad Sci, Key Lab Environm Biotechnol, Beijing 100085, Peoples R China.
通讯机构：
[Taotao Zeng] H;Hunan Province Key Laboratory of Pollution Control and Resources Reuse Technology, University of South China, Hengyang, 421001, China
摘要：
In this study, a complex bacterial consortium was enriched from a typical Pb-Zn mine area and immobilized by sodium alginate to form biospheres, which were used for treatment of selenite (Se(IV))- and cadmium (Cd(II))-containing wastewater without external carbon source. Batch experiments showed that the maximum Se(IV) removal efficiency was 92.36% under the optimal conditions of an initial pH of 5, dosage of 5g/L, initial Se(IV) concentration of 7.9mg/L and reaction time of 168h. Subsequently, more than 99% of 11.2mg/L Cd(II) was removed by the biospheres within 10h. Physicochemical characterization showed that reduction and adsorption were the main mechanisms for Se(IV) and Cd(II) removal, respectively. During the removal process, selenium and CdSe nanoparticles were formed. Bacterial community analysis showed the dominant bacterial genera changed after treatment of Se(IV)- and Cd(II)-containing wastewater. Additionally, 16S rRNA gene function prediction results showed that amino acid transport, carbohydrate transport, ion transport and metabolism were the dominant gene functions. The present study provides a potential way for the biological treatment of Se(IV)- and Cd(II)-containing wastewater using immobilized biospheres without external carbon source in short-term.
关键词：
Rock mechanics;Jointed rock;Crack propagation;Uniaxial compression;Particle flow theory
摘要：
The existence of joints has a significant influence on the failure characteristics of rock mass. In this paper, based on two-dimensional (2D) particle flow code (PFC2D), uniaxial compression tests are conducted on the granite specimens with a single joint at different dip angles to investigate the evolution laws of macroscopic and mesoscopic failure characteristics. The results demonstrate that macro-mechanical characteristics of rock are influenced by the dip angle of the joint. The peak strength, peak deformation, and elastic modulus are positively correlated with the dip angle of the joint, while Poisson's ratio is negatively correlated. With the increase in the dip angle of the joint, mechanical characteristics of rock finally tend to be consistent with those of an intact rock specimen. In addition, when the dip angle of the joint is small, the rock specimens show obvious plastic characteristics before reaching the peak and there are multiple peaks being found on stress-strain curves. As the dip angle of the joint rises, the number of stress fluctuations gradually decreases and the curve near the peak becomes straighter and sharper. Moreover, the rock specimens exhibit more obvious brittle characteristics. The increase in the dip angle of the joint enhances the tendency of azimuth angle of microcracks to develop along the direction of the maximum principal stress. In the meanwhile, the distribution of the azimuth angle is gradually similar to that of microcracks in the intact specimen. With the rise of the joint dip angle, the failure modes of rock specimens change from tensile failure to shear failure to tensile failure, and finally tend to be consistent with the intact rock.
作者机构：
[Zhou, Shuai; Duan, Yi] Univ South China, Hunan Prov Key Lab Pollut Control & Resources Reu, Hengyang 421001, Peoples R China.;[Liu, Boyang; Zhou, Shuai; Duan, Yi; Xiong, Cong] Univ South China, Sch Civil Engn, Hengyang 421001, Peoples R China.;[Gao, Yuanyuan; Zhou, Shuai; Tang, Zhenping] Univ South China, Hunan Prov Key Lab Rare Met Minerals Exploitat &, Hengyang 421001, Peoples R China.;[Su, Yinglong] East China Normal Univ, Sch Ecol & Environm Sci, Shanghai 200241, Peoples R China.;[Wang, Yayi] Tongji Univ, Coll Environm Sci & Engn, Shanghai Inst Pollut Control & Ecol Secur, State Key Lab Pollut Control & Resources Reuse, Siping Rd, Shanghai 200092, Peoples R China.
