Process evaluation for optimization of EDTA use and recovery for heavy metal removal from a contaminated soil

Lim, Teik−Thye; Chui, Pengfei; Goh, Kok-Hui

doi:10.1016/j.chemosphere.2004.09.046

Cited by 99 publications

(72 citation statements)

References 24 publications

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“…2013.03.028 from the spent catalysts [16]. However, APCs have rarely been used to treat any vitrified waste [10] in spite of being praised for excellent metal-binding capacities and extensive use in the treatment of contaminated soil solids [17][18][19][20]. Hence, the current report is an effort to comprehend the potential of APCs for indium extraction from the ITO-film composed to a dense vitrified structure.…”

Section: Introductionmentioning

confidence: 99%

Chelant-induced reclamation of indium from the spent liquid crystal display panels with the aid of microwave irradiation

Hasegawa¹,

Rahman²,

Egawa³

et al. 2013

Journal of Hazardous Materials

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Section: Introductionmentioning

confidence: 99%

Chelant-induced reclamation of indium from the spent liquid crystal display panels with the aid of microwave irradiation

Hasegawa¹,

Rahman²,

Egawa³

et al. 2013

Journal of Hazardous Materials

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Section: Introductionmentioning

confidence: 99%

“…However, the Microchemical Journal (In Press). DOI: http://dx.doi.org/10.1016/j.microc.2012.08.010 4 aminopolycarboxylate chelants (APCs) have not been evaluated for the recovery of indium in spite of their widespread acclaim for excellent metal-binding capacities [13][14][15].A novel way for processing of solid materials is the co-grinding with suitable additives, commonly known as mechanochemical treatment [16][17][18]. The process includes the treatment of the materials in a closed mill containing balls that aid repeated fracturing via high-energy collisions either between balls or ball and inner wall of the mill container [19].…”

mentioning

confidence: 99%

Recovery of indium from end-of-life liquid-crystal display panels using aminopolycarboxylate chelants with the aid of mechanochemical treatment

Hasegawa

Rahman

Egawa

et al. 2013

Microchemical Journal

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The metal indium termed as 'rare' in recent days due to its increasing demand in the formulations of electronic and energy-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. Keywords:Indium; Indium tin oxide; Liquid crystal display; Waste; Recovery; Mechanochemical treatment Microchemical Journal (In Press). DOI: http://dx.doi.org/10.1016/j.microc.2012.08.010 3 IntroductionIndium has emerged as an important strategic element in electronic and energy-related industries due to its specific applications [1,2]. The most important end use of indium in recent years is to manufacture indium-tin oxide (ITO) thin film, an optoelectronic material with the characteristics of transparency to visible light, electric conduction and thermal reflection [2,3]. ITO thin film is widely used in designing liquid-crystal displays (LCD), plasma displays and solar-energy cell [3], and consume about two-third of the global indium production [4].Indium has no ore of its own and is generally found in low concentrations in some sulphide ores of zinc, copper and lead, from which it is procured as a by-product [5]. The technology revolution created an increasing demand for indium while the boom in its price is due to the policies of the nations with indium reserves (e.g. China, South Korea). Hence, the recovery of indium from the waste resources received sincere focus from the researches [4-6].The ITO-scrap resulted from the ITO ceramic target during the conversion and application of ITO thin films on glass panels using the DC magnetron sputtering process is the most potential secondary resource of indium [2,3,6,7]. The other prospective waste resources of indium are the etching waste [1,8] and the LCD powder [6,9].The end-of-life (EoL) LCDs are a gr...

