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Study on the microwave-assisted extraction of polyphenols from tea

Liyun WANG, Peiyong QIN, Yan HU,

《化学科学与工程前沿（英文）》 2010年 第4卷 第3期   页码 307-313 doi: 10.1007/s11705-009-0282-6

摘要： This study demonstrated a promising method for quickly extracting tea polyphenol (TP) by microwave-assisted extraction (MAE) technology. Some influential parameters, including MAE temperature, microwave power, concentration of extraction solvent, MAE time and the solid/liquid ratio, were investigated. The optimum condition of MAE was obtained by dual extraction with 60% ethanol (v/v) and the solid/liquid ratio 1:12 g/mL at 80°C for 10 minutes under the microwave power 600 W. The yield of TP was 96.5% under the described condition. Compared with traditional methods, including hot reflux extraction (HRE), ultrasound-assisted extraction (UAE) and supercritical fluid extraction (SFE), the extraction time was saved 8 times than that of HRE, and the yield was increased by 17.5%. The extraction time at comparable levels of production was saved 2 times, and the energy consumption was one fourth that of UAE. The extraction time was saved 5 times than that of SFE, and the yield of TP was increased by 40%. Moreover, compared with MAE of TP studied by others, it decreased the solid/liquid ratio from 1 ∶ 20 to 1 ∶ 12 g/mL without 90-min pre-leaching time, and the yield of TP was increased by 6%–40%.

关键词： energy consumption     microwave-assisted extraction     optimum condition     pre-leaching     concentration    

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Characteristics of the stabilized/solidified municipal solid wastes incineration fly ash and the leaching

Yan SHAO,Haobo HOU,Guangxing WANG,Sha WAN,Min ZHOU

《环境科学与工程前沿（英文）》 2016年 第10卷 第1期   页码 192-200 doi: 10.1007/s11783-014-0719-0

摘要： Fly ash is a hazardous byproduct of municipal solid wastes incineration (MSWI). An alkali activated blast furnace slag-based cementitious material was used to stabilize/solidify the fly ash at experimental level. The characteristics of the stabilized/solidified fly ash, including metal leachability, mineralogical characteristics and the distributions of metals in matrices, were tested by toxic characteristic leaching procedure (TCLP), X-ray diffraction (XRD) and scanning electron microscopy-energy dispersive spectrometer (SEM-EDS) respectively. Continuous acid extraction was utilized to extract metal ions and characterize their leaching behavior. The stabilization/solidification procedure for MSWI fly ash demonstrates a strong fixing capacity for the metals by the formation of C-S-H phase, hydrated calcium aluminosilicate and ettringite. The stabilized/solidified fly ash shows a dense and homogeneous microstructure. Cr is mainly solidified in hydrated calcium aluminosilicate, C-S-H and ettringite phase through physical encapsulation, precipitation, adsorption or substitution mechanisms, and Pb is mainly solidified in C-S-H phase and absorbed in the Si-O structure.

关键词： municipal solid waste incineration (MSWI) fly ash     blast furnace slag     leaching behavior     Cr     Pb    

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Assessment of leaching behavior and human bioaccessibility of rare earth elements in typical hospital

Chunfeng Wang, Guanfei Chen, Yanchen Zhu, Dan Yao, Wanfeng Wang, Lianjun Wang

《环境科学与工程前沿（英文）》 2017年 第11卷 第6期 doi: 10.1007/s11783-017-0946-2

摘要： Leaching behavior and gastrointestinal bioaccessibility of rare earth elements (REEs) from hospital waste incineration (HWI) fly and bottom ash samples collected from Beijing and Nanjing Cities were assessed. In the same ash sample, the leaching concentrations of individual REEs determined by the Toxicity Characteristic Leaching Procedure (TCLP) were higher than those detected by the European standard protocol (EN-type test), thereby suggesting that the low pH value of leaching solution was an important factor influencing the leachability of REE. The REE bioaccessibility results, which were evaluated using the physiologically based extraction test (PBET), indicated that REEs were highly absorbed during gastric phase by dissolution; and subsequently precipitated and/or re-adsorbed in small intestinal phase. The relative amounts of the total REEs extracted by the TCLP method, EN-type test and PBET test were compared. In addition to the pH value of extraction solutions, the chelating role of REEs with organic ligands used in the PBET method was also an important parameter affecting REE adsorption in human body. Additionally, this study showed that REEs were extracted by these methods as concomitants of heavy metals and anions (NO , F , SO , and Cl ) from HWI ash, which probably caused the remarkably complex toxicity on human body by the exposure pathway.

