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Degradation of permeability resistance of high strength concrete after combustion

LI Min, QIAN Chunxiang, KAO Hongtao

《结构与土木工程前沿(英文)》 2008年 第2卷 第3期   页码 281-287 doi: 10.1007/s11709-008-0031-9

摘要: To evaluate the remaining durability of concrete materials after combustion, the permeability of high strength concrete (HSC) after combustion was studied. The transport behavior of chloride ion, water and air in concrete after combustion and the effect of temperature, strength grade, and aggregation on the permeability of HSC after combustion are investigated by chloride ion permeability coefficient (), water permeability coefficient () and air permeability coefficient (). The experiment results show that all three permeability coefficients commendably reflect changes of permeability. The permeability coefficient increases with the evaluation temperature. After the same temperature, the permeability coefficient of HSC is lower than that of normal strength concrete (NSC). However, the degree of degradation of permeability coefficient of HSC is greater than that of NSC. The permeability resistance of HSC containing limestone is better than that of HSC containing basalt. Combining changes of compressive strength and permeability, the remaining durability of concrete materials after combustion is appropriately evaluated.

关键词: transport behavior     limestone     durability     permeability     HSC    

Effect of eccentricity in reinforced concrete beam-column-slab connection under cyclic loading

Rooh ULLAH, Amjad NASEER, Muhammad FAHIM, Mohammad ASHRAF, Eid BADSHAH

《结构与土木工程前沿(英文)》 2021年 第15卷 第2期   页码 390-398 doi: 10.1007/s11709-021-0690-3

摘要: Beam–column connections are one of the most critical elements of reinforced concrete structures, especially in seismically active regions, and have been extensively evaluated experimentally and numerically. However, very limited experimental studies about eccentric reinforced concrete connections including the effect of connected slabs are available. This study presents the experimental results of two half-scale eccentric beam-column-slab connections subjected to quasi-static cyclic loading. The horizontal eccentricity ( ) is maintained at 12.5% and 25% of column width ( ) for specimens 1 and 2, respectively. The damage pattern, performance levels, displacement ductility ( ), energy dissipation, and connection strength and stiffness are compared for both specimens, and the effect of eccentricity is evaluated. It is concluded that the eccentricity has no significant effect on the lateral load carrying capacity; however, the overall strength degradation increases with the increase in eccentricity. Similarly, the elastic stiffness of specimen 2 decreased by 14% as the eccentricity increased from 12.5% to 25%; however, the eccentricity had no significant effect on the overall stiffness degradation. decreased by 43%, and the energy dissipation capacity decreased by 40% in specimen 2 with higher eccentricity. The story drifts corresponding to the performance levels of the life safety (LS) and collapse prevention (CP) were found to be 28% lesser in specimen 2 than in specimen 1.

关键词: corner connection     eccentricity     strength degradation     stiffness degradation     energy dissipation     performance levels    

Influence of construction-induced damage on the degradation of freeze–thawed lightweight cellular concrete

《结构与土木工程前沿(英文)》 2021年 第15卷 第3期   页码 781-792 doi: 10.1007/s11709-021-0733-9

摘要: During the construction of lightweight cellular concrete (LCC), material damage frequently occurs, causing the degradation and deterioration of the mechanical performance, durability, and subgrade quality of LCC. The construction-induced damage can be more significant than those from the service environment of LCC, such as freeze–thaw (F–T) action in cold regions. However, the effect of construction-induced damage on LCC during F–T cycles is often ignored and the deterioration mechanisms are not yet clarified. In this study, we investigated the factors causing damage during construction using a sample preparation method established to simulate the damage in the laboratory setting. We conducted F–T cycle tests and microstructural characterization to study the effect of microstructural damage on the overall strength of LCC with different water contents under F–T actions. We established the relationship between the pore-area ratio and F–T cycle times, pore-area ratio, and strength, as well as the F–T cycle times and strength under different damage forms. The damage evolution is provided with the rationality of the damage equation, verified by comparing the measured and predicted damage variables. This study would serve as a guide for the construction and performance of LCC in cold regions.

