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| 1.
論文 |
論文
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Hasegawa, Hiroshi ; Rahman, Ismail M. M. ; Nakano, Masayoshi ; Begum, Zinnat A. ; Egawa, Yuji ; Maki, Teruya ; Furusho, Yoshiaki ; Mizutani, Satoshi
概要:
Aminopolycarboxylate chelants (APCs) are extremely useful for a variety of industrial applications, including the treatm
…
ent of toxic metal-contaminated solid waste materials. Because non-toxic matrix elements compete with toxic metals for the binding sites of APCs, an excess of chelant is commonly added to ensure the adequate sequestration of toxic metal contaminants during waste treatment operations. The major environmental impacts of APCs are related to their ability to solubilize toxic heavy metals. If APCs are not sufficiently eliminated from the effluent, the aqueous transport of metals can occur through the introduction of APCs into the natural environment, increasing the magnitude of associated toxicity. Although several techniques that focus primarily on the degradation of APCs at the pre-release step have been proposed, methods that recycle not only the processed water, but also provide the option to recover and reuse the metals, might be economically feasible, considering the high costs involved due to the chelants used in metal ion sequestration. In this paper, we propose a separation process for the recovery of metals from effluents that contain an excess of APCs. Additionally, the option of recycling the processed water using a solid phase extraction (SPE) system with an ion-selective immobilized macrocyclic material, commonly known as a molecular recognition technology (MRT) gel, is presented. Simulated effluents containing As(V), Cd(II), Cr(III), Pb(II) or Se(IV) in the presence of APCs at molar ratios of 1:50 in H2O were studied with a flow rate of 0.2 mL min-1. The 'captured' ions in the SPE system were quantitatively eluted with HNO3. The effects of solution pH, metal-chelant stability constants and matrix elements were assessed. Better separation performance for the metals was achieved with the MRT-SPE compared to other SPE materials. Our proposed technique offers the advantage of a non-destructive separation of both metal ions and chelants compared to conventional treatment options for such effluents. © 2011 Elsevier Ltd. All rights reserved.
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| 2.
論文 |
論文
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Hasegawa, Hiroshi ; Rahman, Ismail M. M. ; Nakano, Masayoshi ; Begum, Zinnat A. ; Egawa, Yuji ; Maki, Teruya ; Furusho, Yoshiaki ; Mizutani, Satoshi
概要:
Aminopolycarboxylate chelants (APCs) are extremely useful for a variety of industrial applications, including the treatm
…
ent of toxic metal-contaminated solid waste materials. Because non-toxic matrix elements compete with toxic metals for the binding sites of APCs, an excess of chelant is commonly added to ensure the adequate sequestration of toxic metal contaminants during waste treatment operations. The major environmental impacts of APCs are related to their ability to solubilize toxic heavy metals. If APCs are not sufficiently eliminated from the effluent, the aqueous transport of metals can occur through the introduction of APCs into the natural environment, increasing the magnitude of associated toxicity. Although several techniques that focus primarily on the degradation of APCs at the pre-release step have been proposed, methods that recycle not only the processed water, but also provide the option to recover and reuse the metals, might be economically feasible, considering the high costs involved due to the chelants used in metal ion sequestration. In this paper, we propose a separation process for the recovery of metals from effluents that contain an excess of APCs. Additionally, the option of recycling the processed water using a solid phase extraction (SPE) system with an ion-selective immobilized macrocyclic material, commonly known as a molecular recognition technology (MRT) gel, is presented. Simulated effluents containing As(V), Cd(II), Cr(III), Pb(II) or Se(IV) in the presence of APCs at molar ratios of 1:50 in H2O were studied with a flow rate of 0.2mL min-1. The 'captured' ions in the SPE system were quantitatively eluted with HNO3. The effects of solution pH, metal-chelant stability constants and matrix elements were assessed. Better separation performance for the metals was achieved with the MRT-SPE compared to other SPE materials. Our proposed technique offers the advantage of a non-destructive separation of both metal ions and chelants compared to conventional treatment options for such effluents. © 2011 Elsevier Ltd.
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| 3.
論文 |
論文
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Hasegawa, Hiroshi ; Rahman, Ismail M.M. ; Nakano, Masayoshi ; Begum, Zinnat A. ; Egawa, Yuji ; Maki, Teruya ; Furusho, Yoshiaki ; Mizutani, Satoshi
概要:
Aminopolycarboxylate chelants (APCs) are extremely useful for a variety of industrial applications, including the treatm
…
ent of toxic metal-contaminated solid waste materials. Because non-toxic matrix elements compete with toxic metals for the binding sites of APCs, an excess of chelant is commonly added to ensure the adequate sequestration of toxic metal contaminants during waste treatment operations. The major environmental impacts of APCs are related to their ability to solubilize toxic heavy metals. If APCs are not sufficiently eliminated from the effluent, the aqueous transport of metals can occur through the introduction of APCs into the natural environment, increasing the magnitude of associated toxicity. Although several techniques that focus primarily on the degradation of APCs at the pre-release step have been proposed, methods that recycle not only the processed water, but also provide the option to recover and reuse the metals, might be economically feasible, considering the high costs involved due to the chelants used in metal ion sequestration. In this paper, we propose a separation process for the recovery of metals from effluents that contain an excess of APCs. Additionally, the option of recycling the processed water using a solid phase extraction (SPE) system with an ion-selective immobilized macrocyclic material, commonly known as a molecular recognition technology (MRT) gel, is presented. Simulated effluents containing As(V), Cd(II), Cr(III), Pb(II) or Se(IV) in the presence of APCs at molar ratios of 1:50 in H2O were studied with a flow rate of 0.2mL min-1. The 'captured' ions in the SPE system were quantitatively eluted with HNO3. The effects of solution pH, metal-chelant stability constants and matrix elements were assessed. Better separation performance for the metals was achieved with the MRT-SPE compared to other SPE materials. Our proposed technique offers the advantage of a non-destructive separation of both metal ions and chelants compared to conventional treatment options for such effluents. © 2011 Elsevier Ltd.