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“…The cost of chelants is also an important issue surrounding their use in metal ion sequestration. Methods that recycle not only the processed water, but also the chelant, may therefore be economically feasible (Lim et al, 2005;Leštan et al, 2008).Separation and pre-concentration of metal ions from aqueous solutions using solid sorbent materials, known as solid phase extraction (SPE) systems, have increased in popularity since the 1980s (Hosten and Welz, 1999). Some of the sorbent materials have the capability to interact with a variety of metal ions, while others are fairly specific for a particular ion (Ebdon et al, 1991; Carbonell et al, 1992;Nickson et al, 1995; Ghaedi et al, 2006; Ghaedi et al, 2007; Ghaedi et al, 2008).…”

mentioning

confidence: 99%

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confidence: 99%

Non-destructive separation of metal ions from wastewater containing excess aminopolycarboxylate chelant in solution with an ion-selective immobilized macrocyclic material

et al. 2010

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Although the excellent metal-binding capacities of aminopolycarboxylate chelants (APCs) facilitate their extensive use, pre-and post-toxicity of APCs and their high persistence in aquatic environments evoke concerns. Several treatment techniques with a principal focus on the degradation of APCs at the pre-release step have been proposed. Here, we report a technique for the separation of metal ions from waste solution containing excess APCs using a solid phase extraction system with an ion-selective immobilized macrocyclic material, commonly known as a molecular recognition technology (MRT) gel. Synthetic metal solutions with 100-fold chelant content housed in H 2 O matrices were used as samples.The MRT gel showed a higher recovery rate compared with other SPE materials at 20 °C using a flow rate of 0.2 mL min -1 . The effects of solution pH, metal-chelant stability constants and ionic radii were assessed for 32 metals. Compared to the conventional treatment options for such waste solutions, our proposed technique has the advantage of nondestructive separation of both metal ions and chelants. (Ayres, 1970; Bell, 1977; Grasso, 1993;Roundhill, 2001 APCs have been introduced into the natural environment, the aqueous transport of metals, which characteristically form stable complexes with chelates, can be expected to occur (Means et al., 1980;Nowack and VanBriesen, 2005). Residence time of the metals is thus extended, as they are remobilized from soils and sediments into the water phase. EDTA and its homologs are poorly photo-, chemo-and biodegradable in the environment (Means et al., 1980; Bolton Jr. et al., 1993;Kari and Giger, 1995; Egli, 2001;Nowack, 2002;Nörtemann, 2005) and, in most cases, metal complexation raises the threshold values for toxic effects (Sillanpää and Oikari, 1996;Sorvari and Sillanpää, 1996;Sillanpää, 2005).Excess chelant also increases the total nitrogen content and the phosphate solubility in interstitial waters (Norvell, 1984; Horstmann and Gelpke, 1991; Erel and Morgan, 1992;Li and Shuman, 1996; Hering and Morel, 2002).Wastewater with excess APCs entails subsequent separation or degradation treatment before it can be safely discharged. In Europe, treatment of EDTA-containing wastewaters is increasingly required because of the increasingly stringent environmental regulations (Grundler et al., 2005; van Ginkel and Geerts, 2005). Several processes have been proposed for the degradation of APCs to restrict their intrusion to the environment (Sillanpää and Oikari, 1996; Kagaya et al., 1997;Madden et al., 1997;Krapfenbauer and Getoff, 1999;Muñoz and von Sonntag, 2000;Rämö et al., 2000; Bucheli-Witschel and Egli, 2001;Rämö and Sillanpää, 2001;Sillanpää and Pirkanniemi, 2001;Sillanpää and Rämö, 2001;Pirkanniemi et al., 2007). The cost of chelants is also an important issue surrounding their use in metal ion sequestration. Methods that recycle not only the processed water, but also the chelant, may therefore be economically feasible (Lim et al., 2005;Leštan et al., 2008).Separation and pre-conce...

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Process evaluation for optimization of EDTA use and recovery for heavy metal removal from a contaminated soil

Cited by 99 publications

References 24 publications

Chelant-induced reclamation of indium from the spent liquid crystal display panels with the aid of microwave irradiation

Chelant-induced reclamation of indium from the spent liquid crystal display panels with the aid of microwave irradiation

Recovery of indium from end-of-life liquid-crystal display panels using aminopolycarboxylate chelants with the aid of mechanochemical treatment

Non-destructive separation of metal ions from wastewater containing excess aminopolycarboxylate chelant in solution with an ion-selective immobilized macrocyclic material

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