Adsorption and coprecipitation of single heavy metal ions onto the hydrated oxides of iron and chromium

Crawford, Russell J.; Harding, Ian H.; Mainwaring, David E.

doi:10.1021/la00035a051

Cited by 138 publications

(91 citation statements)

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“…Laboratory studies have shown that for some systems macroscopic sorption behaviors (including pH-dependent sorption edges and extent of uptake) differ if the contact method is CPT versus ADS (Charlet and Manceau, 1992;Crawford et al, 1993;Waychunas et al, 1993;Karthikeyan et al, 1997;. The differences or similarities are often assumed to be caused by the atomic environment in which the trace metal is associated with the host material.…”

Section: Discussion Of Pb-fe Coprecipitation Mechanismsmentioning

confidence: 99%

“…(1) Separate Pb phases, perhaps as a result of local high pH during titration, were precipitated during the CPT experiments and the Pb phases are mechanically enveloped by iron oxyhydroxides (Schroth, 1994); (2) CPT represents enhanced surface area or site availability (Corey, 1981;Crawford et al, 1993;Karthikeyan et al, 1997); (3) CPT represents a greater binding strength (having multiple surface site types) over a simple precipitate surface (ADS having a single surface type) (Taylor, 1973;Crawford et al, 1993); and (4) CPT represents solid solution formation by heavy metal incorporation into the hydrous oxide lattice (Karthikeyan et al, 1997;Martinez and Mcbride, 1998).…”

Section: Discussion Of Pb-fe Coprecipitation Mechanismsmentioning

confidence: 99%

“…Previous work shows that sorption isotherms and sorption pH edges prepared with ADS and CPT experimental procedures are appreciably different for Cu 2+ sorption onto hydrous iron and aluminum oxides (Karthikeyan et al, 1997. As 5+ sorption onto ferrihydrite, and Ni 2+ and Cr 3+ sorption onto hydrous iron oxides (Crawford et al, 1993) show similar patterns for ADS and CPT, with coprecipitation being the more efficient process for metal removal from aqueous solutions. CPT sorption edges are located up to 2.6 pH units lower on the uptake-pH diagrams.…”

Section: Introductionmentioning

confidence: 92%

“…At the same sorbate/sorbent ratio, metal uptake is enhanced in CPT systems as compared to the ADS system (Charlet and Manceau, 1992;Waychunas et al, 1993;Karthikeyan et al, 1997). However, to illustrate the complexity of the metastable system and metal specific nature, CPT and ADS sorption edges with Zn 2+ on iron oxyhydroxide (Crawford et al, 1993) and Cu 2+ on hydrous aluminum hydroxide (Karthikeyan et al, 1997) show no appreciable differences, and contradictory experimental results for CPT-ADS have been found for Cu 2+ sorption onto iron oxyhydroxide (Swallow et al, 1980;Karthikeyan et al, 1997).…”

Section: Introductionmentioning

confidence: 98%

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Lead coprecipitation with iron oxyhydroxide nano-particles