通讯机构：
[Yi Duan] H;Hunan Province Key Laboratory of Pollution Control and Resources Reuse Technology, University of South China, Hengyang, 421001, China<&wdkj&>School of Civil Engineering, University of South China, Hengyang, 421001, China
作者机构：
[Guo, Xinxun; Guo, Yongli; Fang, Yaochu; Zhang, Wenlong; Wu, Wentao; Luo, Yaoge; Sun, Bing] Univ South China, Sch Civil Engn, Hengyang 421001, Hunan, Peoples R China.;[Fang, Yaochu; Sun, Bing] Hunan Prov Key Lab High Performance Special Concre, Hengyang 421001, Hunan, Peoples R China.;[Fang, Yaochu; Sun, Bing] China Nucl Construction Key Lab High Performance C, Hengyang 421001, Hunan, Peoples R China.;[Wu, Wentao] JZFZ Architectural Design Co LTD, Xian Branch Chengdu, Xian 710000, Peoples R China.;[Zhu, Xiang] Shanxi Univ, Sch Elect Power, Civil Engn & Architecture, Taiyuan 030013, Shanxi, Peoples R China.
通讯机构：
[Yaochu Fang] S;School of Civil Engineering, University of South China, Hunan, Hengyang 421001, China<&wdkj&>Hunan Provincial Key Laboratory of High Performance Special Concrete, Hunan, Hengyang 421001, China<&wdkj&>China Nuclear Construction Key Laboratory of High Performance Concrete, Hunan, Hengyang 421001, China
摘要：
Based on the elastic thin plate theory, the mechanical properties and failure pattern are studied, considering the local failure defects, and the nominal positive stress expression of the hierarchical sandwich structures with a second-order core were presented. Moreover, the dominant relationship of each failure mode was compared, and the structure failure mechanism diagram is constructed by MATLAB, then the influence law of different local failure defects on the structure-dominant failure mode was discussed. However, for the failure mode of the structure, the emergence of the dominant failure mode of the secondary transmission path component may not be used as the failure criterion of the structure. Only when the failure mode of the structure appears on the main transmission path components, the failure mode can be used as the failure criterion of the hierarchical sandwich structure with a second-order core. In the failure mechanism diagram of the hierarchical sandwich structure with a second-order core, the single dominant failure mode of the structure can be accurately predicted, and for the junction of multiple mixed dominant failure modes, the structure is more prone to structural/component stability failure. At the same time, in order to test the correctness of the theoretical prediction, the verification experiment models were made with photosensitive resin 9000 material and 3D printing technology. Through the uniaxial compression test on the experimental model and numerical simulation, the correctness of the theoretical pre-diction of structural failure mode and ultimate bearing capacity is verified. The results show that the failure mode of the structure can be accurately predicted by the theoretical analysis, and the relative error is about 20% when calculating the bearing capacity. The experimental and simulation results agree well with the theoretical prediction.
作者机构：
[Huang, Chong] Chinese Acad Sci, Inst Geog Sci, State Key Lab Resources & Environm Informat Syst, Nat Resources Res, Beijing 100101, Peoples R China.;[Rong, Lishan; Xiao, Chaoliang] Univ South China, Sch Civil Engn, Hengyang 421001, Peoples R China.
通讯机构：
[Chong Huang] S;State Key Laboratory of Resources and Environmental Information System, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing 100101, China<&wdkj&>Author to whom correspondence should be addressed.
关键词：
points of interest (POIs);functional-zone identification;remote sensing;average-nearest-neighbor index;urban functional area
摘要：
Accurately identifying and delineating urban functional areas has seen increasing demand in smart urban planning, landscape design, and resource allocation. Recently, POI (point of interest) data have been increasingly applied to identify urban functional areas. However, heterogeneity in urban spaces or the corresponding POI data has not been fully considered in previous studies. In this study, we proposed a new scheme for urban-functional-area identification by combining POI data, OpenStreetMap (OSM) datasets, and high-resolution remote-sensing imagery. A function-intensity index that integrates the quantitative-density index and average-nearest-neighbor index (ANNI) of POIs was built for representing the urban function. The results show that the proposed function-intensity index can balance the impact of the spatial heterogeneity of each type of POI on determining the functional characteristics of the urban units. In Futian District, Shenzhen, China, the method was effective in distinguishing functional areas with fewer POI amounts but high ANNIs from those functional areas with dense POIs. The overall accuracy of the proposed method is about 11% higher than that of the method using the POI density only. This paper argues for considering both the quantitative density and spatial heterogeneity of POIs to improve urban-functional-area identification.