关键词： Assessment     Rare earth elements     Leaching behavior     Bioaccessibility     Hospital waste    

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Investigation of Cu leaching from municipal solid waste incinerator bottom ash with a comprehensive approach

Jun YAO, Wenbing LI, Fangfang XIA, Jing WANG, Chengran FANG, Dongsheng SHEN

《能源前沿（英文）》 2011年 第5卷 第3期   页码 340-348 doi: 10.1007/s11708-010-0131-9

摘要： Municipal solid waste incinerator (MSWI) bottom ash is often reused as a secondary construction material. This study used a comprehensive approach to characterize the leaching behavior of copper (Cu) from the MSWI bottom ash. The batch titration procedure was used to determine the acid neutralizing capacity and Cu leaching as a function of pH. The sequential extraction procedure (SEP) was adopted to analyze the speciation of Cu in the MSWI bottom ash. The metal speciation equilibrium model for surface and ground water (Visual MINTEQ) was used to evaluate the equilibrium of the leachates with the relative minerals, and to determine the speciation of the aqueous Cu in the leachates. Based on the multi-analysis of the results, Cu would be significantly released from the MSWI bottom ash when it is acidic. The Cu leaching pattern was not only affected by dissolved organic carbon, it was also limited by its speciation in the MSWI bottom ash. Furthermore, almost 100% of the aqueous Cu in the leachate was bound to organic matter in basic and neutral conditions, but mostly existed as Cu in an acidic condition. These findings provide an important insight into predicting the leaching behavior of Cu from the MSWI bottom ash, as well as its impact on the environment.

关键词： MSWI bottom ash     Cu leaching     batch titration procedure     SEP    

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The influence of curing conditions on the mechanical properties and leaching of inorganic polymers made

Remus I. Iacobescu, Valérie Cappuyns, Tinne Geens, Lubica Kriskova, Silviana Onisei, Peter T. Jones, Yiannis Pontikes

《化学科学与工程前沿（英文）》 2017年 第11卷 第3期   页码 317-327 doi: 10.1007/s11705-017-1622-6

摘要： This study reports on the impact of the curing conditions on the mechanical properties and leaching of inorganic polymer (IP) mortars made from a water quenched fayalitic slag. Three similar IP mortars were produced by mixing together slag, aggregate and activating solution, and cured in three different environments for 28 d: a) at 20 °C and relative humidity (RH) ~ 50% (T20RH50), b) at 20 °C and RH≥90% (T20RH90) and c) at 60 °C and RH ~ 20% (T60RH20). Compressive strength (EN 196-1) varied between 19 MPa (T20RH50) and 31 MPa (T20RH90). This was found to be attributed to the cracks formed upon curing. Geochemical modelling and two leaching tests were performed, the EA NEN 7375 tank test, and the BS EN 12457-1 single batch test. Results show that Cu, Ni, Pb, Zn and As leaching occurred even at high pH, which varied between 10 and 11 in the tank test’s leachates and between 12 and 12.5 in the single batch’s leachates. Leaching values obtained were below the requirements for non-shaped materials of Flemish legislation for As, Cu and Ni in the single batch test.

关键词： inorganic polymer     geochemical leaching modelling     heavy metals     recycling     non-ferrous fayalitic slag     curing    

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Reinforcement of the two-stage leaching of laterite ores using surfactants

Peiyu Zhang, Hairui Wang, Jingcheng Hao, Jiwei Cui

《化学科学与工程前沿（英文）》 2021年 第15卷 第3期   页码 562-570 doi: 10.1007/s11705-020-1946-5

摘要： A two-stage leaching process, namely, high-pressure acid leaching-atmospheric acid leaching, was used to treat laterite ores under mild conditions. The leaching ratio of Ni was low because of adsorption and incomplete leaching. In this work, surfactants were used as additives to boost the leaching ratio of Ni. The effect of surfactant type (cationic, anionic, and nonionic surfactants) on the leaching ratio of Ni was investigated. Leaching results showed that stearyl trimethyl ammonium chloride (STAC) apparently increased the leaching ratios of valuable metals. The variation in the physicochemical properties of the lixiviant and the residue improved the leaching ratio of Ni in the presence of STAC. Kinetics analysis indicated that the leaching process was controlled by chemical reaction.

