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Effect of seawater salinity on the synthesis of zeolite from coal fly ash

Yanqing YU, Xiaoliang LI, Xiaolan ZOU, Xiaobin ZHU

《环境科学与工程前沿（英文）》 2014年 第8卷 第1期   页码 54-61 doi: 10.1007/s11783-013-0493-4

摘要： A novel method for the synthesis of zeolite was developed in this paper. The synthesis was carried out by hydrothermal activation after alkali fusion and coal fly ash (CFA) was used as raw material with seawater of different salinities. Seawater salinity was varied from 32 to 88 for zeolite crystallization during the hydrothermal process. The results show that seawater salinity plays an important role in zeolite synthesis with CFA during hydrothermal treatment. The products were a mixture of NaX zeolite and hydroxysodalite; seawater salinity more strongly affected the crystallization than the type and chemical composition of the zeolites. The yield of CFA transformed into zeolite gradually rose with the increase in salinity, reaching a transformation rate of 48%–62% as the salinity increased from 32 to 88, respectively. The proposed method allows for the efficient disposal of by-products; therefore, the application of seawater in zeolite synthesis presents promising economic and ecological benefits.

关键词： coal fly ash (CFA)     seawater salinity     zeolite synthesis    

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Porous silica synthesis out of coal fly ash with no residue generation and complete silicon separation

《环境科学与工程前沿（英文）》 2023年 第17卷 第9期 doi: 10.1007/s11783-023-1712-2

摘要：

● Both amorphous and crystalline silicon are completely separated from coal fly ash.

关键词： Coal fly ash     Alkali fusion     Micro-/meso-porous Si     Zeolite MCM-48     Crystalline transformation    

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Physical and mechanical properties of municipal solid waste incineration residues with cement and coalfly ash using X-ray Computed Tomography scanners

Toshifumi MUKUNOKI, Ta Thi HOAI, Daisuke FUKUSHIMA, Teppei KOMIYA, Takayuki SHIMAOKA

《结构与土木工程前沿（英文）》 2019年 第13卷 第3期   页码 640-652 doi: 10.1007/s11709-018-0502-6

摘要： A significant volume of Municipal Solid Waste incineration bottom ash and fly ash (i.e., incineration residues) are commonly disposed as landfill. Meanwhile, reclamation of landfill sites to create a new land space after their closure becomes an important goal in the current fewer and fewer land availability scenario in many narrow countries. The objective of this study is to reclaim incineration residue materials in the landfill site by using cement and coal fly ash as stabilizers aiming at performing quality check as new developed materials before future construction. Indeed, physical and mechanical properties of these new materials should be initially examined at the micro scale, which is the primary fundamental for construction at larger scale. This research examines quantitative influences of using the combination of cement and coal fly ash at different ratio on the internal structure and ability of strength enhancement of incineration residues when suffering from loading. Couple of industrial and micro-focus X-ray computed tomography (CT) scanners combined with an image analysis technique were utilized to characterize and visualize the behavior and internal structure of the incineration residues-cement-coal fly ash mixture under the series of unconfined compression test and curing period effect. Nine types of cement solidified incineration residues in term of different curing period (i.e., 7, 14, 28 days) and coal fly ash addition content (i.e., 0%, 9%, 18%) were scanned before and after unconfined compression tests. It was shown that incineration residues solidified by cement and coal fly ash showed an increase in compression strength and deformation modulus with curing time and coal fly ash content. Three-dimension computed tomography images observation and analysis confirmed that solidified incineration residues including incineration bottom and fly ash as well as cement and coal fly ash have the deliquescent materials. Then, it was studied that stabilized parts play a more important role than spatial void distribution in increment or reduction of compression strength.

