A novel process utilizing subcritical water and nitrilotriacetic acid to extract hazardous elements from MSW incinerator fly ash

Zhang, Fu-Shen; Itoh, Hideaki

doi:10.1016/j.scitotenv.2006.04.015

Cited by 17 publications

(9 citation statements)

References 17 publications

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“…Comparatively, SCW-NaOH process could greatly enhance the extraction efficiency, since glass network could be broken down efficiently by supercritical water, as reported by a previous study [38].…”

Section: Scw-naoh Treatment Processsupporting

confidence: 57%

Effective utilization of waste cathode ray tube glass—Crystalline silicotitanate synthesis

Chen

Zhang

Zhu

2010

Journal of Hazardous Materials

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a b s t r a c tA novel process for crystalline silicotitanate (CST) synthesis was developed using waste cathode ray tube (CRT) panel glass as silicon source. The key trait of the process was to extract most of the silicon out of the glass for CST preparation, but leave Ba and Sr in the residue which had the potential to be employed as raw material for metallic Ba and Sr metallurgy. In the synthesis process, waste CRT panel glass was firstly treated by supercritical water (SCW)-NaOH solution for Si extraction, then sol-gel and hydrothermal treatments were used for CST preparation. 80% of Si in the glass could be extracted into the solution, while Sr and Ba were enriched in the residue in the form of Sr 2 SiO 4 and Ba 2 Si 3 O 8 , respectively. Sr and Ba contents in the residue were 2-3 times higher than those in the raw glass. SEM, XRD and TEM results indicated that CST was successfully synthesized. Ion exchanging experiments showed that the batch distribution coefficient of the synthesized CST to Cs + was up to 1.2 × 10 4 mL/g at pH 0.26.

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Section: Scw-naoh Treatment Processsupporting

confidence: 57%

Effective utilization of waste cathode ray tube glass—Crystalline silicotitanate synthesis

Chen

Zhang

Zhu

2010

Journal of Hazardous Materials

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“…In addition, according to our previous studies (Zhang and Itoh, 2006;Bo et al, 2009;Xiu and Zhang, 2010), supercritical fluid such as water and methanol is strong enough to destroy the solid particles such as fly ash or waste PCBs particles. An increasing number of porous structures can be produced in the solid waste particle as the reaction temperature rise during the SCWD process.…”

Section: Effect Of Scwd On Metals Leaching Efficiency In Leaching Promentioning

confidence: 96%

Recovery of metals from waste printed circuit boards by supercritical water pre-treatment combined with acid leaching process

2013

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a b s t r a c tWaste printed circuit boards (PCBs) contain a large number of metals such as Cu, Sn, Pb, Cd, Cr, Zn, and Mn. In this work, an efficient and environmentally friendly process for metals recovery from waste PCBs by supercritical water (SCW) pre-treatment combined with acid leaching was developed. In the proposed process, waste PCBs were pre-treated by SCW, then the separated solid phase product with concentrated metals was subjected to an acid leaching process for metals recovery. The effect of SCW pre-treatment on the recovery of different metals from waste PCBs was investigated. Two methods of SCW pre-treatment were studied: supercritical water oxidation (SCWO) and supercritical water depolymerization (SCWD). Experimental results indicated that SCWO and SCWD pre-treatment had significant effect on the recovery of different metals. SCWO pre-treatment was highly efficient for enhancing the recovery of Cu and Pb, and the recovery efficiency increased significantly with increasing pre-treatment temperature. The recovery efficiency of Cu and Pb for SCWO pre-treatment at 420°C was 99.8% and 80%, respectively, whereas most of the Sn and Cr were immobilized in the residue. The recovery of all studied metals was enhanced by SCWD pre-treatment and increased along with pre-treatment temperature. Up to 90% of Sn, Zn, Cr, Cd, and Mn could be recovered for SCWD pre-treatment at 440°C.

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“…The possible reason is that the direct gasification of the polymer materials in the waste PCBs became more effectively when the reaction pressure increased. According to our previous studies [29,30], supercritical fluid is strong enough to destroy the solid particles, this treatment process could produce some porous structure in the solid waste particle. As a result, SCM molecules probably can diffuse into the waste PCBs particle through the porous structure and eventually create big holes in the particle.…”

Section: Effect Of Reaction Pressure On the Productsmentioning

confidence: 99%

Materials recovery from waste printed circuit boards by supercritical methanol

Xiu

Zhang

2010

Journal of Hazardous Materials

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a b s t r a c tThe recovery of valuable materials from waste printed circuit boards (PCBs) is quite difficult due to the heterogeneous mix of polymer materials, multiple kinds of metals and glass fiber. A feasibility study was conducted using supercritical methanol (SCM) to simultaneously recover polymers and metals from waste PCBs. The study focused on the characteristics of both oils and solid products obtained from the SCMtreated waste PCBs. The operation conditions were temperature range of 300-420• C, treatment time between 30 and 120 min and solid-to-liquid ratio (S/L) of 1:10-1:30 (g/mL) so as to understand the products and depolymerization mechanisms of waste PCBs in SCM. GC-MS results revealed that the oils mainly contained phenol and its methylated derivatives, and the methylated derivatives increased with the increase of reaction temperature. The methylated reaction occurred mainly above 400• C. The liquid products also contained a significant number of phosphated fire retardant additives such as triphenyl phosphate, which decreased significantly with the increase of reaction temperature. The solid product mainly consisted of Cu, Fe, Sn, Pb and Zn, as well as lower concentrations of precious metals such as Ag and Au.

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A novel process utilizing subcritical water and nitrilotriacetic acid to extract hazardous elements from MSW incinerator fly ash

Cited by 17 publications

References 17 publications

Effective utilization of waste cathode ray tube glass—Crystalline silicotitanate synthesis

Effective utilization of waste cathode ray tube glass—Crystalline silicotitanate synthesis

Recovery of metals from waste printed circuit boards by supercritical water pre-treatment combined with acid leaching process

Materials recovery from waste printed circuit boards by supercritical methanol

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