Lü

Nuhfer

Kelly

et al. 2011

Geochimica et Cosmochimica Acta

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Pb 2+ and Fe 3+ coprecipitation was studied with sorption edge measurements, desorption experiments, sorbent aging, High Resolution Transmission and Analytical Electron Microscopy (HR TEM-AEM), and geochemical modeling. Companion adsorption experiments were also conducted for comparison. The macroscopic chemical and near atomic scale HRTEM data supplemented our molecule scale analysis with EXAFS (Kelly et al., 2008). Coprecipitation of Pb 2+ with ferric oxyhydroxides occurred at $pH 4 and is more efficient than adsorption in removing Pb 2+ from aqueous solutions at similar sorbate/sorbent ratios and pH. X-ray Diffraction (XRD) shows peaks of lepidocrocite and two additional broad peaks similar to fine particles of 2-line ferrihydrite (2LFh). HRTEM of the Pb-Fe coprecipitates shows a mixture of 2-6 nm diameter spheres and 8-20 by 200-300 nm needles, both uniformly distributed with Pb 2+ . Geochemical modeling shows that surface complexation models fit the experimental data of low Pb:Fe ratios when a high site density is used. Desorption experiments show that more Pb 2+ was released from loaded sorbents collected from adsorption experiments than from Pb to Fe coprecipitates at dilute EDTA concentrations. Desorbed Pb 2+ versus dissolved Fe 3+ data show a linear relationship for coprecipitation (CPT) desorption experiments but a parabolic relationship for adsorption (ADS) experiments.Based on these results, we hypothesize that Pb 2+ was first adsorbed onto the nanometer-sized, metastable, iron oxyhydroxide polymers of 2LFh with domain size of 2-3 nm. As these nano-particles assembled into larger particles, some Pb 2+ was trapped in the iron oxyhydroxide structure and re-arranged to form solid solutions. Therefore, the CPT contact method produced more efficient removal of Pb 2+ than the adsorption contact method, and Pb 2+ bound in CPT solids represent a more stable sequestration of Pb 2+ in the environment than Pb 2+ adsorbed on iron oxyhydroxide surfaces.

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Section: Discussion Of Pb-fe Coprecipitation Mechanismsmentioning

confidence: 99%

Section: Discussion Of Pb-fe Coprecipitation Mechanismsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 92%

Section: Introductionmentioning

confidence: 98%

See 2 more Smart Citations

Lead coprecipitation with iron oxyhydroxide nano-particles

Lü

Nuhfer

Kelly

et al. 2011

Geochimica et Cosmochimica Acta

View full text Add to dashboard Cite

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“…The toxicity level of a heavy metal could be higher if it binds with other heavy metals [1][2][3]. Metal-finishing industries are the common sources of the toxicwastewater in Malaysia [4].…”

Section: Introductionmentioning

confidence: 99%

Treatment of automotive wastewater by coagulation-flocculation using poly-aluminum chloride (PAC), ferric chloride (FeCl3) and aluminum sulfate (alum)

Bakar

Halim

2013

AIP Conference Proceedings

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Adsorption of heavy metal ions from aqueous solution onto chitosan entrapped CM‐cellulose hydrogels synthesized by irradiation

Zhao

Mitomo

2008

J of Applied Polymer Sci

131

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The application of novel environmentconscious hydrogels as an adsorbent for heavy metal ions adsorption from aqueous solutions was examined. Chitosan was blended with highly concentrated carboxymethylated cellulose (CM-cellulose) solution to form CM-cellulose/chitosan physical hydrogels, which were crosslinked by additionless irradiation technique. The adsorptive properties of the blend hydrogels against some divalent heavy metal ions were investigated by batch adsorption method. It was found that the addition of chitosan increased the crosslinking degree and the adsorption capacity of the blend hydrogels. As a typical example, experimental data of Cu(II) ion were exploited for kinetic and isothermal evaluations. Copper adsorption process was found to be initially transportcontrolled, and its adsorption isotherm can be fitted well into the Langmuir equation. Cu(II) adsorption mechanism can be viewed as the complexation of the Cu(II) with carboxyl groups and amino groups on the CM-cellulose/chitosan gel during the adsorption. From these preliminary evaluations, it is possible to conclude that the CM-cellulose/chitosan blend hydrogels have great potential for applications in water treatment for the removal of heavy metal ions.

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Adsorption and coprecipitation of single heavy metal ions onto the hydrated oxides of iron and chromium

Cited by 138 publications

References 0 publications

Lead coprecipitation with iron oxyhydroxide nano-particles

Lead coprecipitation with iron oxyhydroxide nano-particles

Treatment of automotive wastewater by coagulation-flocculation using poly-aluminum chloride (PAC), ferric chloride (FeCl3) and aluminum sulfate (alum)

Adsorption of heavy metal ions from aqueous solution onto chitosan entrapped CM‐cellulose hydrogels synthesized by irradiation

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