Yu Tian’s research while affiliated with Tokyo Institute of Technology and other places

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Publications (5)


Application of micro-scale correlation analysis to estimate metal speciation and the matrix in municipal solid waste incineration fly ash
  • Article

February 2020

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67 Reads

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5 Citations

Journal of Material Cycles and Waste Management

Hiroki Kitamura

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Yu Tian

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Micro-scale correlation analysis was applied to estimate metal speciation and the matrix in municipal solid waste incineration (MSWI) fly ash in this study. The results showed that dominant metal speciation and the bonding states with fly ash matrix are different in individual fly ash particle. Micro-scale correlation analysis also suggests metal behaviors in fly ash formation processes. Metal oxides likely react with and/or are trapped in Al/Ca/Si-based matrix such as aluminosilicate in the gas phase and then followed by KCl/NaCl adsorption on the surface. Zinc can possibly form other speciation depending on combustion condition. Zinc chlorides (ZnCl2 and/or K2ZnCl4) and Zn spinels (ZnAl2O4 and ZnFe2O4) are not trapped in Al/Ca/Si-based matrix, however, adsorbed on the surface together with KCl/NaCl-based aggregates. Because metal oxides basically combine with and/or are trapped in Al/Ca/Si-based matrix, metal leachability might be controlled by not only metal oxide leachability but also leachability of Al/Ca/Si-based matrix around metal oxides.


Heterogeneities of fly ash particles generated from a fluidized bed combustor of municipal solid waste incineration

January 2020

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97 Reads

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5 Citations

Journal of Material Cycles and Waste Management

Although municipal solid waste incineration fly ash are fine particles and a priori considered as homogeneous, they have complicated structures inside their bodies. This study quantitatively investigated two categories of heterogeneity of fly ash produced from a fluidized bed combustor. They are the heterogeneity of a single fly ash particle body (intra-particle heterogeneity) and heterogeneity among fly ash particles (inter-particle heterogeneity). In the surface and semi-soluble components, Ca has smaller intra-particle heterogeneity than Al and Si. These results and ternary diagram analysis suggest that semi-soluble components consisted of mainly Ca-based matrices such as CaCO3 and unreacted Ca(OH)2 in which aluminosilicate domains. All major elements, excluding Fe and Ti, are 3–66% higher inter-particle heterogeneities on the surface than semi-soluble and insoluble core components. It shows that the surface component of the fly ash is more heterogeneous than other components of fly ash particles. Fly ash from fluidized bed combustor has intra- and inter-particle heterogeneity similar to stoker combustor. Besides, heterogeneity analysis can explain the fly ash formation process. Heterogeneity analysis suggests that Si plays more critical roles in the fly ash formation process of the fluidized bed combustor than that of the stoker combustor. Fly ash has heterogeneous bodies, and it might give non-negligible impacts on the leaching of metals included in fly ash components.


Intra- and inter-particle heterogeneity of municipal solid waste incineration fly ash particles

March 2019

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58 Reads

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7 Citations

Journal of Material Cycles and Waste Management

This study firstly investigated elemental heterogeneity of municipal solid waste incineration (MSWI) fly ash particles. Two types of heterogeneities were measured quantitatively focusing on three structural components of fly ash particles. They are internal heterogeneity of individual fly ash particles (intra-particle heterogeneity) and inter-particle heterogeneities among fly ash particles. On the surface of fly ash particles, Cl, K, and Na have 0–82% larger intra-particle heterogeneities than Al, Ca, and Si owing to KCl/NaCl-based aggregates. Smaller intra-particle heterogeneity of Ca in semi-soluble component than those of Al and Si suggest that semi-soluble Al/Ca/Si-based matrices around insoluble cores are Ca-based materials including aluminosilicate domains. Inter-particle heterogeneities of Al, Ca, and Si in semi-soluble and insoluble components are 9–40% and 49–352% higher than those of fly ash particle surface, respectively. Inter-particle heterogeneity analysis also suggests that insoluble components mainly consists of Si-, Al-, or Ca-rich cores. MSWI fly ash particles have both internal heterogeneities inside their bodies and also are heterogeneous in inter-particle level. When MSWI fly ash becomes wet during chelate treatment, it changed intra-particle heterogeneity as well as inter-particle heterogeneity. Their variations were contrast depending on element and site (fly ash particle component).


Analyzed experimental samples by point analysis of SEM-EDX
Average elemental contents of metal-rich and metal-poor insoluble residual materials of JLT46
Average elemental contents of metal-rich and metal-poor insoluble residual materials of TCLP
Transfer of soluble components of the same fly ash particle surface (Kitamura et al. 2014)
Intensity changes of major elements by transfer of soluble components before and after the first moistening along A to B shown in Fig. 12

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Impact of secondary generated minerals on toxic element immobilization for air pollution control fly ash of a municipal solid waste incinerator
  • Article
  • Publisher preview available

July 2018

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121 Reads

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10 Citations

Environmental Science and Pollution Research

Impacts of secondary generated minerals on mineralogical and physical immobilization of toxic elements were investigated for chelate-treated air pollution control (APC) fly ash of a municipal solid waste incinerator. Scanning electron microscope (SEM) observation showed that ettringite was generated after the moistening treatment with/without chelate. Although ettringite can incorporate toxic elements into its structure, elemental analysis by energy dispersive X-ray could not find concentrated points of toxic elements in ettringite structure. This implies that mineralogical immobilization of toxic element by the encapsulation to ettringite structure seems to be limited. Physical immobilization was also investigated by SEM observation of the same APC fly ash particles before and after the moistening treatment. The transfer of soluble elements was inhibited only when insoluble minerals such as gypsum were generated and covered the surface of fly ash particles. Neoformed insoluble minerals prevented soluble elements from leaching and transfer. However, such physical immobilization seems to be limited because insoluble mineral formation with surface coverage was monitored only one time of more than 20 observations. Although uncertainty owing to limited samples with limited observations should be considered, this study concludes that mineralogical and physical immobilization of toxic elements by secondary minerals is limited although secondary minerals are always generated on the surface of APC fly ash particles during chelate treatment.