关键词： laterite ore     Ni     surfactant     acid leaching    

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Oxidative leaching kinetics of molybdenum-uranium ore in H

T. A. Lasheen, M. E. El-Ahmady, H. B. Hassib, A. S. Helal

《化学科学与工程前沿（英文）》 2013年 第7卷 第1期   页码 95-102 doi: 10.1007/s11705-013-1317-6

摘要： The processing of molybdenum-uranium ore in a sulfuric acid solution using hydrogen peroxide as an oxidant has been investigated. The leaching temperature, hydrogen peroxide concentration, sulfuric acid concentration, leaching time, particle size, liquid-to-solid ratio and agitation speed all have significant effects on the process. The optimum process operating parameters were: temperature: 95°C; H O concentration: 0.5 M; sulfuric acid concentration: 2.5 M; time: 2 h; particle size: 74 μm, liquid-to-solid ratio: 14 ∶ 1 and agitation speed: 600 rpm. Under these experimental conditions, the extraction efficiency of molybdenum was about 98.4%, and the uranium extraction efficiency was about 98.7%. The leaching kinetics of molybdenum showed that the reaction rate of the leaching process is controlled by the chemical reaction at the particle surface. The leaching process follows the kinetic model 1 ? (1? ) = with an apparent activation energy of 40.40 kJ/mole. The temperature, concentrations of H O and H SO and the mesh size are the main factors that influence the leaching rate. The reaction order in H SO was 1.0012 and in H O it was 1.2544.

关键词： leaching of molybdenum     leaching of uranium     kinetics    

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铜阳极泥预处理连续加压酸浸工艺开发研究

王吉坤,冯桂林

《中国工程科学》 2009年 第11卷 第5期   页码 18-22

摘要：

绍了新开发出来的一种具有较好工业应用前景的铜阳极泥预处理新工艺，小型及半工业试验结果表明，铜阳极泥直接加压酸浸，可以充分利用生阳极泥中水溶性铜离子的催化氧化作用，提高反应速度；在连续浸出过程中Ag，Se，Te走向与间断浸出过程差别明显，使浸出效果优于间断加压浸出预处理工艺，有利于提高有价元素的综合回收。

关键词： 铜阳极泥     综合利用     加压酸浸     连续浸出    

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Leaching of aluminum from coal spoil by mechanothermal activation

Xiaoxue SUN,Yuzhu SUN,Jianguo YU

《化学科学与工程前沿（英文）》 2015年 第9卷 第2期   页码 216-223 doi: 10.1007/s11705-015-1518-2

摘要： The process of activating coal spoil (CS) in order to recover aluminum as a high value product was investigated. The CS was first characterized by X-ray fluorescence (XRF), X-ray diffraction (XRD) and thermogravimetric analysis-differential scanning calorimetry (TGA-DSC) in order to determine the chemical and mineral compositions of the CS. Then a mechanothermal activation method was adopted to increase the aluminum activity in the coal spoil. Over 95% of the aluminum in the CS could be extracted using this activation method. The mechanothermal activation process promoted the destruction of kaolinite structures and hindered the formation of amorphous -Al O . This resulted in a high aluminum leaching activity in the mechanothermally activated CS.

关键词： coal spoil     mechanothermal compound activation     leaching    

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Nonlinear analysis of pre-tensioned glass wall facade by stability function with initial imperfection

Siu-Lai CHAN, Yaopeng LIU, Andy LEE,

《结构与土木工程前沿（英文）》 2010年 第4卷 第3期   页码 376-382 doi: 10.1007/s11709-010-0086-2

摘要： Pre-tensioned high strength trusses using alloy steel bar are widely used as glass wall supporting systems because of the high degree of transparency. The breakage of glass panes in this type of system occurs occasionally, likely to be due to error in design and analysis in addition to other factors like glass impurity and stress concentration around opening in a spider system. Most design does not consider the flexibility of supports from finite stiffness of supporting steel or reinforced concrete beams. The resistance of lateral wind pressure of the system makes use of high tension force coupled with the large deflection effect, both of which are affected by many parameters not generally considered in conventional structures. In the design, one must therefore give a careful consideration on various effects, such as support settlement due to live loads and material creep, temperature change, pre-tension force, and wind pressure. It is not uncommon to see many similar glass wall systems fail in the wind load test chambers under a design wind speed. This paper presents a rigorous analysis and design of this type of structural systems used in a project in Hong Kong, China. The stability function with initial curvature is used in place of the cubic function, which is only accurate for linear analysis. The considerations and analysis techniques are believed to be of value to engineers involved in the design of the structural systems behaving nonlinearly.

