Continuous removal of heavy metals from FGD wastewater in a fluidised bed without sludge generation

Nielsen, Peter; Christensen, T.; Vendrup, Michael

doi:10.1016/s0273-1223(97)00413-7

Cited by 12 publications

(3 citation statements)

References 2 publications

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“…Chemical precipitation of heavy metals can also be achieved by heterogeneous (surface) precipitation ( − ). That is, heavy metals are removed by deposition on the surface of some solid media; as such, the solid−liquid separation step can be easily accomplished by capturing these media.…”

Section: Introductionmentioning

confidence: 99%

Co-removal of Hexavalent Chromium through Copper Precipitation in Synthetic Wastewater

Sun

Shang

Huang

2003

Environ. Sci. Technol.

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The mechanisms of hexavalent chromium [Cr(VI)] co-removal with copper [Cu(II)] during homogeneous precipitation were studied with batch tests using a synthetic solution containing Cr(VI) and Cu(II). Metal precipitation was induced by adding Na2CO3 stepwise to different pH, and the respective removals of Cu(II) and Cr(VI) were measured. At the same time, the relative quantities of Cu(II) and Cr(VI) in the precipitates were also analyzed to establish their stoichiometric relationship. The results indicated that, in a solution containing 150 mg/L Cu(II) and 60 mg/L Cr(VI), the initial co-removal of Cr(VII with Cu(II) began at pH 5.0 and completed at pH 6.2. At pH 5.0-5.2, coprecipitation took place through the formation of copper-chromium-bearing solids [such as CuCrO4 and/or CuCrO4 x 2Cu(OH)2]. Thereafter, the remaining soluble copper started to react with carbonate in a heterogeneous environment to form the negatively charged basic copper carbonate precipitates [CuCO3 x Cu(OH)2], which subsequently adsorbed additional Cr(VI) (or HCrO4-) at pH 5.2-6.2. The maximum Cr(VI) co-removal took place at pH 6.2. Between the two mechanisms, co-precipitation accounted for about 29% of the total chromium's co-removal while the remaining 71% was attributed to surface adsorption, mainly through electrostatic attraction and ligand exchange. When the solution pH was increased to beyond 7.5, a surface charge reversal took place on the basic copper carbonate solids, and this led to some Cr(VI) desorption. Thus, the extent of Cr(VI) adsorption is highly pH dependent.

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Section: Introductionmentioning

confidence: 99%

Co-removal of Hexavalent Chromium through Copper Precipitation in Synthetic Wastewater

Sun

Shang

Huang

2003

Environ. Sci. Technol.

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“…Removal of heavy metals can also be achieved by heterogeneous (surface) precipitation. − That is, some solid media are provided to allow most of the precipitation to take place on the media surface, i.e., heterogeneous deposition. Even though some precipitation takes place in liquid phase, i.e., bulk precipitation or discrete precipitation, some of their precipitates can further adsorb or coat on the surface of solid media (others may form small particles (fines) through secondary nucleation in liquid phase).…”

Section: Introductionmentioning

confidence: 99%

Optimum pH for Cr⁶⁺ Co-removal with Mixed Cu²⁺, Zn²⁺, and Ni²⁺ Precipitation

Sun

Feng

Huang

2006

Ind. Eng. Chem. Res.

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It is advisable to co-remove Cr(VI) with available Cu(II), Zn(II), and Ni(II) since they coexist in most plating wastewater. Previous studies showed that coprecipitation and adsorption are the main mechanisms contributable to Cr(VI) co-removal with Cu(II) precipitation, and both are highly pH dependent. This study presents the effect of pH on Cr(VI) co-removal with mixed metal precipitation in batch tests and also in a continuous compact system. Batch tests indicate that a maximum of 46.8 mg L-1 Cr(VI) was co-removed with the precipitation of Cu(II), Zn(II), and Ni(II), each 150 mg L-1, at pH of 7.0−7.3. However, co-removal of Cr(VI) decreased significantly with further pH increasing. Therefore in the continuous system, a two-stage nucleated precipitation technology was designed with the first stage being operated at around pH 7.2 to obtain maximum Cr(VI) co-removal and the second stage at around pH 9.2 to achieve further Cr(VI) co-removal with Zn(II) and Ni(II) precipitation.

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“…It is important to recover and/or remove the heavy metals in these industrial waste streams to avoid contamination of the surrounding environment. Current technologies used for heavy-metal removal/recovery include precipitation, − flotation, ion-exchange resins, − membranes, , and biological systems. , …”

Section: Introductionmentioning

confidence: 99%

Synthesis and Characterization of LIX-84 Noncovalently Bound Silica Sorbents for Metal-Ion Recovery

Cooper

Yue

Gonzalez

2003

Ind. Eng. Chem. Res.

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Mesoporous silica particles were modified with LIX-84 (2-hydroxy-5-nonylacetophenome oxime). LIX-84 was attached to the surface of silica via noncovalent forces. The effects of silica particle size, pore size, temperature, and pH on metal-ion-exchange properties were studied to characterize metal ion adsorption properties for chelating groups noncovalently bound to the surface of silica. The adsorbent had a capacity of 0.6 mmol of Cu 2+ /g of adsorbent at room temperature and a capacity of 1.1 mmol of Cu 2+ /g of adsorbent at 60 °C. Depending on the solution pH, the adsorbent had varying capacity for Cu 2+ , Ni 2+ , and Pb 2+ . The adsorbent was found to have good stability and gave high metal recovery when regenerated with 2 vol % nitric acid. An increased ion-exchange rate was achieved and was attributed to the use of larger pore size silica. The silica was found to contain from 5 to 7 wt % LIX-84.

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Continuous removal of heavy metals from FGD wastewater in a fluidised bed without sludge generation

Cited by 12 publications

References 2 publications

Co-removal of Hexavalent Chromium through Copper Precipitation in Synthetic Wastewater

Co-removal of Hexavalent Chromium through Copper Precipitation in Synthetic Wastewater

Optimum pH for Cr⁶⁺ Co-removal with Mixed Cu²⁺, Zn²⁺, and Ni²⁺ Precipitation

Synthesis and Characterization of LIX-84 Noncovalently Bound Silica Sorbents for Metal-Ion Recovery

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Continuous removal of heavy metals from FGD wastewater in a fluidised bed without sludge generation

Cited by 12 publications

References 2 publications

Co-removal of Hexavalent Chromium through Copper Precipitation in Synthetic Wastewater

Co-removal of Hexavalent Chromium through Copper Precipitation in Synthetic Wastewater

Optimum pH for Cr6+ Co-removal with Mixed Cu2+, Zn2+, and Ni2+ Precipitation

Synthesis and Characterization of LIX-84 Noncovalently Bound Silica Sorbents for Metal-Ion Recovery

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Optimum pH for Cr⁶⁺ Co-removal with Mixed Cu²⁺, Zn²⁺, and Ni²⁺ Precipitation