Selective Adsorption of Palladium(II), Platinum(IV), and Mercury(II) on a New Chitosan Derivative Possessing Pyridyl Group

Baba, Yoshihiro; Hirakawa, Hiroyuki

doi:10.1246/cl.1992.1905

Cited by 59 publications

(22 citation statements)

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“…They readily form in solution chloropalladate and chloroplatinate anions that can be adsorbed in acidic solutions by protonated amine groups. [32,[35][36][37][38] As previously stated, in HCl solution chitosan is soluble. It is thus necessary to prevent its dissolving by a cross-linking treatment.…”

Section: Platinum and Palladium Sorption -Influence Of Metal Complexamentioning

confidence: 78%

Recovery of Metal Ions by Chitosan: Sorption Mechanisms and Influence of Metal Speciation

Navarro

Guzmán

Saucedo

et al. 2003

Macromolecular Bioscience

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Chitosan is characterized by a high affinity for metal ions due to its high content of amine groups. The sorption mechanism depends on both the protonation of these amine groups and the speciation of metal ions. Metal cations may be adsorbed at pH close to neutrality by chelation mechanism while metal anions can be adsorbed in acidic solutions through ionic interactions with protonated amine groups. Several examples are considered. The first example focuses on Cd sorption, which proceeds by a chelation mechanism on free non‐protonated amine groups in neutral media. In acidic solutions the protonation of amine groups limits the ability of amine groups to complex Cd. The cross‐linking of chitosan with glutaraldehyde also results in a dramatic decrease of sorption properties due to the decrease in the density of complexation sites available for sorption. The sorption of vanadium(V) and molybdenum(VI) illustrates the high capacity of chitosan for the sorption of oxo‐anions. They are very efficiently sorbed in acidic solutions by ionic interactions. The correlation of sorption capacities with the distribution of metal species shows that the sorbent has a greater affinity for highly charged anionic species. The sorption of complex anionic species such as chloro‐complexes of Pd and Pt; and that of copper complexed with organic ligands have also been studied. The optimum conditions for sorption are obtained when anionic complexes predominate in the solution. The chemical modification of chitosan, obtained by grafting of sulfur compounds, allows modifying the sorption mechanism: the ion‐exchange polymer is transformed to a dual ion‐exchange and chelating polymer.Copper sorption isotherm in presence of sodium citrate (0.004 M) (RNH: fraction of protonated amine groups; ACuC: total fraction of anionic copper complexes; Cu‐FAL: total fraction of copper‐free anionic ligands).magnified imageCopper sorption isotherm in presence of sodium citrate (0.004 M) (RNH: fraction of protonated amine groups; ACuC: total fraction of anionic copper complexes; Cu‐FAL: total fraction of copper‐free anionic ligands).

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Section: Platinum and Palladium Sorption -Influence Of Metal Complexamentioning

confidence: 78%

Recovery of Metal Ions by Chitosan: Sorption Mechanisms and Influence of Metal Speciation

Navarro

Guzmán

Saucedo

et al. 2003

Macromolecular Bioscience

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“…The improvement of sorption properties may also consist in grafting other N-bearing groups with acid-base properties compatible with more acidic media. A good example of these modifications is given by the immobilization of pyridyl moieties on chitosan (Baba and Hirakawa 1992;Baba et al 1996Baba et al , 1998Kagaya et al 2000;Justi et al 2004Justi et al , 2005Dhakal et al 2008;Sajomsang 2010). The present study proposes a new route for the synthesis of N-(2-(2-pyridyl)ethyl)chitosan (PEC).…”

Section: Introductionmentioning

confidence: 95%

N-(2-(2-Pyridyl)ethyl)chitosan (PEC) for Pd(II) and Pt(IV) sorption from HCl solutions

et al. 2010

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Chitosan was modified by grafting 2-pyridyl-ethyl moieties on the biopolymer backbone for the synthesis of a Platinum Group Metal (PGM) sorbent. The sorbent was tested for Pd(II) and Pt(IV) sorption from HCl solutions. Stable for HCl concentrations below 0.5 M, the sorbent reached sorption capacities as high as 3.2 and 2.6 mmol metal g -1 for Pd(II) and Pt(IV), respectively. Metal sorption mainly proceeds by electrostatic attraction in acidic solutions, though a contribution of complexation mechanism cannot be totally rejected. The resistance to intraparticle diffusion is the main controlling mechanism for uptake kinetics. While agitation speed has a limited effect on kinetics, metal concentration and sorbent dosage have a greater effect on the kinetic profiles. The intraparticle diffusivity varies between 3 9 10 -11 and 4.5 9 10 -10 m 2 min -1 . Thiourea (combined with HCl solution) is used for Pd(II) and Pt(IV) desorption. The resin could be desorbed and recycled for a minimum of five cycles maintaining high efficiencies of sorption and desorption.