关键词： mechanical property     municipal solid waste incineration residues     coal fly ash     unconfined compression test     image analysis     X-Ray Computed Tomography scanners    

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Synthesis of zeolite Na-P1 from coal fly ash produced by gasification and its application as adsorbent

Yixin Zhang, Lu Zhou, Liqing Chen, Yang Guo, Fanhui Guo, Jianjun Wu, Baiqian Dai

《化学科学与工程前沿（英文）》 2021年 第15卷 第3期   页码 518-527 doi: 10.1007/s11705-020-1926-9

摘要： The coal fly ash produced by gasification is estimated to be over 80 million ton per year in China by 2021. It has mainly been disposed as solid waste by landfill. There is lack of study focused on its utilization. In this paper, the coal fly ash produced by gasification was at first analyzed and then applied to synthesize zeolite as an adsorbent. The effects of synthesis conditions on the cation exchange capacity (CEC) of zeolite were investigated. The results from X-ray diffraction and scanning electron microscope indicated that the crystallinity of the synthesized zeolite is the most important factor to affect the CEC. When the synthesized zeolite with the highest CEC (275.5 meq/100 g) was used for the adsorption of Cr(VI) from aqueous solution, the maximum adsorption capacity for Cr(VI) was found to be 17.924 mg/g. The effects of pH, contact time and initial concentration on the adsorption of Cr(VI) were also investigated. The adsorption kinetics and isotherms can be well described by the pseudo-second-order model and Langmuir isotherm model, respectively.

关键词： coal fly ash     gasification     zeolite     Na-P1     chromium(VI)    

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Use of zeolitized coal fly ash in the simultaneous removal of ammonium and phosphate from aqueous solution

WU Deyi, HU Zhanbo, WANG Xinze, HE Shengbing, KONG Hainan

《环境科学与工程前沿（英文）》 2007年 第1卷 第2期   页码 213-220 doi: 10.1007/s11783-007-0037-x

摘要： Discharge of wastewater containing nitrogen and phosphate can cause eutrophication. Therefore, the development of an efficient material for the immobilization of the nutrients is important. In this study, a low calcium fly ash and high calcium fly ash were converted into zeolite using the hydrothermal method. The removal of ammonium and phosphate that coexist in aqueous solution by the synthesized zeolites were studied. The results showed that zeolitized fly ash could efficiently eliminate ammonium and phosphate at the same time. Saturation of zeolite with Ca rather than N favored the removal of both ammonium and phosphate because the cation exchange reaction by the NH resulted in the release of Ca into the solution and precipitation of Ca with PO followed. An increase in the temperature elevated the immobilization of phosphate whereas it abated the removal of ammonium. Nearly 60% removal efficiency for ammonium was achieved in the neutral pH range from 5.5 to 10.5, while the increase or decrease in pH out of the neutral range lowered the adsorption. In contrast, the removal of phosphate approached 100% at a pH lower than 5.0 or higher than 9.0, and less phosphate was immobilized at neutral pH. However, there was still a narrow pH range from 9.0 to 10.5 favoring the removal of both ammonium and phosphate. It was concluded that the removal of ammonium was caused by cation exchange; the contribution of NH volatilization to immobilization at alkaline conditions (up to pH level of 11.4) was limited. With respect to phosphate immobilization, the mechanism was mainly the formation of precipitate as Ca(PO) within the basic pH range or as FePO and AlPO within acidic pH range.
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Pyrolysis of WEEE plastics using catalysts produced from fly ash of coal gasification

Marika Benedetti, Lorenzo Cafiero, Doina De Angelis, Alessandro Dell’Era, Mauro Pasquali, Stefano Stendardo, Riccardo Tuffi, Stefano Vecchio Ciprioti