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GEOCHEMICAL FORM ANALYSIS OF TITANIUM IN CHELATE-TREATED MUNICIPAL SOLID WASTE INCINERATION FLY ASH PARTICLES EMPLOYING CORRELATION ANALYSIS OF ELEMENTAL DISTRIBUTION LINE PROFILES

January 2017

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49 Reads

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3 Citations

Journal of Japan Society of Civil Engineers Ser G (Environmental Research)

A new method to analyze metal species in municipal solid waste incineration (MSWI) fly ash employing correlation analysis of elemental distribution line profiles was investigated. Titanium species in chelatetreated MSWI fly ash were estimated by this method. After treatments of fly ash by leaching experiments with different solvents, it showed that heavy metals were easily observed on semi-soluble and/or insoluble matrix of fly ash particles by SEM-EDX. Correlation analysis of elemental distribution line profiles showed that crystalline titanium species in fly ash were rutile (TiO2) and/or perovskite (CaTiO3). They were incorporated in aluminosilicate phase like gehlenite (Ca2Al2SiO7) and amorphous minerals. In addition, some of non-crystalline titanium seems to combine with aluminosilicate. Correlation analysis of elemental distribution line profiles by SEM-EDX could estimate crystalline and non-crystaline titanium species, which could not be indentifed by XRD analysis.

Citations (5)


... The phase is Mantovani et al. (2021). Last, ZnCl 2 was found only in one spectrum (Zn2_1); this compound was found mainly in FA (Cai et al., 2015;Kitamura et al., 2020) but also in BA where its presence can be explained by the encapsulation of chloride within sintered BA particles (Rissler et al., 2020). ...

Reference:

Potentially Toxic Elements speciation in Bottom Ashes from a Municipal Solid Waste Incinerator: a combined SEM-EDS, µ-XRF and µ-XANES study
Application of micro-scale correlation analysis to estimate metal speciation and the matrix in municipal solid waste incineration fly ash
  • Citing Article
  • February 2020

Journal of Material Cycles and Waste Management

... Despite the significant features of MSWI technology in terms of non-hazardousness, minimization, and resource utilization, the process still emits various pollutants [31]. The MSW with complex compositions gradually decreases in size, and eventually forms PM after fracture, pyrolysis, and oxidation in the furnace [32,33]. PM is mostly irregularly shaped aggregates, with relatively few spherical bodies, rod-like aggregates, and flocculent aggregates. ...

Heterogeneities of fly ash particles generated from a fluidized bed combustor of municipal solid waste incineration
  • Citing Article
  • January 2020

Journal of Material Cycles and Waste Management

... Other countries (e.g., Japan) rely on MSWI methods at higher temperatures (> 1200 °C), targeting the complete destruction of organic pollutants (e.g., dioxin, furan) and the vitrification of the incineration residues (Ecke et al. 2000;Tanigaki et al. 2012;Shiota et al. 2017). MSWI represents a heterogeneous treatment process, which is heavily influenced by the waste input and local temperature gradients in the furnace during the incineration, which result in MSWI residues of variable chemical and mineralogical composition (Chang et al. 2001;Kitamura et al. 2019;Huber et al. 2020). ...

Intra- and inter-particle heterogeneity of municipal solid waste incineration fly ash particles
  • Citing Article
  • March 2019

Journal of Material Cycles and Waste Management

... Its primary sources are the combustion and emissions resulting from vehicles powered by fuel, as well as the degradation of automotive components [28]. The primary constituents found in PM 2.5 consist of black carbon, polycyclic aromatic hydrocarbons (PAHs), aryl hydrocarbons, volatile organic hydrocarbons, heavy metals, organic compounds, minerals, inorganic ions, and biological materials [29][30][31][32][33][34][35][36]. Collectively, these components account for a minimum of 79-85% of the total mass [37]. ...

Impact of secondary generated minerals on toxic element immobilization for air pollution control fly ash of a municipal solid waste incinerator

Environmental Science and Pollution Research

... Because SEM-EDX measurement was semi-quantitative owing to no specific calibration, it is noted that comparison of elemental concentrations shown in Fig. 6 still needs careful verification for a solid conclusion. After JLT46 and TCLP, XRD patterns of soluble components such as sylvite and halite disappeared owing to leaching out (see Fig. 7; Kitamura et al. 2017). On the other hand, Al/ Ca/Si-based minerals such as gehlenite (Ca 2 Al 2 SiO 7 ) were identified. ...

GEOCHEMICAL FORM ANALYSIS OF TITANIUM IN CHELATE-TREATED MUNICIPAL SOLID WASTE INCINERATION FLY ASH PARTICLES EMPLOYING CORRELATION ANALYSIS OF ELEMENTAL DISTRIBUTION LINE PROFILES
  • Citing Article
  • January 2017

Journal of Japan Society of Civil Engineers Ser G (Environmental Research)