关键词: lightweight cellular concrete     construction-induced damage     freeze-thaw action     microstructure     degradation mechanism    

Efficient degradation of orange II by ZnMn

Qingzhuo Ni, Hao Cheng, Jianfeng Ma, Yong Kong, Sridhar Komarneni

《化学科学与工程前沿(英文)》 2020年 第14卷 第6期   页码 956-966 doi: 10.1007/s11705-019-1907-z

摘要: A ZnMn O catalyst has been synthesized via a sucrose-aided combustion method and characterized by various analytical techniques. It is composed of numerous nanoparticles (15–110 nm) assembled into a porous structure with a specific surface area (SSA) of 19.1 m ·g . Its catalytic activity has been investigated for the degradation of orange II dye using three different systems, i.e., the photocatalysis system with visible light, the chemocatalysis system with bisulfite, and the photo-chemical catalysis system with both visible light and bisulfite. The last system exhibits the maximum degradation efficiency of 90%, much higher than the photocatalysis system (15%) and the chemocatalysis system (67%). The recycling experiments indicate that the ZnMn O catalyst has high stability and reusability and is thus a green and eximious catalyst. Furthermore, the potential degradation mechanisms applicable to the three systems are discussed with relevant theoretical analysis and scavenging experiments for radicals. The active species such as Mn(III), O , h , e , SO and HO are proposed to be responsible for the excellent degradation results in the photo-chemical catalysis system with the ZnMn O catalyst.

关键词: ZnMn2O4     photo-chemical catalysis     bisulfite     dye degradation    

Promotive effect of pyridine on indole degradation by activated sludge under anoxic conditions

LI Yongmei, GU Guowei, LI Wenshu

《环境科学与工程前沿(英文)》 2007年 第1卷 第4期   页码 493-497 doi: 10.1007/s11783-007-0079-0

摘要: Batch experiments were carried out to investigate the promotive effect of pyridine on indole degradation under denitrifying conditions. The seed sludge was obtained from a local coal-coking wastewater treatment facility and was acc

关键词: wastewater treatment     coal-coking wastewater     promotive     degradation    

anchored alginate/poly(acrylic acid/acrylamide) double-network hydrogel composites for efficient catalytic degradation

《化学科学与工程前沿(英文)》 2023年 第17卷 第7期   页码 893-905 doi: 10.1007/s11705-022-2290-8

摘要: A novel alginate/poly(acrylic acid/acrylamide) double-network hydrogel composite with silver nanoparticles was successfully fabricated using the sol–gel method. The presence of carboxyl and amide groups in the network structure provided abundant active sites for complexing silver ions, facilitating the in situ reduction and confinement of silver nanoparticles. In batch experiments, the optimal silver loading was 20%, and 5 mmol·L–1 of p-nitrophenol was completely degraded in 113 s with a rate constant value of 4.057 × 10−2 s–1. In the tap water system and simulated seawater system, the degradation time of p-nitrophenol at the same concentration was 261 and 276 s, respectively, with a conversion rate above 99%. In the fixed-bed experiment, the conversion rate remained above 74% after 3 h at a flowing rate of 7 mL·min–1. After 8 cycling tests, the conversion rate remained at 98.7%. Moreover, the catalyst exhibited outstanding performance in the degradation experiment of four typical organic dyes.

关键词: double-network hydrogel     dye degradation     silver nanoparticles     alginate    

Sustainable wood-based nanotechnologies for photocatalytic degradation of organic contaminants in aquatic

《环境科学与工程前沿(英文)》 2021年 第15卷 第4期 doi: 10.1007/s11783-020-1346-6

摘要:

•Wood and its reassemblies are ideal substrates to develop novel photocatalysts.

关键词: Wood     Nanocatalysts     Photodegradation     Organic contaminants     Composites    

Thermal degradation kinetics and lifetime estimation for polycarbonate/polymethylphenylsilsesquioxane

Jiangbo WANG, Zhong XIN

《化学科学与工程前沿(英文)》 2009年 第3卷 第2期   页码 167-171 doi: 10.1007/s11705-009-0006-y

摘要: The thermal degradation behaviors of polycarbonate/polymethylphenylsilsesquioxane (FRPC) composites were investigated by thermogravimetric analysis (TGA) under isothermal conditions in nitrogen atmosphere. The isothermal kinetics equation was used to describe the thermal degradation process. The results showed that activation energy ( ), in the case of isothermal degradation, was a quick increasing function of conversion (α) for polycarbonate (PC) but was a strong and decreasing function of conversion for FRPC. Under the isothermal condition, the addition of polymethylphenylsilsesquioxane (PMPSQ) retardanted the thermal degradation and enhanced the thermal stability of PC during the early and middle stages of thermal degradation. It also indicated a possible existence of a difference in nucleation, nuclei growth, and gas diffusion mechanism in the thermal degradation process between PC and FRPC. Meanwhile, the addition of PMPSQ influenced the lifetime of PC, but the composite still met the demand in manufacturing and application.

