Simultaneous preconcentration of Cu(II), Cd(II) and Mn(II) on silica-polyethylene glycol and determination by flame atomic absorption spectrometry

Abstract

Recebido em 26/1/12; aceito em 14/6/12; publicado na web em 21/9/12 A simultaneous solid phase extraction procedure for enrichment of Cu(II), Cd(II) and Mn(II) has been developed. The method is based on adsorption of Cu(II), Cd(II) and Mn(II) ions on polyethylene glycol-silica gel pre-conditioned with acetate buffer (pH 5.5). The adsorbed metal ions are eluted with nitric acid (1 mol L -1 ) and determined by flame atomic absorption spectrometry. The calibration graph was linear in the range of 2-140 ng mL -1 for Cu(II), 1-40 ng mL -1 for Cd(II) and 4-100 ng mL -1 for Mn(II). The limits of detection were 0.66, 0.33 and 1.20 ng mL -1 for Cu(II), Cd(II) and Mn(II), respectively.Keywords: Cu(II); Cd(II); Mn(II). INTRODUCTIONHigh concentrations of heavy metals may have severe toxicological effects on living organisms. Large amounts of heavy metals can enter the environment from metallurgy industries, combustion of coal, and automobiles. Heavy metals can easily enter the food chain through a number of pathways, and long-term exposure in a contaminated environment can cause progressive toxic effects for living organisms. Therefore, controlling heavy metal discharges and their measurement in different samples has become a challenge for analytical chemists.1,2 The flame atomic absorption spectrometry technique is extensively employed for the quantification of metallic species because of its desirable characteristics, such as low cost, ease of operation, high analytical frequency and good selectivity. However, the direct determination of trace metals by this technique is limited because of matrix interference problems and low concentration of metals in samples. However, these problems can easily be overcome by applying separation and/or preconcentration procedures before performing the detection procedure. Different methods exist for the separation and isolation of metal ions such as liquid-liquid extraction, 3 ion exchange, 4 flotation, 5 solid phase extraction 6-10 and cloud point extraction.11-13 The inherent limitations of the methods based upon solvent extraction are the high costs of solvents and the environmental concerns regarding their disposal. Hence, solid phase extraction methods were proposed as an alternative to overcome these drawbacks of liquid-liquid extraction. The separation, preconcentration, and determination of metal ions at trace levels has been successfully accomplished using different adsorbents such as polymeric resins modified with selective ligands.Solid phase extraction is an attractive separation and preconcentration technique for trace metal ions with advantages such as simplicity, flexibility, and high enrichment factors. Various solid phase materials have been introduced for the preconcentration and separation of heavy metal ions at trace levels, including chemically--modified silica-gel with amino thioamidoanthraquinone, 14 polyurethane foam functionalized with a-naphthol, 15 In this work, a solid phase extraction procedure for preconcentration of Cu(II), Cd(II) and Mn(II) using silica g...

Optimization of Cd(II) adsorption condition by glycine-modified silica-based adsorbent using central composite design

“…Hasil modifikasi dibuktikan dengan spektrum inframerah. Kondisi optimum adsorpsi Cd dengan Si-Gly diperoleh pada pH 5 , dengan bobot adsorben 0, 3 g, dan waktu kontak 11 menit. Persentase adsorpsi Cd pada kondisi optimum oleh Si-Gly ( 99 , 34 %) lebih besar daripada oleh SG ( 89 , 03 %).…”

“…Efisiensi adsorpsi Cd(II) oleh Si-Gly lebih tinggi daripada adsorpsi oleh SG. Kondisi optimum adsorpsi Cd(II) dengan Si-Gly diperoleh pada pH 5 menggunakan 0.3 g adsorben dengan waktu kontak 11 menit. Kapasitas maksimum adsorpsi Si-Gly adalah 9 , 77 mg / g yang diperoleh pada konsentrasi 400 mg / L.…”

“…Beberapa penelitian sebelumnya telah melaporkan modifikasi material fase padat berbasis silika untuk adsorpsi ion Cd(II) diantaranya 1,10-fenantrolina [8]; Piridina 2,6-diylbis( 2,2 ' (azametana-i-yliden) bromofenol) ( L) [ 9 ]; KIT-6-SH [10]; polietilen glikol ( PEG) [11]. Modifikasi adsorben lainnya yang dapat dilakukan untuk meningkatkan efisiensi dan kapasitas adsorpsi silika adalah dengan imobilisasi suatu ligan organik (organofungsionalisasi) yang memiliki atom donor (0, N , S, P) seperti asam amino.…”