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| 4.
論文 |
論文
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Hasegawa, Hiroshi ; Rahman, Ismail M. M. ; Egawa, Yuji ; Sawai, Hikaru ; Begum, Zinnat A. ; Maki, Teruya ; Mizutani, Satoshi
概要:
The metal indium termed as 'rare' in recent days due to its increasing demand in the formulations of electronic and ener
…
gy-related gadgets and scarce supply resources. Hence, the attempts to recover indium from the secondary resources, such as recycling of the indium abundant waste materials, received increasing research focus. The major indium consumption happens in the form of indium tin oxide (ITO) that used for the fabrication of liquid-crystal displays (LCD). The end-of-life LCD screens, termed as ITO-glass hereafter, are an emerging contributor to the global e-waste load and can be an impending secondary source of indium. The present work introduces a new technique for the treatment of waste ITO-glass using aminopolycarboxylate chelants (APCs) in combination with a mechanochemical treatment process. APCs are capable of forming stable complexes with the indium deposited on the ITO-glass, whereas the rate of recovery was not substantial. The mechanochemical treatment induces the destruction of crystalline structure with which the ITO fragments are attached and facilitate the increased indium dissolution with the chelants. The increase was more prominent followed by a decrease in the cumulative processing time from 24 to 6. h when the vitrified ITO-glass was simultaneously crushed and washed with the chelants. The extraction of indium was better at the acidic pH condition, and it was further intensified when the operating temperature was raised to ≥ 120°C. © 2012 Elsevier B.V.
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| 5.
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論文
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Begum, Zinnat A. ; Rahman, Ismail M. M. ; Tate, Yousuke ; Egawa, Yuji ; Maki, Teruya ; Hasegawa, Hiroshi
概要:
The protonation and complex formation equilibria of two biodegradable aminopolycarboxylate chelants {dl-2-(2-carboxymeth
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yl)nitrilotriacetic acid (GLDA) and 3-hydroxy-2,2′-iminodisuccinic acid (HIDS)} with Ni 2+, Cu 2+, Zn 2+, Cd 2+ and Pb 2+ ions were investigated using the potentiometric method at a constant ionic strength of I = 0.10 mol·dm -3 (KCl) in aqueous solutions at 25 ± 0.1 °C. The stability constants of the proton-chelant and metal-chelant species for each metal ion were determined, and the concentration distributions of various complex species in solution were evaluated for each ion. The stability constants (log 10K ML) of the complexes containing Ni 2+, Cu 2+, Zn 2+, Cd 2+ and Pb 2+ ions followed the identical order of log 10K CuL > log 10K NiL > log 10K PbL > log 10K ZnL > log 10K CdL for either GLDA (13.03 > 12.74 > 11.60 > 11.52 > 10.31) or HIDS (12.63 > 11.30 > 10.21 > 9.76 > 7.58). In each case, the constants obtained for metal-GLDA complexes were larger than the corresponding constants for metal-HIDS complexes. The conditional stability constants (log 10 {Mathematical expression}) of the metal-chelant complexes containing GLDA and HIDS were calculated in terms of pH, and compared with the stability constants for EDTA and other biodegradable chelants. © 2012 Springer Science+Business Media New York.
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| 6.
論文 |
論文
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Begum, Zinnat A. ; Rahman, Ismail M. M. ; Tate, Yousuke ; Egawa, Yuji ; Maki, Teruya ; Hasegawa, Hiroshi
概要:
The protonation and complex formation equilibria of two biodegradable aminopolycarboxylate chelants {dl-2-(2-carboxymeth
…
yl)nitrilotriacetic acid (GLDA) and 3-hydroxy-2,2′-iminodisuccinic acid (HIDS)} with Ni 2+, Cu2+, Zn2+, Cd2+ and Pb 2+ ions were investigated using the potentiometric method at a constant ionic strength of I = 0.10 mol·dm-3 (KCl) in aqueous solutions at 25 ± 0.1 C. The stability constants of the proton-chelant and metal-chelant species for each metal ion were determined, and the concentration distributions of various complex species in solution were evaluated for each ion. The stability constants (log10 K ML) of the complexes containing Ni2+, Cu2+, Zn2+, Cd2+ and Pb2+ ions followed the identical order of log10 K CuL > log10 K NiL > log10 K PbL > log10 K ZnL > log10 K CdL for either GLDA (13.03 > 12.74 > 11.60 > 11.52 > 10.31) or HIDS (12.63 > 11.30 > 10.21 > 9.76 > 7.58). In each case, the constants obtained for metal-GLDA complexes were larger than the corresponding constants for metal-HIDS complexes. The conditional stability constants (log10 $$ K-{\text{ML}}^{'} $$) of the metal-chelant complexes containing GLDA and HIDS were calculated in terms of pH, and compared with the stability constants for EDTA and other biodegradable chelants. © 2012 Springer Science+Business Media New York.