关键词: polycarbonate     polymethylphenylsilsesquioxane     thermal degradation kinetics     activation energy     lifetime    

Evaluating the material strength from fracture angle under uniaxial loading

Jitang FAN

《结构与土木工程前沿(英文)》 2019年 第13卷 第2期   页码 288-293 doi: 10.1007/s11709-018-0480-8

摘要: The most common experimental methods of measuring material strength are the uniaxial compressive and tensile tests. Generally, shearing fracture model occurs in both the tests. Compressive strength is higher than tensile strength for a material. Shearing fracture angle is smaller than 45° under uniaxial compression and greater than 45° under uniaxial tension. In this work, a unified relation of material strength under uniaxial compression and tension is developed by correlating the shearing fracture angle in theory. This constitutive relation is quantitatively illustrated by a function for analyzing the material strength from shear fracture angle. A computational simulation is conducted to validate this theoretical function. It is full of interest to give a scientific illustration for designing the high-strength materials and engineering structures.

关键词: strength     fracture     mechanics    

bismuth oxyiodide with highly exposed (110) facets on curved carbon nitride for the photocatalytic degradation

《化学科学与工程前沿(英文)》 2022年 第16卷 第7期   页码 1125-1138 doi: 10.1007/s11705-021-2116-0

摘要: Crystalline materials with specific facet atomic arrangements and crystal facet structures exhibit unique functions according to their facet effects, quantum size effects and physical and chemical properties. In this study, a novel high-exposure (110) facet of bismuth oxyiodide (BiOI) was prepared (denoted as BiOI-110), and designed as nanosheets rich in oxygen vacancies by crystal facet design and regulation. Graphitic carbon nitride was designed as curved carbon nitride with dibromopyrazine, denoted as DCN, which contributed to a significant structural distortion in plane symmetry and improved the separation of charge carriers. Novel heterostructured BiOI-110/DCN nanosheets with a high-exposure (110) facet and abundant oxygen vacancies were successfully designed to enhance the photocatalytic degradation of organic pollutants. It was demonstrated that complete and tight contact between BiOI-110 and DCN was achieved by changing the size and crystal facet of BiOI. Oxytetracycline (OTC) and methyl blue dyes were used as targets for pollutant degradation, and 85.6% and 96.5% photocatalytic degradation efficiencies, respectively, were observed in the optimal proportion of 7% BiOI-110/DCN. The experimental results and electron spin resonance analysis showed that •O2 and h+ played a major role in the process of pollutant degradation. Additionally, high-resolution liquid chromatography-mass spectrography was used to identify the reaction intermediates of OTC, and the possible degradation pathway of this pollutant was proposed. Finally, the excellent reusability of BiOI-110/DCN nanomaterials was confirmed, providing a new approach for the removal of antibiotics that are difficult to biodegrade. Overall, crystal facet design has been proven to have broad prospects in improving the water environment.

关键词: high-exposure (110) facet     oxygen vacancy-rich     BiOI-110/DCN heterojunction     photocatalytic degradation     visible-light-response    

UV-LED/P25-based photocatalysis for effective degradation of isothiazolone biocide

《环境科学与工程前沿(英文)》 2021年 第15卷 第5期 doi: 10.1007/s11783-020-1379-x

摘要:

• UV-LED with shorter wavelength was beneficial for photocatalytic degradation.

关键词: Degradation     Photocatalytic     LED     CMIT     P25    

Mechanistic insights into the selective photocatalytic degradation of dyes over TiO/ZSM-11

《环境科学与工程前沿(英文)》 2023年 第17卷 第8期 doi: 10.1007/s11783-023-1701-5

摘要:

● TiO2/ZSM-11 was prepared by a facile solid state dispersion method.

关键词: Selective dye degradation     Photocatalysis     TiO2     ZSM-11     Chemisorption    

Photocatalytic degradation of methyl orange using ZnO/TiO composites

Ming GE , Changsheng GUO , Xingwang ZHU , Lili MA , Wei HU , Yuqiu WANG , Zhenan HAN ,

《环境科学与工程前沿(英文)》 2009年 第3卷 第3期   页码 271-280 doi: 10.1007/s11783-009-0035-2

摘要: ZnO/TiO composites were synthesized by using the solvothermal method and ultrasonic precipitation followed by heat treatment in order to investigate their photocatalytic degradation of methyl orange (MO) in aqueous suspension under UV irradiation. The composition and surface structure of the catalyst were characterized by X-ray diffraction (XRD), field emission scanning electron microscope (FE-SEM), and transmission electron microscopy (TEM). The degradation efficiencies of MO at various pH values were obtained. The highest degradation efficiencies were obtained before 30min and after 60min at pH 11.0 and pH 2.0, respectively. A sample analysis was conducted using liquid chromatography coupled with electrospray ionization ion-trap mass spectrometry. Six intermediates were found during the photocatalytic degradation process of quinonoid MO. The degradation pathway of quinonoid MO was also proposed.

