3-(Trimethoxysilyl)-1-propanethiol Supported on Silica Gel for the Separation and Preconcentration of Copper and Cadmium in Water

Abstract

The preparation and characteristics of thiol-modified silica and its application to the preconcentration and determination of trace amounts of copper and cadmium by flame atomic absorption spectrometry are described. For the preparation of modified silica, the untreated silica suspended in methanol was impregnated with 3-(trimethoxysilyl)-1-propanethiol to obtain thiol-modified silica and the methanol was evaporated under vacuum. The residual silica was dried at 150° C and washed with distilled water until the washings appeared clear. The surface area of thiol-modified silica was 410 m2/ g, whereas the copper capacity was about 0.022 mmolCu/ g silica. Batch and column methods were used for the separation and concentration of the above-mentioned metals. These metals were quantitatively retained on the adsorbent at acidic media. In the batch method, the effects of pH, shaking time and the kind of buffer on adsorption of copper and cadmium were investigated. The shaking time of 30 min was sufficient for a quantitative adsorption of the metals. In the column and batch procedures, both copper and cadmium adsorbed on the modified silica were quantitatively recovered with 2 M hydrochloric acid. Sodium chloride (up to 1%) had no effects on the recoveries.

Chemisorption on Thiol–Silicas: Divalent Cations as a Function of pH and Primary Amines on Thiol–Mercury Adsorbed

“…The behavior of the adsorption is coherent with other literature data, where cations as copper, nickel, and cobalt presented very low adsorption levels with modified silicas when sulphur was used as Lewis base (12,13,15,24). The amount of adsorbed mercury on GSi-SH was found as 0.85 mmol per gram of silica.…”

“…was well defined at 2560 cm 01 (15). On the other hand, The batch method was used to adsorb cations onto GSi-thermogravimetric curves and solid state 13 C-NMR gave SH in each buffered medium. For these adsorption measure-conclusive evidence for the immobilization of the mentioned ments (19), samples of about 0.10 g of the functionalized silylant molecule.…”

O uso de sílica gel organofuncionalizada como agente sequestrante para metais

“…Para a reação do cátion, na forma MX 2 com a superfície imobilizada em suspensão, Sup, em um determinado solvente, podemos escrever: O avanço dos aspectos sintéticos possibilitou a incorporação de uma variedade de moléculas no arcabouço da estrutura inorgânica polimérica da sílica, contendo diversos centros bási-cos em suas estruturas, no que resultou uma condição de uso destas superfícies como agentes quelantes . Nestas matrizes, as espécies químicas responsáveis pela adsorção de metais apresentam nitrogênio [76][77][78][79][80][81][82][83][84][85][86][87][88] , oxigênio [89][90][91][92][93][94][95][96][97][98][99] , ou enxofre [100][101][102][103][104][105][106][107][108][109][110][111][112][113][114] , como áto-mo doador.…”

Chelating Resins and Their Applications in the Analysis of Trace Metal Ions

“…Since a number of potentially suitable acidic and basic eluting agents were all ineffective in removing arsenic from the mercapto modified silica, they oxidized arsenite to arsenate by eluting with 2.0 g liter Ϫ1 potassium iodate solution in 0.5 M hydrochloric acid. This resin was also used by Akman et al as adsorbent for preconcentration of Cu 2ϩ and Cd 2ϩ in water (93). These metals were quantitatively retained on the adsorbent at acidic media with a capacity for Cu 2ϩ being 0.022 mmol g Ϫ1 modified silica.…”