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| 7.
論文 |
論文
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Hasegawa, Hiroshi ; Rahman, Ismail M. M. ; Egawa, Yuji ; Sawai, Hikaru ; Begum, Zinnat A. ; Maki, Teruya ; Mizutani, Satoshi
概要:
The metal indium termed as 'rare' in recent days due to its increasing demand in the formulations of electronic and ener
…
gy-related gadgets and scarce supply resources. Hence, the attempts to recover indium from the secondary resources, such as recycling of the indium abundant waste materials, received increasing research focus. The major indium consumption happens in the form of indium tin oxide (ITO) that used for the fabrication of liquid-crystal displays (LCD). The end-of-life LCD screens, termed as ITO-glass hereafter, are an emerging contributor to the global e-waste load and can be an impending secondary source of indium. The present work introduces a new technique for the treatment of waste ITO-glass using aminopolycarboxylate chelants (APCs) in combination with a mechanochemical treatment process. APCs are capable of forming stable complexes with the indium deposited on the ITO-glass, whereas the rate of recovery was not substantial. The mechanochemical treatment induces the destruction of crystalline structure with which the ITO fragments are attached and facilitate the increased indium dissolution with the chelants. The increase was more prominent followed by a decrease in the cumulative processing time from 24 to 6 h when the vitrified ITO-glass was simultaneously crushed and washed with the chelants. The extraction of indium was better at the acidic pH condition, and it was further intensified when the operating temperature was raised to ≥ 120 °C. © 2012 Elsevier B.V. All rights reserved.
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| 8.
論文 |
論文
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Hasegawa, Hiroshi ; Rahman, Ismail M. M. ; Egawa, Yuji ; Sawai, Hikaru ; Begum, Zinnat A. ; Maki, Teruya ; Mizutani, Satoshi
概要:
Indium is a rare metal that is mostly consumed as indium tin oxide (ITO) in the fabrication process of liquid crystal di
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splay (LCD) panels. The spent LCD panels, termed as LCD-waste hereafter, is an increasing contributor of electronic waste burden worldwide and can be an impending secondary source of indium. The present work reports a new technique for the reclamation of indium from the unground LCD-waste using aminopolycarboxylate chelants (APCs) as the solvent in a hyperbaric environment and at a high-temperature. Microwave irradiation was used to create the desired system conditions, and a substantial abstraction of indium (≥80%) from the LCD-waste with the APCs (EDTA or NTA) was attained in the acidic pH region (up to pH 5) at the temperature of ≥120. °C and the pressure of ~50. bar. The unique point of the reported process is the almost quantitative recovery of indium from the LCD-waste that ensured via the combination of the reaction facilitatory effect of microwave exposure and the metal extraction capability of APCs. A method for the selective isolation of indium from the extractant solution and recycle of the chelant in solution is also described. © 2013 Elsevier B.V.
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| 9.
論文 |
論文
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Hasegawa, Hiroshi ; Rahman, Ismail M. M. ; Egawa, Yuji ; Sawai, Hikaru ; Begum, Zinnat A. ; Maki, Teruya ; Mizutani, Satoshi
概要:
The incineration fly ash (IFA), molten fly ash (MFA), thermal power plant fly ash (TPP-FA), and nonferrous metal process
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ing plant ash (MMA) have been screened in terms of the following rare-termed metal contents: B, Ce, Co, Dy, Eu, Ga, Gd, Hf, In, Li, Lu, Mn, Nb, Nd, Ni, Pr, Rb, Sb, Se, Sm, Sr, Ta, Tb, Te, Ti, Tm, V, W, Y, and Yb. The pseudo-potential for recycling of the waste ashes, as compared to the cumulative concentration in the crust (mg kg-1), was determined as follows: MMA > IFA > MFA > TPP-FA. The comparison with the crude ore contents indicates that the MMA is the best resource for reprocessing. The recovery of the target metals using aminopolycarboxylate chelants (APCs) has been attempted at varying experimental conditions and ultrasound-induced environment. A better APC-induced extraction yield can be achieved at 0.10 mol L-1 concentration of chelant, or if the system temperature was maintained between 60 to 80 °C. Nevertheless, the mechanochemical reaction induced by the ultrasound irradiation has been, so far, the better option for rare metal dissolution with chelants as it can be conducted at a minimum chelant concentration (0.01 mol L-1) and at room temperature (25 ± 0.5 °C). © 2014 Springer International Publishing Switzerland.
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