关键词： tension system     glass wall     nonlinear analysis     pre-tensioning     second-order analysis    

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Leaching toxicity characteristics of municipal solid waste incineration bottom ash

Khamphe PHOUNGTHONG,Yi XIA,Hua ZHANG,Liming SHAO,Pinjing HE

《环境科学与工程前沿（英文）》 2016年 第10卷 第2期   页码 399-411 doi: 10.1007/s11783-015-0819-5

摘要： The continuously increasing production of municipal solid waste incineration bottom ash (MSWIBA) has promoted its utilization as construction material and raised environmental concern. The physico-chemical properties and leaching behavior of MSWIBA were studied, and ecotoxicological testing using a luminescent bacterium bioassay was performed to assess the ecological pollution risks associated with its leached constituents. The MSWIBA was leached by two types of leachants, H SO /HNO and HAc solution, at different liquid to solid ratios and contact times. The concentrations of heavy metals and anions in the leachates were analyzed. Multivariate statistical analyses, including principle component analysis, Pearson's correlation analysis and hierarchical cluster analysis, were used to evaluate the contributions of the constituents to the toxicity ( ) of the MSWIBA leachate. The statistical analyses of the ecotoxicological results showed that the Ba, Cr, Cu, Pb, F and total organic carbon (TOC) concentrations were closely correlated with the value, and these substances were the main contributors to the ecotoxicity of the MSWIBA leachate. In addition, the cluster of these variables indicated similar leaching behaviors. Overall, the research demonstrated that the ecotoxicological risks resulting from MSWIBA leaching could be assessed before its utilization, which provides crucial information for the adaptation of MSWIBA as alternative materials.

关键词： Municipal solid waste incineration     bottom ash     alternative material     leaching tests     toxicity     Vibrio qinghaiensis (Q67)    

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A pre-compensation method of the systematic contouring error for repetitive command paths

D. L. ZHANG,Y. H. CHEN,Y. P. CHEN

《机械工程前沿（英文）》 2015年 第10卷 第4期   页码 367-372 doi: 10.1007/s11465-015-0367-5

摘要：

For a repetitive command path, pre-compensating the contouring error by modifying the command path is practical. To obtain the pre-compensation value with better accuracy, this paper proposes the use of a back propagation neural network to extract the function of systematic contouring errors. Furthermore, by using the extracted function, the contouring error can be easily pre-compensated. The experiment results verify that the proposed compensation method can effectively reduce contouring errors.

关键词： contouring error     pre-compensation     motion control system     back propagation (BP) neural network    

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Experimental and parametrical investigation of pre-stressed ultrahigh-performance fiber-reinforced concrete

《结构与土木工程前沿（英文）》 2023年 第17卷 第3期   页码 411-428 doi: 10.1007/s11709-023-0928-3

摘要： In this study, ultrahigh-performance fiber-reinforced concrete (UHPFRC) used in a type B70 concrete sleeper is investigated experimentally and parametrically. The main parameters investigated are the steel fiber volume fractions (0%, 0.5%, 1%, and 1.5%). Under European standards, 35 UHPFRC sleepers are subjected to static bending tests at the center and rail seat sections, and the screw on the fastening system is pulled out. The first cracking load, failure load, failure mode, crack propagation, load–deflection curve, load–crack width, and failure load from these tests are measured and compared with those of a control sleeper manufactured using normal concrete C50. The accuracy of the parametric study is verified experimentally. Subsequently, the results of the study are applied to UHPFRC sleepers with different concrete volumes to investigate the effects of the properties of UHPFRC on their performance. Experimental and parametric study results show that the behavior of UHPFRC sleepers improves significantly when the amount of steel fiber in the mix is increased. Sleepers manufactured using UHPFRC with a steel fiber volume fraction of 1% and a concrete volume less than 25% that of standard sleeper B70 can be used under the same loads and requirements, which contributes positively to the cost and surrounding environment.

