Attachment of 2-aminomethylpyridine molecule onto grafted silica gel surface and its ability in chelating cations

doi:10.1016/j.poly.2003.11.051

Polyhedron

Volume 23, Issue 5, 4 March 2004, Pages 719-725

https://doi.org/10.1016/j.poly.2003.11.051 Get rights and content

Abstract

A route for incorporating the chelate molecule, AMP, onto silica gel was established. In the first stage a precursor silylant agent, 3-chloropropyltrimethoxysilane, is reacted with the support. The chelate molecule was then covalently bonded to the precursor surface to give 0.76 mmol of chelate per gram of silica. The immobilization reaction was confirmed through infrared spectroscopy and thermogravimetry. The anchored surface showed ability for adsorbing cations from water solution, presenting the maximum adsorption, calculated from the Langmuir equation, of: 0.84, 0.67, 0.40 and 0.22 mmol g⁻¹ for the divalent cations copper, cobalt, nickel and zinc, respectively. All cation/surface interactions showed favorable enthalpic and entropic values, reflected in a thermodynamic stability of the complex formed.

The chelate molecule, 2-aminomethylpyridine (AMP), was attached to previous chemical modified silica, to give a degree of pendant groups of 0.76 mmol per gram of silica. The new synthesized surface has property in cation removal from aqueous solution, as expressed by favorable thermodynamic data.

Introduction

Heavy metal ion removal from waste-waters has been the subject of extensively technological research and recovering processes can often result in considerable cost saving [1]. Such analytical procedure developments are widely encouraged because many metals attain toxicity at distinct levels [2] or can show either vital or toxic effects in a series of biological systems as a function of concentration [2], [3]. Therefore, increasing pressure from environmental authorities forces the establishment of discharge limits, which in turn, require an effective use of decontamination and purification methods [4].

A series of approaches can be applied to metal ion removal from waters, based on precipitation, exchange resins, membrane filtration and adsorbent methods. Among a diversity of adsorptive compounds that are capable of adsorbing metal ions from water, activated charcoal and clays are applied on a large scale [1], [5], [6]. However, some disadvantages such as heterogeneous pore structure and low selectivity are detected for these materials. Bearing in mind this proposal, new adsorbent materials are now being employed for removal of toxic and valuable compounds from water and other solvents [7], [8], [9], [10].

Covalent immobilization onto solid supports of a desired chelate moiety, with the specific purpose of obtaining selectively adsorbent materials, is one of the most important procedures to develop highly selective matrices [11]. Therefore, considering such a proposal, many organic polymers and inorganic oxides have been chemically modified by attaching chelate groups onto the backbone chain, in order to increase their technological and scientific capabilities [12], [13], [14], [15], [16], [17], [18], [19]. Among a series of these important supports, silica gel presents a high thermal, chemical and mechanical stability [20] and enables chemical modifications with functional compounds through the available silanol groups dispersed on its surface [21]. Thus, the ability of such a support to be modified leads to the acquisition of new materials, which can be used in many applications, such as chromatography [22], in sensors [23], pesticides removal [24], as well as in catalysis [25].

Designed applications to improve environmental quality through metal removal have recently been emerged. Moreover, the versatility of the inorganic silica support to be chemically modified induces its application to produce new materials available to remove contaminants from water and other solvents [26].

The aim of the present investigation is to report the incorporation of the 2-aminomethylpyridine (AMP) molecule onto a previously modified silica gel surface and the ability of this new chelating moiety on this anchored surface for cation removal from water.

Section snippets

Chemicals

Reagent grade solvents were used. The compounds 2-aminomethylpyridine (AMP) and 3-chloropropyltrimethoxysilane (CTS) were used without purification. Silica gel with a particle size of 70–230 mesh and average pore diameter of 60 Å was activated in a stream of dry nitrogen by heating at 423 K for 10 h and used immediately [7]. The triethylamine was distilled under reduced pressure before use.

Organofunctionalization

A sample of 20.0 g of activated silica gel was suspended in 100 cm³ of dry toluene and 20.0 cm³ (108.0

Results and discussion

The attachment of the 2-aminomethylpyridine onto silica gel followed a sequence of two distinct steps. The first one consisted in grafting 3-chloropropyltrimethoxysilane (CTS) onto silica gel to yield the new surface, SiCl, as represented in Eq. (1). In the next stage, this precursor was reacted with 2-aminomethylpyridine (AMP) to give the product SiAMP, presented in Eq. (2).

The degree of immobilization on the surface was determined by considering the elemental analysis data. From the

Conclusion

The success of the 2-aminomethylpyridine chelate molecule attachment onto a silica gel surface and the ability of this material in easily adsorbing metal ions from water have been demonstrated. This proposal is confirmed through stable complexes formed between cations and free electron pairs on the nitrogen atoms disposed on the pendant groups, whose behavior was proven by the thermodynamic results. Thus, this new surface is a promising material to be applied to cation removal from aqueous

Acknowledgements

The authors are indebted to FAPESP for financial support and for a fellowship to AGSP, and to CNPq for fellowships to F.P.F., J.A.A.S. and C.A.

References (41)

B. Lee et al.
Microp. Mesop. Mater.
(2001)
S. Samal et al.
Talanta
(2002)
C. Borgo et al.
J. Colloid. Interface Sci.
(2002)
L. Mercier et al.
Microp. Mesop. Mater.
(1998)
O.A. Zaporozhets et al.
Talanta
(2002)
C.R. Silva et al.
J. Chromatogr. A
(2003)
A.G.S. Prado et al.
J. Colloid. Interface Sci.
(2001)
J.A.A. Sales et al.
Polyhedron
(2002)
L.N.H. Arakaki et al.
J. Colloid. Interface Sci.
(2002)
C. Airoldi et al.
J. Colloid. Interface Sci.
(2002)

C. Airoldi et al.

Polyhedron

(2001)

L.N.H. Arakaki et al.

J. Colloid Interface Sci.

(2000)

K. Albert et al.

J. Chromatogr.

(1991)

J.W. Moore et al.

Heavy Metals in Natural Waters

(1984)

A.A. Mozeto et al.

Quim. Nova

(2002)

J.S. Kim et al.

Sep. Sci. Technol.

(1999)

J.S. Kim et al.

J. Chem. Technol. Biotechnol.

(1999)

A.G.S. Prado et al.

J. Chem. Soc., Dalton Trans.

(2001)

M.A. Zolfigol et al.

Green Chem.

(2002)

O.A. Zaporozhets et al.

J. Anal. Chem.

(2000)

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Attachment of 2-aminomethylpyridine molecule onto grafted silica gel surface and its ability in chelating cations

Abstract

Introduction

Section snippets

Chemicals

Organofunctionalization

Results and discussion

Conclusion

Acknowledgements

Microp. Mesop. Mater.

Talanta

J. Colloid. Interface Sci.

Microp. Mesop. Mater.

Talanta

J. Chromatogr. A

J. Colloid. Interface Sci.

Polyhedron

J. Colloid. Interface Sci.

J. Colloid. Interface Sci.

Polyhedron

J. Colloid Interface Sci.

J. Chromatogr.

Heavy Metals in Natural Waters

Quim. Nova

Sep. Sci. Technol.

J. Chem. Technol. Biotechnol.

J. Chem. Soc., Dalton Trans.

Green Chem.

J. Anal. Chem.