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“…PMC, TMC, and MTPC were synthesized by reducing the Schiff's bases between the primary amino groups of chitosan and the corresponding carboxaldehydes, as described in the previous paper. 4 The intermediate and final products were identified by the IR spectra. The substituted degree was determined to be over 0.9 by using the C/N ratio of an elemental analysis.…”

Section: Reagents and Adsorption Proceduresmentioning

confidence: 99%

“…Recently, we newly synthesized some crosslinked chitosan derivatives available as chelating resins using chitosan. 3,4 We found that new chitosan derivatives (N-(2-pyridylmethyl)chitosan(PMC), N-(2-thienylmethyl)chitosan (TMC),propyl]chitosan(MTPC)) can selectively adsorb precious metals, such as gold(III), palladium(II), and platinum(IV) in hydrochloric acid. 3 We also found that Schiff's base formation is effective in protecting the amino group prior to the crosslinking reaction.…”

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confidence: 99%

Selective Adsorption of Mercury(II) on Chitosan Derivatives from Hydrochloric Acid

et al. 1998

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Since chitin and chitosan are structurally similar to cellulose 1,2 and are quite abundant in nature, it is very important to conduct studies on their effective applications. Although they have so far been discarded as a raw waste material, they are currently attracting much attention as a utilized resource. Recently, we newly synthesized some crosslinked chitosan derivatives available as chelating resins using chitosan. 3,4 We found that new chitosan derivatives (N-(2-pyridylmethyl)chitosan(PMC), N-(2-thienylmethyl)chitosan (TMC),propyl]chitosan(MTPC)) can selectively adsorb precious metals, such as gold(III), palladium(II), and platinum(IV) in hydrochloric acid. 3 We also found that Schiff's base formation is effective in protecting the amino group prior to the crosslinking reaction.Mercury(II) is one of the typical environmental pollutants and is, on the other hand, a useful metal indispensable for industries.5 Therefore, it is very important to develop techniques to recovery mercury(II) from various kinds of wastes, such as spent dry cells and waste water containing mercury(II). The separation techniques using chelating resin are considered to be the most effective and energy-saving separation techniques. Hence, the development of the selective adsorbent for the recovery of mercury(II) using chitosan was planned from the view points of both environmental protection and the utilization of biomass.In the present study the adsorption behaviors of mercury(II) on PMC, TMC, and MTPC from hydrochloric acid were investigated in order to develop a new adsorbent of mercury(II). Furthermore, we also examined the adsorption behavior of mercury(II) on crosslinked copper(II)-complexed chitosan (CLC) reported in a previous paper 6 for a comparison. We have discussed the relationship between the structure of the ligand in chitosan derivatives and the selectivity toward mercury(II). Experimental Reagents and adsorption proceduresChitosan (trade name, Chitosan 100L), produced and marketed by Katokichi Co. Inc. Japan, was used without further purification; the deacetylated degree was 100%. Other reagents of reagent grade were also used without further purification. All aqueous solutions were prepared with distilled and deionized water. PMC, TMC, and MTPC were synthesized by reducing the Schiff's bases between the primary amino groups of chitosan and the corresponding carboxaldehydes, as described in the previous paper. 4 The intermediate and final products were identified by the IR spectra. The substituted degree was determined to be over 0.9 by using the C/N ratio of an elemental analysis.About 0.1 g of sieved chitosan derivatives and 15 ml of an aqueous solution containing metal ion were shaken in a stoppered 50 ml glass flask immersed in a thermostated water bath maintained at 30˚C to achieve equilibration. The initial metal concentration was adjusted to 1 mmol dm -3 by dissolving metal chloride in 0.01 -6 mol dm -3 hydrochloric acid. The initial and 687 ANALYTICAL SCIENCES AUGUST 1998, VOL. 14 1998 © The Japan Society for ...

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Selective Adsorption of Palladium(II), Platinum(IV), and Mercury(II) on a New Chitosan Derivative Possessing Pyridyl Group

Cited by 59 publications

References 3 publications

Recovery of Metal Ions by Chitosan: Sorption Mechanisms and Influence of Metal Speciation

Recovery of Metal Ions by Chitosan: Sorption Mechanisms and Influence of Metal Speciation

N-(2-(2-Pyridyl)ethyl)chitosan (PEC) for Pd(II) and Pt(IV) sorption from HCl solutions

Selective Adsorption of Mercury(II) on Chitosan Derivatives from Hydrochloric Acid

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