作者机构：
[Wang, Rui] NingboTech Univ, Sch Civil Engn & Architecture, Ningbo 315100, Peoples R China.;[Wang, Rui] Zhejiang Engn Res Ctr Intelligent Marine Ranch Equ, Ningbo 315100, Peoples R China.;[Wang, Jingsong; Song, Qingchun] Univ South China, Sch Civil Engn, Hengyang 421001, Peoples R China.
通讯机构：
[Rui Wang] S;School of Civil Engineering and Architecture, NingboTech University, Ningbo 315100, China<&wdkj&>Zhejiang Engineering Research Center for Intelligent Marine Ranch Equipment, Ningbo 315100, China<&wdkj&>Author to whom correspondence should be addressed.
摘要：
The purpose of study is to optimize the preparation of porous coal gangue-based geopolymer and quantitatively analyze its pore structure to establish the relationship between pore structure and mechanical properties. Porous coal gangue-based geopolymers were prepared by using coal gangue as the raw material, Na2SiO3 and NaOH as activators, H2O2 as the foaming agent and carboxymethylcellulose sodium (CMC) as the surfactant. Then response surface methodology (RSM) was used to study effects of liquid-to-solid ratio, CMC content, H2O2 content and curing temperature on compressive strength. Finally, pore number, porosity, pore size distribution and pore structure parameters were analyzed by self-developed image analysis algorithm. RSM results demonstrate that H2O2 content has the greatest effect on mechanical strength, followed by liquid-to-solid ratio, curing temperature and CMC content. Quantitative analysis of pore structure indicate that with the increase in H2O2 content, porosity could increase and pore size and pore shape could become more regular, but mechanical properties sharply deteriorate.
作者机构：
[Wang, Dongxing] Univ South China, Sch Civil Engn, Hengyang, Peoples R China.;[Wang, Dongxing] Chinese Acad Sci, Inst Rock & Soil Mech, State Key Lab Geomech & Geotech Engn, Wuhan, Peoples R China.;[Zhu, Jiaye] Wuhan Univ, Sch Civil Engn, 8 Dong Hu South Rd, Wuhan 430072, Peoples R China.;[Zeng, Gang] Hubei Univ Arts & Sci, Sch Civil Engn & Architecture, Xiangyang, Peoples R China.
通讯机构：
[Dongxing Wang] S;School of Civil Engineering, University of South China, Hengyang, China<&wdkj&>State Key Laboratory of Geomechanics and Geotechnical Engineering, Institute of Rock and Soil Mechanics, Chinese Academy of Sciences, Wuhan, China<&wdkj&>School of Civil Engineering, Wuhan University, Wuhan, China
摘要：
To ameliorate the physic-mechanical behavior of waste sludge at reasonable costs, fly ash and silica fume are incorporated in MKPC-based solidification, and the impact of MKPC-mineral additive is comprehensively examined from the multi-viewpoint of compaction, strength, permeability and compressibility. The micromorphology of solidified sludge is identified by SEM tests. The results show MKPC-mineral additive has an excellent ability to improve the strength and deformation property of sludge under the influence of MKPC content, mineral additive content, curing age and compaction degree. MKPC content and mineral additive content have a slight impact on the maximum dry density of solidified sludge. The optimum water content tends to increase with mineral additive content and to decrease with MKPC content. The compressive strength and yielding stress have an ascending trend with an extension in curing age and an increase in MKPC content and compaction degree, and the compressibility and permeability presents a descending tendency. The SEM analysis reveals that struvite-k crystals play a dominant role in cementing fine grains to form an interconnected network, and a tiny amount of Mg(OH)2 is generated as secondary phase. It should be noted C-S-H gel and MgSiO3 are respectively produced for MKPC-fly ash and MKPC-silica fume solidified sludge.