《环境科学与工程前沿（英文）》 2017年 第11卷 第5期 doi: 10.1007/s11783-017-0998-3

摘要： Catalytic pyrolysis of thermoplastics extracted from waste electrical and electronic equipment (WEEE) was investigated using various fly ash-derived catalysts. The catalysts were prepared from fly ash by a simple method that basically includes a mechanical treatment followed by an acid or a basic activation. The synthesized catalysts were characterized using various analytical techniques. The results showed that not treated fly ash (FA) is characterized by good crystallinity, which in turn is lowered by mechanical and chemical treatment (fly ash after mechanical and acid activation, FAMA) and suppressed almost entirely down to let fly ash become completely amorphous (fly ash after mechanical and basic activation FAMB). Simultaneously, the surface area resulted increased. Subsequently, FA, FAMB and FAMA were used in the pyrolysis of a WEEE plastic sample at 400°C and their performance were compared with thermal pyrolysis at the same temperature. The catalysts principally improve the light oil yield: from 59wt.% with thermal pyrolysis to 83 wt.% using FAMB. The formation of styrene in the oil is also increased: from 243 mg/g with thermal pyrolysis to 453 mg/g using FAMB. As a result, FAMB proved to be the best catalyst, thus producing also the lowest and the highest amount of char and gas, respectively.

关键词： Waste electrical and electronic equipment (WEEE) plastic mixture     Pyrolysis     Catalyst     Fly ash     Oil    

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Mercury emission and adsorption characteristics of fly ash in PC and CFB boilers

Li JIA, Baoguo FAN, Xianrong ZHENG, Xiaolei QIAO, Yuxing YAO, Rui ZHAO, Jinrong GUO, Yan JIN

《能源前沿（英文）》 2021年 第15卷 第1期   页码 112-123 doi: 10.1007/s11708-020-0682-3

摘要： The mercury emission was obtained by measuring the mercury contents in flue gas and solid samples in pulverized coal (PC) and circulating fluidized bed (CFB) utility boilers. The relationship was obtained between the mercury emission and adsorption characteristics of fly ash. The parameters included unburned carbon content, particle size, and pore structure of fly ash. The results showed that the majority of mercury released to the atmosphere with the flue gas in PC boiler, while the mercury was enriched in fly ash and captured by the precipitator in CFB boiler. The coal factor was proposed to characterize the impact of coal property on mercury emissions in this paper. As the coal factor increased, the mercury emission to the atmosphere decreased. It was also found that the mercury content of fly ash in the CFB boiler was ten times higher than that in the PC boiler. As the unburned carbon content increased, the mercury adsorbed increased. The capacity of adsorbing mercury by fly ash was directly related to the particle size. The particle size corresponding to the highest content of mercury, which was about 560 ng/g, appeared in the range from 77.5 to 106 µm. The content of mesoporous (4–6 nm) of the fly ash in the particle size of 77.5–106 µm was the highest, which was beneficial to adsorbing the mercury. The specific surface area played a more significant role than specific pore volume in the mercury adsorption process.

关键词： mercury     combustion modes     coal property     fly ash     particle size    

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Experimental studies of ash film fractions based on measurement of cenospheres geometry in pulverizedcoal combustion

Siqi LIU, Yanqing NIU, Liping WEN, Yang LIANG, Bokang YAN, Denghui WANG, Shi’en HUI

《能源前沿（英文）》 2021年 第15卷 第1期   页码 91-98 doi: 10.1007/s11708-020-0806-9

摘要： In pulverized coal particle combustion, part of the ash forms the ash film and exerts an inhibitory influence on combustion by impeding the diffusion of oxygen to the encapsulated char core, while part of the ash diffuses toward the char core. Despite the considerable ash effects on combustion, the fraction of ash film still remains unclear. However, the research of the properties of cenospheres can be an appropriate choice for the fraction determination, being aware that the formation of cenospheres is based on the model of coal particles with the visco-plastic ash film and a solid core. The fraction of ash film is the ratio of the measuring mass of ash film and the total ash in coal particle. In this paper, the Huangling bituminous coal with different sizes was burnt in a drop-tube furnace at 1273, 1473, and 1673 K with air as oxidizer. A scanning electron microscope (SEM) and cross-section analysis have been used to study the geometry of the collected cenospheres and the effects of combustion parameters on the fraction of ash film. The results show that the ash film fraction increases with increasing temperature and carbon conversion ratio but decreases with larger sizes of coal particles. The high fraction of ash film provides a reasonable explanation for the extinction event at the late burnout stage. The varied values of ash film fractions under different conditions during the dynamic combustion process are necessary for further development of kinetic models.

关键词： ash film fraction     cenospheres     coal combustion     fly ash    

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Effects of sulfur on variations in the chemical speciation of heavy metals from fly ash glass

《环境科学与工程前沿（英文）》 2023年 第17卷 第10期 doi: 10.1007/s11783-023-1728-7

摘要：

● A higher sulfur content reduced the curing rate of Cr in glass.

关键词： Dechlorinated fly ash     SO3     Heavy metal     Chemical speciation     Glass solidification    

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Service life prediction of fly ash concrete using an artificial neural network

《结构与土木工程前沿（英文）》 2021年 第15卷 第3期   页码 793-805 doi: 10.1007/s11709-021-0717-9

摘要： Carbonation is one of the most aggressive phenomena affecting reinforced concrete structures and causing their degradation over time. Once reinforcement is altered by carbonation, the structure will no longer fulfill service requirements. For this purpose, the present work estimates the lifetime of fly ash concrete by developing a carbonation depth prediction model that uses an artificial neural network technique. A collection of 300 data points was made from experimental results available in the published literature. Backpropagation training of a three-layer perceptron was selected for the calculation of weights and biases of the network to reach the desired performance. Six parameters affecting carbonation were used as input neurons: binder content, fly ash substitution rate, water/binder ratio, CO2 concentration, relative humidity, and concrete age. Moreover, experimental validation carried out for the developed model shows that the artificial neural network has strong potential as a feasible tool to accurately predict the carbonation depth of fly ash concrete. Finally, a mathematical formula is proposed that can be used to successfully estimate the service life of fly ash concrete.

关键词： concrete     fly ash     carbonation     neural networks     experimental validation     service life    

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Direct synthesis of carbon nanotubes on fly ash particles to produce carbon nanotubes/fly ash composites

Fangxian LI, Cheng ZHOU, Pengfei YANG, Beihan WANG, Jie HU, Jiangxiong WEI, Qijun YU

《结构与土木工程前沿（英文）》 2019年 第13卷 第6期   页码 1405-1414 doi: 10.1007/s11709-019-0564-0

摘要： Fly ash was used as catalytic support for carbon nanotubes (CNTs) growth by chemical vapor deposition (CVD) due to having ideal compositions (SiO , Al O , and Fe O ). In this paper, CNTs were synthesized on Ni catalyst/fly ash substrate using CVD method. The influence of parameters (e.g., reaction temperature and gas flow rate) on the carbon yield and structure of the resulting CNTs was on the carbon yield and structure of the resulting CNTs was investigated by thermo-gravimetric analyses, Scanning electron microscopy, and Raman spectroscopy analysis. The results indicated that the growth temperature controlling had a significant effect on the diameter of CNTs. And the proper acetylene and hydrogen flow rate would decrease in defect density and increase in yield of as-grown CNTs on fly ash. Finally, the amorphous carbon on the surface of as-grown CNTs were removed by heating in air. Experimental results showed that the hydrophobic of the annealed CNTs was weak due to introducing functional groups to the surface of CNTs.

关键词： carbon nanotubes     fly ash     chemical vapor deposition     parameters     purification    

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Effect of fly ash replacement level on the fracture behavior of concrete

Mahdi AREZOUMANDI, Jeffery S. VOLZ

《结构与土木工程前沿（英文）》 2013年 第7卷 第4期   页码 411-418 doi: 10.1007/s11709-013-0228-4

摘要： The production of portland cement–the key ingredient in concrete–generates a significant amount of carbon dioxide. However, due to its incredible versatility, availability, and relatively low cost, concrete is the most consumed manmade material on the planet. One method of reducing concrete’s contribution to greenhouse gas emissions is the use of fly ash to replace a significant amount of the cement. ?This study presents the results of an experimental investigation that evaluates effect of fly ash replacement level on the fracture energy of concrete. This study includes four mixes with 0%, 30%, 50%, and 70% fly ash as a cement replacement. This experimental program consisted of 32 fracture beams to study the fracture behavior of concrete. The experimental fracture energies were compared with the fracture energy provisions of different design codes and also different analytical equations. Furthermore, statistical data analyses (parametric and non-parametric) were performed to evaluate whether or not there is any statistically significant difference between the experimental fracture energies of different mixes. Results of these statistical tests show that the mix with higher level of fly ash replacement level has higher fracture energy.

关键词： concrete     fracture energy     fly ash    

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Accelerated engineering properties of high and low volume fly ash concretes reinforced with glued steel

Vallarasu Manoharan SOUNTHARARAJAN, Dr. Anandan SIVAKUMAR

《结构与土木工程前沿（英文）》 2013年 第7卷 第4期   页码 429-445 doi: 10.1007/s11709-013-0226-6

摘要： The present study focuses on the improvement of pozzolanic reaction of fly ash particles with the cement hydration products. Low and high volume fly ash concrete mixtures were studied systematically with the addition of accelerating admixtures and accelerated curing of the concrete specimens in a steam chamber for 18 h at 75°C. Also, the reinforcing effects of glued steel fibers addition on the compressive and flexural performance of fly ash concrete were investigated. The test results indicated that the addition of accelerator improved the rate of hardening and the inclusion of steel fibers provided higher flexural performance. Also, it can be noted that the high volume fly ash (50%) addition in concrete showed a reduction in strength; however, the addition of accelerator has compensated the deceleration in strength gain. The proper selection of concrete ingredients, addition of accelerator and initial steam curing for 18 h showed better improvement on the engineering properties in fly ash concrete. A maximum increase (41.7%) in compressive strength of fly ash concrete around 52.90 MPa was noticed for 25% fly ash substitution and 1.5% steel fibers addition. Dynamic elastic modulus was also calculated in loaded concrete specimen using ultrasonic pulse velocity test and showed a good agreement with the experimental value.

关键词： fly ash     pozzolanic index     steam curing     superplasticizer     accelerator     steel fibres     elastic modulus    

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Effects of seeding nucleation agent on geopolymerization process of fly-ash geopolymer

Lapyote PRASITTISOPIN, Issara SEREEWATTHANAWUT

《结构与土木工程前沿（英文）》 2018年 第12卷 第1期   页码 16-25 doi: 10.1007/s11709-016-0373-7

摘要： Geopolymer, an inorganic aluminosilicate material activated by alkaline medium solution, can perform as an inorganic adhesive. The geopolymer technology has a viability to substitute traditional concrete made of portland cement (PC) because replacing PC with fly ash leads to reduced carbon dioxide emissions from cement productions and reduced materials cost. Although fly ash geopolymer stimulates sustainability, it is slow geopolymerization reaction poses a challenge for construction technology in term of practicality. The development of increasing geopolymerization reaction rate of the geopolymer is needed. ?The purpose of this study is to evaluate seeding nucleation agents (NA) of fly ash geopolymer that can accelerate polymerization reactions such that the geopolymer can be widely used in the construction industry. Results from the present study indicate that the use of NA (i.e., Ca(OH) ) can be potentially used to increase geopolymerization reaction rate and improve performance characteristics of the fly ash geopolymer product.

关键词： fly ash     geopolymer     nucleation agent     portland cement replacement    

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Fresh and hardened properties of high-performance fiber-reinforced concrete containing fly ash and ricehusk ash: Influence of fiber type and content

Nguyen-Trong HO; Viet Quoc DANG; Minh-Hieu NGUYEN; Chao-Lung HWANG; Trong-Phuoc HUYNH

《结构与土木工程前沿（英文）》 2022年 第16卷 第12期   页码 1621-1632 doi: 10.1007/s11709-022-0884-3

摘要： Although fibers are used only infrequently as an additive in concrete in the construction industry, fiber-enhanced concrete is known to provide a wide range of advantages over conventional concrete. The main objective of this study was to investigate the influences of fiber type and content on the mechanical properties and durability of high-performance fiber-reinforced concrete (HPFRC) designed using a novel densified mixture design algorithm with fly ash and rice husk ash. Three types of fiber, including polypropylene (PP) fiber, steel fiber (SF), and hybrid fiber (HF), were considered. Based on the results, the inclusion of fibers decreased HPFRC flowability, regardless of fiber type. Although the compressive strength of HPFRC with 1.6% PP fiber content was 11.2% below that of the reference HPFRC specimen at 91 d of curing age, the 91-d compressive strengths of both SF and HF-enhanced HPFRC specimens were significantly better than that of the reference HPFRC specimen. Furthermore, the HPFRC specimens incorporating SF and HF both exhibited better splitting tensile and flexural strengths as well as less drying shrinkage than the HPFRC specimens incorporating PP fiber. However, the fiber-enhanced specimens, especially those with added SF, registered less surface electrical resistivity and greater vulnerability to chloride ion penetration than the reference HPFRC specimen.

关键词： high-performance fiber-reinforced concrete     fly ash     rice husk ash     durability     mechanical strength    

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标题 作者 时间 类型 操作

Effect of seawater salinity on the synthesis of zeolite from coal fly ash

Yanqing YU, Xiaoliang LI, Xiaolan ZOU, Xiaobin ZHU

期刊论文

Porous silica synthesis out of coal fly ash with no residue generation and complete silicon separation

期刊论文

Physical and mechanical properties of municipal solid waste incineration residues with cement and coalfly ash using X-ray Computed Tomography scanners

Toshifumi MUKUNOKI, Ta Thi HOAI, Daisuke FUKUSHIMA, Teppei KOMIYA, Takayuki SHIMAOKA

期刊论文

Synthesis of zeolite Na-P1 from coal fly ash produced by gasification and its application as adsorbent

Yixin Zhang, Lu Zhou, Liqing Chen, Yang Guo, Fanhui Guo, Jianjun Wu, Baiqian Dai

期刊论文

Use of zeolitized coal fly ash in the simultaneous removal of ammonium and phosphate from aqueous solution

WU Deyi, HU Zhanbo, WANG Xinze, HE Shengbing, KONG Hainan

期刊论文

Pyrolysis of WEEE plastics using catalysts produced from fly ash of coal gasification

Marika Benedetti, Lorenzo Cafiero, Doina De Angelis, Alessandro Dell’Era, Mauro Pasquali, Stefano Stendardo, Riccardo Tuffi, Stefano Vecchio Ciprioti

期刊论文

Mercury emission and adsorption characteristics of fly ash in PC and CFB boilers

Li JIA, Baoguo FAN, Xianrong ZHENG, Xiaolei QIAO, Yuxing YAO, Rui ZHAO, Jinrong GUO, Yan JIN

期刊论文

Experimental studies of ash film fractions based on measurement of cenospheres geometry in pulverizedcoal combustion

Siqi LIU, Yanqing NIU, Liping WEN, Yang LIANG, Bokang YAN, Denghui WANG, Shi’en HUI

期刊论文

Effects of sulfur on variations in the chemical speciation of heavy metals from fly ash glass

期刊论文

Service life prediction of fly ash concrete using an artificial neural network

期刊论文

Direct synthesis of carbon nanotubes on fly ash particles to produce carbon nanotubes/fly ash composites

Fangxian LI, Cheng ZHOU, Pengfei YANG, Beihan WANG, Jie HU, Jiangxiong WEI, Qijun YU

期刊论文

Effect of fly ash replacement level on the fracture behavior of concrete

Mahdi AREZOUMANDI, Jeffery S. VOLZ

期刊论文

Accelerated engineering properties of high and low volume fly ash concretes reinforced with glued steel

Vallarasu Manoharan SOUNTHARARAJAN, Dr. Anandan SIVAKUMAR

期刊论文

Effects of seeding nucleation agent on geopolymerization process of fly-ash geopolymer

Lapyote PRASITTISOPIN, Issara SEREEWATTHANAWUT

期刊论文

Fresh and hardened properties of high-performance fiber-reinforced concrete containing fly ash and ricehusk ash: Influence of fiber type and content

Nguyen-Trong HO; Viet Quoc DANG; Minh-Hieu NGUYEN; Chao-Lung HWANG; Trong-Phuoc HUYNH

期刊论文