关键词: photocatalytic degradation     methyl orange     ZnO/TiO2 composites     high performance liquid chromatography mass spectrometry (HPLC-MS)    

Acid Orange 7 degradation using methane as the sole carbon source and electron donor

《环境科学与工程前沿(英文)》 2022年 第16卷 第3期 doi: 10.1007/s11783-021-1468-5

摘要:

• AO7 degradation was coupled with anaerobic methane oxidation.

关键词: Azo dyes     AO7 degradation     Anaerobic methane oxidation     Microbial community     ANME-2d    

Photocatalytic degradation of polybrominated diphenyl ethers in pure water system

Min ZHANG,Jian LU,Yiliang HE,P Chris WILSON

《环境科学与工程前沿(英文)》 2016年 第10卷 第2期   页码 229-235 doi: 10.1007/s11783-014-0762-x

摘要: Due to the low water solubility of polybrominated diphenyl ethers, organic solvent is usually added into the oxidation system to enhance the removal efficiency. In this study the photocatalytic degradation of decabromodiphenyl ether (BDE209), a type of polybrominated diphenyl ether used throughout the world, in pure water without the addition of organic solvent was investigated. In the pure water system, BDE209 was not dissolved but dispersed as nano-scale particles with a mean diameter of 166 nm. Most of BDE209 (>98%) were removed within 4 h and the final debromination ratio was greater than 80%. Although the addition of organic solvent (tetrahydrofuran, THF) could lead to a relatively high BDE209 degradation rate, the final debromination ratio (<50%) was much lower than that in pure water system. Major oxidation intermediates of tetrahydrofuran, including tetrahydro-2-furanol and γ-butyrolactone, were detected indicating the engagement of THF in the BDE209 degradation process. The photocatalytic degradation of BDE209 in the pure water system followed first-order kinetics. The BDE209 degradation rate constant increased from 0.0011 to 0.0023 min as the pH increased from 3 to 9.

关键词: polybrominated diphenyl ethers     photocatalytic degradation     solvent    

标题 作者 时间 类型 操作

Degradation of permeability resistance of high strength concrete after combustion

LI Min, QIAN Chunxiang, KAO Hongtao

期刊论文

Effect of eccentricity in reinforced concrete beam-column-slab connection under cyclic loading

Rooh ULLAH, Amjad NASEER, Muhammad FAHIM, Mohammad ASHRAF, Eid BADSHAH

期刊论文

Influence of construction-induced damage on the degradation of freeze–thawed lightweight cellular concrete

期刊论文

Efficient degradation of orange II by ZnMn

Qingzhuo Ni, Hao Cheng, Jianfeng Ma, Yong Kong, Sridhar Komarneni

期刊论文

Promotive effect of pyridine on indole degradation by activated sludge under anoxic conditions

LI Yongmei, GU Guowei, LI Wenshu

期刊论文

anchored alginate/poly(acrylic acid/acrylamide) double-network hydrogel composites for efficient catalytic degradation

期刊论文

Sustainable wood-based nanotechnologies for photocatalytic degradation of organic contaminants in aquatic

期刊论文

Thermal degradation kinetics and lifetime estimation for polycarbonate/polymethylphenylsilsesquioxane

Jiangbo WANG, Zhong XIN

期刊论文

Evaluating the material strength from fracture angle under uniaxial loading

Jitang FAN

期刊论文

bismuth oxyiodide with highly exposed (110) facets on curved carbon nitride for the photocatalytic degradation

期刊论文

UV-LED/P25-based photocatalysis for effective degradation of isothiazolone biocide

期刊论文

Mechanistic insights into the selective photocatalytic degradation of dyes over TiO/ZSM-11

期刊论文

Photocatalytic degradation of methyl orange using ZnO/TiO composites

Ming GE , Changsheng GUO , Xingwang ZHU , Lili MA , Wei HU , Yuqiu WANG , Zhenan HAN ,

期刊论文

Acid Orange 7 degradation using methane as the sole carbon source and electron donor

期刊论文

Photocatalytic degradation of polybrominated diphenyl ethers in pure water system

Min ZHANG,Jian LU,Yiliang HE,P Chris WILSON

期刊论文