关键词： pre-stressed concrete sleeper     ultrahigh performance fiber-reinforced concrete     pull-out test     static bending test     steel fiber     aspect ratio     volume fraction    

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Investigation into viability of using two-stage (pre-placed aggregate) concrete in Irish setting

John O’MALLEY, Hakim S. ABDELGADER,

《结构与土木工程前沿（英文）》 2010年 第4卷 第1期   页码 127-132 doi: 10.1007/s11709-010-0007-4

摘要： Two-stage (pre-placed aggregate) concrete (TSC) consists of coarse aggregate, which is first deposited into the formwork, and grout, which is later pumped into the formwork from the bottom up to bind the stone together into a monolith. During the course of this study the formation of grout for two stage concrete was investigated using readily available 5 mm sand mixed in a slow speed paddle mixer.  Silica fume and a superplasticizer were used in the mix to see if the necessary stability and fluidity could be achieved without the use of a specialized plant, essentially to see if TSC could be produced on a small scale using native Irish aggregates. A much higher degree of sedimentation was recorded during testing than was expected. As a result, the use of 5 mm sand and a slow speed mixer in combination were found to be not conducive to the successful production of TSC grout, without further research and testing.

关键词： grout     pre-placed     concrete     two-stage concrete (TSC)    

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矿浆电解过程的浸出机理

杨显万,张英杰,邓纶浩,邱定蕃

《中国工程科学》 2000年 第2卷 第6期   页码 49-51

摘要：

介绍了高铅铜型难处理金矿矿浆电解浸出机理的研究结果。金精矿在矿浆电解时，铅的浸出可通过化学溶解、化学氧化、阳极氧化三种途径；铅浸出的主要途径是靠化学溶解，矿粒与阳极接触而被氧化对浸出的贡献不大。

关键词： 矿浆电解     浸出     机理    

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标题 作者 时间 类型 操作

Study on the microwave-assisted extraction of polyphenols from tea

Liyun WANG, Peiyong QIN, Yan HU,

期刊论文

Characteristics of the stabilized/solidified municipal solid wastes incineration fly ash and the leaching

Yan SHAO,Haobo HOU,Guangxing WANG,Sha WAN,Min ZHOU

期刊论文

Assessment of leaching behavior and human bioaccessibility of rare earth elements in typical hospital

Chunfeng Wang, Guanfei Chen, Yanchen Zhu, Dan Yao, Wanfeng Wang, Lianjun Wang

期刊论文

Investigation of Cu leaching from municipal solid waste incinerator bottom ash with a comprehensive approach

Jun YAO, Wenbing LI, Fangfang XIA, Jing WANG, Chengran FANG, Dongsheng SHEN

期刊论文

The influence of curing conditions on the mechanical properties and leaching of inorganic polymers made

Remus I. Iacobescu, Valérie Cappuyns, Tinne Geens, Lubica Kriskova, Silviana Onisei, Peter T. Jones, Yiannis Pontikes

期刊论文

Reinforcement of the two-stage leaching of laterite ores using surfactants

Peiyu Zhang, Hairui Wang, Jingcheng Hao, Jiwei Cui

期刊论文

Oxidative leaching kinetics of molybdenum-uranium ore in H

T. A. Lasheen, M. E. El-Ahmady, H. B. Hassib, A. S. Helal

期刊论文

铜阳极泥预处理连续加压酸浸工艺开发研究

王吉坤,冯桂林

期刊论文

Leaching of aluminum from coal spoil by mechanothermal activation

Xiaoxue SUN,Yuzhu SUN,Jianguo YU

期刊论文

Nonlinear analysis of pre-tensioned glass wall facade by stability function with initial imperfection

Siu-Lai CHAN, Yaopeng LIU, Andy LEE,

期刊论文

Leaching toxicity characteristics of municipal solid waste incineration bottom ash

Khamphe PHOUNGTHONG,Yi XIA,Hua ZHANG,Liming SHAO,Pinjing HE

期刊论文

A pre-compensation method of the systematic contouring error for repetitive command paths

D. L. ZHANG,Y. H. CHEN,Y. P. CHEN

期刊论文

Experimental and parametrical investigation of pre-stressed ultrahigh-performance fiber-reinforced concrete

期刊论文

Investigation into viability of using two-stage (pre-placed aggregate) concrete in Irish setting

John O’MALLEY, Hakim S. ABDELGADER,

期刊论文

矿浆电解过程的浸出机理

杨显万,张英杰,邓纶浩,邱定